Revision: 1118
http://www.exim.org/viewvc/pcre2?view=rev&revision=1118
Author: ph10
Date: 2019-06-22 17:36:15 +0100 (Sat, 22 Jun 2019)
Log Message:
-----------
Documentation update.
Modified Paths:
--------------
code/trunk/doc/html/pcre2pattern.html
code/trunk/doc/pcre2-config.txt
code/trunk/doc/pcre2.txt
code/trunk/doc/pcre2grep.txt
code/trunk/doc/pcre2pattern.3
code/trunk/doc/pcre2test.txt
Modified: code/trunk/doc/html/pcre2pattern.html
===================================================================
--- code/trunk/doc/html/pcre2pattern.html 2019-06-21 16:10:17 UTC (rev 1117)
+++ code/trunk/doc/html/pcre2pattern.html 2019-06-22 16:36:15 UTC (rev 1118)
@@ -3525,9 +3525,10 @@
instead of skipping on to "c".
</P>
<P>
-If (*SKIP) is used inside a lookbehind to specify a new starting position that
-is not later than the starting point of the current match, the position
-specified by (*SKIP) is ignored, and instead the normal "bumpalong" occurs.
+If (*SKIP) is used to specify a new starting position that is the same as the
+starting position of the current match, or (by being inside a lookbehind)
+earlier, the position specified by (*SKIP) is ignored, and instead the normal
+"bumpalong" occurs.
<pre>
(*SKIP:NAME)
</pre>
@@ -3754,7 +3755,7 @@
</P>
<br><a name="SEC31" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 21 June 2019
+Last updated: 22 June 2019
<br>
Copyright © 1997-2019 University of Cambridge.
<br>
Modified: code/trunk/doc/pcre2-config.txt
===================================================================
--- code/trunk/doc/pcre2-config.txt 2019-06-21 16:10:17 UTC (rev 1117)
+++ code/trunk/doc/pcre2-config.txt 2019-06-22 16:36:15 UTC (rev 1118)
@@ -16,8 +16,8 @@
pcre2-config returns the configuration of the installed PCRE2 libraries
and the options required to compile a program to use them. Some of the
- options apply only to the 8-bit, or 16-bit, or 32-bit libraries,
- respectively, and are not available for libraries that have not been
+ options apply only to the 8-bit, or 16-bit, or 32-bit libraries, re-
+ spectively, and are not available for libraries that have not been
built. If an unavailable option is encountered, the "usage" information
is output.
@@ -36,30 +36,30 @@
--version Writes the version number of the installed PCRE2 libraries to
the standard output.
- --libs8 Writes to the standard output the command line options
- required to link with the 8-bit PCRE2 library (-lpcre2-8 on
+ --libs8 Writes to the standard output the command line options re-
+ quired to link with the 8-bit PCRE2 library (-lpcre2-8 on
many systems).
- --libs16 Writes to the standard output the command line options
- required to link with the 16-bit PCRE2 library (-lpcre2-16 on
+ --libs16 Writes to the standard output the command line options re-
+ quired to link with the 16-bit PCRE2 library (-lpcre2-16 on
many systems).
- --libs32 Writes to the standard output the command line options
- required to link with the 32-bit PCRE2 library (-lpcre2-32 on
+ --libs32 Writes to the standard output the command line options re-
+ quired to link with the 32-bit PCRE2 library (-lpcre2-32 on
many systems).
--libs-posix
- Writes to the standard output the command line options
- required to link with PCRE2's POSIX API wrapper library
+ Writes to the standard output the command line options re-
+ quired to link with PCRE2's POSIX API wrapper library
(-lpcre2-posix -lpcre2-8 on many systems).
- --cflags Writes to the standard output the command line options
- required to compile files that use PCRE2 (this may include
- some -I options, but is blank on many systems).
+ --cflags Writes to the standard output the command line options re-
+ quired to compile files that use PCRE2 (this may include some
+ -I options, but is blank on many systems).
--cflags-posix
- Writes to the standard output the command line options
- required to compile files that use PCRE2's POSIX API wrapper
+ Writes to the standard output the command line options re-
+ quired to compile files that use PCRE2's POSIX API wrapper
library (this may include some -I options, but is blank on
many systems).
Modified: code/trunk/doc/pcre2.txt
===================================================================
--- code/trunk/doc/pcre2.txt 2019-06-21 16:10:17 UTC (rev 1117)
+++ code/trunk/doc/pcre2.txt 2019-06-22 16:36:15 UTC (rev 1118)
@@ -31,8 +31,8 @@
appeared in Python and the original PCRE before they appeared in Perl
are available using the Python syntax. There is also some support for
one or two .NET and Oniguruma syntax items, and there are options for
- requesting some minor changes that give better ECMAScript (aka
- JavaScript) compatibility.
+ requesting some minor changes that give better ECMAScript (aka Java-
+ Script) compatibility.
The source code for PCRE2 can be compiled to support 8-bit, 16-bit, or
32-bit code units, which means that up to three separate libraries may
@@ -111,9 +111,9 @@
The use of the \C escape sequence in a UTF-8 or UTF-16 pattern can lead
to problems, because it may leave the current matching point in the
- middle of a multi-code-unit character. The PCRE2_NEVER_BACKSLASH_C
- option can be used by an application to lock out the use of \C, causing
- a compile-time error if it is encountered. It is also possible to build
+ middle of a multi-code-unit character. The PCRE2_NEVER_BACKSLASH_C op-
+ tion can be used by an application to lock out the use of \C, causing a
+ compile-time error if it is encountered. It is also possible to build
PCRE2 with the use of \C permanently disabled.
Another way that performance can be hit is by running a pattern that
@@ -451,8 +451,8 @@
void pcre2_converted_pattern_free(PCRE2_UCHAR *converted_pattern);
These functions provide a way of converting non-PCRE2 patterns into
- patterns that can be processed by pcre2_compile(). This facility is
- experimental and may be changed in future releases. At present, "globs"
+ patterns that can be processed by pcre2_compile(). This facility is ex-
+ perimental and may be changed in future releases. At present, "globs"
and POSIX basic and extended patterns can be converted. Details are
given in the pcre2convert documentation.
@@ -543,22 +543,22 @@
The compiling and matching functions recognize various options that are
passed as bits in an options argument. There are also some more compli-
- cated parameters such as custom memory management functions and
- resource limits that are passed in "contexts" (which are just memory
+ cated parameters such as custom memory management functions and re-
+ source limits that are passed in "contexts" (which are just memory
blocks, described below). Simple applications do not need to make use
of contexts.
Just-in-time (JIT) compiler support is an optional feature of PCRE2
that can be built in appropriate hardware environments. It greatly
- speeds up the matching performance of many patterns. Programs can
- request that it be used if available by calling pcre2_jit_compile()
- after a pattern has been successfully compiled by pcre2_compile(). This
- does nothing if JIT support is not available.
+ speeds up the matching performance of many patterns. Programs can re-
+ quest that it be used if available by calling pcre2_jit_compile() after
+ a pattern has been successfully compiled by pcre2_compile(). This does
+ nothing if JIT support is not available.
More complicated programs might need to make use of the specialist
functions pcre2_jit_stack_create(), pcre2_jit_stack_free(), and
- pcre2_jit_stack_assign() in order to control the JIT code's memory
- usage.
+ pcre2_jit_stack_assign() in order to control the JIT code's memory us-
+ age.
JIT matching is automatically used by pcre2_match() if it is available,
unless the PCRE2_NO_JIT option is set. There is also a direct interface
@@ -570,13 +570,12 @@
patible, is also provided. This uses a different algorithm for the
matching. The alternative algorithm finds all possible matches (at a
given point in the subject), and scans the subject just once (unless
- there are lookaround assertions). However, this algorithm does not
- return captured substrings. A description of the two matching algo-
- rithms and their advantages and disadvantages is given in the
- pcre2matching documentation. There is no JIT support for
- pcre2_dfa_match().
+ there are lookaround assertions). However, this algorithm does not re-
+ turn captured substrings. A description of the two matching algorithms
+ and their advantages and disadvantages is given in the pcre2matching
+ documentation. There is no JIT support for pcre2_dfa_match().
- In addition to the main compiling and matching functions, there are
+ In addition to the main compiling and matching functions, there are
convenience functions for extracting captured substrings from a subject
string that has been matched by pcre2_match(). They are:
@@ -590,35 +589,35 @@
pcre2_substring_nametable_scan()
pcre2_substring_number_from_name()
- pcre2_substring_free() and pcre2_substring_list_free() are also pro-
- vided, to free memory used for extracted strings. If either of these
- functions is called with a NULL argument, the function returns immedi-
+ pcre2_substring_free() and pcre2_substring_list_free() are also pro-
+ vided, to free memory used for extracted strings. If either of these
+ functions is called with a NULL argument, the function returns immedi-
ately without doing anything.
- The function pcre2_substitute() can be called to match a pattern and
- return a copy of the subject string with substitutions for parts that
+ The function pcre2_substitute() can be called to match a pattern and
+ return a copy of the subject string with substitutions for parts that
were matched.
- Functions whose names begin with pcre2_serialize_ are used for saving
+ Functions whose names begin with pcre2_serialize_ are used for saving
compiled patterns on disc or elsewhere, and reloading them later.
- Finally, there are functions for finding out information about a com-
- piled pattern (pcre2_pattern_info()) and about the configuration with
+ Finally, there are functions for finding out information about a com-
+ piled pattern (pcre2_pattern_info()) and about the configuration with
which PCRE2 was built (pcre2_config()).
- Functions with names ending with _free() are used for freeing memory
- blocks of various sorts. In all cases, if one of these functions is
+ Functions with names ending with _free() are used for freeing memory
+ blocks of various sorts. In all cases, if one of these functions is
called with a NULL argument, it does nothing.
STRING LENGTHS AND OFFSETS
- The PCRE2 API uses string lengths and offsets into strings of code
- units in several places. These values are always of type PCRE2_SIZE,
- which is an unsigned integer type, currently always defined as size_t.
- The largest value that can be stored in such a type (that is
- ~(PCRE2_SIZE)0) is reserved as a special indicator for zero-terminated
- strings and unset offsets. Therefore, the longest string that can be
+ The PCRE2 API uses string lengths and offsets into strings of code
+ units in several places. These values are always of type PCRE2_SIZE,
+ which is an unsigned integer type, currently always defined as size_t.
+ The largest value that can be stored in such a type (that is
+ ~(PCRE2_SIZE)0) is reserved as a special indicator for zero-terminated
+ strings and unset offsets. Therefore, the longest string that can be
handled is one less than this maximum.
@@ -625,31 +624,31 @@
NEWLINES
PCRE2 supports five different conventions for indicating line breaks in
- strings: a single CR (carriage return) character, a single LF (line-
+ strings: a single CR (carriage return) character, a single LF (line-
feed) character, the two-character sequence CRLF, any of the three pre-
- ceding, or any Unicode newline sequence. The Unicode newline sequences
- are the three just mentioned, plus the single characters VT (vertical
+ ceding, or any Unicode newline sequence. The Unicode newline sequences
+ are the three just mentioned, plus the single characters VT (vertical
tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line
separator, U+2028), and PS (paragraph separator, U+2029).
- Each of the first three conventions is used by at least one operating
+ Each of the first three conventions is used by at least one operating
system as its standard newline sequence. When PCRE2 is built, a default
can be specified. If it is not, the default is set to LF, which is the
- Unix standard. However, the newline convention can be changed by an
- application when calling pcre2_compile(), or it can be specified by
- special text at the start of the pattern itself; this overrides any
- other settings. See the pcre2pattern page for details of the special
- character sequences.
+ Unix standard. However, the newline convention can be changed by an ap-
+ plication when calling pcre2_compile(), or it can be specified by spe-
+ cial text at the start of the pattern itself; this overrides any other
+ settings. See the pcre2pattern page for details of the special charac-
+ ter sequences.
- In the PCRE2 documentation the word "newline" is used to mean "the
+ In the PCRE2 documentation the word "newline" is used to mean "the
character or pair of characters that indicate a line break". The choice
- of newline convention affects the handling of the dot, circumflex, and
+ of newline convention affects the handling of the dot, circumflex, and
dollar metacharacters, the handling of #-comments in /x mode, and, when
- CRLF is a recognized line ending sequence, the match position advance-
+ CRLF is a recognized line ending sequence, the match position advance-
ment for a non-anchored pattern. There is more detail about this in the
section on pcre2_match() options below.
- The choice of newline convention does not affect the interpretation of
+ The choice of newline convention does not affect the interpretation of
the \n or \r escape sequences, nor does it affect what \R matches; this
has its own separate convention.
@@ -656,12 +655,12 @@
MULTITHREADING
- In a multithreaded application it is important to keep thread-specific
- data separate from data that can be shared between threads. The PCRE2
- library code itself is thread-safe: it contains no static or global
- variables. The API is designed to be fairly simple for non-threaded
- applications while at the same time ensuring that multithreaded appli-
- cations can use it.
+ In a multithreaded application it is important to keep thread-specific
+ data separate from data that can be shared between threads. The PCRE2
+ library code itself is thread-safe: it contains no static or global
+ variables. The API is designed to be fairly simple for non-threaded ap-
+ plications while at the same time ensuring that multithreaded applica-
+ tions can use it.
There are several different blocks of data that are used to pass infor-
mation between the application and the PCRE2 libraries.
@@ -668,19 +667,19 @@
The compiled pattern
- A pointer to the compiled form of a pattern is returned to the user
+ A pointer to the compiled form of a pattern is returned to the user
when pcre2_compile() is successful. The data in the compiled pattern is
- fixed, and does not change when the pattern is matched. Therefore, it
- is thread-safe, that is, the same compiled pattern can be used by more
+ fixed, and does not change when the pattern is matched. Therefore, it
+ is thread-safe, that is, the same compiled pattern can be used by more
than one thread simultaneously. For example, an application can compile
all its patterns at the start, before forking off multiple threads that
- use them. However, if the just-in-time (JIT) optimization feature is
- being used, it needs separate memory stack areas for each thread. See
+ use them. However, if the just-in-time (JIT) optimization feature is
+ being used, it needs separate memory stack areas for each thread. See
the pcre2jit documentation for more details.
- In a more complicated situation, where patterns are compiled only when
- they are first needed, but are still shared between threads, pointers
- to compiled patterns must be protected from simultaneous writing by
+ In a more complicated situation, where patterns are compiled only when
+ they are first needed, but are still shared between threads, pointers
+ to compiled patterns must be protected from simultaneous writing by
multiple threads, at least until a pattern has been compiled. The logic
can be something like this:
@@ -693,65 +692,65 @@
Release the lock
Use pointer in pcre2_match()
- Of course, testing for compilation errors should also be included in
+ Of course, testing for compilation errors should also be included in
the code.
If JIT is being used, but the JIT compilation is not being done immedi-
- ately, (perhaps waiting to see if the pattern is used often enough)
+ ately, (perhaps waiting to see if the pattern is used often enough)
similar logic is required. JIT compilation updates a pointer within the
- compiled code block, so a thread must gain unique write access to the
- pointer before calling pcre2_jit_compile(). Alternatively,
- pcre2_code_copy() or pcre2_code_copy_with_tables() can be used to
- obtain a private copy of the compiled code before calling the JIT com-
+ compiled code block, so a thread must gain unique write access to the
+ pointer before calling pcre2_jit_compile(). Alternatively,
+ pcre2_code_copy() or pcre2_code_copy_with_tables() can be used to ob-
+ tain a private copy of the compiled code before calling the JIT com-
piler.
Context blocks
- The next main section below introduces the idea of "contexts" in which
+ The next main section below introduces the idea of "contexts" in which
PCRE2 functions are called. A context is nothing more than a collection
of parameters that control the way PCRE2 operates. Grouping a number of
parameters together in a context is a convenient way of passing them to
- a PCRE2 function without using lots of arguments. The parameters that
- are stored in contexts are in some sense "advanced features" of the
+ a PCRE2 function without using lots of arguments. The parameters that
+ are stored in contexts are in some sense "advanced features" of the
API. Many straightforward applications will not need to use contexts.
In a multithreaded application, if the parameters in a context are val-
- ues that are never changed, the same context can be used by all the
+ ues that are never changed, the same context can be used by all the
threads. However, if any thread needs to change any value in a context,
it must make its own thread-specific copy.
Match blocks
- The matching functions need a block of memory for storing the results
+ The matching functions need a block of memory for storing the results
of a match. This includes details of what was matched, as well as addi-
- tional information such as the name of a (*MARK) setting. Each thread
+ tional information such as the name of a (*MARK) setting. Each thread
must provide its own copy of this memory.
PCRE2 CONTEXTS
- Some PCRE2 functions have a lot of parameters, many of which are used
- only by specialist applications, for example, those that use custom
- memory management or non-standard character tables. To keep function
- argument lists at a reasonable size, and at the same time to keep the
- API extensible, "uncommon" parameters are passed to certain functions
- in a context instead of directly. A context is just a block of memory
- that holds the parameter values. Applications that do not need to
- adjust any of the context parameters can pass NULL when a context
- pointer is required.
+ Some PCRE2 functions have a lot of parameters, many of which are used
+ only by specialist applications, for example, those that use custom
+ memory management or non-standard character tables. To keep function
+ argument lists at a reasonable size, and at the same time to keep the
+ API extensible, "uncommon" parameters are passed to certain functions
+ in a context instead of directly. A context is just a block of memory
+ that holds the parameter values. Applications that do not need to ad-
+ just any of the context parameters can pass NULL when a context pointer
+ is required.
- There are three different types of context: a general context that is
- relevant for several PCRE2 operations, a compile-time context, and a
+ There are three different types of context: a general context that is
+ relevant for several PCRE2 operations, a compile-time context, and a
match-time context.
The general context
- At present, this context just contains pointers to (and data for)
- external memory management functions that are called from several
- places in the PCRE2 library. The context is named `general' rather than
- specifically `memory' because in future other fields may be added. If
- you do not want to supply your own custom memory management functions,
- you do not need to bother with a general context. A general context is
+ At present, this context just contains pointers to (and data for) ex-
+ ternal memory management functions that are called from several places
+ in the PCRE2 library. The context is named `general' rather than
+ specifically `memory' because in future other fields may be added. If
+ you do not want to supply your own custom memory management functions,
+ you do not need to bother with a general context. A general context is
created by:
pcre2_general_context *pcre2_general_context_create(
@@ -758,7 +757,7 @@
void *(*private_malloc)(PCRE2_SIZE, void *),
void (*private_free)(void *, void *), void *memory_data);
- The two function pointers specify custom memory management functions,
+ The two function pointers specify custom memory management functions,
whose prototypes are:
void *private_malloc(PCRE2_SIZE, void *);
@@ -766,16 +765,16 @@
Whenever code in PCRE2 calls these functions, the final argument is the
value of memory_data. Either of the first two arguments of the creation
- function may be NULL, in which case the system memory management func-
- tions malloc() and free() are used. (This is not currently useful, as
- there are no other fields in a general context, but in future there
- might be.) The private_malloc() function is used (if supplied) to
- obtain memory for storing the context, and all three values are saved
- as part of the context.
+ function may be NULL, in which case the system memory management func-
+ tions malloc() and free() are used. (This is not currently useful, as
+ there are no other fields in a general context, but in future there
+ might be.) The private_malloc() function is used (if supplied) to ob-
+ tain memory for storing the context, and all three values are saved as
+ part of the context.
- Whenever PCRE2 creates a data block of any kind, the block contains a
- pointer to the free() function that matches the malloc() function that
- was used. When the time comes to free the block, this function is
+ Whenever PCRE2 creates a data block of any kind, the block contains a
+ pointer to the free() function that matches the malloc() function that
+ was used. When the time comes to free the block, this function is
called.
A general context can be copied by calling:
@@ -787,13 +786,13 @@
void pcre2_general_context_free(pcre2_general_context *gcontext);
- If this function is passed a NULL argument, it returns immediately
+ If this function is passed a NULL argument, it returns immediately
without doing anything.
The compile context
- A compile context is required if you want to provide an external func-
- tion for stack checking during compilation or to change the default
+ A compile context is required if you want to provide an external func-
+ tion for stack checking during compilation or to change the default
values of any of the following compile-time parameters:
What \R matches (Unicode newlines or CR, LF, CRLF only)
@@ -803,11 +802,11 @@
The maximum length of the pattern string
The extra options bits (none set by default)
- A compile context is also required if you are using custom memory man-
- agement. If none of these apply, just pass NULL as the context argu-
+ A compile context is also required if you are using custom memory man-
+ agement. If none of these apply, just pass NULL as the context argu-
ment of pcre2_compile().
- A compile context is created, copied, and freed by the following func-
+ A compile context is created, copied, and freed by the following func-
tions:
pcre2_compile_context *pcre2_compile_context_create(
@@ -818,7 +817,7 @@
void pcre2_compile_context_free(pcre2_compile_context *ccontext);
- A compile context is created with default values for its parameters.
+ A compile context is created with default values for its parameters.
These can be changed by calling the following functions, which return 0
on success, or PCRE2_ERROR_BADDATA if invalid data is detected.
@@ -825,16 +824,16 @@
int pcre2_set_bsr(pcre2_compile_context *ccontext,
uint32_t value);
- The value must be PCRE2_BSR_ANYCRLF, to specify that \R matches only
- CR, LF, or CRLF, or PCRE2_BSR_UNICODE, to specify that \R matches any
+ The value must be PCRE2_BSR_ANYCRLF, to specify that \R matches only
+ CR, LF, or CRLF, or PCRE2_BSR_UNICODE, to specify that \R matches any
Unicode line ending sequence. The value is used by the JIT compiler and
- by the two interpreted matching functions, pcre2_match() and
+ by the two interpreted matching functions, pcre2_match() and
pcre2_dfa_match().
int pcre2_set_character_tables(pcre2_compile_context *ccontext,
const unsigned char *tables);
- The value must be the result of a call to pcre2_maketables(), whose
+ The value must be the result of a call to pcre2_maketables(), whose
only argument is a general context. This function builds a set of char-
acter tables in the current locale.
@@ -841,22 +840,22 @@
int pcre2_set_compile_extra_options(pcre2_compile_context *ccontext,
uint32_t extra_options);
- As PCRE2 has developed, almost all the 32 option bits that are avail-
- able in the options argument of pcre2_compile() have been used up. To
- avoid running out, the compile context contains a set of extra option
- bits which are used for some newer, assumed rarer, options. This func-
- tion sets those bits. It always sets all the bits (either on or off).
- It does not modify any existing setting. The available options are
- defined in the section entitled "Extra compile options" below.
+ As PCRE2 has developed, almost all the 32 option bits that are avail-
+ able in the options argument of pcre2_compile() have been used up. To
+ avoid running out, the compile context contains a set of extra option
+ bits which are used for some newer, assumed rarer, options. This func-
+ tion sets those bits. It always sets all the bits (either on or off).
+ It does not modify any existing setting. The available options are de-
+ fined in the section entitled "Extra compile options" below.
int pcre2_set_max_pattern_length(pcre2_compile_context *ccontext,
PCRE2_SIZE value);
- This sets a maximum length, in code units, for any pattern string that
- is compiled with this context. If the pattern is longer, an error is
- generated. This facility is provided so that applications that accept
+ This sets a maximum length, in code units, for any pattern string that
+ is compiled with this context. If the pattern is longer, an error is
+ generated. This facility is provided so that applications that accept
patterns from external sources can limit their size. The default is the
- largest number that a PCRE2_SIZE variable can hold, which is effec-
+ largest number that a PCRE2_SIZE variable can hold, which is effec-
tively unlimited.
int pcre2_set_newline(pcre2_compile_context *ccontext,
@@ -863,46 +862,46 @@
uint32_t value);
This specifies which characters or character sequences are to be recog-
- nized as newlines. The value must be one of PCRE2_NEWLINE_CR (carriage
+ nized as newlines. The value must be one of PCRE2_NEWLINE_CR (carriage
return only), PCRE2_NEWLINE_LF (linefeed only), PCRE2_NEWLINE_CRLF (the
- two-character sequence CR followed by LF), PCRE2_NEWLINE_ANYCRLF (any
- of the above), PCRE2_NEWLINE_ANY (any Unicode newline sequence), or
+ two-character sequence CR followed by LF), PCRE2_NEWLINE_ANYCRLF (any
+ of the above), PCRE2_NEWLINE_ANY (any Unicode newline sequence), or
PCRE2_NEWLINE_NUL (the NUL character, that is a binary zero).
A pattern can override the value set in the compile context by starting
with a sequence such as (*CRLF). See the pcre2pattern page for details.
- When a pattern is compiled with the PCRE2_EXTENDED or
- PCRE2_EXTENDED_MORE option, the newline convention affects the recogni-
- tion of the end of internal comments starting with #. The value is
- saved with the compiled pattern for subsequent use by the JIT compiler
- and by the two interpreted matching functions, pcre2_match() and
+ When a pattern is compiled with the PCRE2_EXTENDED or PCRE2_EX-
+ TENDED_MORE option, the newline convention affects the recognition of
+ the end of internal comments starting with #. The value is saved with
+ the compiled pattern for subsequent use by the JIT compiler and by the
+ two interpreted matching functions, pcre2_match() and
pcre2_dfa_match().
int pcre2_set_parens_nest_limit(pcre2_compile_context *ccontext,
uint32_t value);
- This parameter adjusts the limit, set when PCRE2 is built (default
- 250), on the depth of parenthesis nesting in a pattern. This limit
- stops rogue patterns using up too much system stack when being com-
- piled. The limit applies to parentheses of all kinds, not just captur-
+ This parameter adjusts the limit, set when PCRE2 is built (default
+ 250), on the depth of parenthesis nesting in a pattern. This limit
+ stops rogue patterns using up too much system stack when being com-
+ piled. The limit applies to parentheses of all kinds, not just captur-
ing parentheses.
int pcre2_set_compile_recursion_guard(pcre2_compile_context *ccontext,
int (*guard_function)(uint32_t, void *), void *user_data);
- There is at least one application that runs PCRE2 in threads with very
- limited system stack, where running out of stack is to be avoided at
- all costs. The parenthesis limit above cannot take account of how much
- stack is actually available during compilation. For a finer control,
- you can supply a function that is called whenever pcre2_compile()
- starts to compile a parenthesized part of a pattern. This function can
- check the actual stack size (or anything else that it wants to, of
+ There is at least one application that runs PCRE2 in threads with very
+ limited system stack, where running out of stack is to be avoided at
+ all costs. The parenthesis limit above cannot take account of how much
+ stack is actually available during compilation. For a finer control,
+ you can supply a function that is called whenever pcre2_compile()
+ starts to compile a parenthesized part of a pattern. This function can
+ check the actual stack size (or anything else that it wants to, of
course).
- The first argument to the callout function gives the current depth of
- nesting, and the second is user data that is set up by the last argu-
- ment of pcre2_set_compile_recursion_guard(). The callout function
+ The first argument to the callout function gives the current depth of
+ nesting, and the second is user data that is set up by the last argu-
+ ment of pcre2_set_compile_recursion_guard(). The callout function
should return zero if all is well, or non-zero to force an error.
The match context
@@ -916,10 +915,10 @@
Change the backtracking depth limit
Set custom memory management specifically for the match
- If none of these apply, just pass NULL as the context argument of
+ If none of these apply, just pass NULL as the context argument of
pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match().
- A match context is created, copied, and freed by the following func-
+ A match context is created, copied, and freed by the following func-
tions:
pcre2_match_context *pcre2_match_context_create(
@@ -930,7 +929,7 @@
void pcre2_match_context_free(pcre2_match_context *mcontext);
- A match context is created with default values for its parameters.
+ A match context is created with default values for its parameters.
These can be changed by calling the following functions, which return 0
on success, or PCRE2_ERROR_BADDATA if invalid data is detected.
@@ -938,7 +937,7 @@
int (*callout_function)(pcre2_callout_block *, void *),
void *callout_data);
- This sets up a callout function for PCRE2 to call at specified points
+ This sets up a callout function for PCRE2 to call at specified points
during a matching operation. Details are given in the pcre2callout doc-
umentation.
@@ -946,7 +945,7 @@
int (*callout_function)(pcre2_substitute_callout_block *, void *),
void *callout_data);
- This sets up a callout function for PCRE2 to call after each substitu-
+ This sets up a callout function for PCRE2 to call after each substitu-
tion made by pcre2_substitute(). Details are given in the section enti-
tled "Creating a new string with substitutions" below.
@@ -953,12 +952,11 @@
int pcre2_set_offset_limit(pcre2_match_context *mcontext,
PCRE2_SIZE value);
- The offset_limit parameter limits how far an unanchored search can
- advance in the subject string. The default value is PCRE2_UNSET. The
- pcre2_match() and pcre2_dfa_match() functions return
- PCRE2_ERROR_NOMATCH if a match with a starting point before or at the
- given offset is not found. The pcre2_substitute() function makes no
- more substitutions.
+ The offset_limit parameter limits how far an unanchored search can ad-
+ vance in the subject string. The default value is PCRE2_UNSET. The
+ pcre2_match() and pcre2_dfa_match() functions return PCRE2_ERROR_NO-
+ MATCH if a match with a starting point before or at the given offset is
+ not found. The pcre2_substitute() function makes no more substitutions.
For example, if the pattern /abc/ is matched against "123abc" with an
offset limit less than 3, the result is PCRE2_ERROR_NOMATCH. A match
@@ -966,16 +964,15 @@
pcre2_dfa_match(), or pcre2_substitute() is greater than the offset
limit set in the match context.
- When using this facility, you must set the PCRE2_USE_OFFSET_LIMIT
- option when calling pcre2_compile() so that when JIT is in use, differ-
- ent code can be compiled. If a match is started with a non-default
- match limit when PCRE2_USE_OFFSET_LIMIT is not set, an error is gener-
- ated.
+ When using this facility, you must set the PCRE2_USE_OFFSET_LIMIT op-
+ tion when calling pcre2_compile() so that when JIT is in use, different
+ code can be compiled. If a match is started with a non-default match
+ limit when PCRE2_USE_OFFSET_LIMIT is not set, an error is generated.
- The offset limit facility can be used to track progress when searching
- large subject strings or to limit the extent of global substitutions.
- See also the PCRE2_FIRSTLINE option, which requires a match to start
- before or at the first newline that follows the start of matching in
+ The offset limit facility can be used to track progress when searching
+ large subject strings or to limit the extent of global substitutions.
+ See also the PCRE2_FIRSTLINE option, which requires a match to start
+ before or at the first newline that follows the start of matching in
the subject. If this is set with an offset limit, a match must occur in
the first line and also within the offset limit. In other words, which-
ever limit comes first is used.
@@ -984,15 +981,15 @@
uint32_t value);
The heap_limit parameter specifies, in units of kibibytes (1024 bytes),
- the maximum amount of heap memory that pcre2_match() may use to hold
+ the maximum amount of heap memory that pcre2_match() may use to hold
backtracking information when running an interpretive match. This limit
also applies to pcre2_dfa_match(), which may use the heap when process-
- ing patterns with a lot of nested pattern recursion or lookarounds or
+ ing patterns with a lot of nested pattern recursion or lookarounds or
atomic groups. This limit does not apply to matching with the JIT opti-
- mization, which has its own memory control arrangements (see the
- pcre2jit documentation for more details). If the limit is reached, the
- negative error code PCRE2_ERROR_HEAPLIMIT is returned. The default
- limit can be set when PCRE2 is built; if it is not, the default is set
+ mization, which has its own memory control arrangements (see the
+ pcre2jit documentation for more details). If the limit is reached, the
+ negative error code PCRE2_ERROR_HEAPLIMIT is returned. The default
+ limit can be set when PCRE2 is built; if it is not, the default is set
very large and is essentially "unlimited".
A value for the heap limit may also be supplied by an item at the start
@@ -1000,101 +997,101 @@
(*LIMIT_HEAP=ddd)
- where ddd is a decimal number. However, such a setting is ignored
- unless ddd is less than the limit set by the caller of pcre2_match()
- or, if no such limit is set, less than the default.
+ where ddd is a decimal number. However, such a setting is ignored un-
+ less ddd is less than the limit set by the caller of pcre2_match() or,
+ if no such limit is set, less than the default.
- The pcre2_match() function starts out using a 20KiB vector on the sys-
+ The pcre2_match() function starts out using a 20KiB vector on the sys-
tem stack for recording backtracking points. The more nested backtrack-
- ing points there are (that is, the deeper the search tree), the more
- memory is needed. Heap memory is used only if the initial vector is
+ ing points there are (that is, the deeper the search tree), the more
+ memory is needed. Heap memory is used only if the initial vector is
too small. If the heap limit is set to a value less than 21 (in partic-
- ular, zero) no heap memory will be used. In this case, only patterns
- that do not have a lot of nested backtracking can be successfully pro-
+ ular, zero) no heap memory will be used. In this case, only patterns
+ that do not have a lot of nested backtracking can be successfully pro-
cessed.
- Similarly, for pcre2_dfa_match(), a vector on the system stack is used
- when processing pattern recursions, lookarounds, or atomic groups, and
- only if this is not big enough is heap memory used. In this case, too,
+ Similarly, for pcre2_dfa_match(), a vector on the system stack is used
+ when processing pattern recursions, lookarounds, or atomic groups, and
+ only if this is not big enough is heap memory used. In this case, too,
setting a value of zero disables the use of the heap.
int pcre2_set_match_limit(pcre2_match_context *mcontext,
uint32_t value);
- The match_limit parameter provides a means of preventing PCRE2 from
- using up too many computing resources when processing patterns that are
+ The match_limit parameter provides a means of preventing PCRE2 from us-
+ ing up too many computing resources when processing patterns that are
not going to match, but which have a very large number of possibilities
- in their search trees. The classic example is a pattern that uses
+ in their search trees. The classic example is a pattern that uses
nested unlimited repeats.
- There is an internal counter in pcre2_match() that is incremented each
- time round its main matching loop. If this value reaches the match
+ There is an internal counter in pcre2_match() that is incremented each
+ time round its main matching loop. If this value reaches the match
limit, pcre2_match() returns the negative value PCRE2_ERROR_MATCHLIMIT.
- This has the effect of limiting the amount of backtracking that can
+ This has the effect of limiting the amount of backtracking that can
take place. For patterns that are not anchored, the count restarts from
- zero for each position in the subject string. This limit also applies
+ zero for each position in the subject string. This limit also applies
to pcre2_dfa_match(), though the counting is done in a different way.
- When pcre2_match() is called with a pattern that was successfully pro-
+ When pcre2_match() is called with a pattern that was successfully pro-
cessed by pcre2_jit_compile(), the way in which matching is executed is
- entirely different. However, there is still the possibility of runaway
- matching that goes on for a very long time, and so the match_limit
- value is also used in this case (but in a different way) to limit how
+ entirely different. However, there is still the possibility of runaway
+ matching that goes on for a very long time, and so the match_limit
+ value is also used in this case (but in a different way) to limit how
long the matching can continue.
- The default value for the limit can be set when PCRE2 is built; the
- default default is 10 million, which handles all but the most extreme
- cases. A value for the match limit may also be supplied by an item at
+ The default value for the limit can be set when PCRE2 is built; the de-
+ fault default is 10 million, which handles all but the most extreme
+ cases. A value for the match limit may also be supplied by an item at
the start of a pattern of the form
(*LIMIT_MATCH=ddd)
- where ddd is a decimal number. However, such a setting is ignored
- unless ddd is less than the limit set by the caller of pcre2_match() or
+ where ddd is a decimal number. However, such a setting is ignored un-
+ less ddd is less than the limit set by the caller of pcre2_match() or
pcre2_dfa_match() or, if no such limit is set, less than the default.
int pcre2_set_depth_limit(pcre2_match_context *mcontext,
uint32_t value);
- This parameter limits the depth of nested backtracking in
- pcre2_match(). Each time a nested backtracking point is passed, a new
+ This parameter limits the depth of nested backtracking in
+ pcre2_match(). Each time a nested backtracking point is passed, a new
memory "frame" is used to remember the state of matching at that point.
- Thus, this parameter indirectly limits the amount of memory that is
- used in a match. However, because the size of each memory "frame"
- depends on the number of capturing parentheses, the actual memory limit
- varies from pattern to pattern. This limit was more useful in versions
+ Thus, this parameter indirectly limits the amount of memory that is
+ used in a match. However, because the size of each memory "frame" de-
+ pends on the number of capturing parentheses, the actual memory limit
+ varies from pattern to pattern. This limit was more useful in versions
before 10.30, where function recursion was used for backtracking.
- The depth limit is not relevant, and is ignored, when matching is done
+ The depth limit is not relevant, and is ignored, when matching is done
using JIT compiled code. However, it is supported by pcre2_dfa_match(),
- which uses it to limit the depth of nested internal recursive function
- calls that implement atomic groups, lookaround assertions, and pattern
+ which uses it to limit the depth of nested internal recursive function
+ calls that implement atomic groups, lookaround assertions, and pattern
recursions. This limits, indirectly, the amount of system stack that is
- used. It was more useful in versions before 10.32, when stack memory
+ used. It was more useful in versions before 10.32, when stack memory
was used for local workspace vectors for recursive function calls. From
- version 10.32, only local variables are allocated on the stack and as
+ version 10.32, only local variables are allocated on the stack and as
each call uses only a few hundred bytes, even a small stack can support
quite a lot of recursion.
- If the depth of internal recursive function calls is great enough,
- local workspace vectors are allocated on the heap from version 10.32
- onwards, so the depth limit also indirectly limits the amount of heap
+ If the depth of internal recursive function calls is great enough, lo-
+ cal workspace vectors are allocated on the heap from version 10.32 on-
+ wards, so the depth limit also indirectly limits the amount of heap
memory that is used. A recursive pattern such as /(.(?2))((?1)|)/, when
- matched to a very long string using pcre2_dfa_match(), can use a great
- deal of memory. However, it is probably better to limit heap usage
- directly by calling pcre2_set_heap_limit().
+ matched to a very long string using pcre2_dfa_match(), can use a great
+ deal of memory. However, it is probably better to limit heap usage di-
+ rectly by calling pcre2_set_heap_limit().
- The default value for the depth limit can be set when PCRE2 is built;
- if it is not, the default is set to the same value as the default for
- the match limit. If the limit is exceeded, pcre2_match() or
+ The default value for the depth limit can be set when PCRE2 is built;
+ if it is not, the default is set to the same value as the default for
+ the match limit. If the limit is exceeded, pcre2_match() or
pcre2_dfa_match() returns PCRE2_ERROR_DEPTHLIMIT. A value for the depth
- limit may also be supplied by an item at the start of a pattern of the
+ limit may also be supplied by an item at the start of a pattern of the
form
(*LIMIT_DEPTH=ddd)
- where ddd is a decimal number. However, such a setting is ignored
- unless ddd is less than the limit set by the caller of pcre2_match() or
+ where ddd is a decimal number. However, such a setting is ignored un-
+ less ddd is less than the limit set by the caller of pcre2_match() or
pcre2_dfa_match() or, if no such limit is set, less than the default.
@@ -1102,96 +1099,96 @@
int pcre2_config(uint32_t what, void *where);
- The function pcre2_config() makes it possible for a PCRE2 client to
- discover which optional features have been compiled into the PCRE2
- library. The pcre2build documentation has more details about these
- optional features.
+ The function pcre2_config() makes it possible for a PCRE2 client to
+ discover which optional features have been compiled into the PCRE2 li-
+ brary. The pcre2build documentation has more details about these op-
+ tional features.
- The first argument for pcre2_config() specifies which information is
- required. The second argument is a pointer to memory into which the
- information is placed. If NULL is passed, the function returns the
- amount of memory that is needed for the requested information. For
- calls that return numerical values, the value is in bytes; when
- requesting these values, where should point to appropriately aligned
- memory. For calls that return strings, the required length is given in
- code units, not counting the terminating zero.
+ The first argument for pcre2_config() specifies which information is
+ required. The second argument is a pointer to memory into which the in-
+ formation is placed. If NULL is passed, the function returns the amount
+ of memory that is needed for the requested information. For calls that
+ return numerical values, the value is in bytes; when requesting these
+ values, where should point to appropriately aligned memory. For calls
+ that return strings, the required length is given in code units, not
+ counting the terminating zero.
- When requesting information, the returned value from pcre2_config() is
- non-negative on success, or the negative error code PCRE2_ERROR_BADOP-
- TION if the value in the first argument is not recognized. The follow-
+ When requesting information, the returned value from pcre2_config() is
+ non-negative on success, or the negative error code PCRE2_ERROR_BADOP-
+ TION if the value in the first argument is not recognized. The follow-
ing information is available:
PCRE2_CONFIG_BSR
- The output is a uint32_t integer whose value indicates what character
- sequences the \R escape sequence matches by default. A value of
- PCRE2_BSR_UNICODE means that \R matches any Unicode line ending
- sequence; a value of PCRE2_BSR_ANYCRLF means that \R matches only CR,
- LF, or CRLF. The default can be overridden when a pattern is compiled.
+ The output is a uint32_t integer whose value indicates what character
+ sequences the \R escape sequence matches by default. A value of
+ PCRE2_BSR_UNICODE means that \R matches any Unicode line ending se-
+ quence; a value of PCRE2_BSR_ANYCRLF means that \R matches only CR, LF,
+ or CRLF. The default can be overridden when a pattern is compiled.
PCRE2_CONFIG_COMPILED_WIDTHS
- The output is a uint32_t integer whose lower bits indicate which code
- unit widths were selected when PCRE2 was built. The 1-bit indicates
- 8-bit support, and the 2-bit and 4-bit indicate 16-bit and 32-bit sup-
+ The output is a uint32_t integer whose lower bits indicate which code
+ unit widths were selected when PCRE2 was built. The 1-bit indicates
+ 8-bit support, and the 2-bit and 4-bit indicate 16-bit and 32-bit sup-
port, respectively.
PCRE2_CONFIG_DEPTHLIMIT
- The output is a uint32_t integer that gives the default limit for the
- depth of nested backtracking in pcre2_match() or the depth of nested
- recursions, lookarounds, and atomic groups in pcre2_dfa_match(). Fur-
+ The output is a uint32_t integer that gives the default limit for the
+ depth of nested backtracking in pcre2_match() or the depth of nested
+ recursions, lookarounds, and atomic groups in pcre2_dfa_match(). Fur-
ther details are given with pcre2_set_depth_limit() above.
PCRE2_CONFIG_HEAPLIMIT
- The output is a uint32_t integer that gives, in kibibytes, the default
- limit for the amount of heap memory used by pcre2_match() or
- pcre2_dfa_match(). Further details are given with
+ The output is a uint32_t integer that gives, in kibibytes, the default
+ limit for the amount of heap memory used by pcre2_match() or
+ pcre2_dfa_match(). Further details are given with
pcre2_set_heap_limit() above.
PCRE2_CONFIG_JIT
- The output is a uint32_t integer that is set to one if support for
+ The output is a uint32_t integer that is set to one if support for
just-in-time compiling is available; otherwise it is set to zero.
PCRE2_CONFIG_JITTARGET
- The where argument should point to a buffer that is at least 48 code
- units long. (The exact length required can be found by calling
- pcre2_config() with where set to NULL.) The buffer is filled with a
- string that contains the name of the architecture for which the JIT
- compiler is configured, for example "x86 32bit (little endian +
- unaligned)". If JIT support is not available, PCRE2_ERROR_BADOPTION is
- returned, otherwise the number of code units used is returned. This is
+ The where argument should point to a buffer that is at least 48 code
+ units long. (The exact length required can be found by calling
+ pcre2_config() with where set to NULL.) The buffer is filled with a
+ string that contains the name of the architecture for which the JIT
+ compiler is configured, for example "x86 32bit (little endian + un-
+ aligned)". If JIT support is not available, PCRE2_ERROR_BADOPTION is
+ returned, otherwise the number of code units used is returned. This is
the length of the string, plus one unit for the terminating zero.
PCRE2_CONFIG_LINKSIZE
The output is a uint32_t integer that contains the number of bytes used
- for internal linkage in compiled regular expressions. When PCRE2 is
- configured, the value can be set to 2, 3, or 4, with the default being
- 2. This is the value that is returned by pcre2_config(). However, when
- the 16-bit library is compiled, a value of 3 is rounded up to 4, and
- when the 32-bit library is compiled, internal linkages always use 4
+ for internal linkage in compiled regular expressions. When PCRE2 is
+ configured, the value can be set to 2, 3, or 4, with the default being
+ 2. This is the value that is returned by pcre2_config(). However, when
+ the 16-bit library is compiled, a value of 3 is rounded up to 4, and
+ when the 32-bit library is compiled, internal linkages always use 4
bytes, so the configured value is not relevant.
The default value of 2 for the 8-bit and 16-bit libraries is sufficient
- for all but the most massive patterns, since it allows the size of the
- compiled pattern to be up to 65535 code units. Larger values allow
- larger regular expressions to be compiled by those two libraries, but
+ for all but the most massive patterns, since it allows the size of the
+ compiled pattern to be up to 65535 code units. Larger values allow
+ larger regular expressions to be compiled by those two libraries, but
at the expense of slower matching.
PCRE2_CONFIG_MATCHLIMIT
The output is a uint32_t integer that gives the default match limit for
- pcre2_match(). Further details are given with pcre2_set_match_limit()
+ pcre2_match(). Further details are given with pcre2_set_match_limit()
above.
PCRE2_CONFIG_NEWLINE
- The output is a uint32_t integer whose value specifies the default
- character sequence that is recognized as meaning "newline". The values
+ The output is a uint32_t integer whose value specifies the default
+ character sequence that is recognized as meaning "newline". The values
are:
PCRE2_NEWLINE_CR Carriage return (CR)
@@ -1201,23 +1198,23 @@
PCRE2_NEWLINE_ANYCRLF Any of CR, LF, or CRLF
PCRE2_NEWLINE_NUL The NUL character (binary zero)
- The default should normally correspond to the standard sequence for
+ The default should normally correspond to the standard sequence for
your operating system.
PCRE2_CONFIG_NEVER_BACKSLASH_C
- The output is a uint32_t integer that is set to one if the use of \C
- was permanently disabled when PCRE2 was built; otherwise it is set to
+ The output is a uint32_t integer that is set to one if the use of \C
+ was permanently disabled when PCRE2 was built; otherwise it is set to
zero.
PCRE2_CONFIG_PARENSLIMIT
- The output is a uint32_t integer that gives the maximum depth of nest-
+ The output is a uint32_t integer that gives the maximum depth of nest-
ing of parentheses (of any kind) in a pattern. This limit is imposed to
- cap the amount of system stack used when a pattern is compiled. It is
- specified when PCRE2 is built; the default is 250. This limit does not
- take into account the stack that may already be used by the calling
- application. For finer control over compilation stack usage, see
+ cap the amount of system stack used when a pattern is compiled. It is
+ specified when PCRE2 is built; the default is 250. This limit does not
+ take into account the stack that may already be used by the calling ap-
+ plication. For finer control over compilation stack usage, see
pcre2_set_compile_recursion_guard().
PCRE2_CONFIG_STACKRECURSE
@@ -1227,25 +1224,25 @@
PCRE2_CONFIG_UNICODE_VERSION
- The where argument should point to a buffer that is at least 24 code
- units long. (The exact length required can be found by calling
- pcre2_config() with where set to NULL.) If PCRE2 has been compiled
- without Unicode support, the buffer is filled with the text "Unicode
- not supported". Otherwise, the Unicode version string (for example,
- "8.0.0") is inserted. The number of code units used is returned. This
+ The where argument should point to a buffer that is at least 24 code
+ units long. (The exact length required can be found by calling
+ pcre2_config() with where set to NULL.) If PCRE2 has been compiled
+ without Unicode support, the buffer is filled with the text "Unicode
+ not supported". Otherwise, the Unicode version string (for example,
+ "8.0.0") is inserted. The number of code units used is returned. This
is the length of the string plus one unit for the terminating zero.
PCRE2_CONFIG_UNICODE
- The output is a uint32_t integer that is set to one if Unicode support
- is available; otherwise it is set to zero. Unicode support implies UTF
+ The output is a uint32_t integer that is set to one if Unicode support
+ is available; otherwise it is set to zero. Unicode support implies UTF
support.
PCRE2_CONFIG_VERSION
- The where argument should point to a buffer that is at least 24 code
- units long. (The exact length required can be found by calling
- pcre2_config() with where set to NULL.) The buffer is filled with the
+ The where argument should point to a buffer that is at least 24 code
+ units long. (The exact length required can be found by calling
+ pcre2_config() with where set to NULL.) The buffer is filled with the
PCRE2 version string, zero-terminated. The number of code units used is
returned. This is the length of the string plus one unit for the termi-
nating zero.
@@ -1263,103 +1260,103 @@
pcre2_code *pcre2_code_copy_with_tables(const pcre2_code *code);
- The pcre2_compile() function compiles a pattern into an internal form.
- The pattern is defined by a pointer to a string of code units and a
- length (in code units). If the pattern is zero-terminated, the length
- can be specified as PCRE2_ZERO_TERMINATED. The function returns a
- pointer to a block of memory that contains the compiled pattern and
- related data, or NULL if an error occurred.
+ The pcre2_compile() function compiles a pattern into an internal form.
+ The pattern is defined by a pointer to a string of code units and a
+ length (in code units). If the pattern is zero-terminated, the length
+ can be specified as PCRE2_ZERO_TERMINATED. The function returns a
+ pointer to a block of memory that contains the compiled pattern and re-
+ lated data, or NULL if an error occurred.
- If the compile context argument ccontext is NULL, memory for the com-
- piled pattern is obtained by calling malloc(). Otherwise, it is
- obtained from the same memory function that was used for the compile
- context. The caller must free the memory by calling pcre2_code_free()
- when it is no longer needed. If pcre2_code_free() is called with a
- NULL argument, it returns immediately, without doing anything.
+ If the compile context argument ccontext is NULL, memory for the com-
+ piled pattern is obtained by calling malloc(). Otherwise, it is ob-
+ tained from the same memory function that was used for the compile con-
+ text. The caller must free the memory by calling pcre2_code_free() when
+ it is no longer needed. If pcre2_code_free() is called with a NULL ar-
+ gument, it returns immediately, without doing anything.
The function pcre2_code_copy() makes a copy of the compiled code in new
- memory, using the same memory allocator as was used for the original.
- However, if the code has been processed by the JIT compiler (see
- below), the JIT information cannot be copied (because it is position-
- dependent). The new copy can initially be used only for non-JIT match-
- ing, though it can be passed to pcre2_jit_compile() if required. If
+ memory, using the same memory allocator as was used for the original.
+ However, if the code has been processed by the JIT compiler (see be-
+ low), the JIT information cannot be copied (because it is position-de-
+ pendent). The new copy can initially be used only for non-JIT match-
+ ing, though it can be passed to pcre2_jit_compile() if required. If
pcre2_code_copy() is called with a NULL argument, it returns NULL.
The pcre2_code_copy() function provides a way for individual threads in
- a multithreaded application to acquire a private copy of shared com-
- piled code. However, it does not make a copy of the character tables
- used by the compiled pattern; the new pattern code points to the same
- tables as the original code. (See "Locale Support" below for details
- of these character tables.) In many applications the same tables are
- used throughout, so this behaviour is appropriate. Nevertheless, there
+ a multithreaded application to acquire a private copy of shared com-
+ piled code. However, it does not make a copy of the character tables
+ used by the compiled pattern; the new pattern code points to the same
+ tables as the original code. (See "Locale Support" below for details
+ of these character tables.) In many applications the same tables are
+ used throughout, so this behaviour is appropriate. Nevertheless, there
are occasions when a copy of a compiled pattern and the relevant tables
- are needed. The pcre2_code_copy_with_tables() provides this facility.
- Copies of both the code and the tables are made, with the new code
- pointing to the new tables. The memory for the new tables is automati-
- cally freed when pcre2_code_free() is called for the new copy of the
- compiled code. If pcre2_code_copy_with_tables() is called with a NULL
+ are needed. The pcre2_code_copy_with_tables() provides this facility.
+ Copies of both the code and the tables are made, with the new code
+ pointing to the new tables. The memory for the new tables is automati-
+ cally freed when pcre2_code_free() is called for the new copy of the
+ compiled code. If pcre2_code_copy_with_tables() is called with a NULL
argument, it returns NULL.
- NOTE: When one of the matching functions is called, pointers to the
+ NOTE: When one of the matching functions is called, pointers to the
compiled pattern and the subject string are set in the match data block
- so that they can be referenced by the substring extraction functions
- after a successful match. After running a match, you must not free a
- compiled pattern or a subject string until after all operations on the
- match data block have taken place, unless, in the case of the subject
- string, you have used the PCRE2_COPY_MATCHED_SUBJECT option, which is
- described in the section entitled "Option bits for pcre2_match()"
- below.
+ so that they can be referenced by the substring extraction functions
+ after a successful match. After running a match, you must not free a
+ compiled pattern or a subject string until after all operations on the
+ match data block have taken place, unless, in the case of the subject
+ string, you have used the PCRE2_COPY_MATCHED_SUBJECT option, which is
+ described in the section entitled "Option bits for pcre2_match()" be-
+ low.
- The options argument for pcre2_compile() contains various bit settings
- that affect the compilation. It should be zero if none of them are
- required. The available options are described below. Some of them (in
- particular, those that are compatible with Perl, but some others as
- well) can also be set and unset from within the pattern (see the
- detailed description in the pcre2pattern documentation).
+ The options argument for pcre2_compile() contains various bit settings
+ that affect the compilation. It should be zero if none of them are re-
+ quired. The available options are described below. Some of them (in
+ particular, those that are compatible with Perl, but some others as
+ well) can also be set and unset from within the pattern (see the de-
+ tailed description in the pcre2pattern documentation).
- For those options that can be different in different parts of the pat-
- tern, the contents of the options argument specifies their settings at
- the start of compilation. The PCRE2_ANCHORED, PCRE2_ENDANCHORED, and
- PCRE2_NO_UTF_CHECK options can be set at the time of matching as well
+ For those options that can be different in different parts of the pat-
+ tern, the contents of the options argument specifies their settings at
+ the start of compilation. The PCRE2_ANCHORED, PCRE2_ENDANCHORED, and
+ PCRE2_NO_UTF_CHECK options can be set at the time of matching as well
as at compile time.
- Some additional options and less frequently required compile-time
- parameters (for example, the newline setting) can be provided in a com-
+ Some additional options and less frequently required compile-time pa-
+ rameters (for example, the newline setting) can be provided in a com-
pile context (as described above).
If errorcode or erroroffset is NULL, pcre2_compile() returns NULL imme-
- diately. Otherwise, the variables to which these point are set to an
- error code and an offset (number of code units) within the pattern,
- respectively, when pcre2_compile() returns NULL because a compilation
- error has occurred. The values are not defined when compilation is suc-
+ diately. Otherwise, the variables to which these point are set to an
+ error code and an offset (number of code units) within the pattern, re-
+ spectively, when pcre2_compile() returns NULL because a compilation er-
+ ror has occurred. The values are not defined when compilation is suc-
cessful and pcre2_compile() returns a non-NULL value.
- There are nearly 100 positive error codes that pcre2_compile() may
- return if it finds an error in the pattern. There are also some nega-
- tive error codes that are used for invalid UTF strings when validity
- checking is in force. These are the same as given by pcre2_match() and
+ There are nearly 100 positive error codes that pcre2_compile() may re-
+ turn if it finds an error in the pattern. There are also some negative
+ error codes that are used for invalid UTF strings when validity check-
+ ing is in force. These are the same as given by pcre2_match() and
pcre2_dfa_match(), and are described in the pcre2unicode documentation.
- There is no separate documentation for the positive error codes,
- because the textual error messages that are obtained by calling the
+ There is no separate documentation for the positive error codes, be-
+ cause the textual error messages that are obtained by calling the
pcre2_get_error_message() function (see "Obtaining a textual error mes-
- sage" below) should be self-explanatory. Macro names starting with
- PCRE2_ERROR_ are defined for both positive and negative error codes in
+ sage" below) should be self-explanatory. Macro names starting with
+ PCRE2_ERROR_ are defined for both positive and negative error codes in
pcre2.h.
The value returned in erroroffset is an indication of where in the pat-
- tern the error occurred. It is not necessarily the furthest point in
- the pattern that was read. For example, after the error "lookbehind
- assertion is not fixed length", the error offset points to the start of
- the failing assertion. For an invalid UTF-8 or UTF-16 string, the off-
+ tern the error occurred. It is not necessarily the furthest point in
+ the pattern that was read. For example, after the error "lookbehind as-
+ sertion is not fixed length", the error offset points to the start of
+ the failing assertion. For an invalid UTF-8 or UTF-16 string, the off-
set is that of the first code unit of the failing character.
- Some errors are not detected until the whole pattern has been scanned;
- in these cases, the offset passed back is the length of the pattern.
- Note that the offset is in code units, not characters, even in a UTF
+ Some errors are not detected until the whole pattern has been scanned;
+ in these cases, the offset passed back is the length of the pattern.
+ Note that the offset is in code units, not characters, even in a UTF
mode. It may sometimes point into the middle of a UTF-8 or UTF-16 char-
acter.
- This code fragment shows a typical straightforward call to pcre2_com-
+ This code fragment shows a typical straightforward call to pcre2_com-
pile():
pcre2_code *re;
@@ -1376,28 +1373,28 @@
Main compile options
- The following names for option bits are defined in the pcre2.h header
+ The following names for option bits are defined in the pcre2.h header
file:
PCRE2_ANCHORED
If this bit is set, the pattern is forced to be "anchored", that is, it
- is constrained to match only at the first matching point in the string
- that is being searched (the "subject string"). This effect can also be
- achieved by appropriate constructs in the pattern itself, which is the
+ is constrained to match only at the first matching point in the string
+ that is being searched (the "subject string"). This effect can also be
+ achieved by appropriate constructs in the pattern itself, which is the
only way to do it in Perl.
PCRE2_ALLOW_EMPTY_CLASS
- By default, for compatibility with Perl, a closing square bracket that
- immediately follows an opening one is treated as a data character for
- the class. When PCRE2_ALLOW_EMPTY_CLASS is set, it terminates the
+ By default, for compatibility with Perl, a closing square bracket that
+ immediately follows an opening one is treated as a data character for
+ the class. When PCRE2_ALLOW_EMPTY_CLASS is set, it terminates the
class, which therefore contains no characters and so can never match.
PCRE2_ALT_BSUX
- This option request alternative handling of three escape sequences,
- which makes PCRE2's behaviour more like ECMAscript (aka JavaScript).
+ This option request alternative handling of three escape sequences,
+ which makes PCRE2's behaviour more like ECMAscript (aka JavaScript).
When it is set:
(1) \U matches an upper case "U" character; by default \U causes a com-
@@ -1404,129 +1401,128 @@
pile time error (Perl uses \U to upper case subsequent characters).
(2) \u matches a lower case "u" character unless it is followed by four
- hexadecimal digits, in which case the hexadecimal number defines the
- code point to match. By default, \u causes a compile time error (Perl
+ hexadecimal digits, in which case the hexadecimal number defines the
+ code point to match. By default, \u causes a compile time error (Perl
uses it to upper case the following character).
- (3) \x matches a lower case "x" character unless it is followed by two
- hexadecimal digits, in which case the hexadecimal number defines the
- code point to match. By default, as in Perl, a hexadecimal number is
+ (3) \x matches a lower case "x" character unless it is followed by two
+ hexadecimal digits, in which case the hexadecimal number defines the
+ code point to match. By default, as in Perl, a hexadecimal number is
always expected after \x, but it may have zero, one, or two digits (so,
for example, \xz matches a binary zero character followed by z).
ECMAscript 6 added additional functionality to \u. This can be accessed
- using the PCRE2_EXTRA_ALT_BSUX extra option (see "Extra compile
- options" below). Note that this alternative escape handling applies
- only to patterns. Neither of these options affects the processing of
- replacement strings passed to pcre2_substitute().
+ using the PCRE2_EXTRA_ALT_BSUX extra option (see "Extra compile op-
+ tions" below). Note that this alternative escape handling applies only
+ to patterns. Neither of these options affects the processing of re-
+ placement strings passed to pcre2_substitute().
PCRE2_ALT_CIRCUMFLEX
In multiline mode (when PCRE2_MULTILINE is set), the circumflex
- metacharacter matches at the start of the subject (unless PCRE2_NOTBOL
- is set), and also after any internal newline. However, it does not
+ metacharacter matches at the start of the subject (unless PCRE2_NOTBOL
+ is set), and also after any internal newline. However, it does not
match after a newline at the end of the subject, for compatibility with
- Perl. If you want a multiline circumflex also to match after a termi-
+ Perl. If you want a multiline circumflex also to match after a termi-
nating newline, you must set PCRE2_ALT_CIRCUMFLEX.
PCRE2_ALT_VERBNAMES
- By default, for compatibility with Perl, the name in any verb sequence
- such as (*MARK:NAME) is any sequence of characters that does not
- include a closing parenthesis. The name is not processed in any way,
- and it is not possible to include a closing parenthesis in the name.
- However, if the PCRE2_ALT_VERBNAMES option is set, normal backslash
- processing is applied to verb names and only an unescaped closing
- parenthesis terminates the name. A closing parenthesis can be included
- in a name either as \) or between \Q and \E. If the PCRE2_EXTENDED or
- PCRE2_EXTENDED_MORE option is set with PCRE2_ALT_VERBNAMES, unescaped
- whitespace in verb names is skipped and #-comments are recognized,
- exactly as in the rest of the pattern.
+ By default, for compatibility with Perl, the name in any verb sequence
+ such as (*MARK:NAME) is any sequence of characters that does not in-
+ clude a closing parenthesis. The name is not processed in any way, and
+ it is not possible to include a closing parenthesis in the name. How-
+ ever, if the PCRE2_ALT_VERBNAMES option is set, normal backslash pro-
+ cessing is applied to verb names and only an unescaped closing paren-
+ thesis terminates the name. A closing parenthesis can be included in a
+ name either as \) or between \Q and \E. If the PCRE2_EXTENDED or
+ PCRE2_EXTENDED_MORE option is set with PCRE2_ALT_VERBNAMES, unescaped
+ whitespace in verb names is skipped and #-comments are recognized, ex-
+ actly as in the rest of the pattern.
PCRE2_AUTO_CALLOUT
- If this bit is set, pcre2_compile() automatically inserts callout
- items, all with number 255, before each pattern item, except immedi-
- ately before or after an explicit callout in the pattern. For discus-
+ If this bit is set, pcre2_compile() automatically inserts callout
+ items, all with number 255, before each pattern item, except immedi-
+ ately before or after an explicit callout in the pattern. For discus-
sion of the callout facility, see the pcre2callout documentation.
PCRE2_CASELESS
- If this bit is set, letters in the pattern match both upper and lower
- case letters in the subject. It is equivalent to Perl's /i option, and
- it can be changed within a pattern by a (?i) option setting. If
- PCRE2_UTF is set, Unicode properties are used for all characters with
- more than one other case, and for all characters whose code points are
- greater than U+007F. For lower valued characters with only one other
- case, a lookup table is used for speed. When PCRE2_UTF is not set, a
+ If this bit is set, letters in the pattern match both upper and lower
+ case letters in the subject. It is equivalent to Perl's /i option, and
+ it can be changed within a pattern by a (?i) option setting. If
+ PCRE2_UTF is set, Unicode properties are used for all characters with
+ more than one other case, and for all characters whose code points are
+ greater than U+007F. For lower valued characters with only one other
+ case, a lookup table is used for speed. When PCRE2_UTF is not set, a
lookup table is used for all code points less than 256, and higher code
- points (available only in 16-bit or 32-bit mode) are treated as not
+ points (available only in 16-bit or 32-bit mode) are treated as not
having another case.
PCRE2_DOLLAR_ENDONLY
- If this bit is set, a dollar metacharacter in the pattern matches only
- at the end of the subject string. Without this option, a dollar also
- matches immediately before a newline at the end of the string (but not
- before any other newlines). The PCRE2_DOLLAR_ENDONLY option is ignored
- if PCRE2_MULTILINE is set. There is no equivalent to this option in
+ If this bit is set, a dollar metacharacter in the pattern matches only
+ at the end of the subject string. Without this option, a dollar also
+ matches immediately before a newline at the end of the string (but not
+ before any other newlines). The PCRE2_DOLLAR_ENDONLY option is ignored
+ if PCRE2_MULTILINE is set. There is no equivalent to this option in
Perl, and no way to set it within a pattern.
PCRE2_DOTALL
- If this bit is set, a dot metacharacter in the pattern matches any
- character, including one that indicates a newline. However, it only
+ If this bit is set, a dot metacharacter in the pattern matches any
+ character, including one that indicates a newline. However, it only
ever matches one character, even if newlines are coded as CRLF. Without
this option, a dot does not match when the current position in the sub-
- ject is at a newline. This option is equivalent to Perl's /s option,
+ ject is at a newline. This option is equivalent to Perl's /s option,
and it can be changed within a pattern by a (?s) option setting. A neg-
- ative class such as [^a] always matches newline characters, and the \N
- escape sequence always matches a non-newline character, independent of
+ ative class such as [^a] always matches newline characters, and the \N
+ escape sequence always matches a non-newline character, independent of
the setting of PCRE2_DOTALL.
PCRE2_DUPNAMES
- If this bit is set, names used to identify capture groups need not be
- unique. This can be helpful for certain types of pattern when it is
- known that only one instance of the named group can ever be matched.
- There are more details of named capture groups below; see also the
+ If this bit is set, names used to identify capture groups need not be
+ unique. This can be helpful for certain types of pattern when it is
+ known that only one instance of the named group can ever be matched.
+ There are more details of named capture groups below; see also the
pcre2pattern documentation.
PCRE2_ENDANCHORED
- If this bit is set, the end of any pattern match must be right at the
+ If this bit is set, the end of any pattern match must be right at the
end of the string being searched (the "subject string"). If the pattern
match succeeds by reaching (*ACCEPT), but does not reach the end of the
- subject, the match fails at the current starting point. For unanchored
- patterns, a new match is then tried at the next starting point. How-
+ subject, the match fails at the current starting point. For unanchored
+ patterns, a new match is then tried at the next starting point. How-
ever, if the match succeeds by reaching the end of the pattern, but not
- the end of the subject, backtracking occurs and an alternative match
+ the end of the subject, backtracking occurs and an alternative match
may be found. Consider these two patterns:
.(*ACCEPT)|..
.|..
- If matched against "abc" with PCRE2_ENDANCHORED set, the first matches
- "c" whereas the second matches "bc". The effect of PCRE2_ENDANCHORED
- can also be achieved by appropriate constructs in the pattern itself,
+ If matched against "abc" with PCRE2_ENDANCHORED set, the first matches
+ "c" whereas the second matches "bc". The effect of PCRE2_ENDANCHORED
+ can also be achieved by appropriate constructs in the pattern itself,
which is the only way to do it in Perl.
For DFA matching with pcre2_dfa_match(), PCRE2_ENDANCHORED applies only
- to the first (that is, the longest) matched string. Other parallel
- matches, which are necessarily substrings of the first one, must obvi-
+ to the first (that is, the longest) matched string. Other parallel
+ matches, which are necessarily substrings of the first one, must obvi-
ously end before the end of the subject.
PCRE2_EXTENDED
- If this bit is set, most white space characters in the pattern are
- totally ignored except when escaped or inside a character class. How-
- ever, white space is not allowed within sequences such as (?> that
- introduce various parenthesized groups, nor within numerical quanti-
- fiers such as {1,3}. Ignorable white space is permitted between an item
- and a following quantifier and between a quantifier and a following +
- that indicates possessiveness. PCRE2_EXTENDED is equivalent to Perl's
- /x option, and it can be changed within a pattern by a (?x) option set-
- ting.
+ If this bit is set, most white space characters in the pattern are to-
+ tally ignored except when escaped or inside a character class. However,
+ white space is not allowed within sequences such as (?> that introduce
+ various parenthesized groups, nor within numerical quantifiers such as
+ {1,3}. Ignorable white space is permitted between an item and a follow-
+ ing quantifier and between a quantifier and a following + that indi-
+ cates possessiveness. PCRE2_EXTENDED is equivalent to Perl's /x option,
+ and it can be changed within a pattern by a (?x) option setting.
When PCRE2 is compiled without Unicode support, PCRE2_EXTENDED recog-
nizes as white space only those characters with code points less than
@@ -1561,90 +1557,88 @@
PCRE2_EXTENDED_MORE
- This option has the effect of PCRE2_EXTENDED, but, in addition,
- unescaped space and horizontal tab characters are ignored inside a
- character class. Note: only these two characters are ignored, not the
- full set of pattern white space characters that are ignored outside a
- character class. PCRE2_EXTENDED_MORE is equivalent to Perl's /xx
- option, and it can be changed within a pattern by a (?xx) option set-
- ting.
+ This option has the effect of PCRE2_EXTENDED, but, in addition, un-
+ escaped space and horizontal tab characters are ignored inside a char-
+ acter class. Note: only these two characters are ignored, not the full
+ set of pattern white space characters that are ignored outside a char-
+ acter class. PCRE2_EXTENDED_MORE is equivalent to Perl's /xx option,
+ and it can be changed within a pattern by a (?xx) option setting.
PCRE2_FIRSTLINE
If this option is set, the start of an unanchored pattern match must be
- before or at the first newline in the subject string following the
- start of matching, though the matched text may continue over the new-
+ before or at the first newline in the subject string following the
+ start of matching, though the matched text may continue over the new-
line. If startoffset is non-zero, the limiting newline is not necessar-
- ily the first newline in the subject. For example, if the subject
+ ily the first newline in the subject. For example, if the subject
string is "abc\nxyz" (where \n represents a single-character newline) a
- pattern match for "yz" succeeds with PCRE2_FIRSTLINE if startoffset is
- greater than 3. See also PCRE2_USE_OFFSET_LIMIT, which provides a more
- general limiting facility. If PCRE2_FIRSTLINE is set with an offset
- limit, a match must occur in the first line and also within the offset
+ pattern match for "yz" succeeds with PCRE2_FIRSTLINE if startoffset is
+ greater than 3. See also PCRE2_USE_OFFSET_LIMIT, which provides a more
+ general limiting facility. If PCRE2_FIRSTLINE is set with an offset
+ limit, a match must occur in the first line and also within the offset
limit. In other words, whichever limit comes first is used.
PCRE2_LITERAL
If this option is set, all meta-characters in the pattern are disabled,
- and it is treated as a literal string. Matching literal strings with a
+ and it is treated as a literal string. Matching literal strings with a
regular expression engine is not the most efficient way of doing it. If
- you are doing a lot of literal matching and are worried about effi-
+ you are doing a lot of literal matching and are worried about effi-
ciency, you should consider using other approaches. The only other main
options that are allowed with PCRE2_LITERAL are: PCRE2_ANCHORED,
PCRE2_ENDANCHORED, PCRE2_AUTO_CALLOUT, PCRE2_CASELESS, PCRE2_FIRSTLINE,
PCRE2_MATCH_INVALID_UTF, PCRE2_NO_START_OPTIMIZE, PCRE2_NO_UTF_CHECK,
- PCRE2_UTF, and PCRE2_USE_OFFSET_LIMIT. The extra options
- PCRE2_EXTRA_MATCH_LINE and PCRE2_EXTRA_MATCH_WORD are also supported.
- Any other options cause an error.
+ PCRE2_UTF, and PCRE2_USE_OFFSET_LIMIT. The extra options PCRE2_EX-
+ TRA_MATCH_LINE and PCRE2_EXTRA_MATCH_WORD are also supported. Any other
+ options cause an error.
PCRE2_MATCH_INVALID_UTF
- This option forces PCRE2_UTF (see below) and also enables support for
- matching by pcre2_match() in subject strings that contain invalid UTF
- sequences. This facility is not supported for DFA matching. For
- details, see the pcre2unicode documentation.
+ This option forces PCRE2_UTF (see below) and also enables support for
+ matching by pcre2_match() in subject strings that contain invalid UTF
+ sequences. This facility is not supported for DFA matching. For de-
+ tails, see the pcre2unicode documentation.
PCRE2_MATCH_UNSET_BACKREF
- If this option is set, a backreference to an unset capture group
- matches an empty string (by default this causes the current matching
- alternative to fail). A pattern such as (\1)(a) succeeds when this
- option is set (assuming it can find an "a" in the subject), whereas it
- fails by default, for Perl compatibility. Setting this option makes
+ If this option is set, a backreference to an unset capture group
+ matches an empty string (by default this causes the current matching
+ alternative to fail). A pattern such as (\1)(a) succeeds when this op-
+ tion is set (assuming it can find an "a" in the subject), whereas it
+ fails by default, for Perl compatibility. Setting this option makes
PCRE2 behave more like ECMAscript (aka JavaScript).
PCRE2_MULTILINE
- By default, for the purposes of matching "start of line" and "end of
- line", PCRE2 treats the subject string as consisting of a single line
- of characters, even if it actually contains newlines. The "start of
- line" metacharacter (^) matches only at the start of the string, and
- the "end of line" metacharacter ($) matches only at the end of the
- string, or before a terminating newline (except when PCRE2_DOL-
- LAR_ENDONLY is set). Note, however, that unless PCRE2_DOTALL is set,
- the "any character" metacharacter (.) does not match at a newline. This
- behaviour (for ^, $, and dot) is the same as Perl.
+ By default, for the purposes of matching "start of line" and "end of
+ line", PCRE2 treats the subject string as consisting of a single line
+ of characters, even if it actually contains newlines. The "start of
+ line" metacharacter (^) matches only at the start of the string, and
+ the "end of line" metacharacter ($) matches only at the end of the
+ string, or before a terminating newline (except when PCRE2_DOLLAR_EN-
+ DONLY is set). Note, however, that unless PCRE2_DOTALL is set, the "any
+ character" metacharacter (.) does not match at a newline. This behav-
+ iour (for ^, $, and dot) is the same as Perl.
- When PCRE2_MULTILINE it is set, the "start of line" and "end of line"
- constructs match immediately following or immediately before internal
- newlines in the subject string, respectively, as well as at the very
- start and end. This is equivalent to Perl's /m option, and it can be
+ When PCRE2_MULTILINE it is set, the "start of line" and "end of line"
+ constructs match immediately following or immediately before internal
+ newlines in the subject string, respectively, as well as at the very
+ start and end. This is equivalent to Perl's /m option, and it can be
changed within a pattern by a (?m) option setting. Note that the "start
of line" metacharacter does not match after a newline at the end of the
- subject, for compatibility with Perl. However, you can change this by
- setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a
- subject string, or no occurrences of ^ or $ in a pattern, setting
+ subject, for compatibility with Perl. However, you can change this by
+ setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a
+ subject string, or no occurrences of ^ or $ in a pattern, setting
PCRE2_MULTILINE has no effect.
PCRE2_NEVER_BACKSLASH_C
- This option locks out the use of \C in the pattern that is being com-
- piled. This escape can cause unpredictable behaviour in UTF-8 or
- UTF-16 modes, because it may leave the current matching point in the
- middle of a multi-code-unit character. This option may be useful in
- applications that process patterns from external sources. Note that
- there is also a build-time option that permanently locks out the use of
- \C.
+ This option locks out the use of \C in the pattern that is being com-
+ piled. This escape can cause unpredictable behaviour in UTF-8 or
+ UTF-16 modes, because it may leave the current matching point in the
+ middle of a multi-code-unit character. This option may be useful in ap-
+ plications that process patterns from external sources. Note that there
+ is also a build-time option that permanently locks out the use of \C.
PCRE2_NEVER_UCP
@@ -1661,9 +1655,9 @@
This option locks out interpretation of the pattern as UTF-8, UTF-16,
or UTF-32, depending on which library is in use. In particular, it pre-
vents the creator of the pattern from switching to UTF interpretation
- by starting the pattern with (*UTF). This option may be useful in
- applications that process patterns from external sources. The combina-
- tion of PCRE2_UTF and PCRE2_NEVER_UTF causes an error.
+ by starting the pattern with (*UTF). This option may be useful in ap-
+ plications that process patterns from external sources. The combination
+ of PCRE2_UTF and PCRE2_NEVER_UTF causes an error.
PCRE2_NO_AUTO_CAPTURE
@@ -1738,8 +1732,8 @@
does. However, if the same match is run with PCRE2_NO_START_OPTIMIZE
set, the initial scan along the subject string does not happen. The
first match attempt is run starting from "D" and when this fails,
- (*COMMIT) prevents any further matches being tried, so the overall
- result is "no match".
+ (*COMMIT) prevents any further matches being tried, so the overall re-
+ sult is "no match".
As another start-up optimization makes use of a minimum length for a
matching subject, which is recorded when possible. Consider the pattern
@@ -1750,8 +1744,8 @@
"XXBB", the "starting character" optimization skips "XX", then tries to
match "BB", which is long enough. In the process, (*MARK:2) is encoun-
tered and remembered. When the match attempt fails, the next "B" is
- found, but there is only one character left, so there are no more
- attempts, and "no match" is returned with the "last mark seen" set to
+ found, but there is only one character left, so there are no more at-
+ tempts, and "no match" is returned with the "last mark seen" set to
"2". If NO_START_OPTIMIZE is set, however, matches are tried at every
possible starting position, including at the end of the subject, where
(*MARK:1) is encountered, but there is no "B", so the "last mark seen"
@@ -1769,8 +1763,8 @@
If you know that your pattern is a valid UTF string, and you want to
skip this check for performance reasons, you can set the
- PCRE2_NO_UTF_CHECK option. When it is set, the effect of passing an
- invalid UTF string as a pattern is undefined. It may cause your program
+ PCRE2_NO_UTF_CHECK option. When it is set, the effect of passing an in-
+ valid UTF string as a pattern is undefined. It may cause your program
to crash or loop.
Note that this option can also be passed to pcre2_match() and
@@ -1810,8 +1804,8 @@
This option must be set for pcre2_compile() if pcre2_set_offset_limit()
is going to be used to set a non-default offset limit in a match con-
text for matches that use this pattern. An error is generated if an
- offset limit is set without this option. For more details, see the
- description of pcre2_set_offset_limit() in the section that describes
+ offset limit is set without this option. For more details, see the de-
+ scription of pcre2_set_offset_limit() in the section that describes
match contexts. See also the PCRE2_FIRSTLINE option above.
PCRE2_UTF
@@ -1820,9 +1814,9 @@
strings that are subsequently processed as strings of UTF characters
instead of single-code-unit strings. It is available when PCRE2 is
built to include Unicode support (which is the default). If Unicode
- support is not available, the use of this option provokes an error.
- Details of how PCRE2_UTF changes the behaviour of PCRE2 are given in
- the pcre2unicode page. In particular, note that it changes the way
+ support is not available, the use of this option provokes an error. De-
+ tails of how PCRE2_UTF changes the behaviour of PCRE2 are given in the
+ pcre2unicode page. In particular, note that it changes the way
PCRE2_CASELESS handles characters with code points greater than 127.
Extra compile options
@@ -1843,74 +1837,73 @@
These values also cause errors if encountered in escape sequences such
as \x{d912} within a pattern. However, it seems that some applications,
- when using PCRE2 to check for unwanted characters in UTF-8 strings,
- explicitly test for the surrogates using escape sequences. The
- PCRE2_NO_UTF_CHECK option does not disable the error that occurs,
- because it applies only to the testing of input strings for UTF valid-
- ity.
+ when using PCRE2 to check for unwanted characters in UTF-8 strings, ex-
+ plicitly test for the surrogates using escape sequences. The
+ PCRE2_NO_UTF_CHECK option does not disable the error that occurs, be-
+ cause it applies only to the testing of input strings for UTF validity.
- If the extra option PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is set, surro-
- gate code point values in UTF-8 and UTF-32 patterns no longer provoke
- errors and are incorporated in the compiled pattern. However, they can
- only match subject characters if the matching function is called with
+ If the extra option PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is set, surro-
+ gate code point values in UTF-8 and UTF-32 patterns no longer provoke
+ errors and are incorporated in the compiled pattern. However, they can
+ only match subject characters if the matching function is called with
PCRE2_NO_UTF_CHECK set.
PCRE2_EXTRA_ALT_BSUX
- The original option PCRE2_ALT_BSUX causes PCRE2 to process \U, \u, and
- \x in the way that ECMAscript (aka JavaScript) does. Additional func-
+ The original option PCRE2_ALT_BSUX causes PCRE2 to process \U, \u, and
+ \x in the way that ECMAscript (aka JavaScript) does. Additional func-
tionality was defined by ECMAscript 6; setting PCRE2_EXTRA_ALT_BSUX has
- the effect of PCRE2_ALT_BSUX, but in addition it recognizes \u{hhh..}
+ the effect of PCRE2_ALT_BSUX, but in addition it recognizes \u{hhh..}
as a hexadecimal character code, where hhh.. is any number of hexadeci-
mal digits.
PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL
- This is a dangerous option. Use with care. By default, an unrecognized
- escape such as \j or a malformed one such as \x{2z} causes a compile-
+ This is a dangerous option. Use with care. By default, an unrecognized
+ escape such as \j or a malformed one such as \x{2z} causes a compile-
time error when detected by pcre2_compile(). Perl is somewhat inconsis-
- tent in handling such items: for example, \j is treated as a literal
- "j", and non-hexadecimal digits in \x{} are just ignored, though warn-
- ings are given in both cases if Perl's warning switch is enabled. How-
- ever, a malformed octal number after \o{ always causes an error in
+ tent in handling such items: for example, \j is treated as a literal
+ "j", and non-hexadecimal digits in \x{} are just ignored, though warn-
+ ings are given in both cases if Perl's warning switch is enabled. How-
+ ever, a malformed octal number after \o{ always causes an error in
Perl.
- If the PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL extra option is passed to
- pcre2_compile(), all unrecognized or malformed escape sequences are
- treated as single-character escapes. For example, \j is a literal "j"
- and \x{2z} is treated as the literal string "x{2z}". Setting this
- option means that typos in patterns may go undetected and have unex-
- pected results. Also note that a sequence such as [\N{] is interpreted
- as a malformed attempt at [\N{...}] and so is treated as [N{] whereas
- [\N] gives an error because an unqualified \N is a valid escape
- sequence but is not supported in a character class. To reiterate: this
- is a dangerous option. Use with great care.
+ If the PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL extra option is passed to
+ pcre2_compile(), all unrecognized or malformed escape sequences are
+ treated as single-character escapes. For example, \j is a literal "j"
+ and \x{2z} is treated as the literal string "x{2z}". Setting this op-
+ tion means that typos in patterns may go undetected and have unexpected
+ results. Also note that a sequence such as [\N{] is interpreted as a
+ malformed attempt at [\N{...}] and so is treated as [N{] whereas [\N]
+ gives an error because an unqualified \N is a valid escape sequence but
+ is not supported in a character class. To reiterate: this is a danger-
+ ous option. Use with great care.
PCRE2_EXTRA_ESCAPED_CR_IS_LF
- There are some legacy applications where the escape sequence \r in a
- pattern is expected to match a newline. If this option is set, \r in a
- pattern is converted to \n so that it matches a LF (linefeed) instead
- of a CR (carriage return) character. The option does not affect a lit-
- eral CR in the pattern, nor does it affect CR specified as an explicit
+ There are some legacy applications where the escape sequence \r in a
+ pattern is expected to match a newline. If this option is set, \r in a
+ pattern is converted to \n so that it matches a LF (linefeed) instead
+ of a CR (carriage return) character. The option does not affect a lit-
+ eral CR in the pattern, nor does it affect CR specified as an explicit
code point such as \x{0D}.
PCRE2_EXTRA_MATCH_LINE
- This option is provided for use by the -x option of pcre2grep. It
- causes the pattern only to match complete lines. This is achieved by
- automatically inserting the code for "^(?:" at the start of the com-
- piled pattern and ")$" at the end. Thus, when PCRE2_MULTILINE is set,
- the matched line may be in the middle of the subject string. This
- option can be used with PCRE2_LITERAL.
+ This option is provided for use by the -x option of pcre2grep. It
+ causes the pattern only to match complete lines. This is achieved by
+ automatically inserting the code for "^(?:" at the start of the com-
+ piled pattern and ")$" at the end. Thus, when PCRE2_MULTILINE is set,
+ the matched line may be in the middle of the subject string. This op-
+ tion can be used with PCRE2_LITERAL.
PCRE2_EXTRA_MATCH_WORD
- This option is provided for use by the -w option of pcre2grep. It
- causes the pattern only to match strings that have a word boundary at
- the start and the end. This is achieved by automatically inserting the
- code for "\b(?:" at the start of the compiled pattern and ")\b" at the
- end. The option may be used with PCRE2_LITERAL. However, it is ignored
+ This option is provided for use by the -w option of pcre2grep. It
+ causes the pattern only to match strings that have a word boundary at
+ the start and the end. This is achieved by automatically inserting the
+ code for "\b(?:" at the start of the compiled pattern and ")\b" at the
+ end. The option may be used with PCRE2_LITERAL. However, it is ignored
if PCRE2_EXTRA_MATCH_LINE is also set.
@@ -1933,53 +1926,53 @@
void pcre2_jit_stack_free(pcre2_jit_stack *jit_stack);
- These functions provide support for JIT compilation, which, if the
- just-in-time compiler is available, further processes a compiled pat-
+ These functions provide support for JIT compilation, which, if the
+ just-in-time compiler is available, further processes a compiled pat-
tern into machine code that executes much faster than the pcre2_match()
- interpretive matching function. Full details are given in the pcre2jit
+ interpretive matching function. Full details are given in the pcre2jit
documentation.
- JIT compilation is a heavyweight optimization. It can take some time
- for patterns to be analyzed, and for one-off matches and simple pat-
- terns the benefit of faster execution might be offset by a much slower
- compilation time. Most (but not all) patterns can be optimized by the
+ JIT compilation is a heavyweight optimization. It can take some time
+ for patterns to be analyzed, and for one-off matches and simple pat-
+ terns the benefit of faster execution might be offset by a much slower
+ compilation time. Most (but not all) patterns can be optimized by the
JIT compiler.
LOCALE SUPPORT
- PCRE2 handles caseless matching, and determines whether characters are
- letters, digits, or whatever, by reference to a set of tables, indexed
- by character code point. This applies only to characters whose code
- points are less than 256. By default, higher-valued code points never
- match escapes such as \w or \d. However, if PCRE2 is built with Uni-
+ PCRE2 handles caseless matching, and determines whether characters are
+ letters, digits, or whatever, by reference to a set of tables, indexed
+ by character code point. This applies only to characters whose code
+ points are less than 256. By default, higher-valued code points never
+ match escapes such as \w or \d. However, if PCRE2 is built with Uni-
code support, all characters can be tested with \p and \P, or, alterna-
- tively, the PCRE2_UCP option can be set when a pattern is compiled;
- this causes \w and friends to use Unicode property support instead of
+ tively, the PCRE2_UCP option can be set when a pattern is compiled;
+ this causes \w and friends to use Unicode property support instead of
the built-in tables.
- The use of locales with Unicode is discouraged. If you are handling
- characters with code points greater than 128, you should either use
+ The use of locales with Unicode is discouraged. If you are handling
+ characters with code points greater than 128, you should either use
Unicode support, or use locales, but not try to mix the two.
- PCRE2 contains an internal set of character tables that are used by
- default. These are sufficient for many applications. Normally, the
- internal tables recognize only ASCII characters. However, when PCRE2 is
+ PCRE2 contains an internal set of character tables that are used by de-
+ fault. These are sufficient for many applications. Normally, the in-
+ ternal tables recognize only ASCII characters. However, when PCRE2 is
built, it is possible to cause the internal tables to be rebuilt in the
default "C" locale of the local system, which may cause them to be dif-
ferent.
- The internal tables can be overridden by tables supplied by the appli-
- cation that calls PCRE2. These may be created in a different locale
- from the default. As more and more applications change to using Uni-
+ The internal tables can be overridden by tables supplied by the appli-
+ cation that calls PCRE2. These may be created in a different locale
+ from the default. As more and more applications change to using Uni-
code, the need for this locale support is expected to die away.
- External tables are built by calling the pcre2_maketables() function,
- in the relevant locale. The result can be passed to pcre2_compile() as
- often as necessary, by creating a compile context and calling
- pcre2_set_character_tables() to set the tables pointer therein. For
- example, to build and use tables that are appropriate for the French
- locale (where accented characters with values greater than 128 are
+ External tables are built by calling the pcre2_maketables() function,
+ in the relevant locale. The result can be passed to pcre2_compile() as
+ often as necessary, by creating a compile context and calling
+ pcre2_set_character_tables() to set the tables pointer therein. For ex-
+ ample, to build and use tables that are appropriate for the French lo-
+ cale (where accented characters with values greater than 128 are
treated as letters), the following code could be used:
setlocale(LC_CTYPE, "fr_FR");
@@ -1988,15 +1981,15 @@
pcre2_set_character_tables(ccontext, tables);
re = pcre2_compile(..., ccontext);
- The locale name "fr_FR" is used on Linux and other Unix-like systems;
- if you are using Windows, the name for the French locale is "french".
- It is the caller's responsibility to ensure that the memory containing
+ The locale name "fr_FR" is used on Linux and other Unix-like systems;
+ if you are using Windows, the name for the French locale is "french".
+ It is the caller's responsibility to ensure that the memory containing
the tables remains available for as long as it is needed.
The pointer that is passed (via the compile context) to pcre2_compile()
- is saved with the compiled pattern, and the same tables are used by
- pcre2_match() and pcre_dfa_match(). Thus, for any single pattern, com-
- pilation and matching both happen in the same locale, but different
+ is saved with the compiled pattern, and the same tables are used by
+ pcre2_match() and pcre_dfa_match(). Thus, for any single pattern, com-
+ pilation and matching both happen in the same locale, but different
patterns can be processed in different locales.
@@ -2004,13 +1997,13 @@
int pcre2_pattern_info(const pcre2 *code, uint32_t what, void *where);
- The pcre2_pattern_info() function returns general information about a
+ The pcre2_pattern_info() function returns general information about a
compiled pattern. For information about callouts, see the next section.
- The first argument for pcre2_pattern_info() is a pointer to the com-
+ The first argument for pcre2_pattern_info() is a pointer to the com-
piled pattern. The second argument specifies which piece of information
- is required, and the third argument is a pointer to a variable to
- receive the data. If the third argument is NULL, the first argument is
- ignored, and the function returns the size in bytes of the variable
+ is required, and the third argument is a pointer to a variable to re-
+ ceive the data. If the third argument is NULL, the first argument is
+ ignored, and the function returns the size in bytes of the variable
that is required for the information requested. Otherwise, the yield of
the function is zero for success, or one of the following negative num-
bers:
@@ -2020,9 +2013,9 @@
PCRE2_ERROR_BADOPTION the value of what was invalid
PCRE2_ERROR_UNSET the requested field is not set
- The "magic number" is placed at the start of each compiled pattern as
- an simple check against passing an arbitrary memory pointer. Here is a
- typical call of pcre2_pattern_info(), to obtain the length of the com-
+ The "magic number" is placed at the start of each compiled pattern as
+ an simple check against passing an arbitrary memory pointer. Here is a
+ typical call of pcre2_pattern_info(), to obtain the length of the com-
piled pattern:
int rc;
@@ -2040,22 +2033,22 @@
PCRE2_INFO_EXTRAOPTIONS
Return copies of the pattern's options. The third argument should point
- to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the
- options that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP-
- TIONS returns the compile options as modified by any top-level (*XXX)
- option settings such as (*UTF) at the start of the pattern itself.
- PCRE2_INFO_EXTRAOPTIONS returns the extra options that were set in the
- compile context by calling the pcre2_set_compile_extra_options() func-
+ to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the op-
+ tions that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP-
+ TIONS returns the compile options as modified by any top-level (*XXX)
+ option settings such as (*UTF) at the start of the pattern itself.
+ PCRE2_INFO_EXTRAOPTIONS returns the extra options that were set in the
+ compile context by calling the pcre2_set_compile_extra_options() func-
tion.
- For example, if the pattern /(*UTF)abc/ is compiled with the
- PCRE2_EXTENDED option, the result for PCRE2_INFO_ALLOPTIONS is
- PCRE2_EXTENDED and PCRE2_UTF. Option settings such as (?i) that can
- change within a pattern do not affect the result of PCRE2_INFO_ALLOP-
- TIONS, even if they appear right at the start of the pattern. (This was
- different in some earlier releases.)
+ For example, if the pattern /(*UTF)abc/ is compiled with the PCRE2_EX-
+ TENDED option, the result for PCRE2_INFO_ALLOPTIONS is PCRE2_EXTENDED
+ and PCRE2_UTF. Option settings such as (?i) that can change within a
+ pattern do not affect the result of PCRE2_INFO_ALLOPTIONS, even if they
+ appear right at the start of the pattern. (This was different in some
+ earlier releases.)
- A pattern compiled without PCRE2_ANCHORED is automatically anchored by
+ A pattern compiled without PCRE2_ANCHORED is automatically anchored by
PCRE2 if the first significant item in every top-level branch is one of
the following:
@@ -2064,7 +2057,7 @@
\G always
.* sometimes - see below
- When .* is the first significant item, anchoring is possible only when
+ When .* is the first significant item, anchoring is possible only when
all the following are true:
.* is not in an atomic group
@@ -2074,15 +2067,15 @@
Neither (*PRUNE) nor (*SKIP) appears in the pattern
PCRE2_NO_DOTSTAR_ANCHOR is not set
- For patterns that are auto-anchored, the PCRE2_ANCHORED bit is set in
+ For patterns that are auto-anchored, the PCRE2_ANCHORED bit is set in
the options returned for PCRE2_INFO_ALLOPTIONS.
PCRE2_INFO_BACKREFMAX
- Return the number of the highest backreference in the pattern. The
- third argument should point to an uint32_t variable. Named capture
- groups acquire numbers as well as names, and these count towards the
- highest backreference. Backreferences such as \4 or \g{12} match the
+ Return the number of the highest backreference in the pattern. The
+ third argument should point to an uint32_t variable. Named capture
+ groups acquire numbers as well as names, and these count towards the
+ highest backreference. Backreferences such as \4 or \g{12} match the
captured characters of the given group, but in addition, the check that
a capture group is set in a conditional group such as (?(3)a|b) is also
a backreference. Zero is returned if there are no backreferences.
@@ -2089,56 +2082,56 @@
PCRE2_INFO_BSR
- The output is a uint32_t integer whose value indicates what character
- sequences the \R escape sequence matches. A value of PCRE2_BSR_UNICODE
- means that \R matches any Unicode line ending sequence; a value of
+ The output is a uint32_t integer whose value indicates what character
+ sequences the \R escape sequence matches. A value of PCRE2_BSR_UNICODE
+ means that \R matches any Unicode line ending sequence; a value of
PCRE2_BSR_ANYCRLF means that \R matches only CR, LF, or CRLF.
PCRE2_INFO_CAPTURECOUNT
- Return the highest capture group number in the pattern. In patterns
+ Return the highest capture group number in the pattern. In patterns
where (?| is not used, this is also the total number of capture groups.
The third argument should point to an uint32_t variable.
PCRE2_INFO_DEPTHLIMIT
- If the pattern set a backtracking depth limit by including an item of
- the form (*LIMIT_DEPTH=nnnn) at the start, the value is returned. The
+ If the pattern set a backtracking depth limit by including an item of
+ the form (*LIMIT_DEPTH=nnnn) at the start, the value is returned. The
third argument should point to a uint32_t integer. If no such value has
- been set, the call to pcre2_pattern_info() returns the error
- PCRE2_ERROR_UNSET. Note that this limit will only be used during match-
- ing if it is less than the limit set or defaulted by the caller of the
- match function.
+ been set, the call to pcre2_pattern_info() returns the error PCRE2_ER-
+ ROR_UNSET. Note that this limit will only be used during matching if it
+ is less than the limit set or defaulted by the caller of the match
+ function.
PCRE2_INFO_FIRSTBITMAP
- In the absence of a single first code unit for a non-anchored pattern,
- pcre2_compile() may construct a 256-bit table that defines a fixed set
- of values for the first code unit in any match. For example, a pattern
- that starts with [abc] results in a table with three bits set. When
- code unit values greater than 255 are supported, the flag bit for 255
- means "any code unit of value 255 or above". If such a table was con-
- structed, a pointer to it is returned. Otherwise NULL is returned. The
+ In the absence of a single first code unit for a non-anchored pattern,
+ pcre2_compile() may construct a 256-bit table that defines a fixed set
+ of values for the first code unit in any match. For example, a pattern
+ that starts with [abc] results in a table with three bits set. When
+ code unit values greater than 255 are supported, the flag bit for 255
+ means "any code unit of value 255 or above". If such a table was con-
+ structed, a pointer to it is returned. Otherwise NULL is returned. The
third argument should point to a const uint8_t * variable.
PCRE2_INFO_FIRSTCODETYPE
Return information about the first code unit of any matched string, for
- a non-anchored pattern. The third argument should point to an uint32_t
- variable. If there is a fixed first value, for example, the letter "c"
- from a pattern such as (cat|cow|coyote), 1 is returned, and the value
- can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed
- first value, but it is known that a match can occur only at the start
- of the subject or following a newline in the subject, 2 is returned.
+ a non-anchored pattern. The third argument should point to an uint32_t
+ variable. If there is a fixed first value, for example, the letter "c"
+ from a pattern such as (cat|cow|coyote), 1 is returned, and the value
+ can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed
+ first value, but it is known that a match can occur only at the start
+ of the subject or following a newline in the subject, 2 is returned.
Otherwise, and for anchored patterns, 0 is returned.
PCRE2_INFO_FIRSTCODEUNIT
- Return the value of the first code unit of any matched string for a
- pattern where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0.
- The third argument should point to an uint32_t variable. In the 8-bit
- library, the value is always less than 256. In the 16-bit library the
- value can be up to 0xffff. In the 32-bit library in UTF-32 mode the
+ Return the value of the first code unit of any matched string for a
+ pattern where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0.
+ The third argument should point to an uint32_t variable. In the 8-bit
+ library, the value is always less than 256. In the 16-bit library the
+ value can be up to 0xffff. In the 32-bit library in UTF-32 mode the
value can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32
mode.
@@ -2145,8 +2138,8 @@
PCRE2_INFO_FRAMESIZE
Return the size (in bytes) of the data frames that are used to remember
- backtracking positions when the pattern is processed by pcre2_match()
- without the use of JIT. The third argument should point to a size_t
+ backtracking positions when the pattern is processed by pcre2_match()
+ without the use of JIT. The third argument should point to a size_t
variable. The frame size depends on the number of capturing parentheses
in the pattern. Each additional capture group adds two PCRE2_SIZE vari-
ables.
@@ -2153,16 +2146,16 @@
PCRE2_INFO_HASBACKSLASHC
- Return 1 if the pattern contains any instances of \C, otherwise 0. The
+ Return 1 if the pattern contains any instances of \C, otherwise 0. The
third argument should point to an uint32_t variable.
PCRE2_INFO_HASCRORLF
- Return 1 if the pattern contains any explicit matches for CR or LF
+ Return 1 if the pattern contains any explicit matches for CR or LF
characters, otherwise 0. The third argument should point to an uint32_t
- variable. An explicit match is either a literal CR or LF character, or
- \r or \n or one of the equivalent hexadecimal or octal escape
- sequences.
+ variable. An explicit match is either a literal CR or LF character, or
+ \r or \n or one of the equivalent hexadecimal or octal escape se-
+ quences.
PCRE2_INFO_HEAPLIMIT
@@ -2169,82 +2162,82 @@
If the pattern set a heap memory limit by including an item of the form
(*LIMIT_HEAP=nnnn) at the start, the value is returned. The third argu-
ment should point to a uint32_t integer. If no such value has been set,
- the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET.
- Note that this limit will only be used during matching if it is less
+ the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET.
+ Note that this limit will only be used during matching if it is less
than the limit set or defaulted by the caller of the match function.
PCRE2_INFO_JCHANGED
- Return 1 if the (?J) or (?-J) option setting is used in the pattern,
- otherwise 0. The third argument should point to an uint32_t variable.
- (?J) and (?-J) set and unset the local PCRE2_DUPNAMES option, respec-
+ Return 1 if the (?J) or (?-J) option setting is used in the pattern,
+ otherwise 0. The third argument should point to an uint32_t variable.
+ (?J) and (?-J) set and unset the local PCRE2_DUPNAMES option, respec-
tively.
PCRE2_INFO_JITSIZE
- If the compiled pattern was successfully processed by pcre2_jit_com-
- pile(), return the size of the JIT compiled code, otherwise return
+ If the compiled pattern was successfully processed by pcre2_jit_com-
+ pile(), return the size of the JIT compiled code, otherwise return
zero. The third argument should point to a size_t variable.
PCRE2_INFO_LASTCODETYPE
- Returns 1 if there is a rightmost literal code unit that must exist in
- any matched string, other than at its start. The third argument should
- point to an uint32_t variable. If there is no such value, 0 is
- returned. When 1 is returned, the code unit value itself can be
- retrieved using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last
- literal value is recorded only if it follows something of variable
- length. For example, for the pattern /^a\d+z\d+/ the returned value is
- 1 (with "z" returned from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/
- the returned value is 0.
+ Returns 1 if there is a rightmost literal code unit that must exist in
+ any matched string, other than at its start. The third argument should
+ point to an uint32_t variable. If there is no such value, 0 is re-
+ turned. When 1 is returned, the code unit value itself can be retrieved
+ using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last literal
+ value is recorded only if it follows something of variable length. For
+ example, for the pattern /^a\d+z\d+/ the returned value is 1 (with "z"
+ returned from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/ the returned
+ value is 0.
PCRE2_INFO_LASTCODEUNIT
- Return the value of the rightmost literal code unit that must exist in
- any matched string, other than at its start, for a pattern where
+ Return the value of the rightmost literal code unit that must exist in
+ any matched string, other than at its start, for a pattern where
PCRE2_INFO_LASTCODETYPE returns 1. Otherwise, return 0. The third argu-
ment should point to an uint32_t variable.
PCRE2_INFO_MATCHEMPTY
- Return 1 if the pattern might match an empty string, otherwise 0. The
- third argument should point to an uint32_t variable. When a pattern
+ Return 1 if the pattern might match an empty string, otherwise 0. The
+ third argument should point to an uint32_t variable. When a pattern
contains recursive subroutine calls it is not always possible to deter-
- mine whether or not it can match an empty string. PCRE2 takes a cau-
+ mine whether or not it can match an empty string. PCRE2 takes a cau-
tious approach and returns 1 in such cases.
PCRE2_INFO_MATCHLIMIT
- If the pattern set a match limit by including an item of the form
- (*LIMIT_MATCH=nnnn) at the start, the value is returned. The third
- argument should point to a uint32_t integer. If no such value has been
- set, the call to pcre2_pattern_info() returns the error
- PCRE2_ERROR_UNSET. Note that this limit will only be used during match-
- ing if it is less than the limit set or defaulted by the caller of the
- match function.
+ If the pattern set a match limit by including an item of the form
+ (*LIMIT_MATCH=nnnn) at the start, the value is returned. The third ar-
+ gument should point to a uint32_t integer. If no such value has been
+ set, the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UN-
+ SET. Note that this limit will only be used during matching if it is
+ less than the limit set or defaulted by the caller of the match func-
+ tion.
PCRE2_INFO_MAXLOOKBEHIND
Return the number of characters (not code units) in the longest lookbe-
- hind assertion in the pattern. The third argument should point to a
- uint32_t integer. This information is useful when doing multi-segment
- matching using the partial matching facilities. Note that the simple
+ hind assertion in the pattern. The third argument should point to a
+ uint32_t integer. This information is useful when doing multi-segment
+ matching using the partial matching facilities. Note that the simple
assertions \b and \B require a one-character lookbehind. \A also regis-
- ters a one-character lookbehind, though it does not actually inspect
- the previous character. This is to ensure that at least one character
- from the old segment is retained when a new segment is processed. Oth-
- erwise, if there are no lookbehinds in the pattern, \A might match
- incorrectly at the start of a second or subsequent segment.
+ ters a one-character lookbehind, though it does not actually inspect
+ the previous character. This is to ensure that at least one character
+ from the old segment is retained when a new segment is processed. Oth-
+ erwise, if there are no lookbehinds in the pattern, \A might match in-
+ correctly at the start of a second or subsequent segment.
PCRE2_INFO_MINLENGTH
- If a minimum length for matching subject strings was computed, its
+ If a minimum length for matching subject strings was computed, its
value is returned. Otherwise the returned value is 0. This value is not
- computed when PCRE2_NO_START_OPTIMIZE is set. The value is a number of
- characters, which in UTF mode may be different from the number of code
- units. The third argument should point to an uint32_t variable. The
- value is a lower bound to the length of any matching string. There may
- not be any strings of that length that do actually match, but every
+ computed when PCRE2_NO_START_OPTIMIZE is set. The value is a number of
+ characters, which in UTF mode may be different from the number of code
+ units. The third argument should point to an uint32_t variable. The
+ value is a lower bound to the length of any matching string. There may
+ not be any strings of that length that do actually match, but every
string that does match is at least that long.
PCRE2_INFO_NAMECOUNT
@@ -2252,44 +2245,44 @@
PCRE2_INFO_NAMETABLE
PCRE2 supports the use of named as well as numbered capturing parenthe-
- ses. The names are just an additional way of identifying the parenthe-
+ ses. The names are just an additional way of identifying the parenthe-
ses, which still acquire numbers. Several convenience functions such as
- pcre2_substring_get_byname() are provided for extracting captured sub-
- strings by name. It is also possible to extract the data directly, by
- first converting the name to a number in order to access the correct
- pointers in the output vector (described with pcre2_match() below). To
- do the conversion, you need to use the name-to-number map, which is
- described by these three values.
+ pcre2_substring_get_byname() are provided for extracting captured sub-
+ strings by name. It is also possible to extract the data directly, by
+ first converting the name to a number in order to access the correct
+ pointers in the output vector (described with pcre2_match() below). To
+ do the conversion, you need to use the name-to-number map, which is de-
+ scribed by these three values.
- The map consists of a number of fixed-size entries. PCRE2_INFO_NAME-
- COUNT gives the number of entries, and PCRE2_INFO_NAMEENTRYSIZE gives
- the size of each entry in code units; both of these return a uint32_t
+ The map consists of a number of fixed-size entries. PCRE2_INFO_NAME-
+ COUNT gives the number of entries, and PCRE2_INFO_NAMEENTRYSIZE gives
+ the size of each entry in code units; both of these return a uint32_t
value. The entry size depends on the length of the longest name.
PCRE2_INFO_NAMETABLE returns a pointer to the first entry of the table.
- This is a PCRE2_SPTR pointer to a block of code units. In the 8-bit
- library, the first two bytes of each entry are the number of the cap-
- turing parenthesis, most significant byte first. In the 16-bit library,
- the pointer points to 16-bit code units, the first of which contains
- the parenthesis number. In the 32-bit library, the pointer points to
- 32-bit code units, the first of which contains the parenthesis number.
+ This is a PCRE2_SPTR pointer to a block of code units. In the 8-bit li-
+ brary, the first two bytes of each entry are the number of the captur-
+ ing parenthesis, most significant byte first. In the 16-bit library,
+ the pointer points to 16-bit code units, the first of which contains
+ the parenthesis number. In the 32-bit library, the pointer points to
+ 32-bit code units, the first of which contains the parenthesis number.
The rest of the entry is the corresponding name, zero terminated.
- The names are in alphabetical order. If (?| is used to create multiple
- capture groups with the same number, as described in the section on
- duplicate group numbers in the pcre2pattern page, the groups may be
- given the same name, but there is only one entry in the table. Differ-
- ent names for groups of the same number are not permitted.
+ The names are in alphabetical order. If (?| is used to create multiple
+ capture groups with the same number, as described in the section on du-
+ plicate group numbers in the pcre2pattern page, the groups may be given
+ the same name, but there is only one entry in the table. Different
+ names for groups of the same number are not permitted.
- Duplicate names for capture groups with different numbers are permit-
+ Duplicate names for capture groups with different numbers are permit-
ted, but only if PCRE2_DUPNAMES is set. They appear in the table in the
- order in which they were found in the pattern. In the absence of (?|
- this is the order of increasing number; when (?| is used this is not
- necessarily the case because later capture groups may have lower num-
+ order in which they were found in the pattern. In the absence of (?|
+ this is the order of increasing number; when (?| is used this is not
+ necessarily the case because later capture groups may have lower num-
bers.
- As a simple example of the name/number table, consider the following
- pattern after compilation by the 8-bit library (assume PCRE2_EXTENDED
+ As a simple example of the name/number table, consider the following
+ pattern after compilation by the 8-bit library (assume PCRE2_EXTENDED
is set, so white space - including newlines - is ignored):
(?<date> (?<year>(\d\d)?\d\d) -
@@ -2296,7 +2289,7 @@
(?<month>\d\d) - (?<day>\d\d) )
There are four named capture groups, so the table has four entries, and
- each entry in the table is eight bytes long. The table is as follows,
+ each entry in the table is eight bytes long. The table is as follows,
with non-printing bytes shows in hexadecimal, and undefined bytes shown
as ??:
@@ -2305,8 +2298,8 @@
00 04 m o n t h 00
00 02 y e a r 00 ??
- When writing code to extract data from named capture groups using the
- name-to-number map, remember that the length of the entries is likely
+ When writing code to extract data from named capture groups using the
+ name-to-number map, remember that the length of the entries is likely
to be different for each compiled pattern.
PCRE2_INFO_NEWLINE
@@ -2325,15 +2318,15 @@
PCRE2_INFO_SIZE
- Return the size of the compiled pattern in bytes (for all three
- libraries). The third argument should point to a size_t variable. This
- value includes the size of the general data block that precedes the
- code units of the compiled pattern itself. The value that is used when
- pcre2_compile() is getting memory in which to place the compiled pat-
- tern may be slightly larger than the value returned by this option,
- because there are cases where the code that calculates the size has to
- over-estimate. Processing a pattern with the JIT compiler does not
- alter the value returned by this option.
+ Return the size of the compiled pattern in bytes (for all three li-
+ braries). The third argument should point to a size_t variable. This
+ value includes the size of the general data block that precedes the
+ code units of the compiled pattern itself. The value that is used when
+ pcre2_compile() is getting memory in which to place the compiled pat-
+ tern may be slightly larger than the value returned by this option, be-
+ cause there are cases where the code that calculates the size has to
+ over-estimate. Processing a pattern with the JIT compiler does not al-
+ ter the value returned by this option.
INFORMATION ABOUT A PATTERN'S CALLOUTS
@@ -2343,30 +2336,30 @@
void *user_data);
A script language that supports the use of string arguments in callouts
- might like to scan all the callouts in a pattern before running the
+ might like to scan all the callouts in a pattern before running the
match. This can be done by calling pcre2_callout_enumerate(). The first
- argument is a pointer to a compiled pattern, the second points to a
- callback function, and the third is arbitrary user data. The callback
- function is called for every callout in the pattern in the order in
+ argument is a pointer to a compiled pattern, the second points to a
+ callback function, and the third is arbitrary user data. The callback
+ function is called for every callout in the pattern in the order in
which they appear. Its first argument is a pointer to a callout enumer-
- ation block, and its second argument is the user_data value that was
- passed to pcre2_callout_enumerate(). The contents of the callout enu-
- meration block are described in the pcre2callout documentation, which
+ ation block, and its second argument is the user_data value that was
+ passed to pcre2_callout_enumerate(). The contents of the callout enu-
+ meration block are described in the pcre2callout documentation, which
also gives further details about callouts.
SERIALIZATION AND PRECOMPILING
- It is possible to save compiled patterns on disc or elsewhere, and
- reload them later, subject to a number of restrictions. The host on
- which the patterns are reloaded must be running the same version of
+ It is possible to save compiled patterns on disc or elsewhere, and
+ reload them later, subject to a number of restrictions. The host on
+ which the patterns are reloaded must be running the same version of
PCRE2, with the same code unit width, and must also have the same endi-
- anness, pointer width, and PCRE2_SIZE type. Before compiled patterns
- can be saved, they must be converted to a "serialized" form, which in
- the case of PCRE2 is really just a bytecode dump. The functions whose
- names begin with pcre2_serialize_ are used for converting to and from
- the serialized form. They are described in the pcre2serialize documen-
- tation. Note that PCRE2 serialization does not convert compiled pat-
+ anness, pointer width, and PCRE2_SIZE type. Before compiled patterns
+ can be saved, they must be converted to a "serialized" form, which in
+ the case of PCRE2 is really just a bytecode dump. The functions whose
+ names begin with pcre2_serialize_ are used for converting to and from
+ the serialized form. They are described in the pcre2serialize documen-
+ tation. Note that PCRE2 serialization does not convert compiled pat-
terns to an abstract format like Java or .NET serialization.
@@ -2380,60 +2373,58 @@
void pcre2_match_data_free(pcre2_match_data *match_data);
- Information about a successful or unsuccessful match is placed in a
- match data block, which is an opaque structure that is accessed by
- function calls. In particular, the match data block contains a vector
- of offsets into the subject string that define the matched part of the
- subject and any substrings that were captured. This is known as the
+ Information about a successful or unsuccessful match is placed in a
+ match data block, which is an opaque structure that is accessed by
+ function calls. In particular, the match data block contains a vector
+ of offsets into the subject string that define the matched part of the
+ subject and any substrings that were captured. This is known as the
ovector.
- Before calling pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match()
+ Before calling pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match()
you must create a match data block by calling one of the creation func-
- tions above. For pcre2_match_data_create(), the first argument is the
- number of pairs of offsets in the ovector. One pair of offsets is
- required to identify the string that matched the whole pattern, with an
- additional pair for each captured substring. For example, a value of 4
- creates enough space to record the matched portion of the subject plus
- three captured substrings. A minimum of at least 1 pair is imposed by
+ tions above. For pcre2_match_data_create(), the first argument is the
+ number of pairs of offsets in the ovector. One pair of offsets is re-
+ quired to identify the string that matched the whole pattern, with an
+ additional pair for each captured substring. For example, a value of 4
+ creates enough space to record the matched portion of the subject plus
+ three captured substrings. A minimum of at least 1 pair is imposed by
pcre2_match_data_create(), so it is always possible to return the over-
all matched string.
The second argument of pcre2_match_data_create() is a pointer to a gen-
- eral context, which can specify custom memory management for obtaining
+ eral context, which can specify custom memory management for obtaining
the memory for the match data block. If you are not using custom memory
management, pass NULL, which causes malloc() to be used.
- For pcre2_match_data_create_from_pattern(), the first argument is a
+ For pcre2_match_data_create_from_pattern(), the first argument is a
pointer to a compiled pattern. The ovector is created to be exactly the
right size to hold all the substrings a pattern might capture. The sec-
- ond argument is again a pointer to a general context, but in this case
+ ond argument is again a pointer to a general context, but in this case
if NULL is passed, the memory is obtained using the same allocator that
was used for the compiled pattern (custom or default).
- A match data block can be used many times, with the same or different
- compiled patterns. You can extract information from a match data block
- after a match operation has finished, using functions that are
- described in the sections on matched strings and other match data
- below.
+ A match data block can be used many times, with the same or different
+ compiled patterns. You can extract information from a match data block
+ after a match operation has finished, using functions that are de-
+ scribed in the sections on matched strings and other match data below.
When a call of pcre2_match() fails, valid data is available in the
- match block only when the error is PCRE2_ERROR_NOMATCH,
- PCRE2_ERROR_PARTIAL, or one of the error codes for an invalid UTF
- string. Exactly what is available depends on the error, and is detailed
- below.
+ match block only when the error is PCRE2_ERROR_NOMATCH, PCRE2_ER-
+ ROR_PARTIAL, or one of the error codes for an invalid UTF string. Ex-
+ actly what is available depends on the error, and is detailed below.
- When one of the matching functions is called, pointers to the compiled
- pattern and the subject string are set in the match data block so that
- they can be referenced by the extraction functions after a successful
+ When one of the matching functions is called, pointers to the compiled
+ pattern and the subject string are set in the match data block so that
+ they can be referenced by the extraction functions after a successful
match. After running a match, you must not free a compiled pattern or a
- subject string until after all operations on the match data block (for
- that match) have taken place, unless, in the case of the subject
- string, you have used the PCRE2_COPY_MATCHED_SUBJECT option, which is
- described in the section entitled "Option bits for pcre2_match()"
- below.
+ subject string until after all operations on the match data block (for
+ that match) have taken place, unless, in the case of the subject
+ string, you have used the PCRE2_COPY_MATCHED_SUBJECT option, which is
+ described in the section entitled "Option bits for pcre2_match()" be-
+ low.
- When a match data block itself is no longer needed, it should be freed
- by calling pcre2_match_data_free(). If this function is called with a
+ When a match data block itself is no longer needed, it should be freed
+ by calling pcre2_match_data_free(). If this function is called with a
NULL argument, it returns immediately, without doing anything.
@@ -2444,15 +2435,15 @@
uint32_t options, pcre2_match_data *match_data,
pcre2_match_context *mcontext);
- The function pcre2_match() is called to match a subject string against
- a compiled pattern, which is passed in the code argument. You can call
+ The function pcre2_match() is called to match a subject string against
+ a compiled pattern, which is passed in the code argument. You can call
pcre2_match() with the same code argument as many times as you like, in
- order to find multiple matches in the subject string or to match dif-
+ order to find multiple matches in the subject string or to match dif-
ferent subject strings with the same pattern.
- This function is the main matching facility of the library, and it
- operates in a Perl-like manner. For specialist use there is also an
- alternative matching function, which is described below in the section
+ This function is the main matching facility of the library, and it op-
+ erates in a Perl-like manner. For specialist use there is also an al-
+ ternative matching function, which is described below in the section
about the pcre2_dfa_match() function.
Here is an example of a simple call to pcre2_match():
@@ -2467,7 +2458,7 @@
md, /* the match data block */
NULL); /* a match context; NULL means use defaults */
- If the subject string is zero-terminated, the length can be given as
+ If the subject string is zero-terminated, the length can be given as
PCRE2_ZERO_TERMINATED. A match context must be provided if certain less
common matching parameters are to be changed. For details, see the sec-
tion on the match context above.
@@ -2474,110 +2465,110 @@
The string to be matched by pcre2_match()
- The subject string is passed to pcre2_match() as a pointer in subject,
- a length in length, and a starting offset in startoffset. The length
- and offset are in code units, not characters. That is, they are in
- bytes for the 8-bit library, 16-bit code units for the 16-bit library,
- and 32-bit code units for the 32-bit library, whether or not UTF pro-
+ The subject string is passed to pcre2_match() as a pointer in subject,
+ a length in length, and a starting offset in startoffset. The length
+ and offset are in code units, not characters. That is, they are in
+ bytes for the 8-bit library, 16-bit code units for the 16-bit library,
+ and 32-bit code units for the 32-bit library, whether or not UTF pro-
cessing is enabled.
If startoffset is greater than the length of the subject, pcre2_match()
- returns PCRE2_ERROR_BADOFFSET. When the starting offset is zero, the
- search for a match starts at the beginning of the subject, and this is
+ returns PCRE2_ERROR_BADOFFSET. When the starting offset is zero, the
+ search for a match starts at the beginning of the subject, and this is
by far the most common case. In UTF-8 or UTF-16 mode, the starting off-
- set must point to the start of a character, or to the end of the sub-
- ject (in UTF-32 mode, one code unit equals one character, so all off-
- sets are valid). Like the pattern string, the subject may contain
- binary zeros.
+ set must point to the start of a character, or to the end of the sub-
+ ject (in UTF-32 mode, one code unit equals one character, so all off-
+ sets are valid). Like the pattern string, the subject may contain bi-
+ nary zeros.
- A non-zero starting offset is useful when searching for another match
- in the same subject by calling pcre2_match() again after a previous
- success. Setting startoffset differs from passing over a shortened
- string and setting PCRE2_NOTBOL in the case of a pattern that begins
+ A non-zero starting offset is useful when searching for another match
+ in the same subject by calling pcre2_match() again after a previous
+ success. Setting startoffset differs from passing over a shortened
+ string and setting PCRE2_NOTBOL in the case of a pattern that begins
with any kind of lookbehind. For example, consider the pattern
\Biss\B
- which finds occurrences of "iss" in the middle of words. (\B matches
- only if the current position in the subject is not a word boundary.)
+ which finds occurrences of "iss" in the middle of words. (\B matches
+ only if the current position in the subject is not a word boundary.)
When applied to the string "Mississipi" the first call to pcre2_match()
- finds the first occurrence. If pcre2_match() is called again with just
- the remainder of the subject, namely "issipi", it does not match,
- because \B is always false at the start of the subject, which is deemed
- to be a word boundary. However, if pcre2_match() is passed the entire
+ finds the first occurrence. If pcre2_match() is called again with just
+ the remainder of the subject, namely "issipi", it does not match, be-
+ cause \B is always false at the start of the subject, which is deemed
+ to be a word boundary. However, if pcre2_match() is passed the entire
string again, but with startoffset set to 4, it finds the second occur-
- rence of "iss" because it is able to look behind the starting point to
+ rence of "iss" because it is able to look behind the starting point to
discover that it is preceded by a letter.
- Finding all the matches in a subject is tricky when the pattern can
+ Finding all the matches in a subject is tricky when the pattern can
match an empty string. It is possible to emulate Perl's /g behaviour by
- first trying the match again at the same offset, with the
- PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED options, and then if that
- fails, advancing the starting offset and trying an ordinary match
- again. There is some code that demonstrates how to do this in the
- pcre2demo sample program. In the most general case, you have to check
- to see if the newline convention recognizes CRLF as a newline, and if
- so, and the current character is CR followed by LF, advance the start-
+ first trying the match again at the same offset, with the
+ PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED options, and then if that
+ fails, advancing the starting offset and trying an ordinary match
+ again. There is some code that demonstrates how to do this in the
+ pcre2demo sample program. In the most general case, you have to check
+ to see if the newline convention recognizes CRLF as a newline, and if
+ so, and the current character is CR followed by LF, advance the start-
ing offset by two characters instead of one.
If a non-zero starting offset is passed when the pattern is anchored, a
single attempt to match at the given offset is made. This can only suc-
- ceed if the pattern does not require the match to be at the start of
- the subject. In other words, the anchoring must be the result of set-
- ting the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL, not
+ ceed if the pattern does not require the match to be at the start of
+ the subject. In other words, the anchoring must be the result of set-
+ ting the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL, not
by starting the pattern with ^ or \A.
Option bits for pcre2_match()
The unused bits of the options argument for pcre2_match() must be zero.
- The only bits that may be set are PCRE2_ANCHORED,
- PCRE2_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL,
- PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART, PCRE2_NO_JIT,
- PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PARTIAL_SOFT. Their
+ The only bits that may be set are PCRE2_ANCHORED,
+ PCRE2_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL, PCRE2_NO-
+ TEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART, PCRE2_NO_JIT,
+ PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PARTIAL_SOFT. Their
action is described below.
- Setting PCRE2_ANCHORED or PCRE2_ENDANCHORED at match time is not sup-
- ported by the just-in-time (JIT) compiler. If it is set, JIT matching
- is disabled and the interpretive code in pcre2_match() is run. Apart
- from PCRE2_NO_JIT (obviously), the remaining options are supported for
+ Setting PCRE2_ANCHORED or PCRE2_ENDANCHORED at match time is not sup-
+ ported by the just-in-time (JIT) compiler. If it is set, JIT matching
+ is disabled and the interpretive code in pcre2_match() is run. Apart
+ from PCRE2_NO_JIT (obviously), the remaining options are supported for
JIT matching.
PCRE2_ANCHORED
The PCRE2_ANCHORED option limits pcre2_match() to matching at the first
- matching position. If a pattern was compiled with PCRE2_ANCHORED, or
- turned out to be anchored by virtue of its contents, it cannot be made
- unachored at matching time. Note that setting the option at match time
+ matching position. If a pattern was compiled with PCRE2_ANCHORED, or
+ turned out to be anchored by virtue of its contents, it cannot be made
+ unachored at matching time. Note that setting the option at match time
disables JIT matching.
PCRE2_COPY_MATCHED_SUBJECT
- By default, a pointer to the subject is remembered in the match data
- block so that, after a successful match, it can be referenced by the
- substring extraction functions. This means that the subject's memory
- must not be freed until all such operations are complete. For some
- applications where the lifetime of the subject string is not guaran-
- teed, it may be necessary to make a copy of the subject string, but it
- is wasteful to do this unless the match is successful. After a success-
- ful match, if PCRE2_COPY_MATCHED_SUBJECT is set, the subject is copied
- and the new pointer is remembered in the match data block instead of
- the original subject pointer. The memory allocator that was used for
- the match block itself is used. The copy is automatically freed when
- pcre2_match_data_free() is called to free the match data block. It is
+ By default, a pointer to the subject is remembered in the match data
+ block so that, after a successful match, it can be referenced by the
+ substring extraction functions. This means that the subject's memory
+ must not be freed until all such operations are complete. For some ap-
+ plications where the lifetime of the subject string is not guaranteed,
+ it may be necessary to make a copy of the subject string, but it is
+ wasteful to do this unless the match is successful. After a successful
+ match, if PCRE2_COPY_MATCHED_SUBJECT is set, the subject is copied and
+ the new pointer is remembered in the match data block instead of the
+ original subject pointer. The memory allocator that was used for the
+ match block itself is used. The copy is automatically freed when
+ pcre2_match_data_free() is called to free the match data block. It is
also automatically freed if the match data block is re-used for another
match operation.
PCRE2_ENDANCHORED
- If the PCRE2_ENDANCHORED option is set, any string that pcre2_match()
- matches must be right at the end of the subject string. Note that set-
+ If the PCRE2_ENDANCHORED option is set, any string that pcre2_match()
+ matches must be right at the end of the subject string. Note that set-
ting the option at match time disables JIT matching.
PCRE2_NOTBOL
This option specifies that first character of the subject string is not
- the beginning of a line, so the circumflex metacharacter should not
- match before it. Setting this without having set PCRE2_MULTILINE at
+ the beginning of a line, so the circumflex metacharacter should not
+ match before it. Setting this without having set PCRE2_MULTILINE at
compile time causes circumflex never to match. This option affects only
the behaviour of the circumflex metacharacter. It does not affect \A.
@@ -2584,9 +2575,9 @@
PCRE2_NOTEOL
This option specifies that the end of the subject string is not the end
- of a line, so the dollar metacharacter should not match it nor (except
- in multiline mode) a newline immediately before it. Setting this with-
- out having set PCRE2_MULTILINE at compile time causes dollar never to
+ of a line, so the dollar metacharacter should not match it nor (except
+ in multiline mode) a newline immediately before it. Setting this with-
+ out having set PCRE2_MULTILINE at compile time causes dollar never to
match. This option affects only the behaviour of the dollar metacharac-
ter. It does not affect \Z or \z.
@@ -2593,85 +2584,85 @@
PCRE2_NOTEMPTY
An empty string is not considered to be a valid match if this option is
- set. If there are alternatives in the pattern, they are tried. If all
- the alternatives match the empty string, the entire match fails. For
+ set. If there are alternatives in the pattern, they are tried. If all
+ the alternatives match the empty string, the entire match fails. For
example, if the pattern
a?b?
- is applied to a string not beginning with "a" or "b", it matches an
+ is applied to a string not beginning with "a" or "b", it matches an
empty string at the start of the subject. With PCRE2_NOTEMPTY set, this
- match is not valid, so pcre2_match() searches further into the string
+ match is not valid, so pcre2_match() searches further into the string
for occurrences of "a" or "b".
PCRE2_NOTEMPTY_ATSTART
- This is like PCRE2_NOTEMPTY, except that it locks out an empty string
+ This is like PCRE2_NOTEMPTY, except that it locks out an empty string
match only at the first matching position, that is, at the start of the
- subject plus the starting offset. An empty string match later in the
- subject is permitted. If the pattern is anchored, such a match can
- occur only if the pattern contains \K.
+ subject plus the starting offset. An empty string match later in the
+ subject is permitted. If the pattern is anchored, such a match can oc-
+ cur only if the pattern contains \K.
PCRE2_NO_JIT
- By default, if a pattern has been successfully processed by
- pcre2_jit_compile(), JIT is automatically used when pcre2_match() is
- called with options that JIT supports. Setting PCRE2_NO_JIT disables
+ By default, if a pattern has been successfully processed by
+ pcre2_jit_compile(), JIT is automatically used when pcre2_match() is
+ called with options that JIT supports. Setting PCRE2_NO_JIT disables
the use of JIT; it forces matching to be done by the interpreter.
PCRE2_NO_UTF_CHECK
When PCRE2_UTF is set at compile time, the validity of the subject as a
- UTF string is checked unless PCRE2_NO_UTF_CHECK is passed to
+ UTF string is checked unless PCRE2_NO_UTF_CHECK is passed to
pcre2_match() or PCRE2_MATCH_INVALID_UTF was passed to pcre2_compile().
The latter special case is discussed in detail in the pcre2unicode doc-
umentation.
- In the default case, if a non-zero starting offset is given, the check
- is applied only to that part of the subject that could be inspected
- during matching, and there is a check that the starting offset points
- to the first code unit of a character or to the end of the subject. If
- there are no lookbehind assertions in the pattern, the check starts at
+ In the default case, if a non-zero starting offset is given, the check
+ is applied only to that part of the subject that could be inspected
+ during matching, and there is a check that the starting offset points
+ to the first code unit of a character or to the end of the subject. If
+ there are no lookbehind assertions in the pattern, the check starts at
the starting offset. Otherwise, it starts at the length of the longest
- lookbehind before the starting offset, or at the start of the subject
- if there are not that many characters before the starting offset. Note
+ lookbehind before the starting offset, or at the start of the subject
+ if there are not that many characters before the starting offset. Note
that the sequences \b and \B are one-character lookbehinds.
The check is carried out before any other processing takes place, and a
- negative error code is returned if the check fails. There are several
- UTF error codes for each code unit width, corresponding to different
- problems with the code unit sequence. There are discussions about the
- validity of UTF-8 strings, UTF-16 strings, and UTF-32 strings in the
+ negative error code is returned if the check fails. There are several
+ UTF error codes for each code unit width, corresponding to different
+ problems with the code unit sequence. There are discussions about the
+ validity of UTF-8 strings, UTF-16 strings, and UTF-32 strings in the
pcre2unicode documentation.
If you know that your subject is valid, and you want to skip this check
for performance reasons, you can set the PCRE2_NO_UTF_CHECK option when
- calling pcre2_match(). You might want to do this for the second and
- subsequent calls to pcre2_match() if you are making repeated calls to
+ calling pcre2_match(). You might want to do this for the second and
+ subsequent calls to pcre2_match() if you are making repeated calls to
find multiple matches in the same subject string.
- Warning: Unless PCRE2_MATCH_INVALID_UTF was set at compile time, when
- PCRE2_NO_UTF_CHECK is set at match time the effect of passing an
- invalid string as a subject, or an invalid value of startoffset, is
- undefined. Your program may crash or loop indefinitely or give wrong
- results.
+ Warning: Unless PCRE2_MATCH_INVALID_UTF was set at compile time, when
+ PCRE2_NO_UTF_CHECK is set at match time the effect of passing an in-
+ valid string as a subject, or an invalid value of startoffset, is unde-
+ fined. Your program may crash or loop indefinitely or give wrong re-
+ sults.
PCRE2_PARTIAL_HARD
PCRE2_PARTIAL_SOFT
- These options turn on the partial matching feature. A partial match
- occurs if the end of the subject string is reached successfully, but
- there are not enough subject characters to complete the match. If this
- happens when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD) is set,
- matching continues by testing any remaining alternatives. Only if no
- complete match can be found is PCRE2_ERROR_PARTIAL returned instead of
- PCRE2_ERROR_NOMATCH. In other words, PCRE2_PARTIAL_SOFT specifies that
- the caller is prepared to handle a partial match, but only if no com-
+ These options turn on the partial matching feature. A partial match oc-
+ curs if the end of the subject string is reached successfully, but
+ there are not enough subject characters to complete the match. If this
+ happens when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD) is set,
+ matching continues by testing any remaining alternatives. Only if no
+ complete match can be found is PCRE2_ERROR_PARTIAL returned instead of
+ PCRE2_ERROR_NOMATCH. In other words, PCRE2_PARTIAL_SOFT specifies that
+ the caller is prepared to handle a partial match, but only if no com-
plete match can be found.
- If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
- case, if a partial match is found, pcre2_match() immediately returns
- PCRE2_ERROR_PARTIAL, without considering any other alternatives. In
+ If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
+ case, if a partial match is found, pcre2_match() immediately returns
+ PCRE2_ERROR_PARTIAL, without considering any other alternatives. In
other words, when PCRE2_PARTIAL_HARD is set, a partial match is consid-
ered to be more important that an alternative complete match.
@@ -2681,38 +2672,38 @@
NEWLINE HANDLING WHEN MATCHING
- When PCRE2 is built, a default newline convention is set; this is usu-
- ally the standard convention for the operating system. The default can
- be overridden in a compile context by calling pcre2_set_newline(). It
- can also be overridden by starting a pattern string with, for example,
- (*CRLF), as described in the section on newline conventions in the
- pcre2pattern page. During matching, the newline choice affects the be-
- haviour of the dot, circumflex, and dollar metacharacters. It may also
- alter the way the match starting position is advanced after a match
+ When PCRE2 is built, a default newline convention is set; this is usu-
+ ally the standard convention for the operating system. The default can
+ be overridden in a compile context by calling pcre2_set_newline(). It
+ can also be overridden by starting a pattern string with, for example,
+ (*CRLF), as described in the section on newline conventions in the
+ pcre2pattern page. During matching, the newline choice affects the be-
+ haviour of the dot, circumflex, and dollar metacharacters. It may also
+ alter the way the match starting position is advanced after a match
failure for an unanchored pattern.
When PCRE2_NEWLINE_CRLF, PCRE2_NEWLINE_ANYCRLF, or PCRE2_NEWLINE_ANY is
- set as the newline convention, and a match attempt for an unanchored
+ set as the newline convention, and a match attempt for an unanchored
pattern fails when the current starting position is at a CRLF sequence,
- and the pattern contains no explicit matches for CR or LF characters,
- the match position is advanced by two characters instead of one, in
+ and the pattern contains no explicit matches for CR or LF characters,
+ the match position is advanced by two characters instead of one, in
other words, to after the CRLF.
The above rule is a compromise that makes the most common cases work as
- expected. For example, if the pattern is .+A (and the PCRE2_DOTALL
- option is not set), it does not match the string "\r\nA" because, after
- failing at the start, it skips both the CR and the LF before retrying.
- However, the pattern [\r\n]A does match that string, because it con-
+ expected. For example, if the pattern is .+A (and the PCRE2_DOTALL op-
+ tion is not set), it does not match the string "\r\nA" because, after
+ failing at the start, it skips both the CR and the LF before retrying.
+ However, the pattern [\r\n]A does match that string, because it con-
tains an explicit CR or LF reference, and so advances only by one char-
acter after the first failure.
An explicit match for CR of LF is either a literal appearance of one of
- those characters in the pattern, or one of the \r or \n or equivalent
+ those characters in the pattern, or one of the \r or \n or equivalent
octal or hexadecimal escape sequences. Implicit matches such as [^X] do
- not count, nor does \s, even though it includes CR and LF in the char-
+ not count, nor does \s, even though it includes CR and LF in the char-
acters that it matches.
- Notwithstanding the above, anomalous effects may still occur when CRLF
+ Notwithstanding the above, anomalous effects may still occur when CRLF
is a valid newline sequence and explicit \r or \n escapes appear in the
pattern.
@@ -2723,82 +2714,82 @@
PCRE2_SIZE *pcre2_get_ovector_pointer(pcre2_match_data *match_data);
- In general, a pattern matches a certain portion of the subject, and in
- addition, further substrings from the subject may be picked out by
- parenthesized parts of the pattern. Following the usage in Jeffrey
- Friedl's book, this is called "capturing" in what follows, and the
- phrase "capture group" (Perl terminology) is used for a fragment of a
- pattern that picks out a substring. PCRE2 supports several other kinds
+ In general, a pattern matches a certain portion of the subject, and in
+ addition, further substrings from the subject may be picked out by
+ parenthesized parts of the pattern. Following the usage in Jeffrey
+ Friedl's book, this is called "capturing" in what follows, and the
+ phrase "capture group" (Perl terminology) is used for a fragment of a
+ pattern that picks out a substring. PCRE2 supports several other kinds
of parenthesized group that do not cause substrings to be captured. The
- pcre2_pattern_info() function can be used to find out how many capture
+ pcre2_pattern_info() function can be used to find out how many capture
groups there are in a compiled pattern.
- You can use auxiliary functions for accessing captured substrings by
+ You can use auxiliary functions for accessing captured substrings by
number or by name, as described in sections below.
Alternatively, you can make direct use of the vector of PCRE2_SIZE val-
- ues, called the ovector, which contains the offsets of captured
- strings. It is part of the match data block. The function
- pcre2_get_ovector_pointer() returns the address of the ovector, and
+ ues, called the ovector, which contains the offsets of captured
+ strings. It is part of the match data block. The function
+ pcre2_get_ovector_pointer() returns the address of the ovector, and
pcre2_get_ovector_count() returns the number of pairs of values it con-
tains.
Within the ovector, the first in each pair of values is set to the off-
set of the first code unit of a substring, and the second is set to the
- offset of the first code unit after the end of a substring. These val-
- ues are always code unit offsets, not character offsets. That is, they
- are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit
- library, and 32-bit offsets in the 32-bit library.
+ offset of the first code unit after the end of a substring. These val-
+ ues are always code unit offsets, not character offsets. That is, they
+ are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit li-
+ brary, and 32-bit offsets in the 32-bit library.
- After a partial match (error return PCRE2_ERROR_PARTIAL), only the
- first pair of offsets (that is, ovector[0] and ovector[1]) are set.
- They identify the part of the subject that was partially matched. See
+ After a partial match (error return PCRE2_ERROR_PARTIAL), only the
+ first pair of offsets (that is, ovector[0] and ovector[1]) are set.
+ They identify the part of the subject that was partially matched. See
the pcre2partial documentation for details of partial matching.
- After a fully successful match, the first pair of offsets identifies
- the portion of the subject string that was matched by the entire pat-
- tern. The next pair is used for the first captured substring, and so
- on. The value returned by pcre2_match() is one more than the highest
- numbered pair that has been set. For example, if two substrings have
- been captured, the returned value is 3. If there are no captured sub-
+ After a fully successful match, the first pair of offsets identifies
+ the portion of the subject string that was matched by the entire pat-
+ tern. The next pair is used for the first captured substring, and so
+ on. The value returned by pcre2_match() is one more than the highest
+ numbered pair that has been set. For example, if two substrings have
+ been captured, the returned value is 3. If there are no captured sub-
strings, the return value from a successful match is 1, indicating that
just the first pair of offsets has been set.
- If a pattern uses the \K escape sequence within a positive assertion,
+ If a pattern uses the \K escape sequence within a positive assertion,
the reported start of a successful match can be greater than the end of
- the match. For example, if the pattern (?=ab\K) is matched against
+ the match. For example, if the pattern (?=ab\K) is matched against
"ab", the start and end offset values for the match are 2 and 0.
- If a capture group is matched repeatedly within a single match opera-
- tion, it is the last portion of the subject that it matched that is
- returned.
+ If a capture group is matched repeatedly within a single match opera-
+ tion, it is the last portion of the subject that it matched that is re-
+ turned.
If the ovector is too small to hold all the captured substring offsets,
- as much as possible is filled in, and the function returns a value of
- zero. If captured substrings are not of interest, pcre2_match() may be
+ as much as possible is filled in, and the function returns a value of
+ zero. If captured substrings are not of interest, pcre2_match() may be
called with a match data block whose ovector is of minimum length (that
is, one pair).
- It is possible for capture group number n+1 to match some part of the
- subject when group n has not been used at all. For example, if the
+ It is possible for capture group number n+1 to match some part of the
+ subject when group n has not been used at all. For example, if the
string "abc" is matched against the pattern (a|(z))(bc) the return from
- the function is 4, and groups 1 and 3 are matched, but 2 is not. When
- this happens, both values in the offset pairs corresponding to unused
+ the function is 4, and groups 1 and 3 are matched, but 2 is not. When
+ this happens, both values in the offset pairs corresponding to unused
groups are set to PCRE2_UNSET.
- Offset values that correspond to unused groups at the end of the
- expression are also set to PCRE2_UNSET. For example, if the string
- "abc" is matched against the pattern (abc)(x(yz)?)? groups 2 and 3 are
- not matched. The return from the function is 2, because the highest
- used capture group number is 1. The offsets for for the second and
- third capture groupss (assuming the vector is large enough, of course)
- are set to PCRE2_UNSET.
+ Offset values that correspond to unused groups at the end of the ex-
+ pression are also set to PCRE2_UNSET. For example, if the string "abc"
+ is matched against the pattern (abc)(x(yz)?)? groups 2 and 3 are not
+ matched. The return from the function is 2, because the highest used
+ capture group number is 1. The offsets for for the second and third
+ capture groupss (assuming the vector is large enough, of course) are
+ set to PCRE2_UNSET.
Elements in the ovector that do not correspond to capturing parentheses
in the pattern are never changed. That is, if a pattern contains n cap-
turing parentheses, no more than ovector[0] to ovector[2n+1] are set by
- pcre2_match(). The other elements retain whatever values they previ-
- ously had. After a failed match attempt, the contents of the ovector
+ pcre2_match(). The other elements retain whatever values they previ-
+ ously had. After a failed match attempt, the contents of the ovector
are unchanged.
@@ -2808,55 +2799,55 @@
PCRE2_SIZE pcre2_get_startchar(pcre2_match_data *match_data);
- As well as the offsets in the ovector, other information about a match
- is retained in the match data block and can be retrieved by the above
- functions in appropriate circumstances. If they are called at other
+ As well as the offsets in the ovector, other information about a match
+ is retained in the match data block and can be retrieved by the above
+ functions in appropriate circumstances. If they are called at other
times, the result is undefined.
- After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
- failure to match (PCRE2_ERROR_NOMATCH), a mark name may be available.
- The function pcre2_get_mark() can be called to access this name, which
- can be specified in the pattern by any of the backtracking control
+ After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
+ failure to match (PCRE2_ERROR_NOMATCH), a mark name may be available.
+ The function pcre2_get_mark() can be called to access this name, which
+ can be specified in the pattern by any of the backtracking control
verbs, not just (*MARK). The same function applies to all the verbs. It
returns a pointer to the zero-terminated name, which is within the com-
piled pattern. If no name is available, NULL is returned. The length of
- the name (excluding the terminating zero) is stored in the code unit
- that precedes the name. You should use this length instead of relying
+ the name (excluding the terminating zero) is stored in the code unit
+ that precedes the name. You should use this length instead of relying
on the terminating zero if the name might contain a binary zero.
- After a successful match, the name that is returned is the last mark
+ After a successful match, the name that is returned is the last mark
name encountered on the matching path through the pattern. Instances of
- backtracking verbs without names do not count. Thus, for example, if
+ backtracking verbs without names do not count. Thus, for example, if
the matching path contains (*MARK:A)(*PRUNE), the name "A" is returned.
- After a "no match" or a partial match, the last encountered name is
- returned. For example, consider this pattern:
+ After a "no match" or a partial match, the last encountered name is re-
+ turned. For example, consider this pattern:
^(*MARK:A)((*MARK:B)a|b)c
- When it matches "bc", the returned name is A. The B mark is "seen" in
- the first branch of the group, but it is not on the matching path. On
- the other hand, when this pattern fails to match "bx", the returned
+ When it matches "bc", the returned name is A. The B mark is "seen" in
+ the first branch of the group, but it is not on the matching path. On
+ the other hand, when this pattern fails to match "bx", the returned
name is B.
- Warning: By default, certain start-of-match optimizations are used to
- give a fast "no match" result in some situations. For example, if the
- anchoring is removed from the pattern above, there is an initial check
- for the presence of "c" in the subject before running the matching
- engine. This check fails for "bx", causing a match failure without see-
- ing any marks. You can disable the start-of-match optimizations by set-
- ting the PCRE2_NO_START_OPTIMIZE option for pcre2_compile() or by
- starting the pattern with (*NO_START_OPT).
+ Warning: By default, certain start-of-match optimizations are used to
+ give a fast "no match" result in some situations. For example, if the
+ anchoring is removed from the pattern above, there is an initial check
+ for the presence of "c" in the subject before running the matching en-
+ gine. This check fails for "bx", causing a match failure without seeing
+ any marks. You can disable the start-of-match optimizations by setting
+ the PCRE2_NO_START_OPTIMIZE option for pcre2_compile() or by starting
+ the pattern with (*NO_START_OPT).
- After a successful match, a partial match, or one of the invalid UTF
- errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
+ After a successful match, a partial match, or one of the invalid UTF
+ errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
be called. After a successful or partial match it returns the code unit
- offset of the character at which the match started. For a non-partial
- match, this can be different to the value of ovector[0] if the pattern
- contains the \K escape sequence. After a partial match, however, this
- value is always the same as ovector[0] because \K does not affect the
+ offset of the character at which the match started. For a non-partial
+ match, this can be different to the value of ovector[0] if the pattern
+ contains the \K escape sequence. After a partial match, however, this
+ value is always the same as ovector[0] because \K does not affect the
result of a partial match.
- After a UTF check failure, pcre2_get_startchar() can be used to obtain
+ After a UTF check failure, pcre2_get_startchar() can be used to obtain
the code unit offset of the invalid UTF character. Details are given in
the pcre2unicode page.
@@ -2863,14 +2854,14 @@
ERROR RETURNS FROM pcre2_match()
- If pcre2_match() fails, it returns a negative number. This can be con-
- verted to a text string by calling the pcre2_get_error_message() func-
- tion (see "Obtaining a textual error message" below). Negative error
- codes are also returned by other functions, and are documented with
- them. The codes are given names in the header file. If UTF checking is
+ If pcre2_match() fails, it returns a negative number. This can be con-
+ verted to a text string by calling the pcre2_get_error_message() func-
+ tion (see "Obtaining a textual error message" below). Negative error
+ codes are also returned by other functions, and are documented with
+ them. The codes are given names in the header file. If UTF checking is
in force and an invalid UTF subject string is detected, one of a number
- of UTF-specific negative error codes is returned. Details are given in
- the pcre2unicode page. The following are the other errors that may be
+ of UTF-specific negative error codes is returned. Details are given in
+ the pcre2unicode page. The following are the other errors that may be
returned by pcre2_match():
PCRE2_ERROR_NOMATCH
@@ -2879,20 +2870,20 @@
PCRE2_ERROR_PARTIAL
- The subject string did not match, but it did match partially. See the
+ The subject string did not match, but it did match partially. See the
pcre2partial documentation for details of partial matching.
PCRE2_ERROR_BADMAGIC
PCRE2 stores a 4-byte "magic number" at the start of the compiled code,
- to catch the case when it is passed a junk pointer. This is the error
+ to catch the case when it is passed a junk pointer. This is the error
that is returned when the magic number is not present.
PCRE2_ERROR_BADMODE
- This error is given when a compiled pattern is passed to a function in
- a library of a different code unit width, for example, a pattern com-
- piled by the 8-bit library is passed to a 16-bit or 32-bit library
+ This error is given when a compiled pattern is passed to a function in
+ a library of a different code unit width, for example, a pattern com-
+ piled by the 8-bit library is passed to a 16-bit or 32-bit library
function.
PCRE2_ERROR_BADOFFSET
@@ -2906,15 +2897,15 @@
PCRE2_ERROR_BADUTFOFFSET
The UTF code unit sequence that was passed as a subject was checked and
- found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
- value of startoffset did not point to the beginning of a UTF character
+ found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
+ value of startoffset did not point to the beginning of a UTF character
or the end of the subject.
PCRE2_ERROR_CALLOUT
- This error is never generated by pcre2_match() itself. It is provided
- for use by callout functions that want to cause pcre2_match() or
- pcre2_callout_enumerate() to return a distinctive error code. See the
+ This error is never generated by pcre2_match() itself. It is provided
+ for use by callout functions that want to cause pcre2_match() or
+ pcre2_callout_enumerate() to return a distinctive error code. See the
pcre2callout documentation for details.
PCRE2_ERROR_DEPTHLIMIT
@@ -2927,15 +2918,15 @@
PCRE2_ERROR_INTERNAL
- An unexpected internal error has occurred. This error could be caused
+ An unexpected internal error has occurred. This error could be caused
by a bug in PCRE2 or by overwriting of the compiled pattern.
PCRE2_ERROR_JIT_STACKLIMIT
- This error is returned when a pattern that was successfully studied
- using JIT is being matched, but the memory available for the just-in-
- time processing stack is not large enough. See the pcre2jit documenta-
- tion for more details.
+ This error is returned when a pattern that was successfully studied us-
+ ing JIT is being matched, but the memory available for the just-in-time
+ processing stack is not large enough. See the pcre2jit documentation
+ for more details.
PCRE2_ERROR_MATCHLIMIT
@@ -2943,11 +2934,11 @@
PCRE2_ERROR_NOMEMORY
- If a pattern contains many nested backtracking points, heap memory is
- used to remember them. This error is given when the memory allocation
- function (default or custom) fails. Note that a different error,
- PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds
- the heap limit. PCRE2_ERROR_NOMEMORY is also returned if
+ If a pattern contains many nested backtracking points, heap memory is
+ used to remember them. This error is given when the memory allocation
+ function (default or custom) fails. Note that a different error,
+ PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds
+ the heap limit. PCRE2_ERROR_NOMEMORY is also returned if
PCRE2_COPY_MATCHED_SUBJECT is set and memory allocation fails.
PCRE2_ERROR_NULL
@@ -2956,12 +2947,12 @@
PCRE2_ERROR_RECURSELOOP
- This error is returned when pcre2_match() detects a recursion loop
- within the pattern. Specifically, it means that either the whole pat-
+ This error is returned when pcre2_match() detects a recursion loop
+ within the pattern. Specifically, it means that either the whole pat-
tern or a capture group has been called recursively for the second time
- at the same position in the subject string. Some simple patterns that
- might do this are detected and faulted at compile time, but more com-
- plicated cases, in particular mutual recursions between two different
+ at the same position in the subject string. Some simple patterns that
+ might do this are detected and faulted at compile time, but more com-
+ plicated cases, in particular mutual recursions between two different
groups, cannot be detected until matching is attempted.
@@ -2970,21 +2961,21 @@
int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer,
PCRE2_SIZE bufflen);
- A text message for an error code from any PCRE2 function (compile,
- match, or auxiliary) can be obtained by calling pcre2_get_error_mes-
- sage(). The code is passed as the first argument, with the remaining
- two arguments specifying a code unit buffer and its length in code
- units, into which the text message is placed. The message is returned
- in code units of the appropriate width for the library that is being
+ A text message for an error code from any PCRE2 function (compile,
+ match, or auxiliary) can be obtained by calling pcre2_get_error_mes-
+ sage(). The code is passed as the first argument, with the remaining
+ two arguments specifying a code unit buffer and its length in code
+ units, into which the text message is placed. The message is returned
+ in code units of the appropriate width for the library that is being
used.
- The returned message is terminated with a trailing zero, and the func-
- tion returns the number of code units used, excluding the trailing
- zero. If the error number is unknown, the negative error code
- PCRE2_ERROR_BADDATA is returned. If the buffer is too small, the mes-
- sage is truncated (but still with a trailing zero), and the negative
- error code PCRE2_ERROR_NOMEMORY is returned. None of the messages are
- very long; a buffer size of 120 code units is ample.
+ The returned message is terminated with a trailing zero, and the func-
+ tion returns the number of code units used, excluding the trailing
+ zero. If the error number is unknown, the negative error code PCRE2_ER-
+ ROR_BADDATA is returned. If the buffer is too small, the message is
+ truncated (but still with a trailing zero), and the negative error code
+ PCRE2_ERROR_NOMEMORY is returned. None of the messages are very long;
+ a buffer size of 120 code units is ample.
EXTRACTING CAPTURED SUBSTRINGS BY NUMBER
@@ -3002,39 +2993,39 @@
void pcre2_substring_free(PCRE2_UCHAR *buffer);
- Captured substrings can be accessed directly by using the ovector as
+ Captured substrings can be accessed directly by using the ovector as
described above. For convenience, auxiliary functions are provided for
- extracting captured substrings as new, separate, zero-terminated
+ extracting captured substrings as new, separate, zero-terminated
strings. A substring that contains a binary zero is correctly extracted
- and has a further zero added on the end, but the result is not, of
+ and has a further zero added on the end, but the result is not, of
course, a C string.
The functions in this section identify substrings by number. The number
zero refers to the entire matched substring, with higher numbers refer-
- ring to substrings captured by parenthesized groups. After a partial
- match, only substring zero is available. An attempt to extract any
- other substring gives the error PCRE2_ERROR_PARTIAL. The next section
+ ring to substrings captured by parenthesized groups. After a partial
+ match, only substring zero is available. An attempt to extract any
+ other substring gives the error PCRE2_ERROR_PARTIAL. The next section
describes similar functions for extracting captured substrings by name.
- If a pattern uses the \K escape sequence within a positive assertion,
+ If a pattern uses the \K escape sequence within a positive assertion,
the reported start of a successful match can be greater than the end of
- the match. For example, if the pattern (?=ab\K) is matched against
- "ab", the start and end offset values for the match are 2 and 0. In
- this situation, calling these functions with a zero substring number
+ the match. For example, if the pattern (?=ab\K) is matched against
+ "ab", the start and end offset values for the match are 2 and 0. In
+ this situation, calling these functions with a zero substring number
extracts a zero-length empty string.
- You can find the length in code units of a captured substring without
- extracting it by calling pcre2_substring_length_bynumber(). The first
- argument is a pointer to the match data block, the second is the group
- number, and the third is a pointer to a variable into which the length
- is placed. If you just want to know whether or not the substring has
+ You can find the length in code units of a captured substring without
+ extracting it by calling pcre2_substring_length_bynumber(). The first
+ argument is a pointer to the match data block, the second is the group
+ number, and the third is a pointer to a variable into which the length
+ is placed. If you just want to know whether or not the substring has
been captured, you can pass the third argument as NULL.
- The pcre2_substring_copy_bynumber() function copies a captured sub-
- string into a supplied buffer, whereas pcre2_substring_get_bynumber()
- copies it into new memory, obtained using the same memory allocation
- function that was used for the match data block. The first two argu-
- ments of these functions are a pointer to the match data block and a
+ The pcre2_substring_copy_bynumber() function copies a captured sub-
+ string into a supplied buffer, whereas pcre2_substring_get_bynumber()
+ copies it into new memory, obtained using the same memory allocation
+ function that was used for the match data block. The first two argu-
+ ments of these functions are a pointer to the match data block and a
capture group number.
The final arguments of pcre2_substring_copy_bynumber() are a pointer to
@@ -3043,25 +3034,25 @@
for the extracted substring, excluding the terminating zero.
For pcre2_substring_get_bynumber() the third and fourth arguments point
- to variables that are updated with a pointer to the new memory and the
- number of code units that comprise the substring, again excluding the
- terminating zero. When the substring is no longer needed, the memory
+ to variables that are updated with a pointer to the new memory and the
+ number of code units that comprise the substring, again excluding the
+ terminating zero. When the substring is no longer needed, the memory
should be freed by calling pcre2_substring_free().
- The return value from all these functions is zero for success, or a
- negative error code. If the pattern match failed, the match failure
- code is returned. If a substring number greater than zero is used
- after a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
+ The return value from all these functions is zero for success, or a
+ negative error code. If the pattern match failed, the match failure
+ code is returned. If a substring number greater than zero is used af-
+ ter a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
error codes are:
PCRE2_ERROR_NOMEMORY
- The buffer was too small for pcre2_substring_copy_bynumber(), or the
+ The buffer was too small for pcre2_substring_copy_bynumber(), or the
attempt to get memory failed for pcre2_substring_get_bynumber().
PCRE2_ERROR_NOSUBSTRING
- There is no substring with that number in the pattern, that is, the
+ There is no substring with that number in the pattern, that is, the
number is greater than the number of capturing parentheses.
PCRE2_ERROR_UNAVAILABLE
@@ -3072,8 +3063,8 @@
PCRE2_ERROR_UNSET
- The substring did not participate in the match. For example, if the
- pattern is (abc)|(def) and the subject is "def", and the ovector con-
+ The substring did not participate in the match. For example, if the
+ pattern is (abc)|(def) and the subject is "def", and the ovector con-
tains at least two capturing slots, substring number 1 is unset.
@@ -3084,31 +3075,31 @@
void pcre2_substring_list_free(PCRE2_SPTR *list);
- The pcre2_substring_list_get() function extracts all available sub-
- strings and builds a list of pointers to them. It also (optionally)
- builds a second list that contains their lengths (in code units),
- excluding a terminating zero that is added to each of them. All this is
+ The pcre2_substring_list_get() function extracts all available sub-
+ strings and builds a list of pointers to them. It also (optionally)
+ builds a second list that contains their lengths (in code units), ex-
+ cluding a terminating zero that is added to each of them. All this is
done in a single block of memory that is obtained using the same memory
allocation function that was used to get the match data block.
- This function must be called only after a successful match. If called
+ This function must be called only after a successful match. If called
after a partial match, the error code PCRE2_ERROR_PARTIAL is returned.
- The address of the memory block is returned via listptr, which is also
+ The address of the memory block is returned via listptr, which is also
the start of the list of string pointers. The end of the list is marked
- by a NULL pointer. The address of the list of lengths is returned via
- lengthsptr. If your strings do not contain binary zeros and you do not
+ by a NULL pointer. The address of the list of lengths is returned via
+ lengthsptr. If your strings do not contain binary zeros and you do not
therefore need the lengths, you may supply NULL as the lengthsptr argu-
- ment to disable the creation of a list of lengths. The yield of the
- function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
- ory block could not be obtained. When the list is no longer needed, it
+ ment to disable the creation of a list of lengths. The yield of the
+ function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
+ ory block could not be obtained. When the list is no longer needed, it
should be freed by calling pcre2_substring_list_free().
If this function encounters a substring that is unset, which can happen
- when capture group number n+1 matches some part of the subject, but
- group n has not been used at all, it returns an empty string. This can
+ when capture group number n+1 matches some part of the subject, but
+ group n has not been used at all, it returns an empty string. This can
be distinguished from a genuine zero-length substring by inspecting the
- appropriate offset in the ovector, which contain PCRE2_UNSET for unset
+ appropriate offset in the ovector, which contain PCRE2_UNSET for unset
substrings, or by calling pcre2_substring_length_bynumber().
@@ -3128,7 +3119,7 @@
void pcre2_substring_free(PCRE2_UCHAR *buffer);
- To extract a substring by name, you first have to find associated num-
+ To extract a substring by name, you first have to find associated num-
ber. For example, for this pattern:
(a+)b(?<xxx>\d+)...
@@ -3136,32 +3127,32 @@
the number of the capture group called "xxx" is 2. If the name is known
to be unique (PCRE2_DUPNAMES was not set), you can find the number from
the name by calling pcre2_substring_number_from_name(). The first argu-
- ment is the compiled pattern, and the second is the name. The yield of
- the function is the group number, PCRE2_ERROR_NOSUBSTRING if there is
- no group with that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if there is
- more than one group with that name. Given the number, you can extract
- the substring directly from the ovector, or use one of the "bynumber"
+ ment is the compiled pattern, and the second is the name. The yield of
+ the function is the group number, PCRE2_ERROR_NOSUBSTRING if there is
+ no group with that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if there is
+ more than one group with that name. Given the number, you can extract
+ the substring directly from the ovector, or use one of the "bynumber"
functions described above.
- For convenience, there are also "byname" functions that correspond to
- the "bynumber" functions, the only difference being that the second
- argument is a name instead of a number. If PCRE2_DUPNAMES is set and
+ For convenience, there are also "byname" functions that correspond to
+ the "bynumber" functions, the only difference being that the second ar-
+ gument is a name instead of a number. If PCRE2_DUPNAMES is set and
there are duplicate names, these functions scan all the groups with the
- given name, and return the captured substring from the first named
+ given name, and return the captured substring from the first named
group that is set.
- If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
- returned. If all groups with the name have numbers that are greater
- than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is
- returned. If there is at least one group with a slot in the ovector,
- but no group is found to be set, PCRE2_ERROR_UNSET is returned.
+ If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
+ returned. If all groups with the name have numbers that are greater
+ than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is re-
+ turned. If there is at least one group with a slot in the ovector, but
+ no group is found to be set, PCRE2_ERROR_UNSET is returned.
Warning: If the pattern uses the (?| feature to set up multiple capture
- groups with the same number, as described in the section on duplicate
+ groups with the same number, as described in the section on duplicate
group numbers in the pcre2pattern page, you cannot use names to distin-
- guish the different capture groups, because names are not included in
- the compiled code. The matching process uses only numbers. For this
- reason, the use of different names for groups with the same number
+ guish the different capture groups, because names are not included in
+ the compiled code. The matching process uses only numbers. For this
+ reason, the use of different names for groups with the same number
causes an error at compile time.
@@ -3174,72 +3165,72 @@
PCRE2_SIZE rlength, PCRE2_UCHAR *outputbuffer,
PCRE2_SIZE *outlengthptr);
- This function calls pcre2_match() and then makes a copy of the subject
- string in outputbuffer, replacing one or more parts that were matched
+ This function calls pcre2_match() and then makes a copy of the subject
+ string in outputbuffer, replacing one or more parts that were matched
with the replacement string, whose length is supplied in rlength. This
- can be given as PCRE2_ZERO_TERMINATED for a zero-terminated string.
- The default is to perform just one replacement, but there is an option
- that requests multiple replacements (see PCRE2_SUBSTITUTE_GLOBAL below
+ can be given as PCRE2_ZERO_TERMINATED for a zero-terminated string.
+ The default is to perform just one replacement, but there is an option
+ that requests multiple replacements (see PCRE2_SUBSTITUTE_GLOBAL below
for details).
- Matches in which a \K item in a lookahead in the pattern causes the
- match to end before it starts are not supported, and give rise to an
+ Matches in which a \K item in a lookahead in the pattern causes the
+ match to end before it starts are not supported, and give rise to an
error return. For global replacements, matches in which \K in a lookbe-
- hind causes the match to start earlier than the point that was reached
+ hind causes the match to start earlier than the point that was reached
in the previous iteration are also not supported.
- The first seven arguments of pcre2_substitute() are the same as for
+ The first seven arguments of pcre2_substitute() are the same as for
pcre2_match(), except that the partial matching options are not permit-
- ted, and match_data may be passed as NULL, in which case a match data
- block is obtained and freed within this function, using memory manage-
- ment functions from the match context, if provided, or else those that
+ ted, and match_data may be passed as NULL, in which case a match data
+ block is obtained and freed within this function, using memory manage-
+ ment functions from the match context, if provided, or else those that
were used to allocate memory for the compiled code.
- If an external match_data block is provided, its contents afterwards
- are those set by the final call to pcre2_match(). For global changes,
- this will have ended in a matching error. The contents of the ovector
+ If an external match_data block is provided, its contents afterwards
+ are those set by the final call to pcre2_match(). For global changes,
+ this will have ended in a matching error. The contents of the ovector
within the match data block may or may not have been changed.
- The outlengthptr argument must point to a variable that contains the
- length, in code units, of the output buffer. If the function is suc-
- cessful, the value is updated to contain the length of the new string,
+ The outlengthptr argument must point to a variable that contains the
+ length, in code units, of the output buffer. If the function is suc-
+ cessful, the value is updated to contain the length of the new string,
excluding the trailing zero that is automatically added.
- If the function is not successful, the value set via outlengthptr
- depends on the type of error. For syntax errors in the replacement
- string, the value is the offset in the replacement string where the
- error was detected. For other errors, the value is PCRE2_UNSET by
- default. This includes the case of the output buffer being too small,
- unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which
- case the value is the minimum length needed, including space for the
- trailing zero. Note that in order to compute the required length,
- pcre2_substitute() has to simulate all the matching and copying,
- instead of giving an error return as soon as the buffer overflows. Note
- also that the length is in code units, not bytes.
+ If the function is not successful, the value set via outlengthptr de-
+ pends on the type of error. For syntax errors in the replacement
+ string, the value is the offset in the replacement string where the er-
+ ror was detected. For other errors, the value is PCRE2_UNSET by de-
+ fault. This includes the case of the output buffer being too small, un-
+ less PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which case
+ the value is the minimum length needed, including space for the trail-
+ ing zero. Note that in order to compute the required length, pcre2_sub-
+ stitute() has to simulate all the matching and copying, instead of giv-
+ ing an error return as soon as the buffer overflows. Note also that the
+ length is in code units, not bytes.
- In the replacement string, which is interpreted as a UTF string in UTF
- mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK
- option is set, a dollar character is an escape character that can spec-
- ify the insertion of characters from capture groups or names from
- (*MARK) or other control verbs in the pattern. The following forms are
- always recognized:
+ In the replacement string, which is interpreted as a UTF string in UTF
+ mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK op-
+ tion is set, a dollar character is an escape character that can specify
+ the insertion of characters from capture groups or names from (*MARK)
+ or other control verbs in the pattern. The following forms are always
+ recognized:
$$ insert a dollar character
$<n> or ${<n>} insert the contents of group <n>
$*MARK or ${*MARK} insert a control verb name
- Either a group number or a group name can be given for <n>. Curly
- brackets are required only if the following character would be inter-
+ Either a group number or a group name can be given for <n>. Curly
+ brackets are required only if the following character would be inter-
preted as part of the number or name. The number may be zero to include
- the entire matched string. For example, if the pattern a(b)c is
- matched with "=abc=" and the replacement string "+$1$0$1+", the result
+ the entire matched string. For example, if the pattern a(b)c is
+ matched with "=abc=" and the replacement string "+$1$0$1+", the result
is "=+babcb+=".
- $*MARK inserts the name from the last encountered backtracking control
- verb on the matching path that has a name. (*MARK) must always include
- a name, but the other verbs need not. For example, in the case of
+ $*MARK inserts the name from the last encountered backtracking control
+ verb on the matching path that has a name. (*MARK) must always include
+ a name, but the other verbs need not. For example, in the case of
(*MARK:A)(*PRUNE) the name inserted is "A", but for (*MARK:A)(*PRUNE:B)
- the relevant name is "B". This facility can be used to perform simple
+ the relevant name is "B". This facility can be used to perform simple
simultaneous substitutions, as this pcre2test example shows:
/(*MARK:pear)apple|(*MARK:orange)lemon/g,replace=${*MARK}
@@ -3246,19 +3237,19 @@
apple lemon
2: pear orange
- As well as the usual options for pcre2_match(), a number of additional
+ As well as the usual options for pcre2_match(), a number of additional
options can be set in the options argument of pcre2_substitute().
PCRE2_SUBSTITUTE_GLOBAL causes the function to iterate over the subject
- string, replacing every matching substring. If this option is not set,
- only the first matching substring is replaced. The search for matches
- takes place in the original subject string (that is, previous replace-
- ments do not affect it). Iteration is implemented by advancing the
- startoffset value for each search, which is always passed the entire
+ string, replacing every matching substring. If this option is not set,
+ only the first matching substring is replaced. The search for matches
+ takes place in the original subject string (that is, previous replace-
+ ments do not affect it). Iteration is implemented by advancing the
+ startoffset value for each search, which is always passed the entire
subject string. If an offset limit is set in the match context, search-
ing stops when that limit is reached.
- You can restrict the effect of a global substitution to a portion of
+ You can restrict the effect of a global substitution to a portion of
the subject string by setting either or both of startoffset and an off-
set limit. Here is a pcre2test example:
@@ -3266,68 +3257,67 @@
ABC ABC ABC ABC\=offset=3,offset_limit=12
2: ABC A!C A!C ABC
- When continuing with global substitutions after matching a substring
+ When continuing with global substitutions after matching a substring
with zero length, an attempt to find a non-empty match at the same off-
set is performed. If this is not successful, the offset is advanced by
one character except when CRLF is a valid newline sequence and the next
- two characters are CR, LF. In this case, the offset is advanced by two
+ two characters are CR, LF. In this case, the offset is advanced by two
characters.
- PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output
+ PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output
buffer is too small. The default action is to return PCRE2_ERROR_NOMEM-
- ORY immediately. If this option is set, however, pcre2_substitute()
+ ORY immediately. If this option is set, however, pcre2_substitute()
continues to go through the motions of matching and substituting (with-
- out, of course, writing anything) in order to compute the size of buf-
- fer that is needed. This value is passed back via the outlengthptr
- variable, with the result of the function still being
- PCRE2_ERROR_NOMEMORY.
+ out, of course, writing anything) in order to compute the size of buf-
+ fer that is needed. This value is passed back via the outlengthptr
+ variable, with the result of the function still being PCRE2_ER-
+ ROR_NOMEMORY.
- Passing a buffer size of zero is a permitted way of finding out how
- much memory is needed for given substitution. However, this does mean
+ Passing a buffer size of zero is a permitted way of finding out how
+ much memory is needed for given substitution. However, this does mean
that the entire operation is carried out twice. Depending on the appli-
- cation, it may be more efficient to allocate a large buffer and free
- the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER-
+ cation, it may be more efficient to allocate a large buffer and free
+ the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER-
FLOW_LENGTH.
PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capture groups that
do not appear in the pattern to be treated as unset groups. This option
- should be used with care, because it means that a typo in a group name
+ should be used with care, because it means that a typo in a group name
or number no longer causes the PCRE2_ERROR_NOSUBSTRING error.
- PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capture groups (including
- unknown groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be
- treated as empty strings when inserted as described above. If this
- option is not set, an attempt to insert an unset group causes the
- PCRE2_ERROR_UNSET error. This option does not influence the extended
- substitution syntax described below.
+ PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capture groups (including un-
+ known groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be treated
+ as empty strings when inserted as described above. If this option is
+ not set, an attempt to insert an unset group causes the PCRE2_ERROR_UN-
+ SET error. This option does not influence the extended substitution
+ syntax described below.
- PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the
- replacement string. Without this option, only the dollar character is
- special, and only the group insertion forms listed above are valid.
+ PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the
+ replacement string. Without this option, only the dollar character is
+ special, and only the group insertion forms listed above are valid.
When PCRE2_SUBSTITUTE_EXTENDED is set, two things change:
- Firstly, backslash in a replacement string is interpreted as an escape
+ Firstly, backslash in a replacement string is interpreted as an escape
character. The usual forms such as \n or \x{ddd} can be used to specify
- particular character codes, and backslash followed by any non-alphanu-
- meric character quotes that character. Extended quoting can be coded
+ particular character codes, and backslash followed by any non-alphanu-
+ meric character quotes that character. Extended quoting can be coded
using \Q...\E, exactly as in pattern strings.
- There are also four escape sequences for forcing the case of inserted
- letters. The insertion mechanism has three states: no case forcing,
+ There are also four escape sequences for forcing the case of inserted
+ letters. The insertion mechanism has three states: no case forcing,
force upper case, and force lower case. The escape sequences change the
current state: \U and \L change to upper or lower case forcing, respec-
- tively, and \E (when not terminating a \Q quoted sequence) reverts to
- no case forcing. The sequences \u and \l force the next character (if
- it is a letter) to upper or lower case, respectively, and then the
+ tively, and \E (when not terminating a \Q quoted sequence) reverts to
+ no case forcing. The sequences \u and \l force the next character (if
+ it is a letter) to upper or lower case, respectively, and then the
state automatically reverts to no case forcing. Case forcing applies to
- all inserted characters, including those from capture groups and let-
+ all inserted characters, including those from capture groups and let-
ters within \Q...\E quoted sequences.
Note that case forcing sequences such as \U...\E do not nest. For exam-
- ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
- \E has no effect. Note also that the PCRE2_ALT_BSUX and
- PCRE2_EXTRA_ALT_BSUX options do not apply to not apply to replacement
- strings.
+ ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
+ \E has no effect. Note also that the PCRE2_ALT_BSUX and PCRE2_EX-
+ TRA_ALT_BSUX options do not apply to not apply to replacement strings.
The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
flexibility to capture group substitution. The syntax is similar to
@@ -3357,8 +3347,8 @@
1: HELLO
The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
- substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause
- unknown groups in the extended syntax forms to be treated as unset.
+ substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause un-
+ known groups in the extended syntax forms to be treated as unset.
If successful, pcre2_substitute() returns the number of successful
matches. This may be zero if no matches were found, and is never
@@ -3373,8 +3363,8 @@
PCRE2_ERROR_UNSET is returned for an unset substring insertion (includ-
ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
- when the simple (non-extended) syntax is used and PCRE2_SUBSTI-
- TUTE_UNSET_EMPTY is not set.
+ when the simple (non-extended) syntax is used and PCRE2_SUBSTITUTE_UN-
+ SET_EMPTY is not set.
PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big
enough. If the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set, the size
@@ -3382,17 +3372,17 @@
does not happen by default.
PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in
- the replacement string, with more particular errors being
- PCRE2_ERROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REP-
- MISSINGBRACE (closing curly bracket not found), PCRE2_ERROR_BADSUBSTI-
- TUTION (syntax error in extended group substitution), and
- PCRE2_ERROR_BADSUBSPATTERN (the pattern match ended before it started
- or the match started earlier than the current position in the subject,
- which can happen if \K is used in an assertion).
+ the replacement string, with more particular errors being PCRE2_ER-
+ ROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REPMISSINGBRACE
+ (closing curly bracket not found), PCRE2_ERROR_BADSUBSTITUTION (syntax
+ error in extended group substitution), and PCRE2_ERROR_BADSUBSPATTERN
+ (the pattern match ended before it started or the match started earlier
+ than the current position in the subject, which can happen if \K is
+ used in an assertion).
As for all PCRE2 errors, a text message that describes the error can be
- obtained by calling the pcre2_get_error_message() function (see
- "Obtaining a textual error message" above).
+ obtained by calling the pcre2_get_error_message() function (see "Ob-
+ taining a textual error message" above).
Substitution callouts
@@ -3442,8 +3432,8 @@
If the value is zero, the replacement is accepted, and, if PCRE2_SUB-
STITUTE_GLOBAL is set, processing continues with a search for the next
- match. If the value is not zero, the current replacement is not
- accepted. If the value is greater than zero, processing continues when
+ match. If the value is not zero, the current replacement is not ac-
+ cepted. If the value is greater than zero, processing continues when
PCRE2_SUBSTITUTE_GLOBAL is set. Otherwise (the value is less than zero
or PCRE2_SUBSTITUTE_GLOBAL is not set), the the rest of the input is
copied to the output and the call to pcre2_substitute() exits, return-
@@ -3456,10 +3446,10 @@
PCRE2_SPTR name, PCRE2_SPTR *first, PCRE2_SPTR *last);
When a pattern is compiled with the PCRE2_DUPNAMES option, names for
- capture groups are not required to be unique. Duplicate names are
- always allowed for groups with the same number, created by using the
- (?| feature. Indeed, if such groups are named, they are required to use
- the same names.
+ capture groups are not required to be unique. Duplicate names are al-
+ ways allowed for groups with the same number, created by using the (?|
+ feature. Indeed, if such groups are named, they are required to use the
+ same names.
Normally, patterns that use duplicate names are such that in any one
match, only one of each set of identically-named groups participates.
@@ -3467,10 +3457,10 @@
When duplicates are present, pcre2_substring_copy_byname() and
pcre2_substring_get_byname() return the first substring corresponding
- to the given name that is set. Only if none are set is
- PCRE2_ERROR_UNSET is returned. The pcre2_substring_number_from_name()
- function returns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are
- duplicate names.
+ to the given name that is set. Only if none are set is PCRE2_ERROR_UN-
+ SET is returned. The pcre2_substring_number_from_name() function re-
+ turns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are duplicate
+ names.
If you want to get full details of all captured substrings for a given
name, you must use the pcre2_substring_nametable_scan() function. The
@@ -3557,44 +3547,43 @@
The unused bits of the options argument for pcre2_dfa_match() must be
zero. The only bits that may be set are PCRE2_ANCHORED,
- PCRE2_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL,
- PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART,
- PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, PCRE2_PARTIAL_SOFT,
- PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All but the last four of
- these are exactly the same as for pcre2_match(), so their description
- is not repeated here.
+ PCRE2_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL, PCRE2_NO-
+ TEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART, PCRE2_NO_UTF_CHECK,
+ PCRE2_PARTIAL_HARD, PCRE2_PARTIAL_SOFT, PCRE2_DFA_SHORTEST, and
+ PCRE2_DFA_RESTART. All but the last four of these are exactly the same
+ as for pcre2_match(), so their description is not repeated here.
PCRE2_PARTIAL_HARD
PCRE2_PARTIAL_SOFT
- These have the same general effect as they do for pcre2_match(), but
- the details are slightly different. When PCRE2_PARTIAL_HARD is set for
- pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the
+ These have the same general effect as they do for pcre2_match(), but
+ the details are slightly different. When PCRE2_PARTIAL_HARD is set for
+ pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the
subject is reached and there is still at least one matching possibility
that requires additional characters. This happens even if some complete
- matches have already been found. When PCRE2_PARTIAL_SOFT is set, the
- return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
- if the end of the subject is reached, there have been no complete
+ matches have already been found. When PCRE2_PARTIAL_SOFT is set, the
+ return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
+ if the end of the subject is reached, there have been no complete
matches, but there is still at least one matching possibility. The por-
- tion of the string that was inspected when the longest partial match
+ tion of the string that was inspected when the longest partial match
was found is set as the first matching string in both cases. There is a
- more detailed discussion of partial and multi-segment matching, with
+ more detailed discussion of partial and multi-segment matching, with
examples, in the pcre2partial documentation.
PCRE2_DFA_SHORTEST
- Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to
+ Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to
stop as soon as it has found one match. Because of the way the alterna-
- tive algorithm works, this is necessarily the shortest possible match
+ tive algorithm works, this is necessarily the shortest possible match
at the first possible matching point in the subject string.
PCRE2_DFA_RESTART
- When pcre2_dfa_match() returns a partial match, it is possible to call
+ When pcre2_dfa_match() returns a partial match, it is possible to call
it again, with additional subject characters, and have it continue with
the same match. The PCRE2_DFA_RESTART option requests this action; when
- it is set, the workspace and wscount options must reference the same
- vector as before because data about the match so far is left in them
+ it is set, the workspace and wscount options must reference the same
+ vector as before because data about the match so far is left in them
after a partial match. There is more discussion of this facility in the
pcre2partial documentation.
@@ -3602,8 +3591,8 @@
When pcre2_dfa_match() succeeds, it may have matched more than one sub-
string in the subject. Note, however, that all the matches from one run
- of the function start at the same point in the subject. The shorter
- matches are all initial substrings of the longer matches. For example,
+ of the function start at the same point in the subject. The shorter
+ matches are all initial substrings of the longer matches. For example,
if the pattern
<.*>
@@ -3618,80 +3607,80 @@
<something> <something else>
<something>
- On success, the yield of the function is a number greater than zero,
- which is the number of matched substrings. The offsets of the sub-
- strings are returned in the ovector, and can be extracted by number in
- the same way as for pcre2_match(), but the numbers bear no relation to
- any capture groups that may exist in the pattern, because DFA matching
+ On success, the yield of the function is a number greater than zero,
+ which is the number of matched substrings. The offsets of the sub-
+ strings are returned in the ovector, and can be extracted by number in
+ the same way as for pcre2_match(), but the numbers bear no relation to
+ any capture groups that may exist in the pattern, because DFA matching
does not support capturing.
- Calls to the convenience functions that extract substrings by name
- return the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used
- after a DFA match. The convenience functions that extract substrings by
+ Calls to the convenience functions that extract substrings by name re-
+ turn the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used af-
+ ter a DFA match. The convenience functions that extract substrings by
number never return PCRE2_ERROR_NOSUBSTRING.
- The matched strings are stored in the ovector in reverse order of
- length; that is, the longest matching string is first. If there were
- too many matches to fit into the ovector, the yield of the function is
+ The matched strings are stored in the ovector in reverse order of
+ length; that is, the longest matching string is first. If there were
+ too many matches to fit into the ovector, the yield of the function is
zero, and the vector is filled with the longest matches.
- NOTE: PCRE2's "auto-possessification" optimization usually applies to
- character repeats at the end of a pattern (as well as internally). For
- example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA
- matching, this means that only one possible match is found. If you
- really do want multiple matches in such cases, either use an ungreedy
- repeat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when
- compiling.
+ NOTE: PCRE2's "auto-possessification" optimization usually applies to
+ character repeats at the end of a pattern (as well as internally). For
+ example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA
+ matching, this means that only one possible match is found. If you re-
+ ally do want multiple matches in such cases, either use an ungreedy re-
+ peat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when com-
+ piling.
Error returns from pcre2_dfa_match()
The pcre2_dfa_match() function returns a negative number when it fails.
- Many of the errors are the same as for pcre2_match(), as described
+ Many of the errors are the same as for pcre2_match(), as described
above. There are in addition the following errors that are specific to
pcre2_dfa_match():
PCRE2_ERROR_DFA_UITEM
- This return is given if pcre2_dfa_match() encounters an item in the
- pattern that it does not support, for instance, the use of \C in a UTF
+ This return is given if pcre2_dfa_match() encounters an item in the
+ pattern that it does not support, for instance, the use of \C in a UTF
mode or a backreference.
PCRE2_ERROR_DFA_UCOND
- This return is given if pcre2_dfa_match() encounters a condition item
+ This return is given if pcre2_dfa_match() encounters a condition item
that uses a backreference for the condition, or a test for recursion in
a specific capture group. These are not supported.
PCRE2_ERROR_DFA_UINVALID_UTF
- This return is given if pcre2_dfa_match() is called for a pattern that
- was compiled with PCRE2_MATCH_INVALID_UTF. This is not supported for
+ This return is given if pcre2_dfa_match() is called for a pattern that
+ was compiled with PCRE2_MATCH_INVALID_UTF. This is not supported for
DFA matching.
PCRE2_ERROR_DFA_WSSIZE
- This return is given if pcre2_dfa_match() runs out of space in the
+ This return is given if pcre2_dfa_match() runs out of space in the
workspace vector.
PCRE2_ERROR_DFA_RECURSE
When a recursion or subroutine call is processed, the matching function
- calls itself recursively, using private memory for the ovector and
- workspace. This error is given if the internal ovector is not large
- enough. This should be extremely rare, as a vector of size 1000 is
+ calls itself recursively, using private memory for the ovector and
+ workspace. This error is given if the internal ovector is not large
+ enough. This should be extremely rare, as a vector of size 1000 is
used.
PCRE2_ERROR_DFA_BADRESTART
- When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option,
- some plausibility checks are made on the contents of the workspace,
- which should contain data about the previous partial match. If any of
+ When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option,
+ some plausibility checks are made on the contents of the workspace,
+ which should contain data about the previous partial match. If any of
these checks fail, this error is given.
SEE ALSO
- pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3),
+ pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3),
pcre2partial(3), pcre2posix(3), pcre2sample(3), pcre2unicode(3).
@@ -3721,9 +3710,9 @@
PCRE2 is distributed with a configure script that can be used to build
the library in Unix-like environments using the applications known as
Autotools. Also in the distribution are files to support building using
- CMake instead of configure. The text file README contains general
- information about building with Autotools (some of which is repeated
- below), and also has some comments about building on various operating
+ CMake instead of configure. The text file README contains general in-
+ formation about building with Autotools (some of which is repeated be-
+ low), and also has some comments about building on various operating
systems. There is a lot more information about building PCRE2 without
using Autotools (including information about using CMake and building
"by hand") in the text file called NON-AUTOTOOLS-BUILD. You should
@@ -3746,8 +3735,8 @@
compiler, as described in NON-AUTOTOOLS-BUILD.
The complete list of options for configure (which includes the standard
- ones such as the selection of the installation directory) can be
- obtained by running
+ ones such as the selection of the installation directory) can be ob-
+ tained by running
./configure --help
@@ -3804,8 +3793,8 @@
--disable-unicode
to the configure command. This setting applies to all three libraries.
- It is not possible to build one library with Unicode support, and
- another without, in the same configuration.
+ It is not possible to build one library with Unicode support, and an-
+ other without, in the same configuration.
Of itself, Unicode support does not make PCRE2 treat strings as UTF-8,
UTF-16 or UTF-32. To do that, applications that use the library can set
@@ -3831,8 +3820,8 @@
The \C escape sequence, which matches a single code unit, even in a UTF
mode, can cause unpredictable behaviour because it may leave the cur-
rent matching point in the middle of a multi-code-unit character. The
- application can lock it out by setting the PCRE2_NEVER_BACKSLASH_C
- option when calling pcre2_compile(). There is also a build-time option
+ application can lock it out by setting the PCRE2_NEVER_BACKSLASH_C op-
+ tion when calling pcre2_compile(). There is also a build-time option
--enable-never-backslash-C
@@ -3878,8 +3867,8 @@
--enable-newline-is-cr
- to the configure command. There is also an --enable-newline-is-lf
- option, which explicitly specifies linefeed as the newline character.
+ to the configure command. There is also an --enable-newline-is-lf op-
+ tion, which explicitly specifies linefeed as the newline character.
Alternatively, you can specify that line endings are to be indicated by
the two-character sequence CRLF (CR immediately followed by LF). If you
@@ -3991,8 +3980,8 @@
used, but because the size of each backtracking "frame" depends on the
number of capturing parentheses in a pattern, the amount of heap that
is used before the limit is reached varies from pattern to pattern.
- This limit was more useful in versions before 10.30, where function
- recursion was used for backtracking.
+ This limit was more useful in versions before 10.30, where function re-
+ cursion was used for backtracking.
As well as applying to pcre2_match(), the depth limit also controls the
depth of recursive function calls in pcre2_dfa_match(). These are used
@@ -4028,8 +4017,8 @@
--enable-ebcdic --disable-unicode
to the configure command. This setting implies --enable-rebuild-charta-
- bles. You should only use it if you know that you are in an EBCDIC
- environment (for example, an IBM mainframe operating system).
+ bles. You should only use it if you know that you are in an EBCDIC en-
+ vironment (for example, an IBM mainframe operating system).
It is not possible to support both EBCDIC and UTF-8 codes in the same
version of the library. Consequently, --enable-unicode and --enable-
@@ -4058,9 +4047,9 @@
erates output using local code, and another that calls an external pro-
gram or script. If --disable-pcre2grep-callout-fork is added to the
configure command, only the first kind of callout is supported; if
- --disable-pcre2grep-callout is used, all callouts are completely
- ignored. For more details of pcre2grep callouts, see the pcre2grep doc-
- umentation.
+ --disable-pcre2grep-callout is used, all callouts are completely ig-
+ nored. For more details of pcre2grep callouts, see the pcre2grep docu-
+ mentation.
PCRE2GREP OPTIONS FOR COMPRESSED FILE SUPPORT
@@ -4105,8 +4094,8 @@
--enable-pcre2test-libreadline
--enable-pcre2test-libedit
- to the configure command, pcre2test is linked with the libreadline
- orlibedit library, respectively, and when its input is from a terminal,
+ to the configure command, pcre2test is linked with the libreadline or-
+ libedit library, respectively, and when its input is from a terminal,
it reads it using the readline() function. This provides line-editing
and history facilities. Note that libreadline is GPL-licensed, so if
you distribute a binary of pcre2test linked in this way, there may be
@@ -4149,14 +4138,13 @@
--enable-valgrind
to the configure command, PCRE2 will use valgrind annotations to mark
- certain memory regions as unaddressable. This allows it to detect
- invalid memory accesses, and is mostly useful for debugging PCRE2
- itself.
+ certain memory regions as unaddressable. This allows it to detect in-
+ valid memory accesses, and is mostly useful for debugging PCRE2 itself.
CODE COVERAGE REPORTING
- If your C compiler is gcc, you can build a version of PCRE2 that can
+ If your C compiler is gcc, you can build a version of PCRE2 that can
generate a code coverage report for its test suite. To enable this, you
must install lcov version 1.6 or above. Then specify
@@ -4165,7 +4153,7 @@
to the configure command and build PCRE2 in the usual way.
Note that using ccache (a caching C compiler) is incompatible with code
- coverage reporting. If you have configured ccache to run automatically
+ coverage reporting. If you have configured ccache to run automatically
on your system, you must set the environment variable
CCACHE_DISABLE=1
@@ -4172,13 +4160,13 @@
before running make to build PCRE2, so that ccache is not used.
- When --enable-coverage is used, the following addition targets are
+ When --enable-coverage is used, the following addition targets are
added to the Makefile:
make coverage
- This creates a fresh coverage report for the PCRE2 test suite. It is
- equivalent to running "make coverage-reset", "make coverage-baseline",
+ This creates a fresh coverage report for the PCRE2 test suite. It is
+ equivalent to running "make coverage-reset", "make coverage-baseline",
"make check", and then "make coverage-report".
make coverage-reset
@@ -4195,29 +4183,29 @@
make coverage-clean-report
- This removes the generated coverage report without cleaning the cover-
+ This removes the generated coverage report without cleaning the cover-
age data itself.
make coverage-clean-data
- This removes the captured coverage data without removing the coverage
+ This removes the captured coverage data without removing the coverage
files created at compile time (*.gcno).
make coverage-clean
- This cleans all coverage data including the generated coverage report.
- For more information about code coverage, see the gcov and lcov docu-
+ This cleans all coverage data including the generated coverage report.
+ For more information about code coverage, see the gcov and lcov docu-
mentation.
DISABLING THE Z AND T FORMATTING MODIFIERS
- The C99 standard defines formatting modifiers z and t for size_t and
- ptrdiff_t values, respectively. By default, PCRE2 uses these modifiers
- in environments other than Microsoft Visual Studio when __STDC_VER-
- SION__ is defined and has a value greater than or equal to 199901L
- (indicating C99). However, there is at least one environment that
- claims to be C99 but does not support these modifiers. If
+ The C99 standard defines formatting modifiers z and t for size_t and
+ ptrdiff_t values, respectively. By default, PCRE2 uses these modifiers
+ in environments other than Microsoft Visual Studio when __STDC_VER-
+ SION__ is defined and has a value greater than or equal to 199901L (in-
+ dicating C99). However, there is at least one environment that claims
+ to be C99 but does not support these modifiers. If
--disable-percent-zt
@@ -4227,39 +4215,39 @@
SUPPORT FOR FUZZERS
- There is a special option for use by people who want to run fuzzing
+ There is a special option for use by people who want to run fuzzing
tests on PCRE2:
--enable-fuzz-support
At present this applies only to the 8-bit library. If set, it causes an
- extra library called libpcre2-fuzzsupport.a to be built, but not
- installed. This contains a single function called LLVMFuzzerTestOneIn-
- put() whose arguments are a pointer to a string and the length of the
- string. When called, this function tries to compile the string as a
- pattern, and if that succeeds, to match it. This is done both with no
- options and with some random options bits that are generated from the
+ extra library called libpcre2-fuzzsupport.a to be built, but not in-
+ stalled. This contains a single function called LLVMFuzzerTestOneIn-
+ put() whose arguments are a pointer to a string and the length of the
+ string. When called, this function tries to compile the string as a
+ pattern, and if that succeeds, to match it. This is done both with no
+ options and with some random options bits that are generated from the
string.
- Setting --enable-fuzz-support also causes a binary called pcre2fuz-
- zcheck to be created. This is normally run under valgrind or used when
+ Setting --enable-fuzz-support also causes a binary called pcre2fuz-
+ zcheck to be created. This is normally run under valgrind or used when
PCRE2 is compiled with address sanitizing enabled. It calls the fuzzing
- function and outputs information about what it is doing. The input
- strings are specified by arguments: if an argument starts with "=" the
- rest of it is a literal input string. Otherwise, it is assumed to be a
+ function and outputs information about what it is doing. The input
+ strings are specified by arguments: if an argument starts with "=" the
+ rest of it is a literal input string. Otherwise, it is assumed to be a
file name, and the contents of the file are the test string.
OBSOLETE OPTION
- In versions of PCRE2 prior to 10.30, there were two ways of handling
- backtracking in the pcre2_match() function. The default was to use the
+ In versions of PCRE2 prior to 10.30, there were two ways of handling
+ backtracking in the pcre2_match() function. The default was to use the
system stack, but if
--disable-stack-for-recursion
- was set, memory on the heap was used. From release 10.30 onwards this
- has changed (the stack is no longer used) and this option now does
+ was set, memory on the heap was used. From release 10.30 onwards this
+ has changed (the stack is no longer used) and this option now does
nothing except give a warning.
@@ -4426,8 +4414,8 @@
No match
This shows that all match attempts start at the beginning of the sub-
- ject. In other words, the pattern is anchored. You can disable this
- optimization by passing PCRE2_NO_DOTSTAR_ANCHOR to pcre2_compile(), or
+ ject. In other words, the pattern is anchored. You can disable this op-
+ timization by passing PCRE2_NO_DOTSTAR_ANCHOR to pcre2_compile(), or
starting the pattern with (*NO_DOTSTAR_ANCHOR). In this case, the out-
put changes to:
@@ -4538,10 +4526,10 @@
(the "ovector"). You may read the elements in this vector, but you must
not change any of them.
- For calls to pcre2_match(), the offset_vector field is not (since
- release 10.30) a pointer to the actual ovector that was passed to the
- matching function in the match data block. Instead it points to an
- internal ovector of a size large enough to hold all possible captured
+ For calls to pcre2_match(), the offset_vector field is not (since re-
+ lease 10.30) a pointer to the actual ovector that was passed to the
+ matching function in the match data block. Instead it points to an in-
+ ternal ovector of a size large enough to hold all possible captured
substrings in the pattern. Note that whenever a recursion or subroutine
call within a pattern completes, the capturing state is reset to what
it was before.
@@ -4554,8 +4542,8 @@
differ by one; for example, when the callout in the pattern
((a)(b))(?C2) is taken, capture_last is 1 but capture_top is 4.
- The contents of ovector[2] to ovector[<capture_top>*2-1] can be
- inspected in order to extract substrings that have been matched so far,
+ The contents of ovector[2] to ovector[<capture_top>*2-1] can be in-
+ spected in order to extract substrings that have been matched so far,
in the same way as extracting substrings after a match has completed.
The values in ovector[0] and ovector[1] are always PCRE2_UNSET because
the match is by definition not complete. Substrings that have not been
@@ -4574,8 +4562,8 @@
were passed to the matching function.
The start_match field normally contains the offset within the subject
- at which the current match attempt started. However, if the escape
- sequence \K has been encountered, this value is changed to reflect the
+ at which the current match attempt started. However, if the escape se-
+ quence \K has been encountered, this value is changed to reflect the
modified starting point. If the pattern is not anchored, the callout
function may be called several times from the same point in the pattern
for different starting points in the subject.
@@ -4649,11 +4637,10 @@
failed. If the value is less than zero, the match is abandoned, and the
matching function returns the negative value.
- Negative values should normally be chosen from the set of
- PCRE2_ERROR_xxx values. In particular, PCRE2_ERROR_NOMATCH forces a
- standard "no match" failure. The error number PCRE2_ERROR_CALLOUT is
- reserved for use by callout functions; it will never be used by PCRE2
- itself.
+ Negative values should normally be chosen from the set of PCRE2_ER-
+ ROR_xxx values. In particular, PCRE2_ERROR_NOMATCH forces a standard
+ "no match" failure. The error number PCRE2_ERROR_CALLOUT is reserved
+ for use by callout functions; it will never be used by PCRE2 itself.
CALLOUT ENUMERATION
@@ -4663,14 +4650,14 @@
void *user_data);
A script language that supports the use of string arguments in callouts
- might like to scan all the callouts in a pattern before running the
+ might like to scan all the callouts in a pattern before running the
match. This can be done by calling pcre2_callout_enumerate(). The first
- argument is a pointer to a compiled pattern, the second points to a
- callback function, and the third is arbitrary user data. The callback
- function is called for every callout in the pattern in the order in
+ argument is a pointer to a compiled pattern, the second points to a
+ callback function, and the third is arbitrary user data. The callback
+ function is called for every callout in the pattern in the order in
which they appear. Its first argument is a pointer to a callout enumer-
- ation block, and its second argument is the user_data value that was
- passed to pcre2_callout_enumerate(). The data block contains the fol-
+ ation block, and its second argument is the user_data value that was
+ passed to pcre2_callout_enumerate(). The data block contains the fol-
lowing fields:
version Block version number
@@ -4681,17 +4668,17 @@
callout_string_length Length of callout string
callout_string Points to callout string or is NULL
- The version number is currently 0. It will increase if new fields are
- ever added to the block. The remaining fields are the same as their
- namesakes in the pcre2_callout block that is used for callouts during
+ The version number is currently 0. It will increase if new fields are
+ ever added to the block. The remaining fields are the same as their
+ namesakes in the pcre2_callout block that is used for callouts during
matching, as described above.
- Note that the value of pattern_position is unique for each callout.
- However, if a callout occurs inside a group that is quantified with a
+ Note that the value of pattern_position is unique for each callout.
+ However, if a callout occurs inside a group that is quantified with a
non-zero minimum or a fixed maximum, the group is replicated inside the
- compiled pattern. For example, a pattern such as /(a){2}/ is compiled
- as if it were /(a)(a)/. This means that the callout will be enumerated
- more than once, but with the same value for pattern_position in each
+ compiled pattern. For example, a pattern such as /(a){2}/ is compiled
+ as if it were /(a)(a)/. This means that the callout will be enumerated
+ more than once, but with the same value for pattern_position in each
case.
The callback function should normally return zero. If it returns a non-
@@ -4723,9 +4710,9 @@
DIFFERENCES BETWEEN PCRE2 AND PERL
This document describes the differences in the ways that PCRE2 and Perl
- handle regular expressions. The differences described here are with
- respect to Perl versions 5.26, but as both Perl and PCRE2 are continu-
- ally changing, the information may sometimes be out of date.
+ handle regular expressions. The differences described here are with re-
+ spect to Perl versions 5.26, but as both Perl and PCRE2 are continually
+ changing, the information may sometimes be out of date.
1. PCRE2 has only a subset of Perl's Unicode support. Details of what
it does have are given in the pcre2unicode page.
@@ -4732,8 +4719,8 @@
2. Like Perl, PCRE2 allows repeat quantifiers on parenthesized asser-
tions, but they do not mean what you might think. For example, (?!a){3}
- does not assert that the next three characters are not "a". It just
- asserts that the next character is not "a" three times (in principle;
+ does not assert that the next three characters are not "a". It just as-
+ serts that the next character is not "a" three times (in principle;
PCRE2 optimizes this to run the assertion just once). Perl allows some
repeat quantifiers on other assertions, for example, \b* (but not
\b{3}), but these do not seem to have any use.
@@ -4767,11 +4754,11 @@
in between are treated as literals. However, this is slightly different
from Perl in that $ and @ are also handled as literals inside the
quotes. In Perl, they cause variable interpolation (but of course PCRE2
- does not have variables). Also, Perl does "double-quotish backslash
- interpolation" on any backslashes between \Q and \E which, its documen-
- tation says, "may lead to confusing results". PCRE2 treats a backslash
- between \Q and \E just like any other character. Note the following
- examples:
+ does not have variables). Also, Perl does "double-quotish backslash in-
+ terpolation" on any backslashes between \Q and \E which, its documenta-
+ tion says, "may lead to confusing results". PCRE2 treats a backslash
+ between \Q and \E just like any other character. Note the following ex-
+ amples:
Pattern PCRE2 matches Perl matches
@@ -4814,8 +4801,8 @@
12. There are some differences that are concerned with the settings of
captured strings when part of a pattern is repeated. For example,
- matching "aba" against the pattern /^(a(b)?)+$/ in Perl leaves $2
- unset, but in PCRE2 it is set to "b".
+ matching "aba" against the pattern /^(a(b)?)+$/ in Perl leaves $2 un-
+ set, but in PCRE2 it is set to "b".
13. PCRE2's handling of duplicate capture group numbers and names is
not as general as Perl's. This is a consequence of the fact the PCRE2
@@ -4845,10 +4832,10 @@
\p{Ll} match all letters, regardless of case, when case independence is
specified.
- 17. PCRE2 provides some extensions to the Perl regular expression
- facilities. Perl 5.10 includes new features that are not in earlier
- versions of Perl, some of which (such as named parentheses) were in
- PCRE2 for some time before. This list is with respect to Perl 5.26:
+ 17. PCRE2 provides some extensions to the Perl regular expression fa-
+ cilities. Perl 5.10 includes new features that are not in earlier ver-
+ sions of Perl, some of which (such as named parentheses) were in PCRE2
+ for some time before. This list is with respect to Perl 5.26:
(a) Although lookbehind assertions in PCRE2 must match fixed length
strings, each alternative branch of a lookbehind assertion can match a
@@ -4892,8 +4879,8 @@
changed within the pattern.
18. The Perl /a modifier restricts /d numbers to pure ascii, and the
- /aa modifier restricts /i case-insensitive matching to pure ascii,
- ignoring Unicode rules. This separation cannot be represented with
+ /aa modifier restricts /i case-insensitive matching to pure ascii, ig-
+ noring Unicode rules. This separation cannot be represented with
PCRE2_UCP.
19. Perl has different limits than PCRE2. See the pcre2limit documenta-
@@ -4986,8 +4973,8 @@
There is a limit to the size of pattern that JIT supports, imposed by
the size of machine stack that it uses. The exact rules are not docu-
- mented because they may change at any time, in particular, when new
- optimizations are introduced. If a pattern is too big, a call to
+ mented because they may change at any time, in particular, when new op-
+ timizations are introduced. If a pattern is too big, a call to
pcre2_jit_compile() returns PCRE2_ERROR_NOMEMORY.
PCRE2_JIT_COMPLETE requests the JIT compiler to generate code for com-
@@ -5013,8 +5000,8 @@
the entire compiled pattern is freed by calling pcre2_code_free().
In some circumstances you may need to call additional functions. These
- are described in the section entitled "Controlling the JIT stack"
- below.
+ are described in the section entitled "Controlling the JIT stack" be-
+ low.
There are some pcre2_match() options that are not supported by JIT, and
there are also some pattern items that JIT cannot handle. Details are
@@ -5029,8 +5016,8 @@
If the JIT compiler finds an unsupported item, no JIT data is gener-
ated. You can find out if JIT matching is available after compiling a
- pattern by calling pcre2_pattern_info() with the PCRE2_INFO_JITSIZE
- option. A non-zero result means that JIT compilation was successful. A
+ pattern by calling pcre2_pattern_info() with the PCRE2_INFO_JITSIZE op-
+ tion. A non-zero result means that JIT compilation was successful. A
result of 0 means that JIT support is not available, or the pattern was
not processed by pcre2_jit_compile(), or the JIT compiler was not able
to handle the pattern.
@@ -5039,9 +5026,9 @@
MATCHING SUBJECTS CONTAINING INVALID UTF
When a pattern is compiled with the PCRE2_UTF option, subject strings
- are normally expected to be a valid sequence of UTF code units. By
- default, this is checked at the start of matching and an error is gen-
- erated if invalid UTF is detected. The PCRE2_NO_UTF_CHECK option can be
+ are normally expected to be a valid sequence of UTF code units. By de-
+ fault, this is checked at the start of matching and an error is gener-
+ ated if invalid UTF is detected. The PCRE2_NO_UTF_CHECK option can be
passed to pcre2_match() to skip the check (for improved performance) if
you are sure that a subject string is valid. If this option is used
with an invalid string, the result is undefined.
@@ -5050,8 +5037,8 @@
UTF sequences is available. Calling pcre2_compile() with the
PCRE2_MATCH_INVALID_UTF option has two effects: it tells the inter-
preter in pcre2_match() to support invalid UTF, and, if pcre2_jit_com-
- pile() is called, the compiled JIT code also supports invalid UTF.
- Details of how this support works, in both the JIT and the interpretive
+ pile() is called, the compiled JIT code also supports invalid UTF. De-
+ tails of how this support works, in both the JIT and the interpretive
cases, is given in the pcre2unicode documentation.
There is also an obsolete option for pcre2_jit_compile() called
@@ -5096,11 +5083,11 @@
When the compiled JIT code runs, it needs a block of memory to use as a
stack. By default, it uses 32KiB on the machine stack. However, some
- large or complicated patterns need more than this. The error
- PCRE2_ERROR_JIT_STACKLIMIT is given when there is not enough stack.
- Three functions are provided for managing blocks of memory for use as
- JIT stacks. There is further discussion about the use of JIT stacks in
- the section entitled "JIT stack FAQ" below.
+ large or complicated patterns need more than this. The error PCRE2_ER-
+ ROR_JIT_STACKLIMIT is given when there is not enough stack. Three func-
+ tions are provided for managing blocks of memory for use as JIT stacks.
+ There is further discussion about the use of JIT stacks in the section
+ entitled "JIT stack FAQ" below.
The pcre2_jit_stack_create() function creates a JIT stack. Its argu-
ments are a starting size, a maximum size, and a general context (for
@@ -5144,8 +5131,8 @@
A callback function is obeyed whenever JIT code is about to be run; it
is not obeyed when pcre2_match() is called with options that are incom-
patible for JIT matching. A callback function can therefore be used to
- determine whether a match operation was executed by JIT or by the
- interpreter.
+ determine whether a match operation was executed by JIT or by the in-
+ terpreter.
You may safely use the same JIT stack for more than one pattern (either
by assigning directly or by callback), as long as the patterns are
@@ -5155,10 +5142,10 @@
stack to the one used for currently suspended match(es).
In a multithread application, if you do not specify a JIT stack, or if
- you assign or pass back NULL from a callback, that is thread-safe,
- because each thread has its own machine stack. However, if you assign
- or pass back a non-NULL JIT stack, this must be a different stack for
- each thread so that the application is thread-safe.
+ you assign or pass back NULL from a callback, that is thread-safe, be-
+ cause each thread has its own machine stack. However, if you assign or
+ pass back a non-NULL JIT stack, this must be a different stack for each
+ thread so that the application is thread-safe.
Strictly speaking, even more is allowed. You can assign the same non-
NULL stack to a match context that is used by any number of patterns,
@@ -5197,11 +5184,11 @@
(2) Why don't we simply allocate blocks of memory with malloc()?
- Modern operating systems have a nice feature: they can reserve an
- address space instead of allocating memory. We can safely allocate mem-
- ory pages inside this address space, so the stack could grow without
- moving memory data (this is important because of pointers). Thus we can
- allocate 1MiB address space, and use only a single memory page (usually
+ Modern operating systems have a nice feature: they can reserve an ad-
+ dress space instead of allocating memory. We can safely allocate memory
+ pages inside this address space, so the stack could grow without moving
+ memory data (this is important because of pointers). Thus we can allo-
+ cate 1MiB address space, and use only a single memory page (usually
4KiB) if that is enough. However, we can still grow up to 1MiB anytime
if needed.
@@ -5304,12 +5291,12 @@
matching directly instead of calling pcre2_match() (obviously only for
patterns that have been successfully processed by pcre2_jit_compile()).
- The fast path function is called pcre2_jit_match(), and it takes
- exactly the same arguments as pcre2_match(). However, the subject
- string must be specified with a length; PCRE2_ZERO_TERMINATED is not
- supported. Unsupported option bits (for example, PCRE2_ANCHORED,
- PCRE2_ENDANCHORED and PCRE2_COPY_MATCHED_SUBJECT) are ignored, as is
- the PCRE2_NO_JIT option. The return values are also the same as for
+ The fast path function is called pcre2_jit_match(), and it takes ex-
+ actly the same arguments as pcre2_match(). However, the subject string
+ must be specified with a length; PCRE2_ZERO_TERMINATED is not sup-
+ ported. Unsupported option bits (for example, PCRE2_ANCHORED, PCRE2_EN-
+ DANCHORED and PCRE2_COPY_MATCHED_SUBJECT) are ignored, as is the
+ PCRE2_NO_JIT option. The return values are also the same as for
pcre2_match(), plus PCRE2_ERROR_JIT_BADOPTION if a matching mode (par-
tial or complete) is requested that was not compiled.
@@ -5357,14 +5344,14 @@
The maximum size of a compiled pattern is approximately 64 thousand
code units for the 8-bit and 16-bit libraries if PCRE2 is compiled with
- the default internal linkage size, which is 2 bytes for these
- libraries. If you want to process regular expressions that are truly
+ the default internal linkage size, which is 2 bytes for these li-
+ braries. If you want to process regular expressions that are truly
enormous, you can compile PCRE2 with an internal linkage size of 3 or 4
(when building the 16-bit library, 3 is rounded up to 4). See the
README file in the source distribution and the pcre2build documentation
for details. In these cases the limit is substantially larger. How-
- ever, the speed of execution is slower. In the 32-bit library, the
- internal linkage size is always 4.
+ ever, the speed of execution is slower. In the 32-bit library, the in-
+ ternal linkage size is always 4.
The maximum length of a source pattern string is essentially unlimited;
it is the largest number a PCRE2_SIZE variable can hold. However, the
@@ -5371,10 +5358,10 @@
program that calls pcre2_compile() can specify a smaller limit.
The maximum length (in code units) of a subject string is one less than
- the largest number a PCRE2_SIZE variable can hold. PCRE2_SIZE is an
- unsigned integer type, usually defined as size_t. Its maximum value
- (that is ~(PCRE2_SIZE)0) is reserved as a special indicator for zero-
- terminated strings and unset offsets.
+ the largest number a PCRE2_SIZE variable can hold. PCRE2_SIZE is an un-
+ signed integer type, usually defined as size_t. Its maximum value (that
+ is ~(PCRE2_SIZE)0) is reserved as a special indicator for zero-termi-
+ nated strings and unset offsets.
All values in repeating quantifiers must be less than 65536.
@@ -5432,8 +5419,8 @@
An alternative algorithm is provided by the pcre2_dfa_match() function;
it operates in a different way, and is not Perl-compatible. This alter-
- native has advantages and disadvantages compared with the standard
- algorithm, and these are described below.
+ native has advantages and disadvantages compared with the standard al-
+ gorithm, and these are described below.
When there is only one possible way in which a given subject string can
match a pattern, the two algorithms give the same answer. A difference
@@ -5501,8 +5488,8 @@
Although the general principle of this matching algorithm is that it
scans the subject string only once, without backtracking, there is one
exception: when a lookaround assertion is encountered, the characters
- following or preceding the current point have to be independently
- inspected.
+ following or preceding the current point have to be independently in-
+ spected.
The scan continues until either the end of the subject is reached, or
there are no more unterminated paths. At this point, terminated paths
@@ -5536,9 +5523,9 @@
not supported or behave differently in the alternative matching func-
tion. Those that are not supported cause an error if encountered.
- 1. Because the algorithm finds all possible matches, the greedy or
- ungreedy nature of repetition quantifiers is not relevant (though it
- may affect auto-possessification, as just described). During matching,
+ 1. Because the algorithm finds all possible matches, the greedy or un-
+ greedy nature of repetition quantifiers is not relevant (though it may
+ affect auto-possessification, as just described). During matching,
greedy and ungreedy quantifiers are treated in exactly the same way.
However, possessive quantifiers can make a difference when what follows
could also match what is quantified, for example in a pattern like
@@ -5567,8 +5554,8 @@
5. Again for the same reason, script runs are not supported.
- 6. Because many paths through the tree may be active, the \K escape
- sequence, which resets the start of the match when encountered (but may
+ 6. Because many paths through the tree may be active, the \K escape se-
+ quence, which resets the start of the match when encountered (but may
be on some paths and not on others), is not supported.
7. Callouts are supported, but the value of the capture_top field is
@@ -5660,11 +5647,11 @@
If the application sees the user's keystrokes one by one, and can check
that what has been typed so far is potentially valid, it is able to
- raise an error as soon as a mistake is made, by beeping and not
- reflecting the character that has been typed, for example. This immedi-
- ate feedback is likely to be a better user interface than a check that
- is delayed until the entire string has been entered. Partial matching
- can also be useful when the subject string is very long and is not all
+ raise an error as soon as a mistake is made, by beeping and not re-
+ flecting the character that has been typed, for example. This immediate
+ feedback is likely to be a better user interface than a check that is
+ delayed until the entire string has been entered. Partial matching can
+ also be useful when the subject string is very long and is not all
available at once.
PCRE2 supports partial matching by means of the PCRE2_PARTIAL_SOFT and
@@ -5671,8 +5658,8 @@
PCRE2_PARTIAL_HARD options, which can be set when calling a matching
function. The difference between the two options is whether or not a
partial match is preferred to an alternative complete match, though the
- details differ between the two types of matching function. If both
- options are set, PCRE2_PARTIAL_HARD takes precedence.
+ details differ between the two types of matching function. If both op-
+ tions are set, PCRE2_PARTIAL_HARD takes precedence.
If you want to use partial matching with just-in-time optimized code,
you must call pcre2_jit_compile() with one or both of these options:
@@ -5684,8 +5671,8 @@
tial matches on the same pattern. If the appropriate JIT mode has not
been compiled, interpretive matching code is used.
- Setting a partial matching option disables two of PCRE2's standard
- optimizations. PCRE2 remembers the last literal code unit in a pattern,
+ Setting a partial matching option disables two of PCRE2's standard op-
+ timizations. PCRE2 remembers the last literal code unit in a pattern,
and abandons matching immediately if it is not present in the subject
string. This optimization cannot be used for a subject string that
might match only partially. PCRE2 also knows the minimum length of a
@@ -5808,8 +5795,8 @@
Because the DFA functions always search for all possible matches, and
there is no difference between greedy and ungreedy repetition, their
behaviour is different from the standard functions when PCRE2_PAR-
- TIAL_HARD is set. Consider the string "dog" matched against the
- ungreedy pattern shown above:
+ TIAL_HARD is set. Consider the string "dog" matched against the un-
+ greedy pattern shown above:
/dog(sbody)??/
@@ -5887,11 +5874,11 @@
to.
That means that, for an unanchored pattern, if a continued match fails,
- it is not possible to try again at a new starting point. All this
- facility is capable of doing is continuing with the previous match
- attempt. In the previous example, if the second set of data is "ug23"
- the result is no match, even though there would be a match for "aug23"
- if the entire string were given at once. Depending on the application,
+ it is not possible to try again at a new starting point. All this fa-
+ cility is capable of doing is continuing with the previous match at-
+ tempt. In the previous example, if the second set of data is "ug23" the
+ result is no match, even though there would be a match for "aug23" if
+ the entire string were given at once. Depending on the application,
this may or may not be what you want. The only way to allow for start-
ing again at the next character is to retain the matched part of the
subject and try a new complete match.
@@ -5933,8 +5920,8 @@
1. If the pattern contains a test for the beginning of a line, you need
to pass the PCRE2_NOTBOL option when the subject string for any call
- does start at the beginning of a line. There is also a PCRE2_NOTEOL
- option, but in practice when doing multi-segment matching you should be
+ does start at the beginning of a line. There is also a PCRE2_NOTEOL op-
+ tion, but in practice when doing multi-segment matching you should be
using PCRE2_PARTIAL_HARD, which includes the effect of PCRE2_NOTEOL.
2. If a pattern contains a lookbehind assertion, characters that pre-
@@ -6053,8 +6040,8 @@
1234|ABCD
where no string can be a partial match for both alternatives. This is
- not a problem if a standard matching function is used, because the
- entire match has to be rerun each time:
+ not a problem if a standard matching function is used, because the en-
+ tire match has to be rerun each time:
re> /1234|3789/
data> ABC123\=ph
@@ -6103,10 +6090,10 @@
Perl's regular expressions are described in its own documentation, and
regular expressions in general are covered in a number of books, some
- of which have copious examples. Jeffrey Friedl's "Mastering Regular
- Expressions", published by O'Reilly, covers regular expressions in
- great detail. This description of PCRE2's regular expressions is
- intended as reference material.
+ of which have copious examples. Jeffrey Friedl's "Mastering Regular Ex-
+ pressions", published by O'Reilly, covers regular expressions in great
+ detail. This description of PCRE2's regular expressions is intended as
+ reference material.
This document discusses the regular expression patterns that are sup-
ported by PCRE2 when its main matching function, pcre2_match(), is
@@ -6124,8 +6111,8 @@
set by special items at the start of a pattern. These are not Perl-com-
patible, but are provided to make these options accessible to pattern
writers who are not able to change the program that processes the pat-
- tern. Any number of these items may appear, but they must all be
- together right at the start of the pattern string, and the letters must
+ tern. Any number of these items may appear, but they must all be to-
+ gether right at the start of the pattern string, and the letters must
be in upper case.
UTF support
@@ -6144,8 +6131,8 @@
Some applications that allow their users to supply patterns may wish to
restrict them to non-UTF data for security reasons. If the
- PCRE2_NEVER_UTF option is passed to pcre2_compile(), (*UTF) is not
- allowed, and its appearance in a pattern causes an error.
+ PCRE2_NEVER_UTF option is passed to pcre2_compile(), (*UTF) is not al-
+ lowed, and its appearance in a pattern causes an error.
Unicode property support
@@ -6165,8 +6152,8 @@
Starting a pattern with (*NOTEMPTY) or (*NOTEMPTY_ATSTART) has the same
effect as passing the PCRE2_NOTEMPTY or PCRE2_NOTEMPTY_ATSTART option
to whichever matching function is subsequently called to match the pat-
- tern. These options lock out the matching of empty strings, either
- entirely, or only at the start of the subject.
+ tern. These options lock out the matching of empty strings, either en-
+ tirely, or only at the start of the subject.
Disabling auto-possessification
@@ -6258,8 +6245,8 @@
(*NUL) the NUL character (binary zero)
These override the default and the options given to the compiling func-
- tion. For example, on a Unix system where LF is the default newline
- sequence, the pattern
+ tion. For example, on a Unix system where LF is the default newline se-
+ quence, the pattern
(*CR)a.b
@@ -6271,8 +6258,8 @@
tions are true. It also affects the interpretation of the dot metachar-
acter when PCRE2_DOTALL is not set, and the behaviour of \N when not
followed by an opening brace. However, it does not affect what the \R
- escape sequence matches. By default, this is any Unicode newline
- sequence, for Perl compatibility. However, this can be changed; see the
+ escape sequence matches. By default, this is any Unicode newline se-
+ quence, for Perl compatibility. However, this can be changed; see the
next section and the description of \R in the section entitled "Newline
sequences" below. A change of \R setting can be combined with a change
of newline convention.
@@ -6430,9 +6417,9 @@
as \x{dc} or \334. However, using the braced versions does make such
sequences easier to read.
- Support is available for some ECMAScript (aka JavaScript) escape
- sequences via two compile-time options. If PCRE2_ALT_BSUX is set, the
- sequence \x followed by { is not recognized. Only if \x is followed by
+ Support is available for some ECMAScript (aka JavaScript) escape se-
+ quences via two compile-time options. If PCRE2_ALT_BSUX is set, the se-
+ quence \x followed by { is not recognized. Only if \x is followed by
two hexadecimal digits is it recognized as a character escape. Other-
wise it is interpreted as a literal "x" character. In this mode, sup-
port for code points greater than 256 is provided by \u, which must be
@@ -6439,10 +6426,10 @@
followed by four hexadecimal digits; otherwise it is interpreted as a
literal "u" character.
- PCRE2_EXTRA_ALT_BSUX has the same effect as PCRE2_ALT_BSUX and, in
- addition, \u{hhh..} is recognized as the character specified by hexa-
- decimal code point. There may be any number of hexadecimal digits.
- This syntax is from ECMAScript 6.
+ PCRE2_EXTRA_ALT_BSUX has the same effect as PCRE2_ALT_BSUX and, in ad-
+ dition, \u{hhh..} is recognized as the character specified by hexadeci-
+ mal code point. There may be any number of hexadecimal digits. This
+ syntax is from ECMAScript 6.
The \N{U+hhh..} escape sequence is recognized only when PCRE2 is oper-
ating in UTF mode. Perl also uses \N{name} to specify characters by
@@ -6450,8 +6437,8 @@
followed by an opening brace (curly bracket) it has an entirely differ-
ent meaning, matching any character that is not a newline.
- There are some legacy applications where the escape sequence \r is
- expected to match a newline. If the PCRE2_EXTRA_ESCAPED_CR_IS_LF option
+ There are some legacy applications where the escape sequence \r is ex-
+ pected to match a newline. If the PCRE2_EXTRA_ESCAPED_CR_IS_LF option
is set, \r in a pattern is converted to \n so that it matches a LF
(linefeed) instead of a CR (carriage return) character.
@@ -6469,8 +6456,8 @@
one of @, [, \, ], ^, _, or ?. Any other character provokes a compile-
time error. The sequence \c@ encodes character code 0; after \c the
letters (in either case) encode characters 1-26 (hex 01 to hex 1A); [,
- \, ], ^, and _ encode characters 27-31 (hex 1B to hex 1F), and \c?
- becomes either 255 (hex FF) or 95 (hex 5F).
+ \, ], ^, and _ encode characters 27-31 (hex 1B to hex 1F), and \c? be-
+ comes either 255 (hex FF) or 95 (hex 5F).
Thus, apart from \c?, these escapes generate the same character code
values as they do in an ASCII environment, though the meanings of the
@@ -6486,8 +6473,8 @@
95; otherwise it generates 255.
After \0 up to two further octal digits are read. If there are fewer
- than two digits, just those that are present are used. Thus the
- sequence \0\x\015 specifies two binary zeros followed by a CR character
+ than two digits, just those that are present are used. Thus the se-
+ quence \0\x\015 specifies two binary zeros followed by a CR character
(code value 13). Make sure you supply two digits after the initial zero
if the pattern character that follows is itself an octal digit.
@@ -6570,14 +6557,14 @@
In Perl, the sequences \F, \l, \L, \u, and \U are recognized by its
string handler and used to modify the case of following characters. By
default, PCRE2 does not support these escape sequences in patterns.
- However, if either of the PCRE2_ALT_BSUX or PCRE2_EXTRA_ALT_BSUX
- options is set, \U matches a "U" character, and \u can be used to
- define a character by code point, as described above.
+ However, if either of the PCRE2_ALT_BSUX or PCRE2_EXTRA_ALT_BSUX op-
+ tions is set, \U matches a "U" character, and \u can be used to define
+ a character by code point, as described above.
Absolute and relative backreferences
- The sequence \g followed by a signed or unsigned number, optionally
- enclosed in braces, is an absolute or relative backreference. A named
+ The sequence \g followed by a signed or unsigned number, optionally en-
+ closed in braces, is an absolute or relative backreference. A named
backreference can be coded as \g{name}. Backreferences are discussed
later, following the discussion of parenthesized groups.
@@ -6622,8 +6609,8 @@
match.
The default \s characters are HT (9), LF (10), VT (11), FF (12), CR
- (13), and space (32), which are defined as white space in the "C"
- locale. This list may vary if locale-specific matching is taking place.
+ (13), and space (32), which are defined as white space in the "C" lo-
+ cale. This list may vary if locale-specific matching is taking place.
For example, in some locales the "non-breaking space" character (\xA0)
is recognized as white space, and in others the VT character is not.
@@ -6701,8 +6688,8 @@
(?>\r\n|\n|\x0b|\f|\r|\x85)
- This is an example of an "atomic group", details of which are given
- below. This particular group matches either the two-character sequence
+ This is an example of an "atomic group", details of which are given be-
+ low. This particular group matches either the two-character sequence
CR followed by LF, or one of the single characters LF (linefeed,
U+000A), VT (vertical tab, U+000B), FF (form feed, U+000C), CR (car-
riage return, U+000D), or NEL (next line, U+0085). Because this is an
@@ -6729,14 +6716,14 @@
tion. Note that these special settings, which are not Perl-compatible,
are recognized only at the very start of a pattern, and that they must
be in upper case. If more than one of them is present, the last one is
- used. They can be combined with a change of newline convention; for
- example, a pattern can start with:
+ used. They can be combined with a change of newline convention; for ex-
+ ample, a pattern can start with:
(*ANY)(*BSR_ANYCRLF)
They can also be combined with the (*UTF) or (*UCP) special sequences.
- Inside a character class, \R is treated as an unrecognized escape
- sequence, and causes an error.
+ Inside a character class, \R is treated as an unrecognized escape se-
+ quence, and causes an error.
Unicode character properties
@@ -6746,8 +6733,8 @@
non-UTF modes these sequences are of course limited to testing charac-
ters whose code points are less than U+0100 and U+10000, respectively.
In 32-bit non-UTF mode, code points greater than 0x10ffff (the Unicode
- limit) may be encountered. These are all treated as being in the
- Unknown script and with an unassigned type. The extra escape sequences
+ limit) may be encountered. These are all treated as being in the Un-
+ known script and with an unassigned type. The extra escape sequences
are:
\p{xx} a character with the xx property
@@ -6779,35 +6766,34 @@
Braille, Buginese, Buhid, Canadian_Aboriginal, Carian, Caucasian_Alba-
nian, Chakma, Cham, Cherokee, Common, Coptic, Cuneiform, Cypriot,
Cyrillic, Deseret, Devanagari, Dogra, Duployan, Egyptian_Hieroglyphs,
- Elbasan, Ethiopic, Georgian, Glagolitic, Gothic, Grantha, Greek,
- Gujarati, Gunjala_Gondi, Gurmukhi, Han, Hangul, Hanifi_Rohingya,
- Hanunoo, Hatran, Hebrew, Hiragana, Imperial_Aramaic, Inherited,
- Inscriptional_Pahlavi, Inscriptional_Parthian, Javanese, Kaithi, Kan-
- nada, Katakana, Kayah_Li, Kharoshthi, Khmer, Khojki, Khudawadi, Lao,
- Latin, Lepcha, Limbu, Linear_A, Linear_B, Lisu, Lycian, Lydian, Maha-
- jani, Makasar, Malayalam, Mandaic, Manichaean, Marchen, Masaram_Gondi,
- Medefaidrin, Meetei_Mayek, Mende_Kikakui, Meroitic_Cursive,
- Meroitic_Hieroglyphs, Miao, Modi, Mongolian, Mro, Multani, Myanmar,
- Nabataean, New_Tai_Lue, Newa, Nko, Nushu, Ogham, Ol_Chiki, Old_Hungar-
- ian, Old_Italic, Old_North_Arabian, Old_Permic, Old_Persian, Old_Sog-
- dian, Old_South_Arabian, Old_Turkic, Oriya, Osage, Osmanya,
- Pahawh_Hmong, Palmyrene, Pau_Cin_Hau, Phags_Pa, Phoenician,
- Psalter_Pahlavi, Rejang, Runic, Samaritan, Saurashtra, Sharada, Sha-
- vian, Siddham, SignWriting, Sinhala, Sogdian, Sora_Sompeng, Soyombo,
- Sundanese, Syloti_Nagri, Syriac, Tagalog, Tagbanwa, Tai_Le, Tai_Tham,
- Tai_Viet, Takri, Tamil, Tangut, Telugu, Thaana, Thai, Tibetan, Tifi-
- nagh, Tirhuta, Ugaritic, Unknown, Vai, Warang_Citi, Yi, Zan-
- abazar_Square.
+ Elbasan, Ethiopic, Georgian, Glagolitic, Gothic, Grantha, Greek, Gu-
+ jarati, Gunjala_Gondi, Gurmukhi, Han, Hangul, Hanifi_Rohingya, Hanunoo,
+ Hatran, Hebrew, Hiragana, Imperial_Aramaic, Inherited, Inscrip-
+ tional_Pahlavi, Inscriptional_Parthian, Javanese, Kaithi, Kannada,
+ Katakana, Kayah_Li, Kharoshthi, Khmer, Khojki, Khudawadi, Lao, Latin,
+ Lepcha, Limbu, Linear_A, Linear_B, Lisu, Lycian, Lydian, Mahajani,
+ Makasar, Malayalam, Mandaic, Manichaean, Marchen, Masaram_Gondi, Mede-
+ faidrin, Meetei_Mayek, Mende_Kikakui, Meroitic_Cursive, Meroitic_Hiero-
+ glyphs, Miao, Modi, Mongolian, Mro, Multani, Myanmar, Nabataean,
+ New_Tai_Lue, Newa, Nko, Nushu, Ogham, Ol_Chiki, Old_Hungarian,
+ Old_Italic, Old_North_Arabian, Old_Permic, Old_Persian, Old_Sogdian,
+ Old_South_Arabian, Old_Turkic, Oriya, Osage, Osmanya, Pahawh_Hmong,
+ Palmyrene, Pau_Cin_Hau, Phags_Pa, Phoenician, Psalter_Pahlavi, Rejang,
+ Runic, Samaritan, Saurashtra, Sharada, Shavian, Siddham, SignWriting,
+ Sinhala, Sogdian, Sora_Sompeng, Soyombo, Sundanese, Syloti_Nagri, Syr-
+ iac, Tagalog, Tagbanwa, Tai_Le, Tai_Tham, Tai_Viet, Takri, Tamil,
+ Tangut, Telugu, Thaana, Thai, Tibetan, Tifinagh, Tirhuta, Ugaritic, Un-
+ known, Vai, Warang_Citi, Yi, Zanabazar_Square.
Each character has exactly one Unicode general category property, spec-
- ified by a two-letter abbreviation. For compatibility with Perl, nega-
- tion can be specified by including a circumflex between the opening
- brace and the property name. For example, \p{^Lu} is the same as
+ ified by a two-letter abbreviation. For compatibility with Perl, nega-
+ tion can be specified by including a circumflex between the opening
+ brace and the property name. For example, \p{^Lu} is the same as
\P{Lu}.
If only one letter is specified with \p or \P, it includes all the gen-
- eral category properties that start with that letter. In this case, in
- the absence of negation, the curly brackets in the escape sequence are
+ eral category properties that start with that letter. In this case, in
+ the absence of negation, the curly brackets in the escape sequence are
optional; these two examples have the same effect:
\p{L}
@@ -6859,20 +6845,20 @@
Zp Paragraph separator
Zs Space separator
- The special property L& is also supported: it matches a character that
- has the Lu, Ll, or Lt property, in other words, a letter that is not
+ The special property L& is also supported: it matches a character that
+ has the Lu, Ll, or Lt property, in other words, a letter that is not
classified as a modifier or "other".
- The Cs (Surrogate) property applies only to characters whose code
- points are in the range U+D800 to U+DFFF. These characters are no dif-
- ferent to any other character when PCRE2 is not in UTF mode (using the
- 16-bit or 32-bit library). However, they are not valid in Unicode
+ The Cs (Surrogate) property applies only to characters whose code
+ points are in the range U+D800 to U+DFFF. These characters are no dif-
+ ferent to any other character when PCRE2 is not in UTF mode (using the
+ 16-bit or 32-bit library). However, they are not valid in Unicode
strings and so cannot be tested by PCRE2 in UTF mode, unless UTF valid-
- ity checking has been turned off (see the discussion of
+ ity checking has been turned off (see the discussion of
PCRE2_NO_UTF_CHECK in the pcre2api page).
- The long synonyms for property names that Perl supports (such as
- \p{Letter}) are not supported by PCRE2, nor is it permitted to prefix
+ The long synonyms for property names that Perl supports (such as
+ \p{Letter}) are not supported by PCRE2, nor is it permitted to prefix
any of these properties with "Is".
No character that is in the Unicode table has the Cn (unassigned) prop-
@@ -6879,68 +6865,68 @@
erty. Instead, this property is assumed for any code point that is not
in the Unicode table.
- Specifying caseless matching does not affect these escape sequences.
- For example, \p{Lu} always matches only upper case letters. This is
+ Specifying caseless matching does not affect these escape sequences.
+ For example, \p{Lu} always matches only upper case letters. This is
different from the behaviour of current versions of Perl.
- Matching characters by Unicode property is not fast, because PCRE2 has
- to do a multistage table lookup in order to find a character's prop-
+ Matching characters by Unicode property is not fast, because PCRE2 has
+ to do a multistage table lookup in order to find a character's prop-
erty. That is why the traditional escape sequences such as \d and \w do
- not use Unicode properties in PCRE2 by default, though you can make
- them do so by setting the PCRE2_UCP option or by starting the pattern
+ not use Unicode properties in PCRE2 by default, though you can make
+ them do so by setting the PCRE2_UCP option or by starting the pattern
with (*UCP).
Extended grapheme clusters
- The \X escape matches any number of Unicode characters that form an
+ The \X escape matches any number of Unicode characters that form an
"extended grapheme cluster", and treats the sequence as an atomic group
- (see below). Unicode supports various kinds of composite character by
- giving each character a grapheme breaking property, and having rules
+ (see below). Unicode supports various kinds of composite character by
+ giving each character a grapheme breaking property, and having rules
that use these properties to define the boundaries of extended grapheme
- clusters. The rules are defined in Unicode Standard Annex 29, "Unicode
- Text Segmentation". Unicode 11.0.0 abandoned the use of some previous
- properties that had been used for emojis. Instead it introduced vari-
- ous emoji-specific properties. PCRE2 uses only the Extended Picto-
+ clusters. The rules are defined in Unicode Standard Annex 29, "Unicode
+ Text Segmentation". Unicode 11.0.0 abandoned the use of some previous
+ properties that had been used for emojis. Instead it introduced vari-
+ ous emoji-specific properties. PCRE2 uses only the Extended Picto-
graphic property.
- \X always matches at least one character. Then it decides whether to
+ \X always matches at least one character. Then it decides whether to
add additional characters according to the following rules for ending a
cluster:
1. End at the end of the subject string.
- 2. Do not end between CR and LF; otherwise end after any control char-
+ 2. Do not end between CR and LF; otherwise end after any control char-
acter.
- 3. Do not break Hangul (a Korean script) syllable sequences. Hangul
- characters are of five types: L, V, T, LV, and LVT. An L character may
- be followed by an L, V, LV, or LVT character; an LV or V character may
+ 3. Do not break Hangul (a Korean script) syllable sequences. Hangul
+ characters are of five types: L, V, T, LV, and LVT. An L character may
+ be followed by an L, V, LV, or LVT character; an LV or V character may
be followed by a V or T character; an LVT or T character may be follwed
only by a T character.
- 4. Do not end before extending characters or spacing marks or the
- "zero-width joiner" character. Characters with the "mark" property
- always have the "extend" grapheme breaking property.
+ 4. Do not end before extending characters or spacing marks or the
+ "zero-width joiner" character. Characters with the "mark" property al-
+ ways have the "extend" grapheme breaking property.
5. Do not end after prepend characters.
6. Do not break within emoji modifier sequences or emoji zwj sequences.
That is, do not break between characters with the Extended_Pictographic
- property. Extend and ZWJ characters are allowed between the charac-
+ property. Extend and ZWJ characters are allowed between the charac-
ters.
- 7. Do not break within emoji flag sequences. That is, do not break
- between regional indicator (RI) characters if there are an odd number
- of RI characters before the break point.
+ 7. Do not break within emoji flag sequences. That is, do not break be-
+ tween regional indicator (RI) characters if there are an odd number of
+ RI characters before the break point.
8. Otherwise, end the cluster.
PCRE2's additional properties
- As well as the standard Unicode properties described above, PCRE2 sup-
- ports four more that make it possible to convert traditional escape
- sequences such as \w and \s to use Unicode properties. PCRE2 uses these
- non-standard, non-Perl properties internally when PCRE2_UCP is set.
+ As well as the standard Unicode properties described above, PCRE2 sup-
+ ports four more that make it possible to convert traditional escape se-
+ quences such as \w and \s to use Unicode properties. PCRE2 uses these
+ non-standard, non-Perl properties internally when PCRE2_UCP is set.
However, they may also be used explicitly. These properties are:
Xan Any alphanumeric character
@@ -6948,42 +6934,42 @@
Xsp Any Perl space character
Xwd Any Perl "word" character
- Xan matches characters that have either the L (letter) or the N (num-
- ber) property. Xps matches the characters tab, linefeed, vertical tab,
- form feed, or carriage return, and any other character that has the Z
- (separator) property. Xsp is the same as Xps; in PCRE1 it used to
- exclude vertical tab, for Perl compatibility, but Perl changed. Xwd
+ Xan matches characters that have either the L (letter) or the N (num-
+ ber) property. Xps matches the characters tab, linefeed, vertical tab,
+ form feed, or carriage return, and any other character that has the Z
+ (separator) property. Xsp is the same as Xps; in PCRE1 it used to ex-
+ clude vertical tab, for Perl compatibility, but Perl changed. Xwd
matches the same characters as Xan, plus underscore.
- There is another non-standard property, Xuc, which matches any charac-
- ter that can be represented by a Universal Character Name in C++ and
- other programming languages. These are the characters $, @, ` (grave
- accent), and all characters with Unicode code points greater than or
- equal to U+00A0, except for the surrogates U+D800 to U+DFFF. Note that
- most base (ASCII) characters are excluded. (Universal Character Names
- are of the form \uHHHH or \UHHHHHHHH where H is a hexadecimal digit.
+ There is another non-standard property, Xuc, which matches any charac-
+ ter that can be represented by a Universal Character Name in C++ and
+ other programming languages. These are the characters $, @, ` (grave
+ accent), and all characters with Unicode code points greater than or
+ equal to U+00A0, except for the surrogates U+D800 to U+DFFF. Note that
+ most base (ASCII) characters are excluded. (Universal Character Names
+ are of the form \uHHHH or \UHHHHHHHH where H is a hexadecimal digit.
Note that the Xuc property does not match these sequences but the char-
acters that they represent.)
Resetting the match start
- In normal use, the escape sequence \K causes any previously matched
- characters not to be included in the final matched sequence that is
- returned. For example, the pattern:
+ In normal use, the escape sequence \K causes any previously matched
+ characters not to be included in the final matched sequence that is re-
+ turned. For example, the pattern:
foo\Kbar
- matches "foobar", but reports that it has matched "bar". \K does not
+ matches "foobar", but reports that it has matched "bar". \K does not
interact with anchoring in any way. The pattern:
^foo\Kbar
- matches only when the subject begins with "foobar" (in single line
- mode), though it again reports the matched string as "bar". This fea-
- ture is similar to a lookbehind assertion (described below). However,
- in this case, the part of the subject before the real match does not
- have to be of fixed length, as lookbehind assertions do. The use of \K
- does not interfere with the setting of captured substrings. For exam-
+ matches only when the subject begins with "foobar" (in single line
+ mode), though it again reports the matched string as "bar". This fea-
+ ture is similar to a lookbehind assertion (described below). However,
+ in this case, the part of the subject before the real match does not
+ have to be of fixed length, as lookbehind assertions do. The use of \K
+ does not interfere with the setting of captured substrings. For exam-
ple, when the pattern
(foo)\Kbar
@@ -6990,27 +6976,27 @@
matches "foobar", the first substring is still set to "foo".
- Perl documents that the use of \K within assertions is "not well
- defined". In PCRE2, \K is acted upon when it occurs inside positive
- assertions, but is ignored in negative assertions. Note that when a
- pattern such as (?=ab\K) matches, the reported start of the match can
- be greater than the end of the match. Using \K in a lookbehind asser-
- tion at the start of a pattern can also lead to odd effects. For exam-
- ple, consider this pattern:
+ Perl documents that the use of \K within assertions is "not well de-
+ fined". In PCRE2, \K is acted upon when it occurs inside positive as-
+ sertions, but is ignored in negative assertions. Note that when a pat-
+ tern such as (?=ab\K) matches, the reported start of the match can be
+ greater than the end of the match. Using \K in a lookbehind assertion
+ at the start of a pattern can also lead to odd effects. For example,
+ consider this pattern:
(?<=\Kfoo)bar
- If the subject is "foobar", a call to pcre2_match() with a starting
- offset of 3 succeeds and reports the matching string as "foobar", that
- is, the start of the reported match is earlier than where the match
+ If the subject is "foobar", a call to pcre2_match() with a starting
+ offset of 3 succeeds and reports the matching string as "foobar", that
+ is, the start of the reported match is earlier than where the match
started.
Simple assertions
- The final use of backslash is for certain simple assertions. An asser-
- tion specifies a condition that has to be met at a particular point in
- a match, without consuming any characters from the subject string. The
- use of groups for more complicated assertions is described below. The
+ The final use of backslash is for certain simple assertions. An asser-
+ tion specifies a condition that has to be met at a particular point in
+ a match, without consuming any characters from the subject string. The
+ use of groups for more complicated assertions is described below. The
backslashed assertions are:
\b matches at a word boundary
@@ -7021,48 +7007,48 @@
\z matches only at the end of the subject
\G matches at the first matching position in the subject
- Inside a character class, \b has a different meaning; it matches the
- backspace character. If any other of these assertions appears in a
+ Inside a character class, \b has a different meaning; it matches the
+ backspace character. If any other of these assertions appears in a
character class, an "invalid escape sequence" error is generated.
- A word boundary is a position in the subject string where the current
- character and the previous character do not both match \w or \W (i.e.
- one matches \w and the other matches \W), or the start or end of the
- string if the first or last character matches \w, respectively. When
- PCRE2 is built with Unicode support, the meanings of \w and \W can be
- changed by setting the PCRE2_UCP option. When this is done, it also
- affects \b and \B. Neither PCRE2 nor Perl has a separate "start of
- word" or "end of word" metasequence. However, whatever follows \b nor-
- mally determines which it is. For example, the fragment \ba matches "a"
- at the start of a word.
+ A word boundary is a position in the subject string where the current
+ character and the previous character do not both match \w or \W (i.e.
+ one matches \w and the other matches \W), or the start or end of the
+ string if the first or last character matches \w, respectively. When
+ PCRE2 is built with Unicode support, the meanings of \w and \W can be
+ changed by setting the PCRE2_UCP option. When this is done, it also af-
+ fects \b and \B. Neither PCRE2 nor Perl has a separate "start of word"
+ or "end of word" metasequence. However, whatever follows \b normally
+ determines which it is. For example, the fragment \ba matches "a" at
+ the start of a word.
- The \A, \Z, and \z assertions differ from the traditional circumflex
+ The \A, \Z, and \z assertions differ from the traditional circumflex
and dollar (described in the next section) in that they only ever match
- at the very start and end of the subject string, whatever options are
- set. Thus, they are independent of multiline mode. These three asser-
- tions are not affected by the PCRE2_NOTBOL or PCRE2_NOTEOL options,
- which affect only the behaviour of the circumflex and dollar metachar-
- acters. However, if the startoffset argument of pcre2_match() is non-
- zero, indicating that matching is to start at a point other than the
- beginning of the subject, \A can never match. The difference between
- \Z and \z is that \Z matches before a newline at the end of the string
+ at the very start and end of the subject string, whatever options are
+ set. Thus, they are independent of multiline mode. These three asser-
+ tions are not affected by the PCRE2_NOTBOL or PCRE2_NOTEOL options,
+ which affect only the behaviour of the circumflex and dollar metachar-
+ acters. However, if the startoffset argument of pcre2_match() is non-
+ zero, indicating that matching is to start at a point other than the
+ beginning of the subject, \A can never match. The difference between
+ \Z and \z is that \Z matches before a newline at the end of the string
as well as at the very end, whereas \z matches only at the end.
- The \G assertion is true only when the current matching position is at
- the start point of the matching process, as specified by the startoff-
- set argument of pcre2_match(). It differs from \A when the value of
- startoffset is non-zero. By calling pcre2_match() multiple times with
- appropriate arguments, you can mimic Perl's /g option, and it is in
+ The \G assertion is true only when the current matching position is at
+ the start point of the matching process, as specified by the startoff-
+ set argument of pcre2_match(). It differs from \A when the value of
+ startoffset is non-zero. By calling pcre2_match() multiple times with
+ appropriate arguments, you can mimic Perl's /g option, and it is in
this kind of implementation where \G can be useful.
- Note, however, that PCRE2's implementation of \G, being true at the
- starting character of the matching process, is subtly different from
- Perl's, which defines it as true at the end of the previous match. In
- Perl, these can be different when the previously matched string was
+ Note, however, that PCRE2's implementation of \G, being true at the
+ starting character of the matching process, is subtly different from
+ Perl's, which defines it as true at the end of the previous match. In
+ Perl, these can be different when the previously matched string was
empty. Because PCRE2 does just one match at a time, it cannot reproduce
this behaviour.
- If all the alternatives of a pattern begin with \G, the expression is
+ If all the alternatives of a pattern begin with \G, the expression is
anchored to the starting match position, and the "anchored" flag is set
in the compiled regular expression.
@@ -7069,70 +7055,70 @@
CIRCUMFLEX AND DOLLAR
- The circumflex and dollar metacharacters are zero-width assertions.
- That is, they test for a particular condition being true without con-
+ The circumflex and dollar metacharacters are zero-width assertions.
+ That is, they test for a particular condition being true without con-
suming any characters from the subject string. These two metacharacters
- are concerned with matching the starts and ends of lines. If the new-
- line convention is set so that only the two-character sequence CRLF is
- recognized as a newline, isolated CR and LF characters are treated as
+ are concerned with matching the starts and ends of lines. If the new-
+ line convention is set so that only the two-character sequence CRLF is
+ recognized as a newline, isolated CR and LF characters are treated as
ordinary data characters, and are not recognized as newlines.
Outside a character class, in the default matching mode, the circumflex
- character is an assertion that is true only if the current matching
- point is at the start of the subject string. If the startoffset argu-
- ment of pcre2_match() is non-zero, or if PCRE2_NOTBOL is set, circum-
- flex can never match if the PCRE2_MULTILINE option is unset. Inside a
- character class, circumflex has an entirely different meaning (see
- below).
+ character is an assertion that is true only if the current matching
+ point is at the start of the subject string. If the startoffset argu-
+ ment of pcre2_match() is non-zero, or if PCRE2_NOTBOL is set, circum-
+ flex can never match if the PCRE2_MULTILINE option is unset. Inside a
+ character class, circumflex has an entirely different meaning (see be-
+ low).
- Circumflex need not be the first character of the pattern if a number
- of alternatives are involved, but it should be the first thing in each
- alternative in which it appears if the pattern is ever to match that
- branch. If all possible alternatives start with a circumflex, that is,
- if the pattern is constrained to match only at the start of the sub-
- ject, it is said to be an "anchored" pattern. (There are also other
+ Circumflex need not be the first character of the pattern if a number
+ of alternatives are involved, but it should be the first thing in each
+ alternative in which it appears if the pattern is ever to match that
+ branch. If all possible alternatives start with a circumflex, that is,
+ if the pattern is constrained to match only at the start of the sub-
+ ject, it is said to be an "anchored" pattern. (There are also other
constructs that can cause a pattern to be anchored.)
- The dollar character is an assertion that is true only if the current
- matching point is at the end of the subject string, or immediately
- before a newline at the end of the string (by default), unless
- PCRE2_NOTEOL is set. Note, however, that it does not actually match the
- newline. Dollar need not be the last character of the pattern if a num-
- ber of alternatives are involved, but it should be the last item in any
- branch in which it appears. Dollar has no special meaning in a charac-
+ The dollar character is an assertion that is true only if the current
+ matching point is at the end of the subject string, or immediately be-
+ fore a newline at the end of the string (by default), unless PCRE2_NO-
+ TEOL is set. Note, however, that it does not actually match the new-
+ line. Dollar need not be the last character of the pattern if a number
+ of alternatives are involved, but it should be the last item in any
+ branch in which it appears. Dollar has no special meaning in a charac-
ter class.
- The meaning of dollar can be changed so that it matches only at the
- very end of the string, by setting the PCRE2_DOLLAR_ENDONLY option at
+ The meaning of dollar can be changed so that it matches only at the
+ very end of the string, by setting the PCRE2_DOLLAR_ENDONLY option at
compile time. This does not affect the \Z assertion.
The meanings of the circumflex and dollar metacharacters are changed if
- the PCRE2_MULTILINE option is set. When this is the case, a dollar
- character matches before any newlines in the string, as well as at the
- very end, and a circumflex matches immediately after internal newlines
- as well as at the start of the subject string. It does not match after
- a newline that ends the string, for compatibility with Perl. However,
+ the PCRE2_MULTILINE option is set. When this is the case, a dollar
+ character matches before any newlines in the string, as well as at the
+ very end, and a circumflex matches immediately after internal newlines
+ as well as at the start of the subject string. It does not match after
+ a newline that ends the string, for compatibility with Perl. However,
this can be changed by setting the PCRE2_ALT_CIRCUMFLEX option.
- For example, the pattern /^abc$/ matches the subject string "def\nabc"
- (where \n represents a newline) in multiline mode, but not otherwise.
- Consequently, patterns that are anchored in single line mode because
- all branches start with ^ are not anchored in multiline mode, and a
- match for circumflex is possible when the startoffset argument of
- pcre2_match() is non-zero. The PCRE2_DOLLAR_ENDONLY option is ignored
+ For example, the pattern /^abc$/ matches the subject string "def\nabc"
+ (where \n represents a newline) in multiline mode, but not otherwise.
+ Consequently, patterns that are anchored in single line mode because
+ all branches start with ^ are not anchored in multiline mode, and a
+ match for circumflex is possible when the startoffset argument of
+ pcre2_match() is non-zero. The PCRE2_DOLLAR_ENDONLY option is ignored
if PCRE2_MULTILINE is set.
- When the newline convention (see "Newline conventions" below) recog-
- nizes the two-character sequence CRLF as a newline, this is preferred,
- even if the single characters CR and LF are also recognized as new-
- lines. For example, if the newline convention is "any", a multiline
- mode circumflex matches before "xyz" in the string "abc\r\nxyz" rather
- than after CR, even though CR on its own is a valid newline. (It also
+ When the newline convention (see "Newline conventions" below) recog-
+ nizes the two-character sequence CRLF as a newline, this is preferred,
+ even if the single characters CR and LF are also recognized as new-
+ lines. For example, if the newline convention is "any", a multiline
+ mode circumflex matches before "xyz" in the string "abc\r\nxyz" rather
+ than after CR, even though CR on its own is a valid newline. (It also
matches at the very start of the string, of course.)
- Note that the sequences \A, \Z, and \z can be used to match the start
- and end of the subject in both modes, and if all branches of a pattern
- start with \A it is always anchored, whether or not PCRE2_MULTILINE is
+ Note that the sequences \A, \Z, and \z can be used to match the start
+ and end of the subject in both modes, and if all branches of a pattern
+ start with \A it is always anchored, whether or not PCRE2_MULTILINE is
set.
@@ -7139,73 +7125,73 @@
FULL STOP (PERIOD, DOT) AND \N
Outside a character class, a dot in the pattern matches any one charac-
- ter in the subject string except (by default) a character that signi-
+ ter in the subject string except (by default) a character that signi-
fies the end of a line.
- When a line ending is defined as a single character, dot never matches
- that character; when the two-character sequence CRLF is used, dot does
- not match CR if it is immediately followed by LF, but otherwise it
- matches all characters (including isolated CRs and LFs). When any Uni-
- code line endings are being recognized, dot does not match CR or LF or
+ When a line ending is defined as a single character, dot never matches
+ that character; when the two-character sequence CRLF is used, dot does
+ not match CR if it is immediately followed by LF, but otherwise it
+ matches all characters (including isolated CRs and LFs). When any Uni-
+ code line endings are being recognized, dot does not match CR or LF or
any of the other line ending characters.
- The behaviour of dot with regard to newlines can be changed. If the
- PCRE2_DOTALL option is set, a dot matches any one character, without
- exception. If the two-character sequence CRLF is present in the sub-
+ The behaviour of dot with regard to newlines can be changed. If the
+ PCRE2_DOTALL option is set, a dot matches any one character, without
+ exception. If the two-character sequence CRLF is present in the sub-
ject string, it takes two dots to match it.
- The handling of dot is entirely independent of the handling of circum-
- flex and dollar, the only relationship being that they both involve
+ The handling of dot is entirely independent of the handling of circum-
+ flex and dollar, the only relationship being that they both involve
newlines. Dot has no special meaning in a character class.
- The escape sequence \N when not followed by an opening brace behaves
- like a dot, except that it is not affected by the PCRE2_DOTALL option.
- In other words, it matches any character except one that signifies the
+ The escape sequence \N when not followed by an opening brace behaves
+ like a dot, except that it is not affected by the PCRE2_DOTALL option.
+ In other words, it matches any character except one that signifies the
end of a line.
When \N is followed by an opening brace it has a different meaning. See
- the section entitled "Non-printing characters" above for details. Perl
- also uses \N{name} to specify characters by Unicode name; PCRE2 does
+ the section entitled "Non-printing characters" above for details. Perl
+ also uses \N{name} to specify characters by Unicode name; PCRE2 does
not support this.
MATCHING A SINGLE CODE UNIT
- Outside a character class, the escape sequence \C matches any one code
- unit, whether or not a UTF mode is set. In the 8-bit library, one code
- unit is one byte; in the 16-bit library it is a 16-bit unit; in the
- 32-bit library it is a 32-bit unit. Unlike a dot, \C always matches
- line-ending characters. The feature is provided in Perl in order to
+ Outside a character class, the escape sequence \C matches any one code
+ unit, whether or not a UTF mode is set. In the 8-bit library, one code
+ unit is one byte; in the 16-bit library it is a 16-bit unit; in the
+ 32-bit library it is a 32-bit unit. Unlike a dot, \C always matches
+ line-ending characters. The feature is provided in Perl in order to
match individual bytes in UTF-8 mode, but it is unclear how it can use-
fully be used.
- Because \C breaks up characters into individual code units, matching
- one unit with \C in UTF-8 or UTF-16 mode means that the rest of the
- string may start with a malformed UTF character. This has undefined
- results, because PCRE2 assumes that it is matching character by charac-
- ter in a valid UTF string (by default it checks the subject string's
- validity at the start of processing unless the PCRE2_NO_UTF_CHECK or
+ Because \C breaks up characters into individual code units, matching
+ one unit with \C in UTF-8 or UTF-16 mode means that the rest of the
+ string may start with a malformed UTF character. This has undefined re-
+ sults, because PCRE2 assumes that it is matching character by character
+ in a valid UTF string (by default it checks the subject string's valid-
+ ity at the start of processing unless the PCRE2_NO_UTF_CHECK or
PCRE2_MATCH_INVALID_UTF option is used).
- An application can lock out the use of \C by setting the
- PCRE2_NEVER_BACKSLASH_C option when compiling a pattern. It is also
+ An application can lock out the use of \C by setting the
+ PCRE2_NEVER_BACKSLASH_C option when compiling a pattern. It is also
possible to build PCRE2 with the use of \C permanently disabled.
- PCRE2 does not allow \C to appear in lookbehind assertions (described
- below) in UTF-8 or UTF-16 modes, because this would make it impossible
- to calculate the length of the lookbehind. Neither the alternative
+ PCRE2 does not allow \C to appear in lookbehind assertions (described
+ below) in UTF-8 or UTF-16 modes, because this would make it impossible
+ to calculate the length of the lookbehind. Neither the alternative
matching function pcre2_dfa_match() nor the JIT optimizer support \C in
these UTF modes. The former gives a match-time error; the latter fails
to optimize and so the match is always run using the interpreter.
- In the 32-bit library, however, \C is always supported (when not
- explicitly locked out) because it always matches a single code unit,
+ In the 32-bit library, however, \C is always supported (when not ex-
+ plicitly locked out) because it always matches a single code unit,
whether or not UTF-32 is specified.
In general, the \C escape sequence is best avoided. However, one way of
- using it that avoids the problem of malformed UTF-8 or UTF-16 charac-
- ters is to use a lookahead to check the length of the next character,
- as in this pattern, which could be used with a UTF-8 string (ignore
+ using it that avoids the problem of malformed UTF-8 or UTF-16 charac-
+ ters is to use a lookahead to check the length of the next character,
+ as in this pattern, which could be used with a UTF-8 string (ignore
white space and line breaks):
(?| (?=[\x00-\x7f])(\C) |
@@ -7213,12 +7199,12 @@
(?=[\x{800}-\x{ffff}])(\C)(\C)(\C) |
(?=[\x{10000}-\x{1fffff}])(\C)(\C)(\C)(\C))
- In this example, a group that starts with (?| resets the capturing
- parentheses numbers in each alternative (see "Duplicate Group Numbers"
+ In this example, a group that starts with (?| resets the capturing
+ parentheses numbers in each alternative (see "Duplicate Group Numbers"
below). The assertions at the start of each branch check the next UTF-8
- character for values whose encoding uses 1, 2, 3, or 4 bytes, respec-
- tively. The character's individual bytes are then captured by the
- appropriate number of \C groups.
+ character for values whose encoding uses 1, 2, 3, or 4 bytes, respec-
+ tively. The character's individual bytes are then captured by the ap-
+ propriate number of \C groups.
SQUARE BRACKETS AND CHARACTER CLASSES
@@ -7225,62 +7211,61 @@
An opening square bracket introduces a character class, terminated by a
closing square bracket. A closing square bracket on its own is not spe-
- cial by default. If a closing square bracket is required as a member
+ cial by default. If a closing square bracket is required as a member
of the class, it should be the first data character in the class (after
- an initial circumflex, if present) or escaped with a backslash. This
- means that, by default, an empty class cannot be defined. However, if
- the PCRE2_ALLOW_EMPTY_CLASS option is set, a closing square bracket at
+ an initial circumflex, if present) or escaped with a backslash. This
+ means that, by default, an empty class cannot be defined. However, if
+ the PCRE2_ALLOW_EMPTY_CLASS option is set, a closing square bracket at
the start does end the (empty) class.
- A character class matches a single character in the subject. A matched
+ A character class matches a single character in the subject. A matched
character must be in the set of characters defined by the class, unless
- the first character in the class definition is a circumflex, in which
+ the first character in the class definition is a circumflex, in which
case the subject character must not be in the set defined by the class.
- If a circumflex is actually required as a member of the class, ensure
+ If a circumflex is actually required as a member of the class, ensure
it is not the first character, or escape it with a backslash.
- For example, the character class [aeiou] matches any lower case vowel,
- while [^aeiou] matches any character that is not a lower case vowel.
+ For example, the character class [aeiou] matches any lower case vowel,
+ while [^aeiou] matches any character that is not a lower case vowel.
Note that a circumflex is just a convenient notation for specifying the
- characters that are in the class by enumerating those that are not. A
- class that starts with a circumflex is not an assertion; it still con-
- sumes a character from the subject string, and therefore it fails if
+ characters that are in the class by enumerating those that are not. A
+ class that starts with a circumflex is not an assertion; it still con-
+ sumes a character from the subject string, and therefore it fails if
the current pointer is at the end of the string.
- Characters in a class may be specified by their code points using \o,
- \x, or \N{U+hh..} in the usual way. When caseless matching is set, any
- letters in a class represent both their upper case and lower case ver-
- sions, so for example, a caseless [aeiou] matches "A" as well as "a",
- and a caseless [^aeiou] does not match "A", whereas a caseful version
+ Characters in a class may be specified by their code points using \o,
+ \x, or \N{U+hh..} in the usual way. When caseless matching is set, any
+ letters in a class represent both their upper case and lower case ver-
+ sions, so for example, a caseless [aeiou] matches "A" as well as "a",
+ and a caseless [^aeiou] does not match "A", whereas a caseful version
would.
- Characters that might indicate line breaks are never treated in any
- special way when matching character classes, whatever line-ending
- sequence is in use, and whatever setting of the PCRE2_DOTALL and
- PCRE2_MULTILINE options is used. A class such as [^a] always matches
+ Characters that might indicate line breaks are never treated in any
+ special way when matching character classes, whatever line-ending se-
+ quence is in use, and whatever setting of the PCRE2_DOTALL and
+ PCRE2_MULTILINE options is used. A class such as [^a] always matches
one of these characters.
The generic character type escape sequences \d, \D, \h, \H, \p, \P, \s,
- \S, \v, \V, \w, and \W may appear in a character class, and add the
- characters that they match to the class. For example, [\dABCDEF]
- matches any hexadecimal digit. In UTF modes, the PCRE2_UCP option
- affects the meanings of \d, \s, \w and their upper case partners, just
- as it does when they appear outside a character class, as described in
- the section entitled "Generic character types" above. The escape
- sequence \b has a different meaning inside a character class; it
- matches the backspace character. The sequences \B, \R, and \X are not
- special inside a character class. Like any other unrecognized escape
- sequences, they cause an error. The same is true for \N when not fol-
- lowed by an opening brace.
+ \S, \v, \V, \w, and \W may appear in a character class, and add the
+ characters that they match to the class. For example, [\dABCDEF]
+ matches any hexadecimal digit. In UTF modes, the PCRE2_UCP option af-
+ fects the meanings of \d, \s, \w and their upper case partners, just as
+ it does when they appear outside a character class, as described in the
+ section entitled "Generic character types" above. The escape sequence
+ \b has a different meaning inside a character class; it matches the
+ backspace character. The sequences \B, \R, and \X are not special in-
+ side a character class. Like any other unrecognized escape sequences,
+ they cause an error. The same is true for \N when not followed by an
+ opening brace.
- The minus (hyphen) character can be used to specify a range of charac-
- ters in a character class. For example, [d-m] matches any letter
- between d and m, inclusive. If a minus character is required in a
- class, it must be escaped with a backslash or appear in a position
- where it cannot be interpreted as indicating a range, typically as the
- first or last character in the class, or immediately after a range. For
- example, [b-d-z] matches letters in the range b to d, a hyphen charac-
- ter, or z.
+ The minus (hyphen) character can be used to specify a range of charac-
+ ters in a character class. For example, [d-m] matches any letter be-
+ tween d and m, inclusive. If a minus character is required in a class,
+ it must be escaped with a backslash or appear in a position where it
+ cannot be interpreted as indicating a range, typically as the first or
+ last character in the class, or immediately after a range. For example,
+ [b-d-z] matches letters in the range b to d, a hyphen character, or z.
Perl treats a hyphen as a literal if it appears before or after a POSIX
class (see below) or before or after a character type escape such as as
@@ -7299,8 +7284,8 @@
a range.
Ranges normally include all code points between the start and end char-
- acters, inclusive. They can also be used for code points specified
- numerically, for example [\000-\037]. Ranges can include any characters
+ acters, inclusive. They can also be used for code points specified nu-
+ merically, for example [\000-\037]. Ranges can include any characters
that are valid for the current mode. In any UTF mode, the so-called
"surrogate" characters (those whose code points lie between 0xd800 and
0xdfff inclusive) may not be specified explicitly by default (the
@@ -7334,8 +7319,8 @@
range), circumflex (only at the start), opening square bracket (only
when it can be interpreted as introducing a POSIX class name, or for a
special compatibility feature - see the next two sections), and the
- terminating closing square bracket. However, escaping other non-
- alphanumeric characters does no harm.
+ terminating closing square bracket. However, escaping other non-al-
+ phanumeric characters does no harm.
POSIX CHARACTER CLASSES
@@ -7384,8 +7369,8 @@
ters in the range 128-255 when locale-specific matching is happening.
However, if the PCRE2_UCP option is passed to pcre2_compile(), some of
the classes are changed so that Unicode character properties are used.
- This is achieved by replacing certain POSIX classes with other
- sequences, as follows:
+ This is achieved by replacing certain POSIX classes with other se-
+ quences, as follows:
[:alnum:] becomes \p{Xan}
[:alpha:] becomes \p{L}
@@ -7436,9 +7421,9 @@
from other environments, and is best not used in any new patterns. Note
that \b matches at the start and the end of a word (see "Simple asser-
tions" above), and in a Perl-style pattern the preceding or following
- character normally shows which is wanted, without the need for the
- assertions that are used above in order to give exactly the POSIX be-
- haviour.
+ character normally shows which is wanted, without the need for the as-
+ sertions that are used above in order to give exactly the POSIX behav-
+ iour.
VERTICAL BAR
@@ -7460,8 +7445,8 @@
The settings of the PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL,
PCRE2_EXTENDED, PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE options
- can be changed from within the pattern by a sequence of letters
- enclosed between "(?" and ")". These options are Perl-compatible, and
+ can be changed from within the pattern by a sequence of letters en-
+ closed between "(?" and ")". These options are Perl-compatible, and
are described in detail in the pcre2api documentation. The option let-
ters are:
@@ -7473,8 +7458,8 @@
xx for PCRE2_EXTENDED_MORE
For example, (?im) sets caseless, multiline matching. It is also possi-
- ble to unset these options by preceding the relevant letters with a
- hyphen, for example (?-im). The two "extended" options are not indepen-
+ ble to unset these options by preceding the relevant letters with a hy-
+ phen, for example (?-im). The two "extended" options are not indepen-
dent; unsetting either one cancels the effects of both of them.
A combined setting and unsetting such as (?im-sx), which sets
@@ -7486,15 +7471,15 @@
If the first character following (? is a circumflex, it causes all of
the above options to be unset. Thus, (?^) is equivalent to (?-imnsx).
- Letters may follow the circumflex to cause some options to be re-
- instated, but a hyphen may not appear.
+ Letters may follow the circumflex to cause some options to be re-in-
+ stated, but a hyphen may not appear.
The PCRE2-specific options PCRE2_DUPNAMES and PCRE2_UNGREEDY can be
changed in the same way as the Perl-compatible options by using the
characters J and U respectively. However, these are not unset by (?^).
- When one of these option changes occurs at top level (that is, not
- inside group parentheses), the change applies to the remainder of the
+ When one of these option changes occurs at top level (that is, not in-
+ side group parentheses), the change applies to the remainder of the
pattern that follows. An option change within a group (see below for a
description of groups) affects only that part of the group that follows
it, so
@@ -7667,11 +7652,11 @@
well as convenience functions for extracting captured substrings by
name.
- Warning: When more than one capture group has the same number, as
- described in the previous section, a name given to one of them applies
- to all of them. Perl allows identically numbered groups to have differ-
- ent names. Consider this pattern, where there are two capture groups,
- both numbered 1:
+ Warning: When more than one capture group has the same number, as de-
+ scribed in the previous section, a name given to one of them applies to
+ all of them. Perl allows identically numbered groups to have different
+ names. Consider this pattern, where there are two capture groups, both
+ numbered 1:
(?|(?<AA>aa)|(?<BB>bb))
@@ -7733,8 +7718,8 @@
conditions below), either to check whether a capture group has matched,
or to check for recursion, all groups with the same name are tested. If
the condition is true for any one of them, the overall condition is
- true. This is the same behaviour as testing by number. For further
- details of the interfaces for handling named capture groups, see the
+ true. This is the same behaviour as testing by number. For further de-
+ tails of the interfaces for handling named capture groups, see the
pcre2api documentation.
@@ -7817,10 +7802,10 @@
By default, quantifiers are "greedy", that is, they match as much as
possible (up to the maximum number of permitted times), without causing
the rest of the pattern to fail. The classic example of where this
- gives problems is in trying to match comments in C programs. These
- appear between /* and */ and within the comment, individual * and /
- characters may appear. An attempt to match C comments by applying the
- pattern
+ gives problems is in trying to match comments in C programs. These ap-
+ pear between /* and */ and within the comment, individual * and / char-
+ acters may appear. An attempt to match C comments by applying the pat-
+ tern
/\*.*\*/
@@ -7852,16 +7837,16 @@
words, it inverts the default behaviour.
When a parenthesized group is quantified with a minimum repeat count
- that is greater than 1 or with a limited maximum, more memory is
- required for the compiled pattern, in proportion to the size of the
- minimum or maximum.
+ that is greater than 1 or with a limited maximum, more memory is re-
+ quired for the compiled pattern, in proportion to the size of the mini-
+ mum or maximum.
If a pattern starts with .* or .{0,} and the PCRE2_DOTALL option
(equivalent to Perl's /s) is set, thus allowing the dot to match new-
lines, the pattern is implicitly anchored, because whatever follows
will be tried against every character position in the subject string,
- so there is no point in retrying the overall match at any position
- after the first. PCRE2 normally treats such a pattern as though it were
+ so there is no point in retrying the overall match at any position af-
+ ter the first. PCRE2 normally treats such a pattern as though it were
preceded by \A.
In cases where it is known that the subject string contains no new-
@@ -7946,8 +7931,8 @@
match, if anchored at the current point in the subject string.
Atomic groups are not capture groups. Simple cases such as the above
- example can be thought of as a maximizing repeat that must swallow
- everything it can. So, while both \d+ and \d+? are prepared to adjust
+ example can be thought of as a maximizing repeat that must swallow ev-
+ erything it can. So, while both \d+ and \d+? are prepared to adjust
the number of digits they match in order to make the rest of the pat-
tern match, (?>\d+) can only match an entire sequence of digits.
@@ -7965,10 +7950,10 @@
(abc|xyz){2,3}+
- Possessive quantifiers are always greedy; the setting of the
- PCRE2_UNGREEDY option is ignored. They are a convenient notation for
- the simpler forms of atomic group. However, there is no difference in
- the meaning of a possessive quantifier and the equivalent atomic group,
+ Possessive quantifiers are always greedy; the setting of the PCRE2_UN-
+ GREEDY option is ignored. They are a convenient notation for the sim-
+ pler forms of atomic group. However, there is no difference in the
+ meaning of a possessive quantifier and the equivalent atomic group,
though there may be a performance difference; possessive quantifiers
should be slightly faster.
@@ -7984,8 +7969,8 @@
when B must follow. This feature can be disabled by the PCRE2_NO_AUTO-
POSSESS option, or starting the pattern with (*NO_AUTO_POSSESS).
- When a pattern contains an unlimited repeat inside a group that can
- itself be repeated an unlimited number of times, the use of an atomic
+ When a pattern contains an unlimited repeat inside a group that can it-
+ self be repeated an unlimited number of times, the use of an atomic
group is the only way to avoid some failing matches taking a very long
time indeed. The pattern
@@ -7999,13 +7984,13 @@
it takes a long time before reporting failure. This is because the
string can be divided between the internal \D+ repeat and the external
- * repeat in a large number of ways, and all have to be tried. (The
- example uses [!?] rather than a single character at the end, because
- both PCRE2 and Perl have an optimization that allows for fast failure
- when a single character is used. They remember the last single charac-
- ter that is required for a match, and fail early if it is not present
- in the string.) If the pattern is changed so that it uses an atomic
- group, like this:
+ * repeat in a large number of ways, and all have to be tried. (The ex-
+ ample uses [!?] rather than a single character at the end, because both
+ PCRE2 and Perl have an optimization that allows for fast failure when a
+ single character is used. They remember the last single character that
+ is required for a match, and fail early if it is not present in the
+ string.) If the pattern is changed so that it uses an atomic group,
+ like this:
((?>\D+)|<\d+>)*[!?]
@@ -8115,8 +8100,8 @@
A backreference that occurs inside the group to which it refers fails
when the group is first used, so, for example, (a\1) never matches.
- However, such references can be useful inside repeated groups. For
- example, the pattern
+ However, such references can be useful inside repeated groups. For ex-
+ ample, the pattern
(a|b\1)+
@@ -8142,8 +8127,8 @@
More complicated assertions are coded as parenthesized groups. There
are two kinds: those that look ahead of the current position in the
- subject string, and those that look behind it, and in each case an
- assertion may be positive (must match for the assertion to be true) or
+ subject string, and those that look behind it, and in each case an as-
+ sertion may be positive (must match for the assertion to be true) or
negative (must not match for the assertion to be true). An assertion
group is matched in the normal way, and if it is true, matching contin-
ues after it, but with the matching position in the subject string is
@@ -8150,8 +8135,8 @@
was it was before the assertion was processed.
A lookaround assertion may also appear as the condition in a condi-
- tional group (see below). In this case, the result of matching the
- assertion determines which branch of the condition is followed.
+ tional group (see below). In this case, the result of matching the as-
+ sertion determines which branch of the condition is followed.
Lookaround assertions are atomic. If an assertion is true, but there is
a subsequent matching failure, there is no backtracking into the asser-
@@ -8159,8 +8144,8 @@
Assertion groups are not capture groups. If an assertion contains cap-
ture groups within it, these are counted for the purposes of numbering
- the capture groups in the whole pattern. Within each branch of an
- assertion, locally captured substrings may be referenced in the usual
+ the capture groups in the whole pattern. Within each branch of an as-
+ sertion, locally captured substrings may be referenced in the usual
way. For example, a sequence such as (.)\g{-1} can be used to check
that two adjacent characters are the same.
@@ -8240,8 +8225,8 @@
"bar". A lookbehind assertion is needed to achieve the other effect.
If you want to force a matching failure at some point in a pattern, the
- most convenient way to do it is with (?!) because an empty string
- always matches, so an assertion that requires there not to be an empty
+ most convenient way to do it is with (?!) because an empty string al-
+ ways matches, so an assertion that requires there not to be an empty
string must always fail. The backtracking control verb (*FAIL) or (*F)
is a synonym for (?!).
@@ -8297,18 +8282,18 @@
that is already active, is not supported.
Perl does not support backreferences in lookbehinds. PCRE2 does support
- them, but only if certain conditions are met. The
- PCRE2_MATCH_UNSET_BACKREF option must not be set, there must be no use
- of (?| in the pattern (it creates duplicate group numbers), and if the
- backreference is by name, the name must be unique. Of course, the ref-
- erenced group must itself match a fixed length substring. The following
- pattern matches words containing at least two characters that begin and
- end with the same character:
+ them, but only if certain conditions are met. The PCRE2_MATCH_UN-
+ SET_BACKREF option must not be set, there must be no use of (?| in the
+ pattern (it creates duplicate group numbers), and if the backreference
+ is by name, the name must be unique. Of course, the referenced group
+ must itself match a fixed length substring. The following pattern
+ matches words containing at least two characters that begin and end
+ with the same character:
\b(\w)\w++(?<=\1)
- Possessive quantifiers can be used in conjunction with lookbehind
- assertions to specify efficient matching of fixed-length strings at the
+ Possessive quantifiers can be used in conjunction with lookbehind as-
+ sertions to specify efficient matching of fixed-length strings at the
end of subject strings. Consider a simple pattern such as
abcd$
@@ -8379,9 +8364,9 @@
If part of a pattern is enclosed between (*script_run: or (*sr: and a
closing parenthesis, it fails if the sequence of characters that it
- matches are not a script run. After a failure, normal backtracking
- occurs. Script runs can be used to detect spoofing attacks using char-
- acters that look the same, but are from different scripts. The string
+ matches are not a script run. After a failure, normal backtracking oc-
+ curs. Script runs can be used to detect spoofing attacks using charac-
+ ters that look the same, but are from different scripts. The string
"paypal.com" is an infamous example, where the letters could be a mix-
ture of Latin and Cyrillic. This pattern ensures that the matched char-
acters in a sequence of non-spaces that follow white space are a script
@@ -8437,9 +8422,9 @@
If the condition is satisfied, the yes-pattern is used; otherwise the
no-pattern (if present) is used. An absent no-pattern is equivalent to
an empty string (it always matches). If there are more than two alter-
- natives in the group, a compile-time error occurs. Each of the two
- alternatives may itself contain nested groups of any form, including
- conditional groups; the restriction to two alternatives applies only at
+ natives in the group, a compile-time error occurs. Each of the two al-
+ ternatives may itself contain nested groups of any form, including con-
+ ditional groups; the restriction to two alternatives applies only at
the level of the condition itself. This pattern fragment is an example
where the alternatives are complex:
@@ -8546,65 +8531,64 @@
If the condition is the string (DEFINE), the condition is always false,
even if there is a group with the name DEFINE. In this case, there may
- be only one alternative in the rest of the conditional group. It is
- always skipped if control reaches this point in the pattern; the idea
- of DEFINE is that it can be used to define subroutines that can be ref-
- erenced from elsewhere. (The use of subroutines is described below.)
- For example, a pattern to match an IPv4 address such as
- "192.168.23.245" could be written like this (ignore white space and
- line breaks):
+ be only one alternative in the rest of the conditional group. It is al-
+ ways skipped if control reaches this point in the pattern; the idea of
+ DEFINE is that it can be used to define subroutines that can be refer-
+ enced from elsewhere. (The use of subroutines is described below.) For
+ example, a pattern to match an IPv4 address such as "192.168.23.245"
+ could be written like this (ignore white space and line breaks):
(?(DEFINE) (?<byte> 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d) )
\b (?&byte) (\.(?&byte)){3} \b
- The first part of the pattern is a DEFINE group inside which a another
- group named "byte" is defined. This matches an individual component of
- an IPv4 address (a number less than 256). When matching takes place,
- this part of the pattern is skipped because DEFINE acts like a false
- condition. The rest of the pattern uses references to the named group
- to match the four dot-separated components of an IPv4 address, insist-
+ The first part of the pattern is a DEFINE group inside which a another
+ group named "byte" is defined. This matches an individual component of
+ an IPv4 address (a number less than 256). When matching takes place,
+ this part of the pattern is skipped because DEFINE acts like a false
+ condition. The rest of the pattern uses references to the named group
+ to match the four dot-separated components of an IPv4 address, insist-
ing on a word boundary at each end.
Checking the PCRE2 version
- Programs that link with a PCRE2 library can check the version by call-
- ing pcre2_config() with appropriate arguments. Users of applications
- that do not have access to the underlying code cannot do this. A spe-
- cial "condition" called VERSION exists to allow such users to discover
+ Programs that link with a PCRE2 library can check the version by call-
+ ing pcre2_config() with appropriate arguments. Users of applications
+ that do not have access to the underlying code cannot do this. A spe-
+ cial "condition" called VERSION exists to allow such users to discover
which version of PCRE2 they are dealing with by using this condition to
- match a string such as "yesno". VERSION must be followed either by "="
+ match a string such as "yesno". VERSION must be followed either by "="
or ">=" and a version number. For example:
(?(VERSION>=10.4)yes|no)
- This pattern matches "yes" if the PCRE2 version is greater or equal to
- 10.4, or "no" otherwise. The fractional part of the version number may
+ This pattern matches "yes" if the PCRE2 version is greater or equal to
+ 10.4, or "no" otherwise. The fractional part of the version number may
not contain more than two digits.
Assertion conditions
- If the condition is not in any of the above formats, it must be a
- parenthesized assertion. This may be a positive or negative lookahead
- or lookbehind assertion. Consider this pattern, again containing non-
- significant white space, and with the two alternatives on the second
+ If the condition is not in any of the above formats, it must be a
+ parenthesized assertion. This may be a positive or negative lookahead
+ or lookbehind assertion. Consider this pattern, again containing non-
+ significant white space, and with the two alternatives on the second
line:
(?(?=[^a-z]*[a-z])
\d{2}-[a-z]{3}-\d{2} | \d{2}-\d{2}-\d{2} )
- The condition is a positive lookahead assertion that matches an
- optional sequence of non-letters followed by a letter. In other words,
- it tests for the presence of at least one letter in the subject. If a
- letter is found, the subject is matched against the first alternative;
- otherwise it is matched against the second. This pattern matches
- strings in one of the two forms dd-aaa-dd or dd-dd-dd, where aaa are
+ The condition is a positive lookahead assertion that matches an op-
+ tional sequence of non-letters followed by a letter. In other words, it
+ tests for the presence of at least one letter in the subject. If a let-
+ ter is found, the subject is matched against the first alternative;
+ otherwise it is matched against the second. This pattern matches
+ strings in one of the two forms dd-aaa-dd or dd-dd-dd, where aaa are
letters and dd are digits.
When an assertion that is a condition contains capture groups, any cap-
- turing that occurs in a matching branch is retained afterwards, for
- both positive and negative assertions, because matching always contin-
- ues after the assertion, whether it succeeds or fails. (Compare non-
- conditional assertions, for which captures are retained only for posi-
+ turing that occurs in a matching branch is retained afterwards, for
+ both positive and negative assertions, because matching always contin-
+ ues after the assertion, whether it succeeds or fails. (Compare non-
+ conditional assertions, for which captures are retained only for posi-
tive assertions that succeed.)
@@ -8611,44 +8595,44 @@
COMMENTS
There are two ways of including comments in patterns that are processed
- by PCRE2. In both cases, the start of the comment must not be in a
- character class, nor in the middle of any other sequence of related
- characters such as (?: or a group name or number. The characters that
+ by PCRE2. In both cases, the start of the comment must not be in a
+ character class, nor in the middle of any other sequence of related
+ characters such as (?: or a group name or number. The characters that
make up a comment play no part in the pattern matching.
- The sequence (?# marks the start of a comment that continues up to the
- next closing parenthesis. Nested parentheses are not permitted. If the
- PCRE2_EXTENDED or PCRE2_EXTENDED_MORE option is set, an unescaped #
- character also introduces a comment, which in this case continues to
- immediately after the next newline character or character sequence in
+ The sequence (?# marks the start of a comment that continues up to the
+ next closing parenthesis. Nested parentheses are not permitted. If the
+ PCRE2_EXTENDED or PCRE2_EXTENDED_MORE option is set, an unescaped #
+ character also introduces a comment, which in this case continues to
+ immediately after the next newline character or character sequence in
the pattern. Which characters are interpreted as newlines is controlled
- by an option passed to the compiling function or by a special sequence
+ by an option passed to the compiling function or by a special sequence
at the start of the pattern, as described in the section entitled "New-
line conventions" above. Note that the end of this type of comment is a
- literal newline sequence in the pattern; escape sequences that happen
+ literal newline sequence in the pattern; escape sequences that happen
to represent a newline do not count. For example, consider this pattern
- when PCRE2_EXTENDED is set, and the default newline convention (a sin-
+ when PCRE2_EXTENDED is set, and the default newline convention (a sin-
gle linefeed character) is in force:
abc #comment \n still comment
- On encountering the # character, pcre2_compile() skips along, looking
- for a newline in the pattern. The sequence \n is still literal at this
- stage, so it does not terminate the comment. Only an actual character
+ On encountering the # character, pcre2_compile() skips along, looking
+ for a newline in the pattern. The sequence \n is still literal at this
+ stage, so it does not terminate the comment. Only an actual character
with the code value 0x0a (the default newline) does so.
RECURSIVE PATTERNS
- Consider the problem of matching a string in parentheses, allowing for
- unlimited nested parentheses. Without the use of recursion, the best
- that can be done is to use a pattern that matches up to some fixed
- depth of nesting. It is not possible to handle an arbitrary nesting
+ Consider the problem of matching a string in parentheses, allowing for
+ unlimited nested parentheses. Without the use of recursion, the best
+ that can be done is to use a pattern that matches up to some fixed
+ depth of nesting. It is not possible to handle an arbitrary nesting
depth.
For some time, Perl has provided a facility that allows regular expres-
- sions to recurse (amongst other things). It does this by interpolating
- Perl code in the expression at run time, and the code can refer to the
+ sions to recurse (amongst other things). It does this by interpolating
+ Perl code in the expression at run time, and the code can refer to the
expression itself. A Perl pattern using code interpolation to solve the
parentheses problem can be created like this:
@@ -8657,67 +8641,67 @@
The (?p{...}) item interpolates Perl code at run time, and in this case
refers recursively to the pattern in which it appears.
- Obviously, PCRE2 cannot support the interpolation of Perl code.
- Instead, it supports special syntax for recursion of the entire pat-
- tern, and also for individual capture group recursion. After its intro-
- duction in PCRE1 and Python, this kind of recursion was subsequently
- introduced into Perl at release 5.10.
+ Obviously, PCRE2 cannot support the interpolation of Perl code. In-
+ stead, it supports special syntax for recursion of the entire pattern,
+ and also for individual capture group recursion. After its introduction
+ in PCRE1 and Python, this kind of recursion was subsequently introduced
+ into Perl at release 5.10.
- A special item that consists of (? followed by a number greater than
- zero and a closing parenthesis is a recursive subroutine call of the
- capture group of the given number, provided that it occurs inside that
- group. (If not, it is a non-recursive subroutine call, which is
- described in the next section.) The special item (?R) or (?0) is a
- recursive call of the entire regular expression.
+ A special item that consists of (? followed by a number greater than
+ zero and a closing parenthesis is a recursive subroutine call of the
+ capture group of the given number, provided that it occurs inside that
+ group. (If not, it is a non-recursive subroutine call, which is de-
+ scribed in the next section.) The special item (?R) or (?0) is a recur-
+ sive call of the entire regular expression.
- This PCRE2 pattern solves the nested parentheses problem (assume the
+ This PCRE2 pattern solves the nested parentheses problem (assume the
PCRE2_EXTENDED option is set so that white space is ignored):
\( ( [^()]++ | (?R) )* \)
- First it matches an opening parenthesis. Then it matches any number of
- substrings which can either be a sequence of non-parentheses, or a
- recursive match of the pattern itself (that is, a correctly parenthe-
- sized substring). Finally there is a closing parenthesis. Note the use
- of a possessive quantifier to avoid backtracking into sequences of non-
+ First it matches an opening parenthesis. Then it matches any number of
+ substrings which can either be a sequence of non-parentheses, or a re-
+ cursive match of the pattern itself (that is, a correctly parenthesized
+ substring). Finally there is a closing parenthesis. Note the use of a
+ possessive quantifier to avoid backtracking into sequences of non-
parentheses.
- If this were part of a larger pattern, you would not want to recurse
+ If this were part of a larger pattern, you would not want to recurse
the entire pattern, so instead you could use this:
( \( ( [^()]++ | (?1) )* \) )
- We have put the pattern into parentheses, and caused the recursion to
+ We have put the pattern into parentheses, and caused the recursion to
refer to them instead of the whole pattern.
- In a larger pattern, keeping track of parenthesis numbers can be
- tricky. This is made easier by the use of relative references. Instead
+ In a larger pattern, keeping track of parenthesis numbers can be
+ tricky. This is made easier by the use of relative references. Instead
of (?1) in the pattern above you can write (?-2) to refer to the second
- most recently opened parentheses preceding the recursion. In other
- words, a negative number counts capturing parentheses leftwards from
+ most recently opened parentheses preceding the recursion. In other
+ words, a negative number counts capturing parentheses leftwards from
the point at which it is encountered.
- Be aware however, that if duplicate capture group numbers are in use,
- relative references refer to the earliest group with the appropriate
+ Be aware however, that if duplicate capture group numbers are in use,
+ relative references refer to the earliest group with the appropriate
number. Consider, for example:
(?|(a)|(b)) (c) (?-2)
The first two capture groups (a) and (b) are both numbered 1, and group
- (c) is number 2. When the reference (?-2) is encountered, the second
- most recently opened parentheses has the number 1, but it is the first
+ (c) is number 2. When the reference (?-2) is encountered, the second
+ most recently opened parentheses has the number 1, but it is the first
such group (the (a) group) to which the recursion refers. This would be
- the same if an absolute reference (?1) was used. In other words, rela-
+ the same if an absolute reference (?1) was used. In other words, rela-
tive references are just a shorthand for computing a group number.
- It is also possible to refer to subsequent capture groups, by writing
- references such as (?+2). However, these cannot be recursive because
- the reference is not inside the parentheses that are referenced. They
- are always non-recursive subroutine calls, as described in the next
+ It is also possible to refer to subsequent capture groups, by writing
+ references such as (?+2). However, these cannot be recursive because
+ the reference is not inside the parentheses that are referenced. They
+ are always non-recursive subroutine calls, as described in the next
section.
- An alternative approach is to use named parentheses. The Perl syntax
- for this is (?&name); PCRE1's earlier syntax (?P>name) is also sup-
+ An alternative approach is to use named parentheses. The Perl syntax
+ for this is (?&name); PCRE1's earlier syntax (?P>name) is also sup-
ported. We could rewrite the above example as follows:
(?<pn> \( ( [^()]++ | (?&pn) )* \) )
@@ -8726,40 +8710,40 @@
used.
The example pattern that we have been looking at contains nested unlim-
- ited repeats, and so the use of a possessive quantifier for matching
- strings of non-parentheses is important when applying the pattern to
+ ited repeats, and so the use of a possessive quantifier for matching
+ strings of non-parentheses is important when applying the pattern to
strings that do not match. For example, when this pattern is applied to
(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa()
- it yields "no match" quickly. However, if a possessive quantifier is
- not used, the match runs for a very long time indeed because there are
- so many different ways the + and * repeats can carve up the subject,
+ it yields "no match" quickly. However, if a possessive quantifier is
+ not used, the match runs for a very long time indeed because there are
+ so many different ways the + and * repeats can carve up the subject,
and all have to be tested before failure can be reported.
- At the end of a match, the values of capturing parentheses are those
- from the outermost level. If you want to obtain intermediate values, a
+ At the end of a match, the values of capturing parentheses are those
+ from the outermost level. If you want to obtain intermediate values, a
callout function can be used (see below and the pcre2callout documenta-
tion). If the pattern above is matched against
(ab(cd)ef)
- the value for the inner capturing parentheses (numbered 2) is "ef",
- which is the last value taken on at the top level. If a capture group
- is not matched at the top level, its final captured value is unset,
- even if it was (temporarily) set at a deeper level during the matching
+ the value for the inner capturing parentheses (numbered 2) is "ef",
+ which is the last value taken on at the top level. If a capture group
+ is not matched at the top level, its final captured value is unset,
+ even if it was (temporarily) set at a deeper level during the matching
process.
- Do not confuse the (?R) item with the condition (R), which tests for
- recursion. Consider this pattern, which matches text in angle brack-
- ets, allowing for arbitrary nesting. Only digits are allowed in nested
- brackets (that is, when recursing), whereas any characters are permit-
+ Do not confuse the (?R) item with the condition (R), which tests for
+ recursion. Consider this pattern, which matches text in angle brack-
+ ets, allowing for arbitrary nesting. Only digits are allowed in nested
+ brackets (that is, when recursing), whereas any characters are permit-
ted at the outer level.
< (?: (?(R) \d++ | [^<>]*+) | (?R)) * >
- In this pattern, (?(R) is the start of a conditional group, with two
- different alternatives for the recursive and non-recursive cases. The
+ In this pattern, (?(R) is the start of a conditional group, with two
+ different alternatives for the recursive and non-recursive cases. The
(?R) item is the actual recursive call.
Differences in recursion processing between PCRE2 and Perl
@@ -8766,22 +8750,21 @@
Some former differences between PCRE2 and Perl no longer exist.
- Before release 10.30, recursion processing in PCRE2 differed from Perl
- in that a recursive subroutine call was always treated as an atomic
- group. That is, once it had matched some of the subject string, it was
- never re-entered, even if it contained untried alternatives and there
- was a subsequent matching failure. (Historical note: PCRE implemented
+ Before release 10.30, recursion processing in PCRE2 differed from Perl
+ in that a recursive subroutine call was always treated as an atomic
+ group. That is, once it had matched some of the subject string, it was
+ never re-entered, even if it contained untried alternatives and there
+ was a subsequent matching failure. (Historical note: PCRE implemented
recursion before Perl did.)
- Starting with release 10.30, recursive subroutine calls are no longer
+ Starting with release 10.30, recursive subroutine calls are no longer
treated as atomic. That is, they can be re-entered to try unused alter-
- natives if there is a matching failure later in the pattern. This is
- now compatible with the way Perl works. If you want a subroutine call
+ natives if there is a matching failure later in the pattern. This is
+ now compatible with the way Perl works. If you want a subroutine call
to be atomic, you must explicitly enclose it in an atomic group.
- Supporting backtracking into recursions simplifies certain types of
- recursive pattern. For example, this pattern matches palindromic
- strings:
+ Supporting backtracking into recursions simplifies certain types of re-
+ cursive pattern. For example, this pattern matches palindromic strings:
^((.)(?1)\2|.?)$
@@ -8824,9 +8807,9 @@
is used outside the parentheses to which it refers, it operates a bit
like a subroutine in a programming language. More accurately, PCRE2
treats the referenced group as an independent subpattern which it tries
- to match at the current matching position. The called group may be
- defined before or after the reference. A numbered reference can be
- absolute or relative, as in these examples:
+ to match at the current matching position. The called group may be de-
+ fined before or after the reference. A numbered reference can be abso-
+ lute or relative, as in these examples:
(...(absolute)...)...(?2)...
(...(relative)...)...(?-1)...
@@ -8868,8 +8851,8 @@
For compatibility with Oniguruma, the non-Perl syntax \g followed by a
name or a number enclosed either in angle brackets or single quotes, is
- an alternative syntax for calling a group as a subroutine, possibly
- recursively. Here are two of the examples used above, rewritten using
+ an alternative syntax for calling a group as a subroutine, possibly re-
+ cursively. Here are two of the examples used above, rewritten using
this syntax:
(?<pn> \( ( (?>[^()]+) | \g<pn> )* \) )
@@ -9049,12 +9032,12 @@
where A, B, and C may be complex expressions. After matching "A", the
matcher processes "BC"; if that fails, causing a backtrack, (*ACCEPT)
is triggered and the match succeeds. In both cases, all but C is cap-
- tured. Whereas (*COMMIT) (see below) means "fail on backtrack", a
- repeated (*ACCEPT) of this type means "succeed on backtrack".
+ tured. Whereas (*COMMIT) (see below) means "fail on backtrack", a re-
+ peated (*ACCEPT) of this type means "succeed on backtrack".
- Warning: (*ACCEPT) should not be used within a script run group,
- because it causes an immediate exit from the group, bypassing the
- script run checking.
+ Warning: (*ACCEPT) should not be used within a script run group, be-
+ cause it causes an immediate exit from the group, bypassing the script
+ run checking.
(*FAIL) or (*FAIL:NAME)
@@ -9070,15 +9053,15 @@
A match with the string "aaaa" always fails, but the callout is taken
before each backtrack happens (in this example, 10 times).
- (*ACCEPT:NAME) and (*FAIL:NAME) behave the same as
- (*MARK:NAME)(*ACCEPT) and (*MARK:NAME)(*FAIL), respectively, that is, a
- (*MARK) is recorded just before the verb acts.
+ (*ACCEPT:NAME) and (*FAIL:NAME) behave the same as (*MARK:NAME)(*AC-
+ CEPT) and (*MARK:NAME)(*FAIL), respectively, that is, a (*MARK) is
+ recorded just before the verb acts.
Recording which path was taken
- There is one verb whose main purpose is to track how a match was
- arrived at, though it also has a secondary use in conjunction with
- advancing the match starting point (see (*SKIP) below).
+ There is one verb whose main purpose is to track how a match was ar-
+ rived at, though it also has a secondary use in conjunction with ad-
+ vancing the match starting point (see (*SKIP) below).
(*MARK:NAME) or (*:NAME)
@@ -9175,8 +9158,8 @@
(*COMMIT) during a match does not always guarantee that a match must be
at this starting point.
- Note that (*COMMIT) at the start of a pattern is not the same as an
- anchor, unless PCRE2's start-of-match optimizations are turned off, as
+ Note that (*COMMIT) at the start of a pattern is not the same as an an-
+ chor, unless PCRE2's start-of-match optimizations are turned off, as
shown in this output from pcre2test:
re> /(*COMMIT)abc/
@@ -9229,14 +9212,14 @@
(starting at the first character in the string), the starting point
skips on to start the next attempt at "c". Note that a possessive quan-
tifer does not have the same effect as this example; although it would
- suppress backtracking during the first match attempt, the second
- attempt would start at the second character instead of skipping on to
+ suppress backtracking during the first match attempt, the second at-
+ tempt would start at the second character instead of skipping on to
"c".
- If (*SKIP) is used inside a lookbehind to specify a new starting posi-
- tion that is not later than the starting point of the current match,
- the position specified by (*SKIP) is ignored, and instead the normal
- "bumpalong" occurs.
+ If (*SKIP) is used to specify a new starting position that is the same
+ as the starting position of the current match, or (by being inside a
+ lookbehind) earlier, the position specified by (*SKIP) is ignored, and
+ instead the normal "bumpalong" occurs.
(*SKIP:NAME)
@@ -9289,8 +9272,8 @@
skips to the second alternative and tries COND2, without backtracking
into COND1. If that succeeds and BAR fails, COND3 is tried. If subse-
quently BAZ fails, there are no more alternatives, so there is a back-
- track to whatever came before the entire group. If (*THEN) is not
- inside an alternation, it acts like (*PRUNE).
+ track to whatever came before the entire group. If (*THEN) is not in-
+ side an alternation, it acts like (*PRUNE).
The behaviour of (*THEN:NAME) is not the same as (*MARK:NAME)(*THEN).
It is like (*MARK:NAME) in that the name is remembered for passing back
@@ -9297,11 +9280,11 @@
to the caller. However, (*SKIP:NAME) searches only for names set with
(*MARK), ignoring those set by other backtracking verbs.
- A group that does not contain a | character is just a part of the
- enclosing alternative; it is not a nested alternation with only one
- alternative. The effect of (*THEN) extends beyond such a group to the
- enclosing alternative. Consider this pattern, where A, B, etc. are
- complex pattern fragments that do not contain any | characters at this
+ A group that does not contain a | character is just a part of the en-
+ closing alternative; it is not a nested alternation with only one al-
+ ternative. The effect of (*THEN) extends beyond such a group to the en-
+ closing alternative. Consider this pattern, where A, B, etc. are com-
+ plex pattern fragments that do not contain any | characters at this
level:
A (B(*THEN)C) | D
@@ -9325,14 +9308,14 @@
^.*? (?(?=a) a | b(*THEN)c )
- If the subject is "ba", this pattern does not match. Because .*? is
- ungreedy, it initially matches zero characters. The condition (?=a)
- then fails, the character "b" is matched, but "c" is not. At this
- point, matching does not backtrack to .*? as might perhaps be expected
- from the presence of the | character. The conditional group is part of
- the single alternative that comprises the whole pattern, and so the
- match fails. (If there was a backtrack into .*?, allowing it to match
- "b", the match would succeed.)
+ If the subject is "ba", this pattern does not match. Because .*? is un-
+ greedy, it initially matches zero characters. The condition (?=a) then
+ fails, the character "b" is matched, but "c" is not. At this point,
+ matching does not backtrack to .*? as might perhaps be expected from
+ the presence of the | character. The conditional group is part of the
+ single alternative that comprises the whole pattern, and so the match
+ fails. (If there was a backtrack into .*?, allowing it to match "b",
+ the match would succeed.)
The verbs just described provide four different "strengths" of control
when subsequent matching fails. (*THEN) is the weakest, carrying on the
@@ -9383,9 +9366,9 @@
(*ACCEPT) in a standalone positive assertion causes the assertion to
succeed without any further processing; captured strings and a mark
- name (if set) are retained. In a standalone negative assertion,
- (*ACCEPT) causes the assertion to fail without any further processing;
- captured substrings and any mark name are discarded.
+ name (if set) are retained. In a standalone negative assertion, (*AC-
+ CEPT) causes the assertion to fail without any further processing; cap-
+ tured substrings and any mark name are discarded.
If the assertion is a condition, (*ACCEPT) causes the condition to be
true for a positive assertion and false for a negative one; captured
@@ -9415,8 +9398,8 @@
These behaviours occur whether or not the group is called recursively.
(*ACCEPT) in a group called as a subroutine causes the subroutine match
- to succeed without any further processing. Matching then continues
- after the subroutine call. Perl documents this behaviour. Perl's treat-
+ to succeed without any further processing. Matching then continues af-
+ ter the subroutine call. Perl documents this behaviour. Perl's treat-
ment of the other verbs in subroutines is different in some cases.
(*FAIL) in a group called as a subroutine has its normal effect: it
@@ -9447,7 +9430,7 @@
REVISION
- Last updated: 21 June 2019
+ Last updated: 22 June 2019
Copyright (c) 1997-2019 University of Cambridge.
------------------------------------------------------------------------------
@@ -9531,9 +9514,9 @@
also reduce the memory requirements.
In contrast to pcre2_match(), pcre2_dfa_match() does use recursive
- function calls, but only for processing atomic groups, lookaround
- assertions, and recursion within the pattern. The original version of
- the code used to allocate quite large internal workspace vectors on the
+ function calls, but only for processing atomic groups, lookaround as-
+ sertions, and recursion within the pattern. The original version of the
+ code used to allocate quite large internal workspace vectors on the
stack, which caused some problems for some patterns in environments
with small stacks. From release 10.32 the code for pcre2_dfa_match()
has been re-factored to use heap memory when necessary for internal
@@ -9553,8 +9536,8 @@
(a|e|i|o|u). In general, the simplest construction that provides the
required behaviour is usually the most efficient. Jeffrey Friedl's book
contains a lot of useful general discussion about optimizing regular
- expressions for efficient performance. This document contains a few
- observations about PCRE2.
+ expressions for efficient performance. This document contains a few ob-
+ servations about PCRE2.
Using Unicode character properties (the \p, \P, and \X escapes) is
slow, because PCRE2 has to use a multi-stage table lookup whenever it
@@ -9575,11 +9558,11 @@
option is set, the pattern is implicitly anchored by PCRE2, since it
can match only at the start of a subject string. If the pattern has
multiple top-level branches, they must all be anchorable. The optimiza-
- tion can be disabled by the PCRE2_NO_DOTSTAR_ANCHOR option, and is
- automatically disabled if the pattern contains (*PRUNE) or (*SKIP).
+ tion can be disabled by the PCRE2_NO_DOTSTAR_ANCHOR option, and is au-
+ tomatically disabled if the pattern contains (*PRUNE) or (*SKIP).
- If PCRE2_DOTALL is not set, PCRE2 cannot make this optimization,
- because the dot metacharacter does not then match a newline, and if the
+ If PCRE2_DOTALL is not set, PCRE2 cannot make this optimization, be-
+ cause the dot metacharacter does not then match a newline, and if the
subject string contains newlines, the pattern may match from the char-
acter immediately following one of them instead of from the very start.
For example, the pattern
@@ -9593,8 +9576,8 @@
If you are using such a pattern with subject strings that do not con-
tain newlines, the best performance is obtained by setting
- PCRE2_DOTALL, or starting the pattern with ^.* or ^.*? to indicate
- explicit anchoring. That saves PCRE2 from having to scan along the sub-
+ PCRE2_DOTALL, or starting the pattern with ^.* or ^.*? to indicate ex-
+ plicit anchoring. That saves PCRE2 from having to scan along the sub-
ject looking for a newline to restart at.
Beware of patterns that contain nested indefinite repeats. These can
@@ -9608,8 +9591,8 @@
2, 3, or 4 times, and for each of those cases other than 0 or 4, the +
repeats can match different numbers of times.) When the remainder of
the pattern is such that the entire match is going to fail, PCRE2 has
- in principle to try every possible variation, and this can take an
- extremely long time, even for relatively short strings.
+ in principle to try every possible variation, and this can take an ex-
+ tremely long time, even for relatively short strings.
An optimization catches some of the more simple cases such as
@@ -9663,8 +9646,8 @@
matching, and on the amount of heap memory that is used. The default
values of the limits are very large, and unlikely ever to operate. They
can be changed when PCRE2 is built, and they can also be set when
- pcre2_match() or pcre2_dfa_match() is called. For details of these
- interfaces, see the pcre2build documentation and the section entitled
+ pcre2_match() or pcre2_dfa_match() is called. For details of these in-
+ terfaces, see the pcre2build documentation and the section entitled
"The match context" in the pcre2api documentation.
The pcre2test test program has a modifier called "find_limits" which,
@@ -9714,8 +9697,8 @@
This set of functions provides a POSIX-style API for the PCRE2 regular
expression 8-bit library. There are no POSIX-style wrappers for PCRE2's
- 16-bit and 32-bit libraries. See the pcre2api documentation for a
- description of PCRE2's native API, which contains much additional func-
+ 16-bit and 32-bit libraries. See the pcre2api documentation for a de-
+ scription of PCRE2's native API, which contains much additional func-
tionality.
The functions described here are wrapper functions that ultimately call
@@ -9776,11 +9759,11 @@
COMPILING A PATTERN
- The function pcre2_regcomp() is called to compile a pattern into an
- internal form. By default, the pattern is a C string terminated by a
- binary zero (but see REG_PEND below). The preg argument is a pointer to
- a regex_t structure that is used as a base for storing information
- about the compiled regular expression. (It is also used for input when
+ The function pcre2_regcomp() is called to compile a pattern into an in-
+ ternal form. By default, the pattern is a C string terminated by a bi-
+ nary zero (but see REG_PEND below). The preg argument is a pointer to a
+ regex_t structure that is used as a base for storing information about
+ the compiled regular expression. (It is also used for input when
REG_PEND is set.)
The argument cflags is either zero, or contains one or more of the bits
@@ -9816,10 +9799,10 @@
REG_NOSUB
When a pattern that is compiled with this flag is passed to
- pcre2_regexec() for matching, the nmatch and pmatch arguments are
- ignored, and no captured strings are returned. Versions of the PCRE
- library prior to 10.22 used to set the PCRE2_NO_AUTO_CAPTURE compile
- option, but this no longer happens because it disables the use of back-
+ pcre2_regexec() for matching, the nmatch and pmatch arguments are ig-
+ nored, and no captured strings are returned. Versions of the PCRE li-
+ brary prior to 10.22 used to set the PCRE2_NO_AUTO_CAPTURE compile op-
+ tion, but this no longer happens because it disables the use of back-
references.
REG_PEND
@@ -9826,8 +9809,8 @@
If this option is set, the reg_endp field in the preg structure (which
has the type const char *) must be set to point to the character beyond
- the end of the pattern before calling pcre2_regcomp(). The pattern
- itself may now contain binary zeros, which are treated as data charac-
+ the end of the pattern before calling pcre2_regcomp(). The pattern it-
+ self may now contain binary zeros, which are treated as data charac-
ters. Without REG_PEND, a binary zero terminates the pattern and the
re_endp field is ignored. This is a GNU extension to the POSIX standard
and should be used with caution in software intended to be portable to
@@ -9854,8 +9837,8 @@
Note that REG_UTF is not part of the POSIX standard.
In the absence of these flags, no options are passed to the native
- function. This means the the regex is compiled with PCRE2 default
- semantics. In particular, the way it handles newline characters in the
+ function. This means the the regex is compiled with PCRE2 default se-
+ mantics. In particular, the way it handles newline characters in the
subject string is the Perl way, not the POSIX way. Note that setting
PCRE2_MULTILINE has only some of the effects specified for REG_NEWLINE.
It does not affect the way newlines are matched by the dot metacharac-
@@ -9864,8 +9847,8 @@
The yield of pcre2_regcomp() is zero on success, and non-zero other-
wise. The preg structure is filled in on success, and one other member
of the structure (as well as re_endp) is public: re_nsub contains the
- number of capturing subpatterns in the regular expression. Various
- error codes are defined in the header file.
+ number of capturing subpatterns in the regular expression. Various er-
+ ror codes are defined in the header file.
NOTE: If the yield of pcre2_regcomp() is non-zero, you must not attempt
to use the contents of the preg structure. If, for example, you pass it
@@ -9906,8 +9889,8 @@
Default POSIX newline handling can be obtained by setting PCRE2_DOTALL
and PCRE2_DOLLAR_ENDONLY when calling pcre2_compile() directly, but
- there is no way to make PCRE2 behave exactly as for the REG_NEWLINE
- action. When using the POSIX API, passing REG_NEWLINE to PCRE2's
+ there is no way to make PCRE2 behave exactly as for the REG_NEWLINE ac-
+ tion. When using the POSIX API, passing REG_NEWLINE to PCRE2's
pcre2_regcomp() function causes PCRE2_MULTILINE to be passed to
pcre2_compile(), and REG_DOTALL passes PCRE2_DOTALL. There is no way to
pass PCRE2_DOLLAR_ENDONLY.
@@ -9941,15 +9924,15 @@
When this option is set, the subject string starts at string +
pmatch[0].rm_so and ends at string + pmatch[0].rm_eo, which should
- point to the first character beyond the string. There may be binary
- zeros within the subject string, and indeed, using REG_STARTEND is the
+ point to the first character beyond the string. There may be binary ze-
+ ros within the subject string, and indeed, using REG_STARTEND is the
only way to pass a subject string that contains a binary zero.
Whatever the value of pmatch[0].rm_so, the offsets of the matched
string and any captured substrings are still given relative to the
start of string itself. (Before PCRE2 release 10.30 these were given
- relative to string + pmatch[0].rm_so, but this differs from other
- implementations.)
+ relative to string + pmatch[0].rm_so, but this differs from other im-
+ plementations.)
This is a BSD extension, compatible with but not specified by IEEE
Standard 1003.2 (POSIX.2), and should be used with caution in software
@@ -9964,8 +9947,8 @@
pcre2_regexec() are ignored (except possibly as input for REG_STAR-
TEND).
- The value of nmatch may be zero, and the value pmatch may be NULL
- (unless REG_STARTEND is set); in both these cases no data about any
+ The value of nmatch may be zero, and the value pmatch may be NULL (un-
+ less REG_STARTEND is set); in both these cases no data about any
matched strings is returned.
Otherwise, the portion of the string that was matched, and also any
@@ -9978,9 +9961,9 @@
elements relate to the capturing subpatterns of the regular expression.
Unused entries in the array have both structure members set to -1.
- A successful match yields a zero return; various error codes are
- defined in the header file, of which REG_NOMATCH is the "expected"
- failure code.
+ A successful match yields a zero return; various error codes are de-
+ fined in the header file, of which REG_NOMATCH is the "expected" fail-
+ ure code.
ERROR MESSAGES
@@ -9989,8 +9972,8 @@
pcre2_regcomp() or pcre2_regexec() to a printable message. If preg is
not NULL, the error should have arisen from the use of that structure.
A message terminated by a binary zero is placed in errbuf. If the buf-
- fer is too short, only the first errbuf_size - 1 characters of the
- error message are used. The yield of the function is the size of buffer
+ fer is too short, only the first errbuf_size - 1 characters of the er-
+ ror message are used. The yield of the function is the size of buffer
needed to hold the whole message, including the terminating zero. This
value is greater than errbuf_size if the message was truncated.
@@ -9999,8 +9982,8 @@
Compiling a regular expression causes memory to be allocated and asso-
ciated with the preg structure. The function pcre2_regfree() frees all
- such memory, after which preg may no longer be used as a compiled
- expression.
+ such memory, after which preg may no longer be used as a compiled ex-
+ pression.
AUTHOR
@@ -10060,8 +10043,8 @@
If PCRE2 is installed elsewhere, you may need to add additional options
to the command line. For example, on a Unix-like system that has PCRE2
- installed in /usr/local, you can compile the demonstration program
- using a command like this:
+ installed in /usr/local, you can compile the demonstration program us-
+ ing a command like this:
cc -o pcre2demo -I/usr/local/include pcre2demo.c \
-L/usr/local/lib -lpcre2-8
@@ -10073,8 +10056,8 @@
./pcre2demo -g 'cat|dog' 'the dog sat on the cat'
Note that there is a much more comprehensive test program, called
- pcre2test, which supports many more facilities for testing regular
- expressions using all three PCRE2 libraries (8-bit, 16-bit, and 32-bit,
+ pcre2test, which supports many more facilities for testing regular ex-
+ pressions using all three PCRE2 libraries (8-bit, 16-bit, and 32-bit,
though not all three need be installed). The pcre2demo program is pro-
vided as a relatively simple coding example.
@@ -10210,8 +10193,8 @@
errorcode = fwrite(bytes, 1, bytescount, fd);
Note that the serialized data is binary data that may contain any of
- the 256 possible byte values. On systems that make a distinction
- between binary and non-binary data, be sure that the file is opened for
+ the 256 possible byte values. On systems that make a distinction be-
+ tween binary and non-binary data, be sure that the file is opened for
binary output.
Serializing a set of patterns leaves the original data untouched, so
@@ -10218,18 +10201,18 @@
they can still be used for matching. Their memory must eventually be
freed in the usual way by calling pcre2_code_free(). When you have fin-
ished with the byte stream, it too must be freed by calling pcre2_seri-
- alize_free(). If this function is called with a NULL argument, it
- returns immediately without doing anything.
+ alize_free(). If this function is called with a NULL argument, it re-
+ turns immediately without doing anything.
RE-USING PRECOMPILED PATTERNS
- In order to re-use a set of saved patterns you must first make the
- serialized byte stream available in main memory (for example, by read-
- ing from a file). The management of this memory block is up to the
- application. You can use the pcre2_serialize_get_number_of_codes()
- function to find out how many compiled patterns are in the serialized
- data without actually decoding the patterns:
+ In order to re-use a set of saved patterns you must first make the se-
+ rialized byte stream available in main memory (for example, by reading
+ from a file). The management of this memory block is up to the applica-
+ tion. You can use the pcre2_serialize_get_number_of_codes() function to
+ find out how many compiled patterns are in the serialized data without
+ actually decoding the patterns:
uint8_t *bytes = <serialized data>;
int32_t number_of_codes = pcre2_serialize_get_number_of_codes(bytes);
@@ -10237,8 +10220,8 @@
The pcre2_serialize_decode() function reads a byte stream and recreates
the compiled patterns in new memory blocks, setting pointers to them in
a vector. The first two arguments are a pointer to a suitable vector
- and its length, and the third argument points to a byte stream. The
- final argument is a pointer to a general context, which can be used to
+ and its length, and the third argument points to a byte stream. The fi-
+ nal argument is a pointer to a general context, which can be used to
specify custom memory mangagement functions for the decoded patterns.
If this argument is NULL, malloc() and free() are used. After deserial-
ization, the byte stream is no longer needed and can be discarded.
@@ -10250,9 +10233,9 @@
pcre2_serialize_decode(list_of_codes, 2, bytes, NULL);
If the vector is not large enough for all the patterns in the byte
- stream, it is filled with those that fit, and the remainder are
- ignored. The yield of the function is the number of decoded patterns,
- or one of the following negative error codes:
+ stream, it is filled with those that fit, and the remainder are ig-
+ nored. The yield of the function is the number of decoded patterns, or
+ one of the following negative error codes:
PCRE2_ERROR_BADDATA second argument is zero or less
PCRE2_ERROR_BADMAGIC mismatch of id bytes in the data
@@ -10266,9 +10249,9 @@
Decoded patterns can be used for matching in the usual way, and must be
freed by calling pcre2_code_free(). However, be aware that there is a
- potential race issue if you are using multiple patterns that were
- decoded from a single byte stream in a multithreaded application. A
- single copy of the character tables is used by all the decoded patterns
+ potential race issue if you are using multiple patterns that were de-
+ coded from a single byte stream in a multithreaded application. A sin-
+ gle copy of the character tables is used by all the decoded patterns
and a reference count is used to arrange for its memory to be automati-
cally freed when the last pattern is freed, but there is no locking on
this reference count. Therefore, if you want to call pcre2_code_free()
@@ -10351,8 +10334,8 @@
Note that \0dd is always an octal code. The treatment of backslash fol-
lowed by a non-zero digit is complicated; for details see the section
- "Non-printing characters" in the pcre2pattern documentation, where
- details of escape processing in EBCDIC environments are also given.
+ "Non-printing characters" in the pcre2pattern documentation, where de-
+ tails of escape processing in EBCDIC environments are also given.
\N{U+hh..} is synonymous with \x{hh..} in PCRE2 but is not supported in
EBCDIC environments. Note that \N not followed by an opening curly
bracket has a different meaning (see below).
@@ -10460,24 +10443,24 @@
Braille, Buginese, Buhid, Canadian_Aboriginal, Carian, Caucasian_Alba-
nian, Chakma, Cham, Cherokee, Common, Coptic, Cuneiform, Cypriot,
Cyrillic, Deseret, Devanagari, Dogra, Duployan, Egyptian_Hieroglyphs,
- Elbasan, Ethiopic, Georgian, Glagolitic, Gothic, Grantha, Greek,
- Gujarati, Gunjala_Gondi, Gurmukhi, Han, Hangul, Hanifi_Rohingya,
- Hanunoo, Hatran, Hebrew, Hiragana, Imperial_Aramaic, Inherited,
- Inscriptional_Pahlavi, Inscriptional_Parthian, Javanese, Kaithi, Kan-
- nada, Katakana, Kayah_Li, Kharoshthi, Khmer, Khojki, Khudawadi, Lao,
- Latin, Lepcha, Limbu, Linear_A, Linear_B, Lisu, Lycian, Lydian, Maha-
- jani, Makasar, Malayalam, Mandaic, Manichaean, Marchen, Masaram_Gondi,
- Medefaidrin, Meetei_Mayek, Mende_Kikakui, Meroitic_Cursive,
- Meroitic_Hieroglyphs, Miao, Modi, Mongolian, Mro, Multani, Myanmar,
- Nabataean, New_Tai_Lue, Newa, Nko, Nushu, Ogham, Ol_Chiki, Old_Hungar-
- ian, Old_Italic, Old_North_Arabian, Old_Permic, Old_Persian, Old_Sog-
- dian, Old_South_Arabian, Old_Turkic, Oriya, Osage, Osmanya,
- Pahawh_Hmong, Palmyrene, Pau_Cin_Hau, Phags_Pa, Phoenician,
- Psalter_Pahlavi, Rejang, Runic, Samaritan, Saurashtra, Sharada, Sha-
- vian, Siddham, SignWriting, Sinhala, Sogdian, Sora_Sompeng, Soyombo,
- Sundanese, Syloti_Nagri, Syriac, Tagalog, Tagbanwa, Tai_Le, Tai_Tham,
- Tai_Viet, Takri, Tamil, Tangut, Telugu, Thaana, Thai, Tibetan, Tifi-
- nagh, Tirhuta, Ugaritic, Vai, Warang_Citi, Yi, Zanabazar_Square.
+ Elbasan, Ethiopic, Georgian, Glagolitic, Gothic, Grantha, Greek, Gu-
+ jarati, Gunjala_Gondi, Gurmukhi, Han, Hangul, Hanifi_Rohingya, Hanunoo,
+ Hatran, Hebrew, Hiragana, Imperial_Aramaic, Inherited, Inscrip-
+ tional_Pahlavi, Inscriptional_Parthian, Javanese, Kaithi, Kannada,
+ Katakana, Kayah_Li, Kharoshthi, Khmer, Khojki, Khudawadi, Lao, Latin,
+ Lepcha, Limbu, Linear_A, Linear_B, Lisu, Lycian, Lydian, Mahajani,
+ Makasar, Malayalam, Mandaic, Manichaean, Marchen, Masaram_Gondi, Mede-
+ faidrin, Meetei_Mayek, Mende_Kikakui, Meroitic_Cursive, Meroitic_Hiero-
+ glyphs, Miao, Modi, Mongolian, Mro, Multani, Myanmar, Nabataean,
+ New_Tai_Lue, Newa, Nko, Nushu, Ogham, Ol_Chiki, Old_Hungarian,
+ Old_Italic, Old_North_Arabian, Old_Permic, Old_Persian, Old_Sogdian,
+ Old_South_Arabian, Old_Turkic, Oriya, Osage, Osmanya, Pahawh_Hmong,
+ Palmyrene, Pau_Cin_Hau, Phags_Pa, Phoenician, Psalter_Pahlavi, Rejang,
+ Runic, Samaritan, Saurashtra, Sharada, Shavian, Siddham, SignWriting,
+ Sinhala, Sogdian, Sora_Sompeng, Soyombo, Sundanese, Syloti_Nagri, Syr-
+ iac, Tagalog, Tagbanwa, Tai_Le, Tai_Tham, Tai_Viet, Takri, Tamil,
+ Tangut, Telugu, Thaana, Thai, Tibetan, Tifinagh, Tirhuta, Ugaritic,
+ Vai, Warang_Citi, Yi, Zanabazar_Square.
CHARACTER CLASSES
@@ -10604,9 +10587,9 @@
for example (?^in). An option setting may appear at the start of a non-
capture group, for example (?i:...).
- The following are recognized only at the very start of a pattern or
- after one of the newline or \R options with similar syntax. More than
- one of them may appear. For the first three, d is a decimal number.
+ The following are recognized only at the very start of a pattern or af-
+ ter one of the newline or \R options with similar syntax. More than one
+ of them may appear. For the first three, d is a decimal number.
(*LIMIT_DEPTH=d) set the backtracking limit to d
(*LIMIT_HEAP=d) set the heap size limit to d * 1024 bytes
@@ -10630,8 +10613,8 @@
NEWLINE CONVENTION
- These are recognized only at the very start of the pattern or after
- option settings with a similar syntax.
+ These are recognized only at the very start of the pattern or after op-
+ tion settings with a similar syntax.
(*CR) carriage return only
(*LF) linefeed only
@@ -10643,8 +10626,8 @@
WHAT \R MATCHES
- These are recognized only at the very start of the pattern or after
- option setting with a similar syntax.
+ These are recognized only at the very start of the pattern or after op-
+ tion setting with a similar syntax.
(*BSR_ANYCRLF) CR, LF, or CRLF
(*BSR_UNICODE) any Unicode newline sequence
@@ -10886,23 +10869,23 @@
The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly test
characters of any code value, but, by default, the characters that
PCRE2 recognizes as digits, spaces, or word characters remain the same
- set as in non-UTF mode, all with code points less than 256. This
- remains true even when PCRE2 is built to include Unicode support,
- because to do otherwise would slow down matching in many common cases.
- Note that this also applies to \b and \B, because they are defined in
- terms of \w and \W. If you want to test for a wider sense of, say,
- "digit", you can use explicit Unicode property tests such as \p{Nd}.
- Alternatively, if you set the PCRE2_UCP option, the way that the char-
- acter escapes work is changed so that Unicode properties are used to
- determine which characters match. There are more details in the section
- on generic character types in the pcre2pattern documentation.
+ set as in non-UTF mode, all with code points less than 256. This re-
+ mains true even when PCRE2 is built to include Unicode support, because
+ to do otherwise would slow down matching in many common cases. Note
+ that this also applies to \b and \B, because they are defined in terms
+ of \w and \W. If you want to test for a wider sense of, say, "digit",
+ you can use explicit Unicode property tests such as \p{Nd}. Alterna-
+ tively, if you set the PCRE2_UCP option, the way that the character es-
+ capes work is changed so that Unicode properties are used to determine
+ which characters match. There are more details in the section on
+ generic character types in the pcre2pattern documentation.
Similarly, characters that match the POSIX named character classes are
all low-valued characters, unless the PCRE2_UCP option is set.
- However, the special horizontal and vertical white space matching
- escapes (\h, \H, \v, and \V) do match all the appropriate Unicode char-
- acters, whether or not PCRE2_UCP is set.
+ However, the special horizontal and vertical white space matching es-
+ capes (\h, \H, \v, and \V) do match all the appropriate Unicode charac-
+ ters, whether or not PCRE2_UCP is set.
CASE-EQUIVALENCE IN UTF MODE
@@ -10947,12 +10930,12 @@
are only normally used with a small number of scripts. For example,
U+102E0 (Coptic Epact thousands mark) is used only with Arabic and Cop-
tic. In order to make it possible to check this, a Unicode property
- called Script Extension exists. Its value is a list of scripts that
- apply to the character. For the majority of characters, the list con-
- tains just one script, the same one as the Script property. However,
- for characters such as U+102E0 more than one Script is listed. There
- are also some Common characters that have a single, non-Common script
- in their Script Extension list.
+ called Script Extension exists. Its value is a list of scripts that ap-
+ ply to the character. For the majority of characters, the list contains
+ just one script, the same one as the Script property. However, for
+ characters such as U+102E0 more than one Script is listed. There are
+ also some Common characters that have a single, non-Common script in
+ their Script Extension list.
The next section describes the basic rules for deciding whether a given
string of characters is a script run. Note, however, that there are
@@ -10989,8 +10972,8 @@
The first has the Script Extension list Arabic, Hanifi Rohingya, Syr-
iac, and Thaana; the second has just Arabic and Hanifi Rohingya. Both
- of them could appear in script runs of either Arabic or Hanifi
- Rohingya. The first could also appear in Syriac or Thaana script runs,
+ of them could appear in script runs of either Arabic or Hanifi Ro-
+ hingya. The first could also appear in Syriac or Thaana script runs,
but the second could not.
The Chinese Han script
@@ -11004,8 +10987,8 @@
gana, Katakana, and Han, or a mixture of Hangul and Han, or a mixture
of Bopomofo and Han, but not, for example, a mixture of Hangul and
Bopomofo and Han. PCRE2 (like Perl) follows Unicode's Technical Stan-
- dard 39 ("Unicode Security Mechanisms", http://uni-
- code.org/reports/tr39/) in allowing such mixtures.
+ dard 39 ("Unicode Security Mechanisms", http://unicode.org/re-
+ ports/tr39/) in allowing such mixtures.
Decimal digits
@@ -11012,8 +10995,8 @@
Unicode contains many sets of 10 decimal digits in different scripts,
and some scripts (including the Common script) contain more than one
set. Some of these decimal digits them are visually indistinguishable
- from the common ASCII digits. In addition to the script checking
- described above, if a script run contains any decimal digits, they must
+ from the common ASCII digits. In addition to the script checking de-
+ scribed above, if a script run contains any decimal digits, they must
all come from the same set of 10 adjacent characters.
@@ -11022,8 +11005,8 @@
When the PCRE2_UTF option is set, the strings passed as patterns and
subjects are (by default) checked for validity on entry to the relevant
functions. If an invalid UTF string is passed, a negative error code is
- returned. The code unit offset to the offending character can be
- extracted from the match data block by calling pcre2_get_startchar(),
+ returned. The code unit offset to the offending character can be ex-
+ tracted from the match data block by calling pcre2_get_startchar(),
which is used for this purpose after a UTF error.
In some situations, you may already know that your strings are valid,
@@ -11072,16 +11055,16 @@
UTF-16, where they are used in pairs to encode code points with values
greater than 0xFFFF. The code points that are encoded by UTF-16 pairs
are available independently in the UTF-8 and UTF-32 encodings. (In
- other words, the whole surrogate thing is a fudge for UTF-16 which
- unfortunately messes up UTF-8 and UTF-32.)
+ other words, the whole surrogate thing is a fudge for UTF-16 which un-
+ fortunately messes up UTF-8 and UTF-32.)
Setting PCRE2_NO_UTF_CHECK at compile time does not disable the error
that is given if an escape sequence for an invalid Unicode code point
is encountered in the pattern. If you want to allow escape sequences
- such as \x{d800} (a surrogate code point) you can set the
- PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES extra option. However, this is pos-
- sible only in UTF-8 and UTF-32 modes, because these values are not rep-
- resentable in UTF-16.
+ such as \x{d800} (a surrogate code point) you can set the PCRE2_EX-
+ TRA_ALLOW_SURROGATE_ESCAPES extra option. However, this is possible
+ only in UTF-8 and UTF-32 modes, because these values are not repre-
+ sentable in UTF-16.
Errors in UTF-8 strings
@@ -11171,18 +11154,18 @@
MATCHING IN INVALID UTF STRINGS
You can run pattern matches on subject strings that may contain invalid
- UTF sequences if you call pcre2_compile() with the
- PCRE2_MATCH_INVALID_UTF option. This is supported by pcre2_match(),
- including JIT matching, but not by pcre2_dfa_match(). When
- PCRE2_MATCH_INVALID_UTF is set, it forces PCRE2_UTF to be set as well.
- Note, however, that the pattern itself must be a valid UTF string.
+ UTF sequences if you call pcre2_compile() with the PCRE2_MATCH_IN-
+ VALID_UTF option. This is supported by pcre2_match(), including JIT
+ matching, but not by pcre2_dfa_match(). When PCRE2_MATCH_INVALID_UTF is
+ set, it forces PCRE2_UTF to be set as well. Note, however, that the
+ pattern itself must be a valid UTF string.
Setting PCRE2_MATCH_INVALID_UTF does not affect what pcre2_compile()
generates, but if pcre2_jit_compile() is subsequently called, it does
generate different code. If JIT is not used, the option affects the be-
- haviour of the interpretive code in pcre2_match(). When
- PCRE2_MATCH_INVALID_UTF is set at compile time, PCRE2_NO_UTF_CHECK is
- ignored at match time.
+ haviour of the interpretive code in pcre2_match(). When PCRE2_MATCH_IN-
+ VALID_UTF is set at compile time, PCRE2_NO_UTF_CHECK is ignored at
+ match time.
In this mode, an invalid code unit sequence in the subject never
matches any pattern item. It does not match dot, it does not match
Modified: code/trunk/doc/pcre2grep.txt
===================================================================
--- code/trunk/doc/pcre2grep.txt 2019-06-21 16:10:17 UTC (rev 1117)
+++ code/trunk/doc/pcre2grep.txt 2019-06-22 16:36:15 UTC (rev 1118)
@@ -12,11 +12,11 @@
DESCRIPTION
pcre2grep searches files for character patterns, in the same way as
- other grep commands do, but it uses the PCRE2 regular expression
- library to support patterns that are compatible with the regular
- expressions of Perl 5. See pcre2syntax(3) for a quick-reference summary
- of pattern syntax, or pcre2pattern(3) for a full description of the
- syntax and semantics of the regular expressions that PCRE2 supports.
+ other grep commands do, but it uses the PCRE2 regular expression li-
+ brary to support patterns that are compatible with the regular expres-
+ sions of Perl 5. See pcre2syntax(3) for a quick-reference summary of
+ pattern syntax, or pcre2pattern(3) for a full description of the syntax
+ and semantics of the regular expressions that PCRE2 supports.
Patterns, whether supplied on the command line or in a separate file,
are given without delimiters. For example:
@@ -26,8 +26,8 @@
If you attempt to use delimiters (for example, by surrounding a pattern
with slashes, as is common in Perl scripts), they are interpreted as
part of the pattern. Quotes can of course be used to delimit patterns
- on the command line because they are interpreted by the shell, and
- indeed quotes are required if a pattern contains white space or shell
+ on the command line because they are interpreted by the shell, and in-
+ deed quotes are required if a pattern contains white space or shell
metacharacters.
The first argument that follows any option settings is treated as the
@@ -54,8 +54,8 @@
controlled by parameters that can be set by the --buffer-size and
--max-buffer-size options. The first of these sets the size of buffer
that is obtained at the start of processing. If an input file contains
- very long lines, a larger buffer may be needed; this is handled by
- automatically extending the buffer, up to the limit specified by --max-
+ very long lines, a larger buffer may be needed; this is handled by au-
+ tomatically extending the buffer, up to the limit specified by --max-
buffer-size. The default values for these parameters can be set when
pcre2grep is built; if nothing is specified, the defaults are set to
20KiB and 1MiB respectively. An error occurs if a line is too long and
@@ -75,12 +75,12 @@
By default, as soon as one pattern matches a line, no further patterns
are considered. However, if --colour (or --color) is used to colour the
matching substrings, or if --only-matching, --file-offsets, or --line-
- offsets is used to output only the part of the line that matched
- (either shown literally, or as an offset), scanning resumes immediately
+ offsets is used to output only the part of the line that matched (ei-
+ ther shown literally, or as an offset), scanning resumes immediately
following the match, so that further matches on the same line can be
- found. If there are multiple patterns, they are all tried on the
- remainder of the line, but patterns that follow the one that matched
- are not tried on the earlier part of the line.
+ found. If there are multiple patterns, they are all tried on the re-
+ mainder of the line, but patterns that follow the one that matched are
+ not tried on the earlier part of the line.
This behaviour means that the order in which multiple patterns are
specified can affect the output when one of the above options is used.
@@ -89,11 +89,11 @@
overlap).
Patterns that can match an empty string are accepted, but empty string
- matches are never recognized. An example is the pattern
- "(super)?(man)?", in which all components are optional. This pattern
- finds all occurrences of both "super" and "man"; the output differs
- from matching with "super|man" when only the matching substrings are
- being shown.
+ matches are never recognized. An example is the pattern "(su-
+ per)?(man)?", in which all components are optional. This pattern finds
+ all occurrences of both "super" and "man"; the output differs from
+ matching with "super|man" when only the matching substrings are being
+ shown.
If the LC_ALL or LC_CTYPE environment variable is set, pcre2grep uses
the value to set a locale when calling the PCRE2 library. The --locale
@@ -116,153 +116,152 @@
By default, a file that contains a binary zero byte within the first
1024 bytes is identified as a binary file, and is processed specially.
(GNU grep identifies binary files in this manner.) However, if the new-
- line type is specified as "nul", that is, the line terminator is a
- binary zero, the test for a binary file is not applied. See the
- --binary-files option for a means of changing the way binary files are
- handled.
+ line type is specified as "nul", that is, the line terminator is a bi-
+ nary zero, the test for a binary file is not applied. See the --binary-
+ files option for a means of changing the way binary files are handled.
BINARY ZEROS IN PATTERNS
- Patterns passed from the command line are strings that are terminated
- by a binary zero, so cannot contain internal zeros. However, patterns
+ Patterns passed from the command line are strings that are terminated
+ by a binary zero, so cannot contain internal zeros. However, patterns
that are read from a file via the -f option may contain binary zeros.
OPTIONS
- The order in which some of the options appear can affect the output.
- For example, both the -H and -l options affect the printing of file
- names. Whichever comes later in the command line will be the one that
- takes effect. Similarly, except where noted below, if an option is
- given twice, the later setting is used. Numerical values for options
- may be followed by K or M, to signify multiplication by 1024 or
+ The order in which some of the options appear can affect the output.
+ For example, both the -H and -l options affect the printing of file
+ names. Whichever comes later in the command line will be the one that
+ takes effect. Similarly, except where noted below, if an option is
+ given twice, the later setting is used. Numerical values for options
+ may be followed by K or M, to signify multiplication by 1024 or
1024*1024 respectively.
-- This terminates the list of options. It is useful if the next
- item on the command line starts with a hyphen but is not an
- option. This allows for the processing of patterns and file
+ item on the command line starts with a hyphen but is not an
+ option. This allows for the processing of patterns and file
names that start with hyphens.
-A number, --after-context=number
- Output up to number lines of context after each matching
- line. Fewer lines are output if the next match or the end of
- the file is reached, or if the processing buffer size has
- been set too small. If file names and/or line numbers are
- being output, a hyphen separator is used instead of a colon
- for the context lines. A line containing "--" is output
- between each group of lines, unless they are in fact contigu-
- ous in the input file. The value of number is expected to be
- relatively small. When -c is used, -A is ignored.
+ Output up to number lines of context after each matching
+ line. Fewer lines are output if the next match or the end of
+ the file is reached, or if the processing buffer size has
+ been set too small. If file names and/or line numbers are be-
+ ing output, a hyphen separator is used instead of a colon for
+ the context lines. A line containing "--" is output between
+ each group of lines, unless they are in fact contiguous in
+ the input file. The value of number is expected to be rela-
+ tively small. When -c is used, -A is ignored.
-a, --text
- Treat binary files as text. This is equivalent to --binary-
+ Treat binary files as text. This is equivalent to --binary-
files=text.
-B number, --before-context=number
- Output up to number lines of context before each matching
- line. Fewer lines are output if the previous match or the
- start of the file is within number lines, or if the process-
- ing buffer size has been set too small. If file names and/or
- line numbers are being output, a hyphen separator is used
- instead of a colon for the context lines. A line containing
- "--" is output between each group of lines, unless they are
- in fact contiguous in the input file. The value of number is
- expected to be relatively small. When -c is used, -B is
- ignored.
+ Output up to number lines of context before each matching
+ line. Fewer lines are output if the previous match or the
+ start of the file is within number lines, or if the process-
+ ing buffer size has been set too small. If file names and/or
+ line numbers are being output, a hyphen separator is used in-
+ stead of a colon for the context lines. A line containing
+ "--" is output between each group of lines, unless they are
+ in fact contiguous in the input file. The value of number is
+ expected to be relatively small. When -c is used, -B is ig-
+ nored.
--binary-files=word
- Specify how binary files are to be processed. If the word is
- "binary" (the default), pattern matching is performed on
- binary files, but the only output is "Binary file <name>
- matches" when a match succeeds. If the word is "text", which
- is equivalent to the -a or --text option, binary files are
- processed in the same way as any other file. In this case,
- when a match succeeds, the output may be binary garbage,
- which can have nasty effects if sent to a terminal. If the
- word is "without-match", which is equivalent to the -I
- option, binary files are not processed at all; they are
- assumed not to be of interest and are skipped without causing
- any output or affecting the return code.
+ Specify how binary files are to be processed. If the word is
+ "binary" (the default), pattern matching is performed on bi-
+ nary files, but the only output is "Binary file <name>
+ matches" when a match succeeds. If the word is "text", which
+ is equivalent to the -a or --text option, binary files are
+ processed in the same way as any other file. In this case,
+ when a match succeeds, the output may be binary garbage,
+ which can have nasty effects if sent to a terminal. If the
+ word is "without-match", which is equivalent to the -I op-
+ tion, binary files are not processed at all; they are assumed
+ not to be of interest and are skipped without causing any
+ output or affecting the return code.
--buffer-size=number
- Set the parameter that controls how much memory is obtained
+ Set the parameter that controls how much memory is obtained
at the start of processing for buffering files that are being
scanned. See also --max-buffer-size below.
-C number, --context=number
- Output number lines of context both before and after each
- matching line. This is equivalent to setting both -A and -B
+ Output number lines of context both before and after each
+ matching line. This is equivalent to setting both -A and -B
to the same value.
-c, --count
- Do not output lines from the files that are being scanned;
- instead output the number of lines that would have been
+ Do not output lines from the files that are being scanned;
+ instead output the number of lines that would have been
shown, either because they matched, or, if -v is set, because
- they failed to match. By default, this count is exactly the
- same as the number of lines that would have been output, but
- if the -M (multiline) option is used (without -v), there may
- be more suppressed lines than the count (that is, the number
+ they failed to match. By default, this count is exactly the
+ same as the number of lines that would have been output, but
+ if the -M (multiline) option is used (without -v), there may
+ be more suppressed lines than the count (that is, the number
of matches).
- If no lines are selected, the number zero is output. If sev-
- eral files are are being scanned, a count is output for each
- of them and the -t option can be used to cause a total to be
- output at the end. However, if the --files-with-matches
- option is also used, only those files whose counts are
- greater than zero are listed. When -c is used, the -A, -B,
- and -C options are ignored.
+ If no lines are selected, the number zero is output. If sev-
+ eral files are are being scanned, a count is output for each
+ of them and the -t option can be used to cause a total to be
+ output at the end. However, if the --files-with-matches op-
+ tion is also used, only those files whose counts are greater
+ than zero are listed. When -c is used, the -A, -B, and -C op-
+ tions are ignored.
--colour, --color
If this option is given without any data, it is equivalent to
- "--colour=auto". If data is required, it must be given in
+ "--colour=auto". If data is required, it must be given in
the same shell item, separated by an equals sign.
--colour=value, --color=value
This option specifies under what circumstances the parts of a
line that matched a pattern should be coloured in the output.
- By default, the output is not coloured. The value (which is
- optional, see above) may be "never", "always", or "auto". In
- the latter case, colouring happens only if the standard out-
- put is connected to a terminal. More resources are used when
+ By default, the output is not coloured. The value (which is
+ optional, see above) may be "never", "always", or "auto". In
+ the latter case, colouring happens only if the standard out-
+ put is connected to a terminal. More resources are used when
colouring is enabled, because pcre2grep has to search for all
- possible matches in a line, not just one, in order to colour
+ possible matches in a line, not just one, in order to colour
them all.
- The colour that is used can be specified by setting one of
- the environment variables PCRE2GREP_COLOUR, PCRE2GREP_COLOR,
+ The colour that is used can be specified by setting one of
+ the environment variables PCRE2GREP_COLOUR, PCRE2GREP_COLOR,
PCREGREP_COLOUR, or PCREGREP_COLOR, which are checked in that
order. If none of these are set, pcre2grep looks for
- GREP_COLORS or GREP_COLOR (in that order). The value of the
- variable should be a string of two numbers, separated by a
- semicolon, except in the case of GREP_COLORS, which must
+ GREP_COLORS or GREP_COLOR (in that order). The value of the
+ variable should be a string of two numbers, separated by a
+ semicolon, except in the case of GREP_COLORS, which must
start with "ms=" or "mt=" followed by two semicolon-separated
- colours, terminated by the end of the string or by a colon.
- If GREP_COLORS does not start with "ms=" or "mt=" it is
- ignored, and GREP_COLOR is checked.
+ colours, terminated by the end of the string or by a colon.
+ If GREP_COLORS does not start with "ms=" or "mt=" it is ig-
+ nored, and GREP_COLOR is checked.
- If the string obtained from one of the above variables con-
+ If the string obtained from one of the above variables con-
tains any characters other than semicolon or digits, the set-
ting is ignored and the default colour is used. The string is
copied directly into the control string for setting colour on
- a terminal, so it is your responsibility to ensure that the
- values make sense. If no relevant environment variable is
+ a terminal, so it is your responsibility to ensure that the
+ values make sense. If no relevant environment variable is
set, the default is "1;31", which gives red.
-D action, --devices=action
- If an input path is not a regular file or a directory,
- "action" specifies how it is to be processed. Valid values
- are "read" (the default) or "skip" (silently skip the path).
+ If an input path is not a regular file or a directory, "ac-
+ tion" specifies how it is to be processed. Valid values are
+ "read" (the default) or "skip" (silently skip the path).
-d action, --directories=action
If an input path is a directory, "action" specifies how it is
- to be processed. Valid values are "read" (the default in
- non-Windows environments, for compatibility with GNU grep),
- "recurse" (equivalent to the -r option), or "skip" (silently
- skip the path, the default in Windows environments). In the
- "read" case, directories are read as if they were ordinary
- files. In some operating systems the effect of reading a
- directory like this is an immediate end-of-file; in others it
+ to be processed. Valid values are "read" (the default in
+ non-Windows environments, for compatibility with GNU grep),
+ "recurse" (equivalent to the -r option), or "skip" (silently
+ skip the path, the default in Windows environments). In the
+ "read" case, directories are read as if they were ordinary
+ files. In some operating systems the effect of reading a di-
+ rectory like this is an immediate end-of-file; in others it
may provoke an error.
--depth-limit=number
@@ -271,142 +270,142 @@
-e pattern, --regex=pattern, --regexp=pattern
Specify a pattern to be matched. This option can be used mul-
tiple times in order to specify several patterns. It can also
- be used as a way of specifying a single pattern that starts
- with a hyphen. When -e is used, no argument pattern is taken
- from the command line; all arguments are treated as file
- names. There is no limit to the number of patterns. They are
- applied to each line in the order in which they are defined
+ be used as a way of specifying a single pattern that starts
+ with a hyphen. When -e is used, no argument pattern is taken
+ from the command line; all arguments are treated as file
+ names. There is no limit to the number of patterns. They are
+ applied to each line in the order in which they are defined
until one matches.
- If -f is used with -e, the command line patterns are matched
+ If -f is used with -e, the command line patterns are matched
first, followed by the patterns from the file(s), independent
- of the order in which these options are specified. Note that
- multiple use of -e is not the same as a single pattern with
+ of the order in which these options are specified. Note that
+ multiple use of -e is not the same as a single pattern with
alternatives. For example, X|Y finds the first character in a
- line that is X or Y, whereas if the two patterns are given
+ line that is X or Y, whereas if the two patterns are given
separately, with X first, pcre2grep finds X if it is present,
even if it follows Y in the line. It finds Y only if there is
- no X in the line. This matters only if you are using -o or
+ no X in the line. This matters only if you are using -o or
--colo(u)r to show the part(s) of the line that matched.
--exclude=pattern
Files (but not directories) whose names match the pattern are
- skipped without being processed. This applies to all files,
- whether listed on the command line, obtained from --file-
+ skipped without being processed. This applies to all files,
+ whether listed on the command line, obtained from --file-
list, or by scanning a directory. The pattern is a PCRE2 reg-
- ular expression, and is matched against the final component
- of the file name, not the entire path. The -F, -w, and -x
- options do not apply to this pattern. The option may be given
+ ular expression, and is matched against the final component
+ of the file name, not the entire path. The -F, -w, and -x op-
+ tions do not apply to this pattern. The option may be given
any number of times in order to specify multiple patterns. If
- a file name matches both an --include and an --exclude pat-
+ a file name matches both an --include and an --exclude pat-
tern, it is excluded. There is no short form for this option.
--exclude-from=filename
- Treat each non-empty line of the file as the data for an
+ Treat each non-empty line of the file as the data for an
--exclude option. What constitutes a newline when reading the
- file is the operating system's default. The --newline option
- has no effect on this option. This option may be given more
+ file is the operating system's default. The --newline option
+ has no effect on this option. This option may be given more
than once in order to specify a number of files to read.
--exclude-dir=pattern
Directories whose names match the pattern are skipped without
- being processed, whatever the setting of the --recursive
- option. This applies to all directories, whether listed on
- the command line, obtained from --file-list, or by scanning a
- parent directory. The pattern is a PCRE2 regular expression,
- and is matched against the final component of the directory
- name, not the entire path. The -F, -w, and -x options do not
- apply to this pattern. The option may be given any number of
- times in order to specify more than one pattern. If a direc-
- tory matches both --include-dir and --exclude-dir, it is
- excluded. There is no short form for this option.
+ being processed, whatever the setting of the --recursive op-
+ tion. This applies to all directories, whether listed on the
+ command line, obtained from --file-list, or by scanning a
+ parent directory. The pattern is a PCRE2 regular expression,
+ and is matched against the final component of the directory
+ name, not the entire path. The -F, -w, and -x options do not
+ apply to this pattern. The option may be given any number of
+ times in order to specify more than one pattern. If a direc-
+ tory matches both --include-dir and --exclude-dir, it is ex-
+ cluded. There is no short form for this option.
-F, --fixed-strings
- Interpret each data-matching pattern as a list of fixed
- strings, separated by newlines, instead of as a regular
- expression. What constitutes a newline for this purpose is
- controlled by the --newline option. The -w (match as a word)
- and -x (match whole line) options can be used with -F. They
- apply to each of the fixed strings. A line is selected if any
+ Interpret each data-matching pattern as a list of fixed
+ strings, separated by newlines, instead of as a regular ex-
+ pression. What constitutes a newline for this purpose is con-
+ trolled by the --newline option. The -w (match as a word) and
+ -x (match whole line) options can be used with -F. They ap-
+ ply to each of the fixed strings. A line is selected if any
of the fixed strings are found in it (subject to -w or -x, if
- present). This option applies only to the patterns that are
- matched against the contents of files; it does not apply to
- patterns specified by any of the --include or --exclude
- options.
+ present). This option applies only to the patterns that are
+ matched against the contents of files; it does not apply to
+ patterns specified by any of the --include or --exclude op-
+ tions.
-f filename, --file=filename
- Read patterns from the file, one per line, and match them
- against each line of input. As is the case with patterns on
- the command line, no delimiters should be used. What consti-
- tutes a newline when reading the file is the operating sys-
- tem's default interpretation of \n. The --newline option has
- no effect on this option. Trailing white space is removed
- from each line, and blank lines are ignored. An empty file
- contains no patterns and therefore matches nothing. Patterns
- read from a file in this way may contain binary zeros, which
- are treated as ordinary data characters. See also the com-
- ments about multiple patterns versus a single pattern with
+ Read patterns from the file, one per line, and match them
+ against each line of input. As is the case with patterns on
+ the command line, no delimiters should be used. What consti-
+ tutes a newline when reading the file is the operating sys-
+ tem's default interpretation of \n. The --newline option has
+ no effect on this option. Trailing white space is removed
+ from each line, and blank lines are ignored. An empty file
+ contains no patterns and therefore matches nothing. Patterns
+ read from a file in this way may contain binary zeros, which
+ are treated as ordinary data characters. See also the com-
+ ments about multiple patterns versus a single pattern with
alternatives in the description of -e above.
- If this option is given more than once, all the specified
- files are read. A data line is output if any of the patterns
- match it. A file name can be given as "-" to refer to the
- standard input. When -f is used, patterns specified on the
- command line using -e may also be present; they are tested
- before the file's patterns. However, no other pattern is
+ If this option is given more than once, all the specified
+ files are read. A data line is output if any of the patterns
+ match it. A file name can be given as "-" to refer to the
+ standard input. When -f is used, patterns specified on the
+ command line using -e may also be present; they are tested
+ before the file's patterns. However, no other pattern is
taken from the command line; all arguments are treated as the
names of paths to be searched.
--file-list=filename
- Read a list of files and/or directories that are to be
+ Read a list of files and/or directories that are to be
scanned from the given file, one per line. What constitutes a
- newline when reading the file is the operating system's
- default. Trailing white space is removed from each line, and
+ newline when reading the file is the operating system's de-
+ fault. Trailing white space is removed from each line, and
blank lines are ignored. These paths are processed before any
- that are listed on the command line. The file name can be
- given as "-" to refer to the standard input. If --file and
- --file-list are both specified as "-", patterns are read
- first. This is useful only when the standard input is a ter-
- minal, from which further lines (the list of files) can be
+ that are listed on the command line. The file name can be
+ given as "-" to refer to the standard input. If --file and
+ --file-list are both specified as "-", patterns are read
+ first. This is useful only when the standard input is a ter-
+ minal, from which further lines (the list of files) can be
read after an end-of-file indication. If this option is given
more than once, all the specified files are read.
--file-offsets
- Instead of showing lines or parts of lines that match, show
- each match as an offset from the start of the file and a
- length, separated by a comma. In this mode, no context is
- shown. That is, the -A, -B, and -C options are ignored. If
+ Instead of showing lines or parts of lines that match, show
+ each match as an offset from the start of the file and a
+ length, separated by a comma. In this mode, no context is
+ shown. That is, the -A, -B, and -C options are ignored. If
there is more than one match in a line, each of them is shown
- separately. This option is mutually exclusive with --output,
+ separately. This option is mutually exclusive with --output,
--line-offsets, and --only-matching.
-H, --with-filename
- Force the inclusion of the file name at the start of output
+ Force the inclusion of the file name at the start of output
lines when searching a single file. By default, the file name
is not shown in this case. For matching lines, the file name
is followed by a colon; for context lines, a hyphen separator
- is used. If a line number is also being output, it follows
- the file name. When the -M option causes a pattern to match
- more than one line, only the first is preceded by the file
- name. This option overrides any previous -h, -l, or -L
- options.
+ is used. If a line number is also being output, it follows
+ the file name. When the -M option causes a pattern to match
+ more than one line, only the first is preceded by the file
+ name. This option overrides any previous -h, -l, or -L op-
+ tions.
-h, --no-filename
Suppress the output file names when searching multiple files.
- By default, file names are shown when multiple files are
- searched. For matching lines, the file name is followed by a
- colon; for context lines, a hyphen separator is used. If a
- line number is also being output, it follows the file name.
+ By default, file names are shown when multiple files are
+ searched. For matching lines, the file name is followed by a
+ colon; for context lines, a hyphen separator is used. If a
+ line number is also being output, it follows the file name.
This option overrides any previous -H, -L, or -l options.
--heap-limit=number
See --match-limit below.
- --help Output a help message, giving brief details of the command
- options and file type support, and then exit. Anything else
+ --help Output a help message, giving brief details of the command
+ options and file type support, and then exit. Anything else
on the command line is ignored.
- -I Ignore binary files. This is equivalent to --binary-
+ -I Ignore binary files. This is equivalent to --binary-
files=without-match.
-i, --ignore-case
@@ -413,56 +412,56 @@
Ignore upper/lower case distinctions during comparisons.
--include=pattern
- If any --include patterns are specified, the only files that
- are processed are those that match one of the patterns (and
- do not match an --exclude pattern). This option does not
- affect directories, but it applies to all files, whether
- listed on the command line, obtained from --file-list, or by
- scanning a directory. The pattern is a PCRE2 regular expres-
- sion, and is matched against the final component of the file
- name, not the entire path. The -F, -w, and -x options do not
- apply to this pattern. The option may be given any number of
- times. If a file name matches both an --include and an
- --exclude pattern, it is excluded. There is no short form
- for this option.
+ If any --include patterns are specified, the only files that
+ are processed are those that match one of the patterns (and
+ do not match an --exclude pattern). This option does not af-
+ fect directories, but it applies to all files, whether listed
+ on the command line, obtained from --file-list, or by scan-
+ ning a directory. The pattern is a PCRE2 regular expression,
+ and is matched against the final component of the file name,
+ not the entire path. The -F, -w, and -x options do not apply
+ to this pattern. The option may be given any number of times.
+ If a file name matches both an --include and an --exclude
+ pattern, it is excluded. There is no short form for this op-
+ tion.
--include-from=filename
- Treat each non-empty line of the file as the data for an
+ Treat each non-empty line of the file as the data for an
--include option. What constitutes a newline for this purpose
- is the operating system's default. The --newline option has
+ is the operating system's default. The --newline option has
no effect on this option. This option may be given any number
of times; all the files are read.
--include-dir=pattern
- If any --include-dir patterns are specified, the only direc-
- tories that are processed are those that match one of the
- patterns (and do not match an --exclude-dir pattern). This
- applies to all directories, whether listed on the command
- line, obtained from --file-list, or by scanning a parent
- directory. The pattern is a PCRE2 regular expression, and is
- matched against the final component of the directory name,
- not the entire path. The -F, -w, and -x options do not apply
+ If any --include-dir patterns are specified, the only direc-
+ tories that are processed are those that match one of the
+ patterns (and do not match an --exclude-dir pattern). This
+ applies to all directories, whether listed on the command
+ line, obtained from --file-list, or by scanning a parent di-
+ rectory. The pattern is a PCRE2 regular expression, and is
+ matched against the final component of the directory name,
+ not the entire path. The -F, -w, and -x options do not apply
to this pattern. The option may be given any number of times.
- If a directory matches both --include-dir and --exclude-dir,
+ If a directory matches both --include-dir and --exclude-dir,
it is excluded. There is no short form for this option.
-L, --files-without-match
- Instead of outputting lines from the files, just output the
- names of the files that do not contain any lines that would
- have been output. Each file name is output once, on a sepa-
- rate line. This option overrides any previous -H, -h, or -l
+ Instead of outputting lines from the files, just output the
+ names of the files that do not contain any lines that would
+ have been output. Each file name is output once, on a sepa-
+ rate line. This option overrides any previous -H, -h, or -l
options.
-l, --files-with-matches
- Instead of outputting lines from the files, just output the
+ Instead of outputting lines from the files, just output the
names of the files containing lines that would have been out-
- put. Each file name is output once, on a separate line.
- Searching normally stops as soon as a matching line is found
- in a file. However, if the -c (count) option is also used,
- matching continues in order to obtain the correct count, and
- those files that have at least one match are listed along
+ put. Each file name is output once, on a separate line.
+ Searching normally stops as soon as a matching line is found
+ in a file. However, if the -c (count) option is also used,
+ matching continues in order to obtain the correct count, and
+ those files that have at least one match are listed along
with their counts. Using this option with -c is a way of sup-
- pressing the listing of files with no matches. This opeion
+ pressing the listing of files with no matches. This opeion
overrides any previous -H, -h, or -L options.
--label=name
@@ -471,312 +470,312 @@
input)" is used. There is no short form for this option.
--line-buffered
- When this option is given, non-compressed input is read and
- processed line by line, and the output is flushed after each
- write. By default, input is read in large chunks, unless
- pcre2grep can determine that it is reading from a terminal
- (which is currently possible only in Unix-like environments
- or Windows). Output to terminal is normally automatically
- flushed by the operating system. This option can be useful
+ When this option is given, non-compressed input is read and
+ processed line by line, and the output is flushed after each
+ write. By default, input is read in large chunks, unless
+ pcre2grep can determine that it is reading from a terminal
+ (which is currently possible only in Unix-like environments
+ or Windows). Output to terminal is normally automatically
+ flushed by the operating system. This option can be useful
when the input or output is attached to a pipe and you do not
- want pcre2grep to buffer up large amounts of data. However,
- its use will affect performance, and the -M (multiline)
- option ceases to work. When input is from a compressed .gz or
+ want pcre2grep to buffer up large amounts of data. However,
+ its use will affect performance, and the -M (multiline) op-
+ tion ceases to work. When input is from a compressed .gz or
.bz2 file, --line-buffered is ignored.
--line-offsets
- Instead of showing lines or parts of lines that match, show
+ Instead of showing lines or parts of lines that match, show
each match as a line number, the offset from the start of the
- line, and a length. The line number is terminated by a colon
- (as usual; see the -n option), and the offset and length are
- separated by a comma. In this mode, no context is shown.
- That is, the -A, -B, and -C options are ignored. If there is
- more than one match in a line, each of them is shown sepa-
- rately. This option is mutually exclusive with --output,
+ line, and a length. The line number is terminated by a colon
+ (as usual; see the -n option), and the offset and length are
+ separated by a comma. In this mode, no context is shown.
+ That is, the -A, -B, and -C options are ignored. If there is
+ more than one match in a line, each of them is shown sepa-
+ rately. This option is mutually exclusive with --output,
--file-offsets, and --only-matching.
--locale=locale-name
- This option specifies a locale to be used for pattern match-
- ing. It overrides the value in the LC_ALL or LC_CTYPE envi-
- ronment variables. If no locale is specified, the PCRE2
- library's default (usually the "C" locale) is used. There is
- no short form for this option.
+ This option specifies a locale to be used for pattern match-
+ ing. It overrides the value in the LC_ALL or LC_CTYPE envi-
+ ronment variables. If no locale is specified, the PCRE2 li-
+ brary's default (usually the "C" locale) is used. There is no
+ short form for this option.
--match-limit=number
- Processing some regular expression patterns may take a very
+ Processing some regular expression patterns may take a very
long time to search for all possible matching strings. Others
- may require a very large amount of memory. There are three
+ may require a very large amount of memory. There are three
options that set resource limits for matching.
The --match-limit option provides a means of limiting comput-
- ing resource usage when processing patterns that are not
- going to match, but which have a very large number of possi-
- bilities in their search trees. The classic example is a pat-
- tern that uses nested unlimited repeats. Internally, PCRE2
- has a counter that is incremented each time around its main
- processing loop. If the value set by --match-limit is
- reached, an error occurs.
+ ing resource usage when processing patterns that are not go-
+ ing to match, but which have a very large number of possibil-
+ ities in their search trees. The classic example is a pattern
+ that uses nested unlimited repeats. Internally, PCRE2 has a
+ counter that is incremented each time around its main pro-
+ cessing loop. If the value set by --match-limit is reached,
+ an error occurs.
- The --heap-limit option specifies, as a number of kibibytes
- (units of 1024 bytes), the amount of heap memory that may be
+ The --heap-limit option specifies, as a number of kibibytes
+ (units of 1024 bytes), the amount of heap memory that may be
used for matching. Heap memory is needed only if matching the
- pattern requires a significant number of nested backtracking
+ pattern requires a significant number of nested backtracking
points to be remembered. This parameter can be set to zero to
forbid the use of heap memory altogether.
- The --depth-limit option limits the depth of nested back-
+ The --depth-limit option limits the depth of nested back-
tracking points, which indirectly limits the amount of memory
that is used. The amount of memory needed for each backtrack-
- ing point depends on the number of capturing parentheses in
+ ing point depends on the number of capturing parentheses in
the pattern, so the amount of memory that is used before this
- limit acts varies from pattern to pattern. This limit is of
+ limit acts varies from pattern to pattern. This limit is of
use only if it is set smaller than --match-limit.
- There are no short forms for these options. The default lim-
- its can be set when the PCRE2 library is compiled; if they
- are not specified, the defaults are very large and so effec-
+ There are no short forms for these options. The default lim-
+ its can be set when the PCRE2 library is compiled; if they
+ are not specified, the defaults are very large and so effec-
tively unlimited.
--max-buffer-size=number
- This limits the expansion of the processing buffer, whose
- initial size can be set by --buffer-size. The maximum buffer
- size is silently forced to be no smaller than the starting
+ This limits the expansion of the processing buffer, whose
+ initial size can be set by --buffer-size. The maximum buffer
+ size is silently forced to be no smaller than the starting
buffer size.
-M, --multiline
- Allow patterns to match more than one line. When this option
+ Allow patterns to match more than one line. When this option
is set, the PCRE2 library is called in "multiline" mode. This
- allows a matched string to extend past the end of a line and
- continue on one or more subsequent lines. Patterns used with
+ allows a matched string to extend past the end of a line and
+ continue on one or more subsequent lines. Patterns used with
-M may usefully contain literal newline characters and inter-
- nal occurrences of ^ and $ characters. The output for a suc-
- cessful match may consist of more than one line. The first
- line is the line in which the match started, and the last
- line is the line in which the match ended. If the matched
- string ends with a newline sequence, the output ends at the
- end of that line. If -v is set, none of the lines in a
- multi-line match are output. Once a match has been handled,
- scanning restarts at the beginning of the line after the one
+ nal occurrences of ^ and $ characters. The output for a suc-
+ cessful match may consist of more than one line. The first
+ line is the line in which the match started, and the last
+ line is the line in which the match ended. If the matched
+ string ends with a newline sequence, the output ends at the
+ end of that line. If -v is set, none of the lines in a
+ multi-line match are output. Once a match has been handled,
+ scanning restarts at the beginning of the line after the one
in which the match ended.
- The newline sequence that separates multiple lines must be
- matched as part of the pattern. For example, to find the
- phrase "regular expression" in a file where "regular" might
- be at the end of a line and "expression" at the start of the
+ The newline sequence that separates multiple lines must be
+ matched as part of the pattern. For example, to find the
+ phrase "regular expression" in a file where "regular" might
+ be at the end of a line and "expression" at the start of the
next line, you could use this command:
pcre2grep -M 'regular\s+expression' <file>
- The \s escape sequence matches any white space character,
- including newlines, and is followed by + so as to match
- trailing white space on the first line as well as possibly
- handling a two-character newline sequence.
+ The \s escape sequence matches any white space character, in-
+ cluding newlines, and is followed by + so as to match trail-
+ ing white space on the first line as well as possibly han-
+ dling a two-character newline sequence.
- There is a limit to the number of lines that can be matched,
- imposed by the way that pcre2grep buffers the input file as
- it scans it. With a sufficiently large processing buffer,
+ There is a limit to the number of lines that can be matched,
+ imposed by the way that pcre2grep buffers the input file as
+ it scans it. With a sufficiently large processing buffer,
this should not be a problem, but the -M option does not work
when input is read line by line (see --line-buffered.)
-N newline-type, --newline=newline-type
- The PCRE2 library supports five different conventions for
- indicating the ends of lines. They are the single-character
- sequences CR (carriage return) and LF (linefeed), the two-
- character sequence CRLF, an "anycrlf" convention, which rec-
- ognizes any of the preceding three types, and an "any" con-
- vention, in which any Unicode line ending sequence is assumed
- to end a line. The Unicode sequences are the three just men-
- tioned, plus VT (vertical tab, U+000B), FF (form feed,
- U+000C), NEL (next line, U+0085), LS (line separator,
+ The PCRE2 library supports five different conventions for in-
+ dicating the ends of lines. They are the single-character se-
+ quences CR (carriage return) and LF (linefeed), the two-char-
+ acter sequence CRLF, an "anycrlf" convention, which recog-
+ nizes any of the preceding three types, and an "any" conven-
+ tion, in which any Unicode line ending sequence is assumed to
+ end a line. The Unicode sequences are the three just men-
+ tioned, plus VT (vertical tab, U+000B), FF (form feed,
+ U+000C), NEL (next line, U+0085), LS (line separator,
U+2028), and PS (paragraph separator, U+2029).
- When the PCRE2 library is built, a default line-ending
- sequence is specified. This is normally the standard
- sequence for the operating system. Unless otherwise specified
- by this option, pcre2grep uses the library's default. The
- possible values for this option are CR, LF, CRLF, ANYCRLF, or
- ANY. This makes it possible to use pcre2grep to scan files
- that have come from other environments without having to mod-
- ify their line endings. If the data that is being scanned
- does not agree with the convention set by this option,
- pcre2grep may behave in strange ways. Note that this option
- does not apply to files specified by the -f, --exclude-from,
- or --include-from options, which are expected to use the
- operating system's standard newline sequence.
+ When the PCRE2 library is built, a default line-ending se-
+ quence is specified. This is normally the standard sequence
+ for the operating system. Unless otherwise specified by this
+ option, pcre2grep uses the library's default. The possible
+ values for this option are CR, LF, CRLF, ANYCRLF, or ANY.
+ This makes it possible to use pcre2grep to scan files that
+ have come from other environments without having to modify
+ their line endings. If the data that is being scanned does
+ not agree with the convention set by this option, pcre2grep
+ may behave in strange ways. Note that this option does not
+ apply to files specified by the -f, --exclude-from, or --in-
+ clude-from options, which are expected to use the operating
+ system's standard newline sequence.
-n, --line-number
Precede each output line by its line number in the file, fol-
- lowed by a colon for matching lines or a hyphen for context
+ lowed by a colon for matching lines or a hyphen for context
lines. If the file name is also being output, it precedes the
- line number. When the -M option causes a pattern to match
- more than one line, only the first is preceded by its line
+ line number. When the -M option causes a pattern to match
+ more than one line, only the first is preceded by its line
number. This option is forced if --line-offsets is used.
- --no-jit If the PCRE2 library is built with support for just-in-time
+ --no-jit If the PCRE2 library is built with support for just-in-time
compiling (which speeds up matching), pcre2grep automatically
makes use of this, unless it was explicitly disabled at build
- time. This option can be used to disable the use of JIT at
- run time. It is provided for testing and working round prob-
+ time. This option can be used to disable the use of JIT at
+ run time. It is provided for testing and working round prob-
lems. It should never be needed in normal use.
-O text, --output=text
- When there is a match, instead of outputting the whole line
- that matched, output just the given text. This option is
- mutually exclusive with --only-matching, --file-offsets, and
+ When there is a match, instead of outputting the whole line
+ that matched, output just the given text. This option is mu-
+ tually exclusive with --only-matching, --file-offsets, and
--line-offsets. Escape sequences starting with a dollar char-
- acter may be used to insert the contents of the matched part
+ acter may be used to insert the contents of the matched part
of the line and/or captured substrings into the text.
- $<digits> or ${<digits>} is replaced by the captured sub-
- string of the given decimal number; zero substitutes the
+ $<digits> or ${<digits>} is replaced by the captured sub-
+ string of the given decimal number; zero substitutes the
whole match. If the number is greater than the number of cap-
- turing substrings, or if the capture is unset, the replace-
+ turing substrings, or if the capture is unset, the replace-
ment is empty.
- $a is replaced by bell; $b by backspace; $e by escape; $f by
- form feed; $n by newline; $r by carriage return; $t by tab;
+ $a is replaced by bell; $b by backspace; $e by escape; $f by
+ form feed; $n by newline; $r by carriage return; $t by tab;
$v by vertical tab.
- $o<digits> is replaced by the character represented by the
+ $o<digits> is replaced by the character represented by the
given octal number; up to three digits are processed.
- $x<digits> is replaced by the character represented by the
+ $x<digits> is replaced by the character represented by the
given hexadecimal number; up to two digits are processed.
- Any other character is substituted by itself. In particular,
+ Any other character is substituted by itself. In particular,
$$ is replaced by a single dollar.
-o, --only-matching
Show only the part of the line that matched a pattern instead
- of the whole line. In this mode, no context is shown. That
- is, the -A, -B, and -C options are ignored. If there is more
- than one match in a line, each of them is shown separately,
- on a separate line of output. If -o is combined with -v
- (invert the sense of the match to find non-matching lines),
- no output is generated, but the return code is set appropri-
- ately. If the matched portion of the line is empty, nothing
- is output unless the file name or line number are being
- printed, in which case they are shown on an otherwise empty
+ of the whole line. In this mode, no context is shown. That
+ is, the -A, -B, and -C options are ignored. If there is more
+ than one match in a line, each of them is shown separately,
+ on a separate line of output. If -o is combined with -v (in-
+ vert the sense of the match to find non-matching lines), no
+ output is generated, but the return code is set appropri-
+ ately. If the matched portion of the line is empty, nothing
+ is output unless the file name or line number are being
+ printed, in which case they are shown on an otherwise empty
line. This option is mutually exclusive with --output,
--file-offsets and --line-offsets.
-onumber, --only-matching=number
- Show only the part of the line that matched the capturing
+ Show only the part of the line that matched the capturing
parentheses of the given number. Up to 50 capturing parenthe-
- ses are supported by default. This limit can be changed via
- the --om-capture option. A pattern may contain any number of
- capturing parentheses, but only those whose number is within
- the limit can be accessed by -o. An error occurs if the num-
+ ses are supported by default. This limit can be changed via
+ the --om-capture option. A pattern may contain any number of
+ capturing parentheses, but only those whose number is within
+ the limit can be accessed by -o. An error occurs if the num-
ber specified by -o is greater than the limit.
-o0 is the same as -o without a number. Because these options
- can be given without an argument (see above), if an argument
- is present, it must be given in the same shell item, for
- example, -o3 or --only-matching=2. The comments given for the
- non-argument case above also apply to this option. If the
- specified capturing parentheses do not exist in the pattern,
- or were not set in the match, nothing is output unless the
+ can be given without an argument (see above), if an argument
+ is present, it must be given in the same shell item, for ex-
+ ample, -o3 or --only-matching=2. The comments given for the
+ non-argument case above also apply to this option. If the
+ specified capturing parentheses do not exist in the pattern,
+ or were not set in the match, nothing is output unless the
file name or line number are being output.
- If this option is given multiple times, multiple substrings
- are output for each match, in the order the options are
- given, and all on one line. For example, -o3 -o1 -o3 causes
- the substrings matched by capturing parentheses 3 and 1 and
- then 3 again to be output. By default, there is no separator
+ If this option is given multiple times, multiple substrings
+ are output for each match, in the order the options are
+ given, and all on one line. For example, -o3 -o1 -o3 causes
+ the substrings matched by capturing parentheses 3 and 1 and
+ then 3 again to be output. By default, there is no separator
(but see the next but one option).
--om-capture=number
- Set the number of capturing parentheses that can be accessed
+ Set the number of capturing parentheses that can be accessed
by -o. The default is 50.
--om-separator=text
- Specify a separating string for multiple occurrences of -o.
- The default is an empty string. Separating strings are never
+ Specify a separating string for multiple occurrences of -o.
+ The default is an empty string. Separating strings are never
coloured.
-q, --quiet
Work quietly, that is, display nothing except error messages.
- The exit status indicates whether or not any matches were
+ The exit status indicates whether or not any matches were
found.
-r, --recursive
- If any given path is a directory, recursively scan the files
- it contains, taking note of any --include and --exclude set-
- tings. By default, a directory is read as a normal file; in
- some operating systems this gives an immediate end-of-file.
- This option is a shorthand for setting the -d option to
- "recurse".
+ If any given path is a directory, recursively scan the files
+ it contains, taking note of any --include and --exclude set-
+ tings. By default, a directory is read as a normal file; in
+ some operating systems this gives an immediate end-of-file.
+ This option is a shorthand for setting the -d option to "re-
+ curse".
--recursion-limit=number
See --match-limit above.
-s, --no-messages
- Suppress error messages about non-existent or unreadable
- files. Such files are quietly skipped. However, the return
+ Suppress error messages about non-existent or unreadable
+ files. Such files are quietly skipped. However, the return
code is still 2, even if matches were found in other files.
-t, --total-count
- This option is useful when scanning more than one file. If
- used on its own, -t suppresses all output except for a grand
- total number of matching lines (or non-matching lines if -v
- is used) in all the files. If -t is used with -c, a grand
- total is output except when the previous output is just one
- line. In other words, it is not output when just one file's
- count is listed. If file names are being output, the grand
- total is preceded by "TOTAL:". Otherwise, it appears as just
- another number. The -t option is ignored when used with -L
- (list files without matches), because the grand total would
+ This option is useful when scanning more than one file. If
+ used on its own, -t suppresses all output except for a grand
+ total number of matching lines (or non-matching lines if -v
+ is used) in all the files. If -t is used with -c, a grand to-
+ tal is output except when the previous output is just one
+ line. In other words, it is not output when just one file's
+ count is listed. If file names are being output, the grand
+ total is preceded by "TOTAL:". Otherwise, it appears as just
+ another number. The -t option is ignored when used with -L
+ (list files without matches), because the grand total would
always be zero.
-u, --utf Operate in UTF-8 mode. This option is available only if PCRE2
has been compiled with UTF-8 support. All patterns (including
- those for any --exclude and --include options) and all sub-
- ject lines that are scanned must be valid strings of UTF-8
+ those for any --exclude and --include options) and all sub-
+ ject lines that are scanned must be valid strings of UTF-8
characters.
-U, --utf-allow-invalid
- As --utf, but in addition subject lines may contain invalid
- UTF-8 code unit sequences. These can never form part of any
+ As --utf, but in addition subject lines may contain invalid
+ UTF-8 code unit sequences. These can never form part of any
pattern match. This facility allows valid UTF-8 strings to be
sought in executable or other binary files. For more details
- about matching in non-valid UTF-8 strings, see the pcre2uni-
+ about matching in non-valid UTF-8 strings, see the pcre2uni-
code(3) documentation.
-V, --version
- Write the version numbers of pcre2grep and the PCRE2 library
- to the standard output and then exit. Anything else on the
+ Write the version numbers of pcre2grep and the PCRE2 library
+ to the standard output and then exit. Anything else on the
command line is ignored.
-v, --invert-match
- Invert the sense of the match, so that lines which do not
+ Invert the sense of the match, so that lines which do not
match any of the patterns are the ones that are found.
-w, --word-regex, --word-regexp
Force the patterns only to match "words". That is, there must
- be a word boundary at the start and end of each matched
- string. This is equivalent to having "\b(?:" at the start of
- each pattern, and ")\b" at the end. This option applies only
- to the patterns that are matched against the contents of
- files; it does not apply to patterns specified by any of the
+ be a word boundary at the start and end of each matched
+ string. This is equivalent to having "\b(?:" at the start of
+ each pattern, and ")\b" at the end. This option applies only
+ to the patterns that are matched against the contents of
+ files; it does not apply to patterns specified by any of the
--include or --exclude options.
-x, --line-regex, --line-regexp
- Force the patterns to start matching only at the beginnings
- of lines, and in addition, require them to match entire
+ Force the patterns to start matching only at the beginnings
+ of lines, and in addition, require them to match entire
lines. In multiline mode the match may be more than one line.
This is equivalent to having "^(?:" at the start of each pat-
- tern and ")$" at the end. This option applies only to the
- patterns that are matched against the contents of files; it
- does not apply to patterns specified by any of the --include
+ tern and ")$" at the end. This option applies only to the
+ patterns that are matched against the contents of files; it
+ does not apply to patterns specified by any of the --include
or --exclude options.
ENVIRONMENT VARIABLES
- The environment variables LC_ALL and LC_CTYPE are examined, in that
- order, for a locale. The first one that is set is used. This can be
- overridden by the --locale option. If no locale is set, the PCRE2
- library's default (usually the "C" locale) is used.
+ The environment variables LC_ALL and LC_CTYPE are examined, in that or-
+ der, for a locale. The first one that is set is used. This can be over-
+ ridden by the --locale option. If no locale is set, the PCRE2 library's
+ default (usually the "C" locale) is used.
NEWLINES
@@ -783,14 +782,14 @@
The -N (--newline) option allows pcre2grep to scan files with different
newline conventions from the default. Any parts of the input files that
- are written to the standard output are copied identically, with what-
- ever newline sequences they have in the input. However, the setting of
- this option affects only the way scanned files are processed. It does
- not affect the interpretation of files specified by the -f, --file-
+ are written to the standard output are copied identically, with what-
+ ever newline sequences they have in the input. However, the setting of
+ this option affects only the way scanned files are processed. It does
+ not affect the interpretation of files specified by the -f, --file-
list, --exclude-from, or --include-from options, nor does it affect the
- way in which pcre2grep writes informational messages to the standard
+ way in which pcre2grep writes informational messages to the standard
error and output streams. For these it uses the string "\n" to indicate
- newlines, relying on the C I/O library to convert this to an appropri-
+ newlines, relying on the C I/O library to convert this to an appropri-
ate sequence.
@@ -797,18 +796,18 @@
OPTIONS COMPATIBILITY
Many of the short and long forms of pcre2grep's options are the same as
- in the GNU grep program. Any long option of the form --xxx-regexp (GNU
+ in the GNU grep program. Any long option of the form --xxx-regexp (GNU
terminology) is also available as --xxx-regex (PCRE2 terminology). How-
- ever, the --depth-limit, --file-list, --file-offsets, --heap-limit,
- --include-dir, --line-offsets, --locale, --match-limit, -M, --multi-
- line, -N, --newline, --om-separator, --output, -u, --utf, -U, and
+ ever, the --depth-limit, --file-list, --file-offsets, --heap-limit,
+ --include-dir, --line-offsets, --locale, --match-limit, -M, --multi-
+ line, -N, --newline, --om-separator, --output, -u, --utf, -U, and
--utf-allow-invalid options are specific to pcre2grep, as is the use of
the --only-matching option with a capturing parentheses number.
- Although most of the common options work the same way, a few are dif-
- ferent in pcre2grep. For example, the --include option's argument is a
- glob for GNU grep, but a regular expression for pcre2grep. If both the
- -c and -l options are given, GNU grep lists only file names, without
+ Although most of the common options work the same way, a few are dif-
+ ferent in pcre2grep. For example, the --include option's argument is a
+ glob for GNU grep, but a regular expression for pcre2grep. If both the
+ -c and -l options are given, GNU grep lists only file names, without
counts, but pcre2grep gives the counts as well.
@@ -815,7 +814,7 @@
OPTIONS WITH DATA
There are four different ways in which an option with data can be spec-
- ified. If a short form option is used, the data may follow immedi-
+ ified. If a short form option is used, the data may follow immedi-
ately, or (with one exception) in the next command line item. For exam-
ple:
@@ -822,69 +821,69 @@
-f/some/file
-f /some/file
- The exception is the -o option, which may appear with or without data.
- Because of this, if data is present, it must follow immediately in the
+ The exception is the -o option, which may appear with or without data.
+ Because of this, if data is present, it must follow immediately in the
same item, for example -o3.
- If a long form option is used, the data may appear in the same command
- line item, separated by an equals character, or (with two exceptions)
+ If a long form option is used, the data may appear in the same command
+ line item, separated by an equals character, or (with two exceptions)
it may appear in the next command line item. For example:
--file=/some/file
--file /some/file
- Note, however, that if you want to supply a file name beginning with ~
- as data in a shell command, and have the shell expand ~ to a home
- directory, you must separate the file name from the option, because the
+ Note, however, that if you want to supply a file name beginning with ~
+ as data in a shell command, and have the shell expand ~ to a home di-
+ rectory, you must separate the file name from the option, because the
shell does not treat ~ specially unless it is at the start of an item.
- The exceptions to the above are the --colour (or --color) and --only-
- matching options, for which the data is optional. If one of these
- options does have data, it must be given in the first form, using an
+ The exceptions to the above are the --colour (or --color) and --only-
+ matching options, for which the data is optional. If one of these op-
+ tions does have data, it must be given in the first form, using an
equals character. Otherwise pcre2grep will assume that it has no data.
USING PCRE2'S CALLOUT FACILITY
- pcre2grep has, by default, support for calling external programs or
- scripts or echoing specific strings during matching by making use of
- PCRE2's callout facility. However, this support can be completely or
- partially disabled when pcre2grep is built. You can find out whether
- your binary has support for callouts by running it with the --help
- option. If callout support is completely disabled, all callouts in pat-
+ pcre2grep has, by default, support for calling external programs or
+ scripts or echoing specific strings during matching by making use of
+ PCRE2's callout facility. However, this support can be completely or
+ partially disabled when pcre2grep is built. You can find out whether
+ your binary has support for callouts by running it with the --help op-
+ tion. If callout support is completely disabled, all callouts in pat-
terns are ignored by pcre2grep. If the facility is partially disabled,
- calling external programs is not supported, and callouts that request
+ calling external programs is not supported, and callouts that request
it are ignored.
- A callout in a PCRE2 pattern is of the form (?C<arg>) where the argu-
- ment is either a number or a quoted string (see the pcre2callout docu-
- mentation for details). Numbered callouts are ignored by pcre2grep;
+ A callout in a PCRE2 pattern is of the form (?C<arg>) where the argu-
+ ment is either a number or a quoted string (see the pcre2callout docu-
+ mentation for details). Numbered callouts are ignored by pcre2grep;
only callouts with string arguments are useful.
Calling external programs or scripts
This facility can be independently disabled when pcre2grep is built. It
- is supported for Windows, where a call to _spawnvp() is used, for VMS,
- where lib$spawn() is used, and for any other Unix-like environment
+ is supported for Windows, where a call to _spawnvp() is used, for VMS,
+ where lib$spawn() is used, and for any other Unix-like environment
where fork() and execv() are available.
If the callout string does not start with a pipe (vertical bar) charac-
- ter, it is parsed into a list of substrings separated by pipe charac-
- ters. The first substring must be an executable name, with the follow-
+ ter, it is parsed into a list of substrings separated by pipe charac-
+ ters. The first substring must be an executable name, with the follow-
ing substrings specifying arguments:
executable_name|arg1|arg2|...
- Any substring (including the executable name) may contain escape
- sequences started by a dollar character: $<digits> or ${<digits>} is
- replaced by the captured substring of the given decimal number, which
- must be greater than zero. If the number is greater than the number of
- capturing substrings, or if the capture is unset, the replacement is
+ Any substring (including the executable name) may contain escape se-
+ quences started by a dollar character: $<digits> or ${<digits>} is re-
+ placed by the captured substring of the given decimal number, which
+ must be greater than zero. If the number is greater than the number of
+ capturing substrings, or if the capture is unset, the replacement is
empty.
- Any other character is substituted by itself. In particular, $$ is
- replaced by a single dollar and $| is replaced by a pipe character.
- Here is an example:
+ Any other character is substituted by itself. In particular, $$ is re-
+ placed by a single dollar and $| is replaced by a pipe character. Here
+ is an example:
echo -e "abcde\n12345" | pcre2grep \
'(?x)(.)(..(.))
@@ -897,13 +896,13 @@
Arg1: [1] [234] [4] Arg2: |1| ()
12345
- The parameters for the system call that is used to run the program or
+ The parameters for the system call that is used to run the program or
script are zero-terminated strings. This means that binary zero charac-
- ters in the callout argument will cause premature termination of their
- substrings, and therefore should not be present. Any syntax errors in
- the string (for example, a dollar not followed by another character)
- cause the callout to be ignored. If running the program fails for any
- reason (including the non-existence of the executable), a local match-
+ ters in the callout argument will cause premature termination of their
+ substrings, and therefore should not be present. Any syntax errors in
+ the string (for example, a dollar not followed by another character)
+ cause the callout to be ignored. If running the program fails for any
+ reason (including the non-existence of the executable), a local match-
ing failure occurs and the matcher backtracks in the normal way.
Echoing a specific string
@@ -912,28 +911,28 @@
pletely disabled when pcre2grep was built. If the callout string starts
with a pipe (vertical bar) character, the rest of the string is written
to the output, having been passed through the same escape processing as
- text from the --output option. This provides a simple echoing facility
- that avoids calling an external program or script. No terminator is
- added to the string, so if you want a newline, you must include it
- explicitly. Matching continues normally after the string is output. If
- you want to see only the callout output but not any output from an
- actual match, you should end the relevant pattern with (*FAIL).
+ text from the --output option. This provides a simple echoing facility
+ that avoids calling an external program or script. No terminator is
+ added to the string, so if you want a newline, you must include it ex-
+ plicitly. Matching continues normally after the string is output. If
+ you want to see only the callout output but not any output from an ac-
+ tual match, you should end the relevant pattern with (*FAIL).
MATCHING ERRORS
- It is possible to supply a regular expression that takes a very long
- time to fail to match certain lines. Such patterns normally involve
- nested indefinite repeats, for example: (a+)*\d when matched against a
- line of a's with no final digit. The PCRE2 matching function has a
- resource limit that causes it to abort in these circumstances. If this
- happens, pcre2grep outputs an error message and the line that caused
- the problem to the standard error stream. If there are more than 20
+ It is possible to supply a regular expression that takes a very long
+ time to fail to match certain lines. Such patterns normally involve
+ nested indefinite repeats, for example: (a+)*\d when matched against a
+ line of a's with no final digit. The PCRE2 matching function has a re-
+ source limit that causes it to abort in these circumstances. If this
+ happens, pcre2grep outputs an error message and the line that caused
+ the problem to the standard error stream. If there are more than 20
such errors, pcre2grep gives up.
- The --match-limit option of pcre2grep can be used to set the overall
- resource limit. There are also other limits that affect the amount of
- memory used during matching; see the discussion of --heap-limit and
+ The --match-limit option of pcre2grep can be used to set the overall
+ resource limit. There are also other limits that affect the amount of
+ memory used during matching; see the discussion of --heap-limit and
--depth-limit above.
@@ -940,13 +939,13 @@
DIAGNOSTICS
Exit status is 0 if any matches were found, 1 if no matches were found,
- and 2 for syntax errors, overlong lines, non-existent or inaccessible
- files (even if matches were found in other files) or too many matching
+ and 2 for syntax errors, overlong lines, non-existent or inaccessible
+ files (even if matches were found in other files) or too many matching
errors. Using the -s option to suppress error messages about inaccessi-
ble files does not affect the return code.
- When run under VMS, the return code is placed in the symbol
- PCRE2GREP_RC because VMS does not distinguish between exit(0) and
+ When run under VMS, the return code is placed in the symbol
+ PCRE2GREP_RC because VMS does not distinguish between exit(0) and
exit(1).
Modified: code/trunk/doc/pcre2pattern.3
===================================================================
--- code/trunk/doc/pcre2pattern.3 2019-06-21 16:10:17 UTC (rev 1117)
+++ code/trunk/doc/pcre2pattern.3 2019-06-22 16:36:15 UTC (rev 1118)
@@ -1,4 +1,4 @@
-.TH PCRE2PATTERN 3 "21 June 2019" "PCRE2 10.34"
+.TH PCRE2PATTERN 3 "22 June 2019" "PCRE2 10.34"
.SH NAME
PCRE2 - Perl-compatible regular expressions (revised API)
.SH "PCRE2 REGULAR EXPRESSION DETAILS"
@@ -3564,9 +3564,10 @@
first match attempt, the second attempt would start at the second character
instead of skipping on to "c".
.P
-If (*SKIP) is used inside a lookbehind to specify a new starting position that
-is not later than the starting point of the current match, the position
-specified by (*SKIP) is ignored, and instead the normal "bumpalong" occurs.
+If (*SKIP) is used to specify a new starting position that is the same as the
+starting position of the current match, or (by being inside a lookbehind)
+earlier, the position specified by (*SKIP) is ignored, and instead the normal
+"bumpalong" occurs.
.sp
(*SKIP:NAME)
.sp
@@ -3787,6 +3788,6 @@
.rs
.sp
.nf
-Last updated: 21 June 2019
+Last updated: 22 June 2019
Copyright (c) 1997-2019 University of Cambridge.
.fi
Modified: code/trunk/doc/pcre2test.txt
===================================================================
--- code/trunk/doc/pcre2test.txt 2019-06-21 16:10:17 UTC (rev 1117)
+++ code/trunk/doc/pcre2test.txt 2019-06-22 16:36:15 UTC (rev 1118)
@@ -13,8 +13,8 @@
but it can also be used for experimenting with regular expressions.
This document describes the features of the test program; for details
of the regular expressions themselves, see the pcre2pattern documenta-
- tion. For details of the PCRE2 library function calls and their
- options, see the pcre2api documentation.
+ tion. For details of the PCRE2 library function calls and their op-
+ tions, see the pcre2api documentation.
The input for pcre2test is a sequence of regular expression patterns
and subject strings to be matched. There are also command lines for
@@ -33,8 +33,8 @@
which are specifically designed for use in conjunction with the test
script and data files that are distributed as part of PCRE2. All the
modifiers are documented here, some without much justification, but
- many of them are unlikely to be of use except when testing the
- libraries.
+ many of them are unlikely to be of use except when testing the li-
+ braries.
PCRE2's 8-BIT, 16-BIT AND 32-BIT LIBRARIES
@@ -41,18 +41,18 @@
Different versions of the PCRE2 library can be built to support charac-
ter strings that are encoded in 8-bit, 16-bit, or 32-bit code units.
- One, two, or all three of these libraries may be simultaneously
- installed. The pcre2test program can be used to test all the libraries.
+ One, two, or all three of these libraries may be simultaneously in-
+ stalled. The pcre2test program can be used to test all the libraries.
However, its own input and output are always in 8-bit format. When
testing the 16-bit or 32-bit libraries, patterns and subject strings
- are converted to 16-bit or 32-bit format before being passed to the
- library functions. Results are converted back to 8-bit code units for
+ are converted to 16-bit or 32-bit format before being passed to the li-
+ brary functions. Results are converted back to 8-bit code units for
output.
In the rest of this document, the names of library functions and struc-
- tures are given in generic form, for example, pcre_compile(). The
- actual names used in the libraries have a suffix _8, _16, or _32, as
- appropriate.
+ tures are given in generic form, for example, pcre_compile(). The ac-
+ tual names used in the libraries have a suffix _8, _16, or _32, as ap-
+ propriate.
INPUT ENCODING
@@ -70,8 +70,8 @@
processed for backslash escapes, which makes it possible to include any
data value in strings that are passed to the library for matching. For
patterns, there is a facility for specifying some or all of the 8-bit
- input characters as hexadecimal pairs, which makes it possible to
- include binary zeros.
+ input characters as hexadecimal pairs, which makes it possible to in-
+ clude binary zeros.
Input for the 16-bit and 32-bit libraries
@@ -78,10 +78,10 @@
When testing the 16-bit or 32-bit libraries, there is a need to be able
to generate character code points greater than 255 in the strings that
are passed to the library. For subject lines, backslash escapes can be
- used. In addition, when the utf modifier (see "Setting compilation
- options" below) is set, the pattern and any following subject lines are
- interpreted as UTF-8 strings and translated to UTF-16 or UTF-32 as
- appropriate.
+ used. In addition, when the utf modifier (see "Setting compilation op-
+ tions" below) is set, the pattern and any following subject lines are
+ interpreted as UTF-8 strings and translated to UTF-16 or UTF-32 as ap-
+ propriate.
For non-UTF testing of wide characters, the utf8_input modifier can be
used. This is mutually exclusive with utf, and is allowed only in
@@ -121,8 +121,8 @@
piled.
-AC As for -ac, but in addition behave as if each subject line
- has the callout_extra modifier, that is, show additional
- information from callouts.
+ has the callout_extra modifier, that is, show additional in-
+ formation from callouts.
-b Behave as if each pattern has the fullbincode modifier; the
full internal binary form of the pattern is output after com-
@@ -130,9 +130,9 @@
-C Output the version number of the PCRE2 library, and all
available information about the optional features that are
- included, and then exit with zero exit code. All other
- options are ignored. If both -C and -LM are present, which-
- ever is first is recognized.
+ included, and then exit with zero exit code. All other op-
+ tions are ignored. If both -C and -LM are present, whichever
+ is first is recognized.
-C option Output information about a specific build-time option, then
exit. This functionality is intended for use in scripts such
@@ -269,8 +269,8 @@
supply them explicitly.
An empty line or the end of the file signals the end of the subject
- lines for a test, at which point a new pattern or command line is
- expected if there is still input to be read.
+ lines for a test, at which point a new pattern or command line is ex-
+ pected if there is still input to be read.
COMMAND LINES
@@ -311,8 +311,8 @@
as indicating a newline in a pattern or subject string. The default can
be overridden when a pattern is compiled. The standard test files con-
tain tests of various newline conventions, but the majority of the
- tests expect a single linefeed to be recognized as a newline by
- default. Without special action the tests would fail when PCRE2 is com-
+ tests expect a single linefeed to be recognized as a newline by de-
+ fault. Without special action the tests would fail when PCRE2 is com-
piled with either CR or CRLF as the default newline.
The #newline_default command specifies a list of newline types that are
@@ -323,14 +323,14 @@
If the default newline is in the list, this command has no effect. Oth-
erwise, except when testing the POSIX API, a newline modifier that
- specifies the first newline convention in the list (LF in the above
- example) is added to any pattern that does not already have a newline
+ specifies the first newline convention in the list (LF in the above ex-
+ ample) is added to any pattern that does not already have a newline
modifier. If the newline list is empty, the feature is turned off. This
command is present in a number of the standard test input files.
- When the POSIX API is being tested there is no way to override the
- default newline convention, though it is possible to set the newline
- convention from within the pattern. A warning is given if the posix or
+ When the POSIX API is being tested there is no way to override the de-
+ fault newline convention, though it is possible to set the newline con-
+ vention from within the pattern. A warning is given if the posix or
posix_nosub modifier is used when #newline_default would set a default
for the non-POSIX API.
@@ -344,8 +344,8 @@
The appearance of this line causes all subsequent modifier settings to
be checked for compatibility with the perltest.sh script, which is used
to confirm that Perl gives the same results as PCRE2. Also, apart from
- comment lines, #pattern commands, and #subject commands that set or
- unset "mark", no command lines are permitted, because they and many of
+ comment lines, #pattern commands, and #subject commands that set or un-
+ set "mark", no command lines are permitted, because they and many of
the modifiers are specific to pcre2test, and should not be used in test
files that are also processed by perltest.sh. The #perltest command
helps detect tests that are accidentally put in the wrong file.
@@ -376,8 +376,8 @@
list are separated by commas followed by optional white space. Trailing
whitespace in a modifier list is ignored. Some modifiers may be given
for both patterns and subject lines, whereas others are valid only for
- one or the other. Each modifier has a long name, for example
- "anchored", and some of them must be followed by an equals sign and a
+ one or the other. Each modifier has a long name, for example "an-
+ chored", and some of them must be followed by an equals sign and a
value, for example, "offset=12". Values cannot contain comma charac-
ters, but may contain spaces. Modifiers that do not take values may be
preceded by a minus sign to turn off a previous setting.
@@ -498,8 +498,8 @@
\= This is a comment.
abc\= This is an invalid modifier list.
- A backslash followed by any other non-alphanumeric character just
- escapes that character. A backslash followed by anything else causes an
+ A backslash followed by any other non-alphanumeric character just es-
+ capes that character. A backslash followed by anything else causes an
error. However, if the very last character in the line is a backslash
(and there is no modifier list), it is ignored. This gives a way of
passing an empty line as data, since a real empty line terminates the
@@ -523,13 +523,13 @@
The following modifiers set options for pcre2_compile(). Most of them
set bits in the options argument of that function, but those whose
names start with PCRE2_EXTRA are additional options that are set in the
- compile context. For the main options, there are some single-letter
- abbreviations that are the same as Perl options. There is special han-
+ compile context. For the main options, there are some single-letter ab-
+ breviations that are the same as Perl options. There is special han-
dling for /x: if a second x is present, PCRE2_EXTENDED is converted
- into PCRE2_EXTENDED_MORE as in Perl. A third appearance adds
- PCRE2_EXTENDED as well, though this makes no difference to the way
- pcre2_compile() behaves. See pcre2api for a description of the effects
- of these options.
+ into PCRE2_EXTENDED_MORE as in Perl. A third appearance adds PCRE2_EX-
+ TENDED as well, though this makes no difference to the way pcre2_com-
+ pile() behaves. See pcre2api for a description of the effects of these
+ options.
allow_empty_class set PCRE2_ALLOW_EMPTY_CLASS
allow_surrogate_escapes set PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES
@@ -577,9 +577,9 @@
Setting compilation controls
- The following modifiers affect the compilation process or request
- information about the pattern. There are single-letter abbreviations
- for some that are heavily used in the test files.
+ The following modifiers affect the compilation process or request in-
+ formation about the pattern. There are single-letter abbreviations for
+ some that are heavily used in the test files.
bsr=[anycrlf|unicode] specify \R handling
/B bincode show binary code without lengths
@@ -717,8 +717,8 @@
minated strings but can be passed by length instead of being zero-ter-
minated. The use_length modifier causes this to happen. Using a length
happens automatically (whether or not use_length is set) when hex is
- set, because patterns specified in hexadecimal may contain binary
- zeros.
+ set, because patterns specified in hexadecimal may contain binary ze-
+ ros.
If hex or use_length is used with the POSIX wrapper API (see "Using the
POSIX wrapper API" below), the REG_PEND extension is used to pass the
@@ -770,8 +770,8 @@
partial modifier in "Subject Modifiers" below for details of how these
options are specified for each match attempt.
- JIT compilation is requested by the jit pattern modifier, which may
- optionally be followed by an equals sign and a number in the range 0 to
+ JIT compilation is requested by the jit pattern modifier, which may op-
+ tionally be followed by an equals sign and a number in the range 0 to
7. The three bits that make up the number specify which of the three
JIT operating modes are to be compiled:
@@ -799,8 +799,8 @@
none was compiled for non-partial matching.
If JIT compilation is successful, the compiled JIT code will automati-
- cally be used when an appropriate type of match is run, except when
- incompatible run-time options are specified. For more details, see the
+ cally be used when an appropriate type of match is run, except when in-
+ compatible run-time options are specified. For more details, see the
pcre2jit documentation. See also the jitstack modifier below for a way
of setting the size of the JIT stack.
@@ -847,8 +847,8 @@
Limiting nested parentheses
The parens_nest_limit modifier sets a limit on the depth of nested
- parentheses in a pattern. Breaching the limit causes a compilation
- error. The default for the library is set when PCRE2 is built, but
+ parentheses in a pattern. Breaching the limit causes a compilation er-
+ ror. The default for the library is set when PCRE2 is built, but
pcre2test sets its own default of 220, which is required for running
the standard test suite.
@@ -886,13 +886,13 @@
buffer is too small for the error message. If this modifier has not
been set, a large buffer is used.
- The aftertext and allaftertext subject modifiers work as described
- below. All other modifiers are either ignored, with a warning message,
- or cause an error.
+ The aftertext and allaftertext subject modifiers work as described be-
+ low. All other modifiers are either ignored, with a warning message, or
+ cause an error.
- The pattern is passed to regcomp() as a zero-terminated string by
- default, but if the use_length or hex modifiers are set, the REG_PEND
- extension is used to pass it by length.
+ The pattern is passed to regcomp() as a zero-terminated string by de-
+ fault, but if the use_length or hex modifiers are set, the REG_PEND ex-
+ tension is used to pass it by length.
Testing the stack guard feature
@@ -920,8 +920,8 @@
2 a set of tables defining ISO 8859 characters
In table 2, some characters whose codes are greater than 128 are iden-
- tified as letters, digits, spaces, etc. Setting alternate character
- tables and a locale are mutually exclusive.
+ tified as letters, digits, spaces, etc. Setting alternate character ta-
+ bles and a locale are mutually exclusive.
Setting certain match controls
@@ -971,12 +971,12 @@
terns" below. If pushcopy is used instead of push, a copy of the com-
piled pattern is stacked, leaving the original as current, ready to
match the following input lines. This provides a way of testing the
- pcre2_code_copy() function. The push and pushcopy modifiers are
- incompatible with compilation modifiers such as global that act at
- match time. Any that are specified are ignored (for the stacked copy),
- with a warning message, except for replace, which causes an error. Note
- that jitverify, which is allowed, does not carry through to any subse-
- quent matching that uses a stacked pattern.
+ pcre2_code_copy() function. The push and pushcopy modifiers are in-
+ compatible with compilation modifiers such as global that act at match
+ time. Any that are specified are ignored (for the stacked copy), with a
+ warning message, except for replace, which causes an error. Note that
+ jitverify, which is allowed, does not carry through to any subsequent
+ matching that uses a stacked pattern.
Testing foreign pattern conversion
@@ -1124,12 +1124,12 @@
The allusedtext modifier requests that all the text that was consulted
during a successful pattern match by the interpreter should be shown.
This feature is not supported for JIT matching, and if requested with
- JIT it is ignored (with a warning message). Setting this modifier
- affects the output if there is a lookbehind at the start of a match, or
- a lookahead at the end, or if \K is used in the pattern. Characters
- that precede or follow the start and end of the actual match are indi-
- cated in the output by '<' or '>' characters underneath them. Here is
- an example:
+ JIT it is ignored (with a warning message). Setting this modifier af-
+ fects the output if there is a lookbehind at the start of a match, or a
+ lookahead at the end, or if \K is used in the pattern. Characters that
+ precede or follow the start and end of the actual match are indicated
+ in the output by '<' or '>' characters underneath them. Here is an ex-
+ ample:
re> /(?<=pqr)abc(?=xyz)/
data> 123pqrabcxyz456\=allusedtext
@@ -1145,8 +1145,8 @@
string. The only time when this occurs is when \K has been processed as
part of the match. In this situation, the output for the matched string
is displayed from the starting character instead of from the match
- point, with circumflex characters under the earlier characters. For
- example:
+ point, with circumflex characters under the earlier characters. For ex-
+ ample:
re> /abc\Kxyz/
data> abcxyz\=startchar
@@ -1171,12 +1171,12 @@
The allvector modifier requests that the entire ovector be shown, what-
ever the outcome of the match. Compare allcaptures, which shows only up
to the maximum number of capture groups for the pattern, and then only
- for a successful complete non-DFA match. This modifier, which acts
- after any match result, and also for DFA matching, provides a means of
+ for a successful complete non-DFA match. This modifier, which acts af-
+ ter any match result, and also for DFA matching, provides a means of
checking that there are no unexpected modifications to ovector fields.
Before each match attempt, the ovector is filled with a special value,
- and if this is found in both elements of a capturing pair,
- "<unchanged>" is output. After a successful match, this applies to all
+ and if this is found in both elements of a capturing pair, "<un-
+ changed>" is output. After a successful match, this applies to all
groups after the maximum capture group for the pattern. In other cases
it applies to the entire ovector. After a partial match, the first two
elements are the only ones that should be set. After a DFA match, the
@@ -1207,12 +1207,12 @@
If an empty string is matched, the next match is done with the
PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED flags set, in order to search
for another, non-empty, match at the same point in the subject. If this
- match fails, the start offset is advanced, and the normal match is
- retried. This imitates the way Perl handles such cases when using the
- /g modifier or the split() function. Normally, the start offset is
- advanced by one character, but if the newline convention recognizes
- CRLF as a newline, and the current character is CR followed by LF, an
- advance of two characters occurs.
+ match fails, the start offset is advanced, and the normal match is re-
+ tried. This imitates the way Perl handles such cases when using the /g
+ modifier or the split() function. Normally, the start offset is ad-
+ vanced by one character, but if the newline convention recognizes CRLF
+ as a newline, and the current character is CR followed by LF, an ad-
+ vance of two characters occurs.
Testing substring extraction functions
@@ -1275,8 +1275,8 @@
than 256 characters) for substitution tests, as fixed-size buffers are
used. To make it easy to test for buffer overflow, if the replacement
string starts with a number in square brackets, that number is passed
- to pcre2_substitute() as the size of the output buffer, with the
- replacement string starting at the next character. Here is an example
+ to pcre2_substitute() as the size of the output buffer, with the re-
+ placement string starting at the next character. Here is an example
that tests the edge case:
/abc/
@@ -1285,10 +1285,10 @@
123abc123\=replace=[9]XYZ
Failed: error -47: no more memory
- The default action of pcre2_substitute() is to return
- PCRE2_ERROR_NOMEMORY when the output buffer is too small. However, if
- the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set (by using the sub-
- stitute_overflow_length modifier), pcre2_substitute() continues to go
+ The default action of pcre2_substitute() is to return PCRE2_ER-
+ ROR_NOMEMORY when the output buffer is too small. However, if the
+ PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set (by using the substi-
+ tute_overflow_length modifier), pcre2_substitute() continues to go
through the motions of matching and substituting (but not doing any
callouts), in order to compute the size of buffer that is required.
When this happens, pcre2test shows the required buffer length (which
@@ -1323,8 +1323,8 @@
Then are listed the offsets of the old substring, its contents, and the
same for the replacement.
- By default, the substitution callout function returns zero, which
- accepts the replacement and causes matching to continue if /g was used.
+ By default, the substitution callout function returns zero, which ac-
+ cepts the replacement and causes matching to continue if /g was used.
Two further modifiers can be used to test other return values. If sub-
stitute_skip is set to a value greater than zero the callout function
returns +1 for the match of that number, and similarly substitute_stop
@@ -1411,8 +1411,8 @@
The memory modifier causes pcre2test to log the sizes of all heap mem-
ory allocation and freeing calls that occur during a call to
- pcre2_match() or pcre2_dfa_match(). These occur only when a match
- requires a bigger vector than the default for remembering backtracking
+ pcre2_match() or pcre2_dfa_match(). These occur only when a match re-
+ quires a bigger vector than the default for remembering backtracking
points (pcre2_match()) or for internal workspace (pcre2_dfa_match()).
In many cases there will be no heap memory used and therefore no addi-
tional output. No heap memory is allocated during matching with JIT, so
@@ -1435,9 +1435,9 @@
Setting the size of the output vector
- The ovector modifier applies only to the subject line in which it
- appears, though of course it can also be used to set a default in a
- #subject command. It specifies the number of pairs of offsets that are
+ The ovector modifier applies only to the subject line in which it ap-
+ pears, though of course it can also be used to set a default in a #sub-
+ ject command. It specifies the number of pairs of offsets that are
available for storing matching information. The default is 15.
A value of zero is useful when testing the POSIX API because it causes
@@ -1491,12 +1491,12 @@
When a match succeeds, pcre2test outputs the list of captured sub-
strings, starting with number 0 for the string that matched the whole
- pattern. Otherwise, it outputs "No match" when the return is
- PCRE2_ERROR_NOMATCH, or "Partial match:" followed by the partially
- matching substring when the return is PCRE2_ERROR_PARTIAL. (Note that
- this is the entire substring that was inspected during the partial
- match; it may include characters before the actual match start if a
- lookbehind assertion, \K, \b, or \B was involved.)
+ pattern. Otherwise, it outputs "No match" when the return is PCRE2_ER-
+ ROR_NOMATCH, or "Partial match:" followed by the partially matching
+ substring when the return is PCRE2_ERROR_PARTIAL. (Note that this is
+ the entire substring that was inspected during the partial match; it
+ may include characters before the actual match start if a lookbehind
+ assertion, \K, \b, or \B was involved.)
For any other return, pcre2test outputs the PCRE2 negative error number
and a short descriptive phrase. If the error is a failed UTF string
@@ -1541,8 +1541,8 @@
0: cat
0+ aract
- If global matching is requested, the results of successive matching
- attempts are output in sequence, like this:
+ If global matching is requested, the results of successive matching at-
+ tempts are output in sequence, like this:
re> /\Bi(\w\w)/g
data> Mississippi
@@ -1580,12 +1580,12 @@
2: tan
Using the normal matching function on this data finds only "tang". The
- longest matching string is always given first (and numbered zero).
- After a PCRE2_ERROR_PARTIAL return, the output is "Partial match:",
- followed by the partially matching substring. Note that this is the
- entire substring that was inspected during the partial match; it may
- include characters before the actual match start if a lookbehind asser-
- tion, \b, or \B was involved. (\K is not supported for DFA matching.)
+ longest matching string is always given first (and numbered zero). Af-
+ ter a PCRE2_ERROR_PARTIAL return, the output is "Partial match:", fol-
+ lowed by the partially matching substring. Note that this is the entire
+ substring that was inspected during the partial match; it may include
+ characters before the actual match start if a lookbehind assertion, \b,
+ or \B was involved. (\K is not supported for DFA matching.)
If global matching is requested, the search for further matches resumes
at the end of the longest match. For example:
@@ -1638,12 +1638,12 @@
--->pqrabcdef
0 ^ ^ \d
- This output indicates that callout number 0 occurred for a match
- attempt starting at the fourth character of the subject string, when
- the pointer was at the seventh character, and when the next pattern
- item was \d. Just one circumflex is output if the start and current
- positions are the same, or if the current position precedes the start
- position, which can happen if the callout is in a lookbehind assertion.
+ This output indicates that callout number 0 occurred for a match at-
+ tempt starting at the fourth character of the subject string, when the
+ pointer was at the seventh character, and when the next pattern item
+ was \d. Just one circumflex is output if the start and current posi-
+ tions are the same, or if the current position precedes the start posi-
+ tion, which can happen if the callout is in a lookbehind assertion.
Callouts numbered 255 are assumed to be automatic callouts, inserted as
a result of the auto_callout pattern modifier. In this case, instead of
@@ -1660,8 +1660,8 @@
0: E*
If a pattern contains (*MARK) items, an additional line is output when-
- ever a change of latest mark is passed to the callout function. For
- example:
+ ever a change of latest mark is passed to the callout function. For ex-
+ ample:
re> /a(*MARK:X)bc/auto_callout
data> abc
@@ -1683,8 +1683,8 @@
The output for a callout with a string argument is similar, except that
instead of outputting a callout number before the position indicators,
- the callout string and its offset in the pattern string are output
- before the reflection of the subject string, and the subject string is
+ the callout string and its offset in the pattern string are output be-
+ fore the reflection of the subject string, and the subject string is
reflected for each callout. For example:
re> /^ab(?C'first')cd(?C"second")ef/
@@ -1800,9 +1800,9 @@
When pcre2test is outputting text that is a matched part of a subject
string, it behaves in the same way, unless a different locale has been
- set for the pattern (using the locale modifier). In this case, the
- isprint() function is used to distinguish printing and non-printing
- characters.
+ set for the pattern (using the locale modifier). In this case, the is-
+ print() function is used to distinguish printing and non-printing char-
+ acters.
SAVING AND RESTORING COMPILED PATTERNS
@@ -1814,14 +1814,14 @@
have the same endianness, pointer width and PCRE2_SIZE type. Before
compiled patterns can be saved they must be serialized, that is, con-
verted to a stream of bytes. A single byte stream may contain any num-
- ber of compiled patterns, but they must all use the same character
- tables. A single copy of the tables is included in the byte stream (its
+ ber of compiled patterns, but they must all use the same character ta-
+ bles. A single copy of the tables is included in the byte stream (its
size is 1088 bytes).
- The functions whose names begin with pcre2_serialize_ are used for
- serializing and de-serializing. They are described in the pcre2serial-
- ize documentation. In this section we describe the features of
- pcre2test that can be used to test these functions.
+ The functions whose names begin with pcre2_serialize_ are used for se-
+ rializing and de-serializing. They are described in the pcre2serialize
+ documentation. In this section we describe the features of pcre2test
+ that can be used to test these functions.
Note that "serialization" in PCRE2 does not convert compiled patterns
to an abstract format like Java or .NET. It just makes a reloadable
@@ -1831,8 +1831,8 @@
piled, it is pushed onto a stack of compiled patterns, and pcre2test
expects the next line to contain a new pattern (or command) instead of
a subject line. By contrast, the pushcopy modifier causes a copy of the
- compiled pattern to be stacked, leaving the original available for
- immediate matching. By using push and/or pushcopy, a number of patterns
+ compiled pattern to be stacked, leaving the original available for im-
+ mediate matching. By using push and/or pushcopy, a number of patterns
can be compiled and retained. These modifiers are incompatible with
posix, and control modifiers that act at match time are ignored (with a
message) for the stacked patterns. The jitverify modifier applies only
@@ -1855,8 +1855,8 @@
matched with the pattern, terminated as usual by an empty line or end
of file. This command may be followed by a modifier list containing
only control modifiers that act after a pattern has been compiled. In
- particular, hex, posix, posix_nosub, push, and pushcopy are not
- allowed, nor are any option-setting modifiers. The JIT modifiers are,
+ particular, hex, posix, posix_nosub, push, and pushcopy are not al-
+ lowed, nor are any option-setting modifiers. The JIT modifiers are,
however permitted. Here is an example that saves and reloads two pat-
terns.
