Revision: 414
http://www.exim.org/viewvc/pcre2?view=rev&revision=414
Author: ph10
Date: 2015-11-05 17:33:39 +0000 (Thu, 05 Nov 2015)
Log Message:
-----------
Implement pcre2_set_max_pattern_length()
Modified Paths:
--------------
code/trunk/ChangeLog
code/trunk/doc/html/index.html
code/trunk/doc/html/pcre2api.html
code/trunk/doc/html/pcre2limits.html
code/trunk/doc/html/pcre2pattern.html
code/trunk/doc/html/pcre2posix.html
code/trunk/doc/html/pcre2serialize.html
code/trunk/doc/html/pcre2test.html
code/trunk/doc/index.html.src
code/trunk/doc/pcre2.txt
code/trunk/doc/pcre2api.3
code/trunk/doc/pcre2limits.3
code/trunk/doc/pcre2test.1
code/trunk/doc/pcre2test.txt
code/trunk/src/pcre2.h
code/trunk/src/pcre2.h.in
code/trunk/src/pcre2_compile.c
code/trunk/src/pcre2_context.c
code/trunk/src/pcre2_error.c
code/trunk/src/pcre2_intmodedep.h
code/trunk/src/pcre2test.c
code/trunk/testdata/testinput2
code/trunk/testdata/testoutput2
Added Paths:
-----------
code/trunk/doc/html/pcre2_set_max_pattern_length.html
code/trunk/doc/pcre2_set_max_pattern_length.3
Modified: code/trunk/ChangeLog
===================================================================
--- code/trunk/ChangeLog 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/ChangeLog 2015-11-05 17:33:39 UTC (rev 414)
@@ -263,7 +263,10 @@
76. Check the length of subpattern names and the names in (*MARK:xx) etc.
dynamically to avoid the possibility of integer overflow.
+77. Implement pcre2_set_max_pattern_length() so that programs can restrict the
+size of patterns that they are prepared to handle.
+
Version 10.20 30-June-2015
--------------------------
Modified: code/trunk/doc/html/index.html
===================================================================
--- code/trunk/doc/html/index.html 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/html/index.html 2015-11-05 17:33:39 UTC (rev 414)
@@ -210,12 +210,15 @@
<tr><td><a href="pcre2_set_match_limit.html">pcre2_set_match_limit</a></td>
<td> Set the match limit</td></tr>
-<tr><td><a href="pcre2_set_offset_limit.html">pcre2_set_offset_limit</a></td>
- <td> Set the offset limit</td></tr>
+<tr><td><a href="pcre2_set_max_pattern_length.html">pcre2_set_max_pattern_length</a></td>
+ <td> Set the maximum length of pattern</td></tr>
<tr><td><a href="pcre2_set_newline.html">pcre2_set_newline</a></td>
<td> Set the newline convention</td></tr>
+<tr><td><a href="pcre2_set_offset_limit.html">pcre2_set_offset_limit</a></td>
+ <td> Set the offset limit</td></tr>
+
<tr><td><a href="pcre2_set_parens_nest_limit.html">pcre2_set_parens_nest_limit</a></td>
<td> Set the parentheses nesting limit</td></tr>
Added: code/trunk/doc/html/pcre2_set_max_pattern_length.html
===================================================================
--- code/trunk/doc/html/pcre2_set_max_pattern_length.html (rev 0)
+++ code/trunk/doc/html/pcre2_set_max_pattern_length.html 2015-11-05 17:33:39 UTC (rev 414)
@@ -0,0 +1,40 @@
+<html>
+<head>
+<title>pcre2_set_max_pattern_length specification</title>
+</head>
+<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
+<h1>pcre2_set_max_pattern_length man page</h1>
+<p>
+Return to the <a href="index.html">PCRE2 index page</a>.
+</p>
+<p>
+This page is part of the PCRE2 HTML documentation. It was generated
+automatically from the original man page. If there is any nonsense in it,
+please consult the man page, in case the conversion went wrong.
+<br>
+<br><b>
+SYNOPSIS
+</b><br>
+<P>
+<b>#include <pcre2.h></b>
+</P>
+<P>
+<b>int pcre2_set_max_pattern_length(pcre2_compile_context *<i>ccontext</i>,</b>
+<b> PCRE2_SIZE <i>value</i>);</b>
+</P>
+<br><b>
+DESCRIPTION
+</b><br>
+<P>
+This function sets, in a compile context, the maximum length (in code units) of
+the pattern that can be compiled. The result is always zero.
+</P>
+<P>
+There is a complete description of the PCRE2 native API in the
+<a href="pcre2api.html"><b>pcre2api</b></a>
+page and a description of the POSIX API in the
+<a href="pcre2posix.html"><b>pcre2posix</b></a>
+page.
+<p>
+Return to the <a href="index.html">PCRE2 index page</a>.
+</p>
Modified: code/trunk/doc/html/pcre2api.html
===================================================================
--- code/trunk/doc/html/pcre2api.html 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/html/pcre2api.html 2015-11-05 17:33:39 UTC (rev 414)
@@ -143,6 +143,10 @@
<b> const unsigned char *<i>tables</i>);</b>
<br>
<br>
+<b>int pcre2_set_max_pattern_length(pcre2_compile_context *<i>ccontext</i>,</b>
+<b> PCRE2_SIZE <i>value</i>);</b>
+<br>
+<br>
<b>int pcre2_set_newline(pcre2_compile_context *<i>ccontext</i>,</b>
<b> uint32_t <i>value</i>);</b>
<br>
@@ -614,6 +618,7 @@
PCRE2's character tables
The newline character sequence
The compile time nested parentheses limit
+ The maximum length of the pattern string
An external function for stack checking
</pre>
A compile context is also required if you are using custom memory management.
@@ -652,6 +657,15 @@
The value must be the result of a call to <i>pcre2_maketables()</i>, whose only
argument is a general context. This function builds a set of character tables
in the current locale.
+<b>int pcre2_set_max_pattern_length(pcre2_compile_context *<i>ccontext</i>,</b>
+<b> PCRE2_SIZE <i>value</i>);</b>
+<br>
+<br>
+This sets a maximum length, in code units, for the pattern string that is to be
+compiled. 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 effectively unlimited.
<b>int pcre2_set_newline(pcre2_compile_context *<i>ccontext</i>,</b>
<b> uint32_t <i>value</i>);</b>
<br>
@@ -2622,7 +2636,9 @@
This function calls <b>pcre2_match()</b> and then makes a copy of the subject
string in <i>outputbuffer</i>, replacing the part that was matched with the
<i>replacement</i> string, whose length is supplied in <b>rlength</b>. This can
-be given as PCRE2_ZERO_TERMINATED for a zero-terminated string.
+be given as PCRE2_ZERO_TERMINATED for a zero-terminated string. 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.
</P>
<P>
The first seven arguments of <b>pcre2_substitute()</b> are the same as for
@@ -2735,8 +2751,9 @@
is not big enough. 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_REPMISSING_BRACE (closing curly bracket not found), and
-PCRE2_BADSUBSTITUTION (syntax error in extended group substitution). As for all
+PCRE2_ERROR_REPMISSING_BRACE (closing curly bracket not found),
+PCRE2_BADSUBSTITUTION (syntax error in extended group substitution), and
+PCRE2_BADSUBPATTERN (the pattern match ended before it started). As for all
PCRE2 errors, a text message that describes the error can be obtained by
calling <b>pcre2_get_error_message()</b>.
</P>
@@ -3015,7 +3032,7 @@
</P>
<br><a name="SEC40" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 16 October 2015
+Last updated: 05 November 2015
<br>
Copyright © 1997-2015 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcre2limits.html
===================================================================
--- code/trunk/doc/html/pcre2limits.html 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/html/pcre2limits.html 2015-11-05 17:33:39 UTC (rev 414)
@@ -32,6 +32,11 @@
linkage size is always 4.
</P>
<P>
+The maximum length of a source pattern string is essentially unlimited; it is
+the largest number a PCRE2_SIZE variable can hold. However, the program that
+calls <b>pcre2_compile()</b> can specify a smaller limit.
+</P>
+<P>
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
@@ -50,6 +55,9 @@
All values in repeating quantifiers must be less than 65536.
</P>
<P>
+The maximum length of a lookbehind assertion is 65535 characters.
+</P>
+<P>
There is no limit to the number of parenthesized subpatterns, but there can be
no more than 65535 capturing subpatterns. There is, however, a limit to the
depth of nesting of parenthesized subpatterns of all kinds. This is imposed in
@@ -85,9 +93,9 @@
REVISION
</b><br>
<P>
-Last updated: 25 November 2014
+Last updated: 05 November 2015
<br>
-Copyright © 1997-2014 University of Cambridge.
+Copyright © 1997-2015 University of Cambridge.
<br>
<p>
Return to the <a href="index.html">PCRE2 index page</a>.
Modified: code/trunk/doc/html/pcre2pattern.html
===================================================================
--- code/trunk/doc/html/pcre2pattern.html 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/html/pcre2pattern.html 2015-11-05 17:33:39 UTC (rev 414)
@@ -2512,7 +2512,8 @@
(?(VERSION>=10.4)yes|no)
</pre>
This pattern matches "yes" if the PCRE2 version is greater or equal to 10.4, or
-"no" otherwise.
+"no" otherwise. The fractional part of the version number may not contain more
+than two digits.
</P>
<br><b>
Assertion conditions
@@ -3358,7 +3359,7 @@
</P>
<br><a name="SEC30" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 16 October 2015
+Last updated: 01 November 2015
<br>
Copyright © 1997-2015 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcre2posix.html
===================================================================
--- code/trunk/doc/html/pcre2posix.html 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/html/pcre2posix.html 2015-11-05 17:33:39 UTC (rev 414)
@@ -266,9 +266,11 @@
The <b>regerror()</b> function maps a non-zero errorcode from either
<b>regcomp()</b> or <b>regexec()</b> to a printable message. If <i>preg</i> is not
NULL, the error should have arisen from the use of that structure. A message
-terminated by a binary zero is placed in <i>errbuf</i>. The length of the
-message, including the zero, is limited to <i>errbuf_size</i>. The yield of the
-function is the size of buffer needed to hold the whole message.
+terminated by a binary zero is placed in <i>errbuf</i>. If the buffer is too
+short, only the first <i>errbuf_size</i> - 1 characters of the error 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
+<i>errbuf_size</i> if the message was truncated.
</P>
<br><a name="SEC7" href="#TOC1">MEMORY USAGE</a><br>
<P>
@@ -287,7 +289,7 @@
</P>
<br><a name="SEC9" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 03 September 2015
+Last updated: 30 October 2015
<br>
Copyright © 1997-2015 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcre2serialize.html
===================================================================
--- code/trunk/doc/html/pcre2serialize.html 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/html/pcre2serialize.html 2015-11-05 17:33:39 UTC (rev 414)
@@ -41,12 +41,12 @@
expression patterns, it may be useful to store them in a precompiled form
instead of having to compile them every time the application is run. However,
if you are using the just-in-time optimization feature, it is not possible to
-save and reload the JIT data, because it is position-dependent. In addition,
-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 endianness,
-pointer width and PCRE2_SIZE type. For example, patterns compiled on a 32-bit
-system using PCRE2's 16-bit library cannot be reloaded on a 64-bit system, nor
-can they be reloaded using the 8-bit library.
+save and reload the JIT data, because it is position-dependent. 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 endianness, pointer width
+and PCRE2_SIZE type. For example, patterns compiled on a 32-bit system using
+PCRE2's 16-bit library cannot be reloaded on a 64-bit system, nor can they be
+reloaded using the 8-bit library.
</P>
<br><a name="SEC2" href="#TOC1">SAVING COMPILED PATTERNS</a><br>
<P>
@@ -153,10 +153,15 @@
</P>
<P>
Decoded patterns can be used for matching in the usual way, and must be freed
-by calling <b>pcre2_code_free()</b> as normal. A single copy of the character
-tables is used by all the decoded patterns. A reference count is used to
+by calling <b>pcre2_code_free()</b>. 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 and a reference count is used to
arrange for its memory to be automatically freed when the last pattern is
-freed.
+freed, but there is no locking on this reference count. Therefore, if you want
+to call <b>pcre2_code_free()</b> for these patterns in different threads, you
+must arrange your own locking, and ensure that <b>pcre2_code_free()</b> cannot
+be called by two threads at the same time.
</P>
<P>
If a pattern was processed by <b>pcre2_jit_compile()</b> before being
@@ -175,7 +180,7 @@
</P>
<br><a name="SEC5" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 20 January 2015
+Last updated: 03 November 2015
<br>
Copyright © 1997-2015 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcre2test.html
===================================================================
--- code/trunk/doc/html/pcre2test.html 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/html/pcre2test.html 2015-11-05 17:33:39 UTC (rev 414)
@@ -266,9 +266,9 @@
multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
etc., depending on the newline setting) in a single line of input to encode the
newline sequences. There is no limit on the length of subject lines; the input
-buffer is automatically extended if it is too small. There is a replication
-feature that makes it possible to generate long subject lines without having to
-supply them explicitly.
+buffer is automatically extended if it is too small. There are replication
+features that makes it possible to generate long repetitive pattern or subject
+lines without having to supply them explicitly.
</P>
<P>
An empty line or the end of the file signals the end of the subject lines for a
@@ -500,10 +500,10 @@
</P>
<br><a name="SEC10" href="#TOC1">PATTERN MODIFIERS</a><br>
<P>
-There are three types of modifier that can appear in pattern lines, two of
-which may also be used in a <b>#pattern</b> command. A pattern's modifier list
-can add to or override default modifiers that were set by a previous
-<b>#pattern</b> command.
+There are several types of modifier that can appear in pattern lines. Except
+where noted below, they may also be used in <b>#pattern</b> commands. A
+pattern's modifier list can add to or override default modifiers that were set
+by a previous <b>#pattern</b> command.
<a name="optionmodifiers"></a></P>
<br><b>
Setting compilation options
@@ -564,6 +564,7 @@
jitfast use JIT fast path
jitverify verify JIT use
locale=<name> use this locale
+ max_pattern_length=<n> set the maximum pattern length
memory show memory used
newline=<type> set newline type
null_context compile with a NULL context
@@ -670,6 +671,34 @@
actual length of the pattern is passed.
</P>
<br><b>
+Generating long repetitive patterns
+</b><br>
+<P>
+Some tests use long patterns that are very repetitive. Instead of creating a
+very long input line for such a pattern, you can use a special repetition
+feature, similar to the one described for subject lines above. If the
+<b>expand</b> modifier is present on a pattern, parts of the pattern that have
+the form
+<pre>
+ \[<characters>]{<count>}
+</pre>
+are expanded before the pattern is passed to <b>pcre2_compile()</b>. For
+example, \[AB]{6000} is expanded to "ABAB..." 6000 times. This construction
+cannot be nested. An initial "\[" sequence is recognized only if "]{" followed
+by decimal digits and "}" is found later in the pattern. If not, the characters
+remain in the pattern unaltered.
+</P>
+<P>
+If part of an expanded pattern looks like an expansion, but is really part of
+the actual pattern, unwanted expansion can be avoided by giving two values in
+the quantifier. For example, \[AB]{6000,6000} is not recognized as an
+expansion item.
+</P>
+<P>
+If the <b>info</b> modifier is set on an expanded pattern, the result of the
+expansion is included in the information that is output.
+</P>
+<br><b>
JIT compilation
</b><br>
<P>
@@ -780,6 +809,15 @@
suite.
</P>
<br><b>
+Limiting the pattern length
+</b><br>
+<P>
+The <b>max_pattern_length</b> modifier sets a limit, in code units, to the
+length of pattern that <b>pcre2_compile()</b> will accept. Breaching the limit
+causes a compilation error. The default is the largest number a PCRE2_SIZE
+variable can hold (essentially unlimited).
+</P>
+<br><b>
Using the POSIX wrapper API
</b><br>
<P>
@@ -798,6 +836,16 @@
ucp REG_UCP ) the POSIX standard
utf REG_UTF8 )
</pre>
+The <b>regerror_buffsize</b> modifier specifies a size for the error buffer that
+is passed to <b>regerror()</b> in the event of a compilation error. For example:
+<pre>
+ /abc/posix,regerror_buffsize=20
+</pre>
+This provides a means of testing the behaviour of <b>regerror()</b> when the
+buffer is too small for the error message. If this modifier has not been set, a
+large buffer is used.
+</P>
+<P>
The <b>aftertext</b> and <b>allaftertext</b> subject modifiers work as described
below. All other modifiers cause an error.
</P>
@@ -840,8 +888,9 @@
<P>
The following modifiers are really subject modifiers, and are described below.
However, they may be included in a pattern's modifier list, in which case they
-are applied to every subject line that is processed with that pattern. They do
-not affect the compilation process.
+are applied to every subject line that is processed with that pattern. They may
+not appear in <b>#pattern</b> commands. These modifiers do not affect the
+compilation process.
<pre>
aftertext show text after match
allaftertext show text after captures
@@ -1574,7 +1623,7 @@
</P>
<br><a name="SEC21" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 17 October 2015
+Last updated: 05 November 2015
<br>
Copyright © 1997-2015 University of Cambridge.
<br>
Modified: code/trunk/doc/index.html.src
===================================================================
--- code/trunk/doc/index.html.src 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/index.html.src 2015-11-05 17:33:39 UTC (rev 414)
@@ -210,12 +210,15 @@
<tr><td><a href="pcre2_set_match_limit.html">pcre2_set_match_limit</a></td>
<td> Set the match limit</td></tr>
-<tr><td><a href="pcre2_set_offset_limit.html">pcre2_set_offset_limit</a></td>
- <td> Set the offset limit</td></tr>
+<tr><td><a href="pcre2_set_max_pattern_length.html">pcre2_set_max_pattern_length</a></td>
+ <td> Set the maximum length of pattern</td></tr>
<tr><td><a href="pcre2_set_newline.html">pcre2_set_newline</a></td>
<td> Set the newline convention</td></tr>
+<tr><td><a href="pcre2_set_offset_limit.html">pcre2_set_offset_limit</a></td>
+ <td> Set the offset limit</td></tr>
+
<tr><td><a href="pcre2_set_parens_nest_limit.html">pcre2_set_parens_nest_limit</a></td>
<td> Set the parentheses nesting limit</td></tr>
Modified: code/trunk/doc/pcre2.txt
===================================================================
--- code/trunk/doc/pcre2.txt 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/pcre2.txt 2015-11-05 17:33:39 UTC (rev 414)
@@ -252,6 +252,9 @@
int pcre2_set_character_tables(pcre2_compile_context *ccontext,
const unsigned char *tables);
+ int pcre2_set_max_pattern_length(pcre2_compile_context *ccontext,
+ PCRE2_SIZE value);
+
int pcre2_set_newline(pcre2_compile_context *ccontext,
uint32_t value);
@@ -678,6 +681,7 @@
PCRE2's character tables
The newline character sequence
The compile time nested parentheses limit
+ The maximum length of the pattern string
An external function for stack checking
A compile context is also required if you are using custom memory man-
@@ -715,19 +719,29 @@
only argument is a general context. This function builds a set of char-
acter tables in the current locale.
+ int pcre2_set_max_pattern_length(pcre2_compile_context *ccontext,
+ PCRE2_SIZE value);
+
+ This sets a maximum length, in code units, for the pattern string that
+ is to be compiled. 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 effectively unlim-
+ ited.
+
int pcre2_set_newline(pcre2_compile_context *ccontext,
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
+ two-character sequence CR followed by LF), PCRE2_NEWLINE_ANYCRLF (any
of the above), or PCRE2_NEWLINE_ANY (any Unicode newline sequence).
When a pattern is compiled with the PCRE2_EXTENDED option, the value of
- this parameter affects the recognition of white space and the end of
+ this parameter affects the recognition of white space and 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 inter-
+ pattern for subsequent use by the JIT compiler and by the two inter-
preted matching functions, pcre2_match() and pcre2_dfa_match().
int pcre2_set_parens_nest_limit(pcre2_compile_context *ccontext,
@@ -734,23 +748,23 @@
uint32_t value);
This parameter ajusts the limit, set when PCRE2 is built (default 250),
- on the depth of parenthesis nesting in a pattern. This limit stops
+ on the depth of parenthesis nesting in a pattern. This limit stops
rogue patterns using up too much system stack when being compiled.
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. 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
+ 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. 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
@@ -764,10 +778,10 @@
The limit for calling match() recursively
A match context is also required if you are using custom memory manage-
- ment. If none of these apply, just pass NULL as the context argument
+ ment. 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(
@@ -778,7 +792,7 @@
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.
@@ -786,7 +800,7 @@
int (*callout_function)(pcre2_callout_block *, void *),
void *callout_data);
- This sets up a "callout" function, which PCRE2 will call at specified
+ This sets up a "callout" function, which PCRE2 will call at specified
points during a matching operation. Details are given in the pcre2call-
out documentation.
@@ -793,59 +807,59 @@
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
+ 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. For example, if the pattern /abc/ is matched
- against "123abc" with an offset limit less than 3, the result is
- PCRE2_ERROR_NO_MATCH. A match can never be found if the startoffset
+ against "123abc" with an offset limit less than 3, the result is
+ PCRE2_ERROR_NO_MATCH. A match can never be found if the startoffset
argument of pcre2_match() or pcre2_dfa_match() is greater than the off-
set limit.
- When using this facility, you must set PCRE2_USE_OFFSET_LIMIT 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
+ When using this facility, you must set PCRE2_USE_OFFSET_LIMIT 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. See also the PCRE2_FIRSTLINE option, which
+ The offset limit facility can be used to track progress when searching
+ large subject strings. See also the PCRE2_FIRSTLINE option, which
requires a match to start within the first line of the subject.
int pcre2_set_match_limit(pcre2_match_context *mcontext,
uint32_t value);
- The match_limit parameter provides a means of preventing PCRE2 from
+ The match_limit parameter provides a means of preventing PCRE2 from
using up too many 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 nested unlim-
+ to match, but which have a very large number of possibilities in their
+ search trees. The classic example is a pattern that uses nested unlim-
ited repeats.
- Internally, pcre2_match() uses a function called match(), which it
- calls repeatedly (sometimes recursively). The limit set by match_limit
- is imposed on the number of times this function is called during a
+ Internally, pcre2_match() uses a function called match(), which it
+ calls repeatedly (sometimes recursively). The limit set by match_limit
+ is imposed on the number of times this function is called during a
match, which 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 is not
+ can take place. For patterns that are not anchored, the count restarts
+ from zero for each position in the subject string. This limit is not
relevant to pcre2_dfa_match(), which ignores it.
- 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. If the limit is exceeded, pcre2_match() returns
- PCRE2_ERROR_MATCHLIMIT. A value for the match limit may also be sup-
+ 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. If the limit is exceeded, pcre2_match() returns
+ PCRE2_ERROR_MATCHLIMIT. A value for the match limit may also be sup-
plied 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()
+ 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.
int pcre2_set_recursion_limit(pcre2_match_context *mcontext,
@@ -852,27 +866,27 @@
uint32_t value);
The recursion_limit parameter is similar to match_limit, but instead of
- limiting the total number of times that match() is called, it limits
- the depth of recursion. The recursion depth is a smaller number than
- the total number of calls, because not all calls to match() are recur-
+ limiting the total number of times that match() is called, it limits
+ the depth of recursion. The recursion depth is a smaller number than
+ the total number of calls, because not all calls to match() are recur-
sive. This limit is of use only if it is set smaller than match_limit.
Limiting the recursion depth limits the amount of system stack that can
- be used, or, when PCRE2 has been compiled to use memory on the heap
- instead of the stack, the amount of heap memory that can be used. This
- limit is not relevant, and is ignored, when matching is done using JIT
+ be used, or, when PCRE2 has been compiled to use memory on the heap
+ instead of the stack, the amount of heap memory that can be used. This
+ limit is not relevant, and is ignored, when matching is done using JIT
compiled code or by the pcre2_dfa_match() function.
- The default value for recursion_limit can be set when PCRE2 is built;
- the default default is the same value as the default for match_limit.
- If the limit is exceeded, pcre2_match() returns PCRE2_ERROR_RECURSION-
- LIMIT. A value for the recursion limit may also be supplied by an item
+ The default value for recursion_limit can be set when PCRE2 is built;
+ the default default is the same value as the default for match_limit.
+ If the limit is exceeded, pcre2_match() returns PCRE2_ERROR_RECURSION-
+ LIMIT. A value for the recursion limit may also be supplied by an item
at the start of a pattern of the form
(*LIMIT_RECURSION=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()
+ 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.
int pcre2_set_recursion_memory_management(
@@ -881,21 +895,21 @@
void (*private_free)(void *, void *), void *memory_data);
This function sets up two additional custom memory management functions
- for use by pcre2_match() when PCRE2 is compiled to use the heap for
+ for use by pcre2_match() when PCRE2 is compiled to use the heap for
remembering backtracking data, instead of recursive function calls that
- use the system stack. There is a discussion about PCRE2's stack usage
- in the pcre2stack documentation. See the pcre2build documentation for
+ use the system stack. There is a discussion about PCRE2's stack usage
+ in the pcre2stack documentation. See the pcre2build documentation for
details of how to build PCRE2.
- Using the heap for recursion is a non-standard way of building PCRE2,
- for use in environments that have limited stacks. Because of the
+ Using the heap for recursion is a non-standard way of building PCRE2,
+ for use in environments that have limited stacks. Because of the
greater use of memory management, pcre2_match() runs more slowly. Func-
- tions that are different to the general custom memory functions are
- provided so that special-purpose external code can be used for this
- case, because the memory blocks are all the same size. The blocks are
+ tions that are different to the general custom memory functions are
+ provided so that special-purpose external code can be used for this
+ case, because the memory blocks are all the same size. The blocks are
retained by pcre2_match() until it is about to exit so that they can be
- re-used when possible during the match. In the absence of these func-
- tions, the normal custom memory management functions are used, if sup-
+ re-used when possible during the match. In the absence of these func-
+ tions, the normal custom memory management functions are used, if sup-
plied, otherwise the system functions.
@@ -903,75 +917,75 @@
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
+ 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 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
+ 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.
- 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
+ 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,
+ 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.
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 +
+ unaligned)". 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
+ for all but the most massive patterns, since it allows the size of the
compiled pattern to be up to 64K code units. Larger values allow larger
- regular expressions to be compiled by those two libraries, but at the
+ 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 limit for the
- number of internal matching function calls in a pcre2_match() execu-
+ The output is a uint32_t integer that gives the default limit for the
+ number of internal matching function calls in a pcre2_match() execu-
tion. Further details are given with pcre2_match() below.
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)
@@ -980,56 +994,56 @@
PCRE2_NEWLINE_ANY Any Unicode line ending
PCRE2_NEWLINE_ANYCRLF Any of CR, LF, or CRLF
- 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_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
+ application. For finer control over compilation stack usage, see
pcre2_set_compile_recursion_guard().
PCRE2_CONFIG_RECURSIONLIMIT
- The output is a uint32_t integer that gives the default limit for the
- depth of recursion when calling the internal matching function in a
- pcre2_match() execution. Further details are given with pcre2_match()
+ The output is a uint32_t integer that gives the default limit for the
+ depth of recursion when calling the internal matching function in a
+ pcre2_match() execution. Further details are given with pcre2_match()
below.
PCRE2_CONFIG_STACKRECURSE
- The output is a uint32_t integer that is set to one if internal recur-
- sion when running pcre2_match() is implemented by recursive function
- calls that use the system stack to remember their state. This is the
- usual way that PCRE2 is compiled. The output is zero if PCRE2 was com-
- piled to use blocks of data on the heap instead of recursive function
+ The output is a uint32_t integer that is set to one if internal recur-
+ sion when running pcre2_match() is implemented by recursive function
+ calls that use the system stack to remember their state. This is the
+ usual way that PCRE2 is compiled. The output is zero if PCRE2 was com-
+ piled to use blocks of data on the heap instead of recursive function
calls.
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 12 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 12 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.
@@ -1043,58 +1057,58 @@
void pcre2_code_free(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, 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. The caller
- must free the memory by calling pcre2_code_free() when it is no longer
+ 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, 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. The caller
+ must free the memory by calling pcre2_code_free() when it is no longer
needed.
- 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 extraction functions. After run-
- ning a match, you must not free a compiled pattern (or a subject
- string) until after all operations on the match data block have taken
+ so that they can be referenced by the extraction functions. After run-
+ ning 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.
- 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
+ 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 options argument contains various bit settings that affect the com-
- pilation. It should be zero if no options 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
+ pilation. It should be zero if no options 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).
- 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 and PCRE2_NO_UTF_CHECK
+ 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 and PCRE2_NO_UTF_CHECK
options can be set at the time of matching as well as at compile time.
- Other, less frequently required compile-time parameters (for example,
+ Other, less frequently required compile-time parameters (for example,
the newline setting) can be provided in a compile context (as described
above).
If errorcode or erroroffset is NULL, pcre2_compile() returns NULL imme-
- diately. Otherwise, if compilation of a pattern fails, pcre2_compile()
+ diately. Otherwise, if compilation of a pattern fails, pcre2_compile()
returns NULL, having set these variables to an error code and an offset
- (number of code units) within the pattern, respectively. The
- pcre2_get_error_message() function provides a textual message for each
+ (number of code units) within the pattern, respectively. The
+ pcre2_get_error_message() function provides a textual message for each
error code. Compilation errors are positive numbers, but UTF formatting
errors are negative numbers. For an invalid UTF-8 or UTF-16 string, the
offset 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;
@@ -1108,28 +1122,28 @@
&erroffset, /* for error offset */
NULL); /* no compile context */
- 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-
@@ -1136,13 +1150,13 @@
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).
@@ -1149,53 +1163,53 @@
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
+ 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
option is set, unescaped whitespace in verb names is skipped and #-com-
ments are recognized, exactly as in the rest of the pattern.
PCRE2_AUTO_CALLOUT
- If this bit is set, pcre2_compile() automatically inserts callout
+ If this bit is set, pcre2_compile() automatically inserts callout
items, all with number 255, before each pattern item. For discussion 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
+ 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.
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, independent
of the setting of this option.
@@ -1202,175 +1216,175 @@
PCRE2_DUPNAMES
- If this bit is set, names used to identify capturing subpatterns need
+ If this bit is set, names used to identify capturing subpatterns need
not be unique. This can be helpful for certain types of pattern when it
- is known that only one instance of the named subpattern can ever be
- matched. There are more details of named subpatterns below; see also
+ is known that only one instance of the named subpattern can ever be
+ matched. There are more details of named subpatterns below; see also
the pcre2pattern documentation.
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
+ 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 subpatterns, nor within numerical quan-
- tifiers such as {1,3}. Ignorable white space is permitted between an
- item and a following quantifier and between a quantifier and a follow-
+ tifiers such as {1,3}. Ignorable white space is permitted between an
+ item and a following quantifier and between a quantifier and a follow-
ing + that indicates possessiveness.
- PCRE2_EXTENDED also causes characters between an unescaped # outside a
- character class and the next newline, inclusive, to be ignored, which
+ PCRE2_EXTENDED also causes characters between an unescaped # outside a
+ character class and the next newline, inclusive, to be ignored, which
makes it possible to include comments inside complicated patterns. Note
- that the end of this type of comment is a literal newline sequence in
+ that the end of this type of comment is a literal newline sequence in
the pattern; escape sequences that happen to represent a newline do not
- count. PCRE2_EXTENDED is equivalent to Perl's /x option, and it can be
+ count. PCRE2_EXTENDED is equivalent to Perl's /x option, and it can be
changed within a pattern by a (?x) option setting.
Which characters are interpreted as newlines can be specified by a set-
- ting in the compile context that is passed to pcre2_compile() or by a
- special sequence at the start of the pattern, as described in the sec-
- tion entitled "Newline conventions" in the pcre2pattern documentation.
+ ting in the compile context that is passed to pcre2_compile() or by a
+ special sequence at the start of the pattern, as described in the sec-
+ tion entitled "Newline conventions" in the pcre2pattern documentation.
A default is defined when PCRE2 is built.
PCRE2_FIRSTLINE
- If this option is set, an unanchored pattern is required to match
- before or at the first newline in the subject string, though the
- matched text may continue over the newline. See also PCRE2_USE_OFF-
+ If this option is set, an unanchored pattern is required to match
+ before or at the first newline in the subject string, though the
+ matched text may continue over the newline. See also PCRE2_USE_OFF-
SET_LIMIT, which provides a more general limiting facility.
PCRE2_MATCH_UNSET_BACKREF
- If this option is set, a back reference to an unset subpattern 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 back reference to an unset subpattern 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
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 ($) matches only at the end of the
+ By default, for the purposes of matching "start of line" and "end of
+ line", PCRE2 treats the subject string as consisting of a single line
+ of characters, even if it actually contains newlines. The "start of
+ line" metacharacter (^) matches only at the start of the string, and
+ the "end of line" metacharacter ($) 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,
+ 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.
- 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
+ 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.
PCRE2_NEVER_UCP
- This option locks out the use of Unicode properties for handling \B,
+ This option locks out the use of Unicode properties for handling \B,
\b, \D, \d, \S, \s, \W, \w, and some of the POSIX character classes, as
- described for the PCRE2_UCP option below. In particular, it prevents
- the creator of the pattern from enabling this facility by starting the
- pattern with (*UCP). This option may be useful in applications that
+ described for the PCRE2_UCP option below. In particular, it prevents
+ the creator of the pattern from enabling this facility by starting the
+ pattern with (*UCP). This option may be useful in applications that
process patterns from external sources. The option combination PCRE_UCP
and PCRE_NEVER_UCP causes an error.
PCRE2_NEVER_UTF
- This option locks out interpretation of the pattern as UTF-8, UTF-16,
+ 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-
+ 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.
PCRE2_NO_AUTO_CAPTURE
If this option is set, it disables the use of numbered capturing paren-
- theses in the pattern. Any opening parenthesis that is not followed by
- ? behaves as if it were followed by ?: but named parentheses can still
- be used for capturing (and they acquire numbers in the usual way).
+ theses in the pattern. Any opening parenthesis that is not followed by
+ ? behaves as if it were followed by ?: but named parentheses can still
+ be used for capturing (and they acquire numbers in the usual way).
There is no equivalent of this option in Perl.
PCRE2_NO_AUTO_POSSESS
If this option is set, it disables "auto-possessification", which is an
- optimization that, for example, turns a+b into a++b in order to avoid
- backtracks into a+ that can never be successful. However, if callouts
- are in use, auto-possessification means that some callouts are never
+ optimization that, for example, turns a+b into a++b in order to avoid
+ backtracks into a+ that can never be successful. However, if callouts
+ are in use, auto-possessification means that some callouts are never
taken. You can set this option if you want the matching functions to do
- a full unoptimized search and run all the callouts, but it is mainly
+ a full unoptimized search and run all the callouts, but it is mainly
provided for testing purposes.
PCRE2_NO_DOTSTAR_ANCHOR
If this option is set, it disables an optimization that is applied when
- .* is the first significant item in a top-level branch of a pattern,
- and all the other branches also start with .* or with \A or \G or ^.
- The optimization is automatically disabled for .* if it is inside an
- atomic group or a capturing group that is the subject of a back refer-
- ence, or if the pattern contains (*PRUNE) or (*SKIP). When the opti-
- mization is not disabled, such a pattern is automatically anchored if
+ .* is the first significant item in a top-level branch of a pattern,
+ and all the other branches also start with .* or with \A or \G or ^.
+ The optimization is automatically disabled for .* if it is inside an
+ atomic group or a capturing group that is the subject of a back refer-
+ ence, or if the pattern contains (*PRUNE) or (*SKIP). When the opti-
+ mization is not disabled, such a pattern is automatically anchored if
PCRE2_DOTALL is set for all the .* items and PCRE2_MULTILINE is not set
- for any ^ items. Otherwise, the fact that any match must start either
- at the start of the subject or following a newline is remembered. Like
+ for any ^ items. Otherwise, the fact that any match must start either
+ at the start of the subject or following a newline is remembered. Like
other optimizations, this can cause callouts to be skipped.
PCRE2_NO_START_OPTIMIZE
- This is an option whose main effect is at matching time. It does not
+ This is an option whose main effect is at matching time. It does not
change what pcre2_compile() generates, but it does affect the output of
the JIT compiler.
- There are a number of optimizations that may occur at the start of a
- match, in order to speed up the process. For example, if it is known
- that an unanchored match must start with a specific character, the
- matching code searches the subject for that character, and fails imme-
- diately if it cannot find it, without actually running the main match-
- ing function. This means that a special item such as (*COMMIT) at the
- start of a pattern is not considered until after a suitable starting
- point for the match has been found. Also, when callouts or (*MARK)
- items are in use, these "start-up" optimizations can cause them to be
- skipped if the pattern is never actually used. The start-up optimiza-
- tions are in effect a pre-scan of the subject that takes place before
+ There are a number of optimizations that may occur at the start of a
+ match, in order to speed up the process. For example, if it is known
+ that an unanchored match must start with a specific character, the
+ matching code searches the subject for that character, and fails imme-
+ diately if it cannot find it, without actually running the main match-
+ ing function. This means that a special item such as (*COMMIT) at the
+ start of a pattern is not considered until after a suitable starting
+ point for the match has been found. Also, when callouts or (*MARK)
+ items are in use, these "start-up" optimizations can cause them to be
+ skipped if the pattern is never actually used. The start-up optimiza-
+ tions are in effect a pre-scan of the subject that takes place before
the pattern is run.
The PCRE2_NO_START_OPTIMIZE option disables the start-up optimizations,
- possibly causing performance to suffer, but ensuring that in cases
- where the result is "no match", the callouts do occur, and that items
+ possibly causing performance to suffer, but ensuring that in cases
+ where the result is "no match", the callouts do occur, and that items
such as (*COMMIT) and (*MARK) are considered at every possible starting
position in the subject string.
- Setting PCRE2_NO_START_OPTIMIZE may change the outcome of a matching
+ Setting PCRE2_NO_START_OPTIMIZE may change the outcome of a matching
operation. Consider the pattern
(*COMMIT)ABC
- When this is compiled, PCRE2 records the fact that a match must start
- with the character "A". Suppose the subject string is "DEFABC". The
- start-up optimization scans along the subject, finds "A" and runs the
- first match attempt from there. The (*COMMIT) item means that the pat-
- tern must match the current starting position, which in this case, it
- 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
+ When this is compiled, PCRE2 records the fact that a match must start
+ with the character "A". Suppose the subject string is "DEFABC". The
+ start-up optimization scans along the subject, finds "A" and runs the
+ first match attempt from there. The (*COMMIT) item means that the pat-
+ tern must match the current starting position, which in this case, it
+ 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". There are also other start-up optimizations. For
example, a minimum length for the subject may be recorded. Consider the
pattern
@@ -1377,73 +1391,73 @@
(*MARK:A)(X|Y)
- The minimum length for a match is one character. If the subject is
+ The minimum length for a match is one character. If the subject is
"ABC", there will be attempts to match "ABC", "BC", and "C". An attempt
to match an empty string at the end of the subject does not take place,
- because PCRE2 knows that the subject is now too short, and so the
- (*MARK) is never encountered. In this case, the optimization does not
+ because PCRE2 knows that the subject is now too short, and so the
+ (*MARK) is never encountered. In this case, the optimization does not
affect the overall match result, which is still "no match", but it does
affect the auxiliary information that is returned.
PCRE2_NO_UTF_CHECK
- When PCRE2_UTF is set, the validity of the pattern as a UTF string is
- automatically checked. There are discussions about the validity of
- UTF-8 strings, UTF-16 strings, and UTF-32 strings in the pcre2unicode
+ When PCRE2_UTF is set, the validity of the pattern as a UTF string is
+ automatically checked. There are discussions about the validity of
+ UTF-8 strings, UTF-16 strings, and UTF-32 strings in the pcre2unicode
document. If an invalid UTF sequence is found, pcre2_compile() returns
a negative error code.
If you know that your pattern is valid, 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 pat-
- tern is undefined. It may cause your program to crash or loop. Note
- that this option can also be passed to pcre2_match() and
+ 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 pat-
+ tern is undefined. It may cause your program to crash or loop. Note
+ that this option can also be passed to pcre2_match() and
pcre_dfa_match(), to suppress validity checking of the subject string.
PCRE2_UCP
This option changes the way PCRE2 processes \B, \b, \D, \d, \S, \s, \W,
- \w, and some of the POSIX character classes. By default, only ASCII
- characters are recognized, but if PCRE2_UCP is set, Unicode properties
- are used instead to classify characters. More details are given in the
+ \w, and some of the POSIX character classes. By default, only ASCII
+ characters are recognized, but if PCRE2_UCP is set, Unicode properties
+ are used instead to classify characters. More details are given in the
section on generic character types in the pcre2pattern page. If you set
- PCRE2_UCP, matching one of the items it affects takes much longer. The
- option is available only if PCRE2 has been compiled with Unicode sup-
+ PCRE2_UCP, matching one of the items it affects takes much longer. The
+ option is available only if PCRE2 has been compiled with Unicode sup-
port.
PCRE2_UNGREEDY
- This option inverts the "greediness" of the quantifiers so that they
- are not greedy by default, but become greedy if followed by "?". It is
- not compatible with Perl. It can also be set by a (?U) option setting
+ This option inverts the "greediness" of the quantifiers so that they
+ are not greedy by default, but become greedy if followed by "?". It is
+ not compatible with Perl. It can also be set by a (?U) option setting
within the pattern.
PCRE2_USE_OFFSET_LIMIT
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
+ 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
match contexts. See also the PCRE2_FIRSTLINE option above.
PCRE2_UTF
- This option causes PCRE2 to regard both the pattern and the subject
- 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 this option changes the behaviour of PCRE2 are given in
+ This option causes PCRE2 to regard both the pattern and the subject
+ 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 this option changes the behaviour of PCRE2 are given in
the pcre2unicode page.
COMPILATION ERROR CODES
- There are over 80 positive error codes that pcre2_compile() may return
+ There are over 80 positive error codes that pcre2_compile() may return
if it finds an error in the pattern. There are also some negative error
- codes that are used for invalid UTF strings. These are the same as
- given by pcre2_match() and pcre2_dfa_match(), and are described in the
+ codes that are used for invalid UTF strings. These are the same as
+ given by pcre2_match() and pcre2_dfa_match(), and are described in the
pcre2unicode page. The pcre2_get_error_message() function can be called
to obtain a textual error message from any error code.
@@ -1467,53 +1481,53 @@
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 UTF
- 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
+ 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 UTF
+ 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
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
+ 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
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
+ example, to build and use tables that are appropriate for the French
+ locale (where accented characters with values greater than 128 are
treated as letters), the following code could be used:
setlocale(LC_CTYPE, "fr_FR");
@@ -1522,15 +1536,15 @@
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 all 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 all happen in the same locale, but different
patterns can be processed in different locales.
@@ -1538,13 +1552,13 @@
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
+ 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
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:
@@ -1554,9 +1568,9 @@
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;
@@ -1573,16 +1587,16 @@
PCRE2_INFO_ARGOPTIONS
Return a copy 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 option
- settings at the start of the pattern itself. In other words, they are
+ 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 option
+ settings at the start of the pattern itself. In other words, they are
the options that will be in force when matching starts. For example, if
the pattern /(?im)abc(?-i)d/ is compiled with the PCRE2_EXTENDED
- option, the result is PCRE2_CASELESS, PCRE2_MULTILINE, and
+ option, the result is PCRE2_CASELESS, PCRE2_MULTILINE, and
PCRE2_EXTENDED.
- 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:
@@ -1591,7 +1605,7 @@
\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
@@ -1601,18 +1615,18 @@
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 back reference in the pattern. The
- third argument should point to an uint32_t variable. Named subpatterns
- acquire numbers as well as names, and these count towards the highest
- back reference. Back references such as \4 or \g{12} match the cap-
- tured characters of the given group, but in addition, the check that a
+ Return the number of the highest back reference in the pattern. The
+ third argument should point to an uint32_t variable. Named subpatterns
+ acquire numbers as well as names, and these count towards the highest
+ back reference. Back references such as \4 or \g{12} match the cap-
+ tured characters of the given group, but in addition, the check that a
capturing group is set in a conditional subpattern such as (?(3)a|b) is
- also a back reference. Zero is returned if there are no back refer-
+ also a back reference. Zero is returned if there are no back refer-
ences.
PCRE2_INFO_BSR
@@ -1619,122 +1633,122 @@
The output is a uint32_t 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_ANY-
+ \R matches any Unicode line ending sequence; a value of PCRE2_BSR_ANY-
CRLF means that \R matches only CR, LF, or CRLF.
PCRE2_INFO_CAPTURECOUNT
- Return the number of capturing subpatterns in the pattern. The third
+ Return the number of capturing subpatterns in the pattern. The third
argument should point to an uint32_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
+ 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 character
- 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
+ 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 character
+ 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 in the
+ Return the value of the first code unit of any matched string in the
situation 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
+ 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.
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 an const uint8_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
+ variable. An explicit match is either a literal CR or LF character, or
\r or \n.
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
+ 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 fol-
- lows something of variable length. For example, for the pattern
- /^a\d+z\d+/ the returned value is 1 (with "z" returned from
+ lows 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 data unit that must exist in
- any matched string, other than at its start, if such a value has been
- recorded. The third argument should point to an uint32_t variable. If
+ Return the value of the rightmost literal data unit that must exist in
+ any matched string, other than at its start, if such a value has been
+ recorded. The third argument should point to an uint32_t variable. If
there is no such value, 0 is returned.
PCRE2_INFO_MATCHEMPTY
- Return 1 if the pattern can match an empty string, otherwise 0. The
+ Return 1 if the pattern can match an empty string, otherwise 0. The
third argument should point to an uint32_t variable.
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 an unsigned 32-bit integer. If no such value
- has been set, the call to pcre2_pattern_info() returns the error
+ 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 an unsigned 32-bit integer. If no such value
+ has been set, the call to pcre2_pattern_info() returns the error
PCRE2_ERROR_UNSET.
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 an
- unsigned 32-bit integer. This information is useful when doing multi-
- segment matching using the partial matching facilities. Note that the
+ hind assertion in the pattern. The third argument should point to an
+ unsigned 32-bit 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
- registers 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 pro-
+ registers 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 pro-
cessed. Otherwise, if there are no lookbehinds in the pattern, \A might
match incorrectly at the start of a new segment.
PCRE2_INFO_MINLENGTH
- If a minimum length for matching subject strings was computed, its
- value is returned. Otherwise the returned value is 0. The value is a
- number of characters, which in UTF mode may be different from the num-
- ber 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
+ If a minimum length for matching subject strings was computed, its
+ value is returned. Otherwise the returned value is 0. The value is a
+ number of characters, which in UTF mode may be different from the num-
+ ber 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
@@ -1742,50 +1756,50 @@
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
+ 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.
- 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-
+ 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.
+ 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
- groups with the same number, as described in the section on duplicate
- subpattern numbers in the pcre2pattern page, the groups may be given
- the same name, but there is only one entry in the table. Different
+ The names are in alphabetical order. If (?| is used to create multiple
+ groups with the same number, as described in the section on duplicate
+ subpattern 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 subpatterns with different numbers are permitted,
- 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
+ Duplicate names for subpatterns with different numbers are permitted,
+ 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 subpatterns may have lower numbers.
- 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) -
(?<month>\d\d) - (?<day>\d\d) )
- There are four named subpatterns, so the table has four entries, and
- each entry in the table is eight bytes long. The table is as follows,
+ There are four named subpatterns, so the table has four entries, and
+ 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 ??:
@@ -1794,8 +1808,8 @@
00 04 m o n t h 00
00 02 y e a r 00 ??
- When writing code to extract data from named subpatterns using the
- name-to-number map, remember that the length of the entries is likely
+ When writing code to extract data from named subpatterns 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
@@ -1808,27 +1822,27 @@
PCRE2_NEWLINE_ANY Any Unicode line ending
PCRE2_NEWLINE_ANYCRLF Any of CR, LF, or CRLF
- This specifies the default character sequence that will be recognized
+ This specifies the default character sequence that will be recognized
as meaning "newline" while matching.
PCRE2_INFO_RECURSIONLIMIT
- If the pattern set a recursion limit by including an item of the form
- (*LIMIT_RECURSION=nnnn) at the start, the value is returned. The third
- argument should point to an unsigned 32-bit integer. If no such value
- has been set, the call to pcre2_pattern_info() returns the error
+ If the pattern set a recursion limit by including an item of the form
+ (*LIMIT_RECURSION=nnnn) at the start, the value is returned. The third
+ argument should point to an unsigned 32-bit integer. If no such value
+ has been set, the call to pcre2_pattern_info() returns the error
PCRE2_ERROR_UNSET.
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
+ 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.
@@ -1839,22 +1853,22 @@
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 functions
+ It is possible to save compiled patterns on disc or elsewhere, and
+ reload them later, subject to a number of restrictions. The functions
whose names begin with pcre2_serialize_ are used for this purpose. They
are described in the pcre2serialize documentation.
@@ -1869,56 +1883,56 @@
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 know 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 know 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
- another 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
+ required to identify the string that matched the whole pattern, with
+ another 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
+ 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
+ described 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
+ 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.
- 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 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
+ 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 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.
- When a match data block itself is no longer needed, it should be freed
+ When a match data block itself is no longer needed, it should be freed
by calling pcre2_match_data_free().
@@ -1929,15 +1943,15 @@
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
+ operates in a Perl-like manner. For specialist use there is also an
+ alternative 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():
@@ -1952,7 +1966,7 @@
match_data, /* 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.
@@ -1959,67 +1973,67 @@
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
+ 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 zeroes.
- 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,
+ 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
+ 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,
+ If a non-zero starting offset is passed when the pattern is anchored,
one attempt to match at the given offset is made. This can only succeed
- if the pattern does not require the match to be at the start of the
+ if the pattern does not require the match to be at the start of the
subject.
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_NOTBOL,
+ The only bits that may be set are PCRE2_ANCHORED, PCRE2_NOTBOL,
PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART,
- PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PARTIAL_SOFT. Their
+ PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PARTIAL_SOFT. Their
action is described below.
- Setting PCRE2_ANCHORED at match time is not supported by the just-in-
- time (JIT) compiler. If it is set, JIT matching is disabled and the
+ Setting PCRE2_ANCHORED at match time is not supported by the just-in-
+ time (JIT) compiler. If it is set, JIT matching is disabled and the
normal interpretive code in pcre2_match() is run. The remaining options
are supported for JIT matching.
@@ -2026,16 +2040,16 @@
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_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.
@@ -2042,9 +2056,9 @@
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.
@@ -2051,72 +2065,72 @@
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
+ 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.
PCRE2_NO_UTF_CHECK
When PCRE2_UTF is set at compile time, the validity of the subject as a
- UTF string is checked by default when pcre2_match() is subsequently
- called. If a non-zero starting offset is given, the check is applied
- only to that part of the subject that could be inspected during match-
- ing, 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
+ UTF string is checked by default when pcre2_match() is subsequently
+ called. If a non-zero starting offset is given, the check is applied
+ only to that part of the subject that could be inspected during match-
+ ing, 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 that the
+ 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 page.
- If you know that your subject is valid, and you want to skip these
- checks for performance reasons, you can set the PCRE2_NO_UTF_CHECK
- option when calling pcre2_match(). You might want to do this for the
+ If you know that your subject is valid, and you want to skip these
+ checks 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 find all the matches in a single subject string.
- NOTE: When PCRE2_NO_UTF_CHECK is set, the effect of passing an invalid
- string as a subject, or an invalid value of startoffset, is undefined.
+ NOTE: When PCRE2_NO_UTF_CHECK is set, 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.
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
+ 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-
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.
@@ -2126,34 +2140,34 @@
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. During matching, the newline
- choice affects the behaviour of the dot, circumflex, and dollar
- metacharacters. It may also alter the way the match starting position
+ 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. During matching, the newline
+ choice affects the behaviour 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
+ 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-
+ 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 escape
- sequences. Implicit matches such as [^X] do not count, nor does \s,
+ those characters in the pattern, or one of the \r or \n escape
+ sequences. Implicit matches such as [^X] do not count, nor does \s,
even though it includes CR and LF in the characters 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.
@@ -2164,84 +2178,84 @@
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 "capturing subpattern" or "capturing group" is used for a frag-
- ment of a pattern that picks out a substring. PCRE2 supports several
+ 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 "capturing subpattern" or "capturing group" is used for a frag-
+ ment of a pattern that picks out a substring. PCRE2 supports several
other kinds of parenthesized subpattern that do not cause substrings to
- be captured. The pcre2_pattern_info() function can be used to find out
+ be captured. The pcre2_pattern_info() function can be used to find out
how many capturing subpatterns there are in a compiled pattern.
- A successful match returns the overall matched string and any captured
- substrings to the caller via a vector of PCRE2_SIZE values. This is
- called the ovector, and is contained within the match data block. You
- can obtain direct access to the ovector by calling pcre2_get_ovec-
- tor_pointer() to find its address, and pcre2_get_ovector_count() to
- find the number of pairs of values it contains. Alternatively, you can
+ A successful match returns the overall matched string and any captured
+ substrings to the caller via a vector of PCRE2_SIZE values. This is
+ called the ovector, and is contained within the match data block. You
+ can obtain direct access to the ovector by calling pcre2_get_ovec-
+ tor_pointer() to find its address, and pcre2_get_ovector_count() to
+ find the number of pairs of values it contains. Alternatively, you can
use the auxiliary functions for accessing captured substrings by number
or by name (see below).
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
+ 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.
- 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 successful match, the first pair of offsets identifies the por-
- tion of the subject string that was matched by the entire pattern. The
- next pair is used for the first capturing subpattern, 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 cap-
- tured, the returned value is 3. If there are no capturing subpatterns,
+ tion of the subject string that was matched by the entire pattern. The
+ next pair is used for the first capturing subpattern, 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 cap-
+ tured, the returned value is 3. If there are no capturing subpatterns,
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 capturing subpattern group is matched repeatedly within a single
- match operation, it is the last portion of the subject that it matched
+ If a capturing subpattern group is matched repeatedly within a single
+ match operation, it is the last portion of the subject that it matched
that is returned.
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). However, if the pattern contains back references and the
ovector is not big enough to remember the related substrings, PCRE2 has
- to get additional memory for use during matching. Thus it is usually
+ to get additional memory for use during matching. Thus it is usually
advisable to set up a match data block containing an ovector of reason-
able size.
- It is possible for capturing subpattern number n+1 to match some part
+ It is possible for capturing subpattern number n+1 to match some part
of the subject when subpattern n has not been used at all. For example,
- if the string "abc" is matched against the pattern (a|(z))(bc) the
+ if the string "abc" is matched against the pattern (a|(z))(bc) the
return from the function is 4, and subpatterns 1 and 3 are matched, but
- 2 is not. When this happens, both values in the offset pairs corre-
+ 2 is not. When this happens, both values in the offset pairs corre-
sponding to unused subpatterns are set to PCRE2_UNSET.
- Offset values that correspond to unused subpatterns at the end of the
- expression are also set to PCRE2_UNSET. For example, if the string
+ Offset values that correspond to unused subpatterns 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)?)? subpatterns 2 and 3
- are not matched. The return from the function is 2, because the high-
+ are not matched. The return from the function is 2, because the high-
est used capturing subpattern number is 1. The offsets for for the sec-
- ond and third capturing subpatterns (assuming the vector is large
+ ond and third capturing subpatterns (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-
+ pcre2_match(). The other elements retain whatever values they previ-
ously had.
@@ -2251,37 +2265,37 @@
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 avail-
- able, and pcre2_get_mark() can be called. It returns a pointer to the
- zero-terminated name, which is within the compiled pattern. Otherwise
- NULL is returned. After a successful match, the (*MARK) name that is
- returned is the last one encountered on the matching path through the
- pattern. After a "no match" or a partial match, the last encountered
+ After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
+ failure to match (PCRE2_ERROR_NOMATCH), a (*MARK) name may be avail-
+ able, and pcre2_get_mark() can be called. It returns a pointer to the
+ zero-terminated name, which is within the compiled pattern. Otherwise
+ NULL is returned. After a successful match, the (*MARK) name that is
+ returned is the last one encountered on the matching path through the
+ pattern. After a "no match" or a partial match, the last encountered
(*MARK) name is returned. For example, consider this pattern:
^(*MARK:A)((*MARK:B)a|b)c
- When it matches "bc", the returned mark 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 mark 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
mark is B.
- 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.
@@ -2288,12 +2302,12 @@
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 pcre2_get_error_message(). Negative
- error codes are also returned by other functions, and are documented
+ If pcre2_match() fails, it returns a negative number. This can be con-
+ verted to a text string by calling pcre2_get_error_message(). 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 check-
ing 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
+ 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 returned by pcre2_match():
@@ -2303,19 +2317,19 @@
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 pattern that was compiled by the 8-bit
- library is passed to a 16-bit or 32-bit library function, or vice
+ This error is given when a pattern that was compiled by the 8-bit
+ library is passed to a 16-bit or 32-bit library function, or vice
versa.
PCRE2_ERROR_BADOFFSET
@@ -2329,35 +2343,35 @@
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_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_BADOPTION
- This error is returned when a pattern that was successfully studied
- using JIT is being matched, but the matching mode (partial or complete
- match) does not correspond to any JIT compilation mode. When the JIT
- fast path function is used, this error may be also given for invalid
+ This error is returned when a pattern that was successfully studied
+ using JIT is being matched, but the matching mode (partial or complete
+ match) does not correspond to any JIT compilation mode. When the JIT
+ fast path function is used, this error may be also given for invalid
options. See the pcre2jit documentation for more details.
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-
+ 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.
PCRE2_ERROR_MATCHLIMIT
@@ -2366,10 +2380,10 @@
PCRE2_ERROR_NOMEMORY
- If a pattern contains back references, but the ovector is not big
- enough to remember the referenced substrings, PCRE2 gets a block of
+ If a pattern contains back references, but the ovector is not big
+ enough to remember the referenced substrings, PCRE2 gets a block of
memory at the start of matching to use for this purpose. There are some
- other special cases where extra memory is needed during matching. This
+ other special cases where extra memory is needed during matching. This
error is given when memory cannot be obtained.
PCRE2_ERROR_NULL
@@ -2378,12 +2392,12 @@
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 subpattern 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
+ 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
subpatterns, cannot be detected until matching is attempted.
PCRE2_ERROR_RECURSIONLIMIT
@@ -2406,39 +2420,39 @@
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
capturing group number.
The final arguments of pcre2_substring_copy_bynumber() are a pointer to
@@ -2447,25 +2461,25 @@
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
+ after 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
@@ -2476,8 +2490,8 @@
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.
@@ -2488,32 +2502,32 @@
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),
+ 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
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 capturing subpattern number n+1 matches some part of the subject,
- but subpattern n has not been used at all, it returns an empty string.
- This can be distinguished from a genuine zero-length substring by
+ when capturing subpattern number n+1 matches some part of the subject,
+ but subpattern 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 substrings, or by calling pcre2_sub-
+ PCRE2_UNSET for unset substrings, or by calling pcre2_sub-
string_length_bynumber().
@@ -2533,39 +2547,39 @@
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+)...
the number of the subpattern called "xxx" is 2. If the name is known to
- be unique (PCRE2_DUPNAMES was not set), you can find the number from
+ 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
+ ment is the compiled pattern, and the second is the name. The yield of
the function is the subpattern number, PCRE2_ERROR_NOSUBSTRING if there
- is no subpattern of that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if
- there is more than one subpattern of that name. Given the number, you
- can extract the substring directly, or use one of the functions
+ is no subpattern of that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if
+ there is more than one subpattern of that name. Given the number, you
+ can extract the substring directly, or use one of the 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
+ argument 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 first named string 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,
+ 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.
Warning: If the pattern uses the (?| feature to set up multiple subpat-
- terns with the same number, as described in the section on duplicate
- subpattern numbers in the pcre2pattern page, you cannot use names to
- distinguish the different subpatterns, because names are not included
- in the compiled code. The matching process uses only numbers. For this
- reason, the use of different names for subpatterns of the same number
+ terns with the same number, as described in the section on duplicate
+ subpattern numbers in the pcre2pattern page, you cannot use names to
+ distinguish the different subpatterns, because names are not included
+ in the compiled code. The matching process uses only numbers. For this
+ reason, the use of different names for subpatterns of the same number
causes an error at compile time.
@@ -2578,31 +2592,33 @@
PCRE2_SIZE rlength, PCRE2_UCHAR *outputbufferP,
PCRE2_SIZE *outlengthptr);
- This function calls pcre2_match() and then makes a copy of the subject
- string in outputbuffer, replacing the part that was matched with the
- replacement string, whose length is supplied in rlength. This can be
- given as PCRE2_ZERO_TERMINATED for a zero-terminated string.
+ This function calls pcre2_match() and then makes a copy of the subject
+ string in outputbuffer, replacing the part that was matched with the
+ replacement string, whose length is supplied in rlength. This can be
+ given as PCRE2_ZERO_TERMINATED for a zero-terminated string. 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.
- 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.
- 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 func-
- tion is not successful, the value is set to PCRE2_UNSET for general
- errors (such as output buffer too small). For syntax errors in the
- replacement string, the value is set to the offset in the replacement
+ 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 func-
+ tion is not successful, the value is set to PCRE2_UNSET for general
+ errors (such as output buffer too small). For syntax errors in the
+ replacement string, the value is set to the offset in the replacement
string where the error was detected.
- 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
+ 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 capturing groups or (*MARK) items
+ ify the insertion of characters from capturing groups or (*MARK) items
in the pattern. The following forms are always recognized:
$$ insert a dollar character
@@ -2609,11 +2625,11 @@
$<n> or ${<n>} insert the contents of group <n>
$*MARK or ${*MARK} insert the name of the last (*MARK) encountered
- 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+=".
The facility for inserting a (*MARK) name can be used to perform simple
@@ -2623,57 +2639,57 @@
apple lemon
2: pear orange
- There is an additional option, PCRE2_SUBSTITUTE_GLOBAL, which causes
+ There is an additional option, PCRE2_SUBSTITUTE_GLOBAL, which causes
the function to iterate over the subject string, replacing every match-
ing substring. If this is not set, only the first matching substring is
replaced.
- A second additional option, PCRE2_SUBSTITUTE_EXTENDED, causes extra
- processing to be applied to the replacement string. Without this
+ A second additional option, 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 inser-
- tion forms listed above are valid. When PCRE2_SUBSTITUTE_EXTENDED is
+ tion 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 captured 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
+ ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
\E has no effect.
- The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
- flexibility to group substitution. The syntax is similar to that used
+ The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
+ flexibility to group substitution. The syntax is similar to that used
by Bash:
${<n>:-<string>}
${<n>:+<string1>:<string2>}
- As before, <n> may be a group number or a name. The first form speci-
- fies a default value. If group <n> is set, its value is inserted; if
- not, <string> is expanded and the result inserted. The second form
- specifies strings that are expanded and inserted when group <n> is set
- or unset, respectively. The first form is just a convenient shorthand
+ As before, <n> may be a group number or a name. The first form speci-
+ fies a default value. If group <n> is set, its value is inserted; if
+ not, <string> is expanded and the result inserted. The second form
+ specifies strings that are expanded and inserted when group <n> is set
+ or unset, respectively. The first form is just a convenient shorthand
for
${<n>:+${<n>}:<string>}
- Backslash can be used to escape colons and closing curly brackets in
- the replacement strings. A change of the case forcing state within a
- replacement string remains in force afterwards, as shown in this
+ Backslash can be used to escape colons and closing curly brackets in
+ the replacement strings. A change of the case forcing state within a
+ replacement string remains in force afterwards, as shown in this
pcre2test example:
/(some)?(body)/substitute_extended,replace=${1:+\U:\L}HeLLo
@@ -2682,21 +2698,22 @@
somebody
1: HELLO
- If successful, the function returns the number of replacements that
- were made. This may be zero if no matches were found, and is never
+ If successful, the function returns the number of replacements that
+ were made. This may be zero if no matches were found, and is never
greater than 1 unless PCRE2_SUBSTITUTE_GLOBAL is set.
In the event of an error, a negative error code is returned. Except for
- PCRE2_ERROR_NOMATCH (which is never returned), errors from
- pcre2_match() are passed straight back. PCRE2_ERROR_NOMEMORY is
- returned if the output buffer is not big enough.
- PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in
+ PCRE2_ERROR_NOMATCH (which is never returned), errors from
+ pcre2_match() are passed straight back. PCRE2_ERROR_NOMEMORY is
+ returned if the output buffer is not big enough.
+ 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-
- MISSING_BRACE (closing curly bracket not found), and PCRE2_BADSUBSTITU-
- TION (syntax error in extended group substitution). As for all PCRE2
- errors, a text message that describes the error can be obtained by
- calling pcre2_get_error_message().
+ PCRE2_ERROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REP-
+ MISSING_BRACE (closing curly bracket not found), PCRE2_BADSUBSTITUTION
+ (syntax error in extended group substitution), and PCRE2_BADSUBPATTERN
+ (the pattern match ended before it started). As for all PCRE2 errors, a
+ text message that describes the error can be obtained by calling
+ pcre2_get_error_message().
DUPLICATE SUBPATTERN NAMES
@@ -2957,7 +2974,7 @@
REVISION
- Last updated: 16 October 2015
+ Last updated: 05 November 2015
Copyright (c) 1997-2015 University of Cambridge.
------------------------------------------------------------------------------
@@ -4405,6 +4422,10 @@
of execution is slower. In the 32-bit library, the internal 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
+ 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
@@ -4419,6 +4440,8 @@
All values in repeating quantifiers must be less than 65536.
+ The maximum length of a lookbehind assertion is 65535 characters.
+
There is no limit to the number of parenthesized subpatterns, but there
can be no more than 65535 capturing subpatterns. There is, however, a
limit to the depth of nesting of parenthesized subpatterns of all
@@ -4449,8 +4472,8 @@
REVISION
- Last updated: 25 November 2014
- Copyright (c) 1997-2014 University of Cambridge.
+ Last updated: 05 November 2015
+ Copyright (c) 1997-2015 University of Cambridge.
------------------------------------------------------------------------------
@@ -7310,24 +7333,25 @@
(?(VERSION>=10.4)yes|no)
This pattern matches "yes" if the PCRE2 version is greater or equal to
- 10.4, or "no" otherwise.
+ 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 an
- assertion. This may be a positive or negative lookahead or lookbehind
- assertion. Consider this pattern, again containing non-significant
+ If the condition is not in any of the above formats, it must be an
+ 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
+ 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
letters and dd are digits.
@@ -7334,44 +7358,44 @@
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 subpattern name or number. The characters
+ 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 subpattern 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 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 charac-
- ters are interpreted as newlines is controlled 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 "Newline conventions"
- above. Note that the end of this type of comment is a 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 single
+ 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 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 charac-
+ ters are interpreted as newlines is controlled 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 "Newline conventions"
+ above. Note that the end of this type of comment is a 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 single
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:
@@ -7381,200 +7405,200 @@
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-
+ Instead, it supports special syntax for recursion of the entire pat-
tern, and also for individual subpattern recursion. After its introduc-
- tion in PCRE1 and Python, this kind of recursion was subsequently
+ tion 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
- subpattern of the given number, provided that it occurs inside that
- subpattern. (If not, it is a non-recursive subroutine call, which is
- described in the next section.) The special item (?R) or (?0) is a
+ A special item that consists of (? followed by a number greater than
+ zero and a closing parenthesis is a recursive subroutine call of the
+ subpattern of the given number, provided that it occurs inside that
+ subpattern. (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.
- 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-
+ 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-
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.
- It is also possible to refer to subsequently opened parentheses, by
- writing references such as (?+2). However, these cannot be recursive
- because the reference is not inside the parentheses that are refer-
- enced. They are always non-recursive subroutine calls, as described in
+ It is also possible to refer to subsequently opened parentheses, by
+ writing references such as (?+2). However, these cannot be recursive
+ because the reference is not inside the parentheses that are refer-
+ enced. 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> \( ( [^()]++ | (?&pn) )* \) )
- If there is more than one subpattern with the same name, the earliest
+ If there is more than one subpattern with the same name, the earliest
one is 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 capturing sub-
- pattern 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
+ the value for the inner capturing parentheses (numbered 2) is "ef",
+ which is the last value taken on at the top level. If a capturing sub-
+ pattern 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.
If there are more than 15 capturing parentheses in a pattern, PCRE2 has
- to obtain extra memory from the heap to store data during a recursion.
- If no memory can be obtained, the match fails with the
+ to obtain extra memory from the heap to store data during a recursion.
+ If no memory can be obtained, the match fails with the
PCRE2_ERROR_NOMEMORY error.
- 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 subpattern, with
- two different alternatives for the recursive and non-recursive cases.
+ In this pattern, (?(R) is the start of a conditional subpattern, 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
- Recursion processing in PCRE2 differs from Perl in two important ways.
+ Recursion processing in PCRE2 differs from Perl in two important ways.
In PCRE2 (like Python, but unlike Perl), a recursive subpattern call is
always treated as an atomic group. That is, once it has matched some of
the subject string, it is never re-entered, even if it contains untried
- alternatives and there is a subsequent matching failure. This can be
- illustrated by the following pattern, which purports to match a palin-
- dromic string that contains an odd number of characters (for example,
+ alternatives and there is a subsequent matching failure. This can be
+ illustrated by the following pattern, which purports to match a palin-
+ dromic string that contains an odd number of characters (for example,
"a", "aba", "abcba", "abcdcba"):
^(.|(.)(?1)\2)$
The idea is that it either matches a single character, or two identical
- characters surrounding a sub-palindrome. In Perl, this pattern works;
- in PCRE2 it does not if the pattern is longer than three characters.
+ characters surrounding a sub-palindrome. In Perl, this pattern works;
+ in PCRE2 it does not if the pattern is longer than three characters.
Consider the subject string "abcba":
- At the top level, the first character is matched, but as it is not at
+ At the top level, the first character is matched, but as it is not at
the end of the string, the first alternative fails; the second alterna-
tive is taken and the recursion kicks in. The recursive call to subpat-
- tern 1 successfully matches the next character ("b"). (Note that the
+ tern 1 successfully matches the next character ("b"). (Note that the
beginning and end of line tests are not part of the recursion).
- Back at the top level, the next character ("c") is compared with what
- subpattern 2 matched, which was "a". This fails. Because the recursion
- is treated as an atomic group, there are now no backtracking points,
- and so the entire match fails. (Perl is able, at this point, to re-
- enter the recursion and try the second alternative.) However, if the
+ Back at the top level, the next character ("c") is compared with what
+ subpattern 2 matched, which was "a". This fails. Because the recursion
+ is treated as an atomic group, there are now no backtracking points,
+ and so the entire match fails. (Perl is able, at this point, to re-
+ enter the recursion and try the second alternative.) However, if the
pattern is written with the alternatives in the other order, things are
different:
^((.)(?1)\2|.)$
- This time, the recursing alternative is tried first, and continues to
- recurse until it runs out of characters, at which point the recursion
- fails. But this time we do have another alternative to try at the
- higher level. That is the big difference: in the previous case the
- remaining alternative is at a deeper recursion level, which PCRE2 can-
+ This time, the recursing alternative is tried first, and continues to
+ recurse until it runs out of characters, at which point the recursion
+ fails. But this time we do have another alternative to try at the
+ higher level. That is the big difference: in the previous case the
+ remaining alternative is at a deeper recursion level, which PCRE2 can-
not use.
- To change the pattern so that it matches all palindromic strings, not
- just those with an odd number of characters, it is tempting to change
+ To change the pattern so that it matches all palindromic strings, not
+ just those with an odd number of characters, it is tempting to change
the pattern to this:
^((.)(?1)\2|.?)$
- Again, this works in Perl, but not in PCRE2, and for the same reason.
- When a deeper recursion has matched a single character, it cannot be
- entered again in order to match an empty string. The solution is to
- separate the two cases, and write out the odd and even cases as alter-
+ Again, this works in Perl, but not in PCRE2, and for the same reason.
+ When a deeper recursion has matched a single character, it cannot be
+ entered again in order to match an empty string. The solution is to
+ separate the two cases, and write out the odd and even cases as alter-
natives at the higher level:
^(?:((.)(?1)\2|)|((.)(?3)\4|.))
- If you want to match typical palindromic phrases, the pattern has to
+ If you want to match typical palindromic phrases, the pattern has to
ignore all non-word characters, which can be done like this:
^\W*+(?:((.)\W*+(?1)\W*+\2|)|((.)\W*+(?3)\W*+\4|\W*+.\W*+))\W*+$
- If run with the PCRE2_CASELESS option, this pattern matches phrases
- such as "A man, a plan, a canal: Panama!" and it works in both PCRE2
- and Perl. Note the use of the possessive quantifier *+ to avoid back-
- tracking into sequences of non-word characters. Without this, PCRE2
+ If run with the PCRE2_CASELESS option, this pattern matches phrases
+ such as "A man, a plan, a canal: Panama!" and it works in both PCRE2
+ and Perl. Note the use of the possessive quantifier *+ to avoid back-
+ tracking into sequences of non-word characters. Without this, PCRE2
takes a great deal longer (ten times or more) to match typical phrases,
and Perl takes so long that you think it has gone into a loop.
- WARNING: The palindrome-matching patterns above work only if the sub-
- ject string does not start with a palindrome that is shorter than the
- entire string. For example, although "abcba" is correctly matched, if
- the subject is "ababa", PCRE2 finds the palindrome "aba" at the start,
- then fails at top level because the end of the string does not follow.
- Once again, it cannot jump back into the recursion to try other alter-
+ WARNING: The palindrome-matching patterns above work only if the sub-
+ ject string does not start with a palindrome that is shorter than the
+ entire string. For example, although "abcba" is correctly matched, if
+ the subject is "ababa", PCRE2 finds the palindrome "aba" at the start,
+ then fails at top level because the end of the string does not follow.
+ Once again, it cannot jump back into the recursion to try other alter-
natives, so the entire match fails.
- The second way in which PCRE2 and Perl differ in their recursion pro-
- cessing is in the handling of captured values. In Perl, when a subpat-
- tern is called recursively or as a subpattern (see the next section),
- it has no access to any values that were captured outside the recur-
- sion, whereas in PCRE2 these values can be referenced. Consider this
+ The second way in which PCRE2 and Perl differ in their recursion pro-
+ cessing is in the handling of captured values. In Perl, when a subpat-
+ tern is called recursively or as a subpattern (see the next section),
+ it has no access to any values that were captured outside the recur-
+ sion, whereas in PCRE2 these values can be referenced. Consider this
pattern:
^(.)(\1|a(?2))
- In PCRE2, this pattern matches "bab". The first capturing parentheses
- match "b", then in the second group, when the back reference \1 fails
- to match "b", the second alternative matches "a" and then recurses. In
- the recursion, \1 does now match "b" and so the whole match succeeds.
- In Perl, the pattern fails to match because inside the recursive call
+ In PCRE2, this pattern matches "bab". The first capturing parentheses
+ match "b", then in the second group, when the back reference \1 fails
+ to match "b", the second alternative matches "a" and then recurses. In
+ the recursion, \1 does now match "b" and so the whole match succeeds.
+ In Perl, the pattern fails to match because inside the recursive call
\1 cannot access the externally set value.
SUBPATTERNS AS SUBROUTINES
- If the syntax for a recursive subpattern call (either by number or by
- name) is used outside the parentheses to which it refers, it operates
- like a subroutine in a programming language. The called subpattern may
- be defined before or after the reference. A numbered reference can be
+ If the syntax for a recursive subpattern call (either by number or by
+ name) is used outside the parentheses to which it refers, it operates
+ like a subroutine in a programming language. The called subpattern may
+ be defined before or after the reference. A numbered reference can be
absolute or relative, as in these examples:
(...(absolute)...)...(?2)...
@@ -7585,50 +7609,50 @@
(sens|respons)e and \1ibility
- matches "sense and sensibility" and "response and responsibility", but
+ matches "sense and sensibility" and "response and responsibility", but
not "sense and responsibility". If instead the pattern
(sens|respons)e and (?1)ibility
- is used, it does match "sense and responsibility" as well as the other
- two strings. Another example is given in the discussion of DEFINE
+ is used, it does match "sense and responsibility" as well as the other
+ two strings. Another example is given in the discussion of DEFINE
above.
- All subroutine calls, whether recursive or not, are always treated as
- atomic groups. That is, once a subroutine has matched some of the sub-
+ All subroutine calls, whether recursive or not, are always treated as
+ atomic groups. That is, once a subroutine has matched some of the sub-
ject string, it is never re-entered, even if it contains untried alter-
- natives and there is a subsequent matching failure. Any capturing
- parentheses that are set during the subroutine call revert to their
+ natives and there is a subsequent matching failure. Any capturing
+ parentheses that are set during the subroutine call revert to their
previous values afterwards.
- Processing options such as case-independence are fixed when a subpat-
- tern is defined, so if it is used as a subroutine, such options cannot
+ Processing options such as case-independence are fixed when a subpat-
+ tern is defined, so if it is used as a subroutine, such options cannot
be changed for different calls. For example, consider this pattern:
(abc)(?i:(?-1))
- It matches "abcabc". It does not match "abcABC" because the change of
+ It matches "abcabc". It does not match "abcABC" because the change of
processing option does not affect the called subpattern.
ONIGURUMA SUBROUTINE SYNTAX
- For compatibility with Oniguruma, the non-Perl syntax \g followed by a
+ 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 referencing a subpattern as a subroutine,
- possibly recursively. Here are two of the examples used above, rewrit-
+ an alternative syntax for referencing a subpattern as a subroutine,
+ possibly recursively. Here are two of the examples used above, rewrit-
ten using this syntax:
(?<pn> \( ( (?>[^()]+) | \g<pn> )* \) )
(sens|respons)e and \g'1'ibility
- PCRE2 supports an extension to Oniguruma: if a number is preceded by a
+ PCRE2 supports an extension to Oniguruma: if a number is preceded by a
plus or a minus sign it is taken as a relative reference. For example:
(abc)(?i:\g<-1>)
- Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are not
- synonymous. The former is a back reference; the latter is a subroutine
+ Note that \g{...} (Perl syntax) and \g<...> (Oniguruma syntax) are not
+ synonymous. The former is a back reference; the latter is a subroutine
call.
@@ -7635,54 +7659,54 @@
CALLOUTS
Perl has a feature whereby using the sequence (?{...}) causes arbitrary
- Perl code to be obeyed in the middle of matching a regular expression.
+ Perl code to be obeyed in the middle of matching a regular expression.
This makes it possible, amongst other things, to extract different sub-
strings that match the same pair of parentheses when there is a repeti-
tion.
- PCRE2 provides a similar feature, but of course it cannot obey arbi-
- trary Perl code. The feature is called "callout". The caller of PCRE2
- provides an external function by putting its entry point in a match
- context using the function pcre2_set_callout(), and then passing that
- context to pcre2_match() or pcre2_dfa_match(). If no match context is
+ PCRE2 provides a similar feature, but of course it cannot obey arbi-
+ trary Perl code. The feature is called "callout". The caller of PCRE2
+ provides an external function by putting its entry point in a match
+ context using the function pcre2_set_callout(), and then passing that
+ context to pcre2_match() or pcre2_dfa_match(). If no match context is
passed, or if the callout entry point is set to NULL, callouts are dis-
abled.
- Within a regular expression, (?C<arg>) indicates a point at which the
- external function is to be called. There are two kinds of callout:
- those with a numerical argument and those with a string argument. (?C)
- on its own with no argument is treated as (?C0). A numerical argument
- allows the application to distinguish between different callouts.
- String arguments were added for release 10.20 to make it possible for
- script languages that use PCRE2 to embed short scripts within patterns
+ Within a regular expression, (?C<arg>) indicates a point at which the
+ external function is to be called. There are two kinds of callout:
+ those with a numerical argument and those with a string argument. (?C)
+ on its own with no argument is treated as (?C0). A numerical argument
+ allows the application to distinguish between different callouts.
+ String arguments were added for release 10.20 to make it possible for
+ script languages that use PCRE2 to embed short scripts within patterns
in a similar way to Perl.
During matching, when PCRE2 reaches a callout point, the external func-
- tion is called. It is provided with the number or string argument of
- the callout, the position in the pattern, and one item of data that is
+ tion is called. It is provided with the number or string argument of
+ the callout, the position in the pattern, and one item of data that is
also set in the match block. The callout function may cause matching to
proceed, to backtrack, or to fail.
- By default, PCRE2 implements a number of optimizations at matching
- time, and one side-effect is that sometimes callouts are skipped. If
- you need all possible callouts to happen, you need to set options that
- disable the relevant optimizations. More details, including a complete
- description of the programming interface to the callout function, are
+ By default, PCRE2 implements a number of optimizations at matching
+ time, and one side-effect is that sometimes callouts are skipped. If
+ you need all possible callouts to happen, you need to set options that
+ disable the relevant optimizations. More details, including a complete
+ description of the programming interface to the callout function, are
given in the pcre2callout documentation.
Callouts with numerical arguments
- If you just want to have a means of identifying different callout
- points, put a number less than 256 after the letter C. For example,
+ If you just want to have a means of identifying different callout
+ points, put a number less than 256 after the letter C. For example,
this pattern has two callout points:
(?C1)abc(?C2)def
- If the PCRE2_AUTO_CALLOUT flag is passed to pcre2_compile(), numerical
- callouts are automatically installed before each item in the pattern.
- They are all numbered 255. If there is a conditional group in the pat-
+ If the PCRE2_AUTO_CALLOUT flag is passed to pcre2_compile(), numerical
+ callouts are automatically installed before each item in the pattern.
+ They are all numbered 255. If there is a conditional group in the pat-
tern whose condition is an assertion, an additional callout is inserted
- just before the condition. An explicit callout may also be set at this
+ just before the condition. An explicit callout may also be set at this
position, as in this example:
(?(?C9)(?=a)abc|def)
@@ -7692,57 +7716,57 @@
Callouts with string arguments
- A delimited string may be used instead of a number as a callout argu-
- ment. The starting delimiter must be one of ` ' " ^ % # $ { and the
+ A delimited string may be used instead of a number as a callout argu-
+ ment. The starting delimiter must be one of ` ' " ^ % # $ { and the
ending delimiter is the same as the start, except for {, where the end-
- ing delimiter is }. If the ending delimiter is needed within the
+ ing delimiter is }. If the ending delimiter is needed within the
string, it must be doubled. For example:
(?C'ab ''c'' d')xyz(?C{any text})pqr
- The doubling is removed before the string is passed to the callout
+ The doubling is removed before the string is passed to the callout
function.
BACKTRACKING CONTROL
- Perl 5.10 introduced a number of "Special Backtracking Control Verbs",
- which are still described in the Perl documentation as "experimental
- and subject to change or removal in a future version of Perl". It goes
- on to say: "Their usage in production code should be noted to avoid
+ Perl 5.10 introduced a number of "Special Backtracking Control Verbs",
+ which are still described in the Perl documentation as "experimental
+ and subject to change or removal in a future version of Perl". It goes
+ on to say: "Their usage in production code should be noted to avoid
problems during upgrades." The same remarks apply to the PCRE2 features
described in this section.
- The new verbs make use of what was previously invalid syntax: an open-
+ The new verbs make use of what was previously invalid syntax: an open-
ing parenthesis followed by an asterisk. They are generally of the form
(*VERB) or (*VERB:NAME). Some verbs take either form, possibly behaving
differently depending on whether or not a name is present.
- By default, for compatibility with Perl, a name is any sequence of
+ By default, for compatibility with Perl, a 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
+ 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 parenthe-
+ set, normal backslash processing is applied to verb names and only an
+ unescaped closing parenthesis terminates the name. A closing parenthe-
sis can be included in a name either as \) or between \Q and \E. If the
- PCRE2_EXTENDED option is set, unescaped whitespace in verb names is
- skipped and #-comments are recognized, exactly as in the rest of the
+ PCRE2_EXTENDED option is set, unescaped whitespace in verb names is
+ skipped and #-comments are recognized, exactly as in the rest of the
pattern.
- The maximum length of a name is 255 in the 8-bit library and 65535 in
- the 16-bit and 32-bit libraries. If the name is empty, that is, if the
- closing parenthesis immediately follows the colon, the effect is as if
+ The maximum length of a name is 255 in the 8-bit library and 65535 in
+ the 16-bit and 32-bit libraries. If the name is empty, that is, if the
+ closing parenthesis immediately follows the colon, the effect is as if
the colon were not there. Any number of these verbs may occur in a pat-
tern.
- Since these verbs are specifically related to backtracking, most of
- them can be used only when the pattern is to be matched using the tra-
+ Since these verbs are specifically related to backtracking, most of
+ them can be used only when the pattern is to be matched using the tra-
ditional matching function, because these use a backtracking algorithm.
- With the exception of (*FAIL), which behaves like a failing negative
+ With the exception of (*FAIL), which behaves like a failing negative
assertion, the backtracking control verbs cause an error if encountered
by the DFA matching function.
- The behaviour of these verbs in repeated groups, assertions, and in
+ The behaviour of these verbs in repeated groups, assertions, and in
subpatterns called as subroutines (whether or not recursively) is docu-
mented below.
@@ -7750,71 +7774,71 @@
PCRE2 contains some optimizations that are used to speed up matching by
running some checks at the start of each match attempt. For example, it
- may know the minimum length of matching subject, or that a particular
+ may know the minimum length of matching subject, or that a particular
character must be present. When one of these optimizations bypasses the
- running of a match, any included backtracking verbs will not, of
+ running of a match, any included backtracking verbs will not, of
course, be processed. You can suppress the start-of-match optimizations
- by setting the PCRE2_NO_START_OPTIMIZE option when calling pcre2_com-
- pile(), or by starting the pattern with (*NO_START_OPT). There is more
+ by setting the PCRE2_NO_START_OPTIMIZE option when calling pcre2_com-
+ pile(), or by starting the pattern with (*NO_START_OPT). There is more
discussion of this option in the section entitled "Compiling a pattern"
in the pcre2api documentation.
- Experiments with Perl suggest that it too has similar optimizations,
+ Experiments with Perl suggest that it too has similar optimizations,
sometimes leading to anomalous results.
Verbs that act immediately
- The following verbs act as soon as they are encountered. They may not
+ The following verbs act as soon as they are encountered. They may not
be followed by a name.
(*ACCEPT)
- This verb causes the match to end successfully, skipping the remainder
- of the pattern. However, when it is inside a subpattern that is called
- as a subroutine, only that subpattern is ended successfully. Matching
+ This verb causes the match to end successfully, skipping the remainder
+ of the pattern. However, when it is inside a subpattern that is called
+ as a subroutine, only that subpattern is ended successfully. Matching
then continues at the outer level. If (*ACCEPT) in triggered in a posi-
- tive assertion, the assertion succeeds; in a negative assertion, the
+ tive assertion, the assertion succeeds; in a negative assertion, the
assertion fails.
- If (*ACCEPT) is inside capturing parentheses, the data so far is cap-
+ If (*ACCEPT) is inside capturing parentheses, the data so far is cap-
tured. For example:
A((?:A|B(*ACCEPT)|C)D)
- This matches "AB", "AAD", or "ACD"; when it matches "AB", "B" is cap-
+ This matches "AB", "AAD", or "ACD"; when it matches "AB", "B" is cap-
tured by the outer parentheses.
(*FAIL) or (*F)
- This verb causes a matching failure, forcing backtracking to occur. It
- is equivalent to (?!) but easier to read. The Perl documentation notes
- that it is probably useful only when combined with (?{}) or (??{}).
- Those are, of course, Perl features that are not present in PCRE2. The
- nearest equivalent is the callout feature, as for example in this pat-
+ This verb causes a matching failure, forcing backtracking to occur. It
+ is equivalent to (?!) but easier to read. The Perl documentation notes
+ that it is probably useful only when combined with (?{}) or (??{}).
+ Those are, of course, Perl features that are not present in PCRE2. The
+ nearest equivalent is the callout feature, as for example in this pat-
tern:
a+(?C)(*FAIL)
- A match with the string "aaaa" always fails, but the callout is taken
+ A match with the string "aaaa" always fails, but the callout is taken
before each backtrack happens (in this example, 10 times).
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
+ 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).
(*MARK:NAME) or (*:NAME)
- A name is always required with this verb. There may be as many
- instances of (*MARK) as you like in a pattern, and their names do not
+ A name is always required with this verb. There may be as many
+ instances of (*MARK) as you like in a pattern, and their names do not
have to be unique.
- When a match succeeds, the name of the last-encountered (*MARK:NAME),
- (*PRUNE:NAME), or (*THEN:NAME) on the matching path is passed back to
- the caller as described in the section entitled "Other information
- about the match" in the pcre2api documentation. Here is an example of
- pcre2test output, where the "mark" modifier requests the retrieval and
+ When a match succeeds, the name of the last-encountered (*MARK:NAME),
+ (*PRUNE:NAME), or (*THEN:NAME) on the matching path is passed back to
+ the caller as described in the section entitled "Other information
+ about the match" in the pcre2api documentation. Here is an example of
+ pcre2test output, where the "mark" modifier requests the retrieval and
outputting of (*MARK) data:
re> /X(*MARK:A)Y|X(*MARK:B)Z/mark
@@ -7826,16 +7850,16 @@
MK: B
The (*MARK) name is tagged with "MK:" in this output, and in this exam-
- ple it indicates which of the two alternatives matched. This is a more
- efficient way of obtaining this information than putting each alterna-
+ ple it indicates which of the two alternatives matched. This is a more
+ efficient way of obtaining this information than putting each alterna-
tive in its own capturing parentheses.
- If a verb with a name is encountered in a positive assertion that is
- true, the name is recorded and passed back if it is the last-encoun-
+ If a verb with a name is encountered in a positive assertion that is
+ true, the name is recorded and passed back if it is the last-encoun-
tered. This does not happen for negative assertions or failing positive
assertions.
- After a partial match or a failed match, the last encountered name in
+ After a partial match or a failed match, the last encountered name in
the entire match process is returned. For example:
re> /X(*MARK:A)Y|X(*MARK:B)Z/mark
@@ -7842,56 +7866,56 @@
data> XP
No match, mark = B
- Note that in this unanchored example the mark is retained from the
+ Note that in this unanchored example the mark is retained from the
match attempt that started at the letter "X" in the subject. Subsequent
match attempts starting at "P" and then with an empty string do not get
as far as the (*MARK) item, but nevertheless do not reset it.
- If you are interested in (*MARK) values after failed matches, you
- should probably set the PCRE2_NO_START_OPTIMIZE option (see above) to
+ If you are interested in (*MARK) values after failed matches, you
+ should probably set the PCRE2_NO_START_OPTIMIZE option (see above) to
ensure that the match is always attempted.
Verbs that act after backtracking
The following verbs do nothing when they are encountered. Matching con-
- tinues with what follows, but if there is no subsequent match, causing
- a backtrack to the verb, a failure is forced. That is, backtracking
- cannot pass to the left of the verb. However, when one of these verbs
+ tinues with what follows, but if there is no subsequent match, causing
+ a backtrack to the verb, a failure is forced. That is, backtracking
+ cannot pass to the left of the verb. However, when one of these verbs
appears inside an atomic group (which includes any group that is called
- as a subroutine) or in an assertion that is true, its effect is con-
- fined to that group, because once the group has been matched, there is
- never any backtracking into it. In this situation, backtracking has to
+ as a subroutine) or in an assertion that is true, its effect is con-
+ fined to that group, because once the group has been matched, there is
+ never any backtracking into it. In this situation, backtracking has to
jump to the left of the entire atomic group or assertion.
- These verbs differ in exactly what kind of failure occurs when back-
- tracking reaches them. The behaviour described below is what happens
- when the verb is not in a subroutine or an assertion. Subsequent sec-
+ These verbs differ in exactly what kind of failure occurs when back-
+ tracking reaches them. The behaviour described below is what happens
+ when the verb is not in a subroutine or an assertion. Subsequent sec-
tions cover these special cases.
(*COMMIT)
- This verb, which may not be followed by a name, causes the whole match
+ This verb, which may not be followed by a name, causes the whole match
to fail outright if there is a later matching failure that causes back-
- tracking to reach it. Even if the pattern is unanchored, no further
+ tracking to reach it. Even if the pattern is unanchored, no further
attempts to find a match by advancing the starting point take place. If
- (*COMMIT) is the only backtracking verb that is encountered, once it
- has been passed pcre2_match() is committed to finding a match at the
+ (*COMMIT) is the only backtracking verb that is encountered, once it
+ has been passed pcre2_match() is committed to finding a match at the
current starting point, or not at all. For example:
a+(*COMMIT)b
- This matches "xxaab" but not "aacaab". It can be thought of as a kind
+ This matches "xxaab" but not "aacaab". It can be thought of as a kind
of dynamic anchor, or "I've started, so I must finish." The name of the
- most recently passed (*MARK) in the path is passed back when (*COMMIT)
+ most recently passed (*MARK) in the path is passed back when (*COMMIT)
forces a match failure.
- If there is more than one backtracking verb in a pattern, a different
- one that follows (*COMMIT) may be triggered first, so merely passing
+ If there is more than one backtracking verb in a pattern, a different
+ one that follows (*COMMIT) may be triggered first, so merely passing
(*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
+ anchor, unless PCRE2's start-of-match optimizations are turned off, as
shown in this output from pcre2test:
re> /(*COMMIT)abc/
@@ -7902,50 +7926,50 @@
data> xyzabc
No match
- For the first pattern, PCRE2 knows that any match must start with "a",
- so the optimization skips along the subject to "a" before applying the
- pattern to the first set of data. The match attempt then succeeds. The
- second pattern disables the optimization that skips along to the first
- character. The pattern is now applied starting at "x", and so the
- (*COMMIT) causes the match to fail without trying any other starting
+ For the first pattern, PCRE2 knows that any match must start with "a",
+ so the optimization skips along the subject to "a" before applying the
+ pattern to the first set of data. The match attempt then succeeds. The
+ second pattern disables the optimization that skips along to the first
+ character. The pattern is now applied starting at "x", and so the
+ (*COMMIT) causes the match to fail without trying any other starting
points.
(*PRUNE) or (*PRUNE:NAME)
- This verb causes the match to fail at the current starting position in
+ This verb causes the match to fail at the current starting position in
the subject if there is a later matching failure that causes backtrack-
- ing to reach it. If the pattern is unanchored, the normal "bumpalong"
- advance to the next starting character then happens. Backtracking can
- occur as usual to the left of (*PRUNE), before it is reached, or when
- matching to the right of (*PRUNE), but if there is no match to the
- right, backtracking cannot cross (*PRUNE). In simple cases, the use of
- (*PRUNE) is just an alternative to an atomic group or possessive quan-
+ ing to reach it. If the pattern is unanchored, the normal "bumpalong"
+ advance to the next starting character then happens. Backtracking can
+ occur as usual to the left of (*PRUNE), before it is reached, or when
+ matching to the right of (*PRUNE), but if there is no match to the
+ right, backtracking cannot cross (*PRUNE). In simple cases, the use of
+ (*PRUNE) is just an alternative to an atomic group or possessive quan-
tifier, but there are some uses of (*PRUNE) that cannot be expressed in
- any other way. In an anchored pattern (*PRUNE) has the same effect as
+ any other way. In an anchored pattern (*PRUNE) has the same effect as
(*COMMIT).
The behaviour of (*PRUNE:NAME) is the not the same as
- (*MARK:NAME)(*PRUNE). It is like (*MARK:NAME) in that the name is
- remembered for passing back to the caller. However, (*SKIP:NAME)
- searches only for names set with (*MARK), ignoring those set by
+ (*MARK:NAME)(*PRUNE). It is like (*MARK:NAME) in that the name is
+ remembered for passing back to the caller. However, (*SKIP:NAME)
+ searches only for names set with (*MARK), ignoring those set by
(*PRUNE) or (*THEN).
(*SKIP)
- This verb, when given without a name, is like (*PRUNE), except that if
- the pattern is unanchored, the "bumpalong" advance is not to the next
+ This verb, when given without a name, is like (*PRUNE), except that if
+ the pattern is unanchored, the "bumpalong" advance is not to the next
character, but to the position in the subject where (*SKIP) was encoun-
- tered. (*SKIP) signifies that whatever text was matched leading up to
+ tered. (*SKIP) signifies that whatever text was matched leading up to
it cannot be part of a successful match. Consider:
a+(*SKIP)b
- If the subject is "aaaac...", after the first match attempt fails
- (starting at the first character in the string), the starting point
+ If the subject is "aaaac...", after the first match attempt fails
+ (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
+ 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
"c".
(*SKIP:NAME)
@@ -7952,159 +7976,159 @@
When (*SKIP) has an associated name, its behaviour is modified. When it
is triggered, the previous path through the pattern is searched for the
- most recent (*MARK) that has the same name. If one is found, the
+ most recent (*MARK) that has the same name. If one is found, the
"bumpalong" advance is to the subject position that corresponds to that
(*MARK) instead of to where (*SKIP) was encountered. If no (*MARK) with
a matching name is found, the (*SKIP) is ignored.
- Note that (*SKIP:NAME) searches only for names set by (*MARK:NAME). It
+ Note that (*SKIP:NAME) searches only for names set by (*MARK:NAME). It
ignores names that are set by (*PRUNE:NAME) or (*THEN:NAME).
(*THEN) or (*THEN:NAME)
- This verb causes a skip to the next innermost alternative when back-
- tracking reaches it. That is, it cancels any further backtracking
- within the current alternative. Its name comes from the observation
+ This verb causes a skip to the next innermost alternative when back-
+ tracking reaches it. That is, it cancels any further backtracking
+ within the current alternative. Its name comes from the observation
that it can be used for a pattern-based if-then-else block:
( COND1 (*THEN) FOO | COND2 (*THEN) BAR | COND3 (*THEN) BAZ ) ...
- If the COND1 pattern matches, FOO is tried (and possibly further items
- after the end of the group if FOO succeeds); on failure, the matcher
- 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
+ If the COND1 pattern matches, FOO is tried (and possibly further items
+ after the end of the group if FOO succeeds); on failure, the matcher
+ 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).
- The behaviour of (*THEN:NAME) is the not the same as
- (*MARK:NAME)(*THEN). It is like (*MARK:NAME) in that the name is
- remembered for passing back to the caller. However, (*SKIP:NAME)
- searches only for names set with (*MARK), ignoring those set by
+ The behaviour of (*THEN:NAME) is the not the same as
+ (*MARK:NAME)(*THEN). It is like (*MARK:NAME) in that the name is
+ remembered for passing back to the caller. However, (*SKIP:NAME)
+ searches only for names set with (*MARK), ignoring those set by
(*PRUNE) and (*THEN).
- A subpattern 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 subpattern to
- the enclosing alternative. Consider this pattern, where A, B, etc. are
- complex pattern fragments that do not contain any | characters at this
+ A subpattern 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 subpattern to
+ the enclosing alternative. Consider this pattern, where A, B, etc. are
+ complex pattern fragments that do not contain any | characters at this
level:
A (B(*THEN)C) | D
- If A and B are matched, but there is a failure in C, matching does not
+ If A and B are matched, but there is a failure in C, matching does not
backtrack into A; instead it moves to the next alternative, that is, D.
- However, if the subpattern containing (*THEN) is given an alternative,
+ However, if the subpattern containing (*THEN) is given an alternative,
it behaves differently:
A (B(*THEN)C | (*FAIL)) | D
- The effect of (*THEN) is now confined to the inner subpattern. After a
+ The effect of (*THEN) is now confined to the inner subpattern. After a
failure in C, matching moves to (*FAIL), which causes the whole subpat-
- tern to fail because there are no more alternatives to try. In this
+ tern to fail because there are no more alternatives to try. In this
case, matching does now backtrack into A.
- Note that a conditional subpattern is not considered as having two
- alternatives, because only one is ever used. In other words, the |
+ Note that a conditional subpattern is not considered as having two
+ alternatives, because only one is ever used. In other words, the |
character in a conditional subpattern has a different meaning. Ignoring
white space, consider:
^.*? (?(?=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 subpattern is
+ 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 subpattern 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
+ 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
+ The verbs just described provide four different "strengths" of control
when subsequent matching fails. (*THEN) is the weakest, carrying on the
- match at the next alternative. (*PRUNE) comes next, failing the match
- at the current starting position, but allowing an advance to the next
- character (for an unanchored pattern). (*SKIP) is similar, except that
+ match at the next alternative. (*PRUNE) comes next, failing the match
+ at the current starting position, but allowing an advance to the next
+ character (for an unanchored pattern). (*SKIP) is similar, except that
the advance may be more than one character. (*COMMIT) is the strongest,
causing the entire match to fail.
More than one backtracking verb
- If more than one backtracking verb is present in a pattern, the one
- that is backtracked onto first acts. For example, consider this pat-
+ If more than one backtracking verb is present in a pattern, the one
+ that is backtracked onto first acts. For example, consider this pat-
tern, where A, B, etc. are complex pattern fragments:
(A(*COMMIT)B(*THEN)C|ABD)
- If A matches but B fails, the backtrack to (*COMMIT) causes the entire
+ If A matches but B fails, the backtrack to (*COMMIT) causes the entire
match to fail. However, if A and B match, but C fails, the backtrack to
- (*THEN) causes the next alternative (ABD) to be tried. This behaviour
- is consistent, but is not always the same as Perl's. It means that if
- two or more backtracking verbs appear in succession, all the the last
+ (*THEN) causes the next alternative (ABD) to be tried. This behaviour
+ is consistent, but is not always the same as Perl's. It means that if
+ two or more backtracking verbs appear in succession, all the the last
of them has no effect. Consider this example:
...(*COMMIT)(*PRUNE)...
If there is a matching failure to the right, backtracking onto (*PRUNE)
- causes it to be triggered, and its action is taken. There can never be
+ causes it to be triggered, and its action is taken. There can never be
a backtrack onto (*COMMIT).
Backtracking verbs in repeated groups
- PCRE2 differs from Perl in its handling of backtracking verbs in
+ PCRE2 differs from Perl in its handling of backtracking verbs in
repeated groups. For example, consider:
/(a(*COMMIT)b)+ac/
- If the subject is "abac", Perl matches, but PCRE2 fails because the
+ If the subject is "abac", Perl matches, but PCRE2 fails because the
(*COMMIT) in the second repeat of the group acts.
Backtracking verbs in assertions
- (*FAIL) in an assertion has its normal effect: it forces an immediate
+ (*FAIL) in an assertion has its normal effect: it forces an immediate
backtrack.
(*ACCEPT) in a positive assertion causes the assertion to succeed with-
- out any further processing. In a negative assertion, (*ACCEPT) causes
+ out any further processing. In a negative assertion, (*ACCEPT) causes
the assertion to fail without any further processing.
- The other backtracking verbs are not treated specially if they appear
- in a positive assertion. In particular, (*THEN) skips to the next
- alternative in the innermost enclosing group that has alternations,
+ The other backtracking verbs are not treated specially if they appear
+ in a positive assertion. In particular, (*THEN) skips to the next
+ alternative in the innermost enclosing group that has alternations,
whether or not this is within the assertion.
- Negative assertions are, however, different, in order to ensure that
- changing a positive assertion into a negative assertion changes its
+ Negative assertions are, however, different, in order to ensure that
+ changing a positive assertion into a negative assertion changes its
result. Backtracking into (*COMMIT), (*SKIP), or (*PRUNE) causes a neg-
ative assertion to be true, without considering any further alternative
branches in the assertion. Backtracking into (*THEN) causes it to skip
- to the next enclosing alternative within the assertion (the normal be-
- haviour), but if the assertion does not have such an alternative,
+ to the next enclosing alternative within the assertion (the normal be-
+ haviour), but if the assertion does not have such an alternative,
(*THEN) behaves like (*PRUNE).
Backtracking verbs in subroutines
- These behaviours occur whether or not the subpattern is called recur-
+ These behaviours occur whether or not the subpattern is called recur-
sively. Perl's treatment of subroutines is different in some cases.
- (*FAIL) in a subpattern called as a subroutine has its normal effect:
+ (*FAIL) in a subpattern called as a subroutine has its normal effect:
it forces an immediate backtrack.
- (*ACCEPT) in a subpattern called as a subroutine causes the subroutine
- match to succeed without any further processing. Matching then contin-
+ (*ACCEPT) in a subpattern called as a subroutine causes the subroutine
+ match to succeed without any further processing. Matching then contin-
ues after the subroutine call.
(*COMMIT), (*SKIP), and (*PRUNE) in a subpattern called as a subroutine
cause the subroutine match to fail.
- (*THEN) skips to the next alternative in the innermost enclosing group
- within the subpattern that has alternatives. If there is no such group
+ (*THEN) skips to the next alternative in the innermost enclosing group
+ within the subpattern that has alternatives. If there is no such group
within the subpattern, (*THEN) causes the subroutine match to fail.
SEE ALSO
- pcre2api(3), pcre2callout(3), pcre2matching(3), pcre2syntax(3),
+ pcre2api(3), pcre2callout(3), pcre2matching(3), pcre2syntax(3),
pcre2(3).
@@ -8117,7 +8141,7 @@
REVISION
- Last updated: 16 October 2015
+ Last updated: 01 November 2015
Copyright (c) 1997-2015 University of Cambridge.
------------------------------------------------------------------------------
@@ -8539,9 +8563,11 @@
The regerror() function maps a non-zero errorcode from either regcomp()
or 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. The length of the message,
- including the zero, is limited to errbuf_size. The yield of the func-
- tion is the size of buffer needed to hold the whole message.
+ by a binary zero is placed in errbuf. If the buffer 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 needed to hold the whole
+ message, including the terminating zero. This value is greater than
+ errbuf_size if the message was truncated.
MEMORY USAGE
@@ -8561,7 +8587,7 @@
REVISION
- Last updated: 03 September 2015
+ Last updated: 30 October 2015
Copyright (c) 1997-2015 University of Cambridge.
------------------------------------------------------------------------------
@@ -8673,12 +8699,12 @@
form instead of having to compile them every time the application is
run. However, if you are using the just-in-time optimization feature,
it is not possible to save and reload the JIT data, because it is posi-
- tion-dependent. In addition, 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 endianness, pointer width and
- PCRE2_SIZE type. For example, patterns compiled on a 32-bit system
- using PCRE2's 16-bit library cannot be reloaded on a 64-bit system, nor
- can they be reloaded using the 8-bit library.
+ tion-dependent. 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 endianness, pointer width and PCRE2_SIZE type.
+ For example, patterns compiled on a 32-bit system using PCRE2's 16-bit
+ library cannot be reloaded on a 64-bit system, nor can they be reloaded
+ using the 8-bit library.
SAVING COMPILED PATTERNS
@@ -8784,10 +8810,16 @@
compiled on a system with different endianness.
Decoded patterns can be used for matching in the usual way, and must be
- freed by calling pcre2_code_free() as normal. A single copy of the
- character tables is used by all the decoded patterns. A reference count
- is used to arrange for its memory to be automatically freed when the
- last pattern is freed.
+ 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
+ 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()
+ for these patterns in different threads, you must arrange your own
+ locking, and ensure that pcre2_code_free() cannot be called by two
+ threads at the same time.
If a pattern was processed by pcre2_jit_compile() before being serial-
ized, the JIT data is discarded and so is no longer available after a
@@ -8804,7 +8836,7 @@
REVISION
- Last updated: 20 January 2015
+ Last updated: 03 November 2015
Copyright (c) 1997-2015 University of Cambridge.
------------------------------------------------------------------------------
Added: code/trunk/doc/pcre2_set_max_pattern_length.3
===================================================================
--- code/trunk/doc/pcre2_set_max_pattern_length.3 (rev 0)
+++ code/trunk/doc/pcre2_set_max_pattern_length.3 2015-11-05 17:33:39 UTC (rev 414)
@@ -0,0 +1,28 @@
+.TH PCRE2_SET_MAX_PATTERN_LENGTH 3 "05 November 2015" "PCRE2 10.21"
+.SH NAME
+PCRE2 - Perl-compatible regular expressions (revised API)
+.SH SYNOPSIS
+.rs
+.sp
+.B #include <pcre2.h>
+.PP
+.nf
+.B int pcre2_set_max_pattern_length(pcre2_compile_context *\fIccontext\fP,
+.B " PCRE2_SIZE \fIvalue\fP);"
+.fi
+.
+.SH DESCRIPTION
+.rs
+.sp
+This function sets, in a compile context, the maximum length (in code units) of
+the pattern that can be compiled. The result is always zero.
+.P
+There is a complete description of the PCRE2 native API in the
+.\" HREF
+\fBpcre2api\fP
+.\"
+page and a description of the POSIX API in the
+.\" HREF
+\fBpcre2posix\fP
+.\"
+page.
Modified: code/trunk/doc/pcre2api.3
===================================================================
--- code/trunk/doc/pcre2api.3 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/pcre2api.3 2015-11-05 17:33:39 UTC (rev 414)
@@ -1,4 +1,4 @@
-.TH PCRE2API 3 "03 November 2015" "PCRE2 10.21"
+.TH PCRE2API 3 "05 November 2015" "PCRE2 10.21"
.SH NAME
PCRE2 - Perl-compatible regular expressions (revised API)
.sp
@@ -90,6 +90,9 @@
.B int pcre2_set_character_tables(pcre2_compile_context *\fIccontext\fP,
.B " const unsigned char *\fItables\fP);"
.sp
+.B int pcre2_set_max_pattern_length(pcre2_compile_context *\fIccontext\fP,
+.B " PCRE2_SIZE \fIvalue\fP);"
+.sp
.B int pcre2_set_newline(pcre2_compile_context *\fIccontext\fP,
.B " uint32_t \fIvalue\fP);"
.sp
@@ -567,6 +570,7 @@
PCRE2's character tables
The newline character sequence
The compile time nested parentheses limit
+ The maximum length of the pattern string
An external function for stack checking
.sp
A compile context is also required if you are using custom memory management.
@@ -610,6 +614,17 @@
in the current locale.
.sp
.nf
+.B int pcre2_set_max_pattern_length(pcre2_compile_context *\fIccontext\fP,
+.B " PCRE2_SIZE \fIvalue\fP);"
+.fi
+.sp
+This sets a maximum length, in code units, for the pattern string that is to be
+compiled. 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 effectively unlimited.
+.sp
+.nf
.B int pcre2_set_newline(pcre2_compile_context *\fIccontext\fP,
.B " uint32_t \fIvalue\fP);"
.fi
@@ -3069,6 +3084,6 @@
.rs
.sp
.nf
-Last updated: 03 November 2015
+Last updated: 05 November 2015
Copyright (c) 1997-2015 University of Cambridge.
.fi
Modified: code/trunk/doc/pcre2limits.3
===================================================================
--- code/trunk/doc/pcre2limits.3 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/pcre2limits.3 2015-11-05 17:33:39 UTC (rev 414)
@@ -1,4 +1,4 @@
-.TH PCRE2LIMITS 3 "03 November 2015" "PCRE2 10.21"
+.TH PCRE2LIMITS 3 "05 November 2015" "PCRE2 10.21"
.SH NAME
PCRE2 - Perl-compatible regular expressions (revised API)
.SH "SIZE AND OTHER LIMITATIONS"
@@ -20,6 +20,10 @@
However, the speed of execution is slower. In the 32-bit library, the internal
linkage size is always 4.
.P
+The maximum length of a source pattern string is essentially unlimited; it is
+the largest number a PCRE2_SIZE variable can hold. However, the program that
+calls \fBpcre2_compile()\fP can specify a smaller limit.
+.P
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
@@ -71,6 +75,6 @@
.rs
.sp
.nf
-Last updated: 03 November 2015
+Last updated: 05 November 2015
Copyright (c) 1997-2015 University of Cambridge.
.fi
Modified: code/trunk/doc/pcre2test.1
===================================================================
--- code/trunk/doc/pcre2test.1 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/pcre2test.1 2015-11-05 17:33:39 UTC (rev 414)
@@ -1,4 +1,4 @@
-.TH PCRE2TEST 1 "30 October 2015" "PCRE 10.21"
+.TH PCRE2TEST 1 "05 November 2015" "PCRE 10.21"
.SH NAME
pcre2test - a program for testing Perl-compatible regular expressions.
.SH SYNOPSIS
@@ -528,6 +528,7 @@
jitfast use JIT fast path
jitverify verify JIT use
locale=<name> use this locale
+ max_pattern_length=<n> set the maximum pattern length
memory show memory used
newline=<type> set newline type
null_context compile with a NULL context
@@ -767,6 +768,15 @@
suite.
.
.
+.SS "Limiting the pattern length"
+.rs
+.sp
+The \fBmax_pattern_length\fP modifier sets a limit, in code units, to the
+length of pattern that \fBpcre2_compile()\fP will accept. Breaching the limit
+causes a compilation error. The default is the largest number a PCRE2_SIZE
+variable can hold (essentially unlimited).
+.
+.
.SS "Using the POSIX wrapper API"
.rs
.sp
@@ -1596,6 +1606,6 @@
.rs
.sp
.nf
-Last updated: 30 October 2015
+Last updated: 05 November 2015
Copyright (c) 1997-2015 University of Cambridge.
.fi
Modified: code/trunk/doc/pcre2test.txt
===================================================================
--- code/trunk/doc/pcre2test.txt 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/doc/pcre2test.txt 2015-11-05 17:33:39 UTC (rev 414)
@@ -209,107 +209,108 @@
or \r\n, etc., depending on the newline setting) in a single line of
input to encode the newline sequences. There is no limit on the length
of subject lines; the input buffer is automatically extended if it is
- too small. There is a replication feature that makes it possible to
- generate long subject lines without having to supply them explicitly.
+ too small. There are replication features that makes it possible to
+ generate long repetitive pattern or subject lines without having to
+ 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
+ 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.
COMMAND LINES
- In between sets of test data, a line that begins with # is interpreted
+ In between sets of test data, a line that begins with # is interpreted
as a command line. If the first character is followed by white space or
- an exclamation mark, the line is treated as a comment, and ignored.
+ an exclamation mark, the line is treated as a comment, and ignored.
Otherwise, the following commands are recognized:
#forbid_utf
- Subsequent patterns automatically have the PCRE2_NEVER_UTF and
- PCRE2_NEVER_UCP options set, which locks out the use of the PCRE2_UTF
- and PCRE2_UCP options and the use of (*UTF) and (*UCP) at the start of
- patterns. This command also forces an error if a subsequent pattern
- contains any occurrences of \P, \p, or \X, which are still supported
- when PCRE2_UTF is not set, but which require Unicode property support
+ Subsequent patterns automatically have the PCRE2_NEVER_UTF and
+ PCRE2_NEVER_UCP options set, which locks out the use of the PCRE2_UTF
+ and PCRE2_UCP options and the use of (*UTF) and (*UCP) at the start of
+ patterns. This command also forces an error if a subsequent pattern
+ contains any occurrences of \P, \p, or \X, which are still supported
+ when PCRE2_UTF is not set, but which require Unicode property support
to be included in the library.
- This is a trigger guard that is used in test files to ensure that UTF
- or Unicode property tests are not accidentally added to files that are
- used when Unicode support is not included in the library. Setting
- PCRE2_NEVER_UTF and PCRE2_NEVER_UCP as a default can also be obtained
- by the use of #pattern; the difference is that #forbid_utf cannot be
- unset, and the automatic options are not displayed in pattern informa-
+ This is a trigger guard that is used in test files to ensure that UTF
+ or Unicode property tests are not accidentally added to files that are
+ used when Unicode support is not included in the library. Setting
+ PCRE2_NEVER_UTF and PCRE2_NEVER_UCP as a default can also be obtained
+ by the use of #pattern; the difference is that #forbid_utf cannot be
+ unset, and the automatic options are not displayed in pattern informa-
tion, to avoid cluttering up test output.
#load <filename>
This command is used to load a set of precompiled patterns from a file,
- as described in the section entitled "Saving and restoring compiled
+ as described in the section entitled "Saving and restoring compiled
patterns" below.
#newline_default [<newline-list>]
- When PCRE2 is built, a default newline convention can be specified.
- This determines which characters and/or character pairs are recognized
+ When PCRE2 is built, a default newline convention can be specified.
+ This determines which characters and/or character pairs are recognized
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
+ 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-
piled with either CR or CRLF as the default newline.
The #newline_default command specifies a list of newline types that are
- acceptable as the default. The types must be one of CR, LF, CRLF, ANY-
+ acceptable as the default. The types must be one of CR, LF, CRLF, ANY-
CRLF, or ANY (in upper or lower case), for example:
#newline_default LF Any anyCRLF
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
+ 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
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
+ 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
modifier is used when #newline_default would set a default for the non-
POSIX API.
#pattern <modifier-list>
- This command sets a default modifier list that applies to all subse-
+ This command sets a default modifier list that applies to all subse-
quent patterns. Modifiers on a pattern can change these settings.
#perltest
- The appearance of this line causes all subsequent modifier settings to
+ 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, none of the other 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
+ to confirm that Perl gives the same results as PCRE2. Also, apart from
+ comment lines, none of the other 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.
#pop [<modifiers>]
- This command is used to manipulate the stack of compiled patterns, as
- described in the section entitled "Saving and restoring compiled pat-
+ This command is used to manipulate the stack of compiled patterns, as
+ described in the section entitled "Saving and restoring compiled pat-
terns" below.
#save <filename>
- This command is used to save a set of compiled patterns to a file, as
- described in the section entitled "Saving and restoring compiled pat-
+ This command is used to save a set of compiled patterns to a file, as
+ described in the section entitled "Saving and restoring compiled pat-
terns" below.
#subject <modifier-list>
- This command sets a default modifier list that applies to all subse-
- quent subject lines. Modifiers on a subject line can change these set-
+ This command sets a default modifier list that applies to all subse-
+ quent subject lines. Modifiers on a subject line can change these set-
tings.
@@ -317,58 +318,58 @@
Modifier lists are used with both pattern and subject lines. Items in a
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
+ 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
- value, for example, "offset=12". Values cannot contain comma charac-
- ters, but may contain spaces. Modifiers that do not take values may be
+ "anchored", 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.
A few of the more common modifiers can also be specified as single let-
- ters, for example "i" for "caseless". In documentation, following the
+ ters, for example "i" for "caseless". In documentation, following the
Perl convention, these are written with a slash ("the /i modifier") for
- clarity. Abbreviated modifiers must all be concatenated in the first
- item of a modifier list. If the first item is not recognized as a long
- modifier name, it is interpreted as a sequence of these abbreviations.
+ clarity. Abbreviated modifiers must all be concatenated in the first
+ item of a modifier list. If the first item is not recognized as a long
+ modifier name, it is interpreted as a sequence of these abbreviations.
For example:
/abc/ig,newline=cr,jit=3
- This is a pattern line whose modifier list starts with two one-letter
- modifiers (/i and /g). The lower-case abbreviated modifiers are the
+ This is a pattern line whose modifier list starts with two one-letter
+ modifiers (/i and /g). The lower-case abbreviated modifiers are the
same as used in Perl.
PATTERN SYNTAX
- A pattern line must start with one of the following characters (common
+ A pattern line must start with one of the following characters (common
symbols, excluding pattern meta-characters):
/ ! " ' ` - = _ : ; , % & @ ~
- This is interpreted as the pattern's delimiter. A regular expression
- may be continued over several input lines, in which case the newline
+ This is interpreted as the pattern's delimiter. A regular expression
+ may be continued over several input lines, in which case the newline
characters are included within it. It is possible to include the delim-
iter within the pattern by escaping it with a backslash, for example
/abc\/def/
- If you do this, the escape and the delimiter form part of the pattern,
+ If you do this, the escape and the delimiter form part of the pattern,
but since the delimiters are all non-alphanumeric, this does not affect
- its interpretation. If the terminating delimiter is immediately fol-
+ its interpretation. If the terminating delimiter is immediately fol-
lowed by a backslash, for example,
/abc/\
- then a backslash is added to the end of the pattern. This is done to
- provide a way of testing the error condition that arises if a pattern
+ then a backslash is added to the end of the pattern. This is done to
+ provide a way of testing the error condition that arises if a pattern
finishes with a backslash, because
/abc\/
- is interpreted as the first line of a pattern that starts with "abc/",
- causing pcre2test to read the next line as a continuation of the regu-
+ is interpreted as the first line of a pattern that starts with "abc/",
+ causing pcre2test to read the next line as a continuation of the regu-
lar expression.
A pattern can be followed by a modifier list (details below).
@@ -376,7 +377,7 @@
SUBJECT LINE SYNTAX
- Before each subject line is passed to pcre2_match() or
+ Before each subject line is passed to pcre2_match() or
pcre2_dfa_match(), leading and trailing white space is removed, and the
line is scanned for backslash escapes. The following provide a means of
encoding non-printing characters in a visible way:
@@ -396,15 +397,15 @@
\x{hh...} hexadecimal character (any number of hex digits)
The use of \x{hh...} is not dependent on the use of the utf modifier on
- the pattern. It is recognized always. There may be any number of hexa-
- decimal digits inside the braces; invalid values provoke error mes-
+ the pattern. It is recognized always. There may be any number of hexa-
+ decimal digits inside the braces; invalid values provoke error mes-
sages.
- Note that \xhh specifies one byte rather than one character in UTF-8
- mode; this makes it possible to construct invalid UTF-8 sequences for
- testing purposes. On the other hand, \x{hh} is interpreted as a UTF-8
- character in UTF-8 mode, generating more than one byte if the value is
- greater than 127. When testing the 8-bit library not in UTF-8 mode,
+ Note that \xhh specifies one byte rather than one character in UTF-8
+ mode; this makes it possible to construct invalid UTF-8 sequences for
+ testing purposes. On the other hand, \x{hh} is interpreted as a UTF-8
+ character in UTF-8 mode, generating more than one byte if the value is
+ greater than 127. When testing the 8-bit library not in UTF-8 mode,
\x{hh} generates one byte for values less than 256, and causes an error
for greater values.
@@ -411,8 +412,8 @@
In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
possible to construct invalid UTF-16 sequences for testing purposes.
- In UTF-32 mode, all 4- to 8-digit \x{...} values are accepted. This
- makes it possible to construct invalid UTF-32 sequences for testing
+ In UTF-32 mode, all 4- to 8-digit \x{...} values are accepted. This
+ makes it possible to construct invalid UTF-32 sequences for testing
purposes.
There is a special backslash sequence that specifies replication of one
@@ -420,45 +421,45 @@
\[<characters>]{<count>}
- This makes it possible to test long strings without having to provide
+ This makes it possible to test long strings without having to provide
them as part of the file. For example:
\[abc]{4}
- is converted to "abcabcabcabc". This feature does not support nesting.
+ is converted to "abcabcabcabc". This feature does not support nesting.
To include a closing square bracket in the characters, code it as \x5D.
- A backslash followed by an equals sign marks the end of the subject
+ A backslash followed by an equals sign marks the end of the subject
string and the start of a modifier list. For example:
abc\=notbol,notempty
- If the subject string is empty and \= is followed by whitespace, the
- line is treated as a comment line, and is not used for matching. For
+ If the subject string is empty and \= is followed by whitespace, the
+ line is treated as a comment line, and is not used for matching. For
example:
\= This is a comment.
abc\= This is an invalid modifier list.
- A backslash followed by any other non-alphanumeric character just
+ A backslash followed by any other non-alphanumeric character just
escapes 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
+ 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
data input.
PATTERN MODIFIERS
- There are three types of modifier that can appear in pattern lines, two
- of which may also be used in a #pattern command. A pattern's modifier
- list can add to or override default modifiers that were set by a previ-
- ous #pattern command.
+ There are several types of modifier that can appear in pattern lines.
+ Except where noted below, they may also be used in #pattern commands. A
+ pattern's modifier list can add to or override default modifiers that
+ were set by a previous #pattern command.
Setting compilation options
- The following modifiers set options for pcre2_compile(). The most com-
- mon ones have single-letter abbreviations. See pcre2api for a descrip-
+ The following modifiers set options for pcre2_compile(). The most com-
+ mon ones have single-letter abbreviations. See pcre2api for a descrip-
tion of their effects.
allow_empty_class set PCRE2_ALLOW_EMPTY_CLASS
@@ -489,13 +490,13 @@
utf set PCRE2_UTF
As well as turning on the PCRE2_UTF option, the utf modifier causes all
- non-printing characters in output strings to be printed using the
- \x{hh...} notation. Otherwise, those less than 0x100 are output in hex
+ non-printing characters in output strings to be printed using the
+ \x{hh...} notation. Otherwise, those less than 0x100 are output in hex
without the curly brackets.
Setting compilation controls
- The following modifiers affect the compilation process or request
+ The following modifiers affect the compilation process or request
information about the pattern:
bsr=[anycrlf|unicode] specify \R handling
@@ -509,6 +510,7 @@
jitfast use JIT fast path
jitverify verify JIT use
locale=<name> use this locale
+ max_pattern_length=<n> set the maximum pattern length
memory show memory used
newline=<type> set newline type
null_context compile with a NULL context
@@ -522,34 +524,34 @@
Newline and \R handling
- The bsr modifier specifies what \R in a pattern should match. If it is
- set to "anycrlf", \R matches CR, LF, or CRLF only. If it is set to
- "unicode", \R matches any Unicode newline sequence. The default is
+ The bsr modifier specifies what \R in a pattern should match. If it is
+ set to "anycrlf", \R matches CR, LF, or CRLF only. If it is set to
+ "unicode", \R matches any Unicode newline sequence. The default is
specified when PCRE2 is built, with the default default being Unicode.
- The newline modifier specifies which characters are to be interpreted
+ The newline modifier specifies which characters are to be interpreted
as newlines, both in the pattern and in subject lines. The type must be
one of CR, LF, CRLF, ANYCRLF, or ANY (in upper or lower case).
Information about a pattern
- The debug modifier is a shorthand for info,fullbincode, requesting all
+ The debug modifier is a shorthand for info,fullbincode, requesting all
available information.
The bincode modifier causes a representation of the compiled code to be
- output after compilation. This information does not contain length and
+ output after compilation. This information does not contain length and
offset values, which ensures that the same output is generated for dif-
- ferent internal link sizes and different code unit widths. By using
- bincode, the same regression tests can be used in different environ-
+ ferent internal link sizes and different code unit widths. By using
+ bincode, the same regression tests can be used in different environ-
ments.
- The fullbincode modifier, by contrast, does include length and offset
- values. This is used in a few special tests that run only for specific
+ The fullbincode modifier, by contrast, does include length and offset
+ values. This is used in a few special tests that run only for specific
code unit widths and link sizes, and is also useful for one-off tests.
- The info modifier requests information about the compiled pattern
- (whether it is anchored, has a fixed first character, and so on). The
- information is obtained from the pcre2_pattern_info() function. Here
+ The info modifier requests information about the compiled pattern
+ (whether it is anchored, has a fixed first character, and so on). The
+ information is obtained from the pcre2_pattern_info() function. Here
are some typical examples:
re> /(?i)(^a|^b)/m,info
@@ -567,17 +569,17 @@
Last code unit = 'c' (caseless)
Subject length lower bound = 3
- "Compile options" are those specified by modifiers; "overall options"
- have added options that are taken or deduced from the pattern. If both
- sets of options are the same, just a single "options" line is output;
- if there are no options, the line is omitted. "First code unit" is
- where any match must start; if there is more than one they are listed
- as "starting code units". "Last code unit" is the last literal code
- unit that must be present in any match. This is not necessarily the
- last character. These lines are omitted if no starting or ending code
+ "Compile options" are those specified by modifiers; "overall options"
+ have added options that are taken or deduced from the pattern. If both
+ sets of options are the same, just a single "options" line is output;
+ if there are no options, the line is omitted. "First code unit" is
+ where any match must start; if there is more than one they are listed
+ as "starting code units". "Last code unit" is the last literal code
+ unit that must be present in any match. This is not necessarily the
+ last character. These lines are omitted if no starting or ending code
units are recorded.
- The callout_info modifier requests information about all the callouts
+ The callout_info modifier requests information about all the callouts
in the pattern. A list of them is output at the end of any other infor-
mation that is requested. For each callout, either its number or string
is given, followed by the item that follows it in the pattern.
@@ -584,40 +586,64 @@
Passing a NULL context
- Normally, pcre2test passes a context block to pcre2_compile(). If the
- null_context modifier is set, however, NULL is passed. This is for
- testing that pcre2_compile() behaves correctly in this case (it uses
+ Normally, pcre2test passes a context block to pcre2_compile(). If the
+ null_context modifier is set, however, NULL is passed. This is for
+ testing that pcre2_compile() behaves correctly in this case (it uses
default values).
Specifying a pattern in hex
The hex modifier specifies that the characters of the pattern are to be
- interpreted as pairs of hexadecimal digits. White space is permitted
+ interpreted as pairs of hexadecimal digits. White space is permitted
between pairs. For example:
/ab 32 59/hex
- This feature is provided as a way of creating patterns that contain
- binary zero and other non-printing characters. By default, pcre2test
- passes patterns as zero-terminated strings to pcre2_compile(), giving
+ This feature is provided as a way of creating patterns that contain
+ binary zero and other non-printing characters. By default, pcre2test
+ passes patterns as zero-terminated strings to pcre2_compile(), giving
the length as PCRE2_ZERO_TERMINATED. However, for patterns specified in
hexadecimal, the actual length of the pattern is passed.
+ Generating long repetitive patterns
+
+ Some tests use long patterns that are very repetitive. Instead of cre-
+ ating a very long input line for such a pattern, you can use a special
+ repetition feature, similar to the one described for subject lines
+ above. If the expand modifier is present on a pattern, parts of the
+ pattern that have the form
+
+ \[<characters>]{<count>}
+
+ are expanded before the pattern is passed to pcre2_compile(). For exam-
+ ple, \[AB]{6000} is expanded to "ABAB..." 6000 times. This construction
+ cannot be nested. An initial "\[" sequence is recognized only if "]{"
+ followed by decimal digits and "}" is found later in the pattern. If
+ not, the characters remain in the pattern unaltered.
+
+ If part of an expanded pattern looks like an expansion, but is really
+ part of the actual pattern, unwanted expansion can be avoided by giving
+ two values in the quantifier. For example, \[AB]{6000,6000} is not rec-
+ ognized as an expansion item.
+
+ If the info modifier is set on an expanded pattern, the result of the
+ expansion is included in the information that is output.
+
JIT compilation
- Just-in-time (JIT) compiling is a heavyweight optimization that can
- greatly speed up pattern matching. See the pcre2jit documentation for
- details. JIT compiling happens, optionally, after a pattern has been
- successfully compiled into an internal form. The JIT compiler converts
+ Just-in-time (JIT) compiling is a heavyweight optimization that can
+ greatly speed up pattern matching. See the pcre2jit documentation for
+ details. JIT compiling happens, optionally, after a pattern has been
+ successfully compiled into an internal form. The JIT compiler converts
this to optimized machine code. It needs to know whether the match-time
options PCRE2_PARTIAL_HARD and PCRE2_PARTIAL_SOFT are going to be used,
- because different code is generated for the different cases. See the
- partial modifier in "Subject Modifiers" below for details of how these
+ because different code is generated for the different cases. See the
+ 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
+ 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
- 7. The three bits that make up the number specify which of the three
+ 7. The three bits that make up the number specify which of the three
JIT operating modes are to be compiled:
1 compile JIT code for non-partial matching
@@ -634,31 +660,31 @@
6 soft and hard partial matching only
7 all three modes
- If no number is given, 7 is assumed. The phrase "partial matching"
+ If no number is given, 7 is assumed. The phrase "partial matching"
means a call to pcre2_match() with either the PCRE2_PARTIAL_SOFT or the
- PCRE2_PARTIAL_HARD option set. Note that such a call may return a com-
+ PCRE2_PARTIAL_HARD option set. Note that such a call may return a com-
plete match; the options enable the possibility of a partial match, but
- do not require it. Note also that if you request JIT compilation only
- for partial matching (for example, /jit=2) but do not set the partial
- modifier on a subject line, that match will not use JIT code because
+ do not require it. Note also that if you request JIT compilation only
+ for partial matching (for example, /jit=2) but do not set the partial
+ modifier on a subject line, that match will not use JIT code because
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
- pcre2jit documentation. See also the jitstack modifier below for a way
+ 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
+ pcre2jit documentation. See also the jitstack modifier below for a way
of setting the size of the JIT stack.
- If the jitfast modifier is specified, matching is done using the JIT
- "fast path" interface, pcre2_jit_match(), which skips some of the san-
- ity checks that are done by pcre2_match(), and of course does not work
- when JIT is not supported. If jitfast is specified without jit, jit=7
+ If the jitfast modifier is specified, matching is done using the JIT
+ "fast path" interface, pcre2_jit_match(), which skips some of the san-
+ ity checks that are done by pcre2_match(), and of course does not work
+ when JIT is not supported. If jitfast is specified without jit, jit=7
is assumed.
- If the jitverify modifier is specified, information about the compiled
- pattern shows whether JIT compilation was or was not successful. If
- jitverify is specified without jit, jit=7 is assumed. If JIT compila-
- tion is successful when jitverify is set, the text "(JIT)" is added to
+ If the jitverify modifier is specified, information about the compiled
+ pattern shows whether JIT compilation was or was not successful. If
+ jitverify is specified without jit, jit=7 is assumed. If JIT compila-
+ tion is successful when jitverify is set, the text "(JIT)" is added to
the first output line after a match or non match when JIT-compiled code
was actually used in the match.
@@ -669,18 +695,18 @@
/pattern/locale=fr_FR
The given locale is set, pcre2_maketables() is called to build a set of
- character tables for the locale, and this is then passed to pcre2_com-
- pile() when compiling the regular expression. The same tables are used
+ character tables for the locale, and this is then passed to pcre2_com-
+ pile() when compiling the regular expression. The same tables are used
when matching the following subject lines. The /locale modifier applies
only to the pattern on which it appears, but can be given in a #pattern
- command if a default is needed. Setting a locale and alternate charac-
+ command if a default is needed. Setting a locale and alternate charac-
ter tables are mutually exclusive.
Showing pattern memory
- The /memory modifier causes the size in bytes of the memory used to
- hold the compiled pattern to be output. This does not include the size
- of the pcre2_code block; it is just the actual compiled data. If the
+ The /memory modifier causes the size in bytes of the memory used to
+ hold the compiled pattern to be output. This does not include the size
+ of the pcre2_code block; it is just the actual compiled data. If the
pattern is subsequently passed to the JIT compiler, the size of the JIT
compiled code is also output. Here is an example:
@@ -691,12 +717,19 @@
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
- pcre2test sets its own default of 220, which is required for running
+ 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
+ pcre2test sets its own default of 220, which is required for running
the standard test suite.
+ Limiting the pattern length
+
+ The max_pattern_length modifier sets a limit, in code units, to the
+ length of pattern that pcre2_compile() will accept. Breaching the limit
+ causes a compilation error. The default is the largest number a
+ PCRE2_SIZE variable can hold (essentially unlimited).
+
Using the POSIX wrapper API
The /posix modifier causes pcre2test to call PCRE2 via the POSIX wrap-
@@ -714,6 +747,16 @@
ucp REG_UCP ) the POSIX standard
utf REG_UTF8 )
+ The regerror_buffsize modifier specifies a size for the error buffer
+ that is passed to regerror() in the event of a compilation error. For
+ example:
+
+ /abc/posix,regerror_buffsize=20
+
+ This provides a means of testing the behaviour of regerror() when the
+ 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 cause an error.
@@ -751,7 +794,8 @@
The following modifiers are really subject modifiers, and are described
below. However, they may be included in a pattern's modifier list, in
which case they are applied to every subject line that is processed
- with that pattern. They do not affect the compilation process.
+ with that pattern. They may not appear in #pattern commands. These mod-
+ ifiers do not affect the compilation process.
aftertext show text after match
allaftertext show text after captures
@@ -762,20 +806,20 @@
replace=<string> specify a replacement string
startchar show starting character when relevant
- These modifiers may not appear in a #pattern command. If you want them
+ These modifiers may not appear in a #pattern command. If you want them
as defaults, set them in a #subject command.
Saving a compiled pattern
- When a pattern with the push modifier is successfully compiled, it is
- pushed onto a stack of compiled patterns, and pcre2test expects the
- next line to contain a new pattern (or a command) instead of a subject
+ When a pattern with the push modifier is successfully compiled, it is
+ pushed onto a stack of compiled patterns, and pcre2test expects the
+ next line to contain a new pattern (or a command) instead of a subject
line. This facility is used when saving compiled patterns to a file, as
- described in the section entitled "Saving and restoring compiled pat-
+ described in the section entitled "Saving and restoring compiled pat-
terns" below. The push modifier is incompatible with compilation modi-
fiers such as global that act at match time. Any that are specified are
- ignored, with a warning message, except for replace, which causes an
- error. Note that, jitverify, which is allowed, does not carry through
+ ignored, 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 this pattern.
@@ -786,7 +830,7 @@
Setting match options
- The following modifiers set options for pcre2_match() or
+ The following modifiers set options for pcre2_match() or
pcre2_dfa_match(). See pcreapi for a description of their effects.
anchored set PCRE2_ANCHORED
@@ -800,20 +844,20 @@
partial_hard (or ph) set PCRE2_PARTIAL_HARD
partial_soft (or ps) set PCRE2_PARTIAL_SOFT
- The partial matching modifiers are provided with abbreviations because
+ The partial matching modifiers are provided with abbreviations because
they appear frequently in tests.
- If the /posix modifier was present on the pattern, causing the POSIX
+ If the /posix modifier was present on the pattern, causing the POSIX
wrapper API to be used, the only option-setting modifiers that have any
- effect are notbol, notempty, and noteol, causing REG_NOTBOL,
- REG_NOTEMPTY, and REG_NOTEOL, respectively, to be passed to regexec().
+ effect are notbol, notempty, and noteol, causing REG_NOTBOL,
+ REG_NOTEMPTY, and REG_NOTEOL, respectively, to be passed to regexec().
Any other modifiers cause an error.
Setting match controls
- The following modifiers affect the matching process or request addi-
- tional information. Some of them may also be specified on a pattern
- line (see above), in which case they apply to every subject line that
+ The following modifiers affect the matching process or request addi-
+ tional information. Some of them may also be specified on a pattern
+ line (see above), in which case they apply to every subject line that
is matched against that pattern.
aftertext show text after match
@@ -848,23 +892,23 @@
Showing more text
- The aftertext modifier requests that as well as outputting the part of
+ The aftertext modifier requests that as well as outputting the part of
the subject string that matched the entire pattern, pcre2test should in
addition output the remainder of the subject string. This is useful for
tests where the subject contains multiple copies of the same substring.
- The allaftertext modifier requests the same action for captured sub-
+ The allaftertext modifier requests the same action for captured sub-
strings as well as the main matched substring. In each case the remain-
der is output on the following line with a plus character following the
capture number.
- 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
+ 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
+ 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:
re> /(?<=pqr)abc(?=xyz)/
@@ -872,16 +916,16 @@
0: pqrabcxyz
<<< >>>
- This shows that the matched string is "abc", with the preceding and
- following strings "pqr" and "xyz" having been consulted during the
+ This shows that the matched string is "abc", with the preceding and
+ following strings "pqr" and "xyz" having been consulted during the
match (when processing the assertions).
- The startchar modifier requests that the starting character for the
- match be indicated, if it is different to the start of the matched
+ The startchar modifier requests that the starting character for the
+ match be indicated, if it is different to the start of the matched
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
+ is displayed from the starting character instead of from the match
+ point, with circumflex characters under the earlier characters. For
example:
re> /abc\Kxyz/
@@ -889,7 +933,7 @@
0: abcxyz
^^^
- Unlike allusedtext, the startchar modifier can be used with JIT. How-
+ Unlike allusedtext, the startchar modifier can be used with JIT. How-
ever, these two modifiers are mutually exclusive.
Showing the value of all capture groups
@@ -897,88 +941,88 @@
The allcaptures modifier requests that the values of all potential cap-
tured parentheses be output after a match. By default, only those up to
the highest one actually used in the match are output (corresponding to
- the return code from pcre2_match()). Groups that did not take part in
+ the return code from pcre2_match()). Groups that did not take part in
the match are output as "<unset>".
Testing callouts
- A callout function is supplied when pcre2test calls the library match-
- ing functions, unless callout_none is specified. If callout_capture is
+ A callout function is supplied when pcre2test calls the library match-
+ ing functions, unless callout_none is specified. If callout_capture is
set, the current captured groups are output when a callout occurs.
- The callout_fail modifier can be given one or two numbers. If there is
+ The callout_fail modifier can be given one or two numbers. If there is
only one number, 1 is returned instead of 0 when a callout of that num-
- ber is reached. If two numbers are given, 1 is returned when callout
+ ber is reached. If two numbers are given, 1 is returned when callout
<n> is reached for the <m>th time. Note that callouts with string argu-
- ments are always given the number zero. See "Callouts" below for a
+ ments are always given the number zero. See "Callouts" below for a
description of the output when a callout it taken.
- The callout_data modifier can be given an unsigned or a negative num-
- ber. This is set as the "user data" that is passed to the matching
- function, and passed back when the callout function is invoked. Any
- value other than zero is used as a return from pcre2test's callout
+ The callout_data modifier can be given an unsigned or a negative num-
+ ber. This is set as the "user data" that is passed to the matching
+ function, and passed back when the callout function is invoked. Any
+ value other than zero is used as a return from pcre2test's callout
function.
Finding all matches in a string
Searching for all possible matches within a subject can be requested by
- the global or /altglobal modifier. After finding a match, the matching
- function is called again to search the remainder of the subject. The
- difference between global and altglobal is that the former uses the
- start_offset argument to pcre2_match() or pcre2_dfa_match() to start
- searching at a new point within the entire string (which is what Perl
+ the global or /altglobal modifier. After finding a match, the matching
+ function is called again to search the remainder of the subject. The
+ difference between global and altglobal is that the former uses the
+ start_offset argument to pcre2_match() or pcre2_dfa_match() to start
+ searching at a new point within the entire string (which is what Perl
does), whereas the latter passes over a shortened subject. This makes a
difference to the matching process if the pattern begins with a lookbe-
hind assertion (including \b or \B).
- If an empty string is matched, the next match is done with the
+ 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
+ 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.
Testing substring extraction functions
- The copy and get modifiers can be used to test the pcre2_sub-
+ The copy and get modifiers can be used to test the pcre2_sub-
string_copy_xxx() and pcre2_substring_get_xxx() functions. They can be
- given more than once, and each can specify a group name or number, for
+ given more than once, and each can specify a group name or number, for
example:
abcd\=copy=1,copy=3,get=G1
- If the #subject command is used to set default copy and/or get lists,
- these can be unset by specifying a negative number to cancel all num-
+ If the #subject command is used to set default copy and/or get lists,
+ these can be unset by specifying a negative number to cancel all num-
bered groups and an empty name to cancel all named groups.
- The getall modifier tests pcre2_substring_list_get(), which extracts
+ The getall modifier tests pcre2_substring_list_get(), which extracts
all captured substrings.
- If the subject line is successfully matched, the substrings extracted
- by the convenience functions are output with C, G, or L after the
- string number instead of a colon. This is in addition to the normal
- full list. The string length (that is, the return from the extraction
+ If the subject line is successfully matched, the substrings extracted
+ by the convenience functions are output with C, G, or L after the
+ string number instead of a colon. This is in addition to the normal
+ full list. The string length (that is, the return from the extraction
function) is given in parentheses after each substring, followed by the
name when the extraction was by name.
Testing the substitution function
- If the replace modifier is set, the pcre2_substitute() function is
- called instead of one of the matching functions. Unlike subject
- strings, pcre2test does not process replacement strings for escape
+ If the replace modifier is set, the pcre2_substitute() function is
+ called instead of one of the matching functions. Unlike subject
+ strings, pcre2test does not process replacement strings for escape
sequences. In UTF mode, a replacement string is checked to see if it is
a valid UTF-8 string. If so, it is correctly converted to a UTF string
- of the appropriate code unit width. If it is not a valid UTF-8 string,
+ of the appropriate code unit width. If it is not a valid UTF-8 string,
the individual code units are copied directly. This provides a means of
passing an invalid UTF-8 string for testing purposes.
- If the global modifier is set, PCRE2_SUBSTITUTE_GLOBAL is passed to
+ If the global modifier is set, PCRE2_SUBSTITUTE_GLOBAL is passed to
pcre2_substitute(). After a successful substitution, the modified
- string is output, preceded by the number of replacements. This may be
- zero if there were no matches. Here is a simple example of a substitu-
+ string is output, preceded by the number of replacements. This may be
+ zero if there were no matches. Here is a simple example of a substitu-
tion test:
/abc/replace=xxx
@@ -987,11 +1031,11 @@
=abc=abc=\=global
2: =xxx=xxx=
- Subject and replacement strings should be kept relatively short 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 num-
- ber in square brackets, that number is passed to pcre2_substitute() as
- the size of the output buffer, with the replacement string starting at
+ Subject and replacement strings should be kept relatively short 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 num-
+ ber 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 that tests the edge case:
/abc/
@@ -1001,13 +1045,13 @@
Failed: error -47: no more memory
A replacement string is ignored with POSIX and DFA matching. Specifying
- partial matching provokes an error return ("bad option value") from
+ partial matching provokes an error return ("bad option value") from
pcre2_substitute().
Setting the JIT stack size
- The jitstack modifier provides a way of setting the maximum stack size
- that is used by the just-in-time optimization code. It is ignored if
+ The jitstack modifier provides a way of setting the maximum stack size
+ that is used by the just-in-time optimization code. It is ignored if
JIT optimization is not being used. The value is a number of kilobytes.
Providing a stack that is larger than the default 32K is necessary only
for very complicated patterns.
@@ -1014,29 +1058,29 @@
Setting match and recursion limits
- The match_limit and recursion_limit modifiers set the appropriate lim-
+ The match_limit and recursion_limit modifiers set the appropriate lim-
its in the match context. These values are ignored when the find_limits
modifier is specified.
Finding minimum limits
- If the find_limits modifier is present, pcre2test calls pcre2_match()
- several times, setting different values in the match context via
- pcre2_set_match_limit() and pcre2_set_recursion_limit() until it finds
- the minimum values for each parameter that allow pcre2_match() to com-
+ If the find_limits modifier is present, pcre2test calls pcre2_match()
+ several times, setting different values in the match context via
+ pcre2_set_match_limit() and pcre2_set_recursion_limit() until it finds
+ the minimum values for each parameter that allow pcre2_match() to com-
plete without error.
If JIT is being used, only the match limit is relevant. If DFA matching
- is being used, neither limit is relevant, and this modifier is ignored
+ is being used, neither limit is relevant, and this modifier is ignored
(with a warning message).
- The match_limit number is a measure of the amount of backtracking that
- takes place, and learning the minimum value can be instructive. For
- most simple matches, the number is quite small, but for patterns with
- very large numbers of matching possibilities, it can become large very
- quickly with increasing length of subject string. The
- match_limit_recursion number is a measure of how much stack (or, if
- PCRE2 is compiled with NO_RECURSE, how much heap) memory is needed to
+ The match_limit number is a measure of the amount of backtracking that
+ takes place, and learning the minimum value can be instructive. For
+ most simple matches, the number is quite small, but for patterns with
+ very large numbers of matching possibilities, it can become large very
+ quickly with increasing length of subject string. The
+ match_limit_recursion number is a measure of how much stack (or, if
+ PCRE2 is compiled with NO_RECURSE, how much heap) memory is needed to
complete the match attempt.
Showing MARK names
@@ -1043,42 +1087,42 @@
The mark modifier causes the names from backtracking control verbs that
- are returned from calls to pcre2_match() to be displayed. If a mark is
- returned for a match, non-match, or partial match, pcre2test shows it.
- For a match, it is on a line by itself, tagged with "MK:". Otherwise,
+ are returned from calls to pcre2_match() to be displayed. If a mark is
+ returned for a match, non-match, or partial match, pcre2test shows it.
+ For a match, it is on a line by itself, tagged with "MK:". Otherwise,
it is added to the non-match message.
Showing memory usage
- The memory modifier causes pcre2test to log all memory allocation and
+ The memory modifier causes pcre2test to log all memory allocation and
freeing calls that occur during a match operation.
Setting a starting offset
- The offset modifier sets an offset in the subject string at which
+ The offset modifier sets an offset in the subject string at which
matching starts. Its value is a number of code units, not characters.
Setting an offset limit
- The offset_limit modifier sets a limit for unanchored matches. If a
+ The offset_limit modifier sets a limit for unanchored matches. If a
match cannot be found starting at or before this offset in the subject,
a "no match" return is given. The data value is a number of code units,
- not characters. When this modifier is used, the use_offset_limit modi-
+ not characters. When this modifier is used, the use_offset_limit modi-
fier must have been set for the pattern; if not, an error is generated.
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
+ 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
available for storing matching information. The default is 15.
- A value of zero is useful when testing the POSIX API because it causes
+ A value of zero is useful when testing the POSIX API because it causes
regexec() to be called with a NULL capture vector. When not testing the
- POSIX API, a value of zero is used to cause pcre2_match_data_cre-
- ate_from_pattern() to be called, in order to create a match block of
+ POSIX API, a value of zero is used to cause pcre2_match_data_cre-
+ ate_from_pattern() to be called, in order to create a match block of
exactly the right size for the pattern. (It is not possible to create a
- match block with a zero-length ovector; there is always at least one
+ match block with a zero-length ovector; there is always at least one
pair of offsets.)
Passing the subject as zero-terminated
@@ -1085,56 +1129,56 @@
By default, the subject string is passed to a native API matching func-
tion with its correct length. In order to test the facility for passing
- a zero-terminated string, the zero_terminate modifier is provided. It
+ a zero-terminated string, the zero_terminate modifier is provided. It
causes the length to be passed as PCRE2_ZERO_TERMINATED. (When matching
- via the POSIX interface, this modifier has no effect, as there is no
+ via the POSIX interface, this modifier has no effect, as there is no
facility for passing a length.)
- When testing pcre2_substitute(), this modifier also has the effect of
+ When testing pcre2_substitute(), this modifier also has the effect of
passing the replacement string as zero-terminated.
Passing a NULL context
- Normally, pcre2test passes a context block to pcre2_match(),
+ Normally, pcre2test passes a context block to pcre2_match(),
pcre2_dfa_match() or pcre2_jit_match(). If the null_context modifier is
- set, however, NULL is passed. This is for testing that the matching
+ set, however, NULL is passed. This is for testing that the matching
functions behave correctly in this case (they use default values). This
- modifier cannot be used with the find_limits modifier or when testing
+ modifier cannot be used with the find_limits modifier or when testing
the substitution function.
THE ALTERNATIVE MATCHING FUNCTION
- By default, pcre2test uses the standard PCRE2 matching function,
+ By default, pcre2test uses the standard PCRE2 matching function,
pcre2_match() to match each subject line. PCRE2 also supports an alter-
- native matching function, pcre2_dfa_match(), which operates in a dif-
- ferent way, and has some restrictions. The differences between the two
+ native matching function, pcre2_dfa_match(), which operates in a dif-
+ ferent way, and has some restrictions. The differences between the two
functions are described in the pcre2matching documentation.
- If the dfa modifier is set, the alternative matching function is used.
- This function finds all possible matches at a given point in the sub-
- ject. If, however, the dfa_shortest modifier is set, processing stops
- after the first match is found. This is always the shortest possible
+ If the dfa modifier is set, the alternative matching function is used.
+ This function finds all possible matches at a given point in the sub-
+ ject. If, however, the dfa_shortest modifier is set, processing stops
+ after the first match is found. This is always the shortest possible
match.
DEFAULT OUTPUT FROM pcre2test
- This section describes the output when the normal matching function,
+ This section describes the output when the normal matching function,
pcre2_match(), is being used.
- 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
+ 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.)
For any other return, pcre2test outputs the PCRE2 negative error number
- and a short descriptive phrase. If the error is a failed UTF string
- check, the code unit offset of the start of the failing character is
+ and a short descriptive phrase. If the error is a failed UTF string
+ check, the code unit offset of the start of the failing character is
also output. Here is an example of an interactive pcre2test run.
$ pcre2test
@@ -1150,8 +1194,8 @@
Unset capturing substrings that are not followed by one that is set are
not shown by pcre2test unless the allcaptures modifier is specified. In
the following example, there are two capturing substrings, but when the
- first data line is matched, the second, unset substring is not shown.
- An "internal" unset substring is shown as "<unset>", as for the second
+ first data line is matched, the second, unset substring is not shown.
+ An "internal" unset substring is shown as "<unset>", as for the second
data line.
re> /(a)|(b)/
@@ -1163,11 +1207,11 @@
1: <unset>
2: b
- If the strings contain any non-printing characters, they are output as
- \xhh escapes if the value is less than 256 and UTF mode is not set.
+ If the strings contain any non-printing characters, they are output as
+ \xhh escapes if the value is less than 256 and UTF mode is not set.
Otherwise they are output as \x{hh...} escapes. See below for the defi-
- nition of non-printing characters. If the /aftertext modifier is set,
- the output for substring 0 is followed by the the rest of the subject
+ nition of non-printing characters. If the /aftertext modifier is set,
+ the output for substring 0 is followed by the the rest of the subject
string, identified by "0+" like this:
re> /cat/aftertext
@@ -1175,7 +1219,7 @@
0: cat
0+ aract
- If global matching is requested, the results of successive matching
+ If global matching is requested, the results of successive matching
attempts are output in sequence, like this:
re> /\Bi(\w\w)/g
@@ -1187,8 +1231,8 @@
0: ipp
1: pp
- "No match" is output only if the first match attempt fails. Here is an
- example of a failure message (the offset 4 that is specified by the
+ "No match" is output only if the first match attempt fails. Here is an
+ example of a failure message (the offset 4 that is specified by the
offset modifier is past the end of the subject string):
re> /xyz/
@@ -1196,7 +1240,7 @@
Error -24 (bad offset value)
Note that whereas patterns can be continued over several lines (a plain
- ">" prompt is used for continuations), subject lines may not. However
+ ">" prompt is used for continuations), subject lines may not. However
newlines can be included in a subject by means of the \n escape (or \r,
\r\n, etc., depending on the newline sequence setting).
@@ -1204,7 +1248,7 @@
OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
When the alternative matching function, pcre2_dfa_match(), is used, the
- output consists of a list of all the matches that start at the first
+ output consists of a list of all the matches that start at the first
point in the subject where there is at least one match. For example:
re> /(tang|tangerine|tan)/
@@ -1213,11 +1257,11 @@
1: tang
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
+ 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.)
@@ -1233,16 +1277,16 @@
1: tan
0: tan
- The alternative matching function does not support substring capture,
- so the modifiers that are concerned with captured substrings are not
+ The alternative matching function does not support substring capture,
+ so the modifiers that are concerned with captured substrings are not
relevant.
RESTARTING AFTER A PARTIAL MATCH
- When the alternative matching function has given the PCRE2_ERROR_PAR-
+ When the alternative matching function has given the PCRE2_ERROR_PAR-
TIAL return, indicating that the subject partially matched the pattern,
- you can restart the match with additional subject data by means of the
+ you can restart the match with additional subject data by means of the
dfa_restart modifier. For example:
re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
@@ -1251,7 +1295,7 @@
data> n05\=dfa,dfa_restart
0: n05
- For further information about partial matching, see the pcre2partial
+ For further information about partial matching, see the pcre2partial
documentation.
@@ -1258,37 +1302,37 @@
CALLOUTS
If the pattern contains any callout requests, pcre2test's callout func-
- tion is called during matching unless callout_none is specified. This
+ tion is called during matching unless callout_none is specified. This
works with both matching functions.
- The callout function in pcre2test returns zero (carry on matching) by
- default, but you can use a callout_fail modifier in a subject line (as
+ The callout function in pcre2test returns zero (carry on matching) by
+ default, but you can use a callout_fail modifier in a subject line (as
described above) to change this and other parameters of the callout.
Inserting callouts can be helpful when using pcre2test to check compli-
- cated regular expressions. For further information about callouts, see
+ cated regular expressions. For further information about callouts, see
the pcre2callout documentation.
- The output for callouts with numerical arguments and those with string
+ The output for callouts with numerical arguments and those with string
arguments is slightly different.
Callouts with numerical arguments
By default, the callout function displays the callout number, the start
- and current positions in the subject text at the callout time, and the
+ and current positions in the subject text at the callout time, and the
next pattern item to be tested. For example:
--->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
+ 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.
Callouts numbered 255 are assumed to be automatic callouts, inserted as
- a result of the /auto_callout pattern modifier. In this case, instead
+ a result of the /auto_callout pattern modifier. In this case, instead
of showing the callout number, the offset in the pattern, preceded by a
plus, is output. For example:
@@ -1302,7 +1346,7 @@
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
+ ever a change of latest mark is passed to the callout function. For
example:
re> /a(*MARK:X)bc/auto_callout
@@ -1316,17 +1360,17 @@
+12 ^ ^
0: abc
- The mark changes between matching "a" and "b", but stays the same for
- the rest of the match, so nothing more is output. If, as a result of
- backtracking, the mark reverts to being unset, the text "<unset>" is
+ The mark changes between matching "a" and "b", but stays the same for
+ the rest of the match, so nothing more is output. If, as a result of
+ backtracking, the mark reverts to being unset, the text "<unset>" is
output.
Callouts with string arguments
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
+ 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
reflected for each callout. For example:
re> /^ab(?C'first')cd(?C"second")ef/
@@ -1343,39 +1387,39 @@
NON-PRINTING CHARACTERS
When pcre2test is outputting text in the compiled version of a pattern,
- bytes other than 32-126 are always treated as non-printing characters
+ bytes other than 32-126 are always treated as non-printing characters
and are therefore shown as hex escapes.
- 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
+ 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.
SAVING AND RESTORING COMPILED PATTERNS
- It is possible to save compiled patterns on disc or elsewhere, and
+ It is possible to save compiled patterns on disc or elsewhere, and
reload them later, subject to a number of restrictions. JIT data cannot
- be saved. The host on which the patterns are reloaded must be running
+ be saved. 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 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
+ 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
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-
+ 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.
- When a pattern with push modifier is successfully compiled, 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
+ When a pattern with push modifier is successfully compiled, 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 this means, a number of patterns can be compiled and retained.
- The push modifier is incompatible with posix, and control modifiers
+ The push modifier is incompatible with posix, and control modifiers
that act at match time are ignored (with a message). The jitverify mod-
ifier applies only at compile time. The command
@@ -1382,20 +1426,20 @@
#save <filename>
causes all the stacked patterns to be serialized and the result written
- to the named file. Afterwards, all the stacked patterns are freed. The
+ to the named file. Afterwards, all the stacked patterns are freed. The
command
#load <filename>
- reads the data in the file, and then arranges for it to be de-serial-
- ized, with the resulting compiled patterns added to the pattern stack.
- The pattern on the top of the stack can be retrieved by the #pop com-
- mand, which must be followed by lines of subjects that are to be
- 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, and push are not allowed, nor are any option-
- setting modifiers. The JIT modifiers are, however permitted. Here is
+ reads the data in the file, and then arranges for it to be de-serial-
+ ized, with the resulting compiled patterns added to the pattern stack.
+ The pattern on the top of the stack can be retrieved by the #pop com-
+ mand, which must be followed by lines of subjects that are to be
+ 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, and push are not allowed, nor are any option-
+ setting modifiers. The JIT modifiers are, however permitted. Here is
an example that saves and reloads two patterns.
/abc/push
@@ -1408,7 +1452,7 @@
#pop jit,bincode
abc
- If jitverify is used with #pop, it does not automatically imply jit,
+ If jitverify is used with #pop, it does not automatically imply jit,
which is different behaviour from when it is used on a pattern.
@@ -1427,5 +1471,5 @@
REVISION
- Last updated: 17 October 2015
+ Last updated: 05 November 2015
Copyright (c) 1997-2015 University of Cambridge.
Modified: code/trunk/src/pcre2.h
===================================================================
--- code/trunk/src/pcre2.h 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/src/pcre2.h 2015-11-05 17:33:39 UTC (rev 414)
@@ -396,6 +396,8 @@
PCRE2_EXP_DECL int pcre2_set_bsr(pcre2_compile_context *, uint32_t); \
PCRE2_EXP_DECL int pcre2_set_character_tables(pcre2_compile_context *, \
const unsigned char *); \
+PCRE2_EXP_DECL int pcre2_set_max_pattern_length(pcre2_compile_context *, \
+ PCRE2_SIZE); \
PCRE2_EXP_DECL int pcre2_set_newline(pcre2_compile_context *, uint32_t); \
PCRE2_EXP_DECL int pcre2_set_parens_nest_limit(pcre2_compile_context *, \
uint32_t); \
@@ -616,6 +618,7 @@
#define pcre2_set_character_tables PCRE2_SUFFIX(pcre2_set_character_tables_)
#define pcre2_set_compile_recursion_guard PCRE2_SUFFIX(pcre2_set_compile_recursion_guard_)
#define pcre2_set_match_limit PCRE2_SUFFIX(pcre2_set_match_limit_)
+#define pcre2_set_max_pattern_length PCRE2_SUFFIX(pcre2_set_max_pattern_length_)
#define pcre2_set_newline PCRE2_SUFFIX(pcre2_set_newline_)
#define pcre2_set_parens_nest_limit PCRE2_SUFFIX(pcre2_set_parens_nest_limit_)
#define pcre2_set_offset_limit PCRE2_SUFFIX(pcre2_set_offset_limit_)
Modified: code/trunk/src/pcre2.h.in
===================================================================
--- code/trunk/src/pcre2.h.in 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/src/pcre2.h.in 2015-11-05 17:33:39 UTC (rev 414)
@@ -396,6 +396,8 @@
PCRE2_EXP_DECL int pcre2_set_bsr(pcre2_compile_context *, uint32_t); \
PCRE2_EXP_DECL int pcre2_set_character_tables(pcre2_compile_context *, \
const unsigned char *); \
+PCRE2_EXP_DECL int pcre2_set_max_pattern_length(pcre2_compile_context *, \
+ PCRE2_SIZE); \
PCRE2_EXP_DECL int pcre2_set_newline(pcre2_compile_context *, uint32_t); \
PCRE2_EXP_DECL int pcre2_set_parens_nest_limit(pcre2_compile_context *, \
uint32_t); \
@@ -616,6 +618,7 @@
#define pcre2_set_character_tables PCRE2_SUFFIX(pcre2_set_character_tables_)
#define pcre2_set_compile_recursion_guard PCRE2_SUFFIX(pcre2_set_compile_recursion_guard_)
#define pcre2_set_match_limit PCRE2_SUFFIX(pcre2_set_match_limit_)
+#define pcre2_set_max_pattern_length PCRE2_SUFFIX(pcre2_set_max_pattern_length_)
#define pcre2_set_newline PCRE2_SUFFIX(pcre2_set_newline_)
#define pcre2_set_parens_nest_limit PCRE2_SUFFIX(pcre2_set_parens_nest_limit_)
#define pcre2_set_offset_limit PCRE2_SUFFIX(pcre2_set_offset_limit_)
Modified: code/trunk/src/pcre2_compile.c
===================================================================
--- code/trunk/src/pcre2_compile.c 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/src/pcre2_compile.c 2015-11-05 17:33:39 UTC (rev 414)
@@ -583,7 +583,7 @@
ERR51, ERR52, ERR53, ERR54, ERR55, ERR56, ERR57, ERR58, ERR59, ERR60,
ERR61, ERR62, ERR63, ERR64, ERR65, ERR66, ERR67, ERR68, ERR69, ERR70,
ERR71, ERR72, ERR73, ERR74, ERR75, ERR76, ERR77, ERR78, ERR79, ERR80,
- ERR81, ERR82, ERR83, ERR84, ERR85, ERR86, ERR87 };
+ ERR81, ERR82, ERR83, ERR84, ERR85, ERR86, ERR87, ERR88 };
/* Error codes that correspond to negative error codes returned by
find_fixedlength(). */
@@ -2988,7 +2988,7 @@
if ((unsigned int)arglen > MAX_MARK)
{
*errorcodeptr = ERR76;
- *ptrptr = ptr;
+ *ptrptr = ptr;
return -1;
}
}
@@ -8128,10 +8128,24 @@
/* A zero-terminated pattern is indicated by the special length value
PCRE2_ZERO_TERMINATED. Otherwise, we make a copy of the pattern and add a zero,
to ensure that it is always possible to look one code unit beyond the end of
-the pattern's characters. */
+the pattern's characters. In both cases, check that the pattern is overlong. */
-if (patlen == PCRE2_ZERO_TERMINATED) patlen = PRIV(strlen)(pattern); else
+if (patlen == PCRE2_ZERO_TERMINATED)
{
+ patlen = PRIV(strlen)(pattern);
+ if (patlen > ccontext->max_pattern_length)
+ {
+ *errorptr = ERR88;
+ return NULL;
+ }
+ }
+else
+ {
+ if (patlen > ccontext->max_pattern_length)
+ {
+ *errorptr = ERR88;
+ return NULL;
+ }
if (patlen < COPIED_PATTERN_SIZE)
copied_pattern = stack_copied_pattern;
else
Modified: code/trunk/src/pcre2_context.c
===================================================================
--- code/trunk/src/pcre2_context.c 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/src/pcre2_context.c 2015-11-05 17:33:39 UTC (rev 414)
@@ -131,13 +131,14 @@
when no context is supplied to the compile function. */
const pcre2_compile_context PRIV(default_compile_context) = {
- { default_malloc, default_free, NULL },
- NULL,
- NULL,
- PRIV(default_tables),
- BSR_DEFAULT,
- NEWLINE_DEFAULT,
- PARENS_NEST_LIMIT };
+ { default_malloc, default_free, NULL }, /* Default memory handling */
+ NULL, /* Stack guard */
+ NULL, /* Stack guard data */
+ PRIV(default_tables), /* Character tables */
+ PCRE2_UNSET, /* Max pattern length */
+ BSR_DEFAULT, /* Backslash R default */
+ NEWLINE_DEFAULT, /* Newline convention */
+ PARENS_NEST_LIMIT }; /* As it says */
/* The create function copies the default into the new memory, but must
override the default memory handling functions if a gcontext was provided. */
@@ -169,7 +170,7 @@
#endif
NULL,
NULL,
- PCRE2_UNSET, /* Offset limit */
+ PCRE2_UNSET, /* Offset limit */
MATCH_LIMIT,
MATCH_LIMIT_RECURSION };
@@ -296,6 +297,13 @@
}
PCRE2_EXP_DEFN int PCRE2_CALL_CONVENTION
+pcre2_set_max_pattern_length(pcre2_compile_context *ccontext, PCRE2_SIZE length)
+{
+ccontext->max_pattern_length = length;
+return 0;
+}
+
+PCRE2_EXP_DEFN int PCRE2_CALL_CONVENTION
pcre2_set_newline(pcre2_compile_context *ccontext, uint32_t newline)
{
switch(newline)
Modified: code/trunk/src/pcre2_error.c
===================================================================
--- code/trunk/src/pcre2_error.c 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/src/pcre2_error.c 2015-11-05 17:33:39 UTC (rev 414)
@@ -172,6 +172,7 @@
"using \\C is disabled in this PCRE2 library\0"
"regular expression is too complicated\0"
"lookbehind assertion is too long\0"
+ "pattern string is longer than the limit set by the application\0"
;
/* Match-time and UTF error texts are in the same format. */
Modified: code/trunk/src/pcre2_intmodedep.h
===================================================================
--- code/trunk/src/pcre2_intmodedep.h 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/src/pcre2_intmodedep.h 2015-11-05 17:33:39 UTC (rev 414)
@@ -562,6 +562,7 @@
int (*stack_guard)(uint32_t, void *);
void *stack_guard_data;
const uint8_t *tables;
+ PCRE2_SIZE max_pattern_length;
uint16_t bsr_convention;
uint16_t newline_convention;
uint32_t parens_nest_limit;
Modified: code/trunk/src/pcre2test.c
===================================================================
--- code/trunk/src/pcre2test.c 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/src/pcre2test.c 2015-11-05 17:33:39 UTC (rev 414)
@@ -540,6 +540,7 @@
{ "mark", MOD_PNDP, MOD_CTL, CTL_MARK, PO(control) },
{ "match_limit", MOD_CTM, MOD_INT, 0, MO(match_limit) },
{ "match_unset_backref", MOD_PAT, MOD_OPT, PCRE2_MATCH_UNSET_BACKREF, PO(options) },
+ { "max_pattern_length", MOD_CTC, MOD_SIZ, 0, CO(max_pattern_length) },
{ "memory", MOD_PD, MOD_CTL, CTL_MEMORY, PD(control) },
{ "multiline", MOD_PATP, MOD_OPT, PCRE2_MULTILINE, PO(options) },
{ "never_backslash_c", MOD_PAT, MOD_OPT, PCRE2_NEVER_BACKSLASH_C, PO(options) },
@@ -1094,6 +1095,14 @@
else \
pcre2_set_match_limit_32(G(a,32),b)
+#define PCRE2_SET_MAX_PATTERN_LENGTH(a,b) \
+ if (test_mode == PCRE8_MODE) \
+ pcre2_set_max_pattern_length_8(G(a,8),b); \
+ else if (test_mode == PCRE16_MODE) \
+ pcre2_set_max_pattern_length_16(G(a,16),b); \
+ else \
+ pcre2_set_max_pattern_length_32(G(a,32),b)
+
#define PCRE2_SET_OFFSET_LIMIT(a,b) \
if (test_mode == PCRE8_MODE) \
pcre2_set_offset_limit_8(G(a,8),b); \
@@ -1502,6 +1511,12 @@
else \
G(pcre2_set_match_limit_,BITTWO)(G(a,BITTWO),b)
+#define PCRE2_SET_MAX_PATTERN_LENGTH(a,b) \
+ if (test_mode == G(G(PCRE,BITONE),_MODE)) \
+ G(pcre2_set_max_pattern_length_,BITONE)(G(a,BITONE),b); \
+ else \
+ G(pcre2_set_max_pattern_length_,BITTWO)(G(a,BITTWO),b)
+
#define PCRE2_SET_OFFSET_LIMIT(a,b) \
if (test_mode == G(G(PCRE,BITONE),_MODE)) \
G(pcre2_set_offset_limit_,BITONE)(G(a,BITONE),b); \
@@ -1706,6 +1721,7 @@
#define PCRE2_SET_COMPILE_RECURSION_GUARD(a,b,c) \
pcre2_set_compile_recursion_guard_8(G(a,8),b,c)
#define PCRE2_SET_MATCH_LIMIT(a,b) pcre2_set_match_limit_8(G(a,8),b)
+#define PCRE2_SET_MAX_PATTERN_LENGTH(a,b) pcre2_set_max_pattern_length_8(G(a,8),b)
#define PCRE2_SET_OFFSET_LIMIT(a,b) pcre2_set_offset_limit_8(G(a,8),b)
#define PCRE2_SET_PARENS_NEST_LIMIT(a,b) pcre2_set_parens_nest_limit_8(G(a,8),b)
#define PCRE2_SET_RECURSION_LIMIT(a,b) pcre2_set_recursion_limit_8(G(a,8),b)
@@ -1798,6 +1814,7 @@
#define PCRE2_SET_COMPILE_RECURSION_GUARD(a,b,c) \
pcre2_set_compile_recursion_guard_16(G(a,16),b,c)
#define PCRE2_SET_MATCH_LIMIT(a,b) pcre2_set_match_limit_16(G(a,16),b)
+#define PCRE2_SET_MAX_PATTERN_LENGTH(a,b) pcre2_set_max_pattern_length_16(G(a,16),b)
#define PCRE2_SET_OFFSET_LIMIT(a,b) pcre2_set_offset_limit_16(G(a,16),b)
#define PCRE2_SET_PARENS_NEST_LIMIT(a,b) pcre2_set_parens_nest_limit_16(G(a,16),b)
#define PCRE2_SET_RECURSION_LIMIT(a,b) pcre2_set_recursion_limit_16(G(a,16),b)
@@ -1890,6 +1907,7 @@
#define PCRE2_SET_COMPILE_RECURSION_GUARD(a,b,c) \
pcre2_set_compile_recursion_guard_32(G(a,32),b,c)
#define PCRE2_SET_MATCH_LIMIT(a,b) pcre2_set_match_limit_32(G(a,32),b)
+#define PCRE2_SET_MAX_PATTERN_LENGTH(a,b) pcre2_set_max_pattern_length_32(G(a,32),b)
#define PCRE2_SET_OFFSET_LIMIT(a,b) pcre2_set_offset_limit_32(G(a,32),b)
#define PCRE2_SET_PARENS_NEST_LIMIT(a,b) pcre2_set_parens_nest_limit_32(G(a,32),b)
#define PCRE2_SET_RECURSION_LIMIT(a,b) pcre2_set_recursion_limit_32(G(a,32),b)
Modified: code/trunk/testdata/testinput2
===================================================================
--- code/trunk/testdata/testinput2 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/testdata/testinput2 2015-11-05 17:33:39 UTC (rev 414)
@@ -4603,4 +4603,14 @@
/(?'abcdefghijklmnopqrstuvwxyzABCDEF'justright)/
+# These two use zero-termination
+/abcd/max_pattern_length=3
+
+/abc/max_pattern_length=3
+
+# These two, being hex, pass the length
+/abcdefab/hex,max_pattern_length=3
+
+/abcdef/hex,max_pattern_length=3
+
# End of testinput2
Modified: code/trunk/testdata/testoutput2
===================================================================
--- code/trunk/testdata/testoutput2 2015-11-03 20:09:33 UTC (rev 413)
+++ code/trunk/testdata/testoutput2 2015-11-05 17:33:39 UTC (rev 414)
@@ -14699,4 +14699,16 @@
/(?'abcdefghijklmnopqrstuvwxyzABCDEF'justright)/
+# These two use zero-termination
+/abcd/max_pattern_length=3
+Failed: error 188 at offset 0: pattern string is longer than the limit set by the application
+
+/abc/max_pattern_length=3
+
+# These two, being hex, pass the length
+/abcdefab/hex,max_pattern_length=3
+Failed: error 188 at offset 0: pattern string is longer than the limit set by the application
+
+/abcdef/hex,max_pattern_length=3
+
# End of testinput2
