Revision: 1308
http://www.exim.org/viewvc/pcre2?view=rev&revision=1308
Author: ph10
Date: 2021-04-28 16:37:48 +0100 (Wed, 28 Apr 2021)
Log Message:
-----------
Documentation update
Modified Paths:
--------------
code/trunk/NON-AUTOTOOLS-BUILD
code/trunk/doc/html/NON-AUTOTOOLS-BUILD.txt
code/trunk/doc/html/pcre2.html
code/trunk/doc/html/pcre2test.html
code/trunk/doc/pcre2.txt
code/trunk/doc/pcre2test.txt
Modified: code/trunk/NON-AUTOTOOLS-BUILD
===================================================================
--- code/trunk/NON-AUTOTOOLS-BUILD 2021-04-28 14:21:38 UTC (rev 1307)
+++ code/trunk/NON-AUTOTOOLS-BUILD 2021-04-28 15:37:48 UTC (rev 1308)
@@ -40,7 +40,11 @@
The following are generic instructions for building the PCRE2 C library "by
hand". If you are going to use CMake, this section does not apply to you; you
-can skip ahead to the CMake section.
+can skip ahead to the CMake section. Note that the settings concerned with
+8-bit, 16-bit, and 32-bit code units relate to the type of data string that
+PCRE2 processes. They are NOT referring to the underlying operating system bit
+width. You do not have to do anything special to compile in a 64-bit
+environment, for example.
(1) Copy or rename the file src/config.h.generic as src/config.h, and edit the
macro settings that it contains to whatever is appropriate for your
@@ -86,11 +90,11 @@
The tables in src/pcre2_chartables.c are defaults. The caller of PCRE2 can
specify alternative tables at run time.
- (4) For an 8-bit library, compile the following source files from the src
- directory, setting -DPCRE2_CODE_UNIT_WIDTH=8 as a compiler option. Also
- set -DHAVE_CONFIG_H if you have set up src/config.h with your
- configuration, or else use other -D settings to change the configuration
- as required.
+ (4) For a library that supports 8-bit code units in the character strings that
+ it processes, compile the following source files from the src directory,
+ setting -DPCRE2_CODE_UNIT_WIDTH=8 as a compiler option. Also set
+ -DHAVE_CONFIG_H if you have set up src/config.h with your configuration,
+ or else use other -D settings to change the configuration as required.
pcre2_auto_possess.c
pcre2_chartables.c
@@ -142,9 +146,9 @@
If your system has static and shared libraries, you may have to do this
once for each type.
- (6) If you want to build a 16-bit library or 32-bit library (as well as, or
- instead of the 8-bit library) just supply 16 or 32 as the value of
- -DPCRE2_CODE_UNIT_WIDTH when you are compiling.
+ (6) If you want to build a library that supports 16-bit or 32-bit code units,
+ (as well as, or instead of the 8-bit library) just supply 16 or 32 as the
+ value of -DPCRE2_CODE_UNIT_WIDTH when you are compiling.
(7) If you want to build the POSIX wrapper functions (which apply only to the
8-bit library), ensure that you have the src/pcre2posix.h file and then
@@ -401,6 +405,6 @@
z/OS file formats. The port provides an API for LE languages such as COBOL and
for the z/OS and z/VM versions of the Rexx languages.
-==============================
-Last Updated: 14 November 2018
-==============================
+===========================
+Last Updated: 28 April 2021
+===========================
Modified: code/trunk/doc/html/NON-AUTOTOOLS-BUILD.txt
===================================================================
--- code/trunk/doc/html/NON-AUTOTOOLS-BUILD.txt 2021-04-28 14:21:38 UTC (rev 1307)
+++ code/trunk/doc/html/NON-AUTOTOOLS-BUILD.txt 2021-04-28 15:37:48 UTC (rev 1308)
@@ -40,7 +40,11 @@
The following are generic instructions for building the PCRE2 C library "by
hand". If you are going to use CMake, this section does not apply to you; you
-can skip ahead to the CMake section.
+can skip ahead to the CMake section. Note that the settings concerned with
+8-bit, 16-bit, and 32-bit code units relate to the type of data string that
+PCRE2 processes. They are NOT referring to the underlying operating system bit
+width. You do not have to do anything special to compile in a 64-bit
+environment, for example.
(1) Copy or rename the file src/config.h.generic as src/config.h, and edit the
macro settings that it contains to whatever is appropriate for your
@@ -86,11 +90,11 @@
The tables in src/pcre2_chartables.c are defaults. The caller of PCRE2 can
specify alternative tables at run time.
- (4) For an 8-bit library, compile the following source files from the src
- directory, setting -DPCRE2_CODE_UNIT_WIDTH=8 as a compiler option. Also
- set -DHAVE_CONFIG_H if you have set up src/config.h with your
- configuration, or else use other -D settings to change the configuration
- as required.
+ (4) For a library that supports 8-bit code units in the character strings that
+ it processes, compile the following source files from the src directory,
+ setting -DPCRE2_CODE_UNIT_WIDTH=8 as a compiler option. Also set
+ -DHAVE_CONFIG_H if you have set up src/config.h with your configuration,
+ or else use other -D settings to change the configuration as required.
pcre2_auto_possess.c
pcre2_chartables.c
@@ -142,9 +146,9 @@
If your system has static and shared libraries, you may have to do this
once for each type.
- (6) If you want to build a 16-bit library or 32-bit library (as well as, or
- instead of the 8-bit library) just supply 16 or 32 as the value of
- -DPCRE2_CODE_UNIT_WIDTH when you are compiling.
+ (6) If you want to build a library that supports 16-bit or 32-bit code units,
+ (as well as, or instead of the 8-bit library) just supply 16 or 32 as the
+ value of -DPCRE2_CODE_UNIT_WIDTH when you are compiling.
(7) If you want to build the POSIX wrapper functions (which apply only to the
8-bit library), ensure that you have the src/pcre2posix.h file and then
@@ -401,6 +405,6 @@
z/OS file formats. The port provides an API for LE languages such as COBOL and
for the z/OS and z/VM versions of the Rexx languages.
-==============================
-Last Updated: 14 November 2018
-==============================
+===========================
+Last Updated: 28 April 2021
+===========================
Modified: code/trunk/doc/html/pcre2.html
===================================================================
--- code/trunk/doc/html/pcre2.html 2021-04-28 14:21:38 UTC (rev 1307)
+++ code/trunk/doc/html/pcre2.html 2021-04-28 15:37:48 UTC (rev 1308)
@@ -38,8 +38,14 @@
that give better ECMAScript (aka JavaScript) compatibility.
</P>
<P>
-The source code for PCRE2 can be compiled to support 8-bit, 16-bit, or 32-bit
-code units, which means that up to three separate libraries may be installed.
+The source code for PCRE2 can be compiled to support strings of 8-bit, 16-bit,
+or 32-bit code units, which means that up to three separate libraries may be
+installed, one for each code unit size. The size of code unit is not related to
+the bit size of the underlying hardware. In a 64-bit environment that also
+supports 32-bit applications, versions of PCRE2 that are compiled in both
+64-bit and 32-bit modes may be needed.
+</P>
+<P>
The original work to extend PCRE to 16-bit and 32-bit code units was done by
Zoltan Herczeg and Christian Persch, respectively. In all three cases, strings
can be interpreted either as one character per code unit, or as UTF-encoded
@@ -198,9 +204,9 @@
</P>
<br><a name="SEC5" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 17 September 2018
+Last updated: 28 April 2021
<br>
-Copyright © 1997-2018 University of Cambridge.
+Copyright © 1997-2021 University of Cambridge.
<br>
<p>
Return to the <a href="index.html">PCRE2 index page</a>.
Modified: code/trunk/doc/html/pcre2test.html
===================================================================
--- code/trunk/doc/html/pcre2test.html 2021-04-28 14:21:38 UTC (rev 1307)
+++ code/trunk/doc/html/pcre2test.html 2021-04-28 15:37:48 UTC (rev 1308)
@@ -1213,7 +1213,7 @@
The following modifiers affect the matching process or request additional
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.
+pattern, but can be overridden by modifiers on the subject.
<pre>
aftertext show text after match
allaftertext show text after captures
@@ -1421,6 +1421,11 @@
a modifier. This is not thought to be an issue in a test program.
</P>
<P>
+Specifying a completely empty replacement string disables this modifier.
+However, it is possible to specify an empty replacement by providing a buffer
+length, as described below, for an otherwise empty replacement.
+</P>
+<P>
Unlike subject strings, <b>pcre2test</b> 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
@@ -2119,9 +2124,9 @@
</P>
<br><a name="SEC21" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 14 September 2020
+Last updated: 28 April 2021
<br>
-Copyright © 1997-2020 University of Cambridge.
+Copyright © 1997-2021 University of Cambridge.
<br>
<p>
Return to the <a href="index.html">PCRE2 index page</a>.
Modified: code/trunk/doc/pcre2.txt
===================================================================
--- code/trunk/doc/pcre2.txt 2021-04-28 14:21:38 UTC (rev 1307)
+++ code/trunk/doc/pcre2.txt 2021-04-28 15:37:48 UTC (rev 1308)
@@ -34,93 +34,98 @@
requesting some minor changes that give better ECMAScript (aka Java-
Script) compatibility.
- The source code for PCRE2 can be compiled to support 8-bit, 16-bit, or
- 32-bit code units, which means that up to three separate libraries may
- be installed. The original work to extend PCRE to 16-bit and 32-bit
- code units was done by Zoltan Herczeg and Christian Persch, respec-
- tively. In all three cases, strings can be interpreted either as one
- character per code unit, or as UTF-encoded Unicode, with support for
- Unicode general category properties. Unicode support is optional at
- build time (but is the default). However, processing strings as UTF
- code units must be enabled explicitly at run time. The version of Uni-
- code in use can be discovered by running
+ The source code for PCRE2 can be compiled to support strings of 8-bit,
+ 16-bit, or 32-bit code units, which means that up to three separate li-
+ braries may be installed, one for each code unit size. The size of code
+ unit is not related to the bit size of the underlying hardware. In a
+ 64-bit environment that also supports 32-bit applications, versions of
+ PCRE2 that are compiled in both 64-bit and 32-bit modes may be needed.
+ The original work to extend PCRE to 16-bit and 32-bit code units was
+ done by Zoltan Herczeg and Christian Persch, respectively. In all three
+ cases, strings can be interpreted either as one character per code
+ unit, or as UTF-encoded Unicode, with support for Unicode general cate-
+ gory properties. Unicode support is optional at build time (but is the
+ default). However, processing strings as UTF code units must be enabled
+ explicitly at run time. The version of Unicode in use can be discovered
+ by running
+
pcre2test -C
- The three libraries contain identical sets of functions, with names
- ending in _8, _16, or _32, respectively (for example, pcre2_com-
- pile_8()). However, by defining PCRE2_CODE_UNIT_WIDTH to be 8, 16, or
- 32, a program that uses just one code unit width can be written using
+ The three libraries contain identical sets of functions, with names
+ ending in _8, _16, or _32, respectively (for example, pcre2_com-
+ pile_8()). However, by defining PCRE2_CODE_UNIT_WIDTH to be 8, 16, or
+ 32, a program that uses just one code unit width can be written using
generic names such as pcre2_compile(), and the documentation is written
assuming that this is the case.
In addition to the Perl-compatible matching function, PCRE2 contains an
- alternative function that matches the same compiled patterns in a dif-
+ alternative function that matches the same compiled patterns in a dif-
ferent way. In certain circumstances, the alternative function has some
- advantages. For a discussion of the two matching algorithms, see the
+ advantages. For a discussion of the two matching algorithms, see the
pcre2matching page.
- Details of exactly which Perl regular expression features are and are
- not supported by PCRE2 are given in separate documents. See the
- pcre2pattern and pcre2compat pages. There is a syntax summary in the
+ Details of exactly which Perl regular expression features are and are
+ not supported by PCRE2 are given in separate documents. See the
+ pcre2pattern and pcre2compat pages. There is a syntax summary in the
pcre2syntax page.
- Some features of PCRE2 can be included, excluded, or changed when the
- library is built. The pcre2_config() function makes it possible for a
- client to discover which features are available. The features them-
+ Some features of PCRE2 can be included, excluded, or changed when the
+ library is built. The pcre2_config() function makes it possible for a
+ client to discover which features are available. The features them-
selves are described in the pcre2build page. Documentation about build-
- ing PCRE2 for various operating systems can be found in the README and
+ ing PCRE2 for various operating systems can be found in the README and
NON-AUTOTOOLS_BUILD files in the source distribution.
- The libraries contains a number of undocumented internal functions and
- data tables that are used by more than one of the exported external
- functions, but which are not intended for use by external callers.
- Their names all begin with "_pcre2", which hopefully will not provoke
+ The libraries contains a number of undocumented internal functions and
+ data tables that are used by more than one of the exported external
+ functions, but which are not intended for use by external callers.
+ Their names all begin with "_pcre2", which hopefully will not provoke
any name clashes. In some environments, it is possible to control which
- external symbols are exported when a shared library is built, and in
+ external symbols are exported when a shared library is built, and in
these cases the undocumented symbols are not exported.
SECURITY CONSIDERATIONS
- If you are using PCRE2 in a non-UTF application that permits users to
- supply arbitrary patterns for compilation, you should be aware of a
+ If you are using PCRE2 in a non-UTF application that permits users to
+ supply arbitrary patterns for compilation, you should be aware of a
feature that allows users to turn on UTF support from within a pattern.
- For example, an 8-bit pattern that begins with "(*UTF)" turns on UTF-8
- mode, which interprets patterns and subjects as strings of UTF-8 code
+ For example, an 8-bit pattern that begins with "(*UTF)" turns on UTF-8
+ mode, which interprets patterns and subjects as strings of UTF-8 code
units instead of individual 8-bit characters. This causes both the pat-
- tern and any data against which it is matched to be checked for UTF-8
- validity. If the data string is very long, such a check might use suf-
- ficiently many resources as to cause your application to lose perfor-
+ tern and any data against which it is matched to be checked for UTF-8
+ validity. If the data string is very long, such a check might use suf-
+ ficiently many resources as to cause your application to lose perfor-
mance.
- One way of guarding against this possibility is to use the pcre2_pat-
- tern_info() function to check the compiled pattern's options for
- PCRE2_UTF. Alternatively, you can set the PCRE2_NEVER_UTF option when
- calling pcre2_compile(). This causes a compile time error if the pat-
+ One way of guarding against this possibility is to use the pcre2_pat-
+ tern_info() function to check the compiled pattern's options for
+ PCRE2_UTF. Alternatively, you can set the PCRE2_NEVER_UTF option when
+ calling pcre2_compile(). This causes a compile time error if the pat-
tern contains a UTF-setting sequence.
- The use of Unicode properties for character types such as \d can also
- be enabled from within the pattern, by specifying "(*UCP)". This fea-
+ The use of Unicode properties for character types such as \d can also
+ be enabled from within the pattern, by specifying "(*UCP)". This fea-
ture can be disallowed by setting the PCRE2_NEVER_UCP option.
- If your application is one that supports UTF, be aware that validity
- checking can take time. If the same data string is to be matched many
- times, you can use the PCRE2_NO_UTF_CHECK option for the second and
+ If your application is one that supports UTF, be aware that validity
+ checking can take time. If the same data string is to be matched many
+ times, you can use the PCRE2_NO_UTF_CHECK option for the second and
subsequent matches to avoid running redundant checks.
The use of the \C escape sequence in a UTF-8 or UTF-16 pattern can lead
- to problems, because it may leave the current matching point in the
- middle of a multi-code-unit character. The PCRE2_NEVER_BACKSLASH_C op-
+ to problems, because it may leave the current matching point in the
+ middle of a multi-code-unit character. The PCRE2_NEVER_BACKSLASH_C op-
tion can be used by an application to lock out the use of \C, causing a
- compile-time error if it is encountered. It is also possible to build
+ compile-time error if it is encountered. It is also possible to build
PCRE2 with the use of \C permanently disabled.
- Another way that performance can be hit is by running a pattern that
- has a very large search tree against a string that will never match.
- Nested unlimited repeats in a pattern are a common example. PCRE2 pro-
- vides some protection against this: see the pcre2_set_match_limit()
- function in the pcre2api page. There is a similar function called
+ Another way that performance can be hit is by running a pattern that
+ has a very large search tree against a string that will never match.
+ Nested unlimited repeats in a pattern are a common example. PCRE2 pro-
+ vides some protection against this: see the pcre2_set_match_limit()
+ function in the pcre2api page. There is a similar function called
pcre2_set_depth_limit() that can be used to restrict the amount of mem-
ory that is used.
@@ -127,14 +132,14 @@
USER DOCUMENTATION
- The user documentation for PCRE2 comprises a number of different sec-
- tions. In the "man" format, each of these is a separate "man page". In
- the HTML format, each is a separate page, linked from the index page.
- In the plain text format, the descriptions of the pcre2grep and
+ The user documentation for PCRE2 comprises a number of different sec-
+ tions. In the "man" format, each of these is a separate "man page". In
+ the HTML format, each is a separate page, linked from the index page.
+ In the plain text format, the descriptions of the pcre2grep and
pcre2test programs are in files called pcre2grep.txt and pcre2test.txt,
- respectively. The remaining sections, except for the pcre2demo section
- (which is a program listing), and the short pages for individual func-
- tions, are concatenated in pcre2.txt, for ease of searching. The sec-
+ respectively. The remaining sections, except for the pcre2demo section
+ (which is a program listing), and the short pages for individual func-
+ tions, are concatenated in pcre2.txt, for ease of searching. The sec-
tions are as follows:
pcre2 this document
@@ -160,7 +165,7 @@
pcre2test description of the pcre2test command
pcre2unicode discussion of Unicode and UTF support
- In the "man" and HTML formats, there is also a short page for each C
+ In the "man" and HTML formats, there is also a short page for each C
library function, listing its arguments and results.
@@ -170,15 +175,15 @@
University Computing Service
Cambridge, England.
- Putting an actual email address here is a spam magnet. If you want to
- email me, use my two initials, followed by the two digits 10, at the
+ Putting an actual email address here is a spam magnet. If you want to
+ email me, use my two initials, followed by the two digits 10, at the
domain cam.ac.uk.
REVISION
- Last updated: 17 September 2018
- Copyright (c) 1997-2018 University of Cambridge.
+ Last updated: 28 April 2021
+ Copyright (c) 1997-2021 University of Cambridge.
------------------------------------------------------------------------------
Modified: code/trunk/doc/pcre2test.txt
===================================================================
--- code/trunk/doc/pcre2test.txt 2021-04-28 14:21:38 UTC (rev 1307)
+++ code/trunk/doc/pcre2test.txt 2021-04-28 15:37:48 UTC (rev 1308)
@@ -1084,7 +1084,8 @@
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.
+ is matched against that pattern, but can be overridden by modifiers on
+ the subject.
aftertext show text after match
allaftertext show text after captures
@@ -1132,29 +1133,29 @@
zero_terminate pass the subject as zero-terminated
The effects of these modifiers are described in the following sections.
- When matching via the POSIX wrapper API, the aftertext, allaftertext,
- and ovector subject modifiers work as described below. All other modi-
+ When matching via the POSIX wrapper API, the aftertext, allaftertext,
+ and ovector subject modifiers work as described below. All other modi-
fiers are either ignored, with a warning message, or cause an error.
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,
- for both full and partial matches. 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 look-
- behind at the start of a match, or, for a complete match, a lookahead
+ The allusedtext modifier requests that all the text that was consulted
+ during a successful pattern match by the interpreter should be shown,
+ for both full and partial matches. 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 look-
+ behind at the start of a match, or, for a complete match, a lookahead
at the end, or if \K is used in the pattern. Characters that precede or
- follow the start and end of the actual match are indicated in the out-
+ follow the start and end of the actual match are indicated in the out-
put by '<' or '>' characters underneath them. Here is an example:
re> /(?<=pqr)abc(?=xyz)/
@@ -1165,16 +1166,16 @@
Partial match: pqrabcxy
<<<
- The first, complete match shows that the matched string is "abc", with
- the preceding and following strings "pqr" and "xyz" having been con-
- sulted during the match (when processing the assertions). The partial
+ The first, complete match shows that the matched string is "abc", with
+ the preceding and following strings "pqr" and "xyz" having been con-
+ sulted during the match (when processing the assertions). The partial
match can indicate only the preceding string.
- 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
+ is displayed from the starting character instead of from the match
point, with circumflex characters under the earlier characters. For ex-
ample:
@@ -1183,7 +1184,7 @@
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
@@ -1191,9 +1192,9 @@
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 match are output as "<unset>". This modifier is not relevant for
- DFA matching (which does no capturing) and does not apply when replace
+ the return code from pcre2_match()). Groups that did not take part in
+ the match are output as "<unset>". This modifier is not relevant for
+ DFA matching (which does no capturing) and does not apply when replace
is specified; it is ignored, with a warning message, if present.
Showing the entire ovector, for all outcomes
@@ -1200,53 +1201,53 @@
The allvector modifier requests that the entire ovector be shown, what-
ever the outcome of the match. Compare allcaptures, which shows only up
- to the maximum number of capture groups for the pattern, and then only
- for a successful complete non-DFA match. This modifier, which acts af-
- ter any match result, and also for DFA matching, provides a means of
- checking that there are no unexpected modifications to ovector fields.
- Before each match attempt, the ovector is filled with a special value,
- and if this is found in both elements of a capturing pair, "<un-
- changed>" is output. After a successful match, this applies to all
- groups after the maximum capture group for the pattern. In other cases
- it applies to the entire ovector. After a partial match, the first two
- elements are the only ones that should be set. After a DFA match, the
- amount of ovector that is used depends on the number of matches that
+ to the maximum number of capture groups for the pattern, and then only
+ for a successful complete non-DFA match. This modifier, which acts af-
+ ter any match result, and also for DFA matching, provides a means of
+ checking that there are no unexpected modifications to ovector fields.
+ Before each match attempt, the ovector is filled with a special value,
+ and if this is found in both elements of a capturing pair, "<un-
+ changed>" is output. After a successful match, this applies to all
+ groups after the maximum capture group for the pattern. In other cases
+ it applies to the entire ovector. After a partial match, the first two
+ elements are the only ones that should be set. After a DFA match, the
+ amount of ovector that is used depends on the number of matches that
were found.
Testing pattern callouts
- A callout function is supplied when pcre2test calls the library match-
- ing functions, unless callout_none is specified. Its behaviour can be
- controlled by various modifiers listed above whose names begin with
- callout_. Details are given in the section entitled "Callouts" below.
- Testing callouts from pcre2_substitute() is decribed separately in
+ A callout function is supplied when pcre2test calls the library match-
+ ing functions, unless callout_none is specified. Its behaviour can be
+ controlled by various modifiers listed above whose names begin with
+ callout_. Details are given in the section entitled "Callouts" below.
+ Testing callouts from pcre2_substitute() is decribed separately in
"Testing the substitution function" below.
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 re-
- tried. This imitates the way Perl handles such cases when using the /g
- modifier or the split() function. Normally, the start offset is ad-
- vanced by one character, but if the newline convention recognizes CRLF
- as a newline, and the current character is CR followed by LF, an ad-
+ match fails, the start offset is advanced, and the normal match is re-
+ tried. This imitates the way Perl handles such cases when using the /g
+ modifier or the split() function. Normally, the start offset is ad-
+ vanced by one character, but if the newline convention recognizes CRLF
+ as a newline, and the current character is CR followed by LF, an ad-
vance of two characters occurs.
Testing substring extraction functions
- 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 capture group name or num-
ber, for example:
@@ -1253,29 +1254,34 @@
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 (or after one call of
- pcre2_match() in the case of PCRE2_SUBSTITUTE_MATCHED). Note that re-
- placement strings cannot contain commas, because a comma signifies the
- end of a modifier. This is not thought to be an issue in a test pro-
+ If the replace modifier is set, the pcre2_substitute() function is
+ called instead of one of the matching functions (or after one call of
+ pcre2_match() in the case of PCRE2_SUBSTITUTE_MATCHED). Note that re-
+ placement strings cannot contain commas, because a comma signifies the
+ end of a modifier. This is not thought to be an issue in a test pro-
gram.
+ Specifying a completely empty replacement string disables this modi-
+ fier. However, it is possible to specify an empty replacement by pro-
+ viding a buffer length, as described below, for an otherwise empty re-
+ placement.
+
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
@@ -1929,5 +1935,5 @@
REVISION
- Last updated: 14 September 2020
- Copyright (c) 1997-2020 University of Cambridge.
+ Last updated: 28 April 2021
+ Copyright (c) 1997-2021 University of Cambridge.
