diff options
| author | ph10 <ph10@2f5784b3-3f2a-0410-8824-cb99058d5e15> | 2013-11-19 15:36:57 +0000 |
|---|---|---|
| committer | ph10 <ph10@2f5784b3-3f2a-0410-8824-cb99058d5e15> | 2013-11-19 15:36:57 +0000 |
| commit | 3d0a81dbf14c870df3ab19470bee0c29e1999521 (patch) | |
| tree | 511475cb8f16f29d723c3fed946eb744895e2fed /doc | |
| parent | 840d6a79dec6e3b5c1324207043fb93dea810223 (diff) | |
| download | pcre-3d0a81dbf14c870df3ab19470bee0c29e1999521.tar.gz | |
Source tidies for 8.34-RC1.
git-svn-id: svn://vcs.exim.org/pcre/code/trunk@1404 2f5784b3-3f2a-0410-8824-cb99058d5e15
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/html/NON-AUTOTOOLS-BUILD.txt | 4 | ||||
| -rw-r--r-- | doc/html/README.txt | 28 | ||||
| -rw-r--r-- | doc/html/index.html | 14 | ||||
| -rw-r--r-- | doc/html/pcre.html | 2 | ||||
| -rw-r--r-- | doc/html/pcre_compile.html | 3 | ||||
| -rw-r--r-- | doc/html/pcre_compile2.html | 3 | ||||
| -rw-r--r-- | doc/html/pcre_config.html | 1 | ||||
| -rw-r--r-- | doc/html/pcreapi.html | 189 | ||||
| -rw-r--r-- | doc/html/pcrecallout.html | 59 | ||||
| -rw-r--r-- | doc/html/pcrecompat.html | 16 | ||||
| -rw-r--r-- | doc/html/pcrelimits.html | 18 | ||||
| -rw-r--r-- | doc/html/pcrematching.html | 11 | ||||
| -rw-r--r-- | doc/html/pcrepartial.html | 12 | ||||
| -rw-r--r-- | doc/html/pcrepattern.html | 323 | ||||
| -rw-r--r-- | doc/html/pcreprecompile.html | 19 | ||||
| -rw-r--r-- | doc/html/pcresyntax.html | 26 | ||||
| -rw-r--r-- | doc/html/pcretest.html | 73 | ||||
| -rw-r--r-- | doc/pcre.txt | 2696 | ||||
| -rw-r--r-- | doc/pcre_compile.3 | 2 | ||||
| -rw-r--r-- | doc/pcre_compile2.3 | 2 | ||||
| -rw-r--r-- | doc/pcre_config.3 | 2 | ||||
| -rw-r--r-- | doc/pcreapi.3 | 18 | ||||
| -rw-r--r-- | doc/pcrecompat.3 | 6 | ||||
| -rw-r--r-- | doc/pcrepartial.3 | 6 | ||||
| -rw-r--r-- | doc/pcrepattern.3 | 38 | ||||
| -rw-r--r-- | doc/pcresyntax.3 | 10 | ||||
| -rw-r--r-- | doc/pcretest.1 | 20 | ||||
| -rw-r--r-- | doc/pcretest.txt | 406 |
28 files changed, 2263 insertions, 1744 deletions
diff --git a/doc/html/NON-AUTOTOOLS-BUILD.txt b/doc/html/NON-AUTOTOOLS-BUILD.txt index 74075f0..cddf3e0 100644 --- a/doc/html/NON-AUTOTOOLS-BUILD.txt +++ b/doc/html/NON-AUTOTOOLS-BUILD.txt @@ -171,8 +171,8 @@ can skip ahead to the CMake section. pcre16_version.c pcre16_xclass.c - (8) If you want to build a 16-bit library (as well as, or instead of the 8-bit - or 32-bit libraries) repeat steps 5-6 with the following files: + (8) If you want to build a 32-bit library (as well as, or instead of the 8-bit + or 16-bit libraries) repeat steps 5-6 with the following files: pcre32_byte_order.c pcre32_chartables.c diff --git a/doc/html/README.txt b/doc/html/README.txt index e14935e..51197df 100644 --- a/doc/html/README.txt +++ b/doc/html/README.txt @@ -9,8 +9,10 @@ from: ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.zip There is a mailing list for discussion about the development of PCRE at +pcre-dev@exim.org. You can access the archives and subscribe or manage your +subscription here: - pcre-dev@exim.org + https://lists.exim.org/mailman/listinfo/pcre-dev Please read the NEWS file if you are upgrading from a previous release. The contents of this README file are: @@ -112,6 +114,11 @@ contributions provided support for compiling PCRE on various flavours of Windows (I myself do not use Windows). Nowadays there is more Windows support in the standard distribution, so these contibutions have been archived. +A PCRE user maintains downloadable Windows binaries of the pcregrep and +pcretest programs here: + + http://www.rexegg.com/pcregrep-pcretest.html + Building PCRE on non-Unix-like systems -------------------------------------- @@ -262,9 +269,17 @@ library. They are also documented in the pcrebuild man page. on the "configure" command. -. PCRE has a counter that can be set to limit the amount of resources it uses. - If the limit is exceeded during a match, the match fails. The default is ten - million. You can change the default by setting, for example, +. PCRE has a counter that limits the depth of nesting of parentheses in a + pattern. This limits the amount of system stack that a pattern uses when it + is compiled. The default is 250, but you can change it by setting, for + example, + + --with-parens-nest-limit=500 + +. PCRE has a counter that can be set to limit the amount of resources it uses + when matching a pattern. If the limit is exceeded during a match, the match + fails. The default is ten million. You can change the default by setting, for + example, --with-match-limit=500000 @@ -344,7 +359,8 @@ library. They are also documented in the pcrebuild man page. report is generated by running "make coverage". If ccache is installed on your system, it must be disabled when building PCRE for coverage reporting. You can do this by setting the environment variable CCACHE_DISABLE=1 before - running "make" to build PCRE. + running "make" to build PCRE. There is more information about coverage + reporting in the "pcrebuild" documentation. . The pcregrep program currently supports only 8-bit data files, and so requires the 8-bit PCRE library. It is possible to compile pcregrep to use @@ -971,4 +987,4 @@ pcre_xxx, one with the name pcre16_xx, and a third with the name pcre32_xxx. Philip Hazel Email local part: ph10 Email domain: cam.ac.uk -Last updated: 28 April 2013 +Last updated: 05 November 2013 diff --git a/doc/html/index.html b/doc/html/index.html index 887f4d7..352c55d 100644 --- a/doc/html/index.html +++ b/doc/html/index.html @@ -1,10 +1,10 @@ <html> -<!-- This is a manually maintained file that is the root of the HTML version of - the PCRE documentation. When the HTML documents are built from the man - page versions, the entire doc/html directory is emptied, this file is then - copied into doc/html/index.html, and the remaining files therein are +<!-- This is a manually maintained file that is the root of the HTML version of + the PCRE documentation. When the HTML documents are built from the man + page versions, the entire doc/html directory is emptied, this file is then + copied into doc/html/index.html, and the remaining files therein are created by the 132html script. ---> +--> <head> <title>PCRE specification</title> </head> @@ -96,7 +96,7 @@ in the library. There is a single page for each triple of 8-bit/16-bit/32-bit functions. </p> -<table> +<table> <tr><td><a href="pcre_assign_jit_stack.html">pcre_assign_jit_stack</a></td> <td> Assign stack for JIT matching</td></tr> @@ -162,7 +162,7 @@ functions. <tr><td><a href="pcre_maketables.html">pcre_maketables</a></td> <td> Build character tables in current locale</td></tr> - + <tr><td><a href="pcre_pattern_to_host_byte_order.html">pcre_pattern_to_host_byte_order</a></td> <td> Convert compiled pattern to host byte order if necessary</td></tr> diff --git a/doc/html/pcre.html b/doc/html/pcre.html index 692f651..93b129e 100644 --- a/doc/html/pcre.html +++ b/doc/html/pcre.html @@ -62,7 +62,7 @@ The current implementation of PCRE corresponds approximately with Perl 5.12, including support for UTF-8/16/32 encoded strings and Unicode general category properties. However, UTF-8/16/32 and Unicode support has to be explicitly enabled; it is not the default. The Unicode tables correspond to Unicode -release 6.2.0. +release 6.3.0. </P> <P> In addition to the Perl-compatible matching function, PCRE contains an diff --git a/doc/html/pcre_compile.html b/doc/html/pcre_compile.html index b1d7429..95b4bec 100644 --- a/doc/html/pcre_compile.html +++ b/doc/html/pcre_compile.html @@ -65,6 +65,7 @@ The option bits are: PCRE_FIRSTLINE Force matching to be before newline PCRE_JAVASCRIPT_COMPAT JavaScript compatibility PCRE_MULTILINE ^ and $ match newlines within data + PCRE_NEVER_UTF Lock out UTF, e.g. via (*UTF) PCRE_NEWLINE_ANY Recognize any Unicode newline sequence PCRE_NEWLINE_ANYCRLF Recognize CR, LF, and CRLF as newline sequences @@ -73,6 +74,8 @@ The option bits are: PCRE_NEWLINE_LF Set LF as the newline sequence PCRE_NO_AUTO_CAPTURE Disable numbered capturing paren- theses (named ones available) + PCRE_NO_AUTO_POSSESS Disable auto-possessification + PCRE_NO_START_OPTIMIZE Disable match-time start optimizations PCRE_NO_UTF16_CHECK Do not check the pattern for UTF-16 validity (only relevant if PCRE_UTF16 is set) diff --git a/doc/html/pcre_compile2.html b/doc/html/pcre_compile2.html index a63b3ab..9cd56a2 100644 --- a/doc/html/pcre_compile2.html +++ b/doc/html/pcre_compile2.html @@ -69,6 +69,7 @@ The option bits are: PCRE_FIRSTLINE Force matching to be before newline PCRE_JAVASCRIPT_COMPAT JavaScript compatibility PCRE_MULTILINE ^ and $ match newlines within data + PCRE_NEVER_UTF Lock out UTF, e.g. via (*UTF) PCRE_NEWLINE_ANY Recognize any Unicode newline sequence PCRE_NEWLINE_ANYCRLF Recognize CR, LF, and CRLF as newline sequences @@ -77,6 +78,8 @@ The option bits are: PCRE_NEWLINE_LF Set LF as the newline sequence PCRE_NO_AUTO_CAPTURE Disable numbered capturing paren- theses (named ones available) + PCRE_NO_AUTO_POSSESS Disable auto-possessification + PCRE_NO_START_OPTIMIZE Disable match-time start optimizations PCRE_NO_UTF16_CHECK Do not check the pattern for UTF-16 validity (only relevant if PCRE_UTF16 is set) diff --git a/doc/html/pcre_config.html b/doc/html/pcre_config.html index fc10d18..bcdcdde 100644 --- a/doc/html/pcre_config.html +++ b/doc/html/pcre_config.html @@ -48,6 +48,7 @@ point to an unsigned long integer. The available codes are: target architecture for the JIT compiler, or NULL if there is no JIT support PCRE_CONFIG_LINK_SIZE Internal link size: 2, 3, or 4 + PCRE_CONFIG_PARENS_LIMIT Parentheses nesting limit PCRE_CONFIG_MATCH_LIMIT Internal resource limit PCRE_CONFIG_MATCH_LIMIT_RECURSION Internal recursion depth limit diff --git a/doc/html/pcreapi.html b/doc/html/pcreapi.html index 62859ca..abc3d26 100644 --- a/doc/html/pcreapi.html +++ b/doc/html/pcreapi.html @@ -484,6 +484,13 @@ the <a href="pcreposix.html"><b>pcreposix</b></a> documentation. <pre> + PCRE_CONFIG_PARENS_LIMIT +</pre> +The output is a long integer that gives the maximum depth of nesting 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 PCRE is +built; the default is 250. +<pre> PCRE_CONFIG_MATCH_LIMIT </pre> The output is a long integer that gives the default limit for the number of @@ -582,8 +589,9 @@ If the final argument, <i>tableptr</i>, is NULL, PCRE uses a default set of character tables that are built when PCRE is compiled, using the default C locale. Otherwise, <i>tableptr</i> must be an address that is the result of a call to <b>pcre_maketables()</b>. This value is stored with the compiled -pattern, and used again by <b>pcre_exec()</b>, unless another table pointer is -passed to it. For more discussion, see the section on locale support below. +pattern, and used again by <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b> when the +pattern is matched. For more discussion, see the section on locale support +below. </P> <P> This code fragment shows a typical straightforward call to <b>pcre_compile()</b>: @@ -668,12 +676,24 @@ documentation. <pre> PCRE_EXTENDED </pre> -If this bit is set, white space data characters in the pattern are totally -ignored except when escaped or inside a character class. White space does not -include the VT character (code 11). In addition, characters between an -unescaped # outside a character class and the next newline, inclusive, are also -ignored. This is equivalent to Perl's /x option, and it can be changed within a -pattern by a (?x) option setting. +If this bit is set, most white space characters in the pattern are totally +ignored except when escaped or inside a character class. However, white space +is not allowed within sequences such as (?> that introduce various +parenthesized subpatterns, nor within a numerical quantifier such as {1,3}. +However, ignorable white space is permitted between an item and a following +quantifier and between a quantifier and a following + that indicates +possessiveness. +</P> +<P> +White space did not used to include the VT character (code 11), because Perl +did not treat this character as white space. However, Perl changed at release +5.18, so PCRE followed at release 8.34, and VT is now treated as white space. +</P> +<P> +PCRE_EXTENDED also causes characters between an unescaped # outside a character +class and the next newline, inclusive, to be ignored. PCRE_EXTENDED is +equivalent to Perl's /x option, and it can be changed within a pattern by a +(?x) option setting. </P> <P> Which characters are interpreted as newlines is controlled by the options @@ -827,6 +847,15 @@ 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. <pre> + PCRE_NO_AUTO_POSSESS +</pre> +If this option is set, it disables "auto-possessification". This 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 of them 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 provided for testing purposes. +<pre> PCRE_NO_START_OPTIMIZE </pre> This is an option that acts at matching time; that is, it is really an option @@ -877,10 +906,10 @@ page. If an invalid UTF-8 sequence is found, <b>pcre_compile()</b> returns an error. If you already know that your pattern is valid, and you want to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid UTF-8 string as a pattern is -undefined. It may cause your program to crash. Note that this option can also -be passed to <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, to suppress the -validity checking of subject strings only. If the same string is being matched -many times, the option can be safely set for the second and subsequent +undefined. It may cause your program to crash or loop. Note that this option +can also be passed to <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>, to suppress +the validity checking of subject strings only. If the same string is being +matched many times, the option can be safely set for the second and subsequent matchings to improve performance. </P> <br><a name="SEC12" href="#TOC1">COMPILATION ERROR CODES</a><br> @@ -925,7 +954,7 @@ have fallen out of use. To avoid confusion, they have not been re-used. 31 POSIX collating elements are not supported 32 this version of PCRE is compiled without UTF support 33 [this code is not in use] - 34 character value in \x{...} sequence is too large + 34 character value in \x{} or \o{} is too large 35 invalid condition (?(0) 36 \C not allowed in lookbehind assertion 37 PCRE does not support \L, \l, \N{name}, \U, or \u @@ -973,6 +1002,12 @@ have fallen out of use. To avoid confusion, they have not been re-used. 75 name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN) 76 character value in \u.... sequence is too large 77 invalid UTF-32 string (specifically UTF-32) + 78 setting UTF is disabled by the application + 79 non-hex character in \x{} (closing brace missing?) + 80 non-octal character in \o{} (closing brace missing?) + 81 missing opening brace after \o + 82 parentheses are too deeply nested + 83 invalid range in character class </pre> The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may be used if the limits were changed when PCRE was built. @@ -1103,15 +1138,18 @@ There is a longer discussion of PCRE_NO_START_OPTIMIZE <P> PCRE handles caseless matching, and determines whether characters are letters, digits, or whatever, by reference to a set of tables, indexed by character -value. When running in UTF-8 mode, this applies only to characters -with codes less than 128. By default, higher-valued codes never match escapes -such as \w or \d, but they can be tested with \p if PCRE is built with -Unicode character property support. Alternatively, the PCRE_UCP option can be -set at compile time; this causes \w and friends to use Unicode property -support instead of built-in tables. The use of locales with Unicode is -discouraged. If you are handling characters with codes greater than 128, you -should either use UTF-8 and Unicode, or use locales, but not try to mix the -two. +code point. When running in UTF-8 mode, or in the 16- or 32-bit libraries, this +applies only to characters with code points less than 256. By default, +higher-valued code points never match escapes such as \w or \d. However, if +PCRE is built with Unicode property support, all characters can be tested with +\p and \P, or, alternatively, the PCRE_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. +</P> +<P> +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. </P> <P> PCRE contains an internal set of tables that are used when the final argument @@ -1129,10 +1167,10 @@ for this locale support is expected to die away. <P> External tables are built by calling the <b>pcre_maketables()</b> function, which has no arguments, in the relevant locale. The result can then be passed -to <b>pcre_compile()</b> or <b>pcre_exec()</b> as often as necessary. 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: +to <b>pcre_compile()</b> as often as necessary. 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: <pre> setlocale(LC_CTYPE, "fr_FR"); tables = pcre_maketables(); @@ -1150,16 +1188,20 @@ needed. <P> The pointer that is passed to <b>pcre_compile()</b> is saved with the compiled pattern, and the same tables are used via this pointer by <b>pcre_study()</b> -and normally also by <b>pcre_exec()</b>. Thus, by default, for any single +and also by <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b>. Thus, for any single pattern, compilation, studying and matching all happen in the same locale, but -different patterns can be compiled in different locales. +different patterns can be processed in different locales. </P> <P> It is possible to pass a table pointer or NULL (indicating the use of the -internal tables) to <b>pcre_exec()</b>. Although not intended for this purpose, -this facility could be used to match a pattern in a different locale from the -one in which it was compiled. Passing table pointers at run time is discussed -below in the section on matching a pattern. +internal tables) to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> (see the +discussion below in the section on matching a pattern). This facility is +provided for use with pre-compiled patterns that have been saved and reloaded. +Character tables are not saved with patterns, so if a non-standard table was +used at compile time, it must be provided again when the reloaded pattern is +matched. Attempting to use this facility to match a pattern in a different +locale from the one in which it was compiled is likely to lead to anomalous +(usually incorrect) results. <a name="infoaboutpattern"></a></P> <br><a name="SEC15" href="#TOC1">INFORMATION ABOUT A PATTERN</a><br> <P> @@ -1305,10 +1347,15 @@ is -1. </P> <P> Since for the 32-bit library using the non-UTF-32 mode, this function is unable -to return the full 32-bit range of the character, this value is deprecated; +to return the full 32-bit range of characters, this value is deprecated; instead the PCRE_INFO_REQUIREDCHARFLAGS and PCRE_INFO_REQUIREDCHAR values should be used. <pre> + PCRE_INFO_MATCH_EMPTY +</pre> +Return 1 if the pattern can match an empty string, otherwise 0. The fourth +argument should point to an <b>int</b> variable. +<pre> PCRE_INFO_MATCHLIMIT </pre> If the pattern set a match limit by including an item of the form @@ -1366,16 +1413,18 @@ contains the parenthesis number. The rest of the entry is the corresponding name, zero terminated. </P> <P> -The names are in alphabetical order. Duplicate names may appear if (?| is used -to create multiple groups with the same number, as described in the +The names are in alphabetical order. If (?| is used to create multiple groups +with the same number, as described in the <a href="pcrepattern.html#dupsubpatternnumber">section on duplicate subpattern numbers</a> in the <a href="pcrepattern.html"><b>pcrepattern</b></a> -page. Duplicate names for subpatterns with different numbers are permitted only -if PCRE_DUPNAMES is set. In all cases of duplicate names, 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. +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 PCRE_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. </P> <P> As a simple example of the name/number table, consider the following pattern @@ -1489,30 +1538,14 @@ returned. For anchored patterns, 0 is returned. <pre> PCRE_INFO_FIRSTCHARACTER </pre> -Return the fixed first character value, if PCRE_INFO_FIRSTCHARACTERFLAGS -returned 1; otherwise returns 0. The fourth argument should point to an -<b>uint_t</b> variable. +Return the fixed first character value in the situation where +PCRE_INFO_FIRSTCHARACTERFLAGS returns 1; otherwise return 0. The fourth +argument should point to an <b>uint_t</b> variable. </P> <P> 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. -</P> -<P> -If there is no fixed first value, and if either -<br> -<br> -(a) the pattern was compiled with the PCRE_MULTILINE option, and every branch -starts with "^", or -<br> -<br> -(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not set -(if it were set, the pattern would be anchored), -<br> -<br> --1 is returned, indicating that the pattern matches only at the start of a -subject string or after any newline within the string. Otherwise -2 is -returned. For anchored patterns, -2 is returned. <pre> PCRE_INFO_REQUIREDCHARFLAGS </pre> @@ -1725,17 +1758,22 @@ and is described in the documentation. </P> <P> -The <i>tables</i> field is used to pass a character tables pointer to -<b>pcre_exec()</b>; this overrides the value that is stored with the compiled -pattern. A non-NULL value is stored with the compiled pattern only if custom -tables were supplied to <b>pcre_compile()</b> via its <i>tableptr</i> argument. -If NULL is passed to <b>pcre_exec()</b> using this mechanism, it forces PCRE's -internal tables to be used. This facility is helpful when re-using patterns -that have been saved after compiling with an external set of tables, because -the external tables might be at a different address when <b>pcre_exec()</b> is -called. See the +The <i>tables</i> field is provided for use with patterns that have been +pre-compiled using custom character tables, saved to disc or elsewhere, and +then reloaded, because the tables that were used to compile a pattern are not +saved with it. See the <a href="pcreprecompile.html"><b>pcreprecompile</b></a> -documentation for a discussion of saving compiled patterns for later use. +documentation for a discussion of saving compiled patterns for later use. If +NULL is passed using this mechanism, it forces PCRE's internal tables to be +used. +</P> +<P> +<b>Warning:</b> The tables that <b>pcre_exec()</b> uses must be the same as those +that were used when the pattern was compiled. If this is not the case, the +behaviour of <b>pcre_exec()</b> is undefined. Therefore, when a pattern is +compiled and matched in the same process, this field should never be set. In +this (the most common) case, the correct table pointer is automatically passed +with the compiled pattern from <b>pcre_compile()</b> to <b>pcre_exec()</b>. </P> <P> If PCRE_EXTRA_MARK is set in the <i>flags</i> field, the <i>mark</i> field must @@ -1953,7 +1991,7 @@ all the matches in a single subject string. However, you should be sure that the value of <i>startoffset</i> points to the start of a character (or the end of the subject). When PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid string as a subject or an invalid value of <i>startoffset</i> is -undefined. Your program may crash. +undefined. Your program may crash or loop. <pre> PCRE_PARTIAL_HARD PCRE_PARTIAL_SOFT @@ -2786,6 +2824,15 @@ matching string is given first. If there were too many matches to fit into the longest matches. Unlike <b>pcre_exec()</b>, <b>pcre_dfa_exec()</b> can use the entire <i>ovector</i> for returning matched strings. </P> +<P> +NOTE: PCRE's "auto-possessification" optimization usually applies to character +repeats at the end of a pattern (as well as internally). For example, the +pattern "a\d+" is compiled as if it were "a\d++" because there is no point +even considering the possibility of backtracking into the repeated digits. For +DFA matching, this means that only one possible match is found. If you really +do want multiple matches in such cases, either use an ungreedy repeat +("a\d+?") or set the PCRE_NO_AUTO_POSSESS option when compiling. +</P> <br><b> Error returns from <b>pcre_dfa_exec()</b> </b><br> @@ -2852,7 +2899,7 @@ Cambridge CB2 3QH, England. </P> <br><a name="SEC26" href="#TOC1">REVISION</a><br> <P> -Last updated: 12 June 2013 +Last updated: 12 November 2013 <br> Copyright © 1997-2013 University of Cambridge. <br> diff --git a/doc/html/pcrecallout.html b/doc/html/pcrecallout.html index 7233bb6..53a937f 100644 --- a/doc/html/pcrecallout.html +++ b/doc/html/pcrecallout.html @@ -77,15 +77,50 @@ independent groups). Automatic callouts can be used for tracking the progress of pattern matching. The <a href="pcretest.html"><b>pcretest</b></a> -command has an option that sets automatic callouts; when it is used, the output -indicates how the pattern is matched. This is useful information when you are -trying to optimize the performance of a particular pattern. +program has a pattern qualifier (/C) that sets automatic callouts; when it is +used, the output indicates how the pattern is being matched. This is useful +information when you are trying to optimize the performance of a particular +pattern. </P> <br><a name="SEC3" href="#TOC1">MISSING CALLOUTS</a><br> <P> -You should be aware that, because of optimizations in the way PCRE matches -patterns by default, callouts sometimes do not happen. For example, if the -pattern is +You should be aware that, because of optimizations in the way PCRE compiles and +matches patterns, callouts sometimes do not happen exactly as you might expect. +</P> +<P> +At compile time, PCRE "auto-possessifies" repeated items when it knows that +what follows cannot be part of the repeat. For example, a+[bc] is compiled as +if it were a++[bc]. The <b>pcretest</b> output when this pattern is anchored and +then applied with automatic callouts to the string "aaaa" is: +<pre> + --->aaaa + +0 ^ ^ + +1 ^ a+ + +3 ^ ^ [bc] + No match +</pre> +This indicates that when matching [bc] fails, there is no backtracking into a+ +and therefore the callouts that would be taken for the backtracks do not occur. +You can disable the auto-possessify feature by passing PCRE_NO_AUTO_POSSESS +to <b>pcre_compile()</b>, or starting the pattern with (*NO_AUTO_POSSESS). If +this is done in <b>pcretest</b> (using the /O qualifier), the output changes to +this: +<pre> + --->aaaa + +0 ^ ^ + +1 ^ a+ + +3 ^ ^ [bc] + +3 ^ ^ [bc] + +3 ^ ^ [bc] + +3 ^^ [bc] + No match +</pre> +This time, when matching [bc] fails, the matcher backtracks into a+ and tries +again, repeatedly, until a+ itself fails. +</P> +<P> +Other optimizations that provide fast "no match" results also affect callouts. +For example, if the pattern is <pre> ab(?C4)cd </pre> @@ -109,11 +144,11 @@ callouts such as the example above are obeyed. <br><a name="SEC4" href="#TOC1">THE CALLOUT INTERFACE</a><br> <P> During matching, when PCRE reaches a callout point, the external function -defined by <i>pcre_callout</i> or <i>pcre[16|32]_callout</i> is called -(if it is set). This applies to both normal and DFA matching. The only -argument to the callout function is a pointer to a <b>pcre_callout</b> -or <b>pcre[16|32]_callout</b> block. -These structures contains the following fields: +defined by <i>pcre_callout</i> or <i>pcre[16|32]_callout</i> is called (if it is +set). This applies to both normal and DFA matching. The only argument to the +callout function is a pointer to a <b>pcre_callout</b> or +<b>pcre[16|32]_callout</b> block. These structures contains the following +fields: <pre> int <i>version</i>; int <i>callout_number</i>; @@ -242,7 +277,7 @@ Cambridge CB2 3QH, England. </P> <br><a name="SEC7" href="#TOC1">REVISION</a><br> <P> -Last updated: 03 March 2013 +Last updated: 12 November 2013 <br> Copyright © 1997-2013 University of Cambridge. <br> diff --git a/doc/html/pcrecompat.html b/doc/html/pcrecompat.html index 14e20c5..3e62266 100644 --- a/doc/html/pcrecompat.html +++ b/doc/html/pcrecompat.html @@ -138,18 +138,24 @@ an error is given at compile time. <P> 15. Perl recognizes comments in some places that PCRE does not, for example, between the ( and ? at the start of a subpattern. If the /x modifier is set, -Perl allows white space between ( and ? but PCRE never does, even if the -PCRE_EXTENDED option is set. +Perl allows white space between ( and ? (though current Perls warn that this is +deprecated) but PCRE never does, even if the PCRE_EXTENDED option is set. </P> <P> -16. In PCRE, the upper/lower case character properties Lu and Ll are not +16. Perl, when in warning mode, gives warnings for character classes such as +[A-\d] or [a-[:digit:]]. It then treats the hyphens as literals. PCRE has no +warning features, so it gives an error in these cases because they are almost +certainly user mistakes. +</P> +<P> +17. In PCRE, the upper/lower case character properties Lu and Ll are not affected when case-independent matching is specified. For example, \p{Lu} always matches an upper case letter. I think Perl has changed in this respect; in the release at the time of writing (5.16), \p{Lu} and \p{Ll} match all letters, regardless of case, when case independence is specified. </P> <P> -17. PCRE provides some extensions to the Perl regular expression facilities. +18. PCRE provides some extensions to the Perl regular expression facilities. Perl 5.10 includes new features that are not in earlier versions of Perl, some of which (such as named parentheses) have been in PCRE for some time. This list is with respect to Perl 5.10: @@ -220,7 +226,7 @@ Cambridge CB2 3QH, England. REVISION </b><br> <P> -Last updated: 19 March 2013 +Last updated: 10 November 2013 <br> Copyright © 1997-2013 University of Cambridge. <br> diff --git a/doc/html/pcrelimits.html b/doc/html/pcrelimits.html index b83a801..ee5ebf0 100644 --- a/doc/html/pcrelimits.html +++ b/doc/html/pcrelimits.html @@ -21,9 +21,10 @@ practice be relevant. </P> <P> The maximum length of a compiled pattern is approximately 64K data units (bytes -for the 8-bit library, 32-bit units for the 32-bit library, and 32-bit units for -the 32-bit library) if PCRE is compiled with the default internal linkage size -of 2 bytes. If you want to process regular expressions that are truly enormous, +for the 8-bit library, 16-bit units for the 16-bit library, and 32-bit units for +the 32-bit library) if PCRE is compiled with the default internal linkage size, +which is 2 bytes for the 8-bit and 16-bit libraries, and 4 bytes for the 32-bit +library. If you want to process regular expressions that are truly enormous, you can compile PCRE with an internal linkage size of 3 or 4 (when building the 16-bit or 32-bit library, 3 is rounded up to 4). See the <b>README</b> file in the source distribution and the @@ -36,7 +37,10 @@ All values in repeating quantifiers must be less than 65536. </P> <P> There is no limit to the number of parenthesized subpatterns, but there can be -no more than 65535 capturing subpatterns. +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 +order to limit the amount of system stack used at compile time. The limit can +be specified when PCRE is built; the default is 250. </P> <P> There is a limit to the number of forward references to subsequent subpatterns @@ -50,7 +54,7 @@ maximum number of named subpatterns is 10000. </P> <P> The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or (*THEN) verb -is 255 for the 8-bit library and 65535 for the 16-bit and 32-bit library. +is 255 for the 8-bit library and 65535 for the 16-bit and 32-bit libraries. </P> <P> The maximum length of a subject string is the largest positive number that an @@ -77,9 +81,9 @@ Cambridge CB2 3QH, England. REVISION </b><br> <P> -Last updated: 04 May 2012 +Last updated: 05 November 2013 <br> -Copyright © 1997-2012 University of Cambridge. +Copyright © 1997-2013 University of Cambridge. <br> <p> Return to the <a href="index.html">PCRE index page</a>. diff --git a/doc/html/pcrematching.html b/doc/html/pcrematching.html index f185431..a1af39b 100644 --- a/doc/html/pcrematching.html +++ b/doc/html/pcrematching.html @@ -126,6 +126,15 @@ character of the subject. The algorithm does not automatically move on to find matches that start at later positions. </P> <P> +PCRE's "auto-possessification" optimization usually applies to character +repeats at the end of a pattern (as well as internally). For example, the +pattern "a\d+" is compiled as if it were "a\d++" because there is no point +even considering the possibility of backtracking into the repeated digits. For +DFA matching, this means that only one possible match is found. If you really +do want multiple matches in such cases, either use an ungreedy repeat +("a\d+?") or set the PCRE_NO_AUTO_POSSESS option when compiling. +</P> +<P> There are a number of features of PCRE regular expressions that are not supported by the alternative matching algorithm. They are as follows: </P> @@ -224,7 +233,7 @@ Cambridge CB2 3QH, England. </P> <br><a name="SEC8" href="#TOC1">REVISION</a><br> <P> -Last updated: 08 January 2012 +Last updated: 12 November 2013 <br> Copyright © 1997-2012 University of Cambridge. <br> diff --git a/doc/html/pcrepartial.html b/doc/html/pcrepartial.html index 98d34f0..4faeafc 100644 --- a/doc/html/pcrepartial.html +++ b/doc/html/pcrepartial.html @@ -306,6 +306,16 @@ not retain the previously partially-matched string. It is up to the calling program to do that if it needs to. </P> <P> +That means that, for an unanchored pattern, if a continued match fails, it is +not possible to try again at a new starting point. All this facility is capable +of doing is continuing with the previous match attempt. In the previous +example, if the second set of data is "ug23" the result is no match, even +though there would be a match for "aug23" if the entire string were given at +once. Depending on the application, this may or may not be what you want. +The only way to allow for starting again at the next character is to retain the +matched part of the subject and try a new complete match. +</P> +<P> You can set the PCRE_PARTIAL_SOFT or PCRE_PARTIAL_HARD options with PCRE_DFA_RESTART to continue partial matching over multiple segments. This facility can be used to pass very long subject strings to the DFA matching @@ -490,7 +500,7 @@ Cambridge CB2 3QH, England. </P> <br><a name="SEC11" href="#TOC1">REVISION</a><br> <P> -Last updated: 20 February 2013 +Last updated: 02 July 2013 <br> Copyright © 1997-2013 University of Cambridge. <br> diff --git a/doc/html/pcrepattern.html b/doc/html/pcrepattern.html index 7e837e5..7c133f1 100644 --- a/doc/html/pcrepattern.html +++ b/doc/html/pcrepattern.html @@ -116,21 +116,33 @@ appearance causes an error. Unicode property support </b><br> <P> -Another special sequence that may appear at the start of a pattern is -<pre> - (*UCP) -</pre> +Another special sequence that may appear at the start of a pattern is (*UCP). This has the same effect as setting the PCRE_UCP option: it causes sequences such as \d and \w to use Unicode properties to determine character types, instead of recognizing only characters with codes less than 128 via a lookup table. </P> <br><b> +Disabling auto-possessification +</b><br> +<P> +If a pattern starts with (*NO_AUTO_POSSESS), it has the same effect as setting +the PCRE_NO_AUTO_POSSESS option at compile time. This stops PCRE from making +quantifiers possessive when what follows cannot match the repeated item. For +example, by default a+b is treated as a++b. For more details, see the +<a href="pcreapi.html"><b>pcreapi</b></a> +documentation. +</P> +<br><b> Disabling start-up optimizations </b><br> <P> If a pattern starts with (*NO_START_OPT), it has the same effect as setting the -PCRE_NO_START_OPTIMIZE option either at compile or matching time. +PCRE_NO_START_OPTIMIZE option either at compile or matching time. This disables +several optimizations for quickly reaching "no match" results. For more +details, see the +<a href="pcreapi.html"><b>pcreapi</b></a> +documentation. <a name="newlines"></a></P> <br><b> Newline conventions @@ -193,10 +205,10 @@ pattern of the form (*LIMIT_RECURSION=d) </pre> where d is any number of decimal digits. However, the value of the setting must -be less than the value set by the caller of <b>pcre_exec()</b> for it to have -any effect. In other words, the pattern writer can lower the limit set by the -programmer, but not raise it. If there is more than one setting of one of these -limits, the lower value is used. +be less than the value set (or defaulted) by the caller of <b>pcre_exec()</b> +for it to have any effect. In other words, the pattern writer can lower the +limits set by the programmer, but not raise them. If there is more than one +setting of one of these limits, the lower value is used. </P> <br><a name="SEC3" href="#TOC1">EBCDIC CHARACTER CODES</a><br> <P> @@ -283,10 +295,11 @@ backslash. All other characters (in particular, those whose codepoints are greater than 127) are treated as literals. </P> <P> -If a pattern is compiled with the PCRE_EXTENDED option, white space in the -pattern (other than in a character class) and characters between a # outside -a character class and the next newline are ignored. An escaping backslash can -be used to include a white space or # character as part of the pattern. +If a pattern is compiled with the PCRE_EXTENDED option, most white space in the +pattern (other than in a character class), and characters between a # outside a +character class and the next newline, inclusive, are ignored. An escaping +backslash can be used to include a white space or # character as part of the +pattern. </P> <P> If you want to remove the special meaning from a sequence of characters, you @@ -324,7 +337,9 @@ one of the following escape sequences than the binary character it represents: \n linefeed (hex 0A) \r carriage return (hex 0D) \t tab (hex 09) + \0dd character with octal code 0dd \ddd character with octal code ddd, or back reference + \o{ddd..} character with octal code ddd.. \xhh character with hex code hh \x{hhh..} character with hex code hhh.. (non-JavaScript mode) \uhhhh character with hex code hhhh (JavaScript mode only) @@ -347,42 +362,6 @@ the EBCDIC letters are disjoint, \cZ becomes hex 29 (Z is E9), and other characters also generate different values. </P> <P> -By default, after \x, from zero to two hexadecimal digits are read (letters -can be in upper or lower case). Any number of hexadecimal digits may appear -between \x{ and }, but the character code is constrained as follows: -<pre> - 8-bit non-UTF mode less than 0x100 - 8-bit UTF-8 mode less than 0x10ffff and a valid codepoint - 16-bit non-UTF mode less than 0x10000 - 16-bit UTF-16 mode less than 0x10ffff and a valid codepoint - 32-bit non-UTF mode less than 0x80000000 - 32-bit UTF-32 mode less than 0x10ffff and a valid codepoint -</pre> -Invalid Unicode codepoints are the range 0xd800 to 0xdfff (the so-called -"surrogate" codepoints), and 0xffef. -</P> -<P> -If characters other than hexadecimal digits appear between \x{ and }, or if -there is no terminating }, this form of escape is not recognized. Instead, the -initial \x will be interpreted as a basic hexadecimal escape, with no -following digits, giving a character whose value is zero. -</P> -<P> -If the PCRE_JAVASCRIPT_COMPAT option is set, the interpretation of \x is -as just described only when it is followed by two hexadecimal digits. -Otherwise, it matches a literal "x" character. In JavaScript mode, support for -code points greater than 256 is provided by \u, which must be followed by -four hexadecimal digits; otherwise it matches a literal "u" character. -Character codes specified by \u in JavaScript mode are constrained in the same -was as those specified by \x in non-JavaScript mode. -</P> -<P> -Characters whose value is less than 256 can be defined by either of the two -syntaxes for \x (or by \u in JavaScript mode). There is no difference in the -way they are handled. For example, \xdc is exactly the same as \x{dc} (or -\u00dc in JavaScript mode). -</P> -<P> After \0 up to two further octal digits are read. If there are fewer than two digits, just those that are present are used. Thus the sequence \0\x\07 specifies two binary zeros followed by a BEL character (code value 7). Make @@ -390,9 +369,23 @@ sure you supply two digits after the initial zero if the pattern character that follows is itself an octal digit. </P> <P> -The handling of a backslash followed by a digit other than 0 is complicated. -Outside a character class, PCRE reads it and any following digits as a decimal -number. If the number is less than 10, or if there have been at least that many +The escape \o must be followed by a sequence of octal digits, enclosed in +braces. An error occurs if this is not the case. This escape is a recent +addition to Perl; it provides way of specifying character code points as octal +numbers greater than 0777, and it also allows octal numbers and back references +to be unambiguously specified. +</P> +<P> +For greater clarity and unambiguity, it is best to avoid following \ by a +digit greater than zero. Instead, use \o{} or \x{} to specify character +numbers, and \g{} to specify back references. The following paragraphs +describe the old, ambiguous syntax. +</P> +<P> +The handling of a backslash followed by a digit other than 0 is complicated, +and Perl has changed in recent releases, causing PCRE also to change. Outside a +character class, PCRE reads the digit and any following digits as a decimal +number. If the number is less than 8, or if there have been at least that many previous capturing left parentheses in the expression, the entire sequence is taken as a <i>back reference</i>. A description of how this works is given <a href="#backreferences">later,</a> @@ -400,12 +393,11 @@ following the discussion of <a href="#subpattern">parenthesized subpatterns.</a> </P> <P> -Inside a character class, or if the decimal number is greater than 9 and there -have not been that many capturing subpatterns, PCRE re-reads up to three octal -digits following the backslash, and uses them to generate a data character. Any -subsequent digits stand for themselves. The value of the character is -constrained in the same way as characters specified in hexadecimal. -For example: +Inside a character class, or if the decimal number following \ is greater than +7 and there have not been that many capturing subpatterns, PCRE handles \8 and +\9 as the literal characters "8" and "9", and otherwise re-reads up to three +octal digits following the backslash, using them to generate a data character. +Any subsequent digits stand for themselves. For example: <pre> \040 is another way of writing an ASCII space \40 is the same, provided there are fewer than 40 previous capturing subpatterns @@ -415,12 +407,53 @@ For example: \0113 is a tab followed by the character "3" \113 might be a back reference, otherwise the character with octal code 113 \377 might be a back reference, otherwise the value 255 (decimal) - \81 is either a back reference, or a binary zero followed by the two characters "8" and "1" + \81 is either a back reference, or the two characters "8" and "1" </pre> -Note that octal values of 100 or greater must not be introduced by a leading -zero, because no more than three octal digits are ever read. +Note that octal values of 100 or greater that are specified using this syntax +must not be introduced by a leading zero, because no more than three octal +digits are ever read. +</P> +<P> +By default, after \x that is not followed by {, from zero to two hexadecimal +digits are read (letters can be in upper or lower case). Any number of +hexadecimal digits may appear between \x{ and }. If a character other than +a hexadecimal digit appears between \x{ and }, or if there is no terminating +}, an error occurs. </P> <P> +If the PCRE_JAVASCRIPT_COMPAT option is set, the interpretation of \x is +as just described only when it is followed by two hexadecimal digits. +Otherwise, it matches a literal "x" character. In JavaScript mode, support for +code points greater than 256 is provided by \u, which must be followed by +four hexadecimal digits; otherwise it matches a literal "u" character. +</P> +<P> +Characters whose value is less than 256 can be defined by either of the two +syntaxes for \x (or by \u in JavaScript mode). There is no difference in the +way they are handled. For example, \xdc is exactly the same as \x{dc} (or +\u00dc in JavaScript mode). +</P> +<br><b> +Constraints on character values +</b><br> +<P> +Characters that are specified using octal or hexadecimal numbers are +limited to certain values, as follows: +<pre> + 8-bit non-UTF mode less than 0x100 + 8-bit UTF-8 mode less than 0x10ffff and a valid codepoint + 16-bit non-UTF mode less than 0x10000 + 16-bit UTF-16 mode less than 0x10ffff and a valid codepoint + 32-bit non-UTF mode less than 0x100000000 + 32-bit UTF-32 mode less than 0x10ffff and a valid codepoint +</pre> +Invalid Unicode codepoints are the range 0xd800 to 0xdfff (the so-called +"surrogate" codepoints), and 0xffef. +</P> +<br><b> +Escape sequences in character classes +</b><br> +<P> All the sequences that define a single character value can be used both inside and outside character classes. In addition, inside a character class, \b is interpreted as the backspace character (hex 08). @@ -498,11 +531,13 @@ matching point is at the end of the subject string, all of them fail, because there is no character to match. </P> <P> -For compatibility with Perl, \s does not match the VT character (code 11). -This makes it different from the the POSIX "space" class. The \s characters -are HT (9), LF (10), FF (12), CR (13), and space (32). If "use locale;" is -included in a Perl script, \s may match the VT character. In PCRE, it never -does. +For compatibility with Perl, \s did not used to match the VT character (code +11), which made it different from the the POSIX "space" class. However, Perl +added VT at release 5.18, and PCRE followed suit at release 8.34. The default +\s characters are now HT (9), LF (10), VT (11), FF (12), CR (13), and space +(32), which are defined as white space in the "C" locale. This list may vary if +locale-specific matching is taking place; in particular, in some locales the +"non-breaking space" character (\xA0) is recognized as white space. </P> <P> A "word" character is an underscore or any character that is a letter or digit. @@ -513,21 +548,23 @@ place (see in the <a href="pcreapi.html"><b>pcreapi</b></a> page). For example, in a French locale such as "fr_FR" in Unix-like systems, -or "french" in Windows, some character codes greater than 128 are used for +or "french" in Windows, some character codes greater than 127 are used for accented letters, and these are then matched by \w. The use of locales with Unicode is discouraged. </P> <P> -By default, in a UTF mode, characters with values greater than 128 never match -\d, \s, or \w, and always match \D, \S, and \W. These sequences retain -their original meanings from before UTF support was available, mainly for -efficiency reasons. However, if PCRE is compiled with Unicode property support, -and the PCRE_UCP option is set, the behaviour is changed so that Unicode -properties are used to determine character types, as follows: +By default, characters whose code points are greater than 127 never match \d, +\s, or \w, and always match \D, \S, and \W, although this may vary for +characters in the range 128-255 when locale-specific matching is happening. +These escape sequences retain their original meanings from before Unicode +support was available, mainly for efficiency reasons. If PCRE is compiled with +Unicode property support, and the PCRE_UCP option is set, the behaviour is +changed so that Unicode properties are used to determine character types, as +follows: <pre> - \d any character that \p{Nd} matches (decimal digit) - \s any character that \p{Z} matches, plus HT, LF, FF, CR - \w any character that \p{L} or \p{N} matches, plus underscore + \d any character that matches \p{Nd} (decimal digit) + \s any character that matches \p{Z} or \h or \v + \w any character that matches \p{L} or \p{N}, plus underscore </pre> The upper case escapes match the inverse sets of characters. Note that \d matches only decimal digits, whereas \w matches any Unicode digit, as well as @@ -538,7 +575,7 @@ is noticeably slower when PCRE_UCP is set. <P> The sequences \h, \H, \v, and \V are features that were added to Perl at release 5.10. In contrast to the other sequences, which match only ASCII -characters by default, these always match certain high-valued codepoints, +characters by default, these always match certain high-valued code points, whether or not PCRE_UCP is set. The horizontal space characters are: <pre> U+0009 Horizontal tab (HT) @@ -913,9 +950,9 @@ PCRE's additional properties <P> As well as the standard Unicode properties described above, PCRE supports four more that make it possible to convert traditional escape sequences such as \w -and \s and POSIX character classes to use Unicode properties. PCRE uses these -non-standard, non-Perl properties internally when PCRE_UCP is set. However, -they may also be used explicitly. These properties are: +and \s to use Unicode properties. PCRE uses these non-standard, non-Perl +properties internally when PCRE_UCP is set. However, they may also be used +explicitly. These properties are: <pre> Xan Any alphanumeric character Xps Any POSIX space character @@ -925,8 +962,9 @@ they may also be used explicitly. These properties are: Xan matches characters that have either the L (letter) or the N (number) property. Xps matches the characters tab, linefeed, vertical tab, form feed, or carriage return, and any other character that has the Z (separator) property. -Xsp is the same as Xps, except that vertical tab is excluded. Xwd matches the -same characters as Xan, plus underscore. +Xsp is the same as Xps; it used to exclude vertical tab, for Perl +compatibility, but Perl changed, and so PCRE followed at release 8.34. Xwd +matches the same characters as Xan, plus underscore. </P> <P> There is another non-standard property, Xuc, which matches any character that @@ -1218,7 +1256,9 @@ The minus (hyphen) character can be used to specify a range of characters in a character class. For example, [d-m] matches any letter between d and m, inclusive. If a minus character is required in a class, it must be escaped with a backslash or appear in a position where it cannot be interpreted as -indicating a range, typically as the first or last character in the class. +indicating a range, typically as the first or last character in the class, or +immediately after a range. For example, [b-d-z] matches letters in the range b +to d, a hyphen character, or z. </P> <P> It is not possible to have the literal character "]" as the end character of a @@ -1230,6 +1270,12 @@ followed by two other characters. The octal or hexadecimal representation of "]" can also be used to end a range. </P> <P> +An error is generated if a POSIX character class (see below) or an escape +sequence other than one that defines a single character appears at a point +where a range ending character is expected. For example, [z-\xff] is valid, +but [A-\d] and [A-[:digit:]] are not. +</P> +<P> Ranges operate in the collating sequence of character values. They can also be used for characters specified numerically, for example [\000-\037]. Ranges can include any characters that are valid for the current mode. @@ -1294,15 +1340,17 @@ are: lower lower case letters print printing characters, including space punct printing characters, excluding letters and digits and space - space white space (not quite the same as \s) + space white space (the same as \s from PCRE 8.34) upper upper case letters word "word" characters (same as \w) xdigit hexadecimal digits </pre> -The "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13), and -space (32). Notice that this list includes the VT character (code 11). This -makes "space" different to \s, which does not include VT (for Perl -compatibility). +The default "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13), +and space (32). If locale-specific matching is taking place, there may be +additional space characters. "Space" used to be different to \s, which did not +include VT, for Perl compatibility. However, Perl changed at release 5.18, and +PCRE followed at release 8.34. "Space" and \s now match the same set of +characters. </P> <P> The name "word" is a Perl extension, and "blank" is a GNU extension from Perl @@ -1316,11 +1364,11 @@ syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not supported, and an error is given if they are encountered. </P> <P> -By default, in UTF modes, characters with values greater than 128 do not match -any of the POSIX character classes. However, if the PCRE_UCP option is passed -to <b>pcre_compile()</b>, some of the classes are changed so that Unicode -character properties are used. This is achieved by replacing the POSIX classes -by other sequences, as follows: +By default, characters with values greater than 128 do not match any of the +POSIX character classes. However, if the PCRE_UCP option is passed to +<b>pcre_compile()</b>, some of the classes are changed so that Unicode character +properties are used. This is achieved by replacing certain POSIX classes by +other sequences, as follows: <pre> [:alnum:] becomes \p{Xan} [:alpha:] becomes \p{L} @@ -1331,9 +1379,35 @@ by other sequences, as follows: [:upper:] becomes \p{Lu} [:word:] becomes \p{Xwd} </pre> -Negated versions, such as [:^alpha:] use \P instead of \p. The other POSIX -classes are unchanged, and match only characters with code points less than -128. +Negated versions, such as [:^alpha:] use \P instead of \p. Three other POSIX +classes are handled specially in UCP mode: +</P> +<P> +[:graph:] +This matches characters that have glyphs that mark the page when printed. In +Unicode property terms, it matches all characters with the L, M, N, P, S, or Cf +properties, except for: +<pre> + U+061C Arabic Letter Mark + U+180E Mongolian Vowel Separator + U+2066 - U+2069 Various "isolate"s + +</PRE> +</P> +<P> +[:print:] +This matches the same characters as [:graph:] plus space characters that are +not controls, that is, characters with the Zs property. +</P> +<P> +[:punct:] +This matches all characters that have the Unicode P (punctuation) property, +plus those characters whose code points are less than 128 that have the S +(Symbol) property. +</P> +<P> +The other POSIX classes are unchanged, and match only characters with code +points less than 128. </P> <br><a name="SEC11" href="#TOC1">VERTICAL BAR</a><br> <P> @@ -1535,11 +1609,12 @@ and can be made by name as well as by number. </P> <P> -Names consist of up to 32 alphanumeric characters and underscores. Named -capturing parentheses are still allocated numbers as well as names, exactly as -if the names were not present. The PCRE API provides function calls for -extracting the name-to-number translation table from a compiled pattern. There -is also a convenience function for extracting a captured substring by name. +Names consist of up to 32 alphanumeric characters and underscores, but must +start with a non-digit. Named capturing parentheses are still allocated numbers +as well as names, exactly as if the names were not present. The PCRE API +provides function calls for extracting the name-to-number translation table +from a compiled pattern. There is also a convenience function for extracting a +captured substring by name. </P> <P> By default, a name must be unique within a pattern, but it is possible to relax @@ -1568,9 +1643,23 @@ matched. This saves searching to find which numbered subpattern it was. </P> <P> If you make a back reference to a non-unique named subpattern from elsewhere in -the pattern, the one that corresponds to the first occurrence of the name is -used. In the absence of duplicate numbers (see the previous section) this is -the one with the lowest number. If you use a named reference in a condition +the pattern, the subpatterns to which the name refers are checked in the order +in which they appear in the overall pattern. The first one that is set is used +for the reference. For example, this pattern matches both "foofoo" and +"barbar" but not "foobar" or "barfoo": +<pre> + (?:(?<n>foo)|(?<n>bar))\k<n> + +</PRE> +</P> +<P> +If you make a subroutine call to a non-unique named subpattern, the one that +corresponds to the first occurrence of the name is used. In the absence of +duplicate numbers (see the previous section) this is the one with the lowest +number. +</P> +<P> +If you use a named reference in a condition test (see the <a href="#conditions">section about conditions</a> below), either to check whether a subpattern has matched, or to check for @@ -1585,8 +1674,9 @@ documentation. <b>Warning:</b> You cannot use different names to distinguish between two subpatterns with the same number because PCRE uses only the numbers when matching. For this reason, an error is given at compile time if different names -are given to subpatterns with the same number. However, you can give the same -name to subpatterns with the same number, even when PCRE_DUPNAMES is not set. +are given to subpatterns with the same number. However, you can always give the +same name to subpatterns with the same number, even when PCRE_DUPNAMES is not +set. </P> <br><a name="SEC16" href="#TOC1">REPETITION</a><br> <P> @@ -2252,12 +2342,7 @@ Checking for a used subpattern by name <P> Perl uses the syntax (?(<name>)...) or (?('name')...) to test for a used subpattern by name. For compatibility with earlier versions of PCRE, which had -this facility before Perl, the syntax (?(name)...) is also recognized. However, -there is a possible ambiguity with this syntax, because subpattern names may -consist entirely of digits. PCRE looks first for a named subpattern; if it -cannot find one and the name consists entirely of digits, PCRE looks for a -subpattern of that number, which must be greater than zero. Using subpattern -names that consist entirely of digits is not recommended. +this facility before Perl, the syntax (?(name)...) is also recognized. </P> <P> Rewriting the above example to use a named subpattern gives this: @@ -2674,8 +2759,14 @@ During matching, when PCRE reaches a callout point, the external function is called. It is provided with the number of the callout, the position in the pattern, and, optionally, one item of data originally supplied by the caller of the matching function. The callout function may cause matching to proceed, to -backtrack, or to fail altogether. A complete description of the interface to -the callout function is given in the +backtrack, or to fail altogether. +</P> +<P> +By default, PCRE implements a number of optimizations at compile time and +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, and a complete description of the +interface to the callout function, are given in the <a href="pcrecallout.html"><b>pcrecallout</b></a> documentation. <a name="backtrackcontrol"></a></P> @@ -3026,7 +3117,7 @@ example: <pre> ...(*COMMIT)(*PRUNE)... </pre> -If there is a matching failure to the right, backtracking onto (*PRUNE) cases +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 a backtrack onto (*COMMIT). <a name="btrepeat"></a></P> @@ -3109,7 +3200,7 @@ Cambridge CB2 3QH, England. </P> <br><a name="SEC29" href="#TOC1">REVISION</a><br> <P> -Last updated: 26 April 2013 +Last updated: 12 November 2013 <br> Copyright © 1997-2013 University of Cambridge. <br> diff --git a/doc/html/pcreprecompile.html b/doc/html/pcreprecompile.html index beb9e24..decb1d6 100644 --- a/doc/html/pcreprecompile.html +++ b/doc/html/pcreprecompile.html @@ -102,8 +102,8 @@ study data. <br><a name="SEC3" href="#TOC1">RE-USING A PRECOMPILED PATTERN</a><br> <P> Re-using a precompiled pattern is straightforward. Having reloaded it into main -memory, called <b>pcre[16|32]_pattern_to_host_byte_order()</b> if necessary, -you pass its pointer to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b> in +memory, called <b>pcre[16|32]_pattern_to_host_byte_order()</b> if necessary, you +pass its pointer to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b> in the usual way. </P> <P> @@ -119,6 +119,11 @@ in the documentation. </P> <P> +<b>Warning:</b> The tables that <b>pcre_exec()</b> and <b>pcre_dfa_exec()</b> use +must be the same as those that were used when the pattern was compiled. If this +is not the case, the behaviour is undefined. +</P> +<P> If you did not provide custom character tables when the pattern was compiled, the pointer in the compiled pattern is NULL, which causes the matching functions to use PCRE's internal tables. Thus, you do not need to take any @@ -126,9 +131,9 @@ special action at run time in this case. </P> <P> If you saved study data with the compiled pattern, you need to create your own -<b>pcre[16|32]_extra</b> data block and set the <i>study_data</i> field to point to the -reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in the -<i>flags</i> field to indicate that study data is present. Then pass the +<b>pcre[16|32]_extra</b> data block and set the <i>study_data</i> field to point +to the reloaded study data. You must also set the PCRE_EXTRA_STUDY_DATA bit in +the <i>flags</i> field to indicate that study data is present. Then pass the <b>pcre[16|32]_extra</b> block to the matching function in the usual way. If the pattern was studied for just-in-time optimization, that data cannot be saved, and so is lost by a save/restore cycle. @@ -149,9 +154,9 @@ Cambridge CB2 3QH, England. </P> <br><a name="SEC6" href="#TOC1">REVISION</a><br> <P> -Last updated: 24 June 2012 +Last updated: 12 November 2013 <br> -Copyright © 1997-2012 University of Cambridge. +Copyright © 1997-2013 University of Cambridge. <br> <p> Return to the <a href="index.html">PCRE index page</a>. diff --git a/doc/html/pcresyntax.html b/doc/html/pcresyntax.html index b32e8b1..0764a33 100644 --- a/doc/html/pcresyntax.html +++ b/doc/html/pcresyntax.html @@ -65,10 +65,14 @@ documentation. This document contains a quick-reference summary of the syntax. \n newline (hex 0A) \r carriage return (hex 0D) \t tab (hex 09) + \0dd character with octal code 0dd \ddd character with octal code ddd, or backreference + \o{ddd..} character with octal code ddd.. \xhh character with hex code hh \x{hhh..} character with hex code hhh.. -</PRE> +</pre> +Note that \0dd is always an octal code, and that \8 and \9 are the literal +characters "8" and "9". </P> <br><a name="SEC4" href="#TOC1">CHARACTER TYPES</a><br> <P> @@ -92,9 +96,11 @@ documentation. This document contains a quick-reference summary of the syntax. \W a "non-word" character \X a Unicode extended grapheme cluster </pre> -In PCRE, by default, \d, \D, \s, \S, \w, and \W recognize only ASCII -characters, even in a UTF mode. However, this can be changed by setting the -PCRE_UCP option. +By default, \d, \s, and \w match only ASCII characters, even in UTF-8 mode +or in the 16- bit and 32-bit libraries. However, if locale-specific matching is +happening, \s and \w may also match characters with code points in the range +128-255. If the PCRE_UCP option is set, the behaviour of these escape sequences +is changed to use Unicode properties and they match many more characters. </P> <br><a name="SEC5" href="#TOC1">GENERAL CATEGORY PROPERTIES FOR \p and \P</a><br> <P> @@ -150,11 +156,13 @@ PCRE_UCP option. <pre> Xan Alphanumeric: union of properties L and N Xps POSIX space: property Z or tab, NL, VT, FF, CR - Xsp Perl space: property Z or tab, NL, FF, CR + Xsp Perl space: property Z or tab, NL, VT, FF, CR Xuc Univerally-named character: one that can be represented by a Universal Character Name Xwd Perl word: property Xan or underscore -</PRE> +</pre> +Perl and POSIX space are now the same. Perl added VT to its space character set +at release 5.18 and PCRE changed at release 8.34. </P> <br><a name="SEC7" href="#TOC1">SCRIPT NAMES FOR \p AND \P</a><br> <P> @@ -385,7 +393,9 @@ newline-setting options with similar syntax: (*UTF32) set UTF-32 mode: 32-bit library (PCRE_UTF32) (*UTF) set appropriate UTF mode for the library in use (*UCP) set PCRE_UCP (use Unicode properties for \d etc) -</PRE> +</pre> +Note that LIMIT_MATCH and LIMIT_RECURSION can only reduce the value of the +limits set by the caller of pcre_exec(), not increase them. </P> <br><a name="SEC17" href="#TOC1">LOOKAHEAD AND LOOKBEHIND ASSERTIONS</a><br> <P> @@ -516,7 +526,7 @@ Cambridge CB2 3QH, England. </P> <br><a name="SEC27" href="#TOC1">REVISION</a><br> <P> -Last updated: 26 April 2013 +Last updated: 12 November 2013 <br> Copyright © 1997-2013 University of Cambridge. <br> diff --git a/doc/html/pcretest.html b/doc/html/pcretest.html index 17d1ade..4ed1dfd 100644 --- a/doc/html/pcretest.html +++ b/doc/html/pcretest.html @@ -187,6 +187,11 @@ equivalent to adding <b>/M</b> to each regular expression. The size is given in bytes for both libraries. </P> <P> +<b>-O</b> +Behave as if each pattern has the <b>/O</b> modifier, that is disable +auto-possessification for all patterns. +</P> +<P> <b>-o</b> <i>osize</i> Set the number of elements in the output vector that is used when calling <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b> to be <i>osize</i>. The @@ -256,19 +261,24 @@ should never be studied (see the <b>/S</b> pattern modifier below). </P> <P> <b>-t</b> -Run each compile, study, and match many times with a timer, and output -resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with -<b>-t</b>, because you will then get the size output a zillion times, and the -timing will be distorted. You can control the number of iterations that are -used for timing by following <b>-t</b> with a number (as a separate item on the -command line). For example, "-t 1000" would iterate 1000 times. The default is -to iterate 500000 times. +Run each compile, study, and match many times with a timer, and output the +resulting times per compile, study, or match (in milliseconds). Do not set +<b>-m</b> with <b>-t</b>, because you will then get the size output a zillion +times, and the timing will be distorted. You can control the number of +iterations that are used for timing by following <b>-t</b> with a number (as a +separate item on the command line). For example, "-t 1000" iterates 1000 times. +The default is to iterate 500000 times. </P> <P> <b>-tm</b> This is like <b>-t</b> except that it times only the matching phase, not the compile or study phases. </P> +<P> +<b>-T</b> <b>-TM</b> +These behave like <b>-t</b> and <b>-tm</b>, but in addition, at the end of a run, +the total times for all compiles, studies, and matches are output. +</P> <br><a name="SEC5" href="#TOC1">DESCRIPTION</a><br> <P> If <b>pcretest</b> is given two filename arguments, it reads from the first and @@ -287,7 +297,7 @@ option states whether or not <b>readline()</b> will be used. <P> The program handles any number of sets of input on a single input file. Each set starts with a regular expression, and continues with any number of data -lines to be matched against the pattern. +lines to be matched against that pattern. </P> <P> Each data line is matched separately and independently. If you want to do @@ -361,6 +371,7 @@ sections. <b>/M</b> show compiled memory size <b>/m</b> set PCRE_MULTILINE <b>/N</b> set PCRE_NO_AUTO_CAPTURE + <b>/O</b> set PCRE_NO_AUTO_POSSESS <b>/P</b> use the POSIX wrapper <b>/S</b> study the pattern after compilation <b>/s</b> set PCRE_DOTALL @@ -419,6 +430,7 @@ options that do not correspond to anything in Perl: <b>/f</b> PCRE_FIRSTLINE <b>/J</b> PCRE_DUPNAMES <b>/N</b> PCRE_NO_AUTO_CAPTURE + <b>/O</b> PCRE_NO_AUTO_POSSESS <b>/U</b> PCRE_UNGREEDY <b>/W</b> PCRE_UCP <b>/X</b> PCRE_EXTRA @@ -562,8 +574,8 @@ matched. There are a number of qualifying characters that may follow <b>/S</b>. They may appear in any order. </P> <P> -If <b>S</b> is followed by an exclamation mark, <b>pcre[16|32]_study()</b> is called -with the PCRE_STUDY_EXTRA_NEEDED option, causing it always to return a +If <b>/S</b> is followed by an exclamation mark, <b>pcre[16|32]_study()</b> is +called with the PCRE_STUDY_EXTRA_NEEDED option, causing it always to return a <b>pcre_extra</b> block, even when studying discovers no useful information. </P> <P> @@ -642,6 +654,37 @@ function: The <b>/+</b> modifier works as described above. All other modifiers are ignored. </P> +<br><b> +Locking out certain modifiers +</b><br> +<P> +PCRE can be compiled with or without support for certain features such as +UTF-8/16/32 or Unicode properties. Accordingly, the standard tests are split up +into a number of different files that are selected for running depending on +which features are available. When updating the tests, it is all too easy to +put a new test into the wrong file by mistake; for example, to put a test that +requires UTF support into a file that is used when it is not available. To help +detect such mistakes as early as possible, there is a facility for locking out +specific modifiers. If an input line for <b>pcretest</b> starts with the string +"< forbid " the following sequence of characters is taken as a list of +forbidden modifiers. For example, in the test files that must not use UTF or +Unicode property support, this line appears: +<pre> + < forbid 8W +</pre> +This locks out the /8 and /W modifiers. An immediate error is given if they are +subsequently encountered. If the character string contains < but not >, all the +multi-character modifiers that begin with < are locked out. Otherwise, such +modifiers must be explicitly listed, for example: +<pre> + < forbid <JS><cr> +</pre> +There must be a single space between < and "forbid" for this feature to be +recognised. If there is not, the line is interpreted either as a request to +re-load a pre-compiled pattern (see "SAVING AND RELOADING COMPILED PATTERNS" +below) or, if there is a another < character, as a pattern that uses < as its +delimiter. +</P> <br><a name="SEC7" href="#TOC1">DATA LINES</a><br> <P> Before each data line is passed to <b>pcre[16|32]_exec()</b>, leading and trailing @@ -662,6 +705,7 @@ recognized: \v vertical tab (\x0b) \nnn octal character (up to 3 octal digits); always a byte unless > 255 in UTF-8 or 16-bit or 32-bit mode + \o{dd...} octal character (any number of octal digits} \xhh hexadecimal byte (up to 2 hex digits) \x{hh...} hexadecimal character (any number of hex digits) \A pass the PCRE_ANCHORED option to <b>pcre[16|32]_exec()</b> or <b>pcre[16|32]_dfa_exec()</b> @@ -1031,10 +1075,9 @@ writing the file, <b>pcretest</b> expects to read a new pattern. </P> <P> A saved pattern can be reloaded into <b>pcretest</b> by specifying < and a file -name instead of a pattern. The name of the file must not contain a < character, -as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by < -characters. -For example: +name instead of a pattern. There must be no space between < and the file name, +which must not contain a < character, as otherwise <b>pcretest</b> will +interpret the line as a pattern delimited by < characters. For example: <pre> re> </some/file Compiled pattern loaded from /some/file @@ -1091,7 +1134,7 @@ Cambridge CB2 3QH, England. </P> <br><a name="SEC17" href="#TOC1">REVISION</a><br> <P> -Last updated: 26 April 2013 +Last updated: 12 November 2013 <br> Copyright © 1997-2013 University of Cambridge. <br> diff --git a/doc/pcre.txt b/doc/pcre.txt index 7e990d0..ba69f54 100644 --- a/doc/pcre.txt +++ b/doc/pcre.txt @@ -53,7 +53,7 @@ INTRODUCTION 5.12, including support for UTF-8/16/32 encoded strings and Unicode general category properties. However, UTF-8/16/32 and Unicode support has to be explicitly enabled; it is not the default. The Unicode tables - correspond to Unicode release 6.2.0. + correspond to Unicode release 6.3.0. In addition to the Perl-compatible matching function, PCRE contains an alternative function that matches the same compiled patterns in a dif- @@ -180,8 +180,8 @@ REVISION Last updated: 13 May 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRE(3) Library Functions Manual PCRE(3) @@ -512,8 +512,8 @@ REVISION Last updated: 12 May 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRE(3) Library Functions Manual PCRE(3) @@ -840,8 +840,8 @@ REVISION Last updated: 12 May 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREBUILD(3) Library Functions Manual PCREBUILD(3) @@ -1343,8 +1343,8 @@ REVISION Last updated: 12 May 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREMATCHING(3) Library Functions Manual PCREMATCHING(3) @@ -1457,72 +1457,81 @@ THE ALTERNATIVE MATCHING ALGORITHM at the fifth character of the subject. The algorithm does not automati- cally move on to find matches that start at later positions. + PCRE's "auto-possessification" optimization usually applies to charac- + ter repeats at the end of a pattern (as well as internally). For exam- + ple, the pattern "a\d+" is compiled as if it were "a\d++" because there + is no point even considering the possibility of backtracking into the + repeated digits. For DFA matching, this means that only one possible + match is found. If you really do want multiple matches in such cases, + either use an ungreedy repeat ("a\d+?") or set the PCRE_NO_AUTO_POSSESS + option when compiling. + There are a number of features of PCRE regular expressions that are not supported by the alternative matching algorithm. They are as follows: - 1. Because the algorithm finds all possible matches, the greedy or - ungreedy nature of repetition quantifiers is not relevant. Greedy and + 1. Because the algorithm finds all possible matches, the greedy or + ungreedy nature of repetition quantifiers is not relevant. Greedy and ungreedy quantifiers are treated in exactly the same way. However, pos- - sessive quantifiers can make a difference when what follows could also + sessive quantifiers can make a difference when what follows could also match what is quantified, for example in a pattern like this: ^a++\w! - This pattern matches "aaab!" but not "aaa!", which would be matched by - a non-possessive quantifier. Similarly, if an atomic group is present, - it is matched as if it were a standalone pattern at the current point, - and the longest match is then "locked in" for the rest of the overall + This pattern matches "aaab!" but not "aaa!", which would be matched by + a non-possessive quantifier. Similarly, if an atomic group is present, + it is matched as if it were a standalone pattern at the current point, + and the longest match is then "locked in" for the rest of the overall pattern. 2. When dealing with multiple paths through the tree simultaneously, it - is not straightforward to keep track of captured substrings for the - different matching possibilities, and PCRE's implementation of this + is not straightforward to keep track of captured substrings for the + different matching possibilities, and PCRE's implementation of this algorithm does not attempt to do this. This means that no captured sub- strings are available. - 3. Because no substrings are captured, back references within the pat- + 3. Because no substrings are captured, back references within the pat- tern are not supported, and cause errors if encountered. - 4. For the same reason, conditional expressions that use a backrefer- - ence as the condition or test for a specific group recursion are not + 4. For the same reason, conditional expressions that use a backrefer- + ence as the condition or test for a specific group recursion are not supported. - 5. Because many paths through the tree may be active, the \K escape + 5. Because many paths through the tree may be active, the \K escape sequence, which resets the start of the match when encountered (but may - be on some paths and not on others), is not supported. It causes an + be on some paths and not on others), is not supported. It causes an error if encountered. - 6. Callouts are supported, but the value of the capture_top field is + 6. Callouts are supported, but the value of the capture_top field is always 1, and the value of the capture_last field is always -1. - 7. The \C escape sequence, which (in the standard algorithm) always - matches a single data unit, even in UTF-8, UTF-16 or UTF-32 modes, is - not supported in these modes, because the alternative algorithm moves + 7. The \C escape sequence, which (in the standard algorithm) always + matches a single data unit, even in UTF-8, UTF-16 or UTF-32 modes, is + not supported in these modes, because the alternative algorithm moves through the subject string one character (not data unit) at a time, for all active paths through the tree. - 8. Except for (*FAIL), the backtracking control verbs such as (*PRUNE) - are not supported. (*FAIL) is supported, and behaves like a failing + 8. Except for (*FAIL), the backtracking control verbs such as (*PRUNE) + are not supported. (*FAIL) is supported, and behaves like a failing negative assertion. ADVANTAGES OF THE ALTERNATIVE ALGORITHM - Using the alternative matching algorithm provides the following advan- + Using the alternative matching algorithm provides the following advan- tages: 1. All possible matches (at a single point in the subject) are automat- - ically found, and in particular, the longest match is found. To find + ically found, and in particular, the longest match is found. To find more than one match using the standard algorithm, you have to do kludgy things with callouts. - 2. Because the alternative algorithm scans the subject string just + 2. Because the alternative algorithm scans the subject string just once, and never needs to backtrack (except for lookbehinds), it is pos- - sible to pass very long subject strings to the matching function in + sible to pass very long subject strings to the matching function in several pieces, checking for partial matching each time. Although it is - possible to do multi-segment matching using the standard algorithm by - retaining partially matched substrings, it is more complicated. The - pcrepartial documentation gives details of partial matching and dis- + possible to do multi-segment matching using the standard algorithm by + retaining partially matched substrings, it is more complicated. The + pcrepartial documentation gives details of partial matching and dis- cusses multi-segment matching. @@ -1530,8 +1539,8 @@ DISADVANTAGES OF THE ALTERNATIVE ALGORITHM The alternative algorithm suffers from a number of disadvantages: - 1. It is substantially slower than the standard algorithm. This is - partly because it has to search for all possible matches, but is also + 1. It is substantially slower than the standard algorithm. This is + partly because it has to search for all possible matches, but is also because it is less susceptible to optimization. 2. Capturing parentheses and back references are not supported. @@ -1549,11 +1558,11 @@ AUTHOR REVISION - Last updated: 08 January 2012 + Last updated: 12 November 2013 Copyright (c) 1997-2012 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREAPI(3) Library Functions Manual PCREAPI(3) @@ -1957,27 +1966,34 @@ CHECKING BUILD-TIME OPTIONS POSIX interface uses malloc() for output vectors. Further details are given in the pcreposix documentation. + PCRE_CONFIG_PARENS_LIMIT + + The output is a long integer that gives the maximum depth of nesting 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 spec- + ified when PCRE is built; the default is 250. + PCRE_CONFIG_MATCH_LIMIT - The output is a long integer that gives the default limit for the num- - ber of internal matching function calls in a pcre_exec() execution. + The output is a long integer that gives the default limit for the num- + ber of internal matching function calls in a pcre_exec() execution. Further details are given with pcre_exec() below. PCRE_CONFIG_MATCH_LIMIT_RECURSION The output is a long integer that gives the default limit for the depth - of recursion when calling the internal matching function in a - pcre_exec() execution. Further details are given with pcre_exec() + of recursion when calling the internal matching function in a + pcre_exec() execution. Further details are given with pcre_exec() below. PCRE_CONFIG_STACKRECURSE - The output is an integer that is set to one if internal recursion when + The output is an integer that is set to one if internal recursion when running pcre_exec() is implemented by recursive function calls that use - the stack to remember their state. This is the usual way that PCRE is + the stack to remember their state. This is the usual way that PCRE is compiled. The output is zero if PCRE was compiled to use blocks of data - on the heap instead of recursive function calls. In this case, - pcre_stack_malloc and pcre_stack_free are called to manage memory + on the heap instead of recursive function calls. In this case, + pcre_stack_malloc and pcre_stack_free are called to manage memory blocks on the heap, thus avoiding the use of the stack. @@ -1994,67 +2010,67 @@ COMPILING A PATTERN Either of the functions pcre_compile() or pcre_compile2() can be called to compile a pattern into an internal form. The only difference between - the two interfaces is that pcre_compile2() has an additional argument, - errorcodeptr, via which a numerical error code can be returned. To - avoid too much repetition, we refer just to pcre_compile() below, but + the two interfaces is that pcre_compile2() has an additional argument, + errorcodeptr, via which a numerical error code can be returned. To + avoid too much repetition, we refer just to pcre_compile() below, but the information applies equally to pcre_compile2(). The pattern is a C string terminated by a binary zero, and is passed in - the pattern argument. A pointer to a single block of memory that is - obtained via pcre_malloc is returned. This contains the compiled code + the pattern argument. A pointer to a single block of memory that is + obtained via pcre_malloc is returned. This contains the compiled code and related data. The pcre type is defined for the returned block; this is a typedef for a structure whose contents are not externally defined. It is up to the caller to free the memory (via pcre_free) when it is no longer required. - Although the compiled code of a PCRE regex is relocatable, that is, it + Although the compiled code of a PCRE regex is relocatable, that is, it does not depend on memory location, the complete pcre data block is not - fully relocatable, because it may contain a copy of the tableptr argu- + fully relocatable, because it may contain a copy of the tableptr argu- ment, which is an address (see below). 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 - pcrepattern documentation). For those options that can be different in - different parts of the pattern, the contents of the options argument + 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 + pcrepattern documentation). For those options that can be different in + different parts of the pattern, the contents of the options argument specifies their settings at the start of compilation and execution. The - PCRE_ANCHORED, PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK, and - PCRE_NO_START_OPTIMIZE options can be set at the time of matching as + PCRE_ANCHORED, PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK, and + PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at compile time. If errptr is NULL, pcre_compile() returns NULL immediately. Otherwise, - if compilation of a pattern fails, pcre_compile() returns NULL, and + if compilation of a pattern fails, pcre_compile() returns NULL, and sets the variable pointed to by errptr to point to a textual error mes- sage. This is a static string that is part of the library. You must not - try to free it. Normally, the offset from the start of the pattern to + try to free it. Normally, the offset from the start of the pattern to the data unit that was being processed when the error was discovered is - placed in the variable pointed to by erroffset, which must not be NULL - (if it is, an immediate error is given). However, for an invalid UTF-8 - or UTF-16 string, the offset is that of the first data unit of the + placed in the variable pointed to by erroffset, which must not be NULL + (if it is, an immediate error is given). However, for an invalid UTF-8 + or UTF-16 string, the offset is that of the first data 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 data 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 data units, not characters, even in a UTF mode. It may sometimes point into the middle of a UTF-8 or UTF-16 char- acter. - If pcre_compile2() is used instead of pcre_compile(), and the error- - codeptr argument is not NULL, a non-zero error code number is returned - via this argument in the event of an error. This is in addition to the + If pcre_compile2() is used instead of pcre_compile(), and the error- + codeptr argument is not NULL, a non-zero error code number is returned + via this argument in the event of an error. This is in addition to the textual error message. Error codes and messages are listed below. - If the final argument, tableptr, is NULL, PCRE uses a default set of - character tables that are built when PCRE is compiled, using the - default C locale. Otherwise, tableptr must be an address that is the - result of a call to pcre_maketables(). This value is stored with the - compiled pattern, and used again by pcre_exec(), unless another table - pointer is passed to it. For more discussion, see the section on locale - support below. + If the final argument, tableptr, is NULL, PCRE uses a default set of + character tables that are built when PCRE is compiled, using the + default C locale. Otherwise, tableptr must be an address that is the + result of a call to pcre_maketables(). This value is stored with the + compiled pattern, and used again by pcre_exec() and pcre_dfa_exec() + when the pattern is matched. For more discussion, see the section on + locale support below. - This code fragment shows a typical straightforward call to pcre_com- + This code fragment shows a typical straightforward call to pcre_com- pile(): pcre *re; @@ -2067,171 +2083,181 @@ COMPILING A PATTERN &erroffset, /* for error offset */ NULL); /* use default character tables */ - The following names for option bits are defined in the pcre.h header + The following names for option bits are defined in the pcre.h header file: PCRE_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. PCRE_AUTO_CALLOUT If this bit is set, pcre_compile() automatically inserts callout items, - all with number 255, before each pattern item. For discussion of the + all with number 255, before each pattern item. For discussion of the callout facility, see the pcrecallout documentation. PCRE_BSR_ANYCRLF PCRE_BSR_UNICODE These options (which are mutually exclusive) control what the \R escape - sequence matches. The choice is either to match only CR, LF, or CRLF, + sequence matches. The choice is either to match only CR, LF, or CRLF, or to match any Unicode newline sequence. The default is specified when PCRE is built. It can be overridden from within the pattern, or by set- ting an option when a compiled pattern is matched. PCRE_CASELESS - If this bit is set, letters in the pattern match both upper and lower - case letters. It is equivalent to Perl's /i option, and it can be - changed within a pattern by a (?i) option setting. In UTF-8 mode, PCRE - always understands the concept of case for characters whose values are - less than 128, so caseless matching is always possible. For characters - with higher values, the concept of case is supported if PCRE is com- - piled with Unicode property support, but not otherwise. If you want to - use caseless matching for characters 128 and above, you must ensure - that PCRE is compiled with Unicode property support as well as with + If this bit is set, letters in the pattern match both upper and lower + case letters. It is equivalent to Perl's /i option, and it can be + changed within a pattern by a (?i) option setting. In UTF-8 mode, PCRE + always understands the concept of case for characters whose values are + less than 128, so caseless matching is always possible. For characters + with higher values, the concept of case is supported if PCRE is com- + piled with Unicode property support, but not otherwise. If you want to + use caseless matching for characters 128 and above, you must ensure + that PCRE is compiled with Unicode property support as well as with UTF-8 support. PCRE_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 PCRE_DOLLAR_ENDONLY option is ignored - if PCRE_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 PCRE_DOLLAR_ENDONLY option is ignored + if PCRE_MULTILINE is set. There is no equivalent to this option in Perl, and no way to set it within a pattern. PCRE_DOTALL - If this bit is set, a dot metacharacter in the pattern matches a char- + If this bit is set, a dot metacharacter in the pattern matches a char- acter of any value, 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 is + only ever matches one character, even if newlines are coded as CRLF. + Without this option, a dot does not match when the current position 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 negative class + be changed within a pattern by a (?s) option setting. A negative class such as [^a] always matches newline characters, independent of the set- ting of this option. PCRE_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 pcrepattern documentation. PCRE_EXTENDED - If this bit is set, white space data characters in the pattern are - totally ignored except when escaped or inside a character class. White - space does not include the VT character (code 11). In addition, charac- - ters between an unescaped # outside a character class and the next new- - line, inclusive, are also ignored. This is equivalent to Perl's /x - option, and it can be changed within a pattern by a (?x) option set- - ting. - - Which characters are interpreted as newlines is controlled by the - options passed to pcre_compile() or by a special sequence at the start - of the pattern, as described in the section entitled "Newline conven- + 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 a numerical + quantifier such as {1,3}. However, ignorable white space is permitted + between an item and a following quantifier and between a quantifier and + a following + that indicates possessiveness. + + White space did not used to include the VT character (code 11), because + Perl did not treat this character as white space. However, Perl changed + at release 5.18, so PCRE followed at release 8.34, and VT is now + treated as white space. + + PCRE_EXTENDED also causes characters between an unescaped # outside a + character class and the next newline, inclusive, to be ignored. + PCRE_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 is controlled by the + options passed to pcre_compile() or by a special sequence at the start + of the pattern, as described in the section entitled "Newline conven- tions" in the pcrepattern documentation. Note that the end of this type - of comment is a literal newline sequence in the pattern; escape + of comment is a literal newline sequence in the pattern; escape sequences that happen to represent a newline do not count. - This option makes it possible to include comments inside complicated - patterns. Note, however, that this applies only to data characters. - White space characters may never appear within special character + This option makes it possible to include comments inside complicated + patterns. Note, however, that this applies only to data characters. + White space characters may never appear within special character sequences in a pattern, for example within the sequence (?( that intro- duces a conditional subpattern. PCRE_EXTRA - This option was invented in order to turn on additional functionality - of PCRE that is incompatible with Perl, but it is currently of very - little use. When set, any backslash in a pattern that is followed by a - letter that has no special meaning causes an error, thus reserving - these combinations for future expansion. By default, as in Perl, a - backslash followed by a letter with no special meaning is treated as a + This option was invented in order to turn on additional functionality + of PCRE that is incompatible with Perl, but it is currently of very + little use. When set, any backslash in a pattern that is followed by a + letter that has no special meaning causes an error, thus reserving + these combinations for future expansion. By default, as in Perl, a + backslash followed by a letter with no special meaning is treated as a literal. (Perl can, however, be persuaded to give an error for this, by - running it with the -w option.) There are at present no other features - controlled by this option. It can also be set by a (?X) option setting + running it with the -w option.) There are at present no other features + controlled by this option. It can also be set by a (?X) option setting within a pattern. PCRE_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 + 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. PCRE_JAVASCRIPT_COMPAT If this option is set, PCRE's behaviour is changed in some ways so that - it is compatible with JavaScript rather than Perl. The changes are as + it is compatible with JavaScript rather than Perl. The changes are as follows: - (1) A lone closing square bracket in a pattern causes a compile-time - error, because this is illegal in JavaScript (by default it is treated + (1) A lone closing square bracket in a pattern causes a compile-time + error, because this is illegal in JavaScript (by default it is treated as a data character). Thus, the pattern AB]CD becomes illegal when this option is set. - (2) At run time, a back reference to an unset subpattern group matches - an empty string (by default this causes the current matching alterna- - tive 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 + (2) At run time, a back reference to an unset subpattern group matches + an empty string (by default this causes the current matching alterna- + tive 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. (3) \U matches an upper case "U" character; by default \U causes a com- pile time error (Perl uses \U to upper case subsequent characters). (4) \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). - (5) \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 + (5) \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). PCRE_MULTILINE - By default, for the purposes of matching "start of line" and "end of + By default, for the purposes of matching "start of line" and "end of line", PCRE treats the subject string as consisting of a single line of - characters, even if it actually contains newlines. The "start of line" + 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 ($) matches only at the end of the string, or - before a terminating newline (except when PCRE_DOLLAR_ENDONLY is set). - Note, however, that unless PCRE_DOTALL is set, the "any character" - metacharacter (.) does not match at a newline. This behaviour (for ^, + of line" metacharacter ($) matches only at the end of the string, or + before a terminating newline (except when PCRE_DOLLAR_ENDONLY is set). + Note, however, that unless PCRE_DOTALL is set, the "any character" + metacharacter (.) does not match at a newline. This behaviour (for ^, $, and dot) is the same as Perl. - When PCRE_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 PCRE_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. If there are no new- - lines in a subject string, or no occurrences of ^ or $ in a pattern, + lines in a subject string, or no occurrences of ^ or $ in a pattern, setting PCRE_MULTILINE has no effect. PCRE_NEVER_UTF This option locks out interpretation of the pattern as UTF-8 (or UTF-16 - or UTF-32 in the 16-bit and 32-bit libraries). In particular, it pre- - vents the creator of the pattern from switching to UTF interpretation + or UTF-32 in the 16-bit and 32-bit libraries). In particular, it pre- + vents the creator of the pattern from switching to UTF interpretation by starting the pattern with (*UTF). This may be useful in applications that process patterns from external sources. The combination of PCRE_UTF8 and PCRE_NEVER_UTF also causes an error. @@ -2242,41 +2268,41 @@ COMPILING A PATTERN PCRE_NEWLINE_ANYCRLF PCRE_NEWLINE_ANY - These options override the default newline definition that was chosen - when PCRE was built. Setting the first or the second specifies that a - newline is indicated by a single character (CR or LF, respectively). - Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by the - two-character CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies + These options override the default newline definition that was chosen + when PCRE was built. Setting the first or the second specifies that a + newline is indicated by a single character (CR or LF, respectively). + Setting PCRE_NEWLINE_CRLF specifies that a newline is indicated by the + two-character CRLF sequence. Setting PCRE_NEWLINE_ANYCRLF specifies that any of the three preceding sequences should be recognized. Setting - PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should be + PCRE_NEWLINE_ANY specifies that any Unicode newline sequence should be recognized. - In an ASCII/Unicode environment, the Unicode newline sequences are the - three just mentioned, plus the single characters VT (vertical tab, + In an ASCII/Unicode environment, the Unicode newline sequences are the + three just mentioned, plus the single characters VT (vertical tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line sep- - arator, U+2028), and PS (paragraph separator, U+2029). For the 8-bit + arator, U+2028), and PS (paragraph separator, U+2029). For the 8-bit library, the last two are recognized only in UTF-8 mode. - When PCRE is compiled to run in an EBCDIC (mainframe) environment, the + When PCRE is compiled to run in an EBCDIC (mainframe) environment, the code for CR is 0x0d, the same as ASCII. However, the character code for - LF is normally 0x15, though in some EBCDIC environments 0x25 is used. - Whichever of these is not LF is made to correspond to Unicode's NEL - character. EBCDIC codes are all less than 256. For more details, see + LF is normally 0x15, though in some EBCDIC environments 0x25 is used. + Whichever of these is not LF is made to correspond to Unicode's NEL + character. EBCDIC codes are all less than 256. For more details, see the pcrebuild documentation. - The newline setting in the options word uses three bits that are + The newline setting in the options word uses three bits that are treated as a number, giving eight possibilities. Currently only six are - used (default plus the five values above). This means that if you set - more than one newline option, the combination may or may not be sensi- + used (default plus the five values above). This means that if you set + more than one newline option, the combination may or may not be sensi- ble. For example, PCRE_NEWLINE_CR with PCRE_NEWLINE_LF is equivalent to - PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers and + PCRE_NEWLINE_CRLF, but other combinations may yield unused numbers and cause an error. - The only time that a line break in a pattern is specially recognized - when compiling is when PCRE_EXTENDED is set. CR and LF are white space - characters, and so are ignored in this mode. Also, an unescaped # out- - side a character class indicates a comment that lasts until after the - next line break sequence. In other circumstances, line break sequences + The only time that a line break in a pattern is specially recognized + when compiling is when PCRE_EXTENDED is set. CR and LF are white space + characters, and so are ignored in this mode. Also, an unescaped # out- + side a character class indicates a comment that lasts until after the + next line break sequence. In other circumstances, line break sequences in patterns are treated as literal data. The newline option that is set at compile time becomes the default that @@ -2285,69 +2311,79 @@ COMPILING A PATTERN PCRE_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. + PCRE_NO_AUTO_POSSESS + + If this option is set, it disables "auto-possessification". This 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 of them 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 + provided for testing purposes. + PCRE_NO_START_OPTIMIZE - This is an option that acts at matching time; that is, it is really an - option for pcre_exec() or pcre_dfa_exec(). If it is set at compile - time, it is remembered with the compiled pattern and assumed at match- - ing time. This is necessary if you want to use JIT execution, because - the JIT compiler needs to know whether or not this option is set. For + This is an option that acts at matching time; that is, it is really an + option for pcre_exec() or pcre_dfa_exec(). If it is set at compile + time, it is remembered with the compiled pattern and assumed at match- + ing time. This is necessary if you want to use JIT execution, because + the JIT compiler needs to know whether or not this option is set. For details see the discussion of PCRE_NO_START_OPTIMIZE below. PCRE_UCP - This option changes the way PCRE 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 PCRE_UCP is set, Unicode properties - are used instead to classify characters. More details are given in the - section on generic character types in the pcrepattern page. If you set - PCRE_UCP, matching one of the items it affects takes much longer. The - option is available only if PCRE has been compiled with Unicode prop- + This option changes the way PCRE 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 PCRE_UCP is set, Unicode properties + are used instead to classify characters. More details are given in the + section on generic character types in the pcrepattern page. If you set + PCRE_UCP, matching one of the items it affects takes much longer. The + option is available only if PCRE has been compiled with Unicode prop- erty support. PCRE_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. PCRE_UTF8 - This option causes PCRE to regard both the pattern and the subject as + This option causes PCRE to regard both the pattern and the subject as strings of UTF-8 characters instead of single-byte strings. However, it - is available only when PCRE is built to include UTF support. If not, - the use of this option provokes an error. Details of how this option + is available only when PCRE is built to include UTF support. If not, + the use of this option provokes an error. Details of how this option changes the behaviour of PCRE are given in the pcreunicode page. PCRE_NO_UTF8_CHECK When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is - automatically checked. There is a discussion about the validity of - UTF-8 strings in the pcreunicode page. If an invalid UTF-8 sequence is - found, pcre_compile() returns an error. If you already know that your - pattern is valid, and you want to skip this check for performance rea- - sons, you can set the PCRE_NO_UTF8_CHECK option. When it is set, the + automatically checked. There is a discussion about the validity of + UTF-8 strings in the pcreunicode page. If an invalid UTF-8 sequence is + found, pcre_compile() returns an error. If you already know that your + pattern is valid, and you want to skip this check for performance rea- + sons, you can set the PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid UTF-8 string as a pattern is undefined. It - may cause your program to crash. Note that this option can also be - passed to pcre_exec() and pcre_dfa_exec(), to suppress the validity - checking of subject strings only. If the same string is being matched - many times, the option can be safely set for the second and subsequent + may cause your program to crash or loop. Note that this option can also + be passed to pcre_exec() and pcre_dfa_exec(), to suppress the validity + checking of subject strings only. If the same string is being matched + many times, the option can be safely set for the second and subsequent matchings to improve performance. COMPILATION ERROR CODES - The following table lists the error codes than may be returned by - pcre_compile2(), along with the error messages that may be returned by - both compiling functions. Note that error messages are always 8-bit - ASCII strings, even in 16-bit or 32-bit mode. As PCRE has developed, - some error codes have fallen out of use. To avoid confusion, they have + The following table lists the error codes than may be returned by + pcre_compile2(), along with the error messages that may be returned by + both compiling functions. Note that error messages are always 8-bit + ASCII strings, even in 16-bit or 32-bit mode. As PCRE has developed, + some error codes have fallen out of use. To avoid confusion, they have not been re-used. 0 no error @@ -2384,7 +2420,7 @@ COMPILATION ERROR CODES 31 POSIX collating elements are not supported 32 this version of PCRE is compiled without UTF support 33 [this code is not in use] - 34 character value in \x{...} sequence is too large + 34 character value in \x{} or \o{} is too large 35 invalid condition (?(0) 36 \C not allowed in lookbehind assertion 37 PCRE does not support \L, \l, \N{name}, \U, or \u @@ -2432,8 +2468,14 @@ COMPILATION ERROR CODES 75 name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN) 76 character value in \u.... sequence is too large 77 invalid UTF-32 string (specifically UTF-32) - - The numbers 32 and 10000 in errors 48 and 49 are defaults; different + 78 setting UTF is disabled by the application + 79 non-hex character in \x{} (closing brace missing?) + 80 non-octal character in \o{} (closing brace missing?) + 81 missing opening brace after \o + 82 parentheses are too deeply nested + 83 invalid range in character class + + The numbers 32 and 10000 in errors 48 and 49 are defaults; different values may be used if the limits were changed when PCRE was built. @@ -2442,64 +2484,64 @@ STUDYING A PATTERN pcre_extra *pcre_study(const pcre *code, int options, const char **errptr); - If a compiled pattern is going to be used several times, it is worth + If a compiled pattern is going to be used several times, it is worth spending more time analyzing it in order to speed up the time taken for - matching. The function pcre_study() takes a pointer to a compiled pat- + matching. The function pcre_study() takes a pointer to a compiled pat- tern as its first argument. If studying the pattern produces additional - information that will help speed up matching, pcre_study() returns a - pointer to a pcre_extra block, in which the study_data field points to + information that will help speed up matching, pcre_study() returns a + pointer to a pcre_extra block, in which the study_data field points to the results of the study. The returned value from pcre_study() can be passed directly to - pcre_exec() or pcre_dfa_exec(). However, a pcre_extra block also con- - tains other fields that can be set by the caller before the block is + pcre_exec() or pcre_dfa_exec(). However, a pcre_extra block also con- + tains other fields that can be set by the caller before the block is passed; these are described below in the section on matching a pattern. - If studying the pattern does not produce any useful information, - pcre_study() returns NULL by default. In that circumstance, if the + If studying the pattern does not produce any useful information, + pcre_study() returns NULL by default. In that circumstance, if the calling program wants to pass any of the other fields to pcre_exec() or - pcre_dfa_exec(), it must set up its own pcre_extra block. However, if - pcre_study() is called with the PCRE_STUDY_EXTRA_NEEDED option, it + pcre_dfa_exec(), it must set up its own pcre_extra block. However, if + pcre_study() is called with the PCRE_STUDY_EXTRA_NEEDED option, it returns a pcre_extra block even if studying did not find any additional - information. It may still return NULL, however, if an error occurs in + information. It may still return NULL, however, if an error occurs in pcre_study(). - The second argument of pcre_study() contains option bits. There are + The second argument of pcre_study() contains option bits. There are three further options in addition to PCRE_STUDY_EXTRA_NEEDED: PCRE_STUDY_JIT_COMPILE PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE - If any of these are set, and the just-in-time compiler is available, - the pattern is further compiled into machine code that executes much - faster than the pcre_exec() interpretive matching function. If the - just-in-time compiler is not available, these options are ignored. All + If any of these are set, and the just-in-time compiler is available, + the pattern is further compiled into machine code that executes much + faster than the pcre_exec() interpretive matching function. If the + just-in-time compiler is not available, these options are ignored. All undefined bits in the options argument must be zero. - 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 + 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 study time. Not all patterns can be optimized by the JIT compiler. For - those that cannot be handled, matching automatically falls back to the - pcre_exec() interpreter. For more details, see the pcrejit documenta- + those that cannot be handled, matching automatically falls back to the + pcre_exec() interpreter. For more details, see the pcrejit documenta- tion. - The third argument for pcre_study() is a pointer for an error message. - If studying succeeds (even if no data is returned), the variable it - points to is set to NULL. Otherwise it is set to point to a textual + The third argument for pcre_study() is a pointer for an error message. + If studying succeeds (even if no data is returned), the variable it + points to is set to NULL. Otherwise it is set to point to a textual error message. This is a static string that is part of the library. You - must not try to free it. You should test the error pointer for NULL + must not try to free it. You should test the error pointer for NULL after calling pcre_study(), to be sure that it has run successfully. - When you are finished with a pattern, you can free the memory used for + When you are finished with a pattern, you can free the memory used for the study data by calling pcre_free_study(). This function was added to - the API for release 8.20. For earlier versions, the memory could be - freed with pcre_free(), just like the pattern itself. This will still - work in cases where JIT optimization is not used, but it is advisable + the API for release 8.20. For earlier versions, the memory could be + freed with pcre_free(), just like the pattern itself. This will still + work in cases where JIT optimization is not used, but it is advisable to change to the new function when convenient. - This is a typical way in which pcre_study() is used (except that in a + This is a typical way in which pcre_study() is used (except that in a real application there should be tests for errors): int rc; @@ -2519,29 +2561,29 @@ STUDYING A PATTERN Studying a pattern does two things: first, a lower bound for the length of subject string that is needed to match the pattern is computed. This does not mean that there are any strings of that length that match, but - it does guarantee that no shorter strings match. The value is used to + it does guarantee that no shorter strings match. The value is used to avoid wasting time by trying to match strings that are shorter than the - lower bound. You can find out the value in a calling program via the + lower bound. You can find out the value in a calling program via the pcre_fullinfo() function. Studying a pattern is also useful for non-anchored patterns that do not - have a single fixed starting character. A bitmap of possible starting - bytes is created. This speeds up finding a position in the subject at + have a single fixed starting character. A bitmap of possible starting + bytes is created. This speeds up finding a position in the subject at which to start matching. (In 16-bit mode, the bitmap is used for 16-bit - values less than 256. In 32-bit mode, the bitmap is used for 32-bit + values less than 256. In 32-bit mode, the bitmap is used for 32-bit values less than 256.) - These two optimizations apply to both pcre_exec() and pcre_dfa_exec(), - and the information is also used by the JIT compiler. The optimiza- - tions can be disabled by setting the PCRE_NO_START_OPTIMIZE option. - You might want to do this if your pattern contains callouts or (*MARK) - and you want to make use of these facilities in cases where matching + These two optimizations apply to both pcre_exec() and pcre_dfa_exec(), + and the information is also used by the JIT compiler. The optimiza- + tions can be disabled by setting the PCRE_NO_START_OPTIMIZE option. + You might want to do this if your pattern contains callouts or (*MARK) + and you want to make use of these facilities in cases where matching fails. - PCRE_NO_START_OPTIMIZE can be specified at either compile time or exe- - cution time. However, if PCRE_NO_START_OPTIMIZE is passed to + PCRE_NO_START_OPTIMIZE can be specified at either compile time or exe- + cution time. However, if PCRE_NO_START_OPTIMIZE is passed to pcre_exec(), (that is, after any JIT compilation has happened) JIT exe- - cution is disabled. For JIT execution to work with PCRE_NO_START_OPTI- + cution is disabled. For JIT execution to work with PCRE_NO_START_OPTI- MIZE, the option must be set at compile time. There is a longer discussion of PCRE_NO_START_OPTIMIZE below. @@ -2549,17 +2591,20 @@ STUDYING A PATTERN LOCALE SUPPORT - PCRE handles caseless matching, and determines whether characters are - letters, digits, or whatever, by reference to a set of tables, indexed - by character value. When running in UTF-8 mode, this applies only to - characters with codes less than 128. By default, higher-valued codes - never match escapes such as \w or \d, but they can be tested with \p if - PCRE is built with Unicode character property support. Alternatively, - the PCRE_UCP option can be set at compile time; this causes \w and - friends to use Unicode property support instead of built-in tables. The - use of locales with Unicode is discouraged. If you are handling charac- - ters with codes greater than 128, you should either use UTF-8 and Uni- - code, or use locales, but not try to mix the two. + PCRE handles caseless matching, and determines whether characters are + letters, digits, or whatever, by reference to a set of tables, indexed + by character code point. When running in UTF-8 mode, or in the 16- or + 32-bit libraries, this applies only to characters with code points less + than 256. By default, higher-valued code points never match escapes + such as \w or \d. However, if PCRE is built with Unicode property sup- + port, all characters can be tested with \p and \P, or, alternatively, + the PCRE_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 + Unicode support, or use locales, but not try to mix the two. PCRE contains an internal set of tables that are used when the final argument of pcre_compile() is NULL. These are sufficient for many @@ -2575,10 +2620,10 @@ LOCALE SUPPORT External tables are built by calling the pcre_maketables() function, which has no arguments, in the relevant locale. The result can then be - passed to pcre_compile() or pcre_exec() as often as necessary. 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: + passed to pcre_compile() as often as necessary. 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 let- + ters), the following code could be used: setlocale(LC_CTYPE, "fr_FR"); tables = pcre_maketables(); @@ -2594,15 +2639,19 @@ LOCALE SUPPORT The pointer that is passed to pcre_compile() is saved with the compiled pattern, and the same tables are used via this pointer by pcre_study() - and normally also by pcre_exec(). Thus, by default, for any single pat- + and also by pcre_exec() and pcre_dfa_exec(). Thus, for any single pat- tern, compilation, studying and matching all happen in the same locale, - but different patterns can be compiled in different locales. + but different patterns can be processed in different locales. It is possible to pass a table pointer or NULL (indicating the use of - the internal tables) to pcre_exec(). Although not intended for this - purpose, this facility could be used to match a pattern in a different - locale from the one in which it was compiled. Passing table pointers at - run time is discussed below in the section on matching a pattern. + the internal tables) to pcre_exec() or pcre_dfa_exec() (see the discus- + sion below in the section on matching a pattern). This facility is pro- + vided for use with pre-compiled patterns that have been saved and + reloaded. Character tables are not saved with patterns, so if a non- + standard table was used at compile time, it must be provided again when + the reloaded pattern is matched. Attempting to use this facility to + match a pattern in a different locale from the one in which it was com- + piled is likely to lead to anomalous (usually incorrect) results. INFORMATION ABOUT A PATTERN @@ -2743,77 +2792,83 @@ INFORMATION ABOUT A PATTERN /^a\dz\d/ the returned value is -1. Since for the 32-bit library using the non-UTF-32 mode, this function - is unable to return the full 32-bit range of the character, this value - is deprecated; instead the PCRE_INFO_REQUIREDCHARFLAGS and + is unable to return the full 32-bit range of characters, this value is + deprecated; instead the PCRE_INFO_REQUIREDCHARFLAGS and PCRE_INFO_REQUIREDCHAR values should be used. + PCRE_INFO_MATCH_EMPTY + + Return 1 if the pattern can match an empty string, otherwise 0. The + fourth argument should point to an int variable. + PCRE_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 fourth - argument should point to an unsigned 32-bit integer. If no such value - has been set, the call to pcre_fullinfo() 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 fourth + argument should point to an unsigned 32-bit integer. If no such value + has been set, the call to pcre_fullinfo() returns the error PCRE_ERROR_UNSET. PCRE_INFO_MAXLOOKBEHIND - Return the number of characters (NB not data units) in the longest - lookbehind assertion in the pattern. This information is useful when - doing multi-segment matching using the partial matching facilities. + Return the number of characters (NB not data units) in the longest + lookbehind assertion in the pattern. 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 look- - behind. \A also registers a one-character lookbehind, though it does - not actually inspect the previous character. This is to ensure that at + behind. \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 processed. Otherwise, if there are no lookbehinds in the pattern, \A might match incorrectly at the start of a new segment. PCRE_INFO_MINLENGTH - If the pattern was studied and a minimum length for matching subject - strings was computed, its value is returned. Otherwise the returned + If the pattern was studied and a minimum length for matching subject + strings was computed, its value is returned. Otherwise the returned value is -1. The value is a number of characters, which in UTF mode may - be different from the number of data units. The fourth argument should - point to an int variable. A non-negative 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 + be different from the number of data units. The fourth argument should + point to an int variable. A non-negative 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. PCRE_INFO_NAMECOUNT PCRE_INFO_NAMEENTRYSIZE PCRE_INFO_NAMETABLE - PCRE supports the use of named as well as numbered capturing parenthe- - ses. The names are just an additional way of identifying the parenthe- + PCRE supports the use of named as well as numbered capturing parenthe- + ses. The names are just an additional way of identifying the parenthe- ses, which still acquire numbers. Several convenience functions such as - pcre_get_named_substring() 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 + pcre_get_named_substring() 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 pcre_exec() below). To do - the conversion, you need to use the name-to-number map, which is + 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. PCRE_INFO_NAMECOUNT gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size - of each entry; both of these return an int value. The entry size - depends on the length of the longest name. PCRE_INFO_NAMETABLE returns + of each entry; both of these return an int value. The entry size + depends on the length of the longest name. PCRE_INFO_NAMETABLE returns a pointer to the first entry of the table. This is a pointer to char in the 8-bit library, where the first two bytes of each entry are the num- - ber of the capturing parenthesis, most significant byte first. In the - 16-bit library, the pointer points to 16-bit data units, the first of - which contains the parenthesis number. In the 32-bit library, the - pointer points to 32-bit data units, the first of which contains the - parenthesis number. The rest of the entry is the corresponding name, + ber of the capturing parenthesis, most significant byte first. In the + 16-bit library, the pointer points to 16-bit data units, the first of + which contains the parenthesis number. In the 32-bit library, the + pointer points to 32-bit data 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. Duplicate names may appear if (?| - is used to create multiple groups with the same number, as described in - the section on duplicate subpattern numbers in the pcrepattern page. - Duplicate names for subpatterns with different numbers are permitted - only if PCRE_DUPNAMES is set. In all cases of duplicate names, they - appear in the table in the order in which they were found in the pat- - tern. In the absence of (?| this is the order of increasing number; - when (?| is used this is not necessarily the case because later subpat- - terns may have lower numbers. + 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 pcrepattern 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 PCRE_DUP- + NAMES 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 PCRE_EXTENDED is @@ -2923,27 +2978,15 @@ INFORMATION ABOUT A PATTERN PCRE_INFO_FIRSTCHARACTER - Return the fixed first character value, if PCRE_INFO_FIRSTCHARACTER- - FLAGS returned 1; otherwise returns 0. The fourth argument should point - to an uint_t variable. + Return the fixed first character value in the situation where + PCRE_INFO_FIRSTCHARACTERFLAGS returns 1; otherwise return 0. The fourth + argument should point to an uint_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. - If there is no fixed first value, and if either - - (a) the pattern was compiled with the PCRE_MULTILINE option, and every - branch starts with "^", or - - (b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not - set (if it were set, the pattern would be anchored), - - -1 is returned, indicating that the pattern matches only at the start - of a subject string or after any newline within the string. Otherwise - -2 is returned. For anchored patterns, -2 is returned. - PCRE_INFO_REQUIREDCHARFLAGS Returns 1 if there is a rightmost literal data unit that must exist in @@ -3132,16 +3175,20 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION The callout_data field is used in conjunction with the "callout" fea- ture, and is described in the pcrecallout documentation. - The tables field is used to pass a character tables pointer to - pcre_exec(); this overrides the value that is stored with the compiled - pattern. A non-NULL value is stored with the compiled pattern only if - custom tables were supplied to pcre_compile() via its tableptr argu- - ment. If NULL is passed to pcre_exec() using this mechanism, it forces - PCRE's internal tables to be used. This facility is helpful when re- - using patterns that have been saved after compiling with an external - set of tables, because the external tables might be at a different - address when pcre_exec() is called. See the pcreprecompile documenta- - tion for a discussion of saving compiled patterns for later use. + The tables field is provided for use with patterns that have been pre- + compiled using custom character tables, saved to disc or elsewhere, and + then reloaded, because the tables that were used to compile a pattern + are not saved with it. See the pcreprecompile documentation for a dis- + cussion of saving compiled patterns for later use. If NULL is passed + using this mechanism, it forces PCRE's internal tables to be used. + + Warning: The tables that pcre_exec() uses must be the same as those + that were used when the pattern was compiled. If this is not the case, + the behaviour of pcre_exec() is undefined. Therefore, when a pattern is + compiled and matched in the same process, this field should never be + set. In this (the most common) case, the correct table pointer is auto- + matically passed with the compiled pattern from pcre_compile() to + pcre_exec(). If PCRE_EXTRA_MARK is set in the flags field, the mark field must be set to point to a suitable variable. If the pattern contains any back- @@ -3350,7 +3397,7 @@ MATCHING A PATTERN: THE TRADITIONAL FUNCTION points to the start of a character (or the end of the subject). When PCRE_NO_UTF8_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. + may crash or loop. PCRE_PARTIAL_HARD PCRE_PARTIAL_SOFT @@ -4130,55 +4177,64 @@ MATCHING A PATTERN: THE ALTERNATIVE FUNCTION filled with the longest matches. Unlike pcre_exec(), pcre_dfa_exec() can use the entire ovector for returning matched strings. + NOTE: PCRE's "auto-possessification" optimization usually applies to + character repeats at the end of a pattern (as well as internally). For + example, the pattern "a\d+" is compiled as if it were "a\d++" because + there is no point even considering the possibility of backtracking into + the repeated digits. For DFA matching, this means that only one possi- + ble match is found. If you really do want multiple matches in such + cases, either use an ungreedy repeat ("a\d+?") or set the + PCRE_NO_AUTO_POSSESS option when compiling. + Error returns from pcre_dfa_exec() - The pcre_dfa_exec() function returns a negative number when it fails. - Many of the errors are the same as for pcre_exec(), and these are - described above. There are in addition the following errors that are + The pcre_dfa_exec() function returns a negative number when it fails. + Many of the errors are the same as for pcre_exec(), and these are + described above. There are in addition the following errors that are specific to pcre_dfa_exec(): PCRE_ERROR_DFA_UITEM (-16) - This return is given if pcre_dfa_exec() encounters an item in the pat- - tern that it does not support, for instance, the use of \C or a back + This return is given if pcre_dfa_exec() encounters an item in the pat- + tern that it does not support, for instance, the use of \C or a back reference. PCRE_ERROR_DFA_UCOND (-17) - This return is given if pcre_dfa_exec() encounters a condition item - that uses a back reference for the condition, or a test for recursion + This return is given if pcre_dfa_exec() encounters a condition item + that uses a back reference for the condition, or a test for recursion in a specific group. These are not supported. PCRE_ERROR_DFA_UMLIMIT (-18) - This return is given if pcre_dfa_exec() is called with an extra block - that contains a setting of the match_limit or match_limit_recursion - fields. This is not supported (these fields are meaningless for DFA + This return is given if pcre_dfa_exec() is called with an extra block + that contains a setting of the match_limit or match_limit_recursion + fields. This is not supported (these fields are meaningless for DFA matching). PCRE_ERROR_DFA_WSSIZE (-19) - This return is given if pcre_dfa_exec() runs out of space in the + This return is given if pcre_dfa_exec() runs out of space in the workspace vector. PCRE_ERROR_DFA_RECURSE (-20) - When a recursive subpattern is processed, the matching function calls - itself recursively, using private vectors for ovector and workspace. - This error is given if the output vector is not large enough. This + When a recursive subpattern is processed, the matching function calls + itself recursively, using private vectors for ovector and workspace. + This error is given if the output vector is not large enough. This should be extremely rare, as a vector of size 1000 is used. PCRE_ERROR_DFA_BADRESTART (-30) - When pcre_dfa_exec() is called with the PCRE_DFA_RESTART option, some - plausibility checks are made on the contents of the workspace, which - should contain data about the previous partial match. If any of these + When pcre_dfa_exec() is called with the PCRE_DFA_RESTART option, some + plausibility checks are made on the contents of the workspace, which + should contain data about the previous partial match. If any of these checks fail, this error is given. SEE ALSO - pcre16(3), pcre32(3), pcrebuild(3), pcrecallout(3), pcrecpp(3)(3), + pcre16(3), pcre32(3), pcrebuild(3), pcrecallout(3), pcrecpp(3)(3), pcrematching(3), pcrepartial(3), pcreposix(3), pcreprecompile(3), pcre- sample(3), pcrestack(3). @@ -4192,11 +4248,11 @@ AUTHOR REVISION - Last updated: 12 June 2013 + Last updated: 12 November 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRECALLOUT(3) Library Functions Manual PCRECALLOUT(3) @@ -4255,43 +4311,77 @@ DESCRIPTION independent groups). Automatic callouts can be used for tracking the progress of pattern - matching. The pcretest command has an option that sets automatic call- - outs; when it is used, the output indicates how the pattern is matched. - This is useful information when you are trying to optimize the perfor- - mance of a particular pattern. + matching. The pcretest program has a pattern qualifier (/C) that sets + automatic callouts; when it is used, the output indicates how the pat- + tern is being matched. This is useful information when you are trying + to optimize the performance of a particular pattern. MISSING CALLOUTS - You should be aware that, because of optimizations in the way PCRE - matches patterns by default, callouts sometimes do not happen. For - example, if the pattern is + You should be aware that, because of optimizations in the way PCRE com- + piles and matches patterns, callouts sometimes do not happen exactly as + you might expect. + + At compile time, PCRE "auto-possessifies" repeated items when it knows + that what follows cannot be part of the repeat. For example, a+[bc] is + compiled as if it were a++[bc]. The pcretest output when this pattern + is anchored and then applied with automatic callouts to the string + "aaaa" is: + + --->aaaa + +0 ^ ^ + +1 ^ a+ + +3 ^ ^ [bc] + No match + + This indicates that when matching [bc] fails, there is no backtracking + into a+ and therefore the callouts that would be taken for the back- + tracks do not occur. You can disable the auto-possessify feature by + passing PCRE_NO_AUTO_POSSESS to pcre_compile(), or starting the pattern + with (*NO_AUTO_POSSESS). If this is done in pcretest (using the /O + qualifier), the output changes to this: + + --->aaaa + +0 ^ ^ + +1 ^ a+ + +3 ^ ^ [bc] + +3 ^ ^ [bc] + +3 ^ ^ [bc] + +3 ^^ [bc] + No match + + This time, when matching [bc] fails, the matcher backtracks into a+ and + tries again, repeatedly, until a+ itself fails. + + Other optimizations that provide fast "no match" results also affect + callouts. For example, if the pattern is ab(?C4)cd PCRE knows that any matching string must contain the letter "d". If the - subject string is "abyz", the lack of "d" means that matching doesn't - ever start, and the callout is never reached. However, with "abyd", + subject string is "abyz", the lack of "d" means that matching doesn't + ever start, and the callout is never reached. However, with "abyd", though the result is still no match, the callout is obeyed. - If the pattern is studied, PCRE knows the minimum length of a matching - string, and will immediately give a "no match" return without actually - running a match if the subject is not long enough, or, for unanchored + If the pattern is studied, PCRE knows the minimum length of a matching + string, and will immediately give a "no match" return without actually + running a match if the subject is not long enough, or, for unanchored patterns, if it has been scanned far enough. - You can disable these optimizations by passing the PCRE_NO_START_OPTI- - MIZE option to the matching function, or by starting the pattern with - (*NO_START_OPT). This slows down the matching process, but does ensure + You can disable these optimizations by passing the PCRE_NO_START_OPTI- + MIZE option to the matching function, or by starting the pattern with + (*NO_START_OPT). This slows down the matching process, but does ensure that callouts such as the example above are obeyed. THE CALLOUT INTERFACE - During matching, when PCRE reaches a callout point, the external func- + During matching, when PCRE reaches a callout point, the external func- tion defined by pcre_callout or pcre[16|32]_callout is called (if it is - set). This applies to both normal and DFA matching. The only argument - to the callout function is a pointer to a pcre_callout or - pcre[16|32]_callout block. These structures contains the following + set). This applies to both normal and DFA matching. The only argument + to the callout function is a pointer to a pcre_callout or + pcre[16|32]_callout block. These structures contains the following fields: int version; @@ -4312,92 +4402,92 @@ THE CALLOUT INTERFACE const PCRE_UCHAR16 *mark; (16-bit version) const PCRE_UCHAR32 *mark; (32-bit version) - The version field is an integer containing the version number of the - block format. The initial version was 0; the current version is 2. The - version number will change again in future if additional fields are + The version field is an integer containing the version number of the + block format. The initial version was 0; the current version is 2. The + version number will change again in future if additional fields are added, but the intention is never to remove any of the existing fields. - The callout_number field contains the number of the callout, as com- - piled into the pattern (that is, the number after ?C for manual call- + The callout_number field contains the number of the callout, as com- + piled into the pattern (that is, the number after ?C for manual call- outs, and 255 for automatically generated callouts). - The offset_vector field is a pointer to the vector of offsets that was - passed by the caller to the matching function. When pcre_exec() or - pcre[16|32]_exec() is used, the contents can be inspected, in order to - extract substrings that have been matched so far, in the same way as - for extracting substrings after a match has completed. For the DFA + The offset_vector field is a pointer to the vector of offsets that was + passed by the caller to the matching function. When pcre_exec() or + pcre[16|32]_exec() is used, the contents can be inspected, in order to + extract substrings that have been matched so far, in the same way as + for extracting substrings after a match has completed. For the DFA matching functions, this field is not useful. The subject and subject_length fields contain copies of the values that were passed to the matching function. - The start_match field normally contains the offset within the subject - at which the current match attempt started. However, if the escape - sequence \K has been encountered, this value is changed to reflect the - modified starting point. If the pattern is not anchored, the callout + The start_match field normally contains the offset within the subject + at which the current match attempt started. However, if the escape + sequence \K has been encountered, this value is changed to reflect the + modified starting point. If the pattern is not anchored, the callout function may be called several times from the same point in the pattern for different starting points in the subject. - The current_position field contains the offset within the subject of + The current_position field contains the offset within the subject of the current match pointer. - When the pcre_exec() or pcre[16|32]_exec() is used, the capture_top - field contains one more than the number of the highest numbered cap- - tured substring so far. If no substrings have been captured, the value - of capture_top is one. This is always the case when the DFA functions + When the pcre_exec() or pcre[16|32]_exec() is used, the capture_top + field contains one more than the number of the highest numbered cap- + tured substring so far. If no substrings have been captured, the value + of capture_top is one. This is always the case when the DFA functions are used, because they do not support captured substrings. - The capture_last field contains the number of the most recently cap- - tured substring. However, when a recursion exits, the value reverts to - what it was outside the recursion, as do the values of all captured - substrings. If no substrings have been captured, the value of cap- - ture_last is -1. This is always the case for the DFA matching func- + The capture_last field contains the number of the most recently cap- + tured substring. However, when a recursion exits, the value reverts to + what it was outside the recursion, as do the values of all captured + substrings. If no substrings have been captured, the value of cap- + ture_last is -1. This is always the case for the DFA matching func- tions. - The callout_data field contains a value that is passed to a matching - function specifically so that it can be passed back in callouts. It is - passed in the callout_data field of a pcre_extra or pcre[16|32]_extra - data structure. If no such data was passed, the value of callout_data - in a callout block is NULL. There is a description of the pcre_extra + The callout_data field contains a value that is passed to a matching + function specifically so that it can be passed back in callouts. It is + passed in the callout_data field of a pcre_extra or pcre[16|32]_extra + data structure. If no such data was passed, the value of callout_data + in a callout block is NULL. There is a description of the pcre_extra structure in the pcreapi documentation. - The pattern_position field is present from version 1 of the callout + The pattern_position field is present from version 1 of the callout structure. It contains the offset to the next item to be matched in the pattern string. - The next_item_length field is present from version 1 of the callout + The next_item_length field is present from version 1 of the callout structure. It contains the length of the next item to be matched in the - pattern string. When the callout immediately precedes an alternation - bar, a closing parenthesis, or the end of the pattern, the length is - zero. When the callout precedes an opening parenthesis, the length is + pattern string. When the callout immediately precedes an alternation + bar, a closing parenthesis, or the end of the pattern, the length is + zero. When the callout precedes an opening parenthesis, the length is that of the entire subpattern. - The pattern_position and next_item_length fields are intended to help - in distinguishing between different automatic callouts, which all have + The pattern_position and next_item_length fields are intended to help + in distinguishing between different automatic callouts, which all have the same callout number. However, they are set for all callouts. - The mark field is present from version 2 of the callout structure. In - callouts from pcre_exec() or pcre[16|32]_exec() it contains a pointer - to the zero-terminated name of the most recently passed (*MARK), - (*PRUNE), or (*THEN) item in the match, or NULL if no such items have - been passed. Instances of (*PRUNE) or (*THEN) without a name do not - obliterate a previous (*MARK). In callouts from the DFA matching func- + The mark field is present from version 2 of the callout structure. In + callouts from pcre_exec() or pcre[16|32]_exec() it contains a pointer + to the zero-terminated name of the most recently passed (*MARK), + (*PRUNE), or (*THEN) item in the match, or NULL if no such items have + been passed. Instances of (*PRUNE) or (*THEN) without a name do not + obliterate a previous (*MARK). In callouts from the DFA matching func- tions this field always contains NULL. RETURN VALUES - The external callout function returns an integer to PCRE. If the value - is zero, matching proceeds as normal. If the value is greater than - zero, matching fails at the current point, but the testing of other + The external callout function returns an integer to PCRE. If the value + is zero, matching proceeds as normal. If the value is greater than + zero, matching fails at the current point, but the testing of other matching possibilities goes ahead, just as if a lookahead assertion had - failed. If the value is less than zero, the match is abandoned, the + failed. If the value is less than zero, the match is abandoned, the matching function returns the negative value. - Negative values should normally be chosen from the set of + Negative values should normally be chosen from the set of PCRE_ERROR_xxx values. In particular, PCRE_ERROR_NOMATCH forces a stan- - dard "no match" failure. The error number PCRE_ERROR_CALLOUT is - reserved for use by callout functions; it will never be used by PCRE + dard "no match" failure. The error number PCRE_ERROR_CALLOUT is + reserved for use by callout functions; it will never be used by PCRE itself. @@ -4410,11 +4500,11 @@ AUTHOR REVISION - Last updated: 03 March 2013 + Last updated: 12 November 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRECOMPAT(3) Library Functions Manual PCRECOMPAT(3) @@ -4532,17 +4622,23 @@ DIFFERENCES BETWEEN PCRE AND PERL 15. Perl recognizes comments in some places that PCRE does not, for example, between the ( and ? at the start of a subpattern. If the /x - modifier is set, Perl allows white space between ( and ? but PCRE never - does, even if the PCRE_EXTENDED option is set. + modifier is set, Perl allows white space between ( and ? (though cur- + rent Perls warn that this is deprecated) but PCRE never does, even if + the PCRE_EXTENDED option is set. + + 16. Perl, when in warning mode, gives warnings for character classes + such as [A-\d] or [a-[:digit:]]. It then treats the hyphens as liter- + als. PCRE has no warning features, so it gives an error in these cases + because they are almost certainly user mistakes. - 16. In PCRE, the upper/lower case character properties Lu and Ll are + 17. In PCRE, the upper/lower case character properties Lu and Ll are not affected when case-independent matching is specified. For example, \p{Lu} always matches an upper case letter. I think Perl has changed in this respect; in the release at the time of writing (5.16), \p{Lu} and \p{Ll} match all letters, regardless of case, when case independence is specified. - 17. PCRE provides some extensions to the Perl regular expression facil- + 18. PCRE provides some extensions to the Perl regular expression facil- ities. Perl 5.10 includes new features that are not in earlier ver- sions of Perl, some of which (such as named parentheses) have been in PCRE for some time. This list is with respect to Perl 5.10: @@ -4599,11 +4695,11 @@ AUTHOR REVISION - Last updated: 19 March 2013 + Last updated: 10 November 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREPATTERN(3) Library Functions Manual PCREPATTERN(3) @@ -4678,20 +4774,26 @@ SPECIAL START-OF-PATTERN ITEMS Unicode property support - Another special sequence that may appear at the start of a pattern is + Another special sequence that may appear at the start of a pattern is + (*UCP). This has the same effect as setting the PCRE_UCP option: it + causes sequences such as \d and \w to use Unicode properties to deter- + mine character types, instead of recognizing only characters with codes + less than 128 via a lookup table. - (*UCP) + Disabling auto-possessification - This has the same effect as setting the PCRE_UCP option: it causes - sequences such as \d and \w to use Unicode properties to determine - character types, instead of recognizing only characters with codes less - than 128 via a lookup table. + If a pattern starts with (*NO_AUTO_POSSESS), it has the same effect as + setting the PCRE_NO_AUTO_POSSESS option at compile time. This stops + PCRE from making quantifiers possessive when what follows cannot match + the repeated item. For example, by default a+b is treated as a++b. For + more details, see the pcreapi documentation. Disabling start-up optimizations - If a pattern starts with (*NO_START_OPT), it has the same effect as + If a pattern starts with (*NO_START_OPT), it has the same effect as setting the PCRE_NO_START_OPTIMIZE option either at compile or matching - time. + time. This disables several optimizations for quickly reaching "no + match" results. For more details, see the pcreapi documentation. Newline conventions @@ -4745,48 +4847,49 @@ SPECIAL START-OF-PATTERN ITEMS (*LIMIT_RECURSION=d) where d is any number of decimal digits. However, the value of the set- - ting must be less than the value set by the caller of pcre_exec() for - it to have any effect. In other words, the pattern writer can lower the - limit set by the programmer, but not raise it. If there is more than - one setting of one of these limits, the lower value is used. + ting must be less than the value set (or defaulted) by the caller of + pcre_exec() for it to have any effect. In other words, the pattern + writer can lower the limits set by the programmer, but not raise them. + If there is more than one setting of one of these limits, the lower + value is used. EBCDIC CHARACTER CODES - PCRE can be compiled to run in an environment that uses EBCDIC as its + PCRE can be compiled to run in an environment that uses EBCDIC as its character code rather than ASCII or Unicode (typically a mainframe sys- - tem). In the sections below, character code values are ASCII or Uni- + tem). In the sections below, character code values are ASCII or Uni- code; in an EBCDIC environment these characters may have different code values, and there are no code points greater than 255. CHARACTERS AND METACHARACTERS - A regular expression is a pattern that is matched against a subject - string from left to right. Most characters stand for themselves in a - pattern, and match the corresponding characters in the subject. As a + A regular expression is a pattern that is matched against a subject + string from left to right. Most characters stand for themselves in a + pattern, and match the corresponding characters in the subject. As a trivial example, the pattern The quick brown fox matches a portion of a subject string that is identical to itself. When - caseless matching is specified (the PCRE_CASELESS option), letters are - matched independently of case. In a UTF mode, PCRE always understands - the concept of case for characters whose values are less than 128, so - caseless matching is always possible. For characters with higher val- - ues, the concept of case is supported if PCRE is compiled with Unicode - property support, but not otherwise. If you want to use caseless - matching for characters 128 and above, you must ensure that PCRE is + caseless matching is specified (the PCRE_CASELESS option), letters are + matched independently of case. In a UTF mode, PCRE always understands + the concept of case for characters whose values are less than 128, so + caseless matching is always possible. For characters with higher val- + ues, the concept of case is supported if PCRE is compiled with Unicode + property support, but not otherwise. If you want to use caseless + matching for characters 128 and above, you must ensure that PCRE is compiled with Unicode property support as well as with UTF support. - The power of regular expressions comes from the ability to include - alternatives and repetitions in the pattern. These are encoded in the + The power of regular expressions comes from the ability to include + alternatives and repetitions in the pattern. These are encoded in the pattern by the use of metacharacters, which do not stand for themselves but instead are interpreted in some special way. - There are two different sets of metacharacters: those that are recog- - nized anywhere in the pattern except within square brackets, and those - that are recognized within square brackets. Outside square brackets, + There are two different sets of metacharacters: those that are recog- + nized anywhere in the pattern except within square brackets, and those + that are recognized within square brackets. Outside square brackets, the metacharacters are as follows: \ general escape character with several uses @@ -4805,7 +4908,7 @@ CHARACTERS AND METACHARACTERS also "possessive quantifier" { start min/max quantifier - Part of a pattern that is in square brackets is called a "character + Part of a pattern that is in square brackets is called a "character class". In a character class the only metacharacters are: \ general escape character @@ -4822,30 +4925,30 @@ BACKSLASH The backslash character has several uses. Firstly, if it is followed by a character that is not a number or a letter, it takes away any special - meaning that character may have. This use of backslash as an escape + meaning that character may have. This use of backslash as an escape character applies both inside and outside character classes. - For example, if you want to match a * character, you write \* in the - pattern. This escaping action applies whether or not the following - character would otherwise be interpreted as a metacharacter, so it is - always safe to precede a non-alphanumeric with backslash to specify - that it stands for itself. In particular, if you want to match a back- + For example, if you want to match a * character, you write \* in the + pattern. This escaping action applies whether or not the following + character would otherwise be interpreted as a metacharacter, so it is + always safe to precede a non-alphanumeric with backslash to specify + that it stands for itself. In particular, if you want to match a back- slash, you write \\. - In a UTF mode, only ASCII numbers and letters have any special meaning - after a backslash. All other characters (in particular, those whose + In a UTF mode, only ASCII numbers and letters have any special meaning + after a backslash. All other characters (in particular, those whose codepoints are greater than 127) are treated as literals. - If a pattern is compiled with the PCRE_EXTENDED option, white space in - the pattern (other than in a character class) and characters between a - # outside a character class and the next newline are ignored. An escap- - ing backslash can be used to include a white space or # character as - part of the pattern. + If a pattern is compiled with the PCRE_EXTENDED option, most white + space in the pattern (other than in a character class), and characters + between a # outside a character class and the next newline, inclusive, + are ignored. An escaping backslash can be used to include a white space + or # character as part of the pattern. - If you want to remove the special meaning from a sequence of charac- - ters, you can do so by putting them between \Q and \E. This is differ- - ent from Perl in that $ and @ are handled as literals in \Q...\E - sequences in PCRE, whereas in Perl, $ and @ cause variable interpola- + If you want to remove the special meaning from a sequence of charac- + ters, you can do so by putting them between \Q and \E. This is differ- + ent from Perl in that $ and @ are handled as literals in \Q...\E + sequences in PCRE, whereas in Perl, $ and @ cause variable interpola- tion. Note the following examples: Pattern PCRE matches Perl matches @@ -4855,20 +4958,20 @@ BACKSLASH \Qabc\$xyz\E abc\$xyz abc\$xyz \Qabc\E\$\Qxyz\E abc$xyz abc$xyz - The \Q...\E sequence is recognized both inside and outside character - classes. An isolated \E that is not preceded by \Q is ignored. If \Q - is not followed by \E later in the pattern, the literal interpretation - continues to the end of the pattern (that is, \E is assumed at the - end). If the isolated \Q is inside a character class, this causes an + The \Q...\E sequence is recognized both inside and outside character + classes. An isolated \E that is not preceded by \Q is ignored. If \Q + is not followed by \E later in the pattern, the literal interpretation + continues to the end of the pattern (that is, \E is assumed at the + end). If the isolated \Q is inside a character class, this causes an error, because the character class is not terminated. Non-printing characters A second use of backslash provides a way of encoding non-printing char- - acters in patterns in a visible manner. There is no restriction on the - appearance of non-printing characters, apart from the binary zero that - terminates a pattern, but when a pattern is being prepared by text - editing, it is often easier to use one of the following escape + acters in patterns in a visible manner. There is no restriction on the + appearance of non-printing characters, apart from the binary zero that + terminates a pattern, but when a pattern is being prepared by text + editing, it is often easier to use one of the following escape sequences than the binary character it represents: \a alarm, that is, the BEL character (hex 07) @@ -4878,84 +4981,63 @@ BACKSLASH \n linefeed (hex 0A) \r carriage return (hex 0D) \t tab (hex 09) + \0dd character with octal code 0dd \ddd character with octal code ddd, or back reference + \o{ddd..} character with octal code ddd.. \xhh character with hex code hh \x{hhh..} character with hex code hhh.. (non-JavaScript mode) \uhhhh character with hex code hhhh (JavaScript mode only) - The precise effect of \cx on ASCII characters is as follows: if x is a - lower case letter, it is converted to upper case. Then bit 6 of the + The precise effect of \cx on ASCII characters is as follows: if x is a + lower case letter, it is converted to upper case. Then bit 6 of the character (hex 40) is inverted. Thus \cA to \cZ become hex 01 to hex 1A - (A is 41, Z is 5A), but \c{ becomes hex 3B ({ is 7B), and \c; becomes - hex 7B (; is 3B). If the data item (byte or 16-bit value) following \c - has a value greater than 127, a compile-time error occurs. This locks + (A is 41, Z is 5A), but \c{ becomes hex 3B ({ is 7B), and \c; becomes + hex 7B (; is 3B). If the data item (byte or 16-bit value) following \c + has a value greater than 127, a compile-time error occurs. This locks out non-ASCII characters in all modes. - The \c facility was designed for use with ASCII characters, but with - the extension to Unicode it is even less useful than it once was. It - is, however, recognized when PCRE is compiled in EBCDIC mode, where - data items are always bytes. In this mode, all values are valid after - \c. If the next character is a lower case letter, it is converted to - upper case. Then the 0xc0 bits of the byte are inverted. Thus \cA - becomes hex 01, as in ASCII (A is C1), but because the EBCDIC letters - are disjoint, \cZ becomes hex 29 (Z is E9), and other characters also + The \c facility was designed for use with ASCII characters, but with + the extension to Unicode it is even less useful than it once was. It + is, however, recognized when PCRE is compiled in EBCDIC mode, where + data items are always bytes. In this mode, all values are valid after + \c. If the next character is a lower case letter, it is converted to + upper case. Then the 0xc0 bits of the byte are inverted. Thus \cA + becomes hex 01, as in ASCII (A is C1), but because the EBCDIC letters + are disjoint, \cZ becomes hex 29 (Z is E9), and other characters also generate different values. - By default, after \x, from zero to two hexadecimal digits are read - (letters can be in upper or lower case). Any number of hexadecimal dig- - its may appear between \x{ and }, but the character code is constrained - as follows: - - 8-bit non-UTF mode less than 0x100 - 8-bit UTF-8 mode less than 0x10ffff and a valid codepoint - 16-bit non-UTF mode less than 0x10000 - 16-bit UTF-16 mode less than 0x10ffff and a valid codepoint - 32-bit non-UTF mode less than 0x80000000 - 32-bit UTF-32 mode less than 0x10ffff and a valid codepoint - - Invalid Unicode codepoints are the range 0xd800 to 0xdfff (the so- - called "surrogate" codepoints), and 0xffef. - - If characters other than hexadecimal digits appear between \x{ and }, - or if there is no terminating }, this form of escape is not recognized. - Instead, the initial \x will be interpreted as a basic hexadecimal - escape, with no following digits, giving a character whose value is - zero. - - If the PCRE_JAVASCRIPT_COMPAT option is set, the interpretation of \x - is as just described only when it is followed by two hexadecimal dig- - its. Otherwise, it matches a literal "x" character. In JavaScript - mode, support for code points greater than 256 is provided by \u, which - must be followed by four hexadecimal digits; otherwise it matches a - literal "u" character. Character codes specified by \u in JavaScript - mode are constrained in the same was as those specified by \x in non- - JavaScript mode. - - Characters whose value is less than 256 can be defined by either of the - two syntaxes for \x (or by \u in JavaScript mode). There is no differ- - ence in the way they are handled. For example, \xdc is exactly the same - as \x{dc} (or \u00dc in JavaScript mode). - - After \0 up to two further octal digits are read. If there are fewer - than two digits, just those that are present are used. Thus the + After \0 up to two further octal digits are read. If there are fewer + than two digits, just those that are present are used. Thus the sequence \0\x\07 specifies two binary zeros followed by a BEL character - (code value 7). Make sure you supply two digits after the initial zero + (code value 7). Make sure you supply two digits after the initial zero if the pattern character that follows is itself an octal digit. + The escape \o must be followed by a sequence of octal digits, enclosed + in braces. An error occurs if this is not the case. This escape is a + recent addition to Perl; it provides way of specifying character code + points as octal numbers greater than 0777, and it also allows octal + numbers and back references to be unambiguously specified. + + For greater clarity and unambiguity, it is best to avoid following \ by + a digit greater than zero. Instead, use \o{} or \x{} to specify charac- + ter numbers, and \g{} to specify back references. The following para- + graphs describe the old, ambiguous syntax. + The handling of a backslash followed by a digit other than 0 is compli- - cated. Outside a character class, PCRE reads it and any following dig- - its as a decimal number. If the number is less than 10, or if there - have been at least that many previous capturing left parentheses in the - expression, the entire sequence is taken as a back reference. A - description of how this works is given later, following the discussion + cated, and Perl has changed in recent releases, causing PCRE also to + change. Outside a character class, PCRE reads the digit and any follow- + ing digits as a decimal number. If the number is less than 8, or if + there have been at least that many previous capturing left parentheses + in the expression, the entire sequence is taken as a back reference. A + description of how this works is given later, following the discussion of parenthesized subpatterns. - Inside a character class, or if the decimal number is greater than 9 - and there have not been that many capturing subpatterns, PCRE re-reads - up to three octal digits following the backslash, and uses them to gen- - erate a data character. Any subsequent digits stand for themselves. The - value of the character is constrained in the same way as characters - specified in hexadecimal. For example: + Inside a character class, or if the decimal number following \ is + greater than 7 and there have not been that many capturing subpatterns, + PCRE handles \8 and \9 as the literal characters "8" and "9", and oth- + erwise re-reads up to three octal digits following the backslash, using + them to generate a data character. Any subsequent digits stand for + themselves. For example: \040 is another way of writing an ASCII space \40 is the same, provided there are fewer than 40 @@ -4969,11 +5051,47 @@ BACKSLASH character with octal code 113 \377 might be a back reference, otherwise the value 255 (decimal) - \81 is either a back reference, or a binary zero - followed by the two characters "8" and "1" + \81 is either a back reference, or the two + characters "8" and "1" - Note that octal values of 100 or greater must not be introduced by a - leading zero, because no more than three octal digits are ever read. + Note that octal values of 100 or greater that are specified using this + syntax must not be introduced by a leading zero, because no more than + three octal digits are ever read. + + By default, after \x that is not followed by {, from zero to two hexa- + decimal digits are read (letters can be in upper or lower case). Any + number of hexadecimal digits may appear between \x{ and }. If a charac- + ter other than a hexadecimal digit appears between \x{ and }, or if + there is no terminating }, an error occurs. + + If the PCRE_JAVASCRIPT_COMPAT option is set, the interpretation of \x + is as just described only when it is followed by two hexadecimal dig- + its. Otherwise, it matches a literal "x" character. In JavaScript + mode, support for code points greater than 256 is provided by \u, which + must be followed by four hexadecimal digits; otherwise it matches a + literal "u" character. + + Characters whose value is less than 256 can be defined by either of the + two syntaxes for \x (or by \u in JavaScript mode). There is no differ- + ence in the way they are handled. For example, \xdc is exactly the same + as \x{dc} (or \u00dc in JavaScript mode). + + Constraints on character values + + Characters that are specified using octal or hexadecimal numbers are + limited to certain values, as follows: + + 8-bit non-UTF mode less than 0x100 + 8-bit UTF-8 mode less than 0x10ffff and a valid codepoint + 16-bit non-UTF mode less than 0x10000 + 16-bit UTF-16 mode less than 0x10ffff and a valid codepoint + 32-bit non-UTF mode less than 0x100000000 + 32-bit UTF-32 mode less than 0x10ffff and a valid codepoint + + Invalid Unicode codepoints are the range 0xd800 to 0xdfff (the so- + called "surrogate" codepoints), and 0xffef. + + Escape sequences in character classes All the sequences that define a single character value can be used both inside and outside character classes. In addition, inside a character @@ -5038,32 +5156,36 @@ BACKSLASH the subject string, all of them fail, because there is no character to match. - For compatibility with Perl, \s does not match the VT character (code - 11). This makes it different from the the POSIX "space" class. The \s - characters are HT (9), LF (10), FF (12), CR (13), and space (32). If - "use locale;" is included in a Perl script, \s may match the VT charac- - ter. In PCRE, it never does. - - A "word" character is an underscore or any character that is a letter - or digit. By default, the definition of letters and digits is con- - trolled by PCRE's low-valued character tables, and may vary if locale- - specific matching is taking place (see "Locale support" in the pcreapi - page). For example, in a French locale such as "fr_FR" in Unix-like - systems, or "french" in Windows, some character codes greater than 128 - are used for accented letters, and these are then matched by \w. The + For compatibility with Perl, \s did not used to match the VT character + (code 11), which made it different from the the POSIX "space" class. + However, Perl added VT at release 5.18, and PCRE followed suit at + release 8.34. The default \s characters are now HT (9), LF (10), VT + (11), FF (12), CR (13), and space (32), which are defined as white + space in the "C" locale. This list may vary if locale-specific matching + is taking place; in particular, in some locales the "non-breaking + space" character (\xA0) is recognized as white space. + + A "word" character is an underscore or any character that is a letter + or digit. By default, the definition of letters and digits is con- + trolled by PCRE's low-valued character tables, and may vary if locale- + specific matching is taking place (see "Locale support" in the pcreapi + page). For example, in a French locale such as "fr_FR" in Unix-like + systems, or "french" in Windows, some character codes greater than 127 + are used for accented letters, and these are then matched by \w. The use of locales with Unicode is discouraged. - By default, in a UTF mode, characters with values greater than 128 - never match \d, \s, or \w, and always match \D, \S, and \W. These - sequences retain their original meanings from before UTF support was - available, mainly for efficiency reasons. However, if PCRE is compiled - with Unicode property support, and the PCRE_UCP option is set, the be- - haviour is changed so that Unicode properties are used to determine - character types, as follows: + By default, characters whose code points are greater than 127 never + match \d, \s, or \w, and always match \D, \S, and \W, although this may + vary for characters in the range 128-255 when locale-specific matching + is happening. These escape sequences retain their original meanings + from before Unicode support was available, mainly for efficiency rea- + sons. If PCRE is compiled with Unicode property support, and the + PCRE_UCP option is set, the behaviour is changed so that Unicode prop- + erties are used to determine character types, as follows: - \d any character that \p{Nd} matches (decimal digit) - \s any character that \p{Z} matches, plus HT, LF, FF, CR - \w any character that \p{L} or \p{N} matches, plus underscore + \d any character that matches \p{Nd} (decimal digit) + \s any character that matches \p{Z} or \h or \v + \w any character that matches \p{L} or \p{N}, plus underscore The upper case escapes match the inverse sets of characters. Note that \d matches only decimal digits, whereas \w matches any Unicode digit, @@ -5074,7 +5196,7 @@ BACKSLASH The sequences \h, \H, \v, and \V are features that were added to Perl at release 5.10. In contrast to the other sequences, which match only ASCII characters by default, these always match certain high-valued - codepoints, whether or not PCRE_UCP is set. The horizontal space char- + code points, whether or not PCRE_UCP is set. The horizontal space char- acters are: U+0009 Horizontal tab (HT) @@ -5340,60 +5462,61 @@ BACKSLASH As well as the standard Unicode properties described above, PCRE sup- ports four more that make it possible to convert traditional escape - sequences such as \w and \s and POSIX character classes to use Unicode - properties. PCRE uses these non-standard, non-Perl properties inter- - nally when PCRE_UCP is set. However, they may also be used explicitly. - These properties are: + sequences such as \w and \s to use Unicode properties. PCRE uses these + non-standard, non-Perl properties internally when PCRE_UCP is set. How- + ever, they may also be used explicitly. These properties are: Xan Any alphanumeric character Xps Any POSIX space character Xsp Any Perl space character Xwd Any Perl "word" character - Xan matches characters that have either the L (letter) or the N (num- - ber) property. Xps matches the characters tab, linefeed, vertical tab, - form feed, or carriage return, and any other character that has the Z - (separator) property. Xsp is the same as Xps, except that vertical tab - is excluded. Xwd matches the same characters as Xan, plus underscore. - - There is another non-standard property, Xuc, which matches any charac- - ter that can be represented by a Universal Character Name in C++ and - other programming languages. These are the characters $, @, ` (grave - accent), and all characters with Unicode code points greater than or - equal to U+00A0, except for the surrogates U+D800 to U+DFFF. Note that - most base (ASCII) characters are excluded. (Universal Character Names - are of the form \uHHHH or \UHHHHHHHH where H is a hexadecimal digit. + Xan matches characters that have either the L (letter) or the N (num- + ber) property. Xps matches the characters tab, linefeed, vertical tab, + form feed, or carriage return, and any other character that has the Z + (separator) property. Xsp is the same as Xps; it used to exclude ver- + tical tab, for Perl compatibility, but Perl changed, and so PCRE fol- + lowed at release 8.34. Xwd matches the same characters as Xan, plus + underscore. + + There is another non-standard property, Xuc, which matches any charac- + ter that can be represented by a Universal Character Name in C++ and + other programming languages. These are the characters $, @, ` (grave + accent), and all characters with Unicode code points greater than or + equal to U+00A0, except for the surrogates U+D800 to U+DFFF. Note that + most base (ASCII) characters are excluded. (Universal Character Names + are of the form \uHHHH or \UHHHHHHHH where H is a hexadecimal digit. Note that the Xuc property does not match these sequences but the char- acters that they represent.) Resetting the match start - The escape sequence \K causes any previously matched characters not to + The escape sequence \K causes any previously matched characters not to be included in the final matched sequence. For example, the pattern: foo\Kbar - matches "foobar", but reports that it has matched "bar". This feature - is similar to a lookbehind assertion (described below). However, in - this case, the part of the subject before the real match does not have - to be of fixed length, as lookbehind assertions do. The use of \K does - not interfere with the setting of captured substrings. For example, + matches "foobar", but reports that it has matched "bar". This feature + is similar to a lookbehind assertion (described below). However, in + this case, the part of the subject before the real match does not have + to be of fixed length, as lookbehind assertions do. The use of \K does + not interfere with the setting of captured substrings. For example, when the pattern (foo)\Kbar matches "foobar", the first substring is still set to "foo". - Perl documents that the use of \K within assertions is "not well - defined". In PCRE, \K is acted upon when it occurs inside positive + Perl documents that the use of \K within assertions is "not well + defined". In PCRE, \K is acted upon when it occurs inside positive assertions, but is ignored in negative assertions. Simple assertions - The final use of backslash is for certain simple assertions. An asser- - tion specifies a condition that has to be met at a particular point in - a match, without consuming any characters from the subject string. The - use of subpatterns for more complicated assertions is described below. + The final use of backslash is for certain simple assertions. An asser- + tion specifies a condition that has to be met at a particular point in + a match, without consuming any characters from the subject string. The + use of subpatterns for more complicated assertions is described below. The backslashed assertions are: \b matches at a word boundary @@ -5404,161 +5527,161 @@ BACKSLASH \z matches only at the end of the subject \G matches at the first matching position in the subject - Inside a character class, \b has a different meaning; it matches the - backspace character. If any other of these assertions appears in a - character class, by default it matches the corresponding literal char- + Inside a character class, \b has a different meaning; it matches the + backspace character. If any other of these assertions appears in a + character class, by default it matches the corresponding literal char- acter (for example, \B matches the letter B). However, if the - PCRE_EXTRA option is set, an "invalid escape sequence" error is gener- + PCRE_EXTRA option is set, an "invalid escape sequence" error is gener- ated instead. - A word boundary is a position in the subject string where the current - character and the previous character do not both match \w or \W (i.e. - one matches \w and the other matches \W), or the start or end of the - string if the first or last character matches \w, respectively. In a - UTF mode, the meanings of \w and \W can be changed by setting the - PCRE_UCP option. When this is done, it also affects \b and \B. Neither - PCRE nor Perl has a separate "start of word" or "end of word" metase- - quence. However, whatever follows \b normally determines which it is. + A word boundary is a position in the subject string where the current + character and the previous character do not both match \w or \W (i.e. + one matches \w and the other matches \W), or the start or end of the + string if the first or last character matches \w, respectively. In a + UTF mode, the meanings of \w and \W can be changed by setting the + PCRE_UCP option. When this is done, it also affects \b and \B. Neither + PCRE nor Perl has a separate "start of word" or "end of word" metase- + quence. However, whatever follows \b normally determines which it is. For example, the fragment \ba matches "a" at the start of a word. - The \A, \Z, and \z assertions differ from the traditional circumflex + The \A, \Z, and \z assertions differ from the traditional circumflex and dollar (described in the next section) in that they only ever match - at the very start and end of the subject string, whatever options are - set. Thus, they are independent of multiline mode. These three asser- + at the very start and end of the subject string, whatever options are + set. Thus, they are independent of multiline mode. These three asser- tions are not affected by the PCRE_NOTBOL or PCRE_NOTEOL options, which - affect only the behaviour of the circumflex and dollar metacharacters. - However, if the startoffset argument of pcre_exec() is non-zero, indi- + affect only the behaviour of the circumflex and dollar metacharacters. + However, if the startoffset argument of pcre_exec() is non-zero, indi- cating that matching is to start at a point other than the beginning of - the subject, \A can never match. The difference between \Z and \z is + the subject, \A can never match. The difference between \Z and \z is that \Z matches before a newline at the end of the string as well as at the very end, whereas \z matches only at the end. - The \G assertion is true only when the current matching position is at - the start point of the match, as specified by the startoffset argument - of pcre_exec(). It differs from \A when the value of startoffset is - non-zero. By calling pcre_exec() multiple times with appropriate argu- + The \G assertion is true only when the current matching position is at + the start point of the match, as specified by the startoffset argument + of pcre_exec(). It differs from \A when the value of startoffset is + non-zero. By calling pcre_exec() multiple times with appropriate argu- ments, you can mimic Perl's /g option, and it is in this kind of imple- mentation where \G can be useful. - Note, however, that PCRE's interpretation of \G, as the start of the + Note, however, that PCRE's interpretation of \G, as the start of the current match, is subtly different from Perl's, which defines it as the - end of the previous match. In Perl, these can be different when the - previously matched string was empty. Because PCRE does just one match + end of the previous match. In Perl, these can be different when the + previously matched string was empty. Because PCRE does just one match at a time, it cannot reproduce this behaviour. - If all the alternatives of a pattern begin with \G, the expression is + If all the alternatives of a pattern begin with \G, the expression is anchored to the starting match position, and the "anchored" flag is set in the compiled regular expression. CIRCUMFLEX AND DOLLAR - The circumflex and dollar metacharacters are zero-width assertions. - That is, they test for a particular condition being true without con- + The circumflex and dollar metacharacters are zero-width assertions. + That is, they test for a particular condition being true without con- suming any characters from the subject string. Outside a character class, in the default matching mode, the circumflex - character is an assertion that is true only if the current matching - point is at the start of the subject string. If the startoffset argu- - ment of pcre_exec() is non-zero, circumflex can never match if the - PCRE_MULTILINE option is unset. Inside a character class, circumflex + character is an assertion that is true only if the current matching + point is at the start of the subject string. If the startoffset argu- + ment of pcre_exec() is non-zero, circumflex can never match if the + PCRE_MULTILINE option is unset. Inside a character class, circumflex has an entirely different meaning (see below). - Circumflex need not be the first character of the pattern if a number - of alternatives are involved, but it should be the first thing in each - alternative in which it appears if the pattern is ever to match that - branch. If all possible alternatives start with a circumflex, that is, - if the pattern is constrained to match only at the start of the sub- - ject, it is said to be an "anchored" pattern. (There are also other + Circumflex need not be the first character of the pattern if a number + of alternatives are involved, but it should be the first thing in each + alternative in which it appears if the pattern is ever to match that + branch. If all possible alternatives start with a circumflex, that is, + if the pattern is constrained to match only at the start of the sub- + ject, it is said to be an "anchored" pattern. (There are also other constructs that can cause a pattern to be anchored.) - The dollar character is an assertion that is true only if the current - matching point is at the end of the subject string, or immediately - before a newline at the end of the string (by default). Note, however, - that it does not actually match the newline. Dollar need not be the + The dollar character is an assertion that is true only if the current + matching point is at the end of the subject string, or immediately + before a newline at the end of the string (by default). Note, however, + that it does not actually match the newline. Dollar need not be the last character of the pattern if a number of alternatives are involved, - but it should be the last item in any branch in which it appears. Dol- + but it should be the last item in any branch in which it appears. Dol- lar has no special meaning in a character class. - The meaning of dollar can be changed so that it matches only at the - very end of the string, by setting the PCRE_DOLLAR_ENDONLY option at + The meaning of dollar can be changed so that it matches only at the + very end of the string, by setting the PCRE_DOLLAR_ENDONLY option at compile time. This does not affect the \Z assertion. The meanings of the circumflex and dollar characters are changed if the - PCRE_MULTILINE option is set. When this is the case, a circumflex - matches immediately after internal newlines as well as at the start of - the subject string. It does not match after a newline that ends the - string. A dollar matches before any newlines in the string, as well as - at the very end, when PCRE_MULTILINE is set. When newline is specified - as the two-character sequence CRLF, isolated CR and LF characters do + PCRE_MULTILINE option is set. When this is the case, a circumflex + matches immediately after internal newlines as well as at the start of + the subject string. It does not match after a newline that ends the + string. A dollar matches before any newlines in the string, as well as + at the very end, when PCRE_MULTILINE is set. When newline is specified + as the two-character sequence CRLF, isolated CR and LF characters do not indicate newlines. - For example, the pattern /^abc$/ matches the subject string "def\nabc" - (where \n represents a newline) in multiline mode, but not otherwise. - Consequently, patterns that are anchored in single line mode because - all branches start with ^ are not anchored in multiline mode, and a - match for circumflex is possible when the startoffset argument of - pcre_exec() is non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if + For example, the pattern /^abc$/ matches the subject string "def\nabc" + (where \n represents a newline) in multiline mode, but not otherwise. + Consequently, patterns that are anchored in single line mode because + all branches start with ^ are not anchored in multiline mode, and a + match for circumflex is possible when the startoffset argument of + pcre_exec() is non-zero. The PCRE_DOLLAR_ENDONLY option is ignored if PCRE_MULTILINE is set. - Note that the sequences \A, \Z, and \z can be used to match the start - and end of the subject in both modes, and if all branches of a pattern - start with \A it is always anchored, whether or not PCRE_MULTILINE is + Note that the sequences \A, \Z, and \z can be used to match the start + and end of the subject in both modes, and if all branches of a pattern + start with \A it is always anchored, whether or not PCRE_MULTILINE is set. FULL STOP (PERIOD, DOT) AND \N Outside a character class, a dot in the pattern matches any one charac- - ter in the subject string except (by default) a character that signi- + ter in the subject string except (by default) a character that signi- fies the end of a line. - When a line ending is defined as a single character, dot never matches - that character; when the two-character sequence CRLF is used, dot does - not match CR if it is immediately followed by LF, but otherwise it - matches all characters (including isolated CRs and LFs). When any Uni- - code line endings are being recognized, dot does not match CR or LF or + When a line ending is defined as a single character, dot never matches + that character; when the two-character sequence CRLF is used, dot does + not match CR if it is immediately followed by LF, but otherwise it + matches all characters (including isolated CRs and LFs). When any Uni- + code line endings are being recognized, dot does not match CR or LF or any of the other line ending characters. - The behaviour of dot with regard to newlines can be changed. If the - PCRE_DOTALL option is set, a dot matches any one character, without + The behaviour of dot with regard to newlines can be changed. If the + PCRE_DOTALL option is set, a dot matches any one character, without exception. If the two-character sequence CRLF is present in the subject string, it takes two dots to match it. - The handling of dot is entirely independent of the handling of circum- - flex and dollar, the only relationship being that they both involve + The handling of dot is entirely independent of the handling of circum- + flex and dollar, the only relationship being that they both involve newlines. Dot has no special meaning in a character class. - The escape sequence \N behaves like a dot, except that it is not - affected by the PCRE_DOTALL option. In other words, it matches any - character except one that signifies the end of a line. Perl also uses + The escape sequence \N behaves like a dot, except that it is not + affected by the PCRE_DOTALL option. In other words, it matches any + character except one that signifies the end of a line. Perl also uses \N to match characters by name; PCRE does not support this. MATCHING A SINGLE DATA UNIT - Outside a character class, the escape sequence \C matches any one data - unit, whether or not a UTF mode is set. In the 8-bit library, one data - unit is one byte; in the 16-bit library it is a 16-bit unit; in the - 32-bit library it is a 32-bit unit. Unlike a dot, \C always matches - line-ending characters. The feature is provided in Perl in order to + Outside a character class, the escape sequence \C matches any one data + unit, whether or not a UTF mode is set. In the 8-bit library, one data + unit is one byte; in the 16-bit library it is a 16-bit unit; in the + 32-bit library it is a 32-bit unit. Unlike a dot, \C always matches + line-ending characters. The feature is provided in Perl in order to match individual bytes in UTF-8 mode, but it is unclear how it can use- - fully be used. Because \C breaks up characters into individual data - units, matching one unit with \C in a UTF mode means that the rest of + fully be used. Because \C breaks up characters into individual data + units, matching one unit with \C in a UTF mode means that the rest of the string may start with a malformed UTF character. This has undefined results, because PCRE assumes that it is dealing with valid UTF strings - (and by default it checks this at the start of processing unless the - PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK or PCRE_NO_UTF32_CHECK option + (and by default it checks this at the start of processing unless the + PCRE_NO_UTF8_CHECK, PCRE_NO_UTF16_CHECK or PCRE_NO_UTF32_CHECK option is used). - PCRE does not allow \C to appear in lookbehind assertions (described - below) in a UTF mode, because this would make it impossible to calcu- + PCRE does not allow \C to appear in lookbehind assertions (described + below) in a UTF mode, because this would make it impossible to calcu- late the length of the lookbehind. In general, the \C escape sequence is best avoided. However, one way of - using it that avoids the problem of malformed UTF characters is to use - a lookahead to check the length of the next character, as in this pat- - tern, which could be used with a UTF-8 string (ignore white space and + using it that avoids the problem of malformed UTF characters is to use + a lookahead to check the length of the next character, as in this pat- + tern, which could be used with a UTF-8 string (ignore white space and line breaks): (?| (?=[\x00-\x7f])(\C) | @@ -5566,11 +5689,11 @@ MATCHING A SINGLE DATA UNIT (?=[\x{800}-\x{ffff}])(\C)(\C)(\C) | (?=[\x{10000}-\x{1fffff}])(\C)(\C)(\C)(\C)) - A group that starts with (?| resets the capturing parentheses numbers - in each alternative (see "Duplicate Subpattern Numbers" below). The - assertions at the start of each branch check the next UTF-8 character - for values whose encoding uses 1, 2, 3, or 4 bytes, respectively. The - character's individual bytes are then captured by the appropriate num- + A group that starts with (?| resets the capturing parentheses numbers + in each alternative (see "Duplicate Subpattern Numbers" below). The + assertions at the start of each branch check the next UTF-8 character + for values whose encoding uses 1, 2, 3, or 4 bytes, respectively. The + character's individual bytes are then captured by the appropriate num- ber of groups. @@ -5580,64 +5703,71 @@ SQUARE BRACKETS AND CHARACTER CLASSES closing square bracket. A closing square bracket on its own is not spe- cial by default. However, if the PCRE_JAVASCRIPT_COMPAT option is set, a lone closing square bracket causes a compile-time error. If a closing - square bracket is required as a member of the class, it should be the - first data character in the class (after an initial circumflex, if + square bracket is required as a member of the class, it should be the + first data character in the class (after an initial circumflex, if present) or escaped with a backslash. - A character class matches a single character in the subject. In a UTF - mode, the character may be more than one data unit long. A matched + A character class matches a single character in the subject. In a UTF + mode, the character may be more than one data unit long. A matched character must be in the set of characters defined by the class, unless - the first character in the class definition is a circumflex, in which + the first character in the class definition is a circumflex, in which case the subject character must not be in the set defined by the class. - If a circumflex is actually required as a member of the class, ensure + If a circumflex is actually required as a member of the class, ensure it is not the first character, or escape it with a backslash. - For example, the character class [aeiou] matches any lower case vowel, - while [^aeiou] matches any character that is not a lower case vowel. + For example, the character class [aeiou] matches any lower case vowel, + while [^aeiou] matches any character that is not a lower case vowel. Note that a circumflex is just a convenient notation for specifying the - characters that are in the class by enumerating those that are not. A - class that starts with a circumflex is not an assertion; it still con- - sumes a character from the subject string, and therefore it fails if + characters that are in the class by enumerating those that are not. A + class that starts with a circumflex is not an assertion; it still con- + sumes a character from the subject string, and therefore it fails if the current pointer is at the end of the string. In UTF-8 (UTF-16, UTF-32) mode, characters with values greater than 255 - (0xffff) can be included in a class as a literal string of data units, + (0xffff) can be included in a class as a literal string of data units, or by using the \x{ escaping mechanism. - When caseless matching is set, any letters in a class represent both - their upper case and lower case versions, so for example, a caseless - [aeiou] matches "A" as well as "a", and a caseless [^aeiou] does not - match "A", whereas a caseful version would. In a UTF mode, PCRE always - understands the concept of case for characters whose values are less - than 128, so caseless matching is always possible. For characters with - higher values, the concept of case is supported if PCRE is compiled - with Unicode property support, but not otherwise. If you want to use - caseless matching in a UTF mode for characters 128 and above, you must - ensure that PCRE is compiled with Unicode property support as well as + When caseless matching is set, any letters in a class represent both + their upper case and lower case versions, so for example, a caseless + [aeiou] matches "A" as well as "a", and a caseless [^aeiou] does not + match "A", whereas a caseful version would. In a UTF mode, PCRE always + understands the concept of case for characters whose values are less + than 128, so caseless matching is always possible. For characters with + higher values, the concept of case is supported if PCRE is compiled + with Unicode property support, but not otherwise. If you want to use + caseless matching in a UTF mode for characters 128 and above, you must + ensure that PCRE is compiled with Unicode property support as well as with UTF support. - Characters that might indicate line breaks are never treated in any - special way when matching character classes, whatever line-ending - sequence is in use, and whatever setting of the PCRE_DOTALL and + Characters that might indicate line breaks are never treated in any + special way when matching character classes, whatever line-ending + sequence is in use, and whatever setting of the PCRE_DOTALL and PCRE_MULTILINE options is used. A class such as [^a] always matches one of these characters. - The minus (hyphen) character can be used to specify a range of charac- - ters in a character class. For example, [d-m] matches any letter - between d and m, inclusive. If a minus character is required in a - class, it must be escaped with a backslash or appear in a position - where it cannot be interpreted as indicating a range, typically as the - first or last character in the class. + The minus (hyphen) character can be used to specify a range of charac- + ters in a character class. For example, [d-m] matches any letter + between d and m, inclusive. If a minus character is required in a + class, it must be escaped with a backslash or appear in a position + where it cannot be interpreted as indicating a range, typically as the + first or last character in the class, or immediately after a range. For + example, [b-d-z] matches letters in the range b to d, a hyphen charac- + ter, or z. It is not possible to have the literal character "]" as the end charac- - ter of a range. A pattern such as [W-]46] is interpreted as a class of - two characters ("W" and "-") followed by a literal string "46]", so it - would match "W46]" or "-46]". However, if the "]" is escaped with a - backslash it is interpreted as the end of range, so [W-\]46] is inter- - preted as a class containing a range followed by two other characters. - The octal or hexadecimal representation of "]" can also be used to end + ter of a range. A pattern such as [W-]46] is interpreted as a class of + two characters ("W" and "-") followed by a literal string "46]", so it + would match "W46]" or "-46]". However, if the "]" is escaped with a + backslash it is interpreted as the end of range, so [W-\]46] is inter- + preted as a class containing a range followed by two other characters. + The octal or hexadecimal representation of "]" can also be used to end a range. + An error is generated if a POSIX character class (see below) or an + escape sequence other than one that defines a single character appears + at a point where a range ending character is expected. For example, + [z-\xff] is valid, but [A-\d] and [A-[:digit:]] are not. + Ranges operate in the collating sequence of character values. They can also be used for characters specified numerically, for example [\000-\037]. Ranges can include any characters that are valid for the @@ -5700,15 +5830,17 @@ POSIX CHARACTER CLASSES lower lower case letters print printing characters, including space punct printing characters, excluding letters and digits and space - space white space (not quite the same as \s) + space white space (the same as \s from PCRE 8.34) upper upper case letters word "word" characters (same as \w) xdigit hexadecimal digits - The "space" characters are HT (9), LF (10), VT (11), FF (12), CR (13), - and space (32). Notice that this list includes the VT character (code - 11). This makes "space" different to \s, which does not include VT (for - Perl compatibility). + The default "space" characters are HT (9), LF (10), VT (11), FF (12), + CR (13), and space (32). If locale-specific matching is taking place, + there may be additional space characters. "Space" used to be different + to \s, which did not include VT, for Perl compatibility. However, Perl + changed at release 5.18, and PCRE followed at release 8.34. "Space" and + \s now match the same set of characters. The name "word" is a Perl extension, and "blank" is a GNU extension from Perl 5.8. Another Perl extension is negation, which is indicated @@ -5720,11 +5852,11 @@ POSIX CHARACTER CLASSES POSIX syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not supported, and an error is given if they are encountered. - By default, in UTF modes, characters with values greater than 128 do - not match any of the POSIX character classes. However, if the PCRE_UCP - option is passed to pcre_compile(), some of the classes are changed so - that Unicode character properties are used. This is achieved by replac- - ing the POSIX classes by other sequences, as follows: + By default, characters with values greater than 128 do not match any of + the POSIX character classes. However, if the PCRE_UCP option is passed + to pcre_compile(), some of the classes are changed so that Unicode + character properties are used. This is achieved by replacing certain + POSIX classes by other sequences, as follows: [:alnum:] becomes \p{Xan} [:alpha:] becomes \p{L} @@ -5735,9 +5867,28 @@ POSIX CHARACTER CLASSES [:upper:] becomes \p{Lu} [:word:] becomes \p{Xwd} - Negated versions, such as [:^alpha:] use \P instead of \p. The other - POSIX classes are unchanged, and match only characters with code points - less than 128. + Negated versions, such as [:^alpha:] use \P instead of \p. Three other + POSIX classes are handled specially in UCP mode: + + [:graph:] This matches characters that have glyphs that mark the page + when printed. In Unicode property terms, it matches all char- + acters with the L, M, N, P, S, or Cf properties, except for: + + U+061C Arabic Letter Mark + U+180E Mongolian Vowel Separator + U+2066 - U+2069 Various "isolate"s + + + [:print:] This matches the same characters as [:graph:] plus space + characters that are not controls, that is, characters with + the Zs property. + + [:punct:] This matches all characters that have the Unicode P (punctua- + tion) property, plus those characters whose code points are + less than 128 that have the S (Symbol) property. + + The other POSIX classes are unchanged, and match only characters with + code points less than 128. VERTICAL BAR @@ -5934,12 +6085,12 @@ NAMED SUBPATTERNS references, recursion, and conditions, can be made by name as well as by number. - Names consist of up to 32 alphanumeric characters and underscores. - Named capturing parentheses are still allocated numbers as well as - names, exactly as if the names were not present. The PCRE API provides - function calls for extracting the name-to-number translation table from - a compiled pattern. There is also a convenience function for extracting - a captured substring by name. + Names consist of up to 32 alphanumeric characters and underscores, but + must start with a non-digit. Named capturing parentheses are still + allocated numbers as well as names, exactly as if the names were not + present. The PCRE API provides function calls for extracting the name- + to-number translation table from a compiled pattern. There is also a + convenience function for extracting a captured substring by name. By default, a name must be unique within a pattern, but it is possible to relax this constraint by setting the PCRE_DUPNAMES option at compile @@ -5967,28 +6118,38 @@ NAMED SUBPATTERNS subpattern it was. If you make a back reference to a non-unique named subpattern from - elsewhere in the pattern, the one that corresponds to the first occur- - rence of the name is used. In the absence of duplicate numbers (see the - previous section) this is the one with the lowest number. If you use a - named reference in a condition test (see the section about conditions - below), either to check whether a subpattern has matched, or to check - for recursion, all subpatterns with the same name are tested. If the - condition is true for any one of them, the overall condition is true. - This is the same behaviour as testing by number. For further details of - the interfaces for handling named subpatterns, see the pcreapi documen- - tation. + elsewhere in the pattern, the subpatterns to which the name refers are + checked in the order in which they appear in the overall pattern. The + first one that is set is used for the reference. For example, this pat- + tern matches both "foofoo" and "barbar" but not "foobar" or "barfoo": + + (?:(?<n>foo)|(?<n>bar))\k<n> + + + If you make a subroutine call to a non-unique named subpattern, the one + that corresponds to the first occurrence of the name is used. In the + absence of duplicate numbers (see the previous section) this is the one + with the lowest number. + + If you use a named reference in a condition test (see the section about + conditions below), either to check whether a subpattern has matched, or + to check for recursion, all subpatterns with the same name are tested. + If the condition is true for any one of them, the overall condition is + true. This is the same behaviour as testing by number. For further + details of the interfaces for handling named subpatterns, see the + pcreapi documentation. Warning: You cannot use different names to distinguish between two sub- - patterns with the same number because PCRE uses only the numbers when + patterns with the same number because PCRE uses only the numbers when matching. For this reason, an error is given at compile time if differ- - ent names are given to subpatterns with the same number. However, you - can give the same name to subpatterns with the same number, even when - PCRE_DUPNAMES is not set. + ent names are given to subpatterns with the same number. However, you + can always give the same name to subpatterns with the same number, even + when PCRE_DUPNAMES is not set. REPETITION - Repetition is specified by quantifiers, which can follow any of the + Repetition is specified by quantifiers, which can follow any of the following items: a literal data character @@ -6002,17 +6163,17 @@ REPETITION a parenthesized subpattern (including assertions) a subroutine call to a subpattern (recursive or otherwise) - The general repetition quantifier specifies a minimum and maximum num- - ber of permitted matches, by giving the two numbers in curly brackets - (braces), separated by a comma. The numbers must be less than 65536, + The general repetition quantifier specifies a minimum and maximum num- + ber of permitted matches, by giving the two numbers in curly brackets + (braces), separated by a comma. The numbers must be less than 65536, and the first must be less than or equal to the second. For example: z{2,4} - matches "zz", "zzz", or "zzzz". A closing brace on its own is not a - special character. If the second number is omitted, but the comma is - present, there is no upper limit; if the second number and the comma - are both omitted, the quantifier specifies an exact number of required + matches "zz", "zzz", or "zzzz". A closing brace on its own is not a + special character. If the second number is omitted, but the comma is + present, there is no upper limit; if the second number and the comma + are both omitted, the quantifier specifies an exact number of required matches. Thus [aeiou]{3,} @@ -6021,50 +6182,50 @@ REPETITION \d{8} - matches exactly 8 digits. An opening curly bracket that appears in a - position where a quantifier is not allowed, or one that does not match - the syntax of a quantifier, is taken as a literal character. For exam- + matches exactly 8 digits. An opening curly bracket that appears in a + position where a quantifier is not allowed, or one that does not match + the syntax of a quantifier, is taken as a literal character. For exam- ple, {,6} is not a quantifier, but a literal string of four characters. In UTF modes, quantifiers apply to characters rather than to individual - data units. Thus, for example, \x{100}{2} matches two characters, each + data units. Thus, for example, \x{100}{2} matches two characters, each of which is represented by a two-byte sequence in a UTF-8 string. Simi- - larly, \X{3} matches three Unicode extended grapheme clusters, each of - which may be several data units long (and they may be of different + larly, \X{3} matches three Unicode extended grapheme clusters, each of + which may be several data units long (and they may be of different lengths). The quantifier {0} is permitted, causing the expression to behave as if the previous item and the quantifier were not present. This may be use- - ful for subpatterns that are referenced as subroutines from elsewhere + ful for subpatterns that are referenced as subroutines from elsewhere in the pattern (but see also the section entitled "Defining subpatterns - for use by reference only" below). Items other than subpatterns that + for use by reference only" below). Items other than subpatterns that have a {0} quantifier are omitted from the compiled pattern. - For convenience, the three most common quantifiers have single-charac- + For convenience, the three most common quantifiers have single-charac- ter abbreviations: * is equivalent to {0,} + is equivalent to {1,} ? is equivalent to {0,1} - It is possible to construct infinite loops by following a subpattern + It is possible to construct infinite loops by following a subpattern that can match no characters with a quantifier that has no upper limit, for example: (a?)* Earlier versions of Perl and PCRE used to give an error at compile time - for such patterns. However, because there are cases where this can be - useful, such patterns are now accepted, but if any repetition of the - subpattern does in fact match no characters, the loop is forcibly bro- + for such patterns. However, because there are cases where this can be + useful, such patterns are now accepted, but if any repetition of the + subpattern does in fact match no characters, the loop is forcibly bro- ken. - By default, the quantifiers are "greedy", that is, they match as much - as possible (up to the maximum number of permitted times), without - causing the rest of the pattern to fail. The classic example of where + By default, the quantifiers are "greedy", that is, they match as much + as possible (up to the maximum number of permitted times), without + causing the rest of the pattern to fail. The classic example of where this gives problems is in trying to match comments in C programs. These - appear between /* and */ and within the comment, individual * and / - characters may appear. An attempt to match C comments by applying the + appear between /* and */ and within the comment, individual * and / + characters may appear. An attempt to match C comments by applying the pattern /\*.*\*/ @@ -6073,19 +6234,19 @@ REPETITION /* first comment */ not comment /* second comment */ - fails, because it matches the entire string owing to the greediness of + fails, because it matches the entire string owing to the greediness of the .* item. - However, if a quantifier is followed by a question mark, it ceases to + However, if a quantifier is followed by a question mark, it ceases to be greedy, and instead matches the minimum number of times possible, so the pattern /\*.*?\*/ - does the right thing with the C comments. The meaning of the various - quantifiers is not otherwise changed, just the preferred number of - matches. Do not confuse this use of question mark with its use as a - quantifier in its own right. Because it has two uses, it can sometimes + does the right thing with the C comments. The meaning of the various + quantifiers is not otherwise changed, just the preferred number of + matches. Do not confuse this use of question mark with its use as a + quantifier in its own right. Because it has two uses, it can sometimes appear doubled, as in \d??\d @@ -6093,45 +6254,45 @@ REPETITION which matches one digit by preference, but can match two if that is the only way the rest of the pattern matches. - If the PCRE_UNGREEDY option is set (an option that is not available in - Perl), the quantifiers are not greedy by default, but individual ones - can be made greedy by following them with a question mark. In other + If the PCRE_UNGREEDY option is set (an option that is not available in + Perl), the quantifiers are not greedy by default, but individual ones + can be made greedy by following them with a question mark. In other words, it inverts the default behaviour. - When a parenthesized subpattern is quantified with a minimum repeat - count that is greater than 1 or with a limited maximum, more memory is - required for the compiled pattern, in proportion to the size of the + When a parenthesized subpattern is quantified with a minimum repeat + count that is greater than 1 or with a limited maximum, more memory is + required for the compiled pattern, in proportion to the size of the minimum or maximum. If a pattern starts with .* or .{0,} and the PCRE_DOTALL option (equiv- - alent to Perl's /s) is set, thus allowing the dot to match newlines, - the pattern is implicitly anchored, because whatever follows will be - tried against every character position in the subject string, so there - is no point in retrying the overall match at any position after the - first. PCRE normally treats such a pattern as though it were preceded + alent to Perl's /s) is set, thus allowing the dot to match newlines, + the pattern is implicitly anchored, because whatever follows will be + tried against every character position in the subject string, so there + is no point in retrying the overall match at any position after the + first. PCRE normally treats such a pattern as though it were preceded by \A. - In cases where it is known that the subject string contains no new- - lines, it is worth setting PCRE_DOTALL in order to obtain this opti- + In cases where it is known that the subject string contains no new- + lines, it is worth setting PCRE_DOTALL in order to obtain this opti- mization, or alternatively using ^ to indicate anchoring explicitly. - However, there are some cases where the optimization cannot be used. + However, there are some cases where the optimization cannot be used. When .* is inside capturing parentheses that are the subject of a back reference elsewhere in the pattern, a match at the start may fail where a later one succeeds. Consider, for example: (.*)abc\1 - If the subject is "xyz123abc123" the match point is the fourth charac- + If the subject is "xyz123abc123" the match point is the fourth charac- ter. For this reason, such a pattern is not implicitly anchored. - Another case where implicit anchoring is not applied is when the lead- - ing .* is inside an atomic group. Once again, a match at the start may + Another case where implicit anchoring is not applied is when the lead- + ing .* is inside an atomic group. Once again, a match at the start may fail where a later one succeeds. Consider this pattern: (?>.*?a)b - It matches "ab" in the subject "aab". The use of the backtracking con- + It matches "ab" in the subject "aab". The use of the backtracking con- trol verbs (*PRUNE) and (*SKIP) also disable this optimization. When a capturing subpattern is repeated, the value captured is the sub- @@ -6140,8 +6301,8 @@ REPETITION (tweedle[dume]{3}\s*)+ has matched "tweedledum tweedledee" the value of the captured substring - is "tweedledee". However, if there are nested capturing subpatterns, - the corresponding captured values may have been set in previous itera- + is "tweedledee". However, if there are nested capturing subpatterns, + the corresponding captured values may have been set in previous itera- tions. For example, after /(a|(b))+/ @@ -6151,53 +6312,53 @@ REPETITION ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS - With both maximizing ("greedy") and minimizing ("ungreedy" or "lazy") - repetition, failure of what follows normally causes the repeated item - to be re-evaluated to see if a different number of repeats allows the - rest of the pattern to match. Sometimes it is useful to prevent this, - either to change the nature of the match, or to cause it fail earlier - than it otherwise might, when the author of the pattern knows there is + With both maximizing ("greedy") and minimizing ("ungreedy" or "lazy") + repetition, failure of what follows normally causes the repeated item + to be re-evaluated to see if a different number of repeats allows the + rest of the pattern to match. Sometimes it is useful to prevent this, + either to change the nature of the match, or to cause it fail earlier + than it otherwise might, when the author of the pattern knows there is no point in carrying on. - Consider, for example, the pattern \d+foo when applied to the subject + Consider, for example, the pattern \d+foo when applied to the subject line 123456bar After matching all 6 digits and then failing to match "foo", the normal - action of the matcher is to try again with only 5 digits matching the - \d+ item, and then with 4, and so on, before ultimately failing. - "Atomic grouping" (a term taken from Jeffrey Friedl's book) provides - the means for specifying that once a subpattern has matched, it is not + action of the matcher is to try again with only 5 digits matching the + \d+ item, and then with 4, and so on, before ultimately failing. + "Atomic grouping" (a term taken from Jeffrey Friedl's book) provides + the means for specifying that once a subpattern has matched, it is not to be re-evaluated in this way. - If we use atomic grouping for the previous example, the matcher gives - up immediately on failing to match "foo" the first time. The notation + If we use atomic grouping for the previous example, the matcher gives + up immediately on failing to match "foo" the first time. The notation is a kind of special parenthesis, starting with (?> as in this example: (?>\d+)foo - This kind of parenthesis "locks up" the part of the pattern it con- - tains once it has matched, and a failure further into the pattern is - prevented from backtracking into it. Backtracking past it to previous + This kind of parenthesis "locks up" the part of the pattern it con- + tains once it has matched, and a failure further into the pattern is + prevented from backtracking into it. Backtracking past it to previous items, however, works as normal. - An alternative description is that a subpattern of this type matches - the string of characters that an identical standalone pattern would + An alternative description is that a subpattern of this type matches + the string of characters that an identical standalone pattern would match, if anchored at the current point in the subject string. Atomic grouping subpatterns are not capturing subpatterns. Simple cases such as the above example can be thought of as a maximizing repeat that - must swallow everything it can. So, while both \d+ and \d+? are pre- - pared to adjust the number of digits they match in order to make the + must swallow everything it can. So, while both \d+ and \d+? are pre- + pared to adjust the number of digits they match in order to make the rest of the pattern match, (?>\d+) can only match an entire sequence of digits. - Atomic groups in general can of course contain arbitrarily complicated - subpatterns, and can be nested. However, when the subpattern for an + Atomic groups in general can of course contain arbitrarily complicated + subpatterns, and can be nested. However, when the subpattern for an atomic group is just a single repeated item, as in the example above, a - simpler notation, called a "possessive quantifier" can be used. This - consists of an additional + character following a quantifier. Using + simpler notation, called a "possessive quantifier" can be used. This + consists of an additional + character following a quantifier. Using this notation, the previous example can be rewritten as \d++foo @@ -6207,45 +6368,45 @@ ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS (abc|xyz){2,3}+ - Possessive quantifiers are always greedy; the setting of the + Possessive quantifiers are always greedy; the setting of the PCRE_UNGREEDY option is ignored. They are a convenient notation for the - simpler forms of atomic group. However, there is no difference in the - meaning of a possessive quantifier and the equivalent atomic group, - though there may be a performance difference; possessive quantifiers + simpler forms of atomic group. However, there is no difference in the + meaning of a possessive quantifier and the equivalent atomic group, + though there may be a performance difference; possessive quantifiers should be slightly faster. - The possessive quantifier syntax is an extension to the Perl 5.8 syn- - tax. Jeffrey Friedl originated the idea (and the name) in the first + The possessive quantifier syntax is an extension to the Perl 5.8 syn- + tax. Jeffrey Friedl originated the idea (and the name) in the first edition of his book. Mike McCloskey liked it, so implemented it when he - built Sun's Java package, and PCRE copied it from there. It ultimately + built Sun's Java package, and PCRE copied it from there. It ultimately found its way into Perl at release 5.10. PCRE has an optimization that automatically "possessifies" certain sim- - ple pattern constructs. For example, the sequence A+B is treated as - A++B because there is no point in backtracking into a sequence of A's + ple pattern constructs. For example, the sequence A+B is treated as + A++B because there is no point in backtracking into a sequence of A's when B must follow. - When a pattern contains an unlimited repeat inside a subpattern that - can itself be repeated an unlimited number of times, the use of an - atomic group is the only way to avoid some failing matches taking a + When a pattern contains an unlimited repeat inside a subpattern that + can itself be repeated an unlimited number of times, the use of an + atomic group is the only way to avoid some failing matches taking a very long time indeed. The pattern (\D+|<\d+>)*[!?] - matches an unlimited number of substrings that either consist of non- - digits, or digits enclosed in <>, followed by either ! or ?. When it + matches an unlimited number of substrings that either consist of non- + digits, or digits enclosed in <>, followed by either ! or ?. When it matches, it runs quickly. However, if it is applied to aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa - it takes a long time before reporting failure. This is because the - string can be divided between the internal \D+ repeat and the external - * repeat in a large number of ways, and all have to be tried. (The - example uses [!?] rather than a single character at the end, because - both PCRE and Perl have an optimization that allows for fast failure - when a single character is used. They remember the last single charac- - ter that is required for a match, and fail early if it is not present - in the string.) If the pattern is changed so that it uses an atomic + it takes a long time before reporting failure. This is because the + string can be divided between the internal \D+ repeat and the external + * repeat in a large number of ways, and all have to be tried. (The + example uses [!?] rather than a single character at the end, because + both PCRE and Perl have an optimization that allows for fast failure + when a single character is used. They remember the last single charac- + ter that is required for a match, and fail early if it is not present + in the string.) If the pattern is changed so that it uses an atomic group, like this: ((?>\D+)|<\d+>)*[!?] @@ -6257,28 +6418,28 @@ BACK REFERENCES Outside a character class, a backslash followed by a digit greater than 0 (and possibly further digits) is a back reference to a capturing sub- - pattern earlier (that is, to its left) in the pattern, provided there + pattern earlier (that is, to its left) in the pattern, provided there have been that many previous capturing left parentheses. However, if the decimal number following the backslash is less than 10, - it is always taken as a back reference, and causes an error only if - there are not that many capturing left parentheses in the entire pat- - tern. In other words, the parentheses that are referenced need not be - to the left of the reference for numbers less than 10. A "forward back - reference" of this type can make sense when a repetition is involved - and the subpattern to the right has participated in an earlier itera- + it is always taken as a back reference, and causes an error only if + there are not that many capturing left parentheses in the entire pat- + tern. In other words, the parentheses that are referenced need not be + to the left of the reference for numbers less than 10. A "forward back + reference" of this type can make sense when a repetition is involved + and the subpattern to the right has participated in an earlier itera- tion. - It is not possible to have a numerical "forward back reference" to a - subpattern whose number is 10 or more using this syntax because a - sequence such as \50 is interpreted as a character defined in octal. + It is not possible to have a numerical "forward back reference" to a + subpattern whose number is 10 or more using this syntax because a + sequence such as \50 is interpreted as a character defined in octal. See the subsection entitled "Non-printing characters" above for further - details of the handling of digits following a backslash. There is no - such problem when named parentheses are used. A back reference to any + details of the handling of digits following a backslash. There is no + such problem when named parentheses are used. A back reference to any subpattern is possible using named parentheses (see below). - Another way of avoiding the ambiguity inherent in the use of digits - following a backslash is to use the \g escape sequence. This escape + Another way of avoiding the ambiguity inherent in the use of digits + following a backslash is to use the \g escape sequence. This escape must be followed by an unsigned number or a negative number, optionally enclosed in braces. These examples are all identical: @@ -6286,7 +6447,7 @@ BACK REFERENCES (ring), \g1 (ring), \g{1} - An unsigned number specifies an absolute reference without the ambigu- + An unsigned number specifies an absolute reference without the ambigu- ity that is present in the older syntax. It is also useful when literal digits follow the reference. A negative number is a relative reference. Consider this example: @@ -6295,33 +6456,33 @@ BACK REFERENCES The sequence \g{-1} is a reference to the most recently started captur- ing subpattern before \g, that is, is it equivalent to \2 in this exam- - ple. Similarly, \g{-2} would be equivalent to \1. The use of relative - references can be helpful in long patterns, and also in patterns that - are created by joining together fragments that contain references + ple. Similarly, \g{-2} would be equivalent to \1. The use of relative + references can be helpful in long patterns, and also in patterns that + are created by joining together fragments that contain references within themselves. - A back reference matches whatever actually matched the capturing sub- - pattern in the current subject string, rather than anything matching + A back reference matches whatever actually matched the capturing sub- + pattern in the current subject string, rather than anything matching the subpattern itself (see "Subpatterns as subroutines" below for a way of doing that). So the pattern (sens|respons)e and \1ibility - matches "sense and sensibility" and "response and responsibility", but - not "sense and responsibility". If caseful matching is in force at the - time of the back reference, the case of letters is relevant. For exam- + matches "sense and sensibility" and "response and responsibility", but + not "sense and responsibility". If caseful matching is in force at the + time of the back reference, the case of letters is relevant. For exam- ple, ((?i)rah)\s+\1 - matches "rah rah" and "RAH RAH", but not "RAH rah", even though the + matches "rah rah" and "RAH RAH", but not "RAH rah", even though the original capturing subpattern is matched caselessly. - There are several different ways of writing back references to named - subpatterns. The .NET syntax \k{name} and the Perl syntax \k<name> or - \k'name' are supported, as is the Python syntax (?P=name). Perl 5.10's + There are several different ways of writing back references to named + subpatterns. The .NET syntax \k{name} and the Perl syntax \k<name> or + \k'name' are supported, as is the Python syntax (?P=name). Perl 5.10's unified back reference syntax, in which \g can be used for both numeric - and named references, is also supported. We could rewrite the above + and named references, is also supported. We could rewrite the above example in any of the following ways: (?<p1>(?i)rah)\s+\k<p1> @@ -6329,84 +6490,84 @@ BACK REFERENCES (?P<p1>(?i)rah)\s+(?P=p1) (?<p1>(?i)rah)\s+\g{p1} - A subpattern that is referenced by name may appear in the pattern + A subpattern that is referenced by name may appear in the pattern before or after the reference. - There may be more than one back reference to the same subpattern. If a - subpattern has not actually been used in a particular match, any back + There may be more than one back reference to the same subpattern. If a + subpattern has not actually been used in a particular match, any back references to it always fail by default. For example, the pattern (a|(bc))\2 - always fails if it starts to match "a" rather than "bc". However, if + always fails if it starts to match "a" rather than "bc". However, if the PCRE_JAVASCRIPT_COMPAT option is set at compile time, a back refer- ence to an unset value matches an empty string. - Because there may be many capturing parentheses in a pattern, all dig- - its following a backslash are taken as part of a potential back refer- - ence number. If the pattern continues with a digit character, some - delimiter must be used to terminate the back reference. If the - PCRE_EXTENDED option is set, this can be white space. Otherwise, the + Because there may be many capturing parentheses in a pattern, all dig- + its following a backslash are taken as part of a potential back refer- + ence number. If the pattern continues with a digit character, some + delimiter must be used to terminate the back reference. If the + PCRE_EXTENDED option is set, this can be white space. Otherwise, the \g{ syntax or an empty comment (see "Comments" below) can be used. Recursive back references - A back reference that occurs inside the parentheses to which it refers - fails when the subpattern is first used, so, for example, (a\1) never - matches. However, such references can be useful inside repeated sub- + A back reference that occurs inside the parentheses to which it refers + fails when the subpattern is first used, so, for example, (a\1) never + matches. However, such references can be useful inside repeated sub- patterns. For example, the pattern (a|b\1)+ matches any number of "a"s and also "aba", "ababbaa" etc. At each iter- - ation of the subpattern, the back reference matches the character - string corresponding to the previous iteration. In order for this to - work, the pattern must be such that the first iteration does not need - to match the back reference. This can be done using alternation, as in + ation of the subpattern, the back reference matches the character + string corresponding to the previous iteration. In order for this to + work, the pattern must be such that the first iteration does not need + to match the back reference. This can be done using alternation, as in the example above, or by a quantifier with a minimum of zero. - Back references of this type cause the group that they reference to be - treated as an atomic group. Once the whole group has been matched, a - subsequent matching failure cannot cause backtracking into the middle + Back references of this type cause the group that they reference to be + treated as an atomic group. Once the whole group has been matched, a + subsequent matching failure cannot cause backtracking into the middle of the group. ASSERTIONS - An assertion is a test on the characters following or preceding the - current matching point that does not actually consume any characters. - The simple assertions coded as \b, \B, \A, \G, \Z, \z, ^ and $ are + An assertion is a test on the characters following or preceding the + current matching point that does not actually consume any characters. + The simple assertions coded as \b, \B, \A, \G, \Z, \z, ^ and $ are described above. - More complicated assertions are coded as subpatterns. There are two - kinds: those that look ahead of the current position in the subject - string, and those that look behind it. An assertion subpattern is - matched in the normal way, except that it does not cause the current + More complicated assertions are coded as subpatterns. There are two + kinds: those that look ahead of the current position in the subject + string, and those that look behind it. An assertion subpattern is + matched in the normal way, except that it does not cause the current matching position to be changed. - Assertion subpatterns are not capturing subpatterns. If such an asser- - tion contains capturing subpatterns within it, these are counted for - the purposes of numbering the capturing subpatterns in the whole pat- - tern. However, substring capturing is carried out only for positive + Assertion subpatterns are not capturing subpatterns. If such an asser- + tion contains capturing subpatterns within it, these are counted for + the purposes of numbering the capturing subpatterns in the whole pat- + tern. However, substring capturing is carried out only for positive assertions. (Perl sometimes, but not always, does do capturing in nega- tive assertions.) - For compatibility with Perl, assertion subpatterns may be repeated; - though it makes no sense to assert the same thing several times, the - side effect of capturing parentheses may occasionally be useful. In + For compatibility with Perl, assertion subpatterns may be repeated; + though it makes no sense to assert the same thing several times, the + side effect of capturing parentheses may occasionally be useful. In practice, there only three cases: - (1) If the quantifier is {0}, the assertion is never obeyed during - matching. However, it may contain internal capturing parenthesized + (1) If the quantifier is {0}, the assertion is never obeyed during + matching. However, it may contain internal capturing parenthesized groups that are called from elsewhere via the subroutine mechanism. - (2) If quantifier is {0,n} where n is greater than zero, it is treated - as if it were {0,1}. At run time, the rest of the pattern match is + (2) If quantifier is {0,n} where n is greater than zero, it is treated + as if it were {0,1}. At run time, the rest of the pattern match is tried with and without the assertion, the order depending on the greed- iness of the quantifier. - (3) If the minimum repetition is greater than zero, the quantifier is - ignored. The assertion is obeyed just once when encountered during + (3) If the minimum repetition is greater than zero, the quantifier is + ignored. The assertion is obeyed just once when encountered during matching. Lookahead assertions @@ -6416,38 +6577,38 @@ ASSERTIONS \w+(?=;) - matches a word followed by a semicolon, but does not include the semi- + matches a word followed by a semicolon, but does not include the semi- colon in the match, and foo(?!bar) - matches any occurrence of "foo" that is not followed by "bar". Note + matches any occurrence of "foo" that is not followed by "bar". Note that the apparently similar pattern (?!foo)bar - does not find an occurrence of "bar" that is preceded by something - other than "foo"; it finds any occurrence of "bar" whatsoever, because + does not find an occurrence of "bar" that is preceded by something + other than "foo"; it finds any occurrence of "bar" whatsoever, because the assertion (?!foo) is always true when the next three characters are "bar". A lookbehind assertion is needed to achieve the other effect. If you want to force a matching failure at some point in a pattern, the - most convenient way to do it is with (?!) because an empty string - always matches, so an assertion that requires there not to be an empty + most convenient way to do it is with (?!) because an empty string + always matches, so an assertion that requires there not to be an empty string must always fail. The backtracking control verb (*FAIL) or (*F) is a synonym for (?!). Lookbehind assertions - Lookbehind assertions start with (?<= for positive assertions and (?<! + Lookbehind assertions start with (?<= for positive assertions and (?<! for negative assertions. For example, (?<!foo)bar - does find an occurrence of "bar" that is not preceded by "foo". The - contents of a lookbehind assertion are restricted such that all the + does find an occurrence of "bar" that is not preceded by "foo". The + contents of a lookbehind assertion are restricted such that all the strings it matches must have a fixed length. However, if there are sev- - eral top-level alternatives, they do not all have to have the same + eral top-level alternatives, they do not all have to have the same fixed length. Thus (?<=bullock|donkey) @@ -6456,62 +6617,62 @@ ASSERTIONS (?<!dogs?|cats?) - causes an error at compile time. Branches that match different length - strings are permitted only at the top level of a lookbehind assertion. + causes an error at compile time. Branches that match different length + strings are permitted only at the top level of a lookbehind assertion. This is an extension compared with Perl, which requires all branches to match the same length of string. An assertion such as (?<=ab(c|de)) - is not permitted, because its single top-level branch can match two + is not permitted, because its single top-level branch can match two different lengths, but it is acceptable to PCRE if rewritten to use two top-level branches: (?<=abc|abde) - In some cases, the escape sequence \K (see above) can be used instead + In some cases, the escape sequence \K (see above) can be used instead of a lookbehind assertion to get round the fixed-length restriction. - The implementation of lookbehind assertions is, for each alternative, - to temporarily move the current position back by the fixed length and + The implementation of lookbehind assertions is, for each alternative, + to temporarily move the current position back by the fixed length and then try to match. If there are insufficient characters before the cur- rent position, the assertion fails. - In a UTF mode, PCRE does not allow the \C escape (which matches a sin- - gle data unit even in a UTF mode) to appear in lookbehind assertions, - because it makes it impossible to calculate the length of the lookbe- - hind. The \X and \R escapes, which can match different numbers of data + In a UTF mode, PCRE does not allow the \C escape (which matches a sin- + gle data unit even in a UTF mode) to appear in lookbehind assertions, + because it makes it impossible to calculate the length of the lookbe- + hind. The \X and \R escapes, which can match different numbers of data units, are also not permitted. - "Subroutine" calls (see below) such as (?2) or (?&X) are permitted in - lookbehinds, as long as the subpattern matches a fixed-length string. + "Subroutine" calls (see below) such as (?2) or (?&X) are permitted in + lookbehinds, as long as the subpattern matches a fixed-length string. Recursion, however, is not supported. - Possessive quantifiers can be used in conjunction with lookbehind + Possessive quantifiers can be used in conjunction with lookbehind assertions to specify efficient matching of fixed-length strings at the end of subject strings. Consider a simple pattern such as abcd$ - when applied to a long string that does not match. Because matching + when applied to a long string that does not match. Because matching proceeds from left to right, PCRE will look for each "a" in the subject - and then see if what follows matches the rest of the pattern. If the + and then see if what follows matches the rest of the pattern. If the pattern is specified as ^.*abcd$ - the initial .* matches the entire string at first, but when this fails + the initial .* matches the entire string at first, but when this fails (because there is no following "a"), it backtracks to match all but the - last character, then all but the last two characters, and so on. Once - again the search for "a" covers the entire string, from right to left, + last character, then all but the last two characters, and so on. Once + again the search for "a" covers the entire string, from right to left, so we are no better off. However, if the pattern is written as ^.*+(?<=abcd) - there can be no backtracking for the .*+ item; it can match only the - entire string. The subsequent lookbehind assertion does a single test - on the last four characters. If it fails, the match fails immediately. - For long strings, this approach makes a significant difference to the + there can be no backtracking for the .*+ item; it can match only the + entire string. The subsequent lookbehind assertion does a single test + on the last four characters. If it fails, the match fails immediately. + For long strings, this approach makes a significant difference to the processing time. Using multiple assertions @@ -6520,18 +6681,18 @@ ASSERTIONS (?<=\d{3})(?<!999)foo - matches "foo" preceded by three digits that are not "999". Notice that - each of the assertions is applied independently at the same point in - the subject string. First there is a check that the previous three - characters are all digits, and then there is a check that the same + matches "foo" preceded by three digits that are not "999". Notice that + each of the assertions is applied independently at the same point in + the subject string. First there is a check that the previous three + characters are all digits, and then there is a check that the same three characters are not "999". This pattern does not match "foo" pre- - ceded by six characters, the first of which are digits and the last - three of which are not "999". For example, it doesn't match "123abc- + ceded by six characters, the first of which are digits and the last + three of which are not "999". For example, it doesn't match "123abc- foo". A pattern to do that is (?<=\d{3}...)(?<!999)foo - This time the first assertion looks at the preceding six characters, + This time the first assertion looks at the preceding six characters, checking that the first three are digits, and then the second assertion checks that the preceding three characters are not "999". @@ -6539,29 +6700,29 @@ ASSERTIONS (?<=(?<!foo)bar)baz - matches an occurrence of "baz" that is preceded by "bar" which in turn + matches an occurrence of "baz" that is preceded by "bar" which in turn is not preceded by "foo", while (?<=\d{3}(?!999)...)foo - is another pattern that matches "foo" preceded by three digits and any + is another pattern that matches "foo" preceded by three digits and any three characters that are not "999". CONDITIONAL SUBPATTERNS - It is possible to cause the matching process to obey a subpattern con- - ditionally or to choose between two alternative subpatterns, depending - on the result of an assertion, or whether a specific capturing subpat- - tern has already been matched. The two possible forms of conditional + It is possible to cause the matching process to obey a subpattern con- + ditionally or to choose between two alternative subpatterns, depending + on the result of an assertion, or whether a specific capturing subpat- + tern has already been matched. The two possible forms of conditional subpattern are: (?(condition)yes-pattern) (?(condition)yes-pattern|no-pattern) - If the condition is satisfied, the yes-pattern is used; otherwise the - no-pattern (if present) is used. If there are more than two alterna- - tives in the subpattern, a compile-time error occurs. Each of the two + If the condition is satisfied, the yes-pattern is used; otherwise the + no-pattern (if present) is used. If there are more than two alterna- + tives in the subpattern, a compile-time error occurs. Each of the two alternatives may itself contain nested subpatterns of any form, includ- ing conditional subpatterns; the restriction to two alternatives applies only at the level of the condition. This pattern fragment is an @@ -6570,60 +6731,55 @@ CONDITIONAL SUBPATTERNS (?(1) (A|B|C) | (D | (?(2)E|F) | E) ) - There are four kinds of condition: references to subpatterns, refer- + There are four kinds of condition: references to subpatterns, refer- ences to recursion, a pseudo-condition called DEFINE, and assertions. Checking for a used subpattern by number - If the text between the parentheses consists of a sequence of digits, + If the text between the parentheses consists of a sequence of digits, the condition is true if a capturing subpattern of that number has pre- - viously matched. If there is more than one capturing subpattern with - the same number (see the earlier section about duplicate subpattern - numbers), the condition is true if any of them have matched. An alter- - native notation is to precede the digits with a plus or minus sign. In - this case, the subpattern number is relative rather than absolute. The - most recently opened parentheses can be referenced by (?(-1), the next - most recent by (?(-2), and so on. Inside loops it can also make sense + viously matched. If there is more than one capturing subpattern with + the same number (see the earlier section about duplicate subpattern + numbers), the condition is true if any of them have matched. An alter- + native notation is to precede the digits with a plus or minus sign. In + this case, the subpattern number is relative rather than absolute. The + most recently opened parentheses can be referenced by (?(-1), the next + most recent by (?(-2), and so on. Inside loops it can also make sense to refer to subsequent groups. The next parentheses to be opened can be - referenced as (?(+1), and so on. (The value zero in any of these forms + referenced as (?(+1), and so on. (The value zero in any of these forms is not used; it provokes a compile-time error.) - Consider the following pattern, which contains non-significant white + Consider the following pattern, which contains non-significant white space to make it more readable (assume the PCRE_EXTENDED option) and to divide it into three parts for ease of discussion: ( \( )? [^()]+ (?(1) \) ) - The first part matches an optional opening parenthesis, and if that + The first part matches an optional opening parenthesis, and if that character is present, sets it as the first captured substring. The sec- - ond part matches one or more characters that are not parentheses. The - third part is a conditional subpattern that tests whether or not the - first set of parentheses matched. If they did, that is, if subject - started with an opening parenthesis, the condition is true, and so the - yes-pattern is executed and a closing parenthesis is required. Other- - wise, since no-pattern is not present, the subpattern matches nothing. - In other words, this pattern matches a sequence of non-parentheses, + ond part matches one or more characters that are not parentheses. The + third part is a conditional subpattern that tests whether or not the + first set of parentheses matched. If they did, that is, if subject + started with an opening parenthesis, the condition is true, and so the + yes-pattern is executed and a closing parenthesis is required. Other- + wise, since no-pattern is not present, the subpattern matches nothing. + In other words, this pattern matches a sequence of non-parentheses, optionally enclosed in parentheses. - If you were embedding this pattern in a larger one, you could use a + If you were embedding this pattern in a larger one, you could use a relative reference: ...other stuff... ( \( )? [^()]+ (?(-1) \) ) ... - This makes the fragment independent of the parentheses in the larger + This makes the fragment independent of the parentheses in the larger pattern. Checking for a used subpattern by name - Perl uses the syntax (?(<name>)...) or (?('name')...) to test for a - used subpattern by name. For compatibility with earlier versions of - PCRE, which had this facility before Perl, the syntax (?(name)...) is - also recognized. However, there is a possible ambiguity with this syn- - tax, because subpattern names may consist entirely of digits. PCRE - looks first for a named subpattern; if it cannot find one and the name - consists entirely of digits, PCRE looks for a subpattern of that num- - ber, which must be greater than zero. Using subpattern names that con- - sist entirely of digits is not recommended. + Perl uses the syntax (?(<name>)...) or (?('name')...) to test for a + used subpattern by name. For compatibility with earlier versions of + PCRE, which had this facility before Perl, the syntax (?(name)...) is + also recognized. Rewriting the above example to use a named subpattern gives this: @@ -7032,111 +7188,116 @@ CALLOUTS tion is called. It is provided with the number of the callout, the position in the pattern, and, optionally, one item of data originally supplied by the caller of the matching function. The callout function - may cause matching to proceed, to backtrack, or to fail altogether. A - complete description of the interface to the callout function is given - in the pcrecallout documentation. + may cause matching to proceed, to backtrack, or to fail altogether. + + By default, PCRE implements a number of optimizations at compile time + and 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, and a + complete description of the interface to the callout function, are + given in the pcrecallout documentation. 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 - problems during upgrades." The same remarks apply to the PCRE features + 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 PCRE 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 may take either form, possibly behaving - differently depending on whether or not a name is present. A name is + (*VERB) or (*VERB:NAME). Some may take either form, possibly behaving + differently depending on whether or not a name is present. A name is any sequence of characters that does not include a closing parenthesis. The maximum length of 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 + 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 pattern. - Since these verbs are specifically related to backtracking, most of - them can be used only when the pattern is to be matched using one of - the traditional matching functions, because these use a backtracking - algorithm. With the exception of (*FAIL), which behaves like a failing - negative assertion, the backtracking control verbs cause an error if + Since these verbs are specifically related to backtracking, most of + them can be used only when the pattern is to be matched using one of + the traditional matching functions, because these use a backtracking + algorithm. With the exception of (*FAIL), which behaves like a failing + negative assertion, the backtracking control verbs cause an error if encountered by a 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. Optimizations that affect backtracking verbs - PCRE contains some optimizations that are used to speed up matching by + PCRE 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 PCRE_NO_START_OPTIMIZE option when calling pcre_com- + by setting the PCRE_NO_START_OPTIMIZE option when calling pcre_com- pile() or pcre_exec(), or by starting the pattern with (*NO_START_OPT). There is more discussion of this option in the section entitled "Option bits for pcre_exec()" in the pcreapi 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 PCRE. 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 PCRE. 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 "Extra data for - pcre_exec()" in the pcreapi documentation. Here is an example of - pcretest output, where the /K modifier requests the retrieval and out- + 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 "Extra data for + pcre_exec()" in the pcreapi documentation. Here is an example of + pcretest output, where the /K modifier requests the retrieval and out- putting of (*MARK) data: re> /X(*MARK:A)Y|X(*MARK:B)Z/K @@ -7148,73 +7309,73 @@ BACKTRACKING CONTROL 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/K 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 PCRE_NO_START_OPTIMIZE option (see above) to + If you are interested in (*MARK) values after failed matches, you + should probably set the PCRE_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 or an assertion that is true, its effect - is confined to that group, because once the group has been matched, - there is never any backtracking into it. In this situation, backtrack- - ing can "jump back" to the left of the entire atomic group or asser- - tion. (Remember also, as stated above, that this localization also + is confined to that group, because once the group has been matched, + there is never any backtracking into it. In this situation, backtrack- + ing can "jump back" to the left of the entire atomic group or asser- + tion. (Remember also, as stated above, that this localization also applies in subroutine calls.) - 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 + (*COMMIT) is the only backtracking verb that is encountered, once it has been passed pcre_exec() is committed to finding a match at the cur- rent 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 PCRE'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 PCRE's start-of-match optimizations are turned off, as shown in this pcretest example: re> /(*COMMIT)abc/ @@ -7223,205 +7384,205 @@ BACKTRACKING CONTROL xyzabc\Y No match - PCRE knows that any match must start with "a", so the optimization - skips along the subject to "a" before running the first match attempt, - which succeeds. When the optimization is disabled by the \Y escape in + PCRE knows that any match must start with "a", so the optimization + skips along the subject to "a" before running the first match attempt, + which succeeds. When the optimization is disabled by the \Y escape in the second subject, the match starts at "x" and so the (*COMMIT) causes it 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) + (*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). (*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) 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) + 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). - 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) - cases it to be triggered, and its action is taken. There can never be a - backtrack onto (*COMMIT). + causes it to be triggered, and its action is taken. There can never be + a backtrack onto (*COMMIT). Backtracking verbs in repeated groups - PCRE differs from Perl in its handling of backtracking verbs in + PCRE 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 PCRE fails because the + If the subject is "abac", Perl matches, but PCRE 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 - pcreapi(3), pcrecallout(3), pcrematching(3), pcresyntax(3), pcre(3), + pcreapi(3), pcrecallout(3), pcrematching(3), pcresyntax(3), pcre(3), pcre16(3), pcre32(3). @@ -7434,11 +7595,11 @@ AUTHOR REVISION - Last updated: 26 April 2013 + Last updated: 12 November 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRESYNTAX(3) Library Functions Manual PCRESYNTAX(3) @@ -7468,10 +7629,15 @@ CHARACTERS \n newline (hex 0A) \r carriage return (hex 0D) \t tab (hex 09) + \0dd character with octal code 0dd \ddd character with octal code ddd, or backreference + \o{ddd..} character with octal code ddd.. \xhh character with hex code hh \x{hhh..} character with hex code hhh.. + Note that \0dd is always an octal code, and that \8 and \9 are the lit- + eral characters "8" and "9". + CHARACTER TYPES @@ -7494,9 +7660,12 @@ CHARACTER TYPES \W a "non-word" character \X a Unicode extended grapheme cluster - In PCRE, by default, \d, \D, \s, \S, \w, and \W recognize only ASCII - characters, even in a UTF mode. However, this can be changed by setting - the PCRE_UCP option. + By default, \d, \s, and \w match only ASCII characters, even in UTF-8 + mode or in the 16- bit and 32-bit libraries. However, if locale-spe- + cific matching is happening, \s and \w may also match characters with + code points in the range 128-255. If the PCRE_UCP option is set, the + behaviour of these escape sequences is changed to use Unicode proper- + ties and they match many more characters. GENERAL CATEGORY PROPERTIES FOR \p and \P @@ -7551,29 +7720,32 @@ PCRE SPECIAL CATEGORY PROPERTIES FOR \p and \P Xan Alphanumeric: union of properties L and N Xps POSIX space: property Z or tab, NL, VT, FF, CR - Xsp Perl space: property Z or tab, NL, FF, CR + Xsp Perl space: property Z or tab, NL, VT, FF, CR Xuc Univerally-named character: one that can be represented by a Universal Character Name Xwd Perl word: property Xan or underscore + Perl and POSIX space are now the same. Perl added VT to its space char- + acter set at release 5.18 and PCRE changed at release 8.34. + SCRIPT NAMES FOR \p AND \P - Arabic, Armenian, Avestan, Balinese, Bamum, Batak, Bengali, Bopomofo, - Brahmi, Braille, Buginese, Buhid, Canadian_Aboriginal, Carian, Chakma, - Cham, Cherokee, Common, Coptic, Cuneiform, Cypriot, Cyrillic, Deseret, - Devanagari, Egyptian_Hieroglyphs, Ethiopic, Georgian, Glagolitic, - Gothic, Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew, Hira- - gana, Imperial_Aramaic, Inherited, Inscriptional_Pahlavi, Inscrip- - tional_Parthian, Javanese, Kaithi, Kannada, Katakana, Kayah_Li, - Kharoshthi, Khmer, Lao, Latin, Lepcha, Limbu, Linear_B, Lisu, Lycian, + Arabic, Armenian, Avestan, Balinese, Bamum, Batak, Bengali, Bopomofo, + Brahmi, Braille, Buginese, Buhid, Canadian_Aboriginal, Carian, Chakma, + Cham, Cherokee, Common, Coptic, Cuneiform, Cypriot, Cyrillic, Deseret, + Devanagari, Egyptian_Hieroglyphs, Ethiopic, Georgian, Glagolitic, + Gothic, Greek, Gujarati, Gurmukhi, Han, Hangul, Hanunoo, Hebrew, Hira- + gana, Imperial_Aramaic, Inherited, Inscriptional_Pahlavi, Inscrip- + tional_Parthian, Javanese, Kaithi, Kannada, Katakana, Kayah_Li, + Kharoshthi, Khmer, Lao, Latin, Lepcha, Limbu, Linear_B, Lisu, Lycian, Lydian, Malayalam, Mandaic, Meetei_Mayek, Meroitic_Cursive, - Meroitic_Hieroglyphs, Miao, Mongolian, Myanmar, New_Tai_Lue, Nko, - Ogham, Old_Italic, Old_Persian, Old_South_Arabian, Old_Turkic, - Ol_Chiki, Oriya, Osmanya, Phags_Pa, Phoenician, Rejang, Runic, Samari- - tan, Saurashtra, Sharada, Shavian, Sinhala, Sora_Sompeng, Sundanese, - Syloti_Nagri, Syriac, Tagalog, Tagbanwa, Tai_Le, Tai_Tham, Tai_Viet, - Takri, Tamil, Telugu, Thaana, Thai, Tibetan, Tifinagh, Ugaritic, Vai, + Meroitic_Hieroglyphs, Miao, Mongolian, Myanmar, New_Tai_Lue, Nko, + Ogham, Old_Italic, Old_Persian, Old_South_Arabian, Old_Turkic, + Ol_Chiki, Oriya, Osmanya, Phags_Pa, Phoenician, Rejang, Runic, Samari- + tan, Saurashtra, Sharada, Shavian, Sinhala, Sora_Sompeng, Sundanese, + Syloti_Nagri, Syriac, Tagalog, Tagbanwa, Tai_Le, Tai_Tham, Tai_Viet, + Takri, Tamil, Telugu, Thaana, Thai, Tibetan, Tifinagh, Ugaritic, Vai, Yi. @@ -7600,8 +7772,8 @@ CHARACTER CLASSES word same as \w xdigit hexadecimal digit - In PCRE, POSIX character set names recognize only ASCII characters by - default, but some of them use Unicode properties if PCRE_UCP is set. + In PCRE, POSIX character set names recognize only ASCII characters by + default, but some of them use Unicode properties if PCRE_UCP is set. You can use \Q...\E inside a character class. @@ -7682,7 +7854,7 @@ OPTION SETTING (?x) extended (ignore white space) (?-...) unset option(s) - The following are recognized only at the start of a pattern or after + The following are recognized only at the start of a pattern or after one of the newline-setting options with similar syntax: (*LIMIT_MATCH=d) set the match limit to d (decimal number) @@ -7694,6 +7866,9 @@ OPTION SETTING (*UTF) set appropriate UTF mode for the library in use (*UCP) set PCRE_UCP (use Unicode properties for \d etc) + Note that LIMIT_MATCH and LIMIT_RECURSION can only reduce the value of + the limits set by the caller of pcre_exec(), not increase them. + LOOKAHEAD AND LOOKBEHIND ASSERTIONS @@ -7818,11 +7993,11 @@ AUTHOR REVISION - Last updated: 26 April 2013 + Last updated: 12 November 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREUNICODE(3) Library Functions Manual PCREUNICODE(3) @@ -8040,8 +8215,8 @@ REVISION Last updated: 27 February 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREJIT(3) Library Functions Manual PCREJIT(3) @@ -8453,8 +8628,8 @@ REVISION Last updated: 17 March 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREPARTIAL(3) Library Functions Manual PCREPARTIAL(3) @@ -8742,6 +8917,16 @@ MULTI-SEGMENT MATCHING WITH pcre_dfa_exec() OR pcre[16|32]_dfa_exec() matched string. It is up to the calling program to do that if it needs to. + That means that, for an unanchored pattern, if a continued match fails, + it is not possible to try again at a new starting point. All this + facility is capable of doing is continuing with the previous match + attempt. In the previous example, if the second set of data is "ug23" + the result is no match, even though there would be a match for "aug23" + if the entire string were given at once. Depending on the application, + this may or may not be what you want. The only way to allow for start- + ing again at the next character is to retain the matched part of the + subject and try a new complete match. + You can set the PCRE_PARTIAL_SOFT or PCRE_PARTIAL_HARD options with PCRE_DFA_RESTART to continue partial matching over multiple segments. This facility can be used to pass very long subject strings to the DFA @@ -8925,11 +9110,11 @@ AUTHOR REVISION - Last updated: 20 February 2013 + Last updated: 02 July 2013 Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREPRECOMPILE(3) Library Functions Manual PCREPRECOMPILE(3) @@ -9029,6 +9214,10 @@ RE-USING A PRECOMPILED PATTERN is used to pass this data, as described in the section on matching a pattern in the pcreapi documentation. + Warning: The tables that pcre_exec() and pcre_dfa_exec() use must be + the same as those that were used when the pattern was compiled. If this + is not the case, the behaviour is undefined. + If you did not provide custom character tables when the pattern was compiled, the pointer in the compiled pattern is NULL, which causes the matching functions to use PCRE's internal tables. Thus, you do not need @@ -9060,11 +9249,11 @@ AUTHOR REVISION - Last updated: 24 June 2012 - Copyright (c) 1997-2012 University of Cambridge. + Last updated: 12 November 2013 + Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREPERFORM(3) Library Functions Manual PCREPERFORM(3) @@ -9233,8 +9422,8 @@ REVISION Last updated: 25 August 2012 Copyright (c) 1997-2012 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCREPOSIX(3) Library Functions Manual PCREPOSIX(3) @@ -9497,8 +9686,8 @@ REVISION Last updated: 09 January 2012 Copyright (c) 1997-2012 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRECPP(3) Library Functions Manual PCRECPP(3) @@ -9840,8 +10029,8 @@ REVISION Last updated: 08 January 2012 ------------------------------------------------------------------------------ - - + + PCRESAMPLE(3) Library Functions Manual PCRESAMPLE(3) @@ -9941,38 +10130,43 @@ SIZE AND OTHER LIMITATIONS never in practice be relevant. The maximum length of a compiled pattern is approximately 64K data - units (bytes for the 8-bit library, 32-bit units for the 32-bit + units (bytes for the 8-bit library, 16-bit units for the 16-bit library, and 32-bit units for the 32-bit library) if PCRE is compiled - with the default internal linkage size of 2 bytes. If you want to - process regular expressions that are truly enormous, you can compile - PCRE with an internal linkage size of 3 or 4 (when building the 16-bit - or 32-bit library, 3 is rounded up to 4). See the README file in the - source distribution and the pcrebuild documentation for details. In - these cases the limit is substantially larger. However, the speed of + with the default internal linkage size, which is 2 bytes for the 8-bit + and 16-bit libraries, and 4 bytes for the 32-bit library. If you want + to process regular expressions that are truly enormous, you can compile + PCRE with an internal linkage size of 3 or 4 (when building the 16-bit + or 32-bit library, 3 is rounded up to 4). See the README file in the + source distribution and the pcrebuild documentation for details. In + these cases the limit is substantially larger. However, the speed of execution is slower. All values in repeating quantifiers must be less than 65536. There is no limit to the number of parenthesized subpatterns, but there - can be no more than 65535 capturing subpatterns. + 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 order to limit the amount of system stack + used at compile time. The limit can be specified when PCRE is built; + the default is 250. There is a limit to the number of forward references to subsequent sub- - patterns of around 200,000. Repeated forward references with fixed - upper limits, for example, (?2){0,100} when subpattern number 2 is to - the right, are included in the count. There is no limit to the number + patterns of around 200,000. Repeated forward references with fixed + upper limits, for example, (?2){0,100} when subpattern number 2 is to + the right, are included in the count. There is no limit to the number of backward references. The maximum length of name for a named subpattern is 32 characters, and the maximum number of named subpatterns is 10000. - The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or - (*THEN) verb is 255 for the 8-bit library and 65535 for the 16-bit and - 32-bit library. + The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or + (*THEN) verb is 255 for the 8-bit library and 65535 for the 16-bit and + 32-bit libraries. - The maximum length of a subject string is the largest positive number - that an integer variable can hold. However, when using the traditional + The maximum length of a subject string is the largest positive number + that an integer variable can hold. However, when using the traditional matching function, PCRE uses recursion to handle subpatterns and indef- - inite repetition. This means that the available stack space may limit + inite repetition. This means that the available stack space may limit the size of a subject string that can be processed by certain patterns. For a discussion of stack issues, see the pcrestack documentation. @@ -9986,11 +10180,11 @@ AUTHOR REVISION - Last updated: 04 May 2012 - Copyright (c) 1997-2012 University of Cambridge. + Last updated: 05 November 2013 + Copyright (c) 1997-2013 University of Cambridge. ------------------------------------------------------------------------------ - - + + PCRESTACK(3) Library Functions Manual PCRESTACK(3) @@ -10175,5 +10369,5 @@ REVISION Last updated: 24 June 2012 Copyright (c) 1997-2012 University of Cambridge. ------------------------------------------------------------------------------ - - + + diff --git a/doc/pcre_compile.3 b/doc/pcre_compile.3 index d4f1ba8..5c16ebe 100644 --- a/doc/pcre_compile.3 +++ b/doc/pcre_compile.3 @@ -61,7 +61,7 @@ The option bits are: PCRE_NO_AUTO_CAPTURE Disable numbered capturing paren- theses (named ones available) PCRE_NO_AUTO_POSSESS Disable auto-possessification - PCRE_NO_START_OPTIMIZE Disable match-time start optimizations + PCRE_NO_START_OPTIMIZE Disable match-time start optimizations PCRE_NO_UTF16_CHECK Do not check the pattern for UTF-16 validity (only relevant if PCRE_UTF16 is set) diff --git a/doc/pcre_compile2.3 b/doc/pcre_compile2.3 index 5e46a17..3774201 100644 --- a/doc/pcre_compile2.3 +++ b/doc/pcre_compile2.3 @@ -66,7 +66,7 @@ The option bits are: PCRE_NO_AUTO_CAPTURE Disable numbered capturing paren- theses (named ones available) PCRE_NO_AUTO_POSSESS Disable auto-possessification - PCRE_NO_START_OPTIMIZE Disable match-time start optimizations + PCRE_NO_START_OPTIMIZE Disable match-time start optimizations PCRE_NO_UTF16_CHECK Do not check the pattern for UTF-16 validity (only relevant if PCRE_UTF16 is set) diff --git a/doc/pcre_config.3 b/doc/pcre_config.3 index 8900416..d3de14b 100644 --- a/doc/pcre_config.3 +++ b/doc/pcre_config.3 @@ -33,7 +33,7 @@ point to an unsigned long integer. The available codes are: target architecture for the JIT compiler, or NULL if there is no JIT support PCRE_CONFIG_LINK_SIZE Internal link size: 2, 3, or 4 - PCRE_CONFIG_PARENS_LIMIT Parentheses nesting limit + PCRE_CONFIG_PARENS_LIMIT Parentheses nesting limit PCRE_CONFIG_MATCH_LIMIT Internal resource limit PCRE_CONFIG_MATCH_LIMIT_RECURSION Internal recursion depth limit diff --git a/doc/pcreapi.3 b/doc/pcreapi.3 index 374c701..ebbd20f 100644 --- a/doc/pcreapi.3 +++ b/doc/pcreapi.3 @@ -462,8 +462,8 @@ documentation. .sp PCRE_CONFIG_PARENS_LIMIT .sp -The output is a long integer that gives the maximum depth of nesting of -parentheses (of any kind) in a pattern. This limit is imposed to cap the amount +The output is a long integer that gives the maximum depth of nesting 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 PCRE is built; the default is 250. .sp @@ -657,7 +657,7 @@ ignored except when escaped or inside a character class. However, white space is not allowed within sequences such as (?> that introduce various parenthesized subpatterns, nor within a numerical quantifier such as {1,3}. However, ignorable white space is permitted between an item and a following -quantifier and between a quantifier and a following + that indicates +quantifier and between a quantifier and a following + that indicates possessiveness. .P White space did not used to include the VT character (code 11), because Perl @@ -815,11 +815,11 @@ in Perl. .sp PCRE_NO_AUTO_POSSESS .sp -If this option is set, it disables "auto-possessification". This is an +If this option is set, it disables "auto-possessification". This 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 of them are never taken. You can set -this option if you want the matching functions to do a full unoptimized search +this option if you want the matching functions to do a full unoptimized search and run all the callouts, but it is mainly provided for testing purposes. .sp PCRE_NO_START_OPTIMIZE @@ -988,7 +988,7 @@ have fallen out of use. To avoid confusion, they have not been re-used. 78 setting UTF is disabled by the application 79 non-hex character in \ex{} (closing brace missing?) 80 non-octal character in \eo{} (closing brace missing?) - 81 missing opening brace after \eo + 81 missing opening brace after \eo 82 parentheses are too deeply nested 83 invalid range in character class .sp @@ -1331,8 +1331,8 @@ be used. .sp PCRE_INFO_MATCH_EMPTY .sp -Return 1 if the pattern can match an empty string, otherwise 0. The fourth -argument should point to an \fBint\fP variable. +Return 1 if the pattern can match an empty string, otherwise 0. The fourth +argument should point to an \fBint\fP variable. .sp PCRE_INFO_MATCHLIMIT .sp @@ -2816,7 +2816,7 @@ matching string is given first. If there were too many matches to fit into \fIovector\fP, the yield of the function is zero, and the vector is filled with the longest matches. Unlike \fBpcre_exec()\fP, \fBpcre_dfa_exec()\fP can use the entire \fIovector\fP for returning matched strings. - +.P NOTE: PCRE's "auto-possessification" optimization usually applies to character repeats at the end of a pattern (as well as internally). For example, the pattern "a\ed+" is compiled as if it were "a\ed++" because there is no point diff --git a/doc/pcrecompat.3 b/doc/pcrecompat.3 index b931efe..0cc4019 100644 --- a/doc/pcrecompat.3 +++ b/doc/pcrecompat.3 @@ -122,12 +122,12 @@ an error is given at compile time. .P 15. Perl recognizes comments in some places that PCRE does not, for example, between the ( and ? at the start of a subpattern. If the /x modifier is set, -Perl allows white space between ( and ? (though current Perls warn that this is +Perl allows white space between ( and ? (though current Perls warn that this is deprecated) but PCRE never does, even if the PCRE_EXTENDED option is set. .P 16. Perl, when in warning mode, gives warnings for character classes such as -[A-\ed] or [a-[:digit:]]. It then treats the hyphens as literals. PCRE has no -warning features, so it gives an error in these cases because they are almost +[A-\ed] or [a-[:digit:]]. It then treats the hyphens as literals. PCRE has no +warning features, so it gives an error in these cases because they are almost certainly user mistakes. .P 17. In PCRE, the upper/lower case character properties Lu and Ll are not diff --git a/doc/pcrepartial.3 b/doc/pcrepartial.3 index 911e6d2..14d0124 100644 --- a/doc/pcrepartial.3 +++ b/doc/pcrepartial.3 @@ -282,9 +282,9 @@ program to do that if it needs to. .P That means that, for an unanchored pattern, if a continued match fails, it is not possible to try again at a new starting point. All this facility is capable -of doing is continuing with the previous match attempt. In the previous -example, if the second set of data is "ug23" the result is no match, even -though there would be a match for "aug23" if the entire string were given at +of doing is continuing with the previous match attempt. In the previous +example, if the second set of data is "ug23" the result is no match, even +though there would be a match for "aug23" if the entire string were given at once. Depending on the application, this may or may not be what you want. The only way to allow for starting again at the next character is to retain the matched part of the subject and try a new complete match. diff --git a/doc/pcrepattern.3 b/doc/pcrepattern.3 index cd2060b..7dd951f 100644 --- a/doc/pcrepattern.3 +++ b/doc/pcrepattern.3 @@ -90,7 +90,7 @@ table. .SS "Disabling auto-possessification" .rs .sp -If a pattern starts with (*NO_AUTO_POSSESS), it has the same effect as setting +If a pattern starts with (*NO_AUTO_POSSESS), it has the same effect as setting the PCRE_NO_AUTO_POSSESS option at compile time. This stops PCRE from making quantifiers possessive when what follows cannot match the repeated item. For example, by default a+b is treated as a++b. For more details, see the @@ -317,9 +317,9 @@ one of the following escape sequences than the binary character it represents: \en linefeed (hex 0A) \er carriage return (hex 0D) \et tab (hex 09) - \e0dd character with octal code 0dd + \e0dd character with octal code 0dd \eddd character with octal code ddd, or back reference - \eo{ddd..} character with octal code ddd.. + \eo{ddd..} character with octal code ddd.. \exhh character with hex code hh \ex{hhh..} character with hex code hhh.. (non-JavaScript mode) \euhhhh character with hex code hhhh (JavaScript mode only) @@ -346,7 +346,7 @@ specifies two binary zeros followed by a BEL character (code value 7). Make sure you supply two digits after the initial zero if the pattern character that follows is itself an octal digit. .P -The escape \eo must be followed by a sequence of octal digits, enclosed in +The escape \eo must be followed by a sequence of octal digits, enclosed in braces. An error occurs if this is not the case. This escape is a recent addition to Perl; it provides way of specifying character code points as octal numbers greater than 0777, and it also allows octal numbers and back references @@ -435,7 +435,7 @@ limited to certain values, as follows: 32-bit UTF-32 mode less than 0x10ffff and a valid codepoint .sp Invalid Unicode codepoints are the range 0xd800 to 0xdfff (the so-called -"surrogate" codepoints), and 0xffef. +"surrogate" codepoints), and 0xffef. . . .SS "Escape sequences in character classes" @@ -535,8 +535,8 @@ For compatibility with Perl, \es did not used to match the VT character (code 11), which made it different from the the POSIX "space" class. However, Perl added VT at release 5.18, and PCRE followed suit at release 8.34. The default \es characters are now HT (9), LF (10), VT (11), FF (12), CR (13), and space -(32), which are defined as white space in the "C" locale. This list may vary if -locale-specific matching is taking place; in particular, in some locales the +(32), which are defined as white space in the "C" locale. This list may vary if +locale-specific matching is taking place; in particular, in some locales the "non-breaking space" character (\exA0) is recognized as white space. .P A "word" character is an underscore or any character that is a letter or digit. @@ -1257,7 +1257,7 @@ The minus (hyphen) character can be used to specify a range of characters in a character class. For example, [d-m] matches any letter between d and m, inclusive. If a minus character is required in a class, it must be escaped with a backslash or appear in a position where it cannot be interpreted as -indicating a range, typically as the first or last character in the class, or +indicating a range, typically as the first or last character in the class, or immediately after a range. For example, [b-d-z] matches letters in the range b to d, a hyphen character, or z. .P @@ -1376,21 +1376,21 @@ other sequences, as follows: [:upper:] becomes \ep{Lu} [:word:] becomes \ep{Xwd} .sp -Negated versions, such as [:^alpha:] use \eP instead of \ep. Three other POSIX +Negated versions, such as [:^alpha:] use \eP instead of \ep. Three other POSIX classes are handled specially in UCP mode: .TP 10 [:graph:] -This matches characters that have glyphs that mark the page when printed. In -Unicode property terms, it matches all characters with the L, M, N, P, S, or Cf +This matches characters that have glyphs that mark the page when printed. In +Unicode property terms, it matches all characters with the L, M, N, P, S, or Cf properties, except for: .sp U+061C Arabic Letter Mark - U+180E Mongolian Vowel Separator + U+180E Mongolian Vowel Separator U+2066 - U+2069 Various "isolate"s .sp .TP 10 [:print:] -This matches the same characters as [:graph:] plus space characters that are +This matches the same characters as [:graph:] plus space characters that are not controls, that is, characters with the Zs property. .TP 10 [:punct:] @@ -1619,7 +1619,7 @@ conditions, .\" can be made by name as well as by number. .P -Names consist of up to 32 alphanumeric characters and underscores, but must +Names consist of up to 32 alphanumeric characters and underscores, but must start with a non-digit. Named capturing parentheses are still allocated numbers as well as names, exactly as if the names were not present. The PCRE API provides function calls for extracting the name-to-number translation table @@ -1650,12 +1650,12 @@ for the first (and in this example, the only) subpattern of that name that matched. This saves searching to find which numbered subpattern it was. .P If you make a back reference to a non-unique named subpattern from elsewhere in -the pattern, the subpatterns to which the name refers are checked in the order -in which they appear in the overall pattern. The first one that is set is used -for the reference. For example, this pattern matches both "foofoo" and +the pattern, the subpatterns to which the name refers are checked in the order +in which they appear in the overall pattern. The first one that is set is used +for the reference. For example, this pattern matches both "foofoo" and "barbar" but not "foobar" or "barfoo": .sp - (?:(?<n>foo)|(?<n>bar))\k<n> + (?:(?<n>foo)|(?<n>bar))\ek<n> .sp .P If you make a subroutine call to a non-unique named subpattern, the one that @@ -2356,7 +2356,7 @@ This makes the fragment independent of the parentheses in the larger pattern. .sp Perl uses the syntax (?(<name>)...) or (?('name')...) to test for a used subpattern by name. For compatibility with earlier versions of PCRE, which had -this facility before Perl, the syntax (?(name)...) is also recognized. +this facility before Perl, the syntax (?(name)...) is also recognized. .P Rewriting the above example to use a named subpattern gives this: .sp diff --git a/doc/pcresyntax.3 b/doc/pcresyntax.3 index a9aa1d2..87f0cea 100644 --- a/doc/pcresyntax.3 +++ b/doc/pcresyntax.3 @@ -29,14 +29,14 @@ documentation. This document contains a quick-reference summary of the syntax. \en newline (hex 0A) \er carriage return (hex 0D) \et tab (hex 09) - \e0dd character with octal code 0dd + \e0dd character with octal code 0dd \eddd character with octal code ddd, or backreference - \eo{ddd..} character with octal code ddd.. + \eo{ddd..} character with octal code ddd.. \exhh character with hex code hh \ex{hhh..} character with hex code hhh.. .sp -Note that \e0dd is always an octal code, and that \e8 and \e9 are the literal -characters "8" and "9". +Note that \e0dd is always an octal code, and that \e8 and \e9 are the literal +characters "8" and "9". . . .SH "CHARACTER TYPES" @@ -126,7 +126,7 @@ is changed to use Unicode properties and they match many more characters. Xuc Univerally-named character: one that can be represented by a Universal Character Name Xwd Perl word: property Xan or underscore -.sp +.sp Perl and POSIX space are now the same. Perl added VT to its space character set at release 5.18 and PCRE changed at release 8.34. . diff --git a/doc/pcretest.1 b/doc/pcretest.1 index 6718349..f17c6f2 100644 --- a/doc/pcretest.1 +++ b/doc/pcretest.1 @@ -156,8 +156,8 @@ equivalent to adding \fB/M\fP to each regular expression. The size is given in bytes for both libraries. .TP 10 \fB-O\fP -Behave as if each pattern has the \fB/O\fP modifier, that is disable -auto-possessification for all patterns. +Behave as if each pattern has the \fB/O\fP modifier, that is disable +auto-possessification for all patterns. .TP 10 \fB-o\fP \fIosize\fP Set the number of elements in the output vector that is used when calling @@ -232,8 +232,8 @@ The default is to iterate 500000 times. This is like \fB-t\fP except that it times only the matching phase, not the compile or study phases. .TP 10 -\fB-T\fp \fB-TM\fP -These behave like \fB-t\fP and \fB-tm\fP, but in addition, at the end of a run, +\fB-T\fP \fB-TM\fP +These behave like \fB-t\fP and \fB-tm\fP, but in addition, at the end of a run, the total times for all compiles, studies, and matches are output. . . @@ -612,17 +612,17 @@ Unicode property support, this line appears: .sp < forbid 8W .sp -This locks out the /8 and /W modifiers. An immediate error is given if they are -subsequently encountered. If the character string contains < but not >, all the -multi-character modifiers that begin with < are locked out. Otherwise, such +This locks out the /8 and /W modifiers. An immediate error is given if they are +subsequently encountered. If the character string contains < but not >, all the +multi-character modifiers that begin with < are locked out. Otherwise, such modifiers must be explicitly listed, for example: .sp < forbid <JS><cr> .sp -There must be a single space between < and "forbid" for this feature to be +There must be a single space between < and "forbid" for this feature to be recognised. If there is not, the line is interpreted either as a request to re-load a pre-compiled pattern (see "SAVING AND RELOADING COMPILED PATTERNS" -below) or, if there is a another < character, as a pattern that uses < as its +below) or, if there is a another < character, as a pattern that uses < as its delimiter. . . @@ -649,7 +649,7 @@ recognized: \ev vertical tab (\ex0b) \ennn octal character (up to 3 octal digits); always a byte unless > 255 in UTF-8 or 16-bit or 32-bit mode - \eo{dd...} octal character (any number of octal digits} + \eo{dd...} octal character (any number of octal digits} \exhh hexadecimal byte (up to 2 hex digits) \ex{hh...} hexadecimal character (any number of hex digits) .\" JOIN diff --git a/doc/pcretest.txt b/doc/pcretest.txt index 2644e27..f060993 100644 --- a/doc/pcretest.txt +++ b/doc/pcretest.txt @@ -138,32 +138,35 @@ COMMAND LINE OPTIONS compiled. This is equivalent to adding /M to each regular expression. The size is given in bytes for both libraries. - -o osize Set the number of elements in the output vector that is used - when calling pcre[16|32]_exec() or pcre[16|32]_dfa_exec() to - be osize. The default value is 45, which is enough for 14 + -O Behave as if each pattern has the /O modifier, that is dis- + able auto-possessification for all patterns. + + -o osize Set the number of elements in the output vector that is used + when calling pcre[16|32]_exec() or pcre[16|32]_dfa_exec() to + be osize. The default value is 45, which is enough for 14 capturing subexpressions for pcre[16|32]_exec() or 22 differ- - ent matches for pcre[16|32]_dfa_exec(). The vector size can - be changed for individual matching calls by including \O in + ent matches for pcre[16|32]_dfa_exec(). The vector size can + be changed for individual matching calls by including \O in the data line (see below). - -p Behave as if each pattern has the /P modifier; the POSIX - wrapper API is used to call PCRE. None of the other options - has any effect when -p is set. This option can be used only + -p Behave as if each pattern has the /P modifier; the POSIX + wrapper API is used to call PCRE. None of the other options + has any effect when -p is set. This option can be used only with the 8-bit library. - -q Do not output the version number of pcretest at the start of + -q Do not output the version number of pcretest at the start of execution. - -S size On Unix-like systems, set the size of the run-time stack to + -S size On Unix-like systems, set the size of the run-time stack to size megabytes. - -s or -s+ Behave as if each pattern has the /S modifier; in other - words, force each pattern to be studied. If -s+ is used, all - the JIT compile options are passed to pcre[16|32]_study(), - causing just-in-time optimization to be set up if it is - available, for both full and partial matching. Specific JIT + -s or -s+ Behave as if each pattern has the /S modifier; in other + words, force each pattern to be studied. If -s+ is used, all + the JIT compile options are passed to pcre[16|32]_study(), + causing just-in-time optimization to be set up if it is + available, for both full and partial matching. Specific JIT compile options can be selected by following -s+ with a digit - in the range 1 to 7, which selects the JIT compile modes as + in the range 1 to 7, which selects the JIT compile modes as follows: 1 normal match only @@ -173,115 +176,119 @@ COMMAND LINE OPTIONS 6 soft and hard partial match 7 all three modes (default) - If -s++ is used instead of -s+ (with or without a following - digit), the text "(JIT)" is added to the first output line + If -s++ is used instead of -s+ (with or without a following + digit), the text "(JIT)" is added to the first output line after a match or no match when JIT-compiled code was actually used. - Note that there are pattern options that can override -s, + Note that there are pattern options that can override -s, either specifying no studying at all, or suppressing JIT com- pilation. - If the /I or /D option is present on a pattern (requesting - output about the compiled pattern), information about the - result of studying is not included when studying is caused - only by -s and neither -i nor -d is present on the command - line. This behaviour means that the output from tests that - are run with and without -s should be identical, except when + If the /I or /D option is present on a pattern (requesting + output about the compiled pattern), information about the + result of studying is not included when studying is caused + only by -s and neither -i nor -d is present on the command + line. This behaviour means that the output from tests that + are run with and without -s should be identical, except when options that output information about the actual running of a match are set. - The -M, -t, and -tm options, which give information about - resources used, are likely to produce different output with - and without -s. Output may also differ if the /C option is + The -M, -t, and -tm options, which give information about + resources used, are likely to produce different output with + and without -s. Output may also differ if the /C option is present on an individual pattern. This uses callouts to trace - the the matching process, and this may be different between - studied and non-studied patterns. If the pattern contains - (*MARK) items there may also be differences, for the same + the the matching process, and this may be different between + studied and non-studied patterns. If the pattern contains + (*MARK) items there may also be differences, for the same reason. The -s command line option can be overridden for spe- - cific patterns that should never be studied (see the /S pat- + cific patterns that should never be studied (see the /S pat- tern modifier below). - -t Run each compile, study, and match many times with a timer, - and output resulting time per compile or match (in millisec- - onds). Do not set -m with -t, because you will then get the - size output a zillion times, and the timing will be dis- - torted. You can control the number of iterations that are - used for timing by following -t with a number (as a separate - item on the command line). For example, "-t 1000" would iter- - ate 1000 times. The default is to iterate 500000 times. + -t Run each compile, study, and match many times with a timer, + and output the resulting times per compile, study, or match + (in milliseconds). Do not set -m with -t, because you will + then get the size output a zillion times, and the timing will + be distorted. You can control the number of iterations that + are used for timing by following -t with a number (as a sepa- + rate item on the command line). For example, "-t 1000" iter- + ates 1000 times. The default is to iterate 500000 times. -tm This is like -t except that it times only the matching phase, not the compile or study phases. + -T -TM These behave like -t and -tm, but in addition, at the end of + a run, the total times for all compiles, studies, and matches + are output. + DESCRIPTION - If pcretest is given two filename arguments, it reads from the first + If pcretest is given two filename arguments, it reads from the first and writes to the second. If it is given only one filename argument, it - reads from that file and writes to stdout. Otherwise, it reads from - stdin and writes to stdout, and prompts for each line of input, using + reads from that file and writes to stdout. Otherwise, it reads from + stdin and writes to stdout, and prompts for each line of input, using "re>" to prompt for regular expressions, and "data>" to prompt for data lines. - When pcretest is built, a configuration option can specify that it - should be linked with the libreadline library. When this is done, if + When pcretest is built, a configuration option can specify that it + should be linked with the libreadline library. When this is done, if the input is from a terminal, it is read using the readline() function. - This provides line-editing and history facilities. The output from the + This provides line-editing and history facilities. The output from the -help option states whether or not readline() will be used. The program handles any number of sets of input on a single input file. - Each set starts with a regular expression, and continues with any num- - ber of data lines to be matched against the pattern. + Each set starts with a regular expression, and continues with any num- + ber of data lines to be matched against that pattern. - Each data line is matched separately and independently. If you want to + Each data line is matched separately and independently. If you want to do 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 - data lines; the input buffer is automatically extended if it is too + to encode the newline sequences. There is no limit on the length of + data lines; the input buffer is automatically extended if it is too small. - An empty line signals the end of the data lines, at which point a new - regular expression is read. The regular expressions are given enclosed + An empty line signals the end of the data lines, at which point a new + regular expression is read. The regular expressions are given enclosed in any non-alphanumeric delimiters other than backslash, for example: /(a|bc)x+yz/ - White space before the initial delimiter is ignored. A regular expres- - sion may be continued over several input lines, in which case the new- - line characters are included within it. It is possible to include the + White space before the initial delimiter is ignored. A regular expres- + sion may be continued over several input lines, in which case the new- + line characters are included within it. It is possible to include the delimiter within the pattern by escaping it, for example /abc\/def/ - If you do so, the escape and the delimiter form part of the pattern, - but since delimiters are always non-alphanumeric, this does not affect - its interpretation. If the terminating delimiter is immediately fol- + If you do so, the escape and the delimiter form part of the pattern, + but since delimiters are always non-alphanumeric, this does not affect + 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/", + is interpreted as the first line of a pattern that starts with "abc/", causing pcretest to read the next line as a continuation of the regular expression. PATTERN MODIFIERS - A pattern may be followed by any number of modifiers, which are mostly - single characters, though some of these can be qualified by further - characters. Following Perl usage, these are referred to below as, for - example, "the /i modifier", even though the delimiter of the pattern - need not always be a slash, and no slash is used when writing modi- - fiers. White space may appear between the final pattern delimiter and - the first modifier, and between the modifiers themselves. For refer- - ence, here is a complete list of modifiers. They fall into several + A pattern may be followed by any number of modifiers, which are mostly + single characters, though some of these can be qualified by further + characters. Following Perl usage, these are referred to below as, for + example, "the /i modifier", even though the delimiter of the pattern + need not always be a slash, and no slash is used when writing modi- + fiers. White space may appear between the final pattern delimiter and + the first modifier, and between the modifiers themselves. For refer- + ence, here is a complete list of modifiers. They fall into several groups that are described in detail in the following sections. /8 set UTF mode @@ -307,6 +314,7 @@ PATTERN MODIFIERS /M show compiled memory size /m set PCRE_MULTILINE /N set PCRE_NO_AUTO_CAPTURE + /O set PCRE_NO_AUTO_POSSESS /P use the POSIX wrapper /S study the pattern after compilation /s set PCRE_DOTALL @@ -331,8 +339,8 @@ PATTERN MODIFIERS Perl-compatible modifiers The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE, - PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when - pcre[16|32]_compile() is called. These four modifier letters have the + PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when + pcre[16|32]_compile() is called. These four modifier letters have the same effect as they do in Perl. For example: /caseless/i @@ -340,7 +348,7 @@ PATTERN MODIFIERS Modifiers for other PCRE options - The following table shows additional modifiers for setting PCRE com- + The following table shows additional modifiers for setting PCRE com- pile-time options that do not correspond to anything in Perl: /8 PCRE_UTF8 ) when using the 8-bit @@ -359,6 +367,7 @@ PATTERN MODIFIERS /f PCRE_FIRSTLINE /J PCRE_DUPNAMES /N PCRE_NO_AUTO_CAPTURE + /O PCRE_NO_AUTO_POSSESS /U PCRE_UNGREEDY /W PCRE_UCP /X PCRE_EXTRA @@ -372,138 +381,138 @@ PATTERN MODIFIERS /<bsr_unicode> PCRE_BSR_UNICODE /<JS> PCRE_JAVASCRIPT_COMPAT - The modifiers that are enclosed in angle brackets are literal strings - as shown, including the angle brackets, but the letters within can be - in either case. This example sets multiline matching with CRLF as the + The modifiers that are enclosed in angle brackets are literal strings + as shown, including the angle brackets, but the letters within can be + in either case. This example sets multiline matching with CRLF as the line ending sequence: /^abc/m<CRLF> - As well as turning on the PCRE_UTF8/16/32 option, the /8 modifier - causes all non-printing characters in output strings to be printed + As well as turning on the PCRE_UTF8/16/32 option, the /8 modifier + causes all non-printing characters in output strings to be printed using the \x{hh...} notation. Otherwise, those less than 0x100 are out- put in hex without the curly brackets. - Full details of the PCRE options are given in the pcreapi documenta- + Full details of the PCRE options are given in the pcreapi documenta- tion. Finding all matches in a string - Searching for all possible matches within each subject string can be - requested by the /g or /G modifier. After finding a match, PCRE is + Searching for all possible matches within each subject string can be + requested by the /g or /G modifier. After finding a match, PCRE is called again to search the remainder of the subject string. The differ- ence between /g and /G is that the former uses the startoffset argument - to pcre[16|32]_exec() to start searching at a new point within the - entire string (which is in effect what Perl does), whereas the latter - passes over a shortened substring. This makes a difference to the - matching process if the pattern begins with a lookbehind assertion + to pcre[16|32]_exec() to start searching at a new point within the + entire string (which is in effect what Perl does), whereas the latter + passes over a shortened substring. This makes a difference to the + matching process if the pattern begins with a lookbehind assertion (including \b or \B). - If any call to pcre[16|32]_exec() in a /g or /G sequence matches an - empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and - PCRE_ANCHORED flags set in order to search for another, non-empty, - match at the same point. If this second match fails, the start offset - is advanced, and the normal match is retried. This imitates the way + If any call to pcre[16|32]_exec() in a /g or /G sequence matches an + empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and + PCRE_ANCHORED flags set in order to search for another, non-empty, + match at the same point. If this second 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() func- - tion. Normally, the start offset is advanced by one character, but if - the newline convention recognizes CRLF as a newline, and the current + tion. 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 is used. Other modifiers There are yet more modifiers for controlling the way pcretest operates. - The /+ modifier requests that as well as outputting the substring that - matched the entire pattern, pcretest 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. If the + modi- - fier appears twice, the same action is taken for captured substrings. - In each case the remainder is output on the following line with a plus - character following the capture number. Note that this modifier must - not immediately follow the /S modifier because /S+ and /S++ have other + The /+ modifier requests that as well as outputting the substring that + matched the entire pattern, pcretest 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. If the + modi- + fier appears twice, the same action is taken for captured substrings. + In each case the remainder is output on the following line with a plus + character following the capture number. Note that this modifier must + not immediately follow the /S modifier because /S+ and /S++ have other meanings. - The /= modifier requests that the values of all potential captured - parentheses be output after a match. By default, only those up to the + The /= modifier requests that the values of all potential captured + 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 pcre[16|32]_exec()). Values in the offsets vector cor- - responding to higher numbers should be set to -1, and these are output - as "<unset>". This modifier gives a way of checking that this is hap- + responding to higher numbers should be set to -1, and these are output + as "<unset>". This modifier gives a way of checking that this is hap- pening. - The /B modifier is a debugging feature. It requests that pcretest out- - put a representation of the compiled code after compilation. Normally - this information contains length and offset values; however, if /Z is - also present, this data is replaced by spaces. This is a special fea- - ture for use in the automatic test scripts; it ensures that the same + The /B modifier is a debugging feature. It requests that pcretest out- + put a representation of the compiled code after compilation. Normally + this information contains length and offset values; however, if /Z is + also present, this data is replaced by spaces. This is a special fea- + ture for use in the automatic test scripts; it ensures that the same output is generated for different internal link sizes. - The /D modifier is a PCRE debugging feature, and is equivalent to /BI, + The /D modifier is a PCRE debugging feature, and is equivalent to /BI, that is, both the /B and the /I modifiers. - The /F modifier causes pcretest to flip the byte order of the 2-byte + The /F modifier causes pcretest to flip the byte order of the 2-byte and 4-byte fields in the compiled pattern. This facility is for testing - the feature in PCRE that allows it to execute patterns that were com- + the feature in PCRE that allows it to execute patterns that were com- piled on a host with a different endianness. This feature is not avail- - able when the POSIX interface to PCRE is being used, that is, when the + able when the POSIX interface to PCRE is being used, that is, when the /P pattern modifier is specified. See also the section about saving and reloading compiled patterns below. - The /I modifier requests that pcretest output information about the - compiled pattern (whether it is anchored, has a fixed first character, - and so on). It does this by calling pcre[16|32]_fullinfo() after com- - piling a pattern. If the pattern is studied, the results of that are + The /I modifier requests that pcretest output information about the + compiled pattern (whether it is anchored, has a fixed first character, + and so on). It does this by calling pcre[16|32]_fullinfo() after com- + piling a pattern. If the pattern is studied, the results of that are also output. - The /K modifier requests pcretest to show names from backtracking con- - trol verbs that are returned from calls to pcre[16|32]_exec(). It - causes pcretest to create a pcre[16|32]_extra block if one has not - already been created by a call to pcre[16|32]_study(), and to set the - PCRE_EXTRA_MARK flag and the mark field within it, every time that - pcre[16|32]_exec() is called. If the variable that the mark field - points to is non-NULL for a match, non-match, or partial match, - pcretest prints the string to which it points. For a match, this is - shown on a line by itself, tagged with "MK:". For a non-match it is + The /K modifier requests pcretest to show names from backtracking con- + trol verbs that are returned from calls to pcre[16|32]_exec(). It + causes pcretest to create a pcre[16|32]_extra block if one has not + already been created by a call to pcre[16|32]_study(), and to set the + PCRE_EXTRA_MARK flag and the mark field within it, every time that + pcre[16|32]_exec() is called. If the variable that the mark field + points to is non-NULL for a match, non-match, or partial match, + pcretest prints the string to which it points. For a match, this is + shown on a line by itself, tagged with "MK:". For a non-match it is added to the message. - The /L modifier must be followed directly by the name of a locale, for + The /L modifier must be followed directly by the name of a locale, for example, /pattern/Lfr_FR For this reason, it must be the last modifier. The given locale is set, - pcre[16|32]_maketables() is called to build a set of character tables - for the locale, and this is then passed to pcre[16|32]_compile() when - compiling the regular expression. Without an /L (or /T) modifier, NULL - is passed as the tables pointer; that is, /L applies only to the + pcre[16|32]_maketables() is called to build a set of character tables + for the locale, and this is then passed to pcre[16|32]_compile() when + compiling the regular expression. Without an /L (or /T) modifier, NULL + is passed as the tables pointer; that is, /L applies only to the expression on which it appears. - The /M modifier causes the size in bytes of the memory block used to - hold the compiled pattern to be output. This does not include the size - of the pcre[16|32] block; it is just the actual compiled data. If the + The /M modifier causes the size in bytes of the memory block used to + hold the compiled pattern to be output. This does not include the size + of the pcre[16|32] block; it is just the actual compiled data. If the pattern is successfully studied with the PCRE_STUDY_JIT_COMPILE option, the size of the JIT compiled code is also output. - The /S modifier causes pcre[16|32]_study() to be called after the - expression has been compiled, and the results used when the expression + The /S modifier causes pcre[16|32]_study() to be called after the + expression has been compiled, and the results used when the expression is matched. There are a number of qualifying characters that may follow /S. They may appear in any order. - If S is followed by an exclamation mark, pcre[16|32]_study() is called - with the PCRE_STUDY_EXTRA_NEEDED option, causing it always to return a + If /S is followed by an exclamation mark, pcre[16|32]_study() is called + with the PCRE_STUDY_EXTRA_NEEDED option, causing it always to return a pcre_extra block, even when studying discovers no useful information. If /S is followed by a second S character, it suppresses studying, even - if it was requested externally by the -s command line option. This - makes it possible to specify that certain patterns are always studied, + if it was requested externally by the -s command line option. This + makes it possible to specify that certain patterns are always studied, and others are never studied, independently of -s. This feature is used in the test files in a few cases where the output is different when the pattern is studied. - If the /S modifier is followed by a + character, the call to - pcre[16|32]_study() is made with all the JIT study options, requesting - just-in-time optimization support if it is available, for both normal - and partial matching. If you want to restrict the JIT compiling modes, + If the /S modifier is followed by a + character, the call to + pcre[16|32]_study() is made with all the JIT study options, requesting + just-in-time optimization support if it is available, for both normal + and partial matching. If you want to restrict the JIT compiling modes, you can follow /S+ with a digit in the range 1 to 7: 1 normal match only @@ -514,40 +523,40 @@ PATTERN MODIFIERS 7 all three modes (default) If /S++ is used instead of /S+ (with or without a following digit), the - text "(JIT)" is added to the first output line after a match or no + text "(JIT)" is added to the first output line after a match or no match when JIT-compiled code was actually used. - Note that there is also an independent /+ modifier; it must not be + Note that there is also an independent /+ modifier; it must not be given immediately after /S or /S+ because this will be misinterpreted. If JIT studying is successful, the compiled JIT code will automatically - be used when pcre[16|32]_exec() is run, except when incompatible run- - time options are specified. For more details, see the pcrejit documen- - tation. See also the \J escape sequence below for a way of setting the + be used when pcre[16|32]_exec() is run, except when incompatible run- + time options are specified. For more details, see the pcrejit documen- + tation. See also the \J escape sequence below for a way of setting the size of the JIT stack. - Finally, if /S is followed by a minus character, JIT compilation is - suppressed, even if it was requested externally by the -s command line - option. This makes it possible to specify that JIT is never to be used + Finally, if /S is followed by a minus character, JIT compilation is + suppressed, even if it was requested externally by the -s command line + option. This makes it possible to specify that JIT is never to be used for certain patterns. - The /T modifier must be followed by a single digit. It causes a spe- + The /T modifier must be followed by a single digit. It causes a spe- cific set of built-in character tables to be passed to pcre[16|32]_com- - pile(). It is used in the standard PCRE tests to check behaviour with + pile(). It is used in the standard PCRE tests to check behaviour with different character tables. The digit specifies the tables as follows: 0 the default ASCII tables, as distributed in pcre_chartables.c.dist 1 a set of tables defining ISO 8859 characters - In table 1, some characters whose codes are greater than 128 are iden- + In table 1, some characters whose codes are greater than 128 are iden- tified as letters, digits, spaces, etc. Using the POSIX wrapper API - The /P modifier causes pcretest to call PCRE via the POSIX wrapper API - rather than its native API. This supports only the 8-bit library. When - /P is set, the following modifiers set options for the regcomp() func- + The /P modifier causes pcretest to call PCRE via the POSIX wrapper API + rather than its native API. This supports only the 8-bit library. When + /P is set, the following modifiers set options for the regcomp() func- tion: /i REG_ICASE @@ -558,9 +567,40 @@ PATTERN MODIFIERS /W REG_UCP ) the POSIX standard /8 REG_UTF8 ) - The /+ modifier works as described above. All other modifiers are + The /+ modifier works as described above. All other modifiers are ignored. + Locking out certain modifiers + + PCRE can be compiled with or without support for certain features such + as UTF-8/16/32 or Unicode properties. Accordingly, the standard tests + are split up into a number of different files that are selected for + running depending on which features are available. When updating the + tests, it is all too easy to put a new test into the wrong file by mis- + take; for example, to put a test that requires UTF support into a file + that is used when it is not available. To help detect such mistakes as + early as possible, there is a facility for locking out specific modi- + fiers. If an input line for pcretest starts with the string "< forbid " + the following sequence of characters is taken as a list of forbidden + modifiers. For example, in the test files that must not use UTF or Uni- + code property support, this line appears: + + < forbid 8W + + This locks out the /8 and /W modifiers. An immediate error is given if + they are subsequently encountered. If the character string contains < + but not >, all the multi-character modifiers that begin with < are + locked out. Otherwise, such modifiers must be explicitly listed, for + example: + + < forbid <JS><cr> + + There must be a single space between < and "forbid" for this feature to + be recognised. If there is not, the line is interpreted either as a + request to re-load a pre-compiled pattern (see "SAVING AND RELOADING + COMPILED PATTERNS" below) or, if there is a another < character, as a + pattern that uses < as its delimiter. + DATA LINES @@ -583,6 +623,7 @@ DATA LINES \v vertical tab (\x0b) \nnn octal character (up to 3 octal digits); always a byte unless > 255 in UTF-8 or 16-bit or 32-bit mode + \o{dd...} octal character (any number of octal digits} \xhh hexadecimal byte (up to 2 hex digits) \x{hh...} hexadecimal character (any number of hex digits) \A pass the PCRE_ANCHORED option to pcre[16|32]_exec() @@ -974,50 +1015,51 @@ SAVING AND RELOADING COMPILED PATTERNS writing the file, pcretest expects to read a new pattern. A saved pattern can be reloaded into pcretest by specifying < and a - file name instead of a pattern. The name of the file must not contain a - < character, as otherwise pcretest will interpret the line as a pattern - delimited by < characters. For example: + file name instead of a pattern. There must be no space between < and + the file name, which must not contain a < character, as otherwise + pcretest will interpret the line as a pattern delimited by < charac- + ters. For example: re> </some/file Compiled pattern loaded from /some/file No study data - If the pattern was previously studied with the JIT optimization, the - JIT information cannot be saved and restored, and so is lost. When the - pattern has been loaded, pcretest proceeds to read data lines in the + If the pattern was previously studied with the JIT optimization, the + JIT information cannot be saved and restored, and so is lost. When the + pattern has been loaded, pcretest proceeds to read data lines in the usual way. - You can copy a file written by pcretest to a different host and reload - it there, even if the new host has opposite endianness to the one on - which the pattern was compiled. For example, you can compile on an i86 - machine and run on a SPARC machine. When a pattern is reloaded on a + You can copy a file written by pcretest to a different host and reload + it there, even if the new host has opposite endianness to the one on + which the pattern was compiled. For example, you can compile on an i86 + machine and run on a SPARC machine. When a pattern is reloaded on a host with different endianness, the confirmation message is changed to: Compiled pattern (byte-inverted) loaded from /some/file The test suite contains some saved pre-compiled patterns with different - endianness. These are reloaded using "<!" instead of just "<". This + endianness. These are reloaded using "<!" instead of just "<". This suppresses the "(byte-inverted)" text so that the output is the same on - all hosts. It also forces debugging output once the pattern has been + all hosts. It also forces debugging output once the pattern has been reloaded. - File names for saving and reloading can be absolute or relative, but - note that the shell facility of expanding a file name that starts with + File names for saving and reloading can be absolute or relative, but + note that the shell facility of expanding a file name that starts with a tilde (~) is not available. - The ability to save and reload files in pcretest is intended for test- - ing and experimentation. It is not intended for production use because - only a single pattern can be written to a file. Furthermore, there is - no facility for supplying custom character tables for use with a - reloaded pattern. If the original pattern was compiled with custom - tables, an attempt to match a subject string using a reloaded pattern - is likely to cause pcretest to crash. Finally, if you attempt to load + The ability to save and reload files in pcretest is intended for test- + ing and experimentation. It is not intended for production use because + only a single pattern can be written to a file. Furthermore, there is + no facility for supplying custom character tables for use with a + reloaded pattern. If the original pattern was compiled with custom + tables, an attempt to match a subject string using a reloaded pattern + is likely to cause pcretest to crash. Finally, if you attempt to load a file that is not in the correct format, the result is undefined. SEE ALSO - pcre(3), pcre16(3), pcre32(3), pcreapi(3), pcrecallout(3), pcrejit, + pcre(3), pcre16(3), pcre32(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematching(3), pcrepartial(d), pcrepattern(3), pcreprecompile(3). @@ -1030,5 +1072,5 @@ AUTHOR REVISION - Last updated: 26 April 2013 + Last updated: 12 November 2013 Copyright (c) 1997-2013 University of Cambridge. |