2014-10-20 18:48:14 +02:00
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<html>
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<head>
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<title>pcre2syntax specification</title>
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</head>
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<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
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<h1>pcre2syntax man page</h1>
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<p>
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Return to the <a href="index.html">PCRE2 index page</a>.
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</p>
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<p>
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This page is part of the PCRE2 HTML documentation. It was generated
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automatically from the original man page. If there is any nonsense in it,
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please consult the man page, in case the conversion went wrong.
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<br>
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<ul>
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<li><a name="TOC1" href="#SEC1">PCRE2 REGULAR EXPRESSION SYNTAX SUMMARY</a>
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<li><a name="TOC2" href="#SEC2">QUOTING</a>
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<li><a name="TOC3" href="#SEC3">CHARACTERS</a>
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<li><a name="TOC4" href="#SEC4">CHARACTER TYPES</a>
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<li><a name="TOC5" href="#SEC5">GENERAL CATEGORY PROPERTIES FOR \p and \P</a>
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<li><a name="TOC6" href="#SEC6">PCRE2 SPECIAL CATEGORY PROPERTIES FOR \p and \P</a>
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<li><a name="TOC7" href="#SEC7">SCRIPT NAMES FOR \p AND \P</a>
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<li><a name="TOC8" href="#SEC8">CHARACTER CLASSES</a>
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<li><a name="TOC9" href="#SEC9">QUANTIFIERS</a>
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<li><a name="TOC10" href="#SEC10">ANCHORS AND SIMPLE ASSERTIONS</a>
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<li><a name="TOC11" href="#SEC11">MATCH POINT RESET</a>
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<li><a name="TOC12" href="#SEC12">ALTERNATION</a>
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<li><a name="TOC13" href="#SEC13">CAPTURING</a>
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<li><a name="TOC14" href="#SEC14">ATOMIC GROUPS</a>
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<li><a name="TOC15" href="#SEC15">COMMENT</a>
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<li><a name="TOC16" href="#SEC16">OPTION SETTING</a>
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<li><a name="TOC17" href="#SEC17">NEWLINE CONVENTION</a>
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<li><a name="TOC18" href="#SEC18">WHAT \R MATCHES</a>
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<li><a name="TOC19" href="#SEC19">LOOKAHEAD AND LOOKBEHIND ASSERTIONS</a>
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<li><a name="TOC20" href="#SEC20">BACKREFERENCES</a>
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<li><a name="TOC21" href="#SEC21">SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)</a>
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<li><a name="TOC22" href="#SEC22">CONDITIONAL PATTERNS</a>
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<li><a name="TOC23" href="#SEC23">BACKTRACKING CONTROL</a>
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<li><a name="TOC24" href="#SEC24">CALLOUTS</a>
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<li><a name="TOC25" href="#SEC25">SEE ALSO</a>
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<li><a name="TOC26" href="#SEC26">AUTHOR</a>
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<li><a name="TOC27" href="#SEC27">REVISION</a>
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</ul>
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<br><a name="SEC1" href="#TOC1">PCRE2 REGULAR EXPRESSION SYNTAX SUMMARY</a><br>
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<P>
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The full syntax and semantics of the regular expressions that are supported by
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PCRE2 are described in the
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<a href="pcre2pattern.html"><b>pcre2pattern</b></a>
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documentation. This document contains a quick-reference summary of the syntax.
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</P>
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<br><a name="SEC2" href="#TOC1">QUOTING</a><br>
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<P>
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<pre>
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\x where x is non-alphanumeric is a literal x
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\Q...\E treat enclosed characters as literal
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</PRE>
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</P>
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<br><a name="SEC3" href="#TOC1">CHARACTERS</a><br>
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<P>
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<pre>
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\a alarm, that is, the BEL character (hex 07)
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\cx "control-x", where x is any ASCII character
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\e escape (hex 1B)
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\f form feed (hex 0C)
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\n newline (hex 0A)
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\r carriage return (hex 0D)
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\t tab (hex 09)
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\0dd character with octal code 0dd
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\ddd character with octal code ddd, or backreference
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\o{ddd..} character with octal code ddd..
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\xhh character with hex code hh
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\x{hhh..} character with hex code hhh..
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</pre>
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Note that \0dd is always an octal code, and that \8 and \9 are the literal
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characters "8" and "9".
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</P>
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<br><a name="SEC4" href="#TOC1">CHARACTER TYPES</a><br>
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<P>
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<pre>
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. any character except newline;
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in dotall mode, any character whatsoever
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\C one data unit, even in UTF mode (best avoided)
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\d a decimal digit
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\D a character that is not a decimal digit
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\h a horizontal white space character
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\H a character that is not a horizontal white space character
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\N a character that is not a newline
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\p{<i>xx</i>} a character with the <i>xx</i> property
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\P{<i>xx</i>} a character without the <i>xx</i> property
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\R a newline sequence
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\s a white space character
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\S a character that is not a white space character
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\v a vertical white space character
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\V a character that is not a vertical white space character
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\w a "word" character
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\W a "non-word" character
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\X a Unicode extended grapheme cluster
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</pre>
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By default, \d, \s, and \w match only ASCII characters, even in UTF-8 mode
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or in the 16-bit and 32-bit libraries. However, if locale-specific matching is
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happening, \s and \w may also match characters with code points in the range
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128-255. If the PCRE2_UCP option is set, the behaviour of these escape
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sequences is changed to use Unicode properties and they match many more
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characters.
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</P>
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<br><a name="SEC5" href="#TOC1">GENERAL CATEGORY PROPERTIES FOR \p and \P</a><br>
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<P>
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<pre>
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C Other
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Cc Control
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Cf Format
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Cn Unassigned
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Co Private use
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Cs Surrogate
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L Letter
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Ll Lower case letter
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Lm Modifier letter
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Lo Other letter
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Lt Title case letter
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Lu Upper case letter
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L& Ll, Lu, or Lt
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M Mark
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Mc Spacing mark
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Me Enclosing mark
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Mn Non-spacing mark
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N Number
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Nd Decimal number
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Nl Letter number
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No Other number
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P Punctuation
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Pc Connector punctuation
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Pd Dash punctuation
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Pe Close punctuation
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Pf Final punctuation
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Pi Initial punctuation
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Po Other punctuation
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Ps Open punctuation
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S Symbol
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Sc Currency symbol
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Sk Modifier symbol
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Sm Mathematical symbol
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So Other symbol
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Z Separator
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Zl Line separator
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Zp Paragraph separator
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Zs Space separator
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</PRE>
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</P>
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<br><a name="SEC6" href="#TOC1">PCRE2 SPECIAL CATEGORY PROPERTIES FOR \p and \P</a><br>
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<P>
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<pre>
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Xan Alphanumeric: union of properties L and N
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Xps POSIX space: property Z or tab, NL, VT, FF, CR
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Xsp Perl space: property Z or tab, NL, VT, FF, CR
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Xuc Univerally-named character: one that can be
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represented by a Universal Character Name
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Xwd Perl word: property Xan or underscore
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</pre>
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Perl and POSIX space are now the same. Perl added VT to its space character set
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at release 5.18.
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</P>
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<br><a name="SEC7" href="#TOC1">SCRIPT NAMES FOR \p AND \P</a><br>
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<P>
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Arabic,
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Armenian,
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Avestan,
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Balinese,
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Bamum,
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Bassa_Vah,
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Batak,
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Bengali,
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Bopomofo,
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Brahmi,
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Braille,
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Buginese,
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Buhid,
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Canadian_Aboriginal,
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Carian,
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Caucasian_Albanian,
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Chakma,
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Cham,
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Cherokee,
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Common,
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Coptic,
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Cuneiform,
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Cypriot,
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Cyrillic,
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Deseret,
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Devanagari,
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Duployan,
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Egyptian_Hieroglyphs,
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Elbasan,
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Ethiopic,
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Georgian,
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Glagolitic,
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Gothic,
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Grantha,
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Greek,
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Gujarati,
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Gurmukhi,
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Han,
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Hangul,
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Hanunoo,
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Hebrew,
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Hiragana,
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Imperial_Aramaic,
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Inherited,
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Inscriptional_Pahlavi,
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Inscriptional_Parthian,
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Javanese,
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Kaithi,
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Kannada,
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Katakana,
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Kayah_Li,
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Kharoshthi,
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Khmer,
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Khojki,
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Khudawadi,
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Lao,
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Latin,
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Lepcha,
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Limbu,
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Linear_A,
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Linear_B,
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Lisu,
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Lycian,
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Lydian,
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Mahajani,
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Malayalam,
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Mandaic,
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Manichaean,
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Meetei_Mayek,
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Mende_Kikakui,
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Meroitic_Cursive,
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Meroitic_Hieroglyphs,
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Miao,
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Modi,
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Mongolian,
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Mro,
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Myanmar,
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Nabataean,
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New_Tai_Lue,
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Nko,
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Ogham,
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Ol_Chiki,
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Old_Italic,
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Old_North_Arabian,
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Old_Permic,
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Old_Persian,
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Old_South_Arabian,
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Old_Turkic,
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Oriya,
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Osmanya,
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Pahawh_Hmong,
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Palmyrene,
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Pau_Cin_Hau,
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Phags_Pa,
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Phoenician,
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Psalter_Pahlavi,
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Rejang,
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Runic,
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Samaritan,
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Saurashtra,
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Sharada,
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Shavian,
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Siddham,
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Sinhala,
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Sora_Sompeng,
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Sundanese,
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Syloti_Nagri,
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Syriac,
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Tagalog,
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Tagbanwa,
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Tai_Le,
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Tai_Tham,
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Tai_Viet,
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Takri,
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Tamil,
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Telugu,
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Thaana,
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Thai,
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Tibetan,
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Tifinagh,
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Tirhuta,
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Ugaritic,
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Vai,
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Warang_Citi,
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Yi.
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</P>
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<br><a name="SEC8" href="#TOC1">CHARACTER CLASSES</a><br>
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<P>
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<pre>
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[...] positive character class
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[^...] negative character class
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[x-y] range (can be used for hex characters)
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[[:xxx:]] positive POSIX named set
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[[:^xxx:]] negative POSIX named set
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alnum alphanumeric
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alpha alphabetic
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ascii 0-127
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blank space or tab
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cntrl control character
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digit decimal digit
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graph printing, excluding space
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lower lower case letter
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print printing, including space
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punct printing, excluding alphanumeric
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space white space
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upper upper case letter
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word same as \w
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xdigit hexadecimal digit
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</pre>
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In PCRE2, POSIX character set names recognize only ASCII characters by default,
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but some of them use Unicode properties if PCRE2_UCP is set. You can use
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\Q...\E inside a character class.
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</P>
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<br><a name="SEC9" href="#TOC1">QUANTIFIERS</a><br>
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<P>
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<pre>
|
|
|
|
|
? 0 or 1, greedy
|
|
|
|
|
?+ 0 or 1, possessive
|
|
|
|
|
?? 0 or 1, lazy
|
|
|
|
|
* 0 or more, greedy
|
|
|
|
|
*+ 0 or more, possessive
|
|
|
|
|
*? 0 or more, lazy
|
|
|
|
|
+ 1 or more, greedy
|
|
|
|
|
++ 1 or more, possessive
|
|
|
|
|
+? 1 or more, lazy
|
|
|
|
|
{n} exactly n
|
|
|
|
|
{n,m} at least n, no more than m, greedy
|
|
|
|
|
{n,m}+ at least n, no more than m, possessive
|
|
|
|
|
{n,m}? at least n, no more than m, lazy
|
|
|
|
|
{n,} n or more, greedy
|
|
|
|
|
{n,}+ n or more, possessive
|
|
|
|
|
{n,}? n or more, lazy
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC10" href="#TOC1">ANCHORS AND SIMPLE ASSERTIONS</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
\b word boundary
|
|
|
|
|
\B not a word boundary
|
|
|
|
|
^ start of subject
|
|
|
|
|
also after internal newline in multiline mode
|
|
|
|
|
\A start of subject
|
|
|
|
|
$ end of subject
|
|
|
|
|
also before newline at end of subject
|
|
|
|
|
also before internal newline in multiline mode
|
|
|
|
|
\Z end of subject
|
|
|
|
|
also before newline at end of subject
|
|
|
|
|
\z end of subject
|
|
|
|
|
\G first matching position in subject
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC11" href="#TOC1">MATCH POINT RESET</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
\K reset start of match
|
|
|
|
|
</pre>
|
|
|
|
|
\K is honoured in positive assertions, but ignored in negative ones.
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC12" href="#TOC1">ALTERNATION</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
expr|expr|expr...
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC13" href="#TOC1">CAPTURING</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
(...) capturing group
|
|
|
|
|
(?<name>...) named capturing group (Perl)
|
|
|
|
|
(?'name'...) named capturing group (Perl)
|
|
|
|
|
(?P<name>...) named capturing group (Python)
|
|
|
|
|
(?:...) non-capturing group
|
|
|
|
|
(?|...) non-capturing group; reset group numbers for
|
|
|
|
|
capturing groups in each alternative
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC14" href="#TOC1">ATOMIC GROUPS</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
(?>...) atomic, non-capturing group
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC15" href="#TOC1">COMMENT</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
(?#....) comment (not nestable)
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC16" href="#TOC1">OPTION SETTING</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
(?i) caseless
|
|
|
|
|
(?J) allow duplicate names
|
|
|
|
|
(?m) multiline
|
|
|
|
|
(?s) single line (dotall)
|
|
|
|
|
(?U) default ungreedy (lazy)
|
|
|
|
|
(?x) extended (ignore white space)
|
|
|
|
|
(?-...) unset option(s)
|
|
|
|
|
</pre>
|
|
|
|
|
The following are recognized only at the very start of a pattern or after one
|
|
|
|
|
of the newline or \R options with similar syntax. More than one of them may
|
|
|
|
|
appear.
|
|
|
|
|
<pre>
|
|
|
|
|
(*LIMIT_MATCH=d) set the match limit to d (decimal number)
|
|
|
|
|
(*LIMIT_RECURSION=d) set the recursion limit to d (decimal number)
|
|
|
|
|
(*NOTEMPTY) set PCRE2_NOTEMPTY when matching
|
2014-10-20 19:28:49 +02:00
|
|
|
(*NOTEMPTY_ATSTART) set PCRE2_NOTEMPTY_ATSTART when matching
|
2014-10-20 18:48:14 +02:00
|
|
|
(*NO_AUTO_POSSESS) no auto-possessification (PCRE2_NO_AUTO_POSSESS)
|
|
|
|
|
(*NO_START_OPT) no start-match optimization (PCRE2_NO_START_OPTIMIZE)
|
|
|
|
|
(*UTF) set appropriate UTF mode for the library in use
|
|
|
|
|
(*UCP) set PCRE2_UCP (use Unicode properties for \d etc)
|
|
|
|
|
</pre>
|
|
|
|
|
Note that LIMIT_MATCH and LIMIT_RECURSION can only reduce the value of the
|
2014-11-23 19:38:38 +01:00
|
|
|
limits set by the caller of pcre2_match(), not increase them.
|
2014-10-20 18:48:14 +02:00
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC17" href="#TOC1">NEWLINE CONVENTION</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
These are recognized only at the very start of the pattern or after option
|
|
|
|
|
settings with a similar syntax.
|
|
|
|
|
<pre>
|
|
|
|
|
(*CR) carriage return only
|
|
|
|
|
(*LF) linefeed only
|
|
|
|
|
(*CRLF) carriage return followed by linefeed
|
|
|
|
|
(*ANYCRLF) all three of the above
|
|
|
|
|
(*ANY) any Unicode newline sequence
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC18" href="#TOC1">WHAT \R MATCHES</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
These are recognized only at the very start of the pattern or after option
|
|
|
|
|
setting with a similar syntax.
|
|
|
|
|
<pre>
|
|
|
|
|
(*BSR_ANYCRLF) CR, LF, or CRLF
|
|
|
|
|
(*BSR_UNICODE) any Unicode newline sequence
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC19" href="#TOC1">LOOKAHEAD AND LOOKBEHIND ASSERTIONS</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
(?=...) positive look ahead
|
|
|
|
|
(?!...) negative look ahead
|
|
|
|
|
(?<=...) positive look behind
|
|
|
|
|
(?<!...) negative look behind
|
|
|
|
|
</pre>
|
|
|
|
|
Each top-level branch of a look behind must be of a fixed length.
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC20" href="#TOC1">BACKREFERENCES</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
\n reference by number (can be ambiguous)
|
|
|
|
|
\gn reference by number
|
|
|
|
|
\g{n} reference by number
|
|
|
|
|
\g{-n} relative reference by number
|
|
|
|
|
\k<name> reference by name (Perl)
|
|
|
|
|
\k'name' reference by name (Perl)
|
|
|
|
|
\g{name} reference by name (Perl)
|
|
|
|
|
\k{name} reference by name (.NET)
|
|
|
|
|
(?P=name) reference by name (Python)
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC21" href="#TOC1">SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
(?R) recurse whole pattern
|
|
|
|
|
(?n) call subpattern by absolute number
|
|
|
|
|
(?+n) call subpattern by relative number
|
|
|
|
|
(?-n) call subpattern by relative number
|
|
|
|
|
(?&name) call subpattern by name (Perl)
|
|
|
|
|
(?P>name) call subpattern by name (Python)
|
|
|
|
|
\g<name> call subpattern by name (Oniguruma)
|
|
|
|
|
\g'name' call subpattern by name (Oniguruma)
|
|
|
|
|
\g<n> call subpattern by absolute number (Oniguruma)
|
|
|
|
|
\g'n' call subpattern by absolute number (Oniguruma)
|
|
|
|
|
\g<+n> call subpattern by relative number (PCRE2 extension)
|
|
|
|
|
\g'+n' call subpattern by relative number (PCRE2 extension)
|
|
|
|
|
\g<-n> call subpattern by relative number (PCRE2 extension)
|
|
|
|
|
\g'-n' call subpattern by relative number (PCRE2 extension)
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC22" href="#TOC1">CONDITIONAL PATTERNS</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
(?(condition)yes-pattern)
|
|
|
|
|
(?(condition)yes-pattern|no-pattern)
|
|
|
|
|
|
2014-11-14 19:41:20 +01:00
|
|
|
(?(n) absolute reference condition
|
|
|
|
|
(?(+n) relative reference condition
|
|
|
|
|
(?(-n) relative reference condition
|
|
|
|
|
(?(<name>) named reference condition (Perl)
|
|
|
|
|
(?('name') named reference condition (Perl)
|
|
|
|
|
(?(name) named reference condition (PCRE2)
|
|
|
|
|
(?(R) overall recursion condition
|
|
|
|
|
(?(Rn) specific group recursion condition
|
|
|
|
|
(?(R&name) specific recursion condition
|
|
|
|
|
(?(DEFINE) define subpattern for reference
|
|
|
|
|
(?(VERSION[>]=n.m) test PCRE2 version
|
|
|
|
|
(?(assert) assertion condition
|
2014-10-20 18:48:14 +02:00
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC23" href="#TOC1">BACKTRACKING CONTROL</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
The following act immediately they are reached:
|
|
|
|
|
<pre>
|
|
|
|
|
(*ACCEPT) force successful match
|
|
|
|
|
(*FAIL) force backtrack; synonym (*F)
|
|
|
|
|
(*MARK:NAME) set name to be passed back; synonym (*:NAME)
|
|
|
|
|
</pre>
|
|
|
|
|
The following act only when a subsequent match failure causes a backtrack to
|
|
|
|
|
reach them. They all force a match failure, but they differ in what happens
|
|
|
|
|
afterwards. Those that advance the start-of-match point do so only if the
|
|
|
|
|
pattern is not anchored.
|
|
|
|
|
<pre>
|
|
|
|
|
(*COMMIT) overall failure, no advance of starting point
|
|
|
|
|
(*PRUNE) advance to next starting character
|
|
|
|
|
(*PRUNE:NAME) equivalent to (*MARK:NAME)(*PRUNE)
|
|
|
|
|
(*SKIP) advance to current matching position
|
|
|
|
|
(*SKIP:NAME) advance to position corresponding to an earlier
|
|
|
|
|
(*MARK:NAME); if not found, the (*SKIP) is ignored
|
|
|
|
|
(*THEN) local failure, backtrack to next alternation
|
|
|
|
|
(*THEN:NAME) equivalent to (*MARK:NAME)(*THEN)
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC24" href="#TOC1">CALLOUTS</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
(?C) callout
|
|
|
|
|
(?Cn) callout with data n
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC25" href="#TOC1">SEE ALSO</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<b>pcre2pattern</b>(3), <b>pcre2api</b>(3), <b>pcre2callout</b>(3),
|
|
|
|
|
<b>pcre2matching</b>(3), <b>pcre2</b>(3).
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC26" href="#TOC1">AUTHOR</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
Philip Hazel
|
|
|
|
|
<br>
|
|
|
|
|
University Computing Service
|
|
|
|
|
<br>
|
2014-11-21 17:45:06 +01:00
|
|
|
Cambridge, England.
|
2014-10-20 18:48:14 +02:00
|
|
|
<br>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC27" href="#TOC1">REVISION</a><br>
|
|
|
|
|
<P>
|
2014-11-23 19:38:38 +01:00
|
|
|
Last updated: 23 November 2014
|
2014-10-20 18:48:14 +02:00
|
|
|
<br>
|
|
|
|
|
Copyright © 1997-2014 University of Cambridge.
|
|
|
|
|
<br>
|
|
|
|
|
<p>
|
|
|
|
|
Return to the <a href="index.html">PCRE2 index page</a>.
|
|
|
|
|
</p>
|
