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">ESCAPED 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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2018-06-28 18:56:56 +02:00
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<li><a name="TOC11" href="#SEC11">REPORTED MATCH POINT SETTING</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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2018-10-12 19:02:34 +02:00
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<li><a name="TOC20" href="#SEC20">SCRIPT RUNS</a>
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<li><a name="TOC21" href="#SEC21">BACKREFERENCES</a>
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<li><a name="TOC22" href="#SEC22">SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)</a>
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<li><a name="TOC23" href="#SEC23">CONDITIONAL PATTERNS</a>
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<li><a name="TOC24" href="#SEC24">BACKTRACKING CONTROL</a>
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<li><a name="TOC25" href="#SEC25">CALLOUTS</a>
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<li><a name="TOC26" href="#SEC26">SEE ALSO</a>
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<li><a name="TOC27" href="#SEC27">AUTHOR</a>
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<li><a name="TOC28" href="#SEC28">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">ESCAPED CHARACTERS</a><br>
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<P>
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This table applies to ASCII and Unicode environments.
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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 printing 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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\U "U" if PCRE2_ALT_BSUX is set (otherwise is an error)
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\N{U+hh..} character with Unicode code point hh.. (Unicode mode only)
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\uhhhh character with hex code hhhh (if PCRE2_ALT_BSUX is set)
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\xhh character with hex code hh
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\x{hh..} character with hex code hh..
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</pre>
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Note that \0dd is always an octal code. The treatment of backslash followed by
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a non-zero digit is complicated; for details see the section
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<a href="pcre2pattern.html#digitsafterbackslash">"Non-printing characters"</a>
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in the
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<a href="pcre2pattern.html"><b>pcre2pattern</b></a>
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documentation, where details of escape processing in EBCDIC environments are
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also given. \N{U+hh..} is synonymous with \x{hh..} in PCRE2 but is not
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supported in EBCDIC environments. Note that \N not followed by an opening
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curly bracket has a different meaning (see below).
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</P>
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<P>
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When \x is not followed by {, from zero to two hexadecimal digits are read,
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but if PCRE2_ALT_BSUX is set, \x must be followed by two hexadecimal digits to
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be recognized as a hexadecimal escape; otherwise it matches a literal "x".
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Likewise, if \u (in ALT_BSUX mode) is not followed by four hexadecimal digits,
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it matches a literal "u".
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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 code 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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2015-10-17 15:50:56 +02:00
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\C is dangerous because it may leave the current matching point in the middle
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of a UTF-8 or UTF-16 character. The application can lock out the use of \C by
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2015-12-17 19:44:06 +01:00
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setting the PCRE2_NEVER_BACKSLASH_C option. It is also possible to build PCRE2
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with the use of \C permanently disabled.
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2015-06-18 18:39:25 +02:00
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</P>
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<P>
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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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2018-07-07 18:10:29 +02:00
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Adlam,
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2015-08-30 19:47:36 +02:00
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Ahom,
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Anatolian_Hieroglyphs,
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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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Bhaiksuki,
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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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Dogra,
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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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Gunjala_Gondi,
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Gurmukhi,
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Han,
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Hangul,
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Hanifi_Rohingya,
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Hanunoo,
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Hatran,
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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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Makasar,
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Malayalam,
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Mandaic,
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Manichaean,
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Marchen,
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Masaram_Gondi,
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Medefaidrin,
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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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Multani,
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Myanmar,
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Nabataean,
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New_Tai_Lue,
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|
Newa,
|
2014-10-20 18:48:14 +02:00
|
|
|
Nko,
|
2018-07-07 18:10:29 +02:00
|
|
|
Nushu,
|
2014-10-20 18:48:14 +02:00
|
|
|
Ogham,
|
|
|
|
|
Ol_Chiki,
|
2015-08-30 19:47:36 +02:00
|
|
|
Old_Hungarian,
|
2014-10-20 18:48:14 +02:00
|
|
|
Old_Italic,
|
|
|
|
|
Old_North_Arabian,
|
|
|
|
|
Old_Permic,
|
|
|
|
|
Old_Persian,
|
2018-07-07 18:10:29 +02:00
|
|
|
Old_Sogdian,
|
2014-10-20 18:48:14 +02:00
|
|
|
Old_South_Arabian,
|
|
|
|
|
Old_Turkic,
|
|
|
|
|
Oriya,
|
2018-07-07 18:10:29 +02:00
|
|
|
Osage,
|
2014-10-20 18:48:14 +02:00
|
|
|
Osmanya,
|
|
|
|
|
Pahawh_Hmong,
|
|
|
|
|
Palmyrene,
|
|
|
|
|
Pau_Cin_Hau,
|
|
|
|
|
Phags_Pa,
|
|
|
|
|
Phoenician,
|
|
|
|
|
Psalter_Pahlavi,
|
|
|
|
|
Rejang,
|
|
|
|
|
Runic,
|
|
|
|
|
Samaritan,
|
|
|
|
|
Saurashtra,
|
|
|
|
|
Sharada,
|
|
|
|
|
Shavian,
|
|
|
|
|
Siddham,
|
2015-08-30 19:47:36 +02:00
|
|
|
SignWriting,
|
2014-10-20 18:48:14 +02:00
|
|
|
Sinhala,
|
2018-07-07 18:10:29 +02:00
|
|
|
Sogdian,
|
2014-10-20 18:48:14 +02:00
|
|
|
Sora_Sompeng,
|
2018-07-07 18:10:29 +02:00
|
|
|
Soyombo,
|
2014-10-20 18:48:14 +02:00
|
|
|
Sundanese,
|
|
|
|
|
Syloti_Nagri,
|
|
|
|
|
Syriac,
|
|
|
|
|
Tagalog,
|
|
|
|
|
Tagbanwa,
|
|
|
|
|
Tai_Le,
|
|
|
|
|
Tai_Tham,
|
|
|
|
|
Tai_Viet,
|
|
|
|
|
Takri,
|
|
|
|
|
Tamil,
|
2018-07-07 18:10:29 +02:00
|
|
|
Tangut,
|
2014-10-20 18:48:14 +02:00
|
|
|
Telugu,
|
|
|
|
|
Thaana,
|
|
|
|
|
Thai,
|
|
|
|
|
Tibetan,
|
|
|
|
|
Tifinagh,
|
|
|
|
|
Tirhuta,
|
|
|
|
|
Ugaritic,
|
|
|
|
|
Vai,
|
|
|
|
|
Warang_Citi,
|
2018-07-07 18:10:29 +02:00
|
|
|
Yi,
|
|
|
|
|
Zanabazar_Square.
|
2014-10-20 18:48:14 +02:00
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC8" href="#TOC1">CHARACTER CLASSES</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
[...] positive character class
|
|
|
|
|
[^...] negative character class
|
|
|
|
|
[x-y] range (can be used for hex characters)
|
|
|
|
|
[[:xxx:]] positive POSIX named set
|
|
|
|
|
[[:^xxx:]] negative POSIX named set
|
|
|
|
|
|
|
|
|
|
alnum alphanumeric
|
|
|
|
|
alpha alphabetic
|
|
|
|
|
ascii 0-127
|
|
|
|
|
blank space or tab
|
|
|
|
|
cntrl control character
|
|
|
|
|
digit decimal digit
|
|
|
|
|
graph printing, excluding space
|
|
|
|
|
lower lower case letter
|
|
|
|
|
print printing, including space
|
|
|
|
|
punct printing, excluding alphanumeric
|
|
|
|
|
space white space
|
|
|
|
|
upper upper case letter
|
|
|
|
|
word same as \w
|
|
|
|
|
xdigit hexadecimal digit
|
|
|
|
|
</pre>
|
|
|
|
|
In PCRE2, POSIX character set names recognize only ASCII characters by default,
|
|
|
|
|
but some of them use Unicode properties if PCRE2_UCP is set. You can use
|
|
|
|
|
\Q...\E inside a character class.
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC9" href="#TOC1">QUANTIFIERS</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<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
|
2015-06-18 18:39:25 +02:00
|
|
|
also after an internal newline in multiline mode
|
|
|
|
|
(after any newline if PCRE2_ALT_CIRCUMFLEX is set)
|
2014-10-20 18:48:14 +02:00
|
|
|
\A start of subject
|
|
|
|
|
$ end of subject
|
2015-06-18 18:39:25 +02:00
|
|
|
also before newline at end of subject
|
|
|
|
|
also before internal newline in multiline mode
|
2014-10-20 18:48:14 +02:00
|
|
|
\Z end of subject
|
2015-06-18 18:39:25 +02:00
|
|
|
also before newline at end of subject
|
2014-10-20 18:48:14 +02:00
|
|
|
\z end of subject
|
|
|
|
|
\G first matching position in subject
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
2018-06-28 18:56:56 +02:00
|
|
|
<br><a name="SEC11" href="#TOC1">REPORTED MATCH POINT SETTING</a><br>
|
2014-10-20 18:48:14 +02:00
|
|
|
<P>
|
|
|
|
|
<pre>
|
2018-06-28 18:56:56 +02:00
|
|
|
\K set reported start of match
|
2014-10-20 18:48:14 +02:00
|
|
|
</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
|
2018-09-24 18:23:53 +02:00
|
|
|
(*atomic:...) atomic, non-capturing group
|
2014-10-20 18:48:14 +02:00
|
|
|
</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>
|
2018-08-13 13:57:09 +02:00
|
|
|
Changes of these options within a group are automatically cancelled at the end
|
2018-08-03 11:38:36 +02:00
|
|
|
of the group.
|
2014-10-20 18:48:14 +02:00
|
|
|
<pre>
|
|
|
|
|
(?i) caseless
|
|
|
|
|
(?J) allow duplicate names
|
|
|
|
|
(?m) multiline
|
2017-07-19 18:04:15 +02:00
|
|
|
(?n) no auto capture
|
2014-10-20 18:48:14 +02:00
|
|
|
(?s) single line (dotall)
|
|
|
|
|
(?U) default ungreedy (lazy)
|
2017-04-18 14:32:52 +02:00
|
|
|
(?x) extended: ignore white space except in classes
|
2017-07-19 18:04:15 +02:00
|
|
|
(?xx) as (?x) but also ignore space and tab in classes
|
2014-10-20 18:48:14 +02:00
|
|
|
(?-...) unset option(s)
|
2018-08-13 13:57:09 +02:00
|
|
|
(?^) unset imnsx options
|
2014-10-20 18:48:14 +02:00
|
|
|
</pre>
|
2018-07-28 18:23:24 +02:00
|
|
|
Unsetting x or xx unsets both. Several options may be set at once, and a
|
|
|
|
|
mixture of setting and unsetting such as (?i-x) is allowed, but there may be
|
|
|
|
|
only one hyphen. Setting (but no unsetting) is allowed after (?^ for example
|
2018-08-13 13:57:09 +02:00
|
|
|
(?^in). An option setting may appear at the start of a non-capturing group, for
|
2018-07-28 18:23:24 +02:00
|
|
|
example (?i:...).
|
|
|
|
|
</P>
|
|
|
|
|
<P>
|
2014-10-20 18:48:14 +02:00
|
|
|
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
|
2017-06-17 13:40:17 +02:00
|
|
|
appear. For the first three, d is a decimal number.
|
2014-10-20 18:48:14 +02:00
|
|
|
<pre>
|
2017-06-17 13:40:17 +02:00
|
|
|
(*LIMIT_DEPTH=d) set the backtracking limit to d
|
2018-06-17 16:13:28 +02:00
|
|
|
(*LIMIT_HEAP=d) set the heap size limit to d * 1024 bytes
|
2017-06-17 13:40:17 +02:00
|
|
|
(*LIMIT_MATCH=d) set the match limit to d
|
|
|
|
|
(*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)
|
2015-01-02 18:09:16 +01:00
|
|
|
(*NO_DOTSTAR_ANCHOR) no .* anchoring (PCRE2_NO_DOTSTAR_ANCHOR)
|
2015-02-20 12:20:40 +01:00
|
|
|
(*NO_JIT) disable JIT optimization
|
2014-10-20 18:48:14 +02:00
|
|
|
(*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>
|
2017-06-17 13:40:17 +02:00
|
|
|
Note that LIMIT_DEPTH, LIMIT_HEAP, and LIMIT_MATCH can only reduce the value of
|
|
|
|
|
the limits set by the caller of <b>pcre2_match()</b> or <b>pcre2_dfa_match()</b>,
|
|
|
|
|
not increase them. LIMIT_RECURSION is an obsolete synonym for LIMIT_DEPTH. The
|
2017-04-01 11:38:58 +02:00
|
|
|
application can lock out the use of (*UTF) and (*UCP) by setting the
|
|
|
|
|
PCRE2_NEVER_UTF or PCRE2_NEVER_UCP options, respectively, at compile time.
|
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
|
2017-05-26 19:14:36 +02:00
|
|
|
(*NUL) the NUL character (binary zero)
|
2014-10-20 18:48:14 +02:00
|
|
|
</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>
|
2018-09-24 18:23:53 +02:00
|
|
|
(?=...) )
|
|
|
|
|
(*pla:...) ) positive lookahead
|
|
|
|
|
(*positive_lookahead:...) )
|
|
|
|
|
|
|
|
|
|
(?!...) )
|
|
|
|
|
(*nla:...) ) negative lookahead
|
|
|
|
|
(*negative_lookahead:...) )
|
|
|
|
|
|
|
|
|
|
(?<=...) )
|
|
|
|
|
(*plb:...) ) positive lookbehind
|
|
|
|
|
(*positive_lookbehind:...) )
|
|
|
|
|
|
|
|
|
|
(?<!...) )
|
|
|
|
|
(*nlb:...) ) negative lookbehind
|
|
|
|
|
(*negative_lookbehind:...) )
|
2014-10-20 18:48:14 +02:00
|
|
|
</pre>
|
2018-09-24 18:23:53 +02:00
|
|
|
Each top-level branch of a lookbehind must be of a fixed length.
|
2014-10-20 18:48:14 +02:00
|
|
|
</P>
|
2018-10-12 19:02:34 +02:00
|
|
|
<br><a name="SEC20" href="#TOC1">SCRIPT RUNS</a><br>
|
|
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
(*script_run:...) ) script run, can be backtracked into
|
|
|
|
|
(*sr:...) )
|
|
|
|
|
|
|
|
|
|
(*atomic_script_run:...) ) atomic script run
|
|
|
|
|
(*asr:...) )
|
|
|
|
|
</PRE>
|
|
|
|
|
</P>
|
|
|
|
|
<br><a name="SEC21" href="#TOC1">BACKREFERENCES</a><br>
|
2014-10-20 18:48:14 +02:00
|
|
|
<P>
|
|
|
|
|
<pre>
|
|
|
|
|
\n reference by number (can be ambiguous)
|
|
|
|
|
\gn reference by number
|
|
|
|
|
\g{n} reference by number
|
2016-11-22 16:37:02 +01:00
|
|
|
\g+n relative reference by number (PCRE2 extension)
|
|
|
|
|
\g-n relative reference by number
|
2017-01-16 18:40:47 +01:00
|
|
|
\g{+n} relative reference by number (PCRE2 extension)
|
2014-10-20 18:48:14 +02:00
|
|
|
\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>
|
2018-10-12 19:02:34 +02:00
|
|
|
<br><a name="SEC22" href="#TOC1">SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)</a><br>
|
2014-10-20 18:48:14 +02:00
|
|
|
<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)
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\g'name' call subpattern by name (Oniguruma)
|
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|
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\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)
|
|
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|
|
\g'+n' call subpattern by relative number (PCRE2 extension)
|
|
|
|
|
\g<-n> call subpattern by relative number (PCRE2 extension)
|
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|
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\g'-n' call subpattern by relative number (PCRE2 extension)
|
|
|
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|
</PRE>
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</P>
|
2018-10-12 19:02:34 +02:00
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<br><a name="SEC23" href="#TOC1">CONDITIONAL PATTERNS</a><br>
|
2014-10-20 18:48:14 +02:00
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<P>
|
|
|
|
|
<pre>
|
|
|
|
|
(?(condition)yes-pattern)
|
|
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|
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(?(condition)yes-pattern|no-pattern)
|
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|
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|
2014-11-14 19:41:20 +01:00
|
|
|
(?(n) absolute reference condition
|
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|
(?(+n) relative reference condition
|
|
|
|
|
(?(-n) relative reference condition
|
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|
|
|
(?(<name>) named reference condition (Perl)
|
|
|
|
|
(?('name') named reference condition (Perl)
|
2016-11-22 16:37:02 +01:00
|
|
|
(?(name) named reference condition (PCRE2, deprecated)
|
2014-11-14 19:41:20 +01:00
|
|
|
(?(R) overall recursion condition
|
2016-11-22 16:37:02 +01:00
|
|
|
(?(Rn) specific numbered group recursion condition
|
|
|
|
|
(?(R&name) specific named group recursion condition
|
2014-11-14 19:41:20 +01:00
|
|
|
(?(DEFINE) define subpattern for reference
|
|
|
|
|
(?(VERSION[>]=n.m) test PCRE2 version
|
|
|
|
|
(?(assert) assertion condition
|
2016-11-22 16:37:02 +01:00
|
|
|
</pre>
|
2017-01-16 18:40:47 +01:00
|
|
|
Note the ambiguity of (?(R) and (?(Rn) which might be named reference
|
2016-11-22 16:37:02 +01:00
|
|
|
conditions or recursion tests. Such a condition is interpreted as a reference
|
|
|
|
|
condition if the relevant named group exists.
|
2014-10-20 18:48:14 +02:00
|
|
|
</P>
|
2018-10-12 19:02:34 +02:00
|
|
|
<br><a name="SEC24" href="#TOC1">BACKTRACKING CONTROL</a><br>
|
2014-10-20 18:48:14 +02:00
|
|
|
<P>
|
2018-07-21 16:34:51 +02:00
|
|
|
All backtracking control verbs may be in the form (*VERB:NAME). For (*MARK) the
|
|
|
|
|
name is mandatory, for the others it is optional. (*SKIP) changes its behaviour
|
|
|
|
|
if :NAME is present. The others just set a name for passing back to the caller,
|
|
|
|
|
but this is not a name that (*SKIP) can see. The following act immediately they
|
|
|
|
|
are reached:
|
2014-10-20 18:48:14 +02:00
|
|
|
<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
|
|
|
|
|
(*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
|
2018-07-21 16:34:51 +02:00
|
|
|
</pre>
|
2018-08-13 13:57:09 +02:00
|
|
|
The effect of one of these verbs in a group called as a subroutine is confined
|
|
|
|
|
to the subroutine call.
|
2014-10-20 18:48:14 +02:00
|
|
|
</P>
|
2018-10-12 19:02:34 +02:00
|
|
|
<br><a name="SEC25" href="#TOC1">CALLOUTS</a><br>
|
2014-10-20 18:48:14 +02:00
|
|
|
<P>
|
|
|
|
|
<pre>
|
2015-03-23 16:52:08 +01:00
|
|
|
(?C) callout (assumed number 0)
|
|
|
|
|
(?Cn) callout with numerical data n
|
|
|
|
|
(?C"text") callout with string data
|
|
|
|
|
</pre>
|
2015-06-18 18:39:25 +02:00
|
|
|
The allowed string delimiters are ` ' " ^ % # $ (which are the same for the
|
|
|
|
|
start and the end), and the starting delimiter { matched with the ending
|
|
|
|
|
delimiter }. To encode the ending delimiter within the string, double it.
|
2014-10-20 18:48:14 +02:00
|
|
|
</P>
|
2018-10-12 19:02:34 +02:00
|
|
|
<br><a name="SEC26" href="#TOC1">SEE ALSO</a><br>
|
2014-10-20 18:48:14 +02:00
|
|
|
<P>
|
|
|
|
|
<b>pcre2pattern</b>(3), <b>pcre2api</b>(3), <b>pcre2callout</b>(3),
|
|
|
|
|
<b>pcre2matching</b>(3), <b>pcre2</b>(3).
|
|
|
|
|
</P>
|
2018-10-12 19:02:34 +02:00
|
|
|
<br><a name="SEC27" href="#TOC1">AUTHOR</a><br>
|
2014-10-20 18:48:14 +02:00
|
|
|
<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>
|
2018-10-12 19:02:34 +02:00
|
|
|
<br><a name="SEC28" href="#TOC1">REVISION</a><br>
|
2014-10-20 18:48:14 +02:00
|
|
|
<P>
|
2018-10-12 19:02:34 +02:00
|
|
|
Last updated: 10 October 2018
|
2014-10-20 18:48:14 +02:00
|
|
|
<br>
|
2018-06-28 18:56:56 +02:00
|
|
|
Copyright © 1997-2018 University of Cambridge.
|
2014-10-20 18:48:14 +02:00
|
|
|
<br>
|
|
|
|
|
<p>
|
|
|
|
|
Return to the <a href="index.html">PCRE2 index page</a>.
|
|
|
|
|
</p>
|
