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revision 512 by ph10, Tue Mar 30 11:11:52 2010 UTC revision 518 by ph10, Tue May 18 15:47:01 2010 UTC
# Line 42  in the main Line 42  in the main
42  .\"  .\"
43  page.  page.
44  .P  .P
45    Another special sequence that may appear at the start of a pattern or in
46    combination with (*UTF8) is:
47    .sp
48      (*UCP)
49    .sp
50    This has the same effect as setting the PCRE_UCP option: it causes sequences
51    such as \ed and \ew to use Unicode properties to determine character types,
52    instead of recognizing only characters with codes less than 128 via a lookup
53    table.
54    .P
55  The remainder of this document discusses the patterns that are supported by  The remainder of this document discusses the patterns that are supported by
56  PCRE when its main matching function, \fBpcre_exec()\fP, is used.  PCRE when its main matching function, \fBpcre_exec()\fP, is used.
57  From release 6.0, PCRE offers a second matching function,  From release 6.0, PCRE offers a second matching function,
# Line 95  Perl-compatible, are recognized only at Line 105  Perl-compatible, are recognized only at
105  they must be in upper case. If more than one of them is present, the last one  they must be in upper case. If more than one of them is present, the last one
106  is used.  is used.
107  .P  .P
108  The newline convention does not affect what the \eR escape sequence matches. By  The newline convention affects the interpretation of the dot metacharacter when
109  default, this is any Unicode newline sequence, for Perl compatibility. However,  PCRE_DOTALL is not set, and also the behaviour of \eN. However, it does not
110  this can be changed; see the description of \eR in the section entitled  affect what the \eR escape sequence matches. By default, this is any Unicode
111    newline sequence, for Perl compatibility. However, this can be changed; see the
112    description of \eR in the section entitled
113  .\" HTML <a href="#newlineseq">  .\" HTML <a href="#newlineseq">
114  .\" </a>  .\" </a>
115  "Newline sequences"  "Newline sequences"
# Line 295  zero, because no more than three octal d Line 307  zero, because no more than three octal d
307  .P  .P
308  All the sequences that define a single character value can be used both inside  All the sequences that define a single character value can be used both inside
309  and outside character classes. In addition, inside a character class, the  and outside character classes. In addition, inside a character class, the
310  sequence \eb is interpreted as the backspace character (hex 08), and the  sequence \eb is interpreted as the backspace character (hex 08). The sequences
311  sequences \eR and \eX are interpreted as the characters "R" and "X",  \eB, \eN, \eR, and \eX are not special inside a character class. Like any other
312  respectively. Outside a character class, these sequences have different  unrecognized escape sequences, they are treated as the literal characters "B",
313  meanings  "N", "R", and "X" by default, but cause an error if the PCRE_EXTRA option is
314  .\" HTML <a href="#uniextseq">  set. Outside a character class, these sequences have different meanings.
 .\" </a>  
 (see below).  
 .\"  
315  .  .
316  .  .
317  .SS "Absolute and relative back references"  .SS "Absolute and relative back references"
# Line 341  subroutine Line 350  subroutine
350  call.  call.
351  .  .
352  .  .
353    .\" HTML <a name="genericchartypes"></a>
354  .SS "Generic character types"  .SS "Generic character types"
355  .rs  .rs
356  .sp  .sp
357  Another use of backslash is for specifying generic character types. The  Another use of backslash is for specifying generic character types:
 following are always recognized:  
358  .sp  .sp
359    \ed     any decimal digit    \ed     any decimal digit
360    \eD     any character that is not a decimal digit    \eD     any character that is not a decimal digit
# Line 358  following are always recognized: Line 367  following are always recognized:
367    \ew     any "word" character    \ew     any "word" character
368    \eW     any "non-word" character    \eW     any "non-word" character
369  .sp  .sp
370  Each pair of escape sequences partitions the complete set of characters into  There is also the single sequence \eN, which matches a non-newline character.
371  two disjoint sets. Any given character matches one, and only one, of each pair.  This is the same as
372    .\" HTML <a href="#fullstopdot">
373    .\" </a>
374    the "." metacharacter
375    .\"
376    when PCRE_DOTALL is not set.
377  .P  .P
378  These character type sequences can appear both inside and outside character  Each pair of lower and upper case escape sequences partitions the complete set
379    of characters into two disjoint sets. Any given character matches one, and only
380    one, of each pair. The sequences can appear both inside and outside character
381  classes. They each match one character of the appropriate type. If the current  classes. They each match one character of the appropriate type. If the current
382  matching point is at the end of the subject string, all of them fail, since  matching point is at the end of the subject string, all of them fail, because
383  there is no character to match.  there is no character to match.
384  .P  .P
385  For compatibility with Perl, \es does not match the VT character (code 11).  For compatibility with Perl, \es does not match the VT character (code 11).
# Line 372  are HT (9), LF (10), FF (12), CR (13), a Line 388  are HT (9), LF (10), FF (12), CR (13), a
388  included in a Perl script, \es may match the VT character. In PCRE, it never  included in a Perl script, \es may match the VT character. In PCRE, it never
389  does.  does.
390  .P  .P
391  In UTF-8 mode, characters with values greater than 128 never match \ed, \es, or  A "word" character is an underscore or any character that is a letter or digit.
392  \ew, and always match \eD, \eS, and \eW. This is true even when Unicode  By default, the definition of letters and digits is controlled by PCRE's
393  character property support is available. These sequences retain their original  low-valued character tables, and may vary if locale-specific matching is taking
394  meanings from before UTF-8 support was available, mainly for efficiency  place (see
395  reasons. Note that this also affects \eb, because it is defined in terms of \ew  .\" HTML <a href="pcreapi.html#localesupport">
396  and \eW.  .\" </a>
397    "Locale support"
398    .\"
399    in the
400    .\" HREF
401    \fBpcreapi\fP
402    .\"
403    page). For example, in a French locale such as "fr_FR" in Unix-like systems,
404    or "french" in Windows, some character codes greater than 128 are used for
405    accented letters, and these are then matched by \ew. The use of locales with
406    Unicode is discouraged.
407    .P
408    By default, in UTF-8 mode, characters with values greater than 128 never match
409    \ed, \es, or \ew, and always match \eD, \eS, and \eW. These sequences retain
410    their original meanings from before UTF-8 support was available, mainly for
411    efficiency reasons. However, if PCRE is compiled with Unicode property support,
412    and the PCRE_UCP option is set, the behaviour is changed so that Unicode
413    properties are used to determine character types, as follows:
414    .sp
415      \ed  any character that \ep{Nd} matches (decimal digit)
416      \es  any character that \ep{Z} matches, plus HT, LF, FF, CR
417      \ew  any character that \ep{L} or \ep{N} matches, plus underscore
418    .sp
419    The upper case escapes match the inverse sets of characters. Note that \ed
420    matches only decimal digits, whereas \ew matches any Unicode digit, as well as
421    any Unicode letter, and underscore. Note also that PCRE_UCP affects \eb, and
422    \eB because they are defined in terms of \ew and \eW. Matching these sequences
423    is noticeably slower when PCRE_UCP is set.
424  .P  .P
425  The sequences \eh, \eH, \ev, and \eV are Perl 5.10 features. In contrast to the  The sequences \eh, \eH, \ev, and \eV are Perl 5.10 features. In contrast to the
426  other sequences, these do match certain high-valued codepoints in UTF-8 mode.  other sequences, which match only ASCII characters by default, these always
427  The horizontal space characters are:  match certain high-valued codepoints in UTF-8 mode, whether or not PCRE_UCP is
428    set. The horizontal space characters are:
429  .sp  .sp
430    U+0009     Horizontal tab    U+0009     Horizontal tab
431    U+0020     Space    U+0020     Space
# Line 412  The vertical space characters are: Line 456  The vertical space characters are:
456    U+0085     Next line    U+0085     Next line
457    U+2028     Line separator    U+2028     Line separator
458    U+2029     Paragraph separator    U+2029     Paragraph separator
 .P  
 A "word" character is an underscore or any character less than 256 that is a  
 letter or digit. The definition of letters and digits is controlled by PCRE's  
 low-valued character tables, and may vary if locale-specific matching is taking  
 place (see  
 .\" HTML <a href="pcreapi.html#localesupport">  
 .\" </a>  
 "Locale support"  
 .\"  
 in the  
 .\" HREF  
 \fBpcreapi\fP  
 .\"  
 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 matched by \ew. The use of locales with Unicode  
 is discouraged.  
459  .  .
460  .  .
461  .\" HTML <a name="newlineseq"></a>  .\" HTML <a name="newlineseq"></a>
# Line 474  These override the default and the optio Line 501  These override the default and the optio
501  which are not Perl-compatible, are recognized only at the very start of a  which are not Perl-compatible, are recognized only at the very start of a
502  pattern, and that they must be in upper case. If more than one of them is  pattern, and that they must be in upper case. If more than one of them is
503  present, the last one is used. They can be combined with a change of newline  present, the last one is used. They can be combined with a change of newline
504  convention, for example, a pattern can start with:  convention; for example, a pattern can start with:
505  .sp  .sp
506    (*ANY)(*BSR_ANYCRLF)    (*ANY)(*BSR_ANYCRLF)
507  .sp  .sp
508  Inside a character class, \eR matches the letter "R".  They can also be combined with the (*UTF8) or (*UCP) special sequences. Inside
509    a character class, \eR is treated as an unrecognized escape sequence, and so
510    matches the letter "R" by default, but causes an error if PCRE_EXTRA is set.
511  .  .
512  .  .
513  .\" HTML <a name="uniextseq"></a>  .\" HTML <a name="uniextseq"></a>
# Line 496  The extra escape sequences are: Line 525  The extra escape sequences are:
525    \eX       an extended Unicode sequence    \eX       an extended Unicode sequence
526  .sp  .sp
527  The property names represented by \fIxx\fP above are limited to the Unicode  The property names represented by \fIxx\fP above are limited to the Unicode
528  script names, the general category properties, and "Any", which matches any  script names, the general category properties, "Any", which matches any
529  character (including newline). Other properties such as "InMusicalSymbols" are  character (including newline), and some special PCRE properties (described
530  not currently supported by PCRE. Note that \eP{Any} does not match any  in the
531  characters, so always causes a match failure.  .\" HTML <a href="#extraprops">
532    .\" </a>
533    next section).
534    .\"
535    Other Perl properties such as "InMusicalSymbols" are not currently supported by
536    PCRE. Note that \eP{Any} does not match any characters, so always causes a
537    match failure.
538  .P  .P
539  Sets of Unicode characters are defined as belonging to certain scripts. A  Sets of Unicode characters are defined as belonging to certain scripts. A
540  character from one of these sets can be matched using a script name. For  character from one of these sets can be matched using a script name. For
# Line 604  Ugaritic, Line 639  Ugaritic,
639  Vai,  Vai,
640  Yi.  Yi.
641  .P  .P
642  Each character has exactly one general category property, specified by a  Each character has exactly one Unicode general category property, specified by
643  two-letter abbreviation. For compatibility with Perl, negation can be specified  a two-letter abbreviation. For compatibility with Perl, negation can be
644  by including a circumflex between the opening brace and the property name. For  specified by including a circumflex between the opening brace and the property
645  example, \ep{^Lu} is the same as \eP{Lu}.  name. For example, \ep{^Lu} is the same as \eP{Lu}.
646  .P  .P
647  If only one letter is specified with \ep or \eP, it includes all the general  If only one letter is specified with \ep or \eP, it includes all the general
648  category properties that start with that letter. In this case, in the absence  category properties that start with that letter. In this case, in the absence
# Line 706  non-UTF-8 mode \eX matches any one chara Line 741  non-UTF-8 mode \eX matches any one chara
741  Matching characters by Unicode property is not fast, because PCRE has to search  Matching characters by Unicode property is not fast, because PCRE has to search
742  a structure that contains data for over fifteen thousand characters. That is  a structure that contains data for over fifteen thousand characters. That is
743  why the traditional escape sequences such as \ed and \ew do not use Unicode  why the traditional escape sequences such as \ed and \ew do not use Unicode
744  properties in PCRE.  properties in PCRE by default, though you can make them do so by setting the
745    PCRE_UCP option for \fBpcre_compile()\fP or by starting the pattern with
746    (*UCP).
747    .
748    .
749    .\" HTML <a name="extraprops"></a>
750    .SS PCRE's additional properties
751    .rs
752    .sp
753    As well as the standard Unicode properties described in the previous
754    section, PCRE supports four more that make it possible to convert traditional
755    escape sequences such as \ew and \es and POSIX character classes to use Unicode
756    properties. PCRE uses these non-standard, non-Perl properties internally when
757    PCRE_UCP is set. They are:
758    .sp
759      Xan   Any alphanumeric character
760      Xps   Any POSIX space character
761      Xsp   Any Perl space character
762      Xwd   Any Perl "word" character
763    .sp
764    Xan matches characters that have either the L (letter) or the N (number)
765    property. Xps matches the characters tab, linefeed, vertical tab, formfeed, or
766    carriage return, and any other character that has the Z (separator) property.
767    Xsp is the same as Xps, except that vertical tab is excluded. Xwd matches the
768    same characters as Xan, plus underscore.
769  .  .
770  .  .
771  .\" HTML <a name="resetmatchstart"></a>  .\" HTML <a name="resetmatchstart"></a>
# Line 765  The backslashed assertions are: Line 824  The backslashed assertions are:
824    \ez     matches only at the end of the subject    \ez     matches only at the end of the subject
825    \eG     matches at the first matching position in the subject    \eG     matches at the first matching position in the subject
826  .sp  .sp
827  These assertions may not appear in character classes (but note that \eb has a  Inside a character class, \eb has a different meaning; it matches the backspace
828  different meaning, namely the backspace character, inside a character class).  character. If any other of these assertions appears in a character class, by
829    default it matches the corresponding literal character (for example, \eB
830    matches the letter B). However, if the PCRE_EXTRA option is set, an "invalid
831    escape sequence" error is generated instead.
832  .P  .P
833  A word boundary is a position in the subject string where the current character  A word boundary is a position in the subject string where the current character
834  and the previous character do not both match \ew or \eW (i.e. one matches  and the previous character do not both match \ew or \eW (i.e. one matches
835  \ew and the other matches \eW), or the start or end of the string if the  \ew and the other matches \eW), or the start or end of the string if the
836  first or last character matches \ew, respectively. Neither PCRE nor Perl has a  first or last character matches \ew, respectively. In UTF-8 mode, the meanings
837  separte "start of word" or "end of word" metasequence. However, whatever  of \ew and \eW can be changed by setting the PCRE_UCP option. When this is
838  follows \eb normally determines which it is. For example, the fragment  done, it also affects \eb and \eB. Neither PCRE nor Perl has a separate "start
839  \eba matches "a" at the start of a word.  of word" or "end of word" metasequence. However, whatever follows \eb normally
840    determines which it is. For example, the fragment \eba matches "a" at the start
841    of a word.
842  .P  .P
843  The \eA, \eZ, and \ez assertions differ from the traditional circumflex and  The \eA, \eZ, and \ez assertions differ from the traditional circumflex and
844  dollar (described in the next section) in that they only ever match at the very  dollar (described in the next section) in that they only ever match at the very
# Line 858  end of the subject in both modes, and if Line 922  end of the subject in both modes, and if
922  \eA it is always anchored, whether or not PCRE_MULTILINE is set.  \eA it is always anchored, whether or not PCRE_MULTILINE is set.
923  .  .
924  .  .
925  .SH "FULL STOP (PERIOD, DOT)"  .\" HTML <a name="fullstopdot"></a>
926    .SH "FULL STOP (PERIOD, DOT) AND \eN"
927  .rs  .rs
928  .sp  .sp
929  Outside a character class, a dot in the pattern matches any one character in  Outside a character class, a dot in the pattern matches any one character in
# Line 880  to match it. Line 945  to match it.
945  The handling of dot is entirely independent of the handling of circumflex and  The handling of dot is entirely independent of the handling of circumflex and
946  dollar, the only relationship being that they both involve newlines. Dot has no  dollar, the only relationship being that they both involve newlines. Dot has no
947  special meaning in a character class.  special meaning in a character class.
948    .P
949    The escape sequence \eN always behaves as a dot does when PCRE_DOTALL is not
950    set. In other words, it matches any one character except one that signifies the
951    end of a line.
952  .  .
953  .  .
954  .SH "MATCHING A SINGLE BYTE"  .SH "MATCHING A SINGLE BYTE"
# Line 974  characters in both cases. In UTF-8 mode, Line 1043  characters in both cases. In UTF-8 mode,
1043  characters with values greater than 128 only when it is compiled with Unicode  characters with values greater than 128 only when it is compiled with Unicode
1044  property support.  property support.
1045  .P  .P
1046  The character types \ed, \eD, \ep, \eP, \es, \eS, \ew, and \eW may also appear  The character types \ed, \eD, \eh, \eH, \ep, \eP, \es, \eS, \ev, \eV, \ew, and
1047  in a character class, and add the characters that they match to the class. For  \eW may also appear in a character class, and add the characters that they
1048  example, [\edABCDEF] matches any hexadecimal digit. A circumflex can  match to the class. For example, [\edABCDEF] matches any hexadecimal digit. A
1049  conveniently be used with the upper case character types to specify a more  circumflex can conveniently be used with the upper case character types to
1050  restricted set of characters than the matching lower case type. For example,  specify a more restricted set of characters than the matching lower case type.
1051  the class [^\eW_] matches any letter or digit, but not underscore.  For example, the class [^\eW_] matches any letter or digit, but not underscore.
1052  .P  .P
1053  The only metacharacters that are recognized in character classes are backslash,  The only metacharacters that are recognized in character classes are backslash,
1054  hyphen (only where it can be interpreted as specifying a range), circumflex  hyphen (only where it can be interpreted as specifying a range), circumflex
# Line 999  this notation. For example, Line 1068  this notation. For example,
1068    [01[:alpha:]%]    [01[:alpha:]%]
1069  .sp  .sp
1070  matches "0", "1", any alphabetic character, or "%". The supported class names  matches "0", "1", any alphabetic character, or "%". The supported class names
1071  are  are:
1072  .sp  .sp
1073    alnum    letters and digits    alnum    letters and digits
1074    alpha    letters    alpha    letters
# Line 1010  are Line 1079  are
1079    graph    printing characters, excluding space    graph    printing characters, excluding space
1080    lower    lower case letters    lower    lower case letters
1081    print    printing characters, including space    print    printing characters, including space
1082    punct    printing characters, excluding letters and digits    punct    printing characters, excluding letters and digits and space
1083    space    white space (not quite the same as \es)    space    white space (not quite the same as \es)
1084    upper    upper case letters    upper    upper case letters
1085    word     "word" characters (same as \ew)    word     "word" characters (same as \ew)
# Line 1031  matches "1", "2", or any non-digit. PCRE Line 1100  matches "1", "2", or any non-digit. PCRE
1100  syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not  syntax [.ch.] and [=ch=] where "ch" is a "collating element", but these are not
1101  supported, and an error is given if they are encountered.  supported, and an error is given if they are encountered.
1102  .P  .P
1103  In UTF-8 mode, characters with values greater than 128 do not match any of  By default, in UTF-8 mode, characters with values greater than 128 do not match
1104  the POSIX character classes.  any of the POSIX character classes. However, if the PCRE_UCP option is passed
1105    to \fBpcre_compile()\fP, some of the classes are changed so that Unicode
1106    character properties are used. This is achieved by replacing the POSIX classes
1107    by other sequences, as follows:
1108    .sp
1109      [:alnum:]  becomes  \ep{Xan}
1110      [:alpha:]  becomes  \ep{L}
1111      [:blank:]  becomes  \eh
1112      [:digit:]  becomes  \ep{Nd}
1113      [:lower:]  becomes  \ep{Ll}
1114      [:space:]  becomes  \ep{Xps}
1115      [:upper:]  becomes  \ep{Lu}
1116      [:word:]   becomes  \ep{Xwd}
1117    .sp
1118    Negated versions, such as [:^alpha:] use \eP instead of \ep. The other POSIX
1119    classes are unchanged, and match only characters with code points less than
1120    128.
1121  .  .
1122  .  .
1123  .SH "VERTICAL BAR"  .SH "VERTICAL BAR"
# Line 1111  section entitled Line 1196  section entitled
1196  .\" </a>  .\" </a>
1197  "Newline sequences"  "Newline sequences"
1198  .\"  .\"
1199  above. There is also the (*UTF8) leading sequence that can be used to set UTF-8  above. There are also the (*UTF8) and (*UCP) leading sequences that can be used
1200  mode; this is equivalent to setting the PCRE_UTF8 option.  to set UTF-8 and Unicode property modes; they are equivalent to setting the
1201    PCRE_UTF8 and the PCRE_UCP options, respectively.
1202  .  .
1203  .  .
1204  .\" HTML <a name="subpattern"></a>  .\" HTML <a name="subpattern"></a>
# Line 2580  Cambridge CB2 3QH, England. Line 2666  Cambridge CB2 3QH, England.
2666  .rs  .rs
2667  .sp  .sp
2668  .nf  .nf
2669  Last updated: 27 March 2010  Last updated: 18 May 2010
2670  Copyright (c) 1997-2010 University of Cambridge.  Copyright (c) 1997-2010 University of Cambridge.
2671  .fi  .fi

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