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Contents of /code/trunk/doc/pcresyntax.3

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Update to Unicode 7.0.0 release
1 .TH PCRESYNTAX 3 "08 January 2014" "PCRE 8.35"
2 .SH NAME
3 PCRE - Perl-compatible regular expressions
4 .SH "PCRE REGULAR EXPRESSION SYNTAX SUMMARY"
5 .rs
6 .sp
7 The full syntax and semantics of the regular expressions that are supported by
8 PCRE are described in the
9 .\" HREF
10 \fBpcrepattern\fP
11 .\"
12 documentation. This document contains a quick-reference summary of the syntax.
13 .
14 .
15 .SH "QUOTING"
16 .rs
17 .sp
18 \ex where x is non-alphanumeric is a literal x
19 \eQ...\eE treat enclosed characters as literal
20 .
21 .
22 .SH "CHARACTERS"
23 .rs
24 .sp
25 \ea alarm, that is, the BEL character (hex 07)
26 \ecx "control-x", where x is any ASCII character
27 \ee escape (hex 1B)
28 \ef form feed (hex 0C)
29 \en newline (hex 0A)
30 \er carriage return (hex 0D)
31 \et tab (hex 09)
32 \e0dd character with octal code 0dd
33 \eddd character with octal code ddd, or backreference
34 \eo{ddd..} character with octal code ddd..
35 \exhh character with hex code hh
36 \ex{hhh..} character with hex code hhh..
37 .sp
38 Note that \e0dd is always an octal code, and that \e8 and \e9 are the literal
39 characters "8" and "9".
40 .
41 .
42 .SH "CHARACTER TYPES"
43 .rs
44 .sp
45 . any character except newline;
46 in dotall mode, any character whatsoever
47 \eC one data unit, even in UTF mode (best avoided)
48 \ed a decimal digit
49 \eD a character that is not a decimal digit
50 \eh a horizontal white space character
51 \eH a character that is not a horizontal white space character
52 \eN a character that is not a newline
53 \ep{\fIxx\fP} a character with the \fIxx\fP property
54 \eP{\fIxx\fP} a character without the \fIxx\fP property
55 \eR a newline sequence
56 \es a white space character
57 \eS a character that is not a white space character
58 \ev a vertical white space character
59 \eV a character that is not a vertical white space character
60 \ew a "word" character
61 \eW a "non-word" character
62 \eX a Unicode extended grapheme cluster
63 .sp
64 By default, \ed, \es, and \ew match only ASCII characters, even in UTF-8 mode
65 or in the 16- bit and 32-bit libraries. However, if locale-specific matching is
66 happening, \es and \ew may also match characters with code points in the range
67 128-255. If the PCRE_UCP option is set, the behaviour of these escape sequences
68 is changed to use Unicode properties and they match many more characters.
69 .
70 .
71 .SH "GENERAL CATEGORY PROPERTIES FOR \ep and \eP"
72 .rs
73 .sp
74 C Other
75 Cc Control
76 Cf Format
77 Cn Unassigned
78 Co Private use
79 Cs Surrogate
80 .sp
81 L Letter
82 Ll Lower case letter
83 Lm Modifier letter
84 Lo Other letter
85 Lt Title case letter
86 Lu Upper case letter
87 L& Ll, Lu, or Lt
88 .sp
89 M Mark
90 Mc Spacing mark
91 Me Enclosing mark
92 Mn Non-spacing mark
93 .sp
94 N Number
95 Nd Decimal number
96 Nl Letter number
97 No Other number
98 .sp
99 P Punctuation
100 Pc Connector punctuation
101 Pd Dash punctuation
102 Pe Close punctuation
103 Pf Final punctuation
104 Pi Initial punctuation
105 Po Other punctuation
106 Ps Open punctuation
107 .sp
108 S Symbol
109 Sc Currency symbol
110 Sk Modifier symbol
111 Sm Mathematical symbol
112 So Other symbol
113 .sp
114 Z Separator
115 Zl Line separator
116 Zp Paragraph separator
117 Zs Space separator
118 .
119 .
120 .SH "PCRE SPECIAL CATEGORY PROPERTIES FOR \ep and \eP"
121 .rs
122 .sp
123 Xan Alphanumeric: union of properties L and N
124 Xps POSIX space: property Z or tab, NL, VT, FF, CR
125 Xsp Perl space: property Z or tab, NL, VT, FF, CR
126 Xuc Univerally-named character: one that can be
127 represented by a Universal Character Name
128 Xwd Perl word: property Xan or underscore
129 .sp
130 Perl and POSIX space are now the same. Perl added VT to its space character set
131 at release 5.18 and PCRE changed at release 8.34.
132 .
133 .
134 .SH "SCRIPT NAMES FOR \ep AND \eP"
135 .rs
136 .sp
137 Arabic,
138 Armenian,
139 Avestan,
140 Balinese,
141 Bamum,
142 Bassa_Vah,
143 Batak,
144 Bengali,
145 Bopomofo,
146 Brahmi,
147 Braille,
148 Buginese,
149 Buhid,
150 Canadian_Aboriginal,
151 Carian,
152 Caucasian_Albanian,
153 Chakma,
154 Cham,
155 Cherokee,
156 Common,
157 Coptic,
158 Cuneiform,
159 Cypriot,
160 Cyrillic,
161 Deseret,
162 Devanagari,
163 Duployan,
164 Egyptian_Hieroglyphs,
165 Elbasan,
166 Ethiopic,
167 Georgian,
168 Glagolitic,
169 Gothic,
170 Grantha,
171 Greek,
172 Gujarati,
173 Gurmukhi,
174 Han,
175 Hangul,
176 Hanunoo,
177 Hebrew,
178 Hiragana,
179 Imperial_Aramaic,
180 Inherited,
181 Inscriptional_Pahlavi,
182 Inscriptional_Parthian,
183 Javanese,
184 Kaithi,
185 Kannada,
186 Katakana,
187 Kayah_Li,
188 Kharoshthi,
189 Khmer,
190 Khojki,
191 Khudawadi,
192 Lao,
193 Latin,
194 Lepcha,
195 Limbu,
196 Linear_A,
197 Linear_B,
198 Lisu,
199 Lycian,
200 Lydian,
201 Mahajani,
202 Malayalam,
203 Mandaic,
204 Manichaean,
205 Meetei_Mayek,
206 Mende_Kikakui,
207 Meroitic_Cursive,
208 Meroitic_Hieroglyphs,
209 Miao,
210 Modi,
211 Mongolian,
212 Mro,
213 Myanmar,
214 Nabataean,
215 New_Tai_Lue,
216 Nko,
217 Ogham,
218 Ol_Chiki,
219 Old_Italic,
220 Old_North_Arabian,
221 Old_Permic,
222 Old_Persian,
223 Old_South_Arabian,
224 Old_Turkic,
225 Oriya,
226 Osmanya,
227 Pahawh_Hmong,
228 Palmyrene,
229 Pau_Cin_Hau,
230 Phags_Pa,
231 Phoenician,
232 Psalter_Pahlavi,
233 Rejang,
234 Runic,
235 Samaritan,
236 Saurashtra,
237 Sharada,
238 Shavian,
239 Siddham,
240 Sinhala,
241 Sora_Sompeng,
242 Sundanese,
243 Syloti_Nagri,
244 Syriac,
245 Tagalog,
246 Tagbanwa,
247 Tai_Le,
248 Tai_Tham,
249 Tai_Viet,
250 Takri,
251 Tamil,
252 Telugu,
253 Thaana,
254 Thai,
255 Tibetan,
256 Tifinagh,
257 Tirhuta,
258 Ugaritic,
259 Vai,
260 Warang_Citi,
261 Yi.
262 .
263 .
264 .SH "CHARACTER CLASSES"
265 .rs
266 .sp
267 [...] positive character class
268 [^...] negative character class
269 [x-y] range (can be used for hex characters)
270 [[:xxx:]] positive POSIX named set
271 [[:^xxx:]] negative POSIX named set
272 .sp
273 alnum alphanumeric
274 alpha alphabetic
275 ascii 0-127
276 blank space or tab
277 cntrl control character
278 digit decimal digit
279 graph printing, excluding space
280 lower lower case letter
281 print printing, including space
282 punct printing, excluding alphanumeric
283 space white space
284 upper upper case letter
285 word same as \ew
286 xdigit hexadecimal digit
287 .sp
288 In PCRE, POSIX character set names recognize only ASCII characters by default,
289 but some of them use Unicode properties if PCRE_UCP is set. You can use
290 \eQ...\eE inside a character class.
291 .
292 .
293 .SH "QUANTIFIERS"
294 .rs
295 .sp
296 ? 0 or 1, greedy
297 ?+ 0 or 1, possessive
298 ?? 0 or 1, lazy
299 * 0 or more, greedy
300 *+ 0 or more, possessive
301 *? 0 or more, lazy
302 + 1 or more, greedy
303 ++ 1 or more, possessive
304 +? 1 or more, lazy
305 {n} exactly n
306 {n,m} at least n, no more than m, greedy
307 {n,m}+ at least n, no more than m, possessive
308 {n,m}? at least n, no more than m, lazy
309 {n,} n or more, greedy
310 {n,}+ n or more, possessive
311 {n,}? n or more, lazy
312 .
313 .
314 .SH "ANCHORS AND SIMPLE ASSERTIONS"
315 .rs
316 .sp
317 \eb word boundary
318 \eB not a word boundary
319 ^ start of subject
320 also after internal newline in multiline mode
321 \eA start of subject
322 $ end of subject
323 also before newline at end of subject
324 also before internal newline in multiline mode
325 \eZ end of subject
326 also before newline at end of subject
327 \ez end of subject
328 \eG first matching position in subject
329 .
330 .
331 .SH "MATCH POINT RESET"
332 .rs
333 .sp
334 \eK reset start of match
335 .sp
336 \eK is honoured in positive assertions, but ignored in negative ones.
337 .
338 .
339 .SH "ALTERNATION"
340 .rs
341 .sp
342 expr|expr|expr...
343 .
344 .
345 .SH "CAPTURING"
346 .rs
347 .sp
348 (...) capturing group
349 (?<name>...) named capturing group (Perl)
350 (?'name'...) named capturing group (Perl)
351 (?P<name>...) named capturing group (Python)
352 (?:...) non-capturing group
353 (?|...) non-capturing group; reset group numbers for
354 capturing groups in each alternative
355 .
356 .
357 .SH "ATOMIC GROUPS"
358 .rs
359 .sp
360 (?>...) atomic, non-capturing group
361 .
362 .
363 .
364 .
365 .SH "COMMENT"
366 .rs
367 .sp
368 (?#....) comment (not nestable)
369 .
370 .
371 .SH "OPTION SETTING"
372 .rs
373 .sp
374 (?i) caseless
375 (?J) allow duplicate names
376 (?m) multiline
377 (?s) single line (dotall)
378 (?U) default ungreedy (lazy)
379 (?x) extended (ignore white space)
380 (?-...) unset option(s)
381 .sp
382 The following are recognized only at the very start of a pattern or after one
383 of the newline or \eR options with similar syntax. More than one of them may
384 appear.
385 .sp
386 (*LIMIT_MATCH=d) set the match limit to d (decimal number)
387 (*LIMIT_RECURSION=d) set the recursion limit to d (decimal number)
388 (*NO_AUTO_POSSESS) no auto-possessification (PCRE_NO_AUTO_POSSESS)
389 (*NO_START_OPT) no start-match optimization (PCRE_NO_START_OPTIMIZE)
390 (*UTF8) set UTF-8 mode: 8-bit library (PCRE_UTF8)
391 (*UTF16) set UTF-16 mode: 16-bit library (PCRE_UTF16)
392 (*UTF32) set UTF-32 mode: 32-bit library (PCRE_UTF32)
393 (*UTF) set appropriate UTF mode for the library in use
394 (*UCP) set PCRE_UCP (use Unicode properties for \ed etc)
395 .sp
396 Note that LIMIT_MATCH and LIMIT_RECURSION can only reduce the value of the
397 limits set by the caller of pcre_exec(), not increase them.
398 .
399 .
400 .SH "NEWLINE CONVENTION"
401 .rs
402 .sp
403 These are recognized only at the very start of the pattern or after option
404 settings with a similar syntax.
405 .sp
406 (*CR) carriage return only
407 (*LF) linefeed only
408 (*CRLF) carriage return followed by linefeed
409 (*ANYCRLF) all three of the above
410 (*ANY) any Unicode newline sequence
411 .
412 .
413 .SH "WHAT \eR MATCHES"
414 .rs
415 .sp
416 These are recognized only at the very start of the pattern or after option
417 setting with a similar syntax.
418 .sp
419 (*BSR_ANYCRLF) CR, LF, or CRLF
420 (*BSR_UNICODE) any Unicode newline sequence
421 .
422 .
423 .SH "LOOKAHEAD AND LOOKBEHIND ASSERTIONS"
424 .rs
425 .sp
426 (?=...) positive look ahead
427 (?!...) negative look ahead
428 (?<=...) positive look behind
429 (?<!...) negative look behind
430 .sp
431 Each top-level branch of a look behind must be of a fixed length.
432 .
433 .
434 .SH "BACKREFERENCES"
435 .rs
436 .sp
437 \en reference by number (can be ambiguous)
438 \egn reference by number
439 \eg{n} reference by number
440 \eg{-n} relative reference by number
441 \ek<name> reference by name (Perl)
442 \ek'name' reference by name (Perl)
443 \eg{name} reference by name (Perl)
444 \ek{name} reference by name (.NET)
445 (?P=name) reference by name (Python)
446 .
447 .
448 .SH "SUBROUTINE REFERENCES (POSSIBLY RECURSIVE)"
449 .rs
450 .sp
451 (?R) recurse whole pattern
452 (?n) call subpattern by absolute number
453 (?+n) call subpattern by relative number
454 (?-n) call subpattern by relative number
455 (?&name) call subpattern by name (Perl)
456 (?P>name) call subpattern by name (Python)
457 \eg<name> call subpattern by name (Oniguruma)
458 \eg'name' call subpattern by name (Oniguruma)
459 \eg<n> call subpattern by absolute number (Oniguruma)
460 \eg'n' call subpattern by absolute number (Oniguruma)
461 \eg<+n> call subpattern by relative number (PCRE extension)
462 \eg'+n' call subpattern by relative number (PCRE extension)
463 \eg<-n> call subpattern by relative number (PCRE extension)
464 \eg'-n' call subpattern by relative number (PCRE extension)
465 .
466 .
467 .SH "CONDITIONAL PATTERNS"
468 .rs
469 .sp
470 (?(condition)yes-pattern)
471 (?(condition)yes-pattern|no-pattern)
472 .sp
473 (?(n)... absolute reference condition
474 (?(+n)... relative reference condition
475 (?(-n)... relative reference condition
476 (?(<name>)... named reference condition (Perl)
477 (?('name')... named reference condition (Perl)
478 (?(name)... named reference condition (PCRE)
479 (?(R)... overall recursion condition
480 (?(Rn)... specific group recursion condition
481 (?(R&name)... specific recursion condition
482 (?(DEFINE)... define subpattern for reference
483 (?(assert)... assertion condition
484 .
485 .
486 .SH "BACKTRACKING CONTROL"
487 .rs
488 .sp
489 The following act immediately they are reached:
490 .sp
491 (*ACCEPT) force successful match
492 (*FAIL) force backtrack; synonym (*F)
493 (*MARK:NAME) set name to be passed back; synonym (*:NAME)
494 .sp
495 The following act only when a subsequent match failure causes a backtrack to
496 reach them. They all force a match failure, but they differ in what happens
497 afterwards. Those that advance the start-of-match point do so only if the
498 pattern is not anchored.
499 .sp
500 (*COMMIT) overall failure, no advance of starting point
501 (*PRUNE) advance to next starting character
502 (*PRUNE:NAME) equivalent to (*MARK:NAME)(*PRUNE)
503 (*SKIP) advance to current matching position
504 (*SKIP:NAME) advance to position corresponding to an earlier
505 (*MARK:NAME); if not found, the (*SKIP) is ignored
506 (*THEN) local failure, backtrack to next alternation
507 (*THEN:NAME) equivalent to (*MARK:NAME)(*THEN)
508 .
509 .
510 .SH "CALLOUTS"
511 .rs
512 .sp
513 (?C) callout
514 (?Cn) callout with data n
515 .
516 .
517 .SH "SEE ALSO"
518 .rs
519 .sp
520 \fBpcrepattern\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3),
521 \fBpcrematching\fP(3), \fBpcre\fP(3).
522 .
523 .
524 .SH AUTHOR
525 .rs
526 .sp
527 .nf
528 Philip Hazel
529 University Computing Service
530 Cambridge CB2 3QH, England.
531 .fi
532 .
533 .
534 .SH REVISION
535 .rs
536 .sp
537 .nf
538 Last updated: 08 January 2014
539 Copyright (c) 1997-2014 University of Cambridge.
540 .fi

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