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1 PCRETEST(1) PCRETEST(1)
2
3
4 NAME
5 pcretest - a program for testing Perl-compatible regular expressions.
6
7
8 SYNOPSIS
9
10 pcretest [options] [source] [destination]
11
12 pcretest was written as a test program for the PCRE regular expression
13 library itself, but it can also be used for experimenting with regular
14 expressions. This document describes the features of the test program;
15 for details of the regular expressions themselves, see the pcrepattern
16 documentation. For details of the PCRE library function calls and their
17 options, see the pcreapi documentation.
18
19
20 OPTIONS
21
22 -b Behave as if each regex has the /B (show bytecode) modifier;
23 the internal form is output after compilation.
24
25 -C Output the version number of the PCRE library, and all avail-
26 able information about the optional features that are
27 included, and then exit.
28
29 -d Behave as if each regex has the /D (debug) modifier; the
30 internal form and information about the compiled pattern is
31 output after compilation; -d is equivalent to -b -i.
32
33 -dfa Behave as if each data line contains the \D escape sequence;
34 this causes the alternative matching function,
35 pcre_dfa_exec(), to be used instead of the standard
36 pcre_exec() function (more detail is given below).
37
38 -help Output a brief summary these options and then exit.
39
40 -i Behave as if each regex has the /I modifier; information
41 about the compiled pattern is given after compilation.
42
43 -m Output the size of each compiled pattern after it has been
44 compiled. This is equivalent to adding /M to each regular
45 expression. For compatibility with earlier versions of
46 pcretest, -s is a synonym for -m.
47
48 -o osize Set the number of elements in the output vector that is used
49 when calling pcre_exec() or pcre_dfa_exec() to be osize. The
50 default value is 45, which is enough for 14 capturing subex-
51 pressions for pcre_exec() or 22 different matches for
52 pcre_dfa_exec(). The vector size can be changed for individ-
53 ual matching calls by including \O in the data line (see
54 below).
55
56 -p Behave as if each regex has the /P modifier; the POSIX wrap-
57 per API is used to call PCRE. None of the other options has
58 any effect when -p is set.
59
60 -q Do not output the version number of pcretest at the start of
61 execution.
62
63 -S size On Unix-like systems, set the size of the runtime stack to
64 size megabytes.
65
66 -t Run each compile, study, and match many times with a timer,
67 and output resulting time per compile or match (in millisec-
68 onds). Do not set -m with -t, because you will then get the
69 size output a zillion times, and the timing will be dis-
70 torted. You can control the number of iterations that are
71 used for timing by following -t with a number (as a separate
72 item on the command line). For example, "-t 1000" would iter-
73 ate 1000 times. The default is to iterate 500000 times.
74
75 -tm This is like -t except that it times only the matching phase,
76 not the compile or study phases.
77
78
79 DESCRIPTION
80
81 If pcretest is given two filename arguments, it reads from the first
82 and writes to the second. If it is given only one filename argument, it
83 reads from that file and writes to stdout. Otherwise, it reads from
84 stdin and writes to stdout, and prompts for each line of input, using
85 "re>" to prompt for regular expressions, and "data>" to prompt for data
86 lines.
87
88 The program handles any number of sets of input on a single input file.
89 Each set starts with a regular expression, and continues with any num-
90 ber of data lines to be matched against the pattern.
91
92 Each data line is matched separately and independently. If you want to
93 do multi-line matches, you have to use the \n escape sequence (or \r or
94 \r\n, etc., depending on the newline setting) in a single line of input
95 to encode the newline sequences. There is no limit on the length of
96 data lines; the input buffer is automatically extended if it is too
97 small.
98
99 An empty line signals the end of the data lines, at which point a new
100 regular expression is read. The regular expressions are given enclosed
101 in any non-alphanumeric delimiters other than backslash, for example:
102
103 /(a|bc)x+yz/
104
105 White space before the initial delimiter is ignored. A regular expres-
106 sion may be continued over several input lines, in which case the new-
107 line characters are included within it. It is possible to include the
108 delimiter within the pattern by escaping it, for example
109
110 /abc\/def/
111
112 If you do so, the escape and the delimiter form part of the pattern,
113 but since delimiters are always non-alphanumeric, this does not affect
114 its interpretation. If the terminating delimiter is immediately fol-
115 lowed by a backslash, for example,
116
117 /abc/\
118
119 then a backslash is added to the end of the pattern. This is done to
120 provide a way of testing the error condition that arises if a pattern
121 finishes with a backslash, because
122
123 /abc\/
124
125 is interpreted as the first line of a pattern that starts with "abc/",
126 causing pcretest to read the next line as a continuation of the regular
127 expression.
128
129
130 PATTERN MODIFIERS
131
132 A pattern may be followed by any number of modifiers, which are mostly
133 single characters. Following Perl usage, these are referred to below
134 as, for example, "the /i modifier", even though the delimiter of the
135 pattern need not always be a slash, and no slash is used when writing
136 modifiers. Whitespace may appear between the final pattern delimiter
137 and the first modifier, and between the modifiers themselves.
138
139 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
140 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
141 pile() is called. These four modifier letters have the same effect as
142 they do in Perl. For example:
143
144 /caseless/i
145
146 The following table shows additional modifiers for setting PCRE options
147 that do not correspond to anything in Perl:
148
149 /A PCRE_ANCHORED
150 /C PCRE_AUTO_CALLOUT
151 /E PCRE_DOLLAR_ENDONLY
152 /f PCRE_FIRSTLINE
153 /J PCRE_DUPNAMES
154 /N PCRE_NO_AUTO_CAPTURE
155 /U PCRE_UNGREEDY
156 /X PCRE_EXTRA
157 /<cr> PCRE_NEWLINE_CR
158 /<lf> PCRE_NEWLINE_LF
159 /<crlf> PCRE_NEWLINE_CRLF
160 /<anycrlf> PCRE_NEWLINE_ANY
161 /<any> PCRE_NEWLINE_ANY
162
163 Those specifying line ending sequencess are literal strings as shown.
164 This example sets multiline matching with CRLF as the line ending
165 sequence:
166
167 /^abc/m<crlf>
168
169 Details of the meanings of these PCRE options are given in the pcreapi
170 documentation.
171
172 Finding all matches in a string
173
174 Searching for all possible matches within each subject string can be
175 requested by the /g or /G modifier. After finding a match, PCRE is
176 called again to search the remainder of the subject string. The differ-
177 ence between /g and /G is that the former uses the startoffset argument
178 to pcre_exec() to start searching at a new point within the entire
179 string (which is in effect what Perl does), whereas the latter passes
180 over a shortened substring. This makes a difference to the matching
181 process if the pattern begins with a lookbehind assertion (including \b
182 or \B).
183
184 If any call to pcre_exec() in a /g or /G sequence matches an empty
185 string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
186 flags set in order to search for another, non-empty, match at the same
187 point. If this second match fails, the start offset is advanced by
188 one, and the normal match is retried. This imitates the way Perl han-
189 dles such cases when using the /g modifier or the split() function.
190
191 Other modifiers
192
193 There are yet more modifiers for controlling the way pcretest operates.
194
195 The /+ modifier requests that as well as outputting the substring that
196 matched the entire pattern, pcretest should in addition output the
197 remainder of the subject string. This is useful for tests where the
198 subject contains multiple copies of the same substring.
199
200 The /B modifier is a debugging feature. It requests that pcretest out-
201 put a representation of the compiled byte code after compilation. Nor-
202 mally this information contains length and offset values; however, if
203 /Z is also present, this data is replaced by spaces. This is a special
204 feature for use in the automatic test scripts; it ensures that the same
205 output is generated for different internal link sizes.
206
207 The /L modifier must be followed directly by the name of a locale, for
208 example,
209
210 /pattern/Lfr_FR
211
212 For this reason, it must be the last modifier. The given locale is set,
213 pcre_maketables() is called to build a set of character tables for the
214 locale, and this is then passed to pcre_compile() when compiling the
215 regular expression. Without an /L modifier, NULL is passed as the
216 tables pointer; that is, /L applies only to the expression on which it
217 appears.
218
219 The /I modifier requests that pcretest output information about the
220 compiled pattern (whether it is anchored, has a fixed first character,
221 and so on). It does this by calling pcre_fullinfo() after compiling a
222 pattern. If the pattern is studied, the results of that are also out-
223 put.
224
225 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
226 that is, both the /B and the /I modifiers.
227
228 The /F modifier causes pcretest to flip the byte order of the fields in
229 the compiled pattern that contain 2-byte and 4-byte numbers. This
230 facility is for testing the feature in PCRE that allows it to execute
231 patterns that were compiled on a host with a different endianness. This
232 feature is not available when the POSIX interface to PCRE is being
233 used, that is, when the /P pattern modifier is specified. See also the
234 section about saving and reloading compiled patterns below.
235
236 The /S modifier causes pcre_study() to be called after the expression
237 has been compiled, and the results used when the expression is matched.
238
239 The /M modifier causes the size of memory block used to hold the com-
240 piled pattern to be output.
241
242 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
243 rather than its native API. When this is done, all other modifiers
244 except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
245 and REG_NEWLINE is set if /m is present. The wrapper functions force
246 PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
247
248 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
249 set. This turns on support for UTF-8 character handling in PCRE, pro-
250 vided that it was compiled with this support enabled. This modifier
251 also causes any non-printing characters in output strings to be printed
252 using the \x{hh...} notation if they are valid UTF-8 sequences.
253
254 If the /? modifier is used with /8, it causes pcretest to call
255 pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
256 checking of the string for UTF-8 validity.
257
258
259 DATA LINES
260
261 Before each data line is passed to pcre_exec(), leading and trailing
262 whitespace is removed, and it is then scanned for \ escapes. Some of
263 these are pretty esoteric features, intended for checking out some of
264 the more complicated features of PCRE. If you are just testing "ordi-
265 nary" regular expressions, you probably don't need any of these. The
266 following escapes are recognized:
267
268 \a alarm (BEL, \x07)
269 \b backspace (\x08)
270 \e escape (\x27)
271 \f formfeed (\x0c)
272 \n newline (\x0a)
273 \qdd set the PCRE_MATCH_LIMIT limit to dd
274 (any number of digits)
275 \r carriage return (\x0d)
276 \t tab (\x09)
277 \v vertical tab (\x0b)
278 \nnn octal character (up to 3 octal digits)
279 \xhh hexadecimal character (up to 2 hex digits)
280 \x{hh...} hexadecimal character, any number of digits
281 in UTF-8 mode
282 \A pass the PCRE_ANCHORED option to pcre_exec()
283 or pcre_dfa_exec()
284 \B pass the PCRE_NOTBOL option to pcre_exec()
285 or pcre_dfa_exec()
286 \Cdd call pcre_copy_substring() for substring dd
287 after a successful match (number less than 32)
288 \Cname call pcre_copy_named_substring() for substring
289 "name" after a successful match (name termin-
290 ated by next non alphanumeric character)
291 \C+ show the current captured substrings at callout
292 time
293 \C- do not supply a callout function
294 \C!n return 1 instead of 0 when callout number n is
295 reached
296 \C!n!m return 1 instead of 0 when callout number n is
297 reached for the nth time
298 \C*n pass the number n (may be negative) as callout
299 data; this is used as the callout return value
300 \D use the pcre_dfa_exec() match function
301 \F only shortest match for pcre_dfa_exec()
302 \Gdd call pcre_get_substring() for substring dd
303 after a successful match (number less than 32)
304 \Gname call pcre_get_named_substring() for substring
305 "name" after a successful match (name termin-
306 ated by next non-alphanumeric character)
307 \L call pcre_get_substringlist() after a
308 successful match
309 \M discover the minimum MATCH_LIMIT and
310 MATCH_LIMIT_RECURSION settings
311 \N pass the PCRE_NOTEMPTY option to pcre_exec()
312 or pcre_dfa_exec()
313 \Odd set the size of the output vector passed to
314 pcre_exec() to dd (any number of digits)
315 \P pass the PCRE_PARTIAL option to pcre_exec()
316 or pcre_dfa_exec()
317 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
318 (any number of digits)
319 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
320 \S output details of memory get/free calls during matching
321 \Z pass the PCRE_NOTEOL option to pcre_exec()
322 or pcre_dfa_exec()
323 \? pass the PCRE_NO_UTF8_CHECK option to
324 pcre_exec() or pcre_dfa_exec()
325 \>dd start the match at offset dd (any number of digits);
326 this sets the startoffset argument for pcre_exec()
327 or pcre_dfa_exec()
328 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
329 or pcre_dfa_exec()
330 \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
331 or pcre_dfa_exec()
332 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
333 or pcre_dfa_exec()
334 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
335 or pcre_dfa_exec()
336 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
337 or pcre_dfa_exec()
338
339 The escapes that specify line ending sequences are literal strings,
340 exactly as shown. No more than one newline setting should be present in
341 any data line.
342
343 A backslash followed by anything else just escapes the anything else.
344 If the very last character is a backslash, it is ignored. This gives a
345 way of passing an empty line as data, since a real empty line termi-
346 nates the data input.
347
348 If \M is present, pcretest calls pcre_exec() several times, with dif-
349 ferent values in the match_limit and match_limit_recursion fields of
350 the pcre_extra data structure, until it finds the minimum numbers for
351 each parameter that allow pcre_exec() to complete. The match_limit num-
352 ber is a measure of the amount of backtracking that takes place, and
353 checking it out can be instructive. For most simple matches, the number
354 is quite small, but for patterns with very large numbers of matching
355 possibilities, it can become large very quickly with increasing length
356 of subject string. The match_limit_recursion number is a measure of how
357 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
358 memory is needed to complete the match attempt.
359
360 When \O is used, the value specified may be higher or lower than the
361 size set by the -O command line option (or defaulted to 45); \O applies
362 only to the call of pcre_exec() for the line in which it appears.
363
364 If the /P modifier was present on the pattern, causing the POSIX wrap-
365 per API to be used, the only option-setting sequences that have any
366 effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
367 to be passed to regexec().
368
369 The use of \x{hh...} to represent UTF-8 characters is not dependent on
370 the use of the /8 modifier on the pattern. It is recognized always.
371 There may be any number of hexadecimal digits inside the braces. The
372 result is from one to six bytes, encoded according to the UTF-8 rules.
373
374
375 THE ALTERNATIVE MATCHING FUNCTION
376
377 By default, pcretest uses the standard PCRE matching function,
378 pcre_exec() to match each data line. From release 6.0, PCRE supports an
379 alternative matching function, pcre_dfa_test(), which operates in a
380 different way, and has some restrictions. The differences between the
381 two functions are described in the pcrematching documentation.
382
383 If a data line contains the \D escape sequence, or if the command line
384 contains the -dfa option, the alternative matching function is called.
385 This function finds all possible matches at a given point. If, however,
386 the \F escape sequence is present in the data line, it stops after the
387 first match is found. This is always the shortest possible match.
388
389
390 DEFAULT OUTPUT FROM PCRETEST
391
392 This section describes the output when the normal matching function,
393 pcre_exec(), is being used.
394
395 When a match succeeds, pcretest outputs the list of captured substrings
396 that pcre_exec() returns, starting with number 0 for the string that
397 matched the whole pattern. Otherwise, it outputs "No match" or "Partial
398 match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
399 TIAL, respectively, and otherwise the PCRE negative error number. Here
400 is an example of an interactive pcretest run.
401
402 $ pcretest
403 PCRE version 7.0 30-Nov-2006
404
405 re> /^abc(\d+)/
406 data> abc123
407 0: abc123
408 1: 123
409 data> xyz
410 No match
411
412 If the strings contain any non-printing characters, they are output as
413 \0x escapes, or as \x{...} escapes if the /8 modifier was present on
414 the pattern. See below for the definition of non-printing characters.
415 If the pattern has the /+ modifier, the output for substring 0 is fol-
416 lowed by the the rest of the subject string, identified by "0+" like
417 this:
418
419 re> /cat/+
420 data> cataract
421 0: cat
422 0+ aract
423
424 If the pattern has the /g or /G modifier, the results of successive
425 matching attempts are output in sequence, like this:
426
427 re> /\Bi(\w\w)/g
428 data> Mississippi
429 0: iss
430 1: ss
431 0: iss
432 1: ss
433 0: ipp
434 1: pp
435
436 "No match" is output only if the first match attempt fails.
437
438 If any of the sequences \C, \G, or \L are present in a data line that
439 is successfully matched, the substrings extracted by the convenience
440 functions are output with C, G, or L after the string number instead of
441 a colon. This is in addition to the normal full list. The string length
442 (that is, the return from the extraction function) is given in paren-
443 theses after each string for \C and \G.
444
445 Note that whereas patterns can be continued over several lines (a plain
446 ">" prompt is used for continuations), data lines may not. However new-
447 lines can be included in data by means of the \n escape (or \r, \r\n,
448 etc., depending on the newline sequence setting).
449
450
451 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
452
453 When the alternative matching function, pcre_dfa_exec(), is used (by
454 means of the \D escape sequence or the -dfa command line option), the
455 output consists of a list of all the matches that start at the first
456 point in the subject where there is at least one match. For example:
457
458 re> /(tang|tangerine|tan)/
459 data> yellow tangerine\D
460 0: tangerine
461 1: tang
462 2: tan
463
464 (Using the normal matching function on this data finds only "tang".)
465 The longest matching string is always given first (and numbered zero).
466
467 If /g is present on the pattern, the search for further matches resumes
468 at the end of the longest match. For example:
469
470 re> /(tang|tangerine|tan)/g
471 data> yellow tangerine and tangy sultana\D
472 0: tangerine
473 1: tang
474 2: tan
475 0: tang
476 1: tan
477 0: tan
478
479 Since the matching function does not support substring capture, the
480 escape sequences that are concerned with captured substrings are not
481 relevant.
482
483
484 RESTARTING AFTER A PARTIAL MATCH
485
486 When the alternative matching function has given the PCRE_ERROR_PARTIAL
487 return, indicating that the subject partially matched the pattern, you
488 can restart the match with additional subject data by means of the \R
489 escape sequence. For example:
490
491 re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/
492 data> 23ja\P\D
493 Partial match: 23ja
494 data> n05\R\D
495 0: n05
496
497 For further information about partial matching, see the pcrepartial
498 documentation.
499
500
501 CALLOUTS
502
503 If the pattern contains any callout requests, pcretest's callout func-
504 tion is called during matching. This works with both matching func-
505 tions. By default, the called function displays the callout number, the
506 start and current positions in the text at the callout time, and the
507 next pattern item to be tested. For example, the output
508
509 --->pqrabcdef
510 0 ^ ^ \d
511
512 indicates that callout number 0 occurred for a match attempt starting
513 at the fourth character of the subject string, when the pointer was at
514 the seventh character of the data, and when the next pattern item was
515 \d. Just one circumflex is output if the start and current positions
516 are the same.
517
518 Callouts numbered 255 are assumed to be automatic callouts, inserted as
519 a result of the /C pattern modifier. In this case, instead of showing
520 the callout number, the offset in the pattern, preceded by a plus, is
521 output. For example:
522
523 re> /\d?[A-E]\*/C
524 data> E*
525 --->E*
526 +0 ^ \d?
527 +3 ^ [A-E]
528 +8 ^^ \*
529 +10 ^ ^
530 0: E*
531
532 The callout function in pcretest returns zero (carry on matching) by
533 default, but you can use a \C item in a data line (as described above)
534 to change this.
535
536 Inserting callouts can be helpful when using pcretest to check compli-
537 cated regular expressions. For further information about callouts, see
538 the pcrecallout documentation.
539
540
541 NON-PRINTING CHARACTERS
542
543 When pcretest is outputting text in the compiled version of a pattern,
544 bytes other than 32-126 are always treated as non-printing characters
545 are are therefore shown as hex escapes.
546
547 When pcretest is outputting text that is a matched part of a subject
548 string, it behaves in the same way, unless a different locale has been
549 set for the pattern (using the /L modifier). In this case, the
550 isprint() function to distinguish printing and non-printing characters.
551
552
553 SAVING AND RELOADING COMPILED PATTERNS
554
555 The facilities described in this section are not available when the
556 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
557 ifier is specified.
558
559 When the POSIX interface is not in use, you can cause pcretest to write
560 a compiled pattern to a file, by following the modifiers with > and a
561 file name. For example:
562
563 /pattern/im >/some/file
564
565 See the pcreprecompile documentation for a discussion about saving and
566 re-using compiled patterns.
567
568 The data that is written is binary. The first eight bytes are the
569 length of the compiled pattern data followed by the length of the
570 optional study data, each written as four bytes in big-endian order
571 (most significant byte first). If there is no study data (either the
572 pattern was not studied, or studying did not return any data), the sec-
573 ond length is zero. The lengths are followed by an exact copy of the
574 compiled pattern. If there is additional study data, this follows imme-
575 diately after the compiled pattern. After writing the file, pcretest
576 expects to read a new pattern.
577
578 A saved pattern can be reloaded into pcretest by specifing < and a file
579 name instead of a pattern. The name of the file must not contain a <
580 character, as otherwise pcretest will interpret the line as a pattern
581 delimited by < characters. For example:
582
583 re> </some/file
584 Compiled regex loaded from /some/file
585 No study data
586
587 When the pattern has been loaded, pcretest proceeds to read data lines
588 in the usual way.
589
590 You can copy a file written by pcretest to a different host and reload
591 it there, even if the new host has opposite endianness to the one on
592 which the pattern was compiled. For example, you can compile on an i86
593 machine and run on a SPARC machine.
594
595 File names for saving and reloading can be absolute or relative, but
596 note that the shell facility of expanding a file name that starts with
597 a tilde (~) is not available.
598
599 The ability to save and reload files in pcretest is intended for test-
600 ing and experimentation. It is not intended for production use because
601 only a single pattern can be written to a file. Furthermore, there is
602 no facility for supplying custom character tables for use with a
603 reloaded pattern. If the original pattern was compiled with custom
604 tables, an attempt to match a subject string using a reloaded pattern
605 is likely to cause pcretest to crash. Finally, if you attempt to load
606 a file that is not in the correct format, the result is undefined.
607
608
609 SEE ALSO
610
611 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
612 pcrepattern(3), pcreprecompile(3).
613
614
615 AUTHOR
616
617 Philip Hazel
618 University Computing Service
619 Cambridge CB2 3QH, England.
620
621
622 REVISION
623
624 Last updated: 16 April 2007
625 Copyright (c) 1997-2007 University of Cambridge.

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