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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 /<any> PCRE_NEWLINE_ANY
161
162 Those specifying line ending sequencess are literal strings as shown.
163 This example sets multiline matching with CRLF as the line ending
164 sequence:
165
166 /^abc/m<crlf>
167
168 Details of the meanings of these PCRE options are given in the pcreapi
169 documentation.
170
171 Finding all matches in a string
172
173 Searching for all possible matches within each subject string can be
174 requested by the /g or /G modifier. After finding a match, PCRE is
175 called again to search the remainder of the subject string. The differ-
176 ence between /g and /G is that the former uses the startoffset argument
177 to pcre_exec() to start searching at a new point within the entire
178 string (which is in effect what Perl does), whereas the latter passes
179 over a shortened substring. This makes a difference to the matching
180 process if the pattern begins with a lookbehind assertion (including \b
181 or \B).
182
183 If any call to pcre_exec() in a /g or /G sequence matches an empty
184 string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
185 flags set in order to search for another, non-empty, match at the same
186 point. If this second match fails, the start offset is advanced by
187 one, and the normal match is retried. This imitates the way Perl han-
188 dles such cases when using the /g modifier or the split() function.
189
190 Other modifiers
191
192 There are yet more modifiers for controlling the way pcretest operates.
193
194 The /+ modifier requests that as well as outputting the substring that
195 matched the entire pattern, pcretest should in addition output the
196 remainder of the subject string. This is useful for tests where the
197 subject contains multiple copies of the same substring.
198
199 The /B modifier is a debugging feature. It requests that pcretest out-
200 put a representation of the compiled byte code after compilation. Nor-
201 mally this information contains length and offset values; however, if
202 /Z is also present, this data is replaced by spaces. This is a special
203 feature for use in the automatic test scripts; it ensures that the same
204 output is generated for different internal link sizes.
205
206 The /L modifier must be followed directly by the name of a locale, for
207 example,
208
209 /pattern/Lfr_FR
210
211 For this reason, it must be the last modifier. The given locale is set,
212 pcre_maketables() is called to build a set of character tables for the
213 locale, and this is then passed to pcre_compile() when compiling the
214 regular expression. Without an /L modifier, NULL is passed as the
215 tables pointer; that is, /L applies only to the expression on which it
216 appears.
217
218 The /I modifier requests that pcretest output information about the
219 compiled pattern (whether it is anchored, has a fixed first character,
220 and so on). It does this by calling pcre_fullinfo() after compiling a
221 pattern. If the pattern is studied, the results of that are also out-
222 put.
223
224 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
225 that is, both the /B and the /I modifiers.
226
227 The /F modifier causes pcretest to flip the byte order of the fields in
228 the compiled pattern that contain 2-byte and 4-byte numbers. This
229 facility is for testing the feature in PCRE that allows it to execute
230 patterns that were compiled on a host with a different endianness. This
231 feature is not available when the POSIX interface to PCRE is being
232 used, that is, when the /P pattern modifier is specified. See also the
233 section about saving and reloading compiled patterns below.
234
235 The /S modifier causes pcre_study() to be called after the expression
236 has been compiled, and the results used when the expression is matched.
237
238 The /M modifier causes the size of memory block used to hold the com-
239 piled pattern to be output.
240
241 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
242 rather than its native API. When this is done, all other modifiers
243 except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
244 and REG_NEWLINE is set if /m is present. The wrapper functions force
245 PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
246
247 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
248 set. This turns on support for UTF-8 character handling in PCRE, pro-
249 vided that it was compiled with this support enabled. This modifier
250 also causes any non-printing characters in output strings to be printed
251 using the \x{hh...} notation if they are valid UTF-8 sequences.
252
253 If the /? modifier is used with /8, it causes pcretest to call
254 pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
255 checking of the string for UTF-8 validity.
256
257
258 DATA LINES
259
260 Before each data line is passed to pcre_exec(), leading and trailing
261 whitespace is removed, and it is then scanned for \ escapes. Some of
262 these are pretty esoteric features, intended for checking out some of
263 the more complicated features of PCRE. If you are just testing "ordi-
264 nary" regular expressions, you probably don't need any of these. The
265 following escapes are recognized:
266
267 \a alarm (BEL, \x07)
268 \b backspace (\x08)
269 \e escape (\x27)
270 \f formfeed (\x0c)
271 \n newline (\x0a)
272 \qdd set the PCRE_MATCH_LIMIT limit to dd
273 (any number of digits)
274 \r carriage return (\x0d)
275 \t tab (\x09)
276 \v vertical tab (\x0b)
277 \nnn octal character (up to 3 octal digits)
278 \xhh hexadecimal character (up to 2 hex digits)
279 \x{hh...} hexadecimal character, any number of digits
280 in UTF-8 mode
281 \A pass the PCRE_ANCHORED option to pcre_exec()
282 or pcre_dfa_exec()
283 \B pass the PCRE_NOTBOL option to pcre_exec()
284 or pcre_dfa_exec()
285 \Cdd call pcre_copy_substring() for substring dd
286 after a successful match (number less than 32)
287 \Cname call pcre_copy_named_substring() for substring
288 "name" after a successful match (name termin-
289 ated by next non alphanumeric character)
290 \C+ show the current captured substrings at callout
291 time
292 \C- do not supply a callout function
293 \C!n return 1 instead of 0 when callout number n is
294 reached
295 \C!n!m return 1 instead of 0 when callout number n is
296 reached for the nth time
297 \C*n pass the number n (may be negative) as callout
298 data; this is used as the callout return value
299 \D use the pcre_dfa_exec() match function
300 \F only shortest match for pcre_dfa_exec()
301 \Gdd call pcre_get_substring() for substring dd
302 after a successful match (number less than 32)
303 \Gname call pcre_get_named_substring() for substring
304 "name" after a successful match (name termin-
305 ated by next non-alphanumeric character)
306 \L call pcre_get_substringlist() after a
307 successful match
308 \M discover the minimum MATCH_LIMIT and
309 MATCH_LIMIT_RECURSION settings
310 \N pass the PCRE_NOTEMPTY option to pcre_exec()
311 or pcre_dfa_exec()
312 \Odd set the size of the output vector passed to
313 pcre_exec() to dd (any number of digits)
314 \P pass the PCRE_PARTIAL option to pcre_exec()
315 or pcre_dfa_exec()
316 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
317 (any number of digits)
318 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
319 \S output details of memory get/free calls during matching
320 \Z pass the PCRE_NOTEOL option to pcre_exec()
321 or pcre_dfa_exec()
322 \? pass the PCRE_NO_UTF8_CHECK option to
323 pcre_exec() or pcre_dfa_exec()
324 \>dd start the match at offset dd (any number of digits);
325 this sets the startoffset argument for pcre_exec()
326 or pcre_dfa_exec()
327 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
328 or pcre_dfa_exec()
329 \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
330 or pcre_dfa_exec()
331 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
332 or pcre_dfa_exec()
333 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
334 or pcre_dfa_exec()
335
336 The escapes that specify line ending sequences are literal strings,
337 exactly as shown. No more than one newline setting should be present in
338 any data line.
339
340 A backslash followed by anything else just escapes the anything else.
341 If the very last character is a backslash, it is ignored. This gives a
342 way of passing an empty line as data, since a real empty line termi-
343 nates the data input.
344
345 If \M is present, pcretest calls pcre_exec() several times, with dif-
346 ferent values in the match_limit and match_limit_recursion fields of
347 the pcre_extra data structure, until it finds the minimum numbers for
348 each parameter that allow pcre_exec() to complete. The match_limit num-
349 ber is a measure of the amount of backtracking that takes place, and
350 checking it out can be instructive. For most simple matches, the number
351 is quite small, but for patterns with very large numbers of matching
352 possibilities, it can become large very quickly with increasing length
353 of subject string. The match_limit_recursion number is a measure of how
354 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
355 memory is needed to complete the match attempt.
356
357 When \O is used, the value specified may be higher or lower than the
358 size set by the -O command line option (or defaulted to 45); \O applies
359 only to the call of pcre_exec() for the line in which it appears.
360
361 If the /P modifier was present on the pattern, causing the POSIX wrap-
362 per API to be used, the only option-setting sequences that have any
363 effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
364 to be passed to regexec().
365
366 The use of \x{hh...} to represent UTF-8 characters is not dependent on
367 the use of the /8 modifier on the pattern. It is recognized always.
368 There may be any number of hexadecimal digits inside the braces. The
369 result is from one to six bytes, encoded according to the UTF-8 rules.
370
371
372 THE ALTERNATIVE MATCHING FUNCTION
373
374 By default, pcretest uses the standard PCRE matching function,
375 pcre_exec() to match each data line. From release 6.0, PCRE supports an
376 alternative matching function, pcre_dfa_test(), which operates in a
377 different way, and has some restrictions. The differences between the
378 two functions are described in the pcrematching documentation.
379
380 If a data line contains the \D escape sequence, or if the command line
381 contains the -dfa option, the alternative matching function is called.
382 This function finds all possible matches at a given point. If, however,
383 the \F escape sequence is present in the data line, it stops after the
384 first match is found. This is always the shortest possible match.
385
386
387 DEFAULT OUTPUT FROM PCRETEST
388
389 This section describes the output when the normal matching function,
390 pcre_exec(), is being used.
391
392 When a match succeeds, pcretest outputs the list of captured substrings
393 that pcre_exec() returns, starting with number 0 for the string that
394 matched the whole pattern. Otherwise, it outputs "No match" or "Partial
395 match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
396 TIAL, respectively, and otherwise the PCRE negative error number. Here
397 is an example of an interactive pcretest run.
398
399 $ pcretest
400 PCRE version 7.0 30-Nov-2006
401
402 re> /^abc(\d+)/
403 data> abc123
404 0: abc123
405 1: 123
406 data> xyz
407 No match
408
409 If the strings contain any non-printing characters, they are output as
410 \0x escapes, or as \x{...} escapes if the /8 modifier was present on
411 the pattern. See below for the definition of non-printing characters.
412 If the pattern has the /+ modifier, the output for substring 0 is fol-
413 lowed by the the rest of the subject string, identified by "0+" like
414 this:
415
416 re> /cat/+
417 data> cataract
418 0: cat
419 0+ aract
420
421 If the pattern has the /g or /G modifier, the results of successive
422 matching attempts are output in sequence, like this:
423
424 re> /\Bi(\w\w)/g
425 data> Mississippi
426 0: iss
427 1: ss
428 0: iss
429 1: ss
430 0: ipp
431 1: pp
432
433 "No match" is output only if the first match attempt fails.
434
435 If any of the sequences \C, \G, or \L are present in a data line that
436 is successfully matched, the substrings extracted by the convenience
437 functions are output with C, G, or L after the string number instead of
438 a colon. This is in addition to the normal full list. The string length
439 (that is, the return from the extraction function) is given in paren-
440 theses after each string for \C and \G.
441
442 Note that whereas patterns can be continued over several lines (a plain
443 ">" prompt is used for continuations), data lines may not. However new-
444 lines can be included in data by means of the \n escape (or \r, \r\n,
445 etc., depending on the newline sequence setting).
446
447
448 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
449
450 When the alternative matching function, pcre_dfa_exec(), is used (by
451 means of the \D escape sequence or the -dfa command line option), the
452 output consists of a list of all the matches that start at the first
453 point in the subject where there is at least one match. For example:
454
455 re> /(tang|tangerine|tan)/
456 data> yellow tangerine\D
457 0: tangerine
458 1: tang
459 2: tan
460
461 (Using the normal matching function on this data finds only "tang".)
462 The longest matching string is always given first (and numbered zero).
463
464 If /g is present on the pattern, the search for further matches resumes
465 at the end of the longest match. For example:
466
467 re> /(tang|tangerine|tan)/g
468 data> yellow tangerine and tangy sultana\D
469 0: tangerine
470 1: tang
471 2: tan
472 0: tang
473 1: tan
474 0: tan
475
476 Since the matching function does not support substring capture, the
477 escape sequences that are concerned with captured substrings are not
478 relevant.
479
480
481 RESTARTING AFTER A PARTIAL MATCH
482
483 When the alternative matching function has given the PCRE_ERROR_PARTIAL
484 return, indicating that the subject partially matched the pattern, you
485 can restart the match with additional subject data by means of the \R
486 escape sequence. For example:
487
488 re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/
489 data> 23ja\P\D
490 Partial match: 23ja
491 data> n05\R\D
492 0: n05
493
494 For further information about partial matching, see the pcrepartial
495 documentation.
496
497
498 CALLOUTS
499
500 If the pattern contains any callout requests, pcretest's callout func-
501 tion is called during matching. This works with both matching func-
502 tions. By default, the called function displays the callout number, the
503 start and current positions in the text at the callout time, and the
504 next pattern item to be tested. For example, the output
505
506 --->pqrabcdef
507 0 ^ ^ \d
508
509 indicates that callout number 0 occurred for a match attempt starting
510 at the fourth character of the subject string, when the pointer was at
511 the seventh character of the data, and when the next pattern item was
512 \d. Just one circumflex is output if the start and current positions
513 are the same.
514
515 Callouts numbered 255 are assumed to be automatic callouts, inserted as
516 a result of the /C pattern modifier. In this case, instead of showing
517 the callout number, the offset in the pattern, preceded by a plus, is
518 output. For example:
519
520 re> /\d?[A-E]\*/C
521 data> E*
522 --->E*
523 +0 ^ \d?
524 +3 ^ [A-E]
525 +8 ^^ \*
526 +10 ^ ^
527 0: E*
528
529 The callout function in pcretest returns zero (carry on matching) by
530 default, but you can use a \C item in a data line (as described above)
531 to change this.
532
533 Inserting callouts can be helpful when using pcretest to check compli-
534 cated regular expressions. For further information about callouts, see
535 the pcrecallout documentation.
536
537
538 NON-PRINTING CHARACTERS
539
540 When pcretest is outputting text in the compiled version of a pattern,
541 bytes other than 32-126 are always treated as non-printing characters
542 are are therefore shown as hex escapes.
543
544 When pcretest is outputting text that is a matched part of a subject
545 string, it behaves in the same way, unless a different locale has been
546 set for the pattern (using the /L modifier). In this case, the
547 isprint() function to distinguish printing and non-printing characters.
548
549
550 SAVING AND RELOADING COMPILED PATTERNS
551
552 The facilities described in this section are not available when the
553 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
554 ifier is specified.
555
556 When the POSIX interface is not in use, you can cause pcretest to write
557 a compiled pattern to a file, by following the modifiers with > and a
558 file name. For example:
559
560 /pattern/im >/some/file
561
562 See the pcreprecompile documentation for a discussion about saving and
563 re-using compiled patterns.
564
565 The data that is written is binary. The first eight bytes are the
566 length of the compiled pattern data followed by the length of the
567 optional study data, each written as four bytes in big-endian order
568 (most significant byte first). If there is no study data (either the
569 pattern was not studied, or studying did not return any data), the sec-
570 ond length is zero. The lengths are followed by an exact copy of the
571 compiled pattern. If there is additional study data, this follows imme-
572 diately after the compiled pattern. After writing the file, pcretest
573 expects to read a new pattern.
574
575 A saved pattern can be reloaded into pcretest by specifing < and a file
576 name instead of a pattern. The name of the file must not contain a <
577 character, as otherwise pcretest will interpret the line as a pattern
578 delimited by < characters. For example:
579
580 re> </some/file
581 Compiled regex loaded from /some/file
582 No study data
583
584 When the pattern has been loaded, pcretest proceeds to read data lines
585 in the usual way.
586
587 You can copy a file written by pcretest to a different host and reload
588 it there, even if the new host has opposite endianness to the one on
589 which the pattern was compiled. For example, you can compile on an i86
590 machine and run on a SPARC machine.
591
592 File names for saving and reloading can be absolute or relative, but
593 note that the shell facility of expanding a file name that starts with
594 a tilde (~) is not available.
595
596 The ability to save and reload files in pcretest is intended for test-
597 ing and experimentation. It is not intended for production use because
598 only a single pattern can be written to a file. Furthermore, there is
599 no facility for supplying custom character tables for use with a
600 reloaded pattern. If the original pattern was compiled with custom
601 tables, an attempt to match a subject string using a reloaded pattern
602 is likely to cause pcretest to crash. Finally, if you attempt to load
603 a file that is not in the correct format, the result is undefined.
604
605
606 SEE ALSO
607
608 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
609 pcrepattern(3), pcreprecompile(3).
610
611
612 AUTHOR
613
614 Philip Hazel
615 University Computing Service
616 Cambridge CB2 3QH, England.
617
618
619 REVISION
620
621 Last updated: 06 March 2007
622 Copyright (c) 1997-2007 University of Cambridge.

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