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

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