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8ac170f3
PH		 1This file contains the PCRE man page that described the pcretest program. Note
2that not all of the features of PCRE are available in the limited version that
495ae4b0
PH		 3is built with Exim.
4-------------------------------------------------------------------------------
5
6PCRETEST(1) PCRETEST(1)
7
8
9
10NAME
11 pcretest - a program for testing Perl-compatible regular expressions.
12
13SYNOPSIS
14
8ac170f3 15 pcretest [-C] [-d] [-dfa] [-i] [-m] [-o osize] [-p] [-t] [source]
495ae4b0
PH		 16 [destination]
17
18 pcretest was written as a test program for the PCRE regular expression
19 library itself, but it can also be used for experimenting with regular
20 expressions. This document describes the features of the test program;
21 for details of the regular expressions themselves, see the pcrepattern
22 documentation. For details of the PCRE library function calls and their
23 options, see the pcreapi documentation.
24
25
26OPTIONS
27
28 -C Output the version number of the PCRE library, and all avail-
29 able information about the optional features that are
30 included, and then exit.
31
8ac170f3 32 -d Behave as if each regex has the /D (debug) modifier; the
495ae4b0
PH		 33 internal form is output after compilation.
34
8ac170f3
PH		 35 -dfa Behave as if each data line contains the \D escape sequence;
36 this causes the alternative matching function,
37 pcre_dfa_exec(), to be used instead of the standard
38 pcre_exec() function (more detail is given below).
39
40 -i Behave as if each regex has the /I modifier; information
495ae4b0
PH		 41 about the compiled pattern is given after compilation.
42
8ac170f3
PH		 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
495ae4b0
PH		 46 pcretest, -s is a synonym for -m.
47
8ac170f3
PH		 48 -o osize Set the number of elements in the output vector that is used
49 when calling pcre_exec() to be osize. The default value is
495ae4b0 50 45, which is enough for 14 capturing subexpressions. The vec-
8ac170f3 51 tor size can be changed for individual matching calls by
495ae4b0
PH		 52 including \O in the data line (see below).
53
8ac170f3
PH		 54 -p Behave as if each regex has the /P modifier; the POSIX wrap-
55 per API is used to call PCRE. None of the other options has
56 any effect when -p is set.
495ae4b0 57
8ac170f3
PH		 58 -t Run each compile, study, and match many times with a timer,
59 and output resulting time per compile or match (in millisec-
60 onds). Do not set -m with -t, because you will then get the
61 size output a zillion times, and the timing will be dis-
495ae4b0
PH		 62 torted.
63
64
65DESCRIPTION
66
8ac170f3 67 If pcretest is given two filename arguments, it reads from the first
495ae4b0 68 and writes to the second. If it is given only one filename argument, it
8ac170f3
PH		 69 reads from that file and writes to stdout. Otherwise, it reads from
70 stdin and writes to stdout, and prompts for each line of input, using
495ae4b0
PH		 71 "re>" to prompt for regular expressions, and "data>" to prompt for data
72 lines.
73
74 The program handles any number of sets of input on a single input file.
8ac170f3 75 Each set starts with a regular expression, and continues with any num-
495ae4b0
PH		 76 ber of data lines to be matched against the pattern.
77
8ac170f3
PH		 78 Each data line is matched separately and independently. If you want to
79 do multiple-line matches, you have to use the \n escape sequence in a
80 single line of input to encode the newline characters. The maximum
495ae4b0
PH		 81 length of data line is 30,000 characters.
82
8ac170f3
PH		 83 An empty line signals the end of the data lines, at which point a new
84 regular expression is read. The regular expressions are given enclosed
495ae4b0
PH		 85 in any non-alphanumeric delimiters other than backslash, for example
86
87 /(a|bc)x+yz/
88
8ac170f3
PH		 89 White space before the initial delimiter is ignored. A regular expres-
90 sion may be continued over several input lines, in which case the new-
91 line characters are included within it. It is possible to include the
495ae4b0
PH		 92 delimiter within the pattern by escaping it, for example
93
94 /abc\/def/
95
8ac170f3
PH		 96 If you do so, the escape and the delimiter form part of the pattern,
97 but since delimiters are always non-alphanumeric, this does not affect
98 its interpretation. If the terminating delimiter is immediately fol-
495ae4b0
PH		 99 lowed by a backslash, for example,
100
101 /abc/\
102
8ac170f3
PH		 103 then a backslash is added to the end of the pattern. This is done to
104 provide a way of testing the error condition that arises if a pattern
495ae4b0
PH		 105 finishes with a backslash, because
106
107 /abc\/
108
8ac170f3 109 is interpreted as the first line of a pattern that starts with "abc/",
495ae4b0
PH		 110 causing pcretest to read the next line as a continuation of the regular
111 expression.
112
113
114PATTERN MODIFIERS
115
8ac170f3
PH		 116 A pattern may be followed by any number of modifiers, which are mostly
117 single characters. Following Perl usage, these are referred to below
118 as, for example, "the /i modifier", even though the delimiter of the
119 pattern need not always be a slash, and no slash is used when writing
120 modifiers. Whitespace may appear between the final pattern delimiter
495ae4b0
PH		 121 and the first modifier, and between the modifiers themselves.
122
123 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
8ac170f3
PH		 124 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
125 pile() is called. These four modifier letters have the same effect as
495ae4b0
PH		 126 they do in Perl. For example:
127
128 /caseless/i
129
130 The following table shows additional modifiers for setting PCRE options
131 that do not correspond to anything in Perl:
132
133 /A PCRE_ANCHORED
134 /C PCRE_AUTO_CALLOUT
135 /E PCRE_DOLLAR_ENDONLY
8ac170f3 136 /f PCRE_FIRSTLINE
495ae4b0
PH		 137 /N PCRE_NO_AUTO_CAPTURE
138 /U PCRE_UNGREEDY
139 /X PCRE_EXTRA
140
8ac170f3
PH		 141 Searching for all possible matches within each subject string can be
142 requested by the /g or /G modifier. After finding a match, PCRE is
495ae4b0
PH		 143 called again to search the remainder of the subject string. The differ-
144 ence between /g and /G is that the former uses the startoffset argument
8ac170f3
PH		 145 to pcre_exec() to start searching at a new point within the entire
146 string (which is in effect what Perl does), whereas the latter passes
147 over a shortened substring. This makes a difference to the matching
495ae4b0
PH		 148 process if the pattern begins with a lookbehind assertion (including \b
149 or \B).
150
8ac170f3
PH		 151 If any call to pcre_exec() in a /g or /G sequence matches an empty
152 string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
153 flags set in order to search for another, non-empty, match at the same
154 point. If this second match fails, the start offset is advanced by
155 one, and the normal match is retried. This imitates the way Perl han-
495ae4b0
PH		 156 dles such cases when using the /g modifier or the split() function.
157
158 There are yet more modifiers for controlling the way pcretest operates.
159
8ac170f3
PH		 160 The /+ modifier requests that as well as outputting the substring that
161 matched the entire pattern, pcretest should in addition output the
162 remainder of the subject string. This is useful for tests where the
495ae4b0
PH		 163 subject contains multiple copies of the same substring.
164
8ac170f3 165 The /L modifier must be followed directly by the name of a locale, for
495ae4b0
PH		 166 example,
167
168 /pattern/Lfr_FR
169
170 For this reason, it must be the last modifier. The given locale is set,
8ac170f3
PH		 171 pcre_maketables() is called to build a set of character tables for the
172 locale, and this is then passed to pcre_compile() when compiling the
173 regular expression. Without an /L modifier, NULL is passed as the
174 tables pointer; that is, /L applies only to the expression on which it
495ae4b0
PH		 175 appears.
176
8ac170f3
PH		 177 The /I modifier requests that pcretest output information about the
178 compiled pattern (whether it is anchored, has a fixed first character,
179 and so on). It does this by calling pcre_fullinfo() after compiling a
180 pattern. If the pattern is studied, the results of that are also out-
495ae4b0
PH		 181 put.
182
183 The /D modifier is a PCRE debugging feature, which also assumes /I. It
8ac170f3 184 causes the internal form of compiled regular expressions to be output
495ae4b0
PH		 185 after compilation. If the pattern was studied, the information returned
186 is also output.
187
188 The /F modifier causes pcretest to flip the byte order of the fields in
8ac170f3
PH		 189 the compiled pattern that contain 2-byte and 4-byte numbers. This
190 facility is for testing the feature in PCRE that allows it to execute
495ae4b0 191 patterns that were compiled on a host with a different endianness. This
8ac170f3
PH		 192 feature is not available when the POSIX interface to PCRE is being
193 used, that is, when the /P pattern modifier is specified. See also the
495ae4b0
PH		 194 section about saving and reloading compiled patterns below.
195
8ac170f3 196 The /S modifier causes pcre_study() to be called after the expression
495ae4b0
PH		 197 has been compiled, and the results used when the expression is matched.
198
8ac170f3 199 The /M modifier causes the size of memory block used to hold the com-
495ae4b0
PH		 200 piled pattern to be output.
201
8ac170f3
PH		 202 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
203 rather than its native API. When this is done, all other modifiers
204 except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
205 and REG_NEWLINE is set if /m is present. The wrapper functions force
206 PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
495ae4b0 207
8ac170f3
PH		 208 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
209 set. This turns on support for UTF-8 character handling in PCRE, pro-
210 vided that it was compiled with this support enabled. This modifier
495ae4b0
PH		 211 also causes any non-printing characters in output strings to be printed
212 using the \x{hh...} notation if they are valid UTF-8 sequences.
213
8ac170f3
PH		 214 If the /? modifier is used with /8, it causes pcretest to call
215 pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
495ae4b0
PH		 216 checking of the string for UTF-8 validity.
217
218
219DATA LINES
220
8ac170f3
PH		 221 Before each data line is passed to pcre_exec(), leading and trailing
222 whitespace is removed, and it is then scanned for \ escapes. Some of
223 these are pretty esoteric features, intended for checking out some of
224 the more complicated features of PCRE. If you are just testing "ordi-
225 nary" regular expressions, you probably don't need any of these. The
495ae4b0
PH		 226 following escapes are recognized:
227
228 \a alarm (= BEL)
229 \b backspace
230 \e escape
231 \f formfeed
232 \n newline
233 \r carriage return
234 \t tab
235 \v vertical tab
236 \nnn octal character (up to 3 octal digits)
237 \xhh hexadecimal character (up to 2 hex digits)
238 \x{hh...} hexadecimal character, any number of digits
239 in UTF-8 mode
240 \A pass the PCRE_ANCHORED option to pcre_exec()
241 \B pass the PCRE_NOTBOL option to pcre_exec()
242 \Cdd call pcre_copy_substring() for substring dd
243 after a successful match (number less than 32)
244 \Cname call pcre_copy_named_substring() for substring
245 "name" after a successful match (name termin-
246 ated by next non alphanumeric character)
247 \C+ show the current captured substrings at callout
248 time
249 \C- do not supply a callout function
250 \C!n return 1 instead of 0 when callout number n is
251 reached
252 \C!n!m return 1 instead of 0 when callout number n is
253 reached for the nth time
254 \C*n pass the number n (may be negative) as callout
255 data; this is used as the callout return value
8ac170f3
PH		 256 \D use the pcre_dfa_exec() match function
257 \F only shortest match for pcre_dfa_exec()
495ae4b0
PH		 258 \Gdd call pcre_get_substring() for substring dd
259 after a successful match (number less than 32)
260 \Gname call pcre_get_named_substring() for substring
261 "name" after a successful match (name termin-
262 ated by next non-alphanumeric character)
263 \L call pcre_get_substringlist() after a
264 successful match
265 \M discover the minimum MATCH_LIMIT setting
266 \N pass the PCRE_NOTEMPTY option to pcre_exec()
267 \Odd set the size of the output vector passed to
268 pcre_exec() to dd (any number of digits)
269 \P pass the PCRE_PARTIAL option to pcre_exec()
8ac170f3
PH		 270 or pcre_dfa_exec()
271 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
495ae4b0
PH		 272 \S output details of memory get/free calls during matching
273 \Z pass the PCRE_NOTEOL option to pcre_exec()
274 \? pass the PCRE_NO_UTF8_CHECK option to
275 pcre_exec()
276 \>dd start the match at offset dd (any number of digits);
277 this sets the startoffset argument for pcre_exec()
278
8ac170f3
PH		 279 A backslash followed by anything else just escapes the anything else.
280 If the very last character is a backslash, it is ignored. This gives a
281 way of passing an empty line as data, since a real empty line termi-
495ae4b0
PH		 282 nates the data input.
283
8ac170f3
PH		 284 If \M is present, pcretest calls pcre_exec() several times, with dif-
285 ferent values in the match_limit field of the pcre_extra data struc-
286 ture, until it finds the minimum number that is needed for pcre_exec()
287 to complete. This number is a measure of the amount of recursion and
288 backtracking that takes place, and checking it out can be instructive.
289 For most simple matches, the number is quite small, but for patterns
290 with very large numbers of matching possibilities, it can become large
495ae4b0
PH		 291 very quickly with increasing length of subject string.
292
8ac170f3 293 When \O is used, the value specified may be higher or lower than the
495ae4b0
PH		 294 size set by the -O command line option (or defaulted to 45); \O applies
295 only to the call of pcre_exec() for the line in which it appears.
296
8ac170f3
PH		 297 If the /P modifier was present on the pattern, causing the POSIX wrap-
298 per API to be used, only \B and \Z have any effect, causing REG_NOTBOL
495ae4b0
PH		 299 and REG_NOTEOL to be passed to regexec() respectively.
300
8ac170f3
PH		 301 The use of \x{hh...} to represent UTF-8 characters is not dependent on
302 the use of the /8 modifier on the pattern. It is recognized always.
303 There may be any number of hexadecimal digits inside the braces. The
304 result is from one to six bytes, encoded according to the UTF-8 rules.
305
306
307THE ALTERNATIVE MATCHING FUNCTION
308
309 By default, pcretest uses the standard PCRE matching function,
310 pcre_exec() to match each data line. From release 6.0, PCRE supports an
311 alternative matching function, pcre_dfa_test(), which operates in a
312 different way, and has some restrictions. The differences between the
313 two functions are described in the pcrematching documentation.
314
315 If a data line contains the \D escape sequence, or if the command line
316 contains the -dfa option, the alternative matching function is called.
317 This function finds all possible matches at a given point. If, however,
318 the \F escape sequence is present in the data line, it stops after the
319 first match is found. This is always the shortest possible match.
495ae4b0
PH		 320
321
8ac170f3
PH		 322DEFAULT OUTPUT FROM PCRETEST
323
324 This section describes the output when the normal matching function,
325 pcre_exec(), is being used.
495ae4b0
PH		 326
327 When a match succeeds, pcretest outputs the list of captured substrings
328 that pcre_exec() returns, starting with number 0 for the string that
329 matched the whole pattern. Otherwise, it outputs "No match" or "Partial
330 match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
331 TIAL, respectively, and otherwise the PCRE negative error number. Here
332 is an example of an interactive pcretest run.
333
334 $ pcretest
335 PCRE version 5.00 07-Sep-2004
336
337 re> /^abc(\d+)/
338 data> abc123
339 0: abc123
340 1: 123
341 data> xyz
342 No match
343
344 If the strings contain any non-printing characters, they are output as
345 \0x escapes, or as \x{...} escapes if the /8 modifier was present on
346 the pattern. If the pattern has the /+ modifier, the output for sub-
347 string 0 is followed by the the rest of the subject string, identified
348 by "0+" like this:
349
350 re> /cat/+
351 data> cataract
352 0: cat
353 0+ aract
354
355 If the pattern has the /g or /G modifier, the results of successive
356 matching attempts are output in sequence, like this:
357
358 re> /\Bi(\w\w)/g
359 data> Mississippi
360 0: iss
361 1: ss
362 0: iss
363 1: ss
364 0: ipp
365 1: pp
366
367 "No match" is output only if the first match attempt fails.
368
369 If any of the sequences \C, \G, or \L are present in a data line that
370 is successfully matched, the substrings extracted by the convenience
371 functions are output with C, G, or L after the string number instead of
372 a colon. This is in addition to the normal full list. The string length
373 (that is, the return from the extraction function) is given in paren-
374 theses after each string for \C and \G.
375
376 Note that while patterns can be continued over several lines (a plain
377 ">" prompt is used for continuations), data lines may not. However new-
378 lines can be included in data by means of the \n escape.
379
380
8ac170f3
PH		 381OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
382
383 When the alternative matching function, pcre_dfa_exec(), is used (by
384 means of the \D escape sequence or the -dfa command line option), the
385 output consists of a list of all the matches that start at the first
386 point in the subject where there is at least one match. For example:
387
388 re> /(tang|tangerine|tan)/
389 data> yellow tangerine\D
390 0: tangerine
391 1: tang
392 2: tan
393
394 (Using the normal matching function on this data finds only "tang".)
395 The longest matching string is always given first (and numbered zero).
396
397 If /gP is present on the pattern, the search for further matches
398 resumes at the end of the longest match. For example:
399
400 re> /(tang|tangerine|tan)/g
401 data> yellow tangerine and tangy sultana\D
402 0: tangerine
403 1: tang
404 2: tan
405 0: tang
406 1: tan
407 0: tan
408
409 Since the matching function does not support substring capture, the
410 escape sequences that are concerned with captured substrings are not
411 relevant.
412
413
414RESTARTING AFTER A PARTIAL MATCH
415
416 When the alternative matching function has given the PCRE_ERROR_PARTIAL
417 return, indicating that the subject partially matched the pattern, you
418 can restart the match with additional subject data by means of the \R
419 escape sequence. For example:
420
421 re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/
422 data> 23ja\P\D
423 Partial match: 23ja
424 data> n05\R\D
425 0: n05
426
427 For further information about partial matching, see the pcrepartial
428 documentation.
429
430
495ae4b0
PH		 431CALLOUTS
432
433 If the pattern contains any callout requests, pcretest's callout func-
8ac170f3
PH		 434 tion is called during matching. This works with both matching func-
435 tions. By default, the called function displays the callout number, the
436 start and current positions in the text at the callout time, and the
437 next pattern item to be tested. For example, the output
495ae4b0
PH		 438
439 --->pqrabcdef
440 0 ^ ^ \d
441
8ac170f3
PH		 442 indicates that callout number 0 occurred for a match attempt starting
443 at the fourth character of the subject string, when the pointer was at
444 the seventh character of the data, and when the next pattern item was
445 \d. Just one circumflex is output if the start and current positions
495ae4b0
PH		 446 are the same.
447
448 Callouts numbered 255 are assumed to be automatic callouts, inserted as
8ac170f3
PH		 449 a result of the /C pattern modifier. In this case, instead of showing
450 the callout number, the offset in the pattern, preceded by a plus, is
495ae4b0
PH		 451 output. For example:
452
453 re> /\d?[A-E]\*/C
454 data> E*
455 --->E*
456 +0 ^ \d?
457 +3 ^ [A-E]
458 +8 ^^ \*
459 +10 ^ ^
460 0: E*
461
8ac170f3
PH		 462 The callout function in pcretest returns zero (carry on matching) by
463 default, but you can use a \C item in a data line (as described above)
495ae4b0
PH		 464 to change this.
465
8ac170f3
PH		 466 Inserting callouts can be helpful when using pcretest to check compli-
467 cated regular expressions. For further information about callouts, see
495ae4b0
PH		 468 the pcrecallout documentation.
469
470
471SAVING AND RELOADING COMPILED PATTERNS
472
8ac170f3 473 The facilities described in this section are not available when the
495ae4b0
PH		 474 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
475 ifier is specified.
476
477 When the POSIX interface is not in use, you can cause pcretest to write
8ac170f3 478 a compiled pattern to a file, by following the modifiers with > and a
495ae4b0
PH		 479 file name. For example:
480
481 /pattern/im >/some/file
482
8ac170f3 483 See the pcreprecompile documentation for a discussion about saving and
495ae4b0
PH		 484 re-using compiled patterns.
485
8ac170f3
PH		 486 The data that is written is binary. The first eight bytes are the
487 length of the compiled pattern data followed by the length of the
488 optional study data, each written as four bytes in big-endian order
489 (most significant byte first). If there is no study data (either the
495ae4b0 490 pattern was not studied, or studying did not return any data), the sec-
8ac170f3 491 ond length is zero. The lengths are followed by an exact copy of the
495ae4b0 492 compiled pattern. If there is additional study data, this follows imme-
8ac170f3 493 diately after the compiled pattern. After writing the file, pcretest
495ae4b0
PH		 494 expects to read a new pattern.
495
496 A saved pattern can be reloaded into pcretest by specifing < and a file
8ac170f3
PH		 497 name instead of a pattern. The name of the file must not contain a <
498 character, as otherwise pcretest will interpret the line as a pattern
495ae4b0
PH		 499 delimited by < characters. For example:
500
501 re> </some/file
502 Compiled regex loaded from /some/file
503 No study data
504
8ac170f3 505 When the pattern has been loaded, pcretest proceeds to read data lines
495ae4b0
PH		 506 in the usual way.
507
8ac170f3
PH		 508 You can copy a file written by pcretest to a different host and reload
509 it there, even if the new host has opposite endianness to the one on
510 which the pattern was compiled. For example, you can compile on an i86
495ae4b0
PH		 511 machine and run on a SPARC machine.
512
8ac170f3
PH		 513 File names for saving and reloading can be absolute or relative, but
514 note that the shell facility of expanding a file name that starts with
495ae4b0
PH		 515 a tilde (~) is not available.
516
8ac170f3
PH		 517 The ability to save and reload files in pcretest is intended for test-
518 ing and experimentation. It is not intended for production use because
519 only a single pattern can be written to a file. Furthermore, there is
520 no facility for supplying custom character tables for use with a
521 reloaded pattern. If the original pattern was compiled with custom
522 tables, an attempt to match a subject string using a reloaded pattern
523 is likely to cause pcretest to crash. Finally, if you attempt to load
495ae4b0
PH		 524 a file that is not in the correct format, the result is undefined.
525
526
527AUTHOR
528
8ac170f3 529 Philip Hazel
495ae4b0
PH		 530 University Computing Service,
531 Cambridge CB2 3QG, England.
532
8ac170f3
PH		 533Last updated: 28 February 2005
534Copyright (c) 1997-2005 University of Cambridge.
Unnamed repository; edit this file 'description' to name the repository.