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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] [input file [output file]]
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. The input for pcretest is a
18 sequence of regular expression patterns and strings to be matched, as
19 described below. The output shows the result of each match. Options on
20 the command line and the patterns control PCRE options and exactly what
21 is output.
22
23
24 COMMAND LINE OPTIONS
25
26 -b Behave as if each pattern has the /B (show byte code) modi-
27 fier; the internal form is output after compilation.
28
29 -C Output the version number of the PCRE library, and all avail-
30 able information about the optional features that are
31 included, and then exit.
32
33 -d Behave as if each pattern has the /D (debug) modifier; the
34 internal form and information about the compiled pattern is
35 output after compilation; -d is equivalent to -b -i.
36
37 -dfa Behave as if each data line contains the \D escape sequence;
38 this causes the alternative matching function,
39 pcre_dfa_exec(), to be used instead of the standard
40 pcre_exec() function (more detail is given below).
41
42 -help Output a brief summary these options and then exit.
43
44 -i Behave as if each pattern has the /I modifier; information
45 about the compiled pattern is given after compilation.
46
47 -M Behave as if each data line contains the \M escape sequence;
48 this causes PCRE to discover the minimum MATCH_LIMIT and
49 MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
50 edly with different limits.
51
52 -m Output the size of each compiled pattern after it has been
53 compiled. This is equivalent to adding /M to each regular
54 expression.
55
56 -o osize Set the number of elements in the output vector that is used
57 when calling pcre_exec() or pcre_dfa_exec() to be osize. The
58 default value is 45, which is enough for 14 capturing subex-
59 pressions for pcre_exec() or 22 different matches for
60 pcre_dfa_exec(). The vector size can be changed for individ-
61 ual matching calls by including \O in the data line (see
62 below).
63
64 -p Behave as if each pattern has the /P modifier; the POSIX
65 wrapper API is used to call PCRE. None of the other options
66 has any effect when -p is set.
67
68 -q Do not output the version number of pcretest at the start of
69 execution.
70
71 -S size On Unix-like systems, set the size of the run-time stack to
72 size megabytes.
73
74 -s or -s+ Behave as if each pattern has the /S modifier; in other
75 words, force each pattern to be studied. If -s+ is used, the
76 PCRE_STUDY_JIT_COMPILE flag is passed to pcre_study(), caus-
77 ing just-in-time optimization to be set up if it is avail-
78 able. If the /I or /D option is present on a pattern
79 (requesting output about the compiled pattern), information
80 about the result of studying is not included when studying is
81 caused only by -s and neither -i nor -d is present on the
82 command line. This behaviour means that the output from tests
83 that are run with and without -s should be identical, except
84 when options that output information about the actual running
85 of a match are set. The -M, -t, and -tm options, which give
86 information about resources used, are likely to produce dif-
87 ferent output with and without -s. Output may also differ if
88 the /C option is present on an individual pattern. This uses
89 callouts to trace the the matching process, and this may be
90 different between studied and non-studied patterns. If the
91 pattern contains (*MARK) items there may also be differences,
92 for the same reason. The -s command line option can be over-
93 ridden for specific patterns that should never be studied
94 (see the /S pattern modifier below).
95
96 -t Run each compile, study, and match many times with a timer,
97 and output resulting time per compile or match (in millisec-
98 onds). Do not set -m with -t, because you will then get the
99 size output a zillion times, and the timing will be dis-
100 torted. You can control the number of iterations that are
101 used for timing by following -t with a number (as a separate
102 item on the command line). For example, "-t 1000" would iter-
103 ate 1000 times. The default is to iterate 500000 times.
104
105 -tm This is like -t except that it times only the matching phase,
106 not the compile or study phases.
107
108
109 DESCRIPTION
110
111 If pcretest is given two filename arguments, it reads from the first
112 and writes to the second. If it is given only one filename argument, it
113 reads from that file and writes to stdout. Otherwise, it reads from
114 stdin and writes to stdout, and prompts for each line of input, using
115 "re>" to prompt for regular expressions, and "data>" to prompt for data
116 lines.
117
118 When pcretest is built, a configuration option can specify that it
119 should be linked with the libreadline library. When this is done, if
120 the input is from a terminal, it is read using the readline() function.
121 This provides line-editing and history facilities. The output from the
122 -help option states whether or not readline() will be used.
123
124 The program handles any number of sets of input on a single input file.
125 Each set starts with a regular expression, and continues with any num-
126 ber of data lines to be matched against the pattern.
127
128 Each data line is matched separately and independently. If you want to
129 do multi-line matches, you have to use the \n escape sequence (or \r or
130 \r\n, etc., depending on the newline setting) in a single line of input
131 to encode the newline sequences. There is no limit on the length of
132 data lines; the input buffer is automatically extended if it is too
133 small.
134
135 An empty line signals the end of the data lines, at which point a new
136 regular expression is read. The regular expressions are given enclosed
137 in any non-alphanumeric delimiters other than backslash, for example:
138
139 /(a|bc)x+yz/
140
141 White space before the initial delimiter is ignored. A regular expres-
142 sion may be continued over several input lines, in which case the new-
143 line characters are included within it. It is possible to include the
144 delimiter within the pattern by escaping it, for example
145
146 /abc\/def/
147
148 If you do so, the escape and the delimiter form part of the pattern,
149 but since delimiters are always non-alphanumeric, this does not affect
150 its interpretation. If the terminating delimiter is immediately fol-
151 lowed by a backslash, for example,
152
153 /abc/\
154
155 then a backslash is added to the end of the pattern. This is done to
156 provide a way of testing the error condition that arises if a pattern
157 finishes with a backslash, because
158
159 /abc\/
160
161 is interpreted as the first line of a pattern that starts with "abc/",
162 causing pcretest to read the next line as a continuation of the regular
163 expression.
164
165
166 PATTERN MODIFIERS
167
168 A pattern may be followed by any number of modifiers, which are mostly
169 single characters. Following Perl usage, these are referred to below
170 as, for example, "the /i modifier", even though the delimiter of the
171 pattern need not always be a slash, and no slash is used when writing
172 modifiers. White space may appear between the final pattern delimiter
173 and the first modifier, and between the modifiers themselves.
174
175 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
176 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
177 pile() is called. These four modifier letters have the same effect as
178 they do in Perl. For example:
179
180 /caseless/i
181
182 The following table shows additional modifiers for setting PCRE com-
183 pile-time options that do not correspond to anything in Perl:
184
185 /8 PCRE_UTF8
186 /? PCRE_NO_UTF8_CHECK
187 /A PCRE_ANCHORED
188 /C PCRE_AUTO_CALLOUT
189 /E PCRE_DOLLAR_ENDONLY
190 /f PCRE_FIRSTLINE
191 /J PCRE_DUPNAMES
192 /N PCRE_NO_AUTO_CAPTURE
193 /U PCRE_UNGREEDY
194 /W PCRE_UCP
195 /X PCRE_EXTRA
196 /Y PCRE_NO_START_OPTIMIZE
197 /<JS> PCRE_JAVASCRIPT_COMPAT
198 /<cr> PCRE_NEWLINE_CR
199 /<lf> PCRE_NEWLINE_LF
200 /<crlf> PCRE_NEWLINE_CRLF
201 /<anycrlf> PCRE_NEWLINE_ANYCRLF
202 /<any> PCRE_NEWLINE_ANY
203 /<bsr_anycrlf> PCRE_BSR_ANYCRLF
204 /<bsr_unicode> PCRE_BSR_UNICODE
205
206 The modifiers that are enclosed in angle brackets are literal strings
207 as shown, including the angle brackets, but the letters within can be
208 in either case. This example sets multiline matching with CRLF as the
209 line ending sequence:
210
211 /^abc/m<CRLF>
212
213 As well as turning on the PCRE_UTF8 option, the /8 modifier also causes
214 any non-printing characters in output strings to be printed using the
215 \x{hh...} notation if they are valid UTF-8 sequences. Full details of
216 the PCRE options are given in the pcreapi documentation.
217
218 Finding all matches in a string
219
220 Searching for all possible matches within each subject string can be
221 requested by the /g or /G modifier. After finding a match, PCRE is
222 called again to search the remainder of the subject string. The differ-
223 ence between /g and /G is that the former uses the startoffset argument
224 to pcre_exec() to start searching at a new point within the entire
225 string (which is in effect what Perl does), whereas the latter passes
226 over a shortened substring. This makes a difference to the matching
227 process if the pattern begins with a lookbehind assertion (including \b
228 or \B).
229
230 If any call to pcre_exec() in a /g or /G sequence matches an empty
231 string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
232 PCRE_ANCHORED flags set in order to search for another, non-empty,
233 match at the same point. If this second match fails, the start offset
234 is advanced, and the normal match is retried. This imitates the way
235 Perl handles such cases when using the /g modifier or the split() func-
236 tion. Normally, the start offset is advanced by one character, but if
237 the newline convention recognizes CRLF as a newline, and the current
238 character is CR followed by LF, an advance of two is used.
239
240 Other modifiers
241
242 There are yet more modifiers for controlling the way pcretest operates.
243
244 The /+ modifier requests that as well as outputting the substring that
245 matched the entire pattern, pcretest should in addition output the
246 remainder of the subject string. This is useful for tests where the
247 subject contains multiple copies of the same substring. If the + modi-
248 fier appears twice, the same action is taken for captured substrings.
249 In each case the remainder is output on the following line with a plus
250 character following the capture number. Note that this modifier must
251 not immediately follow the /S modifier because /S+ has another meaning.
252
253 The /= modifier requests that the values of all potential captured
254 parentheses be output after a match by pcre_exec(). By default, only
255 those up to the highest one actually used in the match are output (cor-
256 responding to the return code from pcre_exec()). Values in the offsets
257 vector corresponding to higher numbers should be set to -1, and these
258 are output as "<unset>". This modifier gives a way of checking that
259 this is happening.
260
261 The /B modifier is a debugging feature. It requests that pcretest out-
262 put a representation of the compiled byte code after compilation. Nor-
263 mally this information contains length and offset values; however, if
264 /Z is also present, this data is replaced by spaces. This is a special
265 feature for use in the automatic test scripts; it ensures that the same
266 output is generated for different internal link sizes.
267
268 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
269 that is, both the /B and the /I modifiers.
270
271 The /F modifier causes pcretest to flip the byte order of the fields in
272 the compiled pattern that contain 2-byte and 4-byte numbers. This
273 facility is for testing the feature in PCRE that allows it to execute
274 patterns that were compiled on a host with a different endianness. This
275 feature is not available when the POSIX interface to PCRE is being
276 used, that is, when the /P pattern modifier is specified. See also the
277 section about saving and reloading compiled patterns below.
278
279 The /I modifier requests that pcretest output information about the
280 compiled pattern (whether it is anchored, has a fixed first character,
281 and so on). It does this by calling pcre_fullinfo() after compiling a
282 pattern. If the pattern is studied, the results of that are also out-
283 put.
284
285 The /K modifier requests pcretest to show names from backtracking con-
286 trol verbs that are returned from calls to pcre_exec(). It causes
287 pcretest to create a pcre_extra block if one has not already been cre-
288 ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
289 the mark field within it, every time that pcre_exec() is called. If the
290 variable that the mark field points to is non-NULL for a match, non-
291 match, or partial match, pcretest prints the string to which it points.
292 For a match, this is shown on a line by itself, tagged with "MK:". For
293 a non-match it is added to the message.
294
295 The /L modifier must be followed directly by the name of a locale, for
296 example,
297
298 /pattern/Lfr_FR
299
300 For this reason, it must be the last modifier. The given locale is set,
301 pcre_maketables() is called to build a set of character tables for the
302 locale, and this is then passed to pcre_compile() when compiling the
303 regular expression. Without an /L (or /T) modifier, NULL is passed as
304 the tables pointer; that is, /L applies only to the expression on which
305 it appears.
306
307 The /M modifier causes the size of memory block used to hold the com-
308 piled pattern to be output.
309
310 If the /S modifier appears once, it causes pcre_study() to be called
311 after the expression has been compiled, and the results used when the
312 expression is matched. If /S appears twice, it suppresses studying,
313 even if it was requested externally by the -s command line option. This
314 makes it possible to specify that certain patterns are always studied,
315 and others are never studied, independently of -s. This feature is used
316 in the test files in a few cases where the output is different when the
317 pattern is studied.
318
319 If the /S modifier is immediately followed by a + character, the call
320 to pcre_study() is made with the PCRE_STUDY_JIT_COMPILE option,
321 requesting just-in-time optimization support if it is available. Note
322 that there is also a /+ modifier; it must not be given immediately
323 after /S because this will be misinterpreted. If JIT studying is suc-
324 cessful, it will automatically be used when pcre_exec() is run, except
325 when incompatible run-time options are specified. These include the
326 partial matching options; a complete list is given in the pcrejit docu-
327 mentation. See also the \J escape sequence below for a way of setting
328 the size of the JIT stack.
329
330 The /T modifier must be followed by a single digit. It causes a spe-
331 cific set of built-in character tables to be passed to pcre_compile().
332 It is used in the standard PCRE tests to check behaviour with different
333 character tables. The digit specifies the tables as follows:
334
335 0 the default ASCII tables, as distributed in
336 pcre_chartables.c.dist
337 1 a set of tables defining ISO 8859 characters
338
339 In table 1, some characters whose codes are greater than 128 are iden-
340 tified as letters, digits, spaces, etc.
341
342 Using the POSIX wrapper API
343
344 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
345 rather than its native API. When /P is set, the following modifiers set
346 options for the regcomp() function:
347
348 /i REG_ICASE
349 /m REG_NEWLINE
350 /N REG_NOSUB
351 /s REG_DOTALL )
352 /U REG_UNGREEDY ) These options are not part of
353 /W REG_UCP ) the POSIX standard
354 /8 REG_UTF8 )
355
356 The /+ modifier works as described above. All other modifiers are
357 ignored.
358
359
360 DATA LINES
361
362 Before each data line is passed to pcre_exec(), leading and trailing
363 white space is removed, and it is then scanned for \ escapes. Some of
364 these are pretty esoteric features, intended for checking out some of
365 the more complicated features of PCRE. If you are just testing "ordi-
366 nary" regular expressions, you probably don't need any of these. The
367 following escapes are recognized:
368
369 \a alarm (BEL, \x07)
370 \b backspace (\x08)
371 \e escape (\x27)
372 \f form feed (\x0c)
373 \n newline (\x0a)
374 \qdd set the PCRE_MATCH_LIMIT limit to dd
375 (any number of digits)
376 \r carriage return (\x0d)
377 \t tab (\x09)
378 \v vertical tab (\x0b)
379 \nnn octal character (up to 3 octal digits)
380 always a byte unless > 255 in UTF-8 mode
381 \xhh hexadecimal byte (up to 2 hex digits)
382 \x{hh...} hexadecimal character, any number of digits
383 in UTF-8 mode
384 \A pass the PCRE_ANCHORED option to pcre_exec()
385 or pcre_dfa_exec()
386 \B pass the PCRE_NOTBOL option to pcre_exec()
387 or pcre_dfa_exec()
388 \Cdd call pcre_copy_substring() for substring dd
389 after a successful match (number less than 32)
390 \Cname call pcre_copy_named_substring() for substring
391 "name" after a successful match (name termin-
392 ated by next non alphanumeric character)
393 \C+ show the current captured substrings at callout
394 time
395 \C- do not supply a callout function
396 \C!n return 1 instead of 0 when callout number n is
397 reached
398 \C!n!m return 1 instead of 0 when callout number n is
399 reached for the nth time
400 \C*n pass the number n (may be negative) as callout
401 data; this is used as the callout return value
402 \D use the pcre_dfa_exec() match function
403 \F only shortest match for pcre_dfa_exec()
404 \Gdd call pcre_get_substring() for substring dd
405 after a successful match (number less than 32)
406 \Gname call pcre_get_named_substring() for substring
407 "name" after a successful match (name termin-
408 ated by next non-alphanumeric character)
409 \Jdd set up a JIT stack of dd kilobytes maximum (any
410 number of digits)
411 \L call pcre_get_substringlist() after a
412 successful match
413 \M discover the minimum MATCH_LIMIT and
414 MATCH_LIMIT_RECURSION settings
415 \N pass the PCRE_NOTEMPTY option to pcre_exec()
416 or pcre_dfa_exec(); if used twice, pass the
417 PCRE_NOTEMPTY_ATSTART option
418 \Odd set the size of the output vector passed to
419 pcre_exec() to dd (any number of digits)
420 \P pass the PCRE_PARTIAL_SOFT option to pcre_exec()
421 or pcre_dfa_exec(); if used twice, pass the
422 PCRE_PARTIAL_HARD option
423 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
424 (any number of digits)
425 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
426 \S output details of memory get/free calls during matching
427 \Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
428 or pcre_dfa_exec()
429 \Z pass the PCRE_NOTEOL option to pcre_exec()
430 or pcre_dfa_exec()
431 \? pass the PCRE_NO_UTF8_CHECK option to
432 pcre_exec() or pcre_dfa_exec()
433 \>dd start the match at offset dd (optional "-"; then
434 any number of digits); this sets the startoffset
435 argument for pcre_exec() or pcre_dfa_exec()
436 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
437 or pcre_dfa_exec()
438 \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
439 or pcre_dfa_exec()
440 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
441 or pcre_dfa_exec()
442 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
443 or pcre_dfa_exec()
444 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
445 or pcre_dfa_exec()
446
447 Note that \xhh always specifies one byte, even in UTF-8 mode; this
448 makes it possible to construct invalid UTF-8 sequences for testing pur-
449 poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
450 UTF-8 mode, generating more than one byte if the value is greater than
451 127. When not in UTF-8 mode, it generates one byte for values less than
452 256, and causes an error for greater values.
453
454 The escapes that specify line ending sequences are literal strings,
455 exactly as shown. No more than one newline setting should be present in
456 any data line.
457
458 A backslash followed by anything else just escapes the anything else.
459 If the very last character is a backslash, it is ignored. This gives a
460 way of passing an empty line as data, since a real empty line termi-
461 nates the data input.
462
463 The \J escape provides a way of setting the maximum stack size that is
464 used by the just-in-time optimization code. It is ignored if JIT opti-
465 mization is not being used. Providing a stack that is larger than the
466 default 32K is necessary only for very complicated patterns.
467
468 If \M is present, pcretest calls pcre_exec() several times, with dif-
469 ferent values in the match_limit and match_limit_recursion fields of
470 the pcre_extra data structure, until it finds the minimum numbers for
471 each parameter that allow pcre_exec() to complete without error.
472 Because this is testing a specific feature of the normal interpretive
473 pcre_exec() execution, the use of any JIT optimization that might have
474 been set up by the /S+ qualifier of -s+ option is disabled.
475
476 The match_limit number is a measure of the amount of backtracking that
477 takes place, and checking it out can be instructive. For most simple
478 matches, the number is quite small, but for patterns with very large
479 numbers of matching possibilities, it can become large very quickly
480 with increasing length of subject string. The match_limit_recursion
481 number is a measure of how much stack (or, if PCRE is compiled with
482 NO_RECURSE, how much heap) memory is needed to complete the match
483 attempt.
484
485 When \O is used, the value specified may be higher or lower than the
486 size set by the -O command line option (or defaulted to 45); \O applies
487 only to the call of pcre_exec() for the line in which it appears.
488
489 If the /P modifier was present on the pattern, causing the POSIX wrap-
490 per API to be used, the only option-setting sequences that have any
491 effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
492 REG_NOTEOL, respectively, to be passed to regexec().
493
494 The use of \x{hh...} to represent UTF-8 characters is not dependent on
495 the use of the /8 modifier on the pattern. It is recognized always.
496 There may be any number of hexadecimal digits inside the braces. The
497 result is from one to six bytes, encoded according to the original
498 UTF-8 rules of RFC 2279. This allows for values in the range 0 to
499 0x7FFFFFFF. Note that not all of those are valid Unicode code points,
500 or indeed valid UTF-8 characters according to the later rules in RFC
501 3629.
502
503
504 THE ALTERNATIVE MATCHING FUNCTION
505
506 By default, pcretest uses the standard PCRE matching function,
507 pcre_exec() to match each data line. From release 6.0, PCRE supports an
508 alternative matching function, pcre_dfa_test(), which operates in a
509 different way, and has some restrictions. The differences between the
510 two functions are described in the pcrematching documentation.
511
512 If a data line contains the \D escape sequence, or if the command line
513 contains the -dfa option, the alternative matching function is called.
514 This function finds all possible matches at a given point. If, however,
515 the \F escape sequence is present in the data line, it stops after the
516 first match is found. This is always the shortest possible match.
517
518
519 DEFAULT OUTPUT FROM PCRETEST
520
521 This section describes the output when the normal matching function,
522 pcre_exec(), is being used.
523
524 When a match succeeds, pcretest outputs the list of captured substrings
525 that pcre_exec() returns, starting with number 0 for the string that
526 matched the whole pattern. Otherwise, it outputs "No match" when the
527 return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
528 tially matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
529 (Note that this is the entire substring that was inspected during the
530 partial match; it may include characters before the actual match start
531 if a lookbehind assertion, \K, \b, or \B was involved.) For any other
532 return, pcretest outputs the PCRE negative error number and a short
533 descriptive phrase. If the error is a failed UTF-8 string check, the
534 byte offset of the start of the failing character and the reason code
535 are also output, provided that the size of the output vector is at
536 least two. Here is an example of an interactive pcretest run.
537
538 $ pcretest
539 PCRE version 8.13 2011-04-30
540
541 re> /^abc(\d+)/
542 data> abc123
543 0: abc123
544 1: 123
545 data> xyz
546 No match
547
548 Unset capturing substrings that are not followed by one that is set are
549 not returned by pcre_exec(), and are not shown by pcretest. In the fol-
550 lowing example, there are two capturing substrings, but when the first
551 data line is matched, the second, unset substring is not shown. An
552 "internal" unset substring is shown as "<unset>", as for the second
553 data line.
554
555 re> /(a)|(b)/
556 data> a
557 0: a
558 1: a
559 data> b
560 0: b
561 1: <unset>
562 2: b
563
564 If the strings contain any non-printing characters, they are output as
565 \0x escapes, or as \x{...} escapes if the /8 modifier was present on
566 the pattern. See below for the definition of non-printing characters.
567 If the pattern has the /+ modifier, the output for substring 0 is fol-
568 lowed by the the rest of the subject string, identified by "0+" like
569 this:
570
571 re> /cat/+
572 data> cataract
573 0: cat
574 0+ aract
575
576 If the pattern has the /g or /G modifier, the results of successive
577 matching attempts are output in sequence, like this:
578
579 re> /\Bi(\w\w)/g
580 data> Mississippi
581 0: iss
582 1: ss
583 0: iss
584 1: ss
585 0: ipp
586 1: pp
587
588 "No match" is output only if the first match attempt fails. Here is an
589 example of a failure message (the offset 4 that is specified by \>4 is
590 past the end of the subject string):
591
592 re> /xyz/
593 data> xyz\>4
594 Error -24 (bad offset value)
595
596 If any of the sequences \C, \G, or \L are present in a data line that
597 is successfully matched, the substrings extracted by the convenience
598 functions are output with C, G, or L after the string number instead of
599 a colon. This is in addition to the normal full list. The string length
600 (that is, the return from the extraction function) is given in paren-
601 theses after each string for \C and \G.
602
603 Note that whereas patterns can be continued over several lines (a plain
604 ">" prompt is used for continuations), data lines may not. However new-
605 lines can be included in data by means of the \n escape (or \r, \r\n,
606 etc., depending on the newline sequence setting).
607
608
609 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
610
611 When the alternative matching function, pcre_dfa_exec(), is used (by
612 means of the \D escape sequence or the -dfa command line option), the
613 output consists of a list of all the matches that start at the first
614 point in the subject where there is at least one match. For example:
615
616 re> /(tang|tangerine|tan)/
617 data> yellow tangerine\D
618 0: tangerine
619 1: tang
620 2: tan
621
622 (Using the normal matching function on this data finds only "tang".)
623 The longest matching string is always given first (and numbered zero).
624 After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
625 lowed by the partially matching substring. (Note that this is the
626 entire substring that was inspected during the partial match; it may
627 include characters before the actual match start if a lookbehind asser-
628 tion, \K, \b, or \B was involved.)
629
630 If /g is present on the pattern, the search for further matches resumes
631 at the end of the longest match. For example:
632
633 re> /(tang|tangerine|tan)/g
634 data> yellow tangerine and tangy sultana\D
635 0: tangerine
636 1: tang
637 2: tan
638 0: tang
639 1: tan
640 0: tan
641
642 Since the matching function does not support substring capture, the
643 escape sequences that are concerned with captured substrings are not
644 relevant.
645
646
647 RESTARTING AFTER A PARTIAL MATCH
648
649 When the alternative matching function has given the PCRE_ERROR_PARTIAL
650 return, indicating that the subject partially matched the pattern, you
651 can restart the match with additional subject data by means of the \R
652 escape sequence. For example:
653
654 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
655 data> 23ja\P\D
656 Partial match: 23ja
657 data> n05\R\D
658 0: n05
659
660 For further information about partial matching, see the pcrepartial
661 documentation.
662
663
664 CALLOUTS
665
666 If the pattern contains any callout requests, pcretest's callout func-
667 tion is called during matching. This works with both matching func-
668 tions. By default, the called function displays the callout number, the
669 start and current positions in the text at the callout time, and the
670 next pattern item to be tested. For example, the output
671
672 --->pqrabcdef
673 0 ^ ^ \d
674
675 indicates that callout number 0 occurred for a match attempt starting
676 at the fourth character of the subject string, when the pointer was at
677 the seventh character of the data, and when the next pattern item was
678 \d. Just one circumflex is output if the start and current positions
679 are the same.
680
681 Callouts numbered 255 are assumed to be automatic callouts, inserted as
682 a result of the /C pattern modifier. In this case, instead of showing
683 the callout number, the offset in the pattern, preceded by a plus, is
684 output. For example:
685
686 re> /\d?[A-E]\*/C
687 data> E*
688 --->E*
689 +0 ^ \d?
690 +3 ^ [A-E]
691 +8 ^^ \*
692 +10 ^ ^
693 0: E*
694
695 If a pattern contains (*MARK) items, an additional line is output when-
696 ever a change of latest mark is passed to the callout function. For
697 example:
698
699 re> /a(*MARK:X)bc/C
700 data> abc
701 --->abc
702 +0 ^ a
703 +1 ^^ (*MARK:X)
704 +10 ^^ b
705 Latest Mark: X
706 +11 ^ ^ c
707 +12 ^ ^
708 0: abc
709
710 The mark changes between matching "a" and "b", but stays the same for
711 the rest of the match, so nothing more is output. If, as a result of
712 backtracking, the mark reverts to being unset, the text "<unset>" is
713 output.
714
715 The callout function in pcretest returns zero (carry on matching) by
716 default, but you can use a \C item in a data line (as described above)
717 to change this and other parameters of the callout.
718
719 Inserting callouts can be helpful when using pcretest to check compli-
720 cated regular expressions. For further information about callouts, see
721 the pcrecallout documentation.
722
723
724 NON-PRINTING CHARACTERS
725
726 When pcretest is outputting text in the compiled version of a pattern,
727 bytes other than 32-126 are always treated as non-printing characters
728 are are therefore shown as hex escapes.
729
730 When pcretest is outputting text that is a matched part of a subject
731 string, it behaves in the same way, unless a different locale has been
732 set for the pattern (using the /L modifier). In this case, the
733 isprint() function to distinguish printing and non-printing characters.
734
735
736 SAVING AND RELOADING COMPILED PATTERNS
737
738 The facilities described in this section are not available when the
739 POSIX interface to PCRE is being used, that is, when the /P pattern
740 modifier is specified.
741
742 When the POSIX interface is not in use, you can cause pcretest to write
743 a compiled pattern to a file, by following the modifiers with > and a
744 file name. For example:
745
746 /pattern/im >/some/file
747
748 See the pcreprecompile documentation for a discussion about saving and
749 re-using compiled patterns. Note that if the pattern was successfully
750 studied with JIT optimization, the JIT data cannot be saved.
751
752 The data that is written is binary. The first eight bytes are the
753 length of the compiled pattern data followed by the length of the
754 optional study data, each written as four bytes in big-endian order
755 (most significant byte first). If there is no study data (either the
756 pattern was not studied, or studying did not return any data), the sec-
757 ond length is zero. The lengths are followed by an exact copy of the
758 compiled pattern. If there is additional study data, this (excluding
759 any JIT data) follows immediately after the compiled pattern. After
760 writing the file, pcretest expects to read a new pattern.
761
762 A saved pattern can be reloaded into pcretest by specifying < and a
763 file name instead of a pattern. The name of the file must not contain a
764 < character, as otherwise pcretest will interpret the line as a pattern
765 delimited by < characters. For example:
766
767 re> </some/file
768 Compiled pattern loaded from /some/file
769 No study data
770
771 If the pattern was previously studied with the JIT optimization, the
772 JIT information cannot be saved and restored, and so is lost. When the
773 pattern has been loaded, pcretest proceeds to read data lines in the
774 usual way.
775
776 You can copy a file written by pcretest to a different host and reload
777 it there, even if the new host has opposite endianness to the one on
778 which the pattern was compiled. For example, you can compile on an i86
779 machine and run on a SPARC machine.
780
781 File names for saving and reloading can be absolute or relative, but
782 note that the shell facility of expanding a file name that starts with
783 a tilde (~) is not available.
784
785 The ability to save and reload files in pcretest is intended for test-
786 ing and experimentation. It is not intended for production use because
787 only a single pattern can be written to a file. Furthermore, there is
788 no facility for supplying custom character tables for use with a
789 reloaded pattern. If the original pattern was compiled with custom
790 tables, an attempt to match a subject string using a reloaded pattern
791 is likely to cause pcretest to crash. Finally, if you attempt to load
792 a file that is not in the correct format, the result is undefined.
793
794
795 SEE ALSO
796
797 pcre(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematching(3), pcrepar-
798 tial(d), pcrepattern(3), pcreprecompile(3).
799
800
801 AUTHOR
802
803 Philip Hazel
804 University Computing Service
805 Cambridge CB2 3QH, England.
806
807
808 REVISION
809
810 Last updated: 26 August 2011
811 Copyright (c) 1997-2011 University of Cambridge.

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