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5 pcretest - a program for testing Perl-compatible regular expressions.
10 pcretest [options] [input file [output file]]
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 and pcre16 documentation. The input for
18 pcretest is a sequence of regular expression patterns and strings to be
19 matched, as described below. The output shows the result of each match.
20 Options on the command line and the patterns control PCRE options and
21 exactly what is output.
26 From release 8.30, two separate PCRE libraries can be built. The origi-
27 nal one supports 8-bit character strings, whereas the newer 16-bit
28 library supports character strings encoded in 16-bit units. The
29 pcretest program can be used to test both libraries. However, it is
30 itself still an 8-bit program, reading 8-bit input and writing 8-bit
31 output. When testing the 16-bit library, the patterns and data strings
32 are converted to 16-bit format before being passed to the PCRE library
33 functions. Results are converted to 8-bit for output.
35 References to functions and structures of the form pcre[16]_xx below
36 mean "pcre_xx when using the 8-bit library or pcre16_xx when using the
37 16-bit library".
42 -16 If both the 8-bit and the 16-bit libraries have been built,
43 this option causes the 16-bit library to be used. If only the
44 16-bit library has been built, this is the default (so has no
45 effect). If only the 8-bit library has been built, this
46 option causes an error.
48 -b Behave as if each pattern has the /B (show byte code) modi-
49 fier; the internal form is output after compilation.
51 -C Output the version number of the PCRE library, and all avail-
52 able information about the optional features that are
53 included, and then exit. All other options are ignored.
55 -C option Output information about a specific build-time option, then
56 exit. This functionality is intended for use in scripts such
57 as RunTest. The following options output the value indicated:
59 linksize the internal link size (2, 3, or 4)
60 newline the default newline setting:
63 The following options output 1 for true or zero for false:
65 jit just-in-time support is available
66 pcre16 the 16-bit library was built
67 pcre8 the 8-bit library was built
68 ucp Unicode property support is available
69 utf UTF-8 and/or UTF-16 support is available
71 -d Behave as if each pattern has the /D (debug) modifier; the
72 internal form and information about the compiled pattern is
73 output after compilation; -d is equivalent to -b -i.
75 -dfa Behave as if each data line contains the \D escape sequence;
76 this causes the alternative matching function,
77 pcre[16]_dfa_exec(), to be used instead of the standard
78 pcre[16]_exec() function (more detail is given below).
80 -help Output a brief summary these options and then exit.
82 -i Behave as if each pattern has the /I modifier; information
83 about the compiled pattern is given after compilation.
85 -M Behave as if each data line contains the \M escape sequence;
86 this causes PCRE to discover the minimum MATCH_LIMIT and
87 MATCH_LIMIT_RECURSION settings by calling pcre[16]_exec()
88 repeatedly with different limits.
90 -m Output the size of each compiled pattern after it has been
91 compiled. This is equivalent to adding /M to each regular
92 expression. The size is given in bytes for both libraries.
94 -o osize Set the number of elements in the output vector that is used
95 when calling pcre[16]_exec() or pcre[16]_dfa_exec() to be
96 osize. The default value is 45, which is enough for 14 cap-
97 turing subexpressions for pcre[16]_exec() or 22 different
98 matches for pcre[16]_dfa_exec(). The vector size can be
99 changed for individual matching calls by including \O in the
100 data line (see below).
102 -p Behave as if each pattern has the /P modifier; the POSIX
103 wrapper API is used to call PCRE. None of the other options
104 has any effect when -p is set. This option can be used only
105 with the 8-bit library.
107 -q Do not output the version number of pcretest at the start of
108 execution.
110 -S size On Unix-like systems, set the size of the run-time stack to
111 size megabytes.
113 -s or -s+ Behave as if each pattern has the /S modifier; in other
114 words, force each pattern to be studied. If -s+ is used, the
115 PCRE_STUDY_JIT_COMPILE flag is passed to pcre[16]_study(),
116 causing just-in-time optimization to be set up if it is
117 available. If the /I or /D option is present on a pattern
118 (requesting output about the compiled pattern), information
119 about the result of studying is not included when studying is
120 caused only by -s and neither -i nor -d is present on the
121 command line. This behaviour means that the output from tests
122 that are run with and without -s should be identical, except
123 when options that output information about the actual running
124 of a match are set.
126 The -M, -t, and -tm options, which give information about
127 resources used, are likely to produce different output with
128 and without -s. Output may also differ if the /C option is
129 present on an individual pattern. This uses callouts to trace
130 the the matching process, and this may be different between
131 studied and non-studied patterns. If the pattern contains
132 (*MARK) items there may also be differences, for the same
133 reason. The -s command line option can be overridden for spe-
134 cific patterns that should never be studied (see the /S pat-
135 tern modifier below).
137 -t Run each compile, study, and match many times with a timer,
138 and output resulting time per compile or match (in millisec-
139 onds). Do not set -m with -t, because you will then get the
140 size output a zillion times, and the timing will be dis-
141 torted. You can control the number of iterations that are
142 used for timing by following -t with a number (as a separate
143 item on the command line). For example, "-t 1000" would iter-
144 ate 1000 times. The default is to iterate 500000 times.
146 -tm This is like -t except that it times only the matching phase,
147 not the compile or study phases.
152 If pcretest is given two filename arguments, it reads from the first
153 and writes to the second. If it is given only one filename argument, it
154 reads from that file and writes to stdout. Otherwise, it reads from
155 stdin and writes to stdout, and prompts for each line of input, using
156 "re>" to prompt for regular expressions, and "data>" to prompt for data
157 lines.
159 When pcretest is built, a configuration option can specify that it
160 should be linked with the libreadline library. When this is done, if
161 the input is from a terminal, it is read using the readline() function.
162 This provides line-editing and history facilities. The output from the
163 -help option states whether or not readline() will be used.
165 The program handles any number of sets of input on a single input file.
166 Each set starts with a regular expression, and continues with any num-
167 ber of data lines to be matched against the pattern.
169 Each data line is matched separately and independently. If you want to
170 do multi-line matches, you have to use the \n escape sequence (or \r or
171 \r\n, etc., depending on the newline setting) in a single line of input
172 to encode the newline sequences. There is no limit on the length of
173 data lines; the input buffer is automatically extended if it is too
174 small.
176 An empty line signals the end of the data lines, at which point a new
177 regular expression is read. The regular expressions are given enclosed
178 in any non-alphanumeric delimiters other than backslash, for example:
180 /(a|bc)x+yz/
182 White space before the initial delimiter is ignored. A regular expres-
183 sion may be continued over several input lines, in which case the new-
184 line characters are included within it. It is possible to include the
185 delimiter within the pattern by escaping it, for example
187 /abc\/def/
189 If you do so, the escape and the delimiter form part of the pattern,
190 but since delimiters are always non-alphanumeric, this does not affect
191 its interpretation. If the terminating delimiter is immediately fol-
192 lowed by a backslash, for example,
194 /abc/\
196 then a backslash is added to the end of the pattern. This is done to
197 provide a way of testing the error condition that arises if a pattern
198 finishes with a backslash, because
200 /abc\/
202 is interpreted as the first line of a pattern that starts with "abc/",
203 causing pcretest to read the next line as a continuation of the regular
204 expression.
209 A pattern may be followed by any number of modifiers, which are mostly
210 single characters. Following Perl usage, these are referred to below
211 as, for example, "the /i modifier", even though the delimiter of the
212 pattern need not always be a slash, and no slash is used when writing
213 modifiers. White space may appear between the final pattern delimiter
214 and the first modifier, and between the modifiers themselves.
216 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
217 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre[16]_com-
218 pile() is called. These four modifier letters have the same effect as
219 they do in Perl. For example:
221 /caseless/i
223 The following table shows additional modifiers for setting PCRE com-
224 pile-time options that do not correspond to anything in Perl:
226 /8 PCRE_UTF8 ) when using the 8-bit
227 /? PCRE_NO_UTF8_CHECK ) library
229 /8 PCRE_UTF16 ) when using the 16-bit
230 /? PCRE_NO_UTF16_CHECK ) library
248 /<bsr_anycrlf> PCRE_BSR_ANYCRLF
249 /<bsr_unicode> PCRE_BSR_UNICODE
251 The modifiers that are enclosed in angle brackets are literal strings
252 as shown, including the angle brackets, but the letters within can be
253 in either case. This example sets multiline matching with CRLF as the
254 line ending sequence:
256 /^abc/m<CRLF>
258 As well as turning on the PCRE_UTF8/16 option, the /8 modifier causes
259 all non-printing characters in output strings to be printed using the
260 \x{hh...} notation. Otherwise, those less than 0x100 are output in hex
261 without the curly brackets.
263 Full details of the PCRE options are given in the pcreapi documenta-
264 tion.
266 Finding all matches in a string
268 Searching for all possible matches within each subject string can be
269 requested by the /g or /G modifier. After finding a match, PCRE is
270 called again to search the remainder of the subject string. The differ-
271 ence between /g and /G is that the former uses the startoffset argument
272 to pcre[16]_exec() to start searching at a new point within the entire
273 string (which is in effect what Perl does), whereas the latter passes
274 over a shortened substring. This makes a difference to the matching
275 process if the pattern begins with a lookbehind assertion (including \b
276 or \B).
278 If any call to pcre[16]_exec() in a /g or /G sequence matches an empty
279 string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
280 PCRE_ANCHORED flags set in order to search for another, non-empty,
281 match at the same point. If this second match fails, the start offset
282 is advanced, and the normal match is retried. This imitates the way
283 Perl handles such cases when using the /g modifier or the split() func-
284 tion. Normally, the start offset is advanced by one character, but if
285 the newline convention recognizes CRLF as a newline, and the current
286 character is CR followed by LF, an advance of two is used.
288 Other modifiers
290 There are yet more modifiers for controlling the way pcretest operates.
292 The /+ modifier requests that as well as outputting the substring that
293 matched the entire pattern, pcretest should in addition output the
294 remainder of the subject string. This is useful for tests where the
295 subject contains multiple copies of the same substring. If the + modi-
296 fier appears twice, the same action is taken for captured substrings.
297 In each case the remainder is output on the following line with a plus
298 character following the capture number. Note that this modifier must
299 not immediately follow the /S modifier because /S+ has another meaning.
301 The /= modifier requests that the values of all potential captured
302 parentheses be output after a match. By default, only those up to the
303 highest one actually used in the match are output (corresponding to the
304 return code from pcre[16]_exec()). Values in the offsets vector corre-
305 sponding to higher numbers should be set to -1, and these are output as
306 "<unset>". This modifier gives a way of checking that this is happen-
307 ing.
309 The /B modifier is a debugging feature. It requests that pcretest out-
310 put a representation of the compiled code after compilation. Normally
311 this information contains length and offset values; however, if /Z is
312 also present, this data is replaced by spaces. This is a special fea-
313 ture for use in the automatic test scripts; it ensures that the same
314 output is generated for different internal link sizes.
316 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
317 that is, both the /B and the /I modifiers.
319 The /F modifier causes pcretest to flip the byte order of the 2-byte
320 and 4-byte fields in the compiled pattern. This facility is for testing
321 the feature in PCRE that allows it to execute patterns that were com-
322 piled on a host with a different endianness. This feature is not avail-
323 able when the POSIX interface to PCRE is being used, that is, when the
324 /P pattern modifier is specified. See also the section about saving and
325 reloading compiled patterns below.
327 The /I modifier requests that pcretest output information about the
328 compiled pattern (whether it is anchored, has a fixed first character,
329 and so on). It does this by calling pcre[16]_fullinfo() after compiling
330 a pattern. If the pattern is studied, the results of that are also out-
331 put.
333 The /K modifier requests pcretest to show names from backtracking con-
334 trol verbs that are returned from calls to pcre[16]_exec(). It causes
335 pcretest to create a pcre[16]_extra block if one has not already been
336 created by a call to pcre[16]_study(), and to set the PCRE_EXTRA_MARK
337 flag and the mark field within it, every time that pcre[16]_exec() is
338 called. If the variable that the mark field points to is non-NULL for a
339 match, non-match, or partial match, pcretest prints the string to which
340 it points. For a match, this is shown on a line by itself, tagged with
341 "MK:". For a non-match it is added to the message.
343 The /L modifier must be followed directly by the name of a locale, for
344 example,
346 /pattern/Lfr_FR
348 For this reason, it must be the last modifier. The given locale is set,
349 pcre[16]_maketables() is called to build a set of character tables for
350 the locale, and this is then passed to pcre[16]_compile() when compil-
351 ing the regular expression. Without an /L (or /T) modifier, NULL is
352 passed as the tables pointer; that is, /L applies only to the expres-
353 sion on which it appears.
355 The /M modifier causes the size in bytes of the memory block used to
356 hold the compiled pattern to be output. This does not include the size
357 of the pcre[16] block; it is just the actual compiled data. If the pat-
358 tern is successfully studied with the PCRE_STUDY_JIT_COMPILE option,
359 the size of the JIT compiled code is also output.
361 If the /S modifier appears once, it causes pcre[16]_study() to be
362 called after the expression has been compiled, and the results used
363 when the expression is matched. If /S appears twice, it suppresses
364 studying, even if it was requested externally by the -s command line
365 option. This makes it possible to specify that certain patterns are
366 always studied, and others are never studied, independently of -s. This
367 feature is used in the test files in a few cases where the output is
368 different when the pattern is studied.
370 If the /S modifier is immediately followed by a + character, the call
371 to pcre[16]_study() is made with the PCRE_STUDY_JIT_COMPILE option,
372 requesting just-in-time optimization support if it is available. Note
373 that there is also a /+ modifier; it must not be given immediately
374 after /S because this will be misinterpreted. If JIT studying is suc-
375 cessful, it will automatically be used when pcre[16]_exec() is run,
376 except when incompatible run-time options are specified. These include
377 the partial matching options; a complete list is given in the pcrejit
378 documentation. See also the \J escape sequence below for a way of set-
379 ting the size of the JIT stack.
381 The /T modifier must be followed by a single digit. It causes a spe-
382 cific set of built-in character tables to be passed to pcre[16]_com-
383 pile(). It is used in the standard PCRE tests to check behaviour with
384 different character tables. The digit specifies the tables as follows:
386 0 the default ASCII tables, as distributed in
387 pcre_chartables.c.dist
388 1 a set of tables defining ISO 8859 characters
390 In table 1, some characters whose codes are greater than 128 are iden-
391 tified as letters, digits, spaces, etc.
393 Using the POSIX wrapper API
395 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
396 rather than its native API. This supports only the 8-bit library. When
397 /P is set, the following modifiers set options for the regcomp() func-
398 tion:
400 /i REG_ICASE
403 /s REG_DOTALL )
404 /U REG_UNGREEDY ) These options are not part of
405 /W REG_UCP ) the POSIX standard
406 /8 REG_UTF8 )
408 The /+ modifier works as described above. All other modifiers are
409 ignored.
414 Before each data line is passed to pcre[16]_exec(), leading and trail-
415 ing white space is removed, and it is then scanned for \ escapes. Some
416 of these are pretty esoteric features, intended for checking out some
417 of the more complicated features of PCRE. If you are just testing
418 "ordinary" regular expressions, you probably don't need any of these.
419 The following escapes are recognized:
421 \a alarm (BEL, \x07)
422 \b backspace (\x08)
423 \e escape (\x27)
424 \f form feed (\x0c)
425 \n newline (\x0a)
426 \qdd set the PCRE_MATCH_LIMIT limit to dd
427 (any number of digits)
428 \r carriage return (\x0d)
429 \t tab (\x09)
430 \v vertical tab (\x0b)
431 \nnn octal character (up to 3 octal digits); always
432 a byte unless > 255 in UTF-8 or 16-bit mode
433 \xhh hexadecimal byte (up to 2 hex digits)
434 \x{hh...} hexadecimal character (any number of hex digits)
435 \A pass the PCRE_ANCHORED option to pcre[16]_exec()
436 or pcre[16]_dfa_exec()
437 \B pass the PCRE_NOTBOL option to pcre[16]_exec()
438 or pcre[16]_dfa_exec()
439 \Cdd call pcre[16]_copy_substring() for substring dd
440 after a successful match (number less than 32)
441 \Cname call pcre[16]_copy_named_substring() for substring
442 "name" after a successful match (name termin-
443 ated by next non alphanumeric character)
444 \C+ show the current captured substrings at callout
445 time
446 \C- do not supply a callout function
447 \C!n return 1 instead of 0 when callout number n is
448 reached
449 \C!n!m return 1 instead of 0 when callout number n is
450 reached for the nth time
451 \C*n pass the number n (may be negative) as callout
452 data; this is used as the callout return value
453 \D use the pcre[16]_dfa_exec() match function
454 \F only shortest match for pcre[16]_dfa_exec()
455 \Gdd call pcre[16]_get_substring() for substring dd
456 after a successful match (number less than 32)
457 \Gname call pcre[16]_get_named_substring() for substring
458 "name" after a successful match (name termin-
459 ated by next non-alphanumeric character)
460 \Jdd set up a JIT stack of dd kilobytes maximum (any
461 number of digits)
462 \L call pcre[16]_get_substringlist() after a
463 successful match
464 \M discover the minimum MATCH_LIMIT and
466 \N pass the PCRE_NOTEMPTY option to pcre[16]_exec()
467 or pcre[16]_dfa_exec(); if used twice, pass the
469 \Odd set the size of the output vector passed to
470 pcre[16]_exec() to dd (any number of digits)
471 \P pass the PCRE_PARTIAL_SOFT option to pcre[16]_exec()
472 or pcre[16]_dfa_exec(); if used twice, pass the
474 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
475 (any number of digits)
476 \R pass the PCRE_DFA_RESTART option to pcre[16]_dfa_exec()
477 \S output details of memory get/free calls during matching
478 \Y pass the PCRE_NO_START_OPTIMIZE option to pcre[16]_exec()
479 or pcre[16]_dfa_exec()
480 \Z pass the PCRE_NOTEOL option to pcre[16]_exec()
481 or pcre[16]_dfa_exec()
482 \? pass the PCRE_NO_UTF[8|16]_CHECK option to
483 pcre[16]_exec() or pcre[16]_dfa_exec()
484 \>dd start the match at offset dd (optional "-"; then
485 any number of digits); this sets the startoffset
486 argument for pcre[16]_exec() or pcre[16]_dfa_exec()
487 \<cr> pass the PCRE_NEWLINE_CR option to pcre[16]_exec()
488 or pcre[16]_dfa_exec()
489 \<lf> pass the PCRE_NEWLINE_LF option to pcre[16]_exec()
490 or pcre[16]_dfa_exec()
491 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre[16]_exec()
492 or pcre[16]_dfa_exec()
493 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre[16]_exec()
494 or pcre[16]_dfa_exec()
495 \<any> pass the PCRE_NEWLINE_ANY option to pcre[16]_exec()
496 or pcre[16]_dfa_exec()
498 The use of \x{hh...} is not dependent on the use of the /8 modifier on
499 the pattern. It is recognized always. There may be any number of hexa-
500 decimal digits inside the braces; invalid values provoke error mes-
501 sages.
503 Note that \xhh specifies one byte rather than one character in UTF-8
504 mode; this makes it possible to construct invalid UTF-8 sequences for
505 testing purposes. On the other hand, \x{hh} is interpreted as a UTF-8
506 character in UTF-8 mode, generating more than one byte if the value is
507 greater than 127. When testing the 8-bit library not in UTF-8 mode,
508 \x{hh} generates one byte for values less than 256, and causes an error
509 for greater values.
511 In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
512 possible to construct invalid UTF-16 sequences for testing purposes.
514 The escapes that specify line ending sequences are literal strings,
515 exactly as shown. No more than one newline setting should be present in
516 any data line.
518 A backslash followed by anything else just escapes the anything else.
519 If the very last character is a backslash, it is ignored. This gives a
520 way of passing an empty line as data, since a real empty line termi-
521 nates the data input.
523 The \J escape provides a way of setting the maximum stack size that is
524 used by the just-in-time optimization code. It is ignored if JIT opti-
525 mization is not being used. Providing a stack that is larger than the
526 default 32K is necessary only for very complicated patterns.
528 If \M is present, pcretest calls pcre[16]_exec() several times, with
529 different values in the match_limit and match_limit_recursion fields of
530 the pcre[16]_extra data structure, until it finds the minimum numbers
531 for each parameter that allow pcre[16]_exec() to complete without
532 error. Because this is testing a specific feature of the normal inter-
533 pretive pcre[16]_exec() execution, the use of any JIT optimization that
534 might have been set up by the /S+ qualifier of -s+ option is disabled.
536 The match_limit number is a measure of the amount of backtracking that
537 takes place, and checking it out can be instructive. For most simple
538 matches, the number is quite small, but for patterns with very large
539 numbers of matching possibilities, it can become large very quickly
540 with increasing length of subject string. The match_limit_recursion
541 number is a measure of how much stack (or, if PCRE is compiled with
542 NO_RECURSE, how much heap) memory is needed to complete the match
543 attempt.
545 When \O is used, the value specified may be higher or lower than the
546 size set by the -O command line option (or defaulted to 45); \O applies
547 only to the call of pcre[16]_exec() for the line in which it appears.
549 If the /P modifier was present on the pattern, causing the POSIX wrap-
550 per API to be used, the only option-setting sequences that have any
551 effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
552 REG_NOTEOL, respectively, to be passed to regexec().
557 By default, pcretest uses the standard PCRE matching function,
558 pcre[16]_exec() to match each data line. PCRE also supports an alterna-
559 tive matching function, pcre[16]_dfa_test(), which operates in a dif-
560 ferent way, and has some restrictions. The differences between the two
561 functions are described in the pcrematching documentation.
563 If a data line contains the \D escape sequence, or if the command line
564 contains the -dfa option, the alternative matching function is used.
565 This function finds all possible matches at a given point. If, however,
566 the \F escape sequence is present in the data line, it stops after the
567 first match is found. This is always the shortest possible match.
572 This section describes the output when the normal matching function,
573 pcre[16]_exec(), is being used.
575 When a match succeeds, pcretest outputs the list of captured substrings
576 that pcre[16]_exec() returns, starting with number 0 for the string
577 that matched the whole pattern. Otherwise, it outputs "No match" when
578 the return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the
579 partially matching substring when pcre[16]_exec() returns
580 PCRE_ERROR_PARTIAL. (Note that this is the entire substring that was
581 inspected during the partial match; it may include characters before
582 the actual match start if a lookbehind assertion, \K, \b, or \B was
583 involved.) For any other return, pcretest outputs the PCRE negative
584 error number and a short descriptive phrase. If the error is a failed
585 UTF string check, the offset of the start of the failing character and
586 the reason code are also output, provided that the size of the output
587 vector is at least two. Here is an example of an interactive pcretest
588 run.
590 $ pcretest
591 PCRE version 8.13 2011-04-30
593 re> /^abc(\d+)/
594 data> abc123
595 0: abc123
596 1: 123
597 data> xyz
598 No match
600 Unset capturing substrings that are not followed by one that is set are
601 not returned by pcre[16]_exec(), and are not shown by pcretest. In the
602 following example, there are two capturing substrings, but when the
603 first data line is matched, the second, unset substring is not shown.
604 An "internal" unset substring is shown as "<unset>", as for the second
605 data line.
607 re> /(a)|(b)/
608 data> a
609 0: a
610 1: a
611 data> b
612 0: b
613 1: <unset>
614 2: b
616 If the strings contain any non-printing characters, they are output as
617 \xhh escapes if the value is less than 256 and UTF mode is not set.
618 Otherwise they are output as \x{hh...} escapes. See below for the defi-
619 nition of non-printing characters. If the pattern has the /+ modifier,
620 the output for substring 0 is followed by the the rest of the subject
621 string, identified by "0+" like this:
623 re> /cat/+
624 data> cataract
625 0: cat
626 0+ aract
628 If the pattern has the /g or /G modifier, the results of successive
629 matching attempts are output in sequence, like this:
631 re> /\Bi(\w\w)/g
632 data> Mississippi
633 0: iss
634 1: ss
635 0: iss
636 1: ss
637 0: ipp
638 1: pp
640 "No match" is output only if the first match attempt fails. Here is an
641 example of a failure message (the offset 4 that is specified by \>4 is
642 past the end of the subject string):
644 re> /xyz/
645 data> xyz\>4
646 Error -24 (bad offset value)
648 If any of the sequences \C, \G, or \L are present in a data line that
649 is successfully matched, the substrings extracted by the convenience
650 functions are output with C, G, or L after the string number instead of
651 a colon. This is in addition to the normal full list. The string length
652 (that is, the return from the extraction function) is given in paren-
653 theses after each string for \C and \G.
655 Note that whereas patterns can be continued over several lines (a plain
656 ">" prompt is used for continuations), data lines may not. However new-
657 lines can be included in data by means of the \n escape (or \r, \r\n,
658 etc., depending on the newline sequence setting).
663 When the alternative matching function, pcre[16]_dfa_exec(), is used
664 (by means of the \D escape sequence or the -dfa command line option),
665 the output consists of a list of all the matches that start at the
666 first point in the subject where there is at least one match. For exam-
667 ple:
669 re> /(tang|tangerine|tan)/
670 data> yellow tangerine\D
671 0: tangerine
672 1: tang
673 2: tan
675 (Using the normal matching function on this data finds only "tang".)
676 The longest matching string is always given first (and numbered zero).
677 After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
678 lowed by the partially matching substring. (Note that this is the
679 entire substring that was inspected during the partial match; it may
680 include characters before the actual match start if a lookbehind asser-
681 tion, \K, \b, or \B was involved.)
683 If /g is present on the pattern, the search for further matches resumes
684 at the end of the longest match. For example:
686 re> /(tang|tangerine|tan)/g
687 data> yellow tangerine and tangy sultana\D
688 0: tangerine
689 1: tang
690 2: tan
691 0: tang
692 1: tan
693 0: tan
695 Since the matching function does not support substring capture, the
696 escape sequences that are concerned with captured substrings are not
697 relevant.
702 When the alternative matching function has given the PCRE_ERROR_PARTIAL
703 return, indicating that the subject partially matched the pattern, you
704 can restart the match with additional subject data by means of the \R
705 escape sequence. For example:
707 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
708 data> 23ja\P\D
709 Partial match: 23ja
710 data> n05\R\D
711 0: n05
713 For further information about partial matching, see the pcrepartial
714 documentation.
719 If the pattern contains any callout requests, pcretest's callout func-
720 tion is called during matching. This works with both matching func-
721 tions. By default, the called function displays the callout number, the
722 start and current positions in the text at the callout time, and the
723 next pattern item to be tested. For example:
725 --->pqrabcdef
726 0 ^ ^ \d
728 This output indicates that callout number 0 occurred for a match
729 attempt starting at the fourth character of the subject string, when
730 the pointer was at the seventh character of the data, and when the next
731 pattern item was \d. Just one circumflex is output if the start and
732 current positions are the same.
734 Callouts numbered 255 are assumed to be automatic callouts, inserted as
735 a result of the /C pattern modifier. In this case, instead of showing
736 the callout number, the offset in the pattern, preceded by a plus, is
737 output. For example:
739 re> /\d?[A-E]\*/C
740 data> E*
741 --->E*
742 +0 ^ \d?
743 +3 ^ [A-E]
744 +8 ^^ \*
745 +10 ^ ^
746 0: E*
748 If a pattern contains (*MARK) items, an additional line is output when-
749 ever a change of latest mark is passed to the callout function. For
750 example:
752 re> /a(*MARK:X)bc/C
753 data> abc
754 --->abc
755 +0 ^ a
756 +1 ^^ (*MARK:X)
757 +10 ^^ b
758 Latest Mark: X
759 +11 ^ ^ c
760 +12 ^ ^
761 0: abc
763 The mark changes between matching "a" and "b", but stays the same for
764 the rest of the match, so nothing more is output. If, as a result of
765 backtracking, the mark reverts to being unset, the text "<unset>" is
766 output.
768 The callout function in pcretest returns zero (carry on matching) by
769 default, but you can use a \C item in a data line (as described above)
770 to change this and other parameters of the callout.
772 Inserting callouts can be helpful when using pcretest to check compli-
773 cated regular expressions. For further information about callouts, see
774 the pcrecallout documentation.
779 When pcretest is outputting text in the compiled version of a pattern,
780 bytes other than 32-126 are always treated as non-printing characters
781 are are therefore shown as hex escapes.
783 When pcretest is outputting text that is a matched part of a subject
784 string, it behaves in the same way, unless a different locale has been
785 set for the pattern (using the /L modifier). In this case, the
786 isprint() function to distinguish printing and non-printing characters.
791 The facilities described in this section are not available when the
792 POSIX interface to PCRE is being used, that is, when the /P pattern
793 modifier is specified.
795 When the POSIX interface is not in use, you can cause pcretest to write
796 a compiled pattern to a file, by following the modifiers with > and a
797 file name. For example:
799 /pattern/im >/some/file
801 See the pcreprecompile documentation for a discussion about saving and
802 re-using compiled patterns. Note that if the pattern was successfully
803 studied with JIT optimization, the JIT data cannot be saved.
805 The data that is written is binary. The first eight bytes are the
806 length of the compiled pattern data followed by the length of the
807 optional study data, each written as four bytes in big-endian order
808 (most significant byte first). If there is no study data (either the
809 pattern was not studied, or studying did not return any data), the sec-
810 ond length is zero. The lengths are followed by an exact copy of the
811 compiled pattern. If there is additional study data, this (excluding
812 any JIT data) follows immediately after the compiled pattern. After
813 writing the file, pcretest expects to read a new pattern.
815 A saved pattern can be reloaded into pcretest by specifying < and a
816 file name instead of a pattern. The name of the file must not contain a
817 < character, as otherwise pcretest will interpret the line as a pattern
818 delimited by < characters. For example:
820 re> </some/file
821 Compiled pattern loaded from /some/file
822 No study data
824 If the pattern was previously studied with the JIT optimization, the
825 JIT information cannot be saved and restored, and so is lost. When the
826 pattern has been loaded, pcretest proceeds to read data lines in the
827 usual way.
829 You can copy a file written by pcretest to a different host and reload
830 it there, even if the new host has opposite endianness to the one on
831 which the pattern was compiled. For example, you can compile on an i86
832 machine and run on a SPARC machine. When a pattern is reloaded on a
833 host with different endianness, the confirmation message is changed to:
835 Compiled pattern (byte-inverted) loaded from /some/file
837 The test suite contains some saved pre-compiled patterns with different
838 endianness. These are reloaded using "<!" instead of just "<". This
839 suppresses the "(byte-inverted)" text so that the output is the same on
840 all hosts. It also forces debugging output once the pattern has been
841 reloaded.
843 File names for saving and reloading can be absolute or relative, but
844 note that the shell facility of expanding a file name that starts with
845 a tilde (~) is not available.
847 The ability to save and reload files in pcretest is intended for test-
848 ing and experimentation. It is not intended for production use because
849 only a single pattern can be written to a file. Furthermore, there is
850 no facility for supplying custom character tables for use with a
851 reloaded pattern. If the original pattern was compiled with custom
852 tables, an attempt to match a subject string using a reloaded pattern
853 is likely to cause pcretest to crash. Finally, if you attempt to load
854 a file that is not in the correct format, the result is undefined.
859 pcre(3), pcre16(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematch-
860 ing(3), pcrepartial(d), pcrepattern(3), pcreprecompile(3).
865 Philip Hazel
866 University Computing Service
867 Cambridge CB2 3QH, England.
872 Last updated: 14 January 2012
873 Copyright (c) 1997-2012 University of Cambridge.


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