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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, all
115 the JIT compile options are passed to pcre[16]_study(), caus-
116 ing just-in-time optimization to be set up if it is avail-
117 able, for both full and partial matching. Specific JIT com-
118 pile options can be selected by following -s+ with a digit in
119 the range 1 to 7, which selects the JIT compile modes as fol-
120 lows:
122 1 normal match only
123 2 soft partial match only
124 3 normal match and soft partial match
125 4 hard partial match only
126 6 soft and hard partial match
127 7 all three modes (default)
129 If -s++ is used instead of -s+ (with or without a following
130 digit), the text "(JIT)" is added to the first output line
131 after a match or no match when JIT-compiled code was actually
132 used.
134 If the /I or /D option is present on a pattern (requesting output about
135 the compiled pattern), information about the result of studying is not
136 included when studying is caused only by -s and neither -i nor -d is
137 present on the command line. This behaviour means that the output from
138 tests that are run with and without -s should be identical, except when
139 options that output information about the actual running of a match are
140 set.
142 The -M, -t, and -tm options, which give information about resources
143 used, are likely to produce different output with and without -s. Out-
144 put may also differ if the /C option is present on an individual pat-
145 tern. This uses callouts to trace the the matching process, and this
146 may be different between studied and non-studied patterns. If the pat-
147 tern contains (*MARK) items there may also be differences, for the same
148 reason. The -s command line option can be overridden for specific pat-
149 terns that should never be studied (see the /S pattern modifier below).
151 -t Run each compile, study, and match many times with a timer,
152 and output resulting time per compile or match (in millisec-
153 onds). Do not set -m with -t, because you will then get the
154 size output a zillion times, and the timing will be dis-
155 torted. You can control the number of iterations that are
156 used for timing by following -t with a number (as a separate
157 item on the command line). For example, "-t 1000" would iter-
158 ate 1000 times. The default is to iterate 500000 times.
160 -tm This is like -t except that it times only the matching phase,
161 not the compile or study phases.
166 If pcretest is given two filename arguments, it reads from the first
167 and writes to the second. If it is given only one filename argument, it
168 reads from that file and writes to stdout. Otherwise, it reads from
169 stdin and writes to stdout, and prompts for each line of input, using
170 "re>" to prompt for regular expressions, and "data>" to prompt for data
171 lines.
173 When pcretest is built, a configuration option can specify that it
174 should be linked with the libreadline library. When this is done, if
175 the input is from a terminal, it is read using the readline() function.
176 This provides line-editing and history facilities. The output from the
177 -help option states whether or not readline() will be used.
179 The program handles any number of sets of input on a single input file.
180 Each set starts with a regular expression, and continues with any num-
181 ber of data lines to be matched against the pattern.
183 Each data line is matched separately and independently. If you want to
184 do multi-line matches, you have to use the \n escape sequence (or \r or
185 \r\n, etc., depending on the newline setting) in a single line of input
186 to encode the newline sequences. There is no limit on the length of
187 data lines; the input buffer is automatically extended if it is too
188 small.
190 An empty line signals the end of the data lines, at which point a new
191 regular expression is read. The regular expressions are given enclosed
192 in any non-alphanumeric delimiters other than backslash, for example:
194 /(a|bc)x+yz/
196 White space before the initial delimiter is ignored. A regular expres-
197 sion may be continued over several input lines, in which case the new-
198 line characters are included within it. It is possible to include the
199 delimiter within the pattern by escaping it, for example
201 /abc\/def/
203 If you do so, the escape and the delimiter form part of the pattern,
204 but since delimiters are always non-alphanumeric, this does not affect
205 its interpretation. If the terminating delimiter is immediately fol-
206 lowed by a backslash, for example,
208 /abc/\
210 then a backslash is added to the end of the pattern. This is done to
211 provide a way of testing the error condition that arises if a pattern
212 finishes with a backslash, because
214 /abc\/
216 is interpreted as the first line of a pattern that starts with "abc/",
217 causing pcretest to read the next line as a continuation of the regular
218 expression.
223 A pattern may be followed by any number of modifiers, which are mostly
224 single characters. Following Perl usage, these are referred to below
225 as, for example, "the /i modifier", even though the delimiter of the
226 pattern need not always be a slash, and no slash is used when writing
227 modifiers. White space may appear between the final pattern delimiter
228 and the first modifier, and between the modifiers themselves.
230 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
231 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre[16]_com-
232 pile() is called. These four modifier letters have the same effect as
233 they do in Perl. For example:
235 /caseless/i
237 The following table shows additional modifiers for setting PCRE com-
238 pile-time options that do not correspond to anything in Perl:
240 /8 PCRE_UTF8 ) when using the 8-bit
241 /? PCRE_NO_UTF8_CHECK ) library
243 /8 PCRE_UTF16 ) when using the 16-bit
244 /? PCRE_NO_UTF16_CHECK ) library
262 /<bsr_anycrlf> PCRE_BSR_ANYCRLF
263 /<bsr_unicode> PCRE_BSR_UNICODE
265 The modifiers that are enclosed in angle brackets are literal strings
266 as shown, including the angle brackets, but the letters within can be
267 in either case. This example sets multiline matching with CRLF as the
268 line ending sequence:
270 /^abc/m<CRLF>
272 As well as turning on the PCRE_UTF8/16 option, the /8 modifier causes
273 all non-printing characters in output strings to be printed using the
274 \x{hh...} notation. Otherwise, those less than 0x100 are output in hex
275 without the curly brackets.
277 Full details of the PCRE options are given in the pcreapi documenta-
278 tion.
280 Finding all matches in a string
282 Searching for all possible matches within each subject string can be
283 requested by the /g or /G modifier. After finding a match, PCRE is
284 called again to search the remainder of the subject string. The differ-
285 ence between /g and /G is that the former uses the startoffset argument
286 to pcre[16]_exec() to start searching at a new point within the entire
287 string (which is in effect what Perl does), whereas the latter passes
288 over a shortened substring. This makes a difference to the matching
289 process if the pattern begins with a lookbehind assertion (including \b
290 or \B).
292 If any call to pcre[16]_exec() in a /g or /G sequence matches an empty
293 string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
294 PCRE_ANCHORED flags set in order to search for another, non-empty,
295 match at the same point. If this second match fails, the start offset
296 is advanced, and the normal match is retried. This imitates the way
297 Perl handles such cases when using the /g modifier or the split() func-
298 tion. Normally, the start offset is advanced by one character, but if
299 the newline convention recognizes CRLF as a newline, and the current
300 character is CR followed by LF, an advance of two is used.
302 Other modifiers
304 There are yet more modifiers for controlling the way pcretest operates.
306 The /+ modifier requests that as well as outputting the substring that
307 matched the entire pattern, pcretest should in addition output the
308 remainder of the subject string. This is useful for tests where the
309 subject contains multiple copies of the same substring. If the + modi-
310 fier appears twice, the same action is taken for captured substrings.
311 In each case the remainder is output on the following line with a plus
312 character following the capture number. Note that this modifier must
313 not immediately follow the /S modifier because /S+ and /S++ have other
314 meanings.
316 The /= modifier requests that the values of all potential captured
317 parentheses be output after a match. By default, only those up to the
318 highest one actually used in the match are output (corresponding to the
319 return code from pcre[16]_exec()). Values in the offsets vector corre-
320 sponding to higher numbers should be set to -1, and these are output as
321 "<unset>". This modifier gives a way of checking that this is happen-
322 ing.
324 The /B modifier is a debugging feature. It requests that pcretest out-
325 put a representation of the compiled code after compilation. Normally
326 this information contains length and offset values; however, if /Z is
327 also present, this data is replaced by spaces. This is a special fea-
328 ture for use in the automatic test scripts; it ensures that the same
329 output is generated for different internal link sizes.
331 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
332 that is, both the /B and the /I modifiers.
334 The /F modifier causes pcretest to flip the byte order of the 2-byte
335 and 4-byte fields in the compiled pattern. This facility is for testing
336 the feature in PCRE that allows it to execute patterns that were com-
337 piled on a host with a different endianness. This feature is not avail-
338 able when the POSIX interface to PCRE is being used, that is, when the
339 /P pattern modifier is specified. See also the section about saving and
340 reloading compiled patterns below.
342 The /I modifier requests that pcretest output information about the
343 compiled pattern (whether it is anchored, has a fixed first character,
344 and so on). It does this by calling pcre[16]_fullinfo() after compiling
345 a pattern. If the pattern is studied, the results of that are also out-
346 put.
348 The /K modifier requests pcretest to show names from backtracking con-
349 trol verbs that are returned from calls to pcre[16]_exec(). It causes
350 pcretest to create a pcre[16]_extra block if one has not already been
351 created by a call to pcre[16]_study(), and to set the PCRE_EXTRA_MARK
352 flag and the mark field within it, every time that pcre[16]_exec() is
353 called. If the variable that the mark field points to is non-NULL for a
354 match, non-match, or partial match, pcretest prints the string to which
355 it points. For a match, this is shown on a line by itself, tagged with
356 "MK:". For a non-match it is added to the message.
358 The /L modifier must be followed directly by the name of a locale, for
359 example,
361 /pattern/Lfr_FR
363 For this reason, it must be the last modifier. The given locale is set,
364 pcre[16]_maketables() is called to build a set of character tables for
365 the locale, and this is then passed to pcre[16]_compile() when compil-
366 ing the regular expression. Without an /L (or /T) modifier, NULL is
367 passed as the tables pointer; that is, /L applies only to the expres-
368 sion on which it appears.
370 The /M modifier causes the size in bytes of the memory block used to
371 hold the compiled pattern to be output. This does not include the size
372 of the pcre[16] block; it is just the actual compiled data. If the pat-
373 tern is successfully studied with the PCRE_STUDY_JIT_COMPILE option,
374 the size of the JIT compiled code is also output.
376 If the /S modifier appears once, it causes pcre[16]_study() to be
377 called after the expression has been compiled, and the results used
378 when the expression is matched. If /S appears twice, it suppresses
379 studying, even if it was requested externally by the -s command line
380 option. This makes it possible to specify that certain patterns are
381 always studied, and others are never studied, independently of -s. This
382 feature is used in the test files in a few cases where the output is
383 different when the pattern is studied.
385 If the /S modifier is immediately followed by a + character, the call
386 to pcre[16]_study() is made with all the JIT study options, requesting
387 just-in-time optimization support if it is available, for both normal
388 and partial matching. If you want to restrict the JIT compiling modes,
389 you can follow /S+ with a digit in the range 1 to 7:
391 1 normal match only
392 2 soft partial match only
393 3 normal match and soft partial match
394 4 hard partial match only
395 6 soft and hard partial match
396 7 all three modes (default)
398 If /S++ is used instead of /S+ (with or without a following digit), the
399 text "(JIT)" is added to the first output line after a match or no
400 match when JIT-compiled code was actually used.
402 Note that there is also an independent /+ modifier; it must not be
403 given immediately after /S or /S+ because this will be misinterpreted.
405 If JIT studying is successful, the compiled JIT code will automatically
406 be used when pcre[16]_exec() is run, except when incompatible run-time
407 options are specified. For more details, see the pcrejit documentation.
408 See also the \J escape sequence below for a way of setting the size of
409 the JIT stack.
411 The /T modifier must be followed by a single digit. It causes a spe-
412 cific set of built-in character tables to be passed to pcre[16]_com-
413 pile(). It is used in the standard PCRE tests to check behaviour with
414 different character tables. The digit specifies the tables as follows:
416 0 the default ASCII tables, as distributed in
417 pcre_chartables.c.dist
418 1 a set of tables defining ISO 8859 characters
420 In table 1, some characters whose codes are greater than 128 are iden-
421 tified as letters, digits, spaces, etc.
423 Using the POSIX wrapper API
425 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
426 rather than its native API. This supports only the 8-bit library. When
427 /P is set, the following modifiers set options for the regcomp() func-
428 tion:
430 /i REG_ICASE
433 /s REG_DOTALL )
434 /U REG_UNGREEDY ) These options are not part of
435 /W REG_UCP ) the POSIX standard
436 /8 REG_UTF8 )
438 The /+ modifier works as described above. All other modifiers are
439 ignored.
444 Before each data line is passed to pcre[16]_exec(), leading and trail-
445 ing white space is removed, and it is then scanned for \ escapes. Some
446 of these are pretty esoteric features, intended for checking out some
447 of the more complicated features of PCRE. If you are just testing
448 "ordinary" regular expressions, you probably don't need any of these.
449 The following escapes are recognized:
451 \a alarm (BEL, \x07)
452 \b backspace (\x08)
453 \e escape (\x27)
454 \f form feed (\x0c)
455 \n newline (\x0a)
456 \qdd set the PCRE_MATCH_LIMIT limit to dd
457 (any number of digits)
458 \r carriage return (\x0d)
459 \t tab (\x09)
460 \v vertical tab (\x0b)
461 \nnn octal character (up to 3 octal digits); always
462 a byte unless > 255 in UTF-8 or 16-bit mode
463 \xhh hexadecimal byte (up to 2 hex digits)
464 \x{hh...} hexadecimal character (any number of hex digits)
465 \A pass the PCRE_ANCHORED option to pcre[16]_exec()
466 or pcre[16]_dfa_exec()
467 \B pass the PCRE_NOTBOL option to pcre[16]_exec()
468 or pcre[16]_dfa_exec()
469 \Cdd call pcre[16]_copy_substring() for substring dd
470 after a successful match (number less than 32)
471 \Cname call pcre[16]_copy_named_substring() for substring
472 "name" after a successful match (name termin-
473 ated by next non alphanumeric character)
474 \C+ show the current captured substrings at callout
475 time
476 \C- do not supply a callout function
477 \C!n return 1 instead of 0 when callout number n is
478 reached
479 \C!n!m return 1 instead of 0 when callout number n is
480 reached for the nth time
481 \C*n pass the number n (may be negative) as callout
482 data; this is used as the callout return value
483 \D use the pcre[16]_dfa_exec() match function
484 \F only shortest match for pcre[16]_dfa_exec()
485 \Gdd call pcre[16]_get_substring() for substring dd
486 after a successful match (number less than 32)
487 \Gname call pcre[16]_get_named_substring() for substring
488 "name" after a successful match (name termin-
489 ated by next non-alphanumeric character)
490 \Jdd set up a JIT stack of dd kilobytes maximum (any
491 number of digits)
492 \L call pcre[16]_get_substringlist() after a
493 successful match
494 \M discover the minimum MATCH_LIMIT and
496 \N pass the PCRE_NOTEMPTY option to pcre[16]_exec()
497 or pcre[16]_dfa_exec(); if used twice, pass the
499 \Odd set the size of the output vector passed to
500 pcre[16]_exec() to dd (any number of digits)
501 \P pass the PCRE_PARTIAL_SOFT option to pcre[16]_exec()
502 or pcre[16]_dfa_exec(); if used twice, pass the
504 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
505 (any number of digits)
506 \R pass the PCRE_DFA_RESTART option to pcre[16]_dfa_exec()
507 \S output details of memory get/free calls during matching
508 \Y pass the PCRE_NO_START_OPTIMIZE option to pcre[16]_exec()
509 or pcre[16]_dfa_exec()
510 \Z pass the PCRE_NOTEOL option to pcre[16]_exec()
511 or pcre[16]_dfa_exec()
512 \? pass the PCRE_NO_UTF[8|16]_CHECK option to
513 pcre[16]_exec() or pcre[16]_dfa_exec()
514 \>dd start the match at offset dd (optional "-"; then
515 any number of digits); this sets the startoffset
516 argument for pcre[16]_exec() or pcre[16]_dfa_exec()
517 \<cr> pass the PCRE_NEWLINE_CR option to pcre[16]_exec()
518 or pcre[16]_dfa_exec()
519 \<lf> pass the PCRE_NEWLINE_LF option to pcre[16]_exec()
520 or pcre[16]_dfa_exec()
521 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre[16]_exec()
522 or pcre[16]_dfa_exec()
523 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre[16]_exec()
524 or pcre[16]_dfa_exec()
525 \<any> pass the PCRE_NEWLINE_ANY option to pcre[16]_exec()
526 or pcre[16]_dfa_exec()
528 The use of \x{hh...} is not dependent on the use of the /8 modifier on
529 the pattern. It is recognized always. There may be any number of hexa-
530 decimal digits inside the braces; invalid values provoke error mes-
531 sages.
533 Note that \xhh specifies one byte rather than one character in UTF-8
534 mode; this makes it possible to construct invalid UTF-8 sequences for
535 testing purposes. On the other hand, \x{hh} is interpreted as a UTF-8
536 character in UTF-8 mode, generating more than one byte if the value is
537 greater than 127. When testing the 8-bit library not in UTF-8 mode,
538 \x{hh} generates one byte for values less than 256, and causes an error
539 for greater values.
541 In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
542 possible to construct invalid UTF-16 sequences for testing purposes.
544 The escapes that specify line ending sequences are literal strings,
545 exactly as shown. No more than one newline setting should be present in
546 any data line.
548 A backslash followed by anything else just escapes the anything else.
549 If the very last character is a backslash, it is ignored. This gives a
550 way of passing an empty line as data, since a real empty line termi-
551 nates the data input.
553 The \J escape provides a way of setting the maximum stack size that is
554 used by the just-in-time optimization code. It is ignored if JIT opti-
555 mization is not being used. Providing a stack that is larger than the
556 default 32K is necessary only for very complicated patterns.
558 If \M is present, pcretest calls pcre[16]_exec() several times, with
559 different values in the match_limit and match_limit_recursion fields of
560 the pcre[16]_extra data structure, until it finds the minimum numbers
561 for each parameter that allow pcre[16]_exec() to complete without
562 error. Because this is testing a specific feature of the normal inter-
563 pretive pcre[16]_exec() execution, the use of any JIT optimization that
564 might have been set up by the /S+ qualifier of -s+ option is disabled.
566 The match_limit number is a measure of the amount of backtracking that
567 takes place, and checking it out can be instructive. For most simple
568 matches, the number is quite small, but for patterns with very large
569 numbers of matching possibilities, it can become large very quickly
570 with increasing length of subject string. The match_limit_recursion
571 number is a measure of how much stack (or, if PCRE is compiled with
572 NO_RECURSE, how much heap) memory is needed to complete the match
573 attempt.
575 When \O is used, the value specified may be higher or lower than the
576 size set by the -O command line option (or defaulted to 45); \O applies
577 only to the call of pcre[16]_exec() for the line in which it appears.
579 If the /P modifier was present on the pattern, causing the POSIX wrap-
580 per API to be used, the only option-setting sequences that have any
581 effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
582 REG_NOTEOL, respectively, to be passed to regexec().
587 By default, pcretest uses the standard PCRE matching function,
588 pcre[16]_exec() to match each data line. PCRE also supports an alterna-
589 tive matching function, pcre[16]_dfa_test(), which operates in a dif-
590 ferent way, and has some restrictions. The differences between the two
591 functions are described in the pcrematching documentation.
593 If a data line contains the \D escape sequence, or if the command line
594 contains the -dfa option, the alternative matching function is used.
595 This function finds all possible matches at a given point. If, however,
596 the \F escape sequence is present in the data line, it stops after the
597 first match is found. This is always the shortest possible match.
602 This section describes the output when the normal matching function,
603 pcre[16]_exec(), is being used.
605 When a match succeeds, pcretest outputs the list of captured substrings
606 that pcre[16]_exec() returns, starting with number 0 for the string
607 that matched the whole pattern. Otherwise, it outputs "No match" when
608 the return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the
609 partially matching substring when pcre[16]_exec() returns
610 PCRE_ERROR_PARTIAL. (Note that this is the entire substring that was
611 inspected during the partial match; it may include characters before
612 the actual match start if a lookbehind assertion, \K, \b, or \B was
613 involved.) For any other return, pcretest outputs the PCRE negative
614 error number and a short descriptive phrase. If the error is a failed
615 UTF string check, the offset of the start of the failing character and
616 the reason code are also output, provided that the size of the output
617 vector is at least two. Here is an example of an interactive pcretest
618 run.
620 $ pcretest
621 PCRE version 8.13 2011-04-30
623 re> /^abc(\d+)/
624 data> abc123
625 0: abc123
626 1: 123
627 data> xyz
628 No match
630 Unset capturing substrings that are not followed by one that is set are
631 not returned by pcre[16]_exec(), and are not shown by pcretest. In the
632 following example, there are two capturing substrings, but when the
633 first data line is matched, the second, unset substring is not shown.
634 An "internal" unset substring is shown as "<unset>", as for the second
635 data line.
637 re> /(a)|(b)/
638 data> a
639 0: a
640 1: a
641 data> b
642 0: b
643 1: <unset>
644 2: b
646 If the strings contain any non-printing characters, they are output as
647 \xhh escapes if the value is less than 256 and UTF mode is not set.
648 Otherwise they are output as \x{hh...} escapes. See below for the defi-
649 nition of non-printing characters. If the pattern has the /+ modifier,
650 the output for substring 0 is followed by the the rest of the subject
651 string, identified by "0+" like this:
653 re> /cat/+
654 data> cataract
655 0: cat
656 0+ aract
658 If the pattern has the /g or /G modifier, the results of successive
659 matching attempts are output in sequence, like this:
661 re> /\Bi(\w\w)/g
662 data> Mississippi
663 0: iss
664 1: ss
665 0: iss
666 1: ss
667 0: ipp
668 1: pp
670 "No match" is output only if the first match attempt fails. Here is an
671 example of a failure message (the offset 4 that is specified by \>4 is
672 past the end of the subject string):
674 re> /xyz/
675 data> xyz\>4
676 Error -24 (bad offset value)
678 If any of the sequences \C, \G, or \L are present in a data line that
679 is successfully matched, the substrings extracted by the convenience
680 functions are output with C, G, or L after the string number instead of
681 a colon. This is in addition to the normal full list. The string length
682 (that is, the return from the extraction function) is given in paren-
683 theses after each string for \C and \G.
685 Note that whereas patterns can be continued over several lines (a plain
686 ">" prompt is used for continuations), data lines may not. However new-
687 lines can be included in data by means of the \n escape (or \r, \r\n,
688 etc., depending on the newline sequence setting).
693 When the alternative matching function, pcre[16]_dfa_exec(), is used
694 (by means of the \D escape sequence or the -dfa command line option),
695 the output consists of a list of all the matches that start at the
696 first point in the subject where there is at least one match. For exam-
697 ple:
699 re> /(tang|tangerine|tan)/
700 data> yellow tangerine\D
701 0: tangerine
702 1: tang
703 2: tan
705 (Using the normal matching function on this data finds only "tang".)
706 The longest matching string is always given first (and numbered zero).
707 After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
708 lowed by the partially matching substring. (Note that this is the
709 entire substring that was inspected during the partial match; it may
710 include characters before the actual match start if a lookbehind asser-
711 tion, \K, \b, or \B was involved.)
713 If /g is present on the pattern, the search for further matches resumes
714 at the end of the longest match. For example:
716 re> /(tang|tangerine|tan)/g
717 data> yellow tangerine and tangy sultana\D
718 0: tangerine
719 1: tang
720 2: tan
721 0: tang
722 1: tan
723 0: tan
725 Since the matching function does not support substring capture, the
726 escape sequences that are concerned with captured substrings are not
727 relevant.
732 When the alternative matching function has given the PCRE_ERROR_PARTIAL
733 return, indicating that the subject partially matched the pattern, you
734 can restart the match with additional subject data by means of the \R
735 escape sequence. For example:
737 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
738 data> 23ja\P\D
739 Partial match: 23ja
740 data> n05\R\D
741 0: n05
743 For further information about partial matching, see the pcrepartial
744 documentation.
749 If the pattern contains any callout requests, pcretest's callout func-
750 tion is called during matching. This works with both matching func-
751 tions. By default, the called function displays the callout number, the
752 start and current positions in the text at the callout time, and the
753 next pattern item to be tested. For example:
755 --->pqrabcdef
756 0 ^ ^ \d
758 This output indicates that callout number 0 occurred for a match
759 attempt starting at the fourth character of the subject string, when
760 the pointer was at the seventh character of the data, and when the next
761 pattern item was \d. Just one circumflex is output if the start and
762 current positions are the same.
764 Callouts numbered 255 are assumed to be automatic callouts, inserted as
765 a result of the /C pattern modifier. In this case, instead of showing
766 the callout number, the offset in the pattern, preceded by a plus, is
767 output. For example:
769 re> /\d?[A-E]\*/C
770 data> E*
771 --->E*
772 +0 ^ \d?
773 +3 ^ [A-E]
774 +8 ^^ \*
775 +10 ^ ^
776 0: E*
778 If a pattern contains (*MARK) items, an additional line is output when-
779 ever a change of latest mark is passed to the callout function. For
780 example:
782 re> /a(*MARK:X)bc/C
783 data> abc
784 --->abc
785 +0 ^ a
786 +1 ^^ (*MARK:X)
787 +10 ^^ b
788 Latest Mark: X
789 +11 ^ ^ c
790 +12 ^ ^
791 0: abc
793 The mark changes between matching "a" and "b", but stays the same for
794 the rest of the match, so nothing more is output. If, as a result of
795 backtracking, the mark reverts to being unset, the text "<unset>" is
796 output.
798 The callout function in pcretest returns zero (carry on matching) by
799 default, but you can use a \C item in a data line (as described above)
800 to change this and other parameters of the callout.
802 Inserting callouts can be helpful when using pcretest to check compli-
803 cated regular expressions. For further information about callouts, see
804 the pcrecallout documentation.
809 When pcretest is outputting text in the compiled version of a pattern,
810 bytes other than 32-126 are always treated as non-printing characters
811 are are therefore shown as hex escapes.
813 When pcretest is outputting text that is a matched part of a subject
814 string, it behaves in the same way, unless a different locale has been
815 set for the pattern (using the /L modifier). In this case, the
816 isprint() function to distinguish printing and non-printing characters.
821 The facilities described in this section are not available when the
822 POSIX interface to PCRE is being used, that is, when the /P pattern
823 modifier is specified.
825 When the POSIX interface is not in use, you can cause pcretest to write
826 a compiled pattern to a file, by following the modifiers with > and a
827 file name. For example:
829 /pattern/im >/some/file
831 See the pcreprecompile documentation for a discussion about saving and
832 re-using compiled patterns. Note that if the pattern was successfully
833 studied with JIT optimization, the JIT data cannot be saved.
835 The data that is written is binary. The first eight bytes are the
836 length of the compiled pattern data followed by the length of the
837 optional study data, each written as four bytes in big-endian order
838 (most significant byte first). If there is no study data (either the
839 pattern was not studied, or studying did not return any data), the sec-
840 ond length is zero. The lengths are followed by an exact copy of the
841 compiled pattern. If there is additional study data, this (excluding
842 any JIT data) follows immediately after the compiled pattern. After
843 writing the file, pcretest expects to read a new pattern.
845 A saved pattern can be reloaded into pcretest by specifying < and a
846 file name instead of a pattern. The name of the file must not contain a
847 < character, as otherwise pcretest will interpret the line as a pattern
848 delimited by < characters. For example:
850 re> </some/file
851 Compiled pattern loaded from /some/file
852 No study data
854 If the pattern was previously studied with the JIT optimization, the
855 JIT information cannot be saved and restored, and so is lost. When the
856 pattern has been loaded, pcretest proceeds to read data lines in the
857 usual way.
859 You can copy a file written by pcretest to a different host and reload
860 it there, even if the new host has opposite endianness to the one on
861 which the pattern was compiled. For example, you can compile on an i86
862 machine and run on a SPARC machine. When a pattern is reloaded on a
863 host with different endianness, the confirmation message is changed to:
865 Compiled pattern (byte-inverted) loaded from /some/file
867 The test suite contains some saved pre-compiled patterns with different
868 endianness. These are reloaded using "<!" instead of just "<". This
869 suppresses the "(byte-inverted)" text so that the output is the same on
870 all hosts. It also forces debugging output once the pattern has been
871 reloaded.
873 File names for saving and reloading can be absolute or relative, but
874 note that the shell facility of expanding a file name that starts with
875 a tilde (~) is not available.
877 The ability to save and reload files in pcretest is intended for test-
878 ing and experimentation. It is not intended for production use because
879 only a single pattern can be written to a file. Furthermore, there is
880 no facility for supplying custom character tables for use with a
881 reloaded pattern. If the original pattern was compiled with custom
882 tables, an attempt to match a subject string using a reloaded pattern
883 is likely to cause pcretest to crash. Finally, if you attempt to load
884 a file that is not in the correct format, the result is undefined.
889 pcre(3), pcre16(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematch-
890 ing(3), pcrepartial(d), pcrepattern(3), pcreprecompile(3).
895 Philip Hazel
896 University Computing Service
897 Cambridge CB2 3QH, England.
902 Last updated: 21 February 2012
903 Copyright (c) 1997-2012 University of Cambridge.


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