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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. This does not include the size of the pcre
309 block; it is just the actual compiled data. If the pattern is success-
310 fully studied with the PCRE_STUDY_JIT_COMPILE option, the size of the
311 JIT compiled code is also output.
312
313 If the /S modifier appears once, it causes pcre_study() to be called
314 after the expression has been compiled, and the results used when the
315 expression is matched. If /S appears twice, it suppresses studying,
316 even if it was requested externally by the -s command line option. This
317 makes it possible to specify that certain patterns are always studied,
318 and others are never studied, independently of -s. This feature is used
319 in the test files in a few cases where the output is different when the
320 pattern is studied.
321
322 If the /S modifier is immediately followed by a + character, the call
323 to pcre_study() is made with the PCRE_STUDY_JIT_COMPILE option,
324 requesting just-in-time optimization support if it is available. Note
325 that there is also a /+ modifier; it must not be given immediately
326 after /S because this will be misinterpreted. If JIT studying is suc-
327 cessful, it will automatically be used when pcre_exec() is run, except
328 when incompatible run-time options are specified. These include the
329 partial matching options; a complete list is given in the pcrejit docu-
330 mentation. See also the \J escape sequence below for a way of setting
331 the size of the JIT stack.
332
333 The /T modifier must be followed by a single digit. It causes a spe-
334 cific set of built-in character tables to be passed to pcre_compile().
335 It is used in the standard PCRE tests to check behaviour with different
336 character tables. The digit specifies the tables as follows:
337
338 0 the default ASCII tables, as distributed in
339 pcre_chartables.c.dist
340 1 a set of tables defining ISO 8859 characters
341
342 In table 1, some characters whose codes are greater than 128 are iden-
343 tified as letters, digits, spaces, etc.
344
345 Using the POSIX wrapper API
346
347 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
348 rather than its native API. When /P is set, the following modifiers set
349 options for the regcomp() function:
350
351 /i REG_ICASE
352 /m REG_NEWLINE
353 /N REG_NOSUB
354 /s REG_DOTALL )
355 /U REG_UNGREEDY ) These options are not part of
356 /W REG_UCP ) the POSIX standard
357 /8 REG_UTF8 )
358
359 The /+ modifier works as described above. All other modifiers are
360 ignored.
361
362
363 DATA LINES
364
365 Before each data line is passed to pcre_exec(), leading and trailing
366 white space is removed, and it is then scanned for \ escapes. Some of
367 these are pretty esoteric features, intended for checking out some of
368 the more complicated features of PCRE. If you are just testing "ordi-
369 nary" regular expressions, you probably don't need any of these. The
370 following escapes are recognized:
371
372 \a alarm (BEL, \x07)
373 \b backspace (\x08)
374 \e escape (\x27)
375 \f form feed (\x0c)
376 \n newline (\x0a)
377 \qdd set the PCRE_MATCH_LIMIT limit to dd
378 (any number of digits)
379 \r carriage return (\x0d)
380 \t tab (\x09)
381 \v vertical tab (\x0b)
382 \nnn octal character (up to 3 octal digits)
383 always a byte unless > 255 in UTF-8 mode
384 \xhh hexadecimal byte (up to 2 hex digits)
385 \x{hh...} hexadecimal character, any number of digits
386 in UTF-8 mode
387 \A pass the PCRE_ANCHORED option to pcre_exec()
388 or pcre_dfa_exec()
389 \B pass the PCRE_NOTBOL option to pcre_exec()
390 or pcre_dfa_exec()
391 \Cdd call pcre_copy_substring() for substring dd
392 after a successful match (number less than 32)
393 \Cname call pcre_copy_named_substring() for substring
394 "name" after a successful match (name termin-
395 ated by next non alphanumeric character)
396 \C+ show the current captured substrings at callout
397 time
398 \C- do not supply a callout function
399 \C!n return 1 instead of 0 when callout number n is
400 reached
401 \C!n!m return 1 instead of 0 when callout number n is
402 reached for the nth time
403 \C*n pass the number n (may be negative) as callout
404 data; this is used as the callout return value
405 \D use the pcre_dfa_exec() match function
406 \F only shortest match for pcre_dfa_exec()
407 \Gdd call pcre_get_substring() for substring dd
408 after a successful match (number less than 32)
409 \Gname call pcre_get_named_substring() for substring
410 "name" after a successful match (name termin-
411 ated by next non-alphanumeric character)
412 \Jdd set up a JIT stack of dd kilobytes maximum (any
413 number of digits)
414 \L call pcre_get_substringlist() after a
415 successful match
416 \M discover the minimum MATCH_LIMIT and
417 MATCH_LIMIT_RECURSION settings
418 \N pass the PCRE_NOTEMPTY option to pcre_exec()
419 or pcre_dfa_exec(); if used twice, pass the
420 PCRE_NOTEMPTY_ATSTART option
421 \Odd set the size of the output vector passed to
422 pcre_exec() to dd (any number of digits)
423 \P pass the PCRE_PARTIAL_SOFT option to pcre_exec()
424 or pcre_dfa_exec(); if used twice, pass the
425 PCRE_PARTIAL_HARD option
426 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
427 (any number of digits)
428 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
429 \S output details of memory get/free calls during matching
430 \Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
431 or pcre_dfa_exec()
432 \Z pass the PCRE_NOTEOL option to pcre_exec()
433 or pcre_dfa_exec()
434 \? pass the PCRE_NO_UTF8_CHECK option to
435 pcre_exec() or pcre_dfa_exec()
436 \>dd start the match at offset dd (optional "-"; then
437 any number of digits); this sets the startoffset
438 argument for pcre_exec() or pcre_dfa_exec()
439 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
440 or pcre_dfa_exec()
441 \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
442 or pcre_dfa_exec()
443 \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
444 or pcre_dfa_exec()
445 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
446 or pcre_dfa_exec()
447 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
448 or pcre_dfa_exec()
449
450 Note that \xhh always specifies one byte, even in UTF-8 mode; this
451 makes it possible to construct invalid UTF-8 sequences for testing pur-
452 poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
453 UTF-8 mode, generating more than one byte if the value is greater than
454 127. When not in UTF-8 mode, it generates one byte for values less than
455 256, and causes an error for greater values.
456
457 The escapes that specify line ending sequences are literal strings,
458 exactly as shown. No more than one newline setting should be present in
459 any data line.
460
461 A backslash followed by anything else just escapes the anything else.
462 If the very last character is a backslash, it is ignored. This gives a
463 way of passing an empty line as data, since a real empty line termi-
464 nates the data input.
465
466 The \J escape provides a way of setting the maximum stack size that is
467 used by the just-in-time optimization code. It is ignored if JIT opti-
468 mization is not being used. Providing a stack that is larger than the
469 default 32K is necessary only for very complicated patterns.
470
471 If \M is present, pcretest calls pcre_exec() several times, with dif-
472 ferent values in the match_limit and match_limit_recursion fields of
473 the pcre_extra data structure, until it finds the minimum numbers for
474 each parameter that allow pcre_exec() to complete without error.
475 Because this is testing a specific feature of the normal interpretive
476 pcre_exec() execution, the use of any JIT optimization that might have
477 been set up by the /S+ qualifier of -s+ option is disabled.
478
479 The match_limit number is a measure of the amount of backtracking that
480 takes place, and checking it out can be instructive. For most simple
481 matches, the number is quite small, but for patterns with very large
482 numbers of matching possibilities, it can become large very quickly
483 with increasing length of subject string. The match_limit_recursion
484 number is a measure of how much stack (or, if PCRE is compiled with
485 NO_RECURSE, how much heap) memory is needed to complete the match
486 attempt.
487
488 When \O is used, the value specified may be higher or lower than the
489 size set by the -O command line option (or defaulted to 45); \O applies
490 only to the call of pcre_exec() for the line in which it appears.
491
492 If the /P modifier was present on the pattern, causing the POSIX wrap-
493 per API to be used, the only option-setting sequences that have any
494 effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
495 REG_NOTEOL, respectively, to be passed to regexec().
496
497 The use of \x{hh...} to represent UTF-8 characters is not dependent on
498 the use of the /8 modifier on the pattern. It is recognized always.
499 There may be any number of hexadecimal digits inside the braces. The
500 result is from one to six bytes, encoded according to the original
501 UTF-8 rules of RFC 2279. This allows for values in the range 0 to
502 0x7FFFFFFF. Note that not all of those are valid Unicode code points,
503 or indeed valid UTF-8 characters according to the later rules in RFC
504 3629.
505
506
507 THE ALTERNATIVE MATCHING FUNCTION
508
509 By default, pcretest uses the standard PCRE matching function,
510 pcre_exec() to match each data line. From release 6.0, PCRE supports an
511 alternative matching function, pcre_dfa_test(), which operates in a
512 different way, and has some restrictions. The differences between the
513 two functions are described in the pcrematching documentation.
514
515 If a data line contains the \D escape sequence, or if the command line
516 contains the -dfa option, the alternative matching function is called.
517 This function finds all possible matches at a given point. If, however,
518 the \F escape sequence is present in the data line, it stops after the
519 first match is found. This is always the shortest possible match.
520
521
522 DEFAULT OUTPUT FROM PCRETEST
523
524 This section describes the output when the normal matching function,
525 pcre_exec(), is being used.
526
527 When a match succeeds, pcretest outputs the list of captured substrings
528 that pcre_exec() returns, starting with number 0 for the string that
529 matched the whole pattern. Otherwise, it outputs "No match" when the
530 return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
531 tially matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
532 (Note that this is the entire substring that was inspected during the
533 partial match; it may include characters before the actual match start
534 if a lookbehind assertion, \K, \b, or \B was involved.) For any other
535 return, pcretest outputs the PCRE negative error number and a short
536 descriptive phrase. If the error is a failed UTF-8 string check, the
537 byte offset of the start of the failing character and the reason code
538 are also output, provided that the size of the output vector is at
539 least two. Here is an example of an interactive pcretest run.
540
541 $ pcretest
542 PCRE version 8.13 2011-04-30
543
544 re> /^abc(\d+)/
545 data> abc123
546 0: abc123
547 1: 123
548 data> xyz
549 No match
550
551 Unset capturing substrings that are not followed by one that is set are
552 not returned by pcre_exec(), and are not shown by pcretest. In the fol-
553 lowing example, there are two capturing substrings, but when the first
554 data line is matched, the second, unset substring is not shown. An
555 "internal" unset substring is shown as "<unset>", as for the second
556 data line.
557
558 re> /(a)|(b)/
559 data> a
560 0: a
561 1: a
562 data> b
563 0: b
564 1: <unset>
565 2: b
566
567 If the strings contain any non-printing characters, they are output as
568 \0x escapes, or as \x{...} escapes if the /8 modifier was present on
569 the pattern. See below for the definition of non-printing characters.
570 If the pattern has the /+ modifier, the output for substring 0 is fol-
571 lowed by the the rest of the subject string, identified by "0+" like
572 this:
573
574 re> /cat/+
575 data> cataract
576 0: cat
577 0+ aract
578
579 If the pattern has the /g or /G modifier, the results of successive
580 matching attempts are output in sequence, like this:
581
582 re> /\Bi(\w\w)/g
583 data> Mississippi
584 0: iss
585 1: ss
586 0: iss
587 1: ss
588 0: ipp
589 1: pp
590
591 "No match" is output only if the first match attempt fails. Here is an
592 example of a failure message (the offset 4 that is specified by \>4 is
593 past the end of the subject string):
594
595 re> /xyz/
596 data> xyz\>4
597 Error -24 (bad offset value)
598
599 If any of the sequences \C, \G, or \L are present in a data line that
600 is successfully matched, the substrings extracted by the convenience
601 functions are output with C, G, or L after the string number instead of
602 a colon. This is in addition to the normal full list. The string length
603 (that is, the return from the extraction function) is given in paren-
604 theses after each string for \C and \G.
605
606 Note that whereas patterns can be continued over several lines (a plain
607 ">" prompt is used for continuations), data lines may not. However new-
608 lines can be included in data by means of the \n escape (or \r, \r\n,
609 etc., depending on the newline sequence setting).
610
611
612 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
613
614 When the alternative matching function, pcre_dfa_exec(), is used (by
615 means of the \D escape sequence or the -dfa command line option), the
616 output consists of a list of all the matches that start at the first
617 point in the subject where there is at least one match. For example:
618
619 re> /(tang|tangerine|tan)/
620 data> yellow tangerine\D
621 0: tangerine
622 1: tang
623 2: tan
624
625 (Using the normal matching function on this data finds only "tang".)
626 The longest matching string is always given first (and numbered zero).
627 After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
628 lowed by the partially matching substring. (Note that this is the
629 entire substring that was inspected during the partial match; it may
630 include characters before the actual match start if a lookbehind asser-
631 tion, \K, \b, or \B was involved.)
632
633 If /g is present on the pattern, the search for further matches resumes
634 at the end of the longest match. For example:
635
636 re> /(tang|tangerine|tan)/g
637 data> yellow tangerine and tangy sultana\D
638 0: tangerine
639 1: tang
640 2: tan
641 0: tang
642 1: tan
643 0: tan
644
645 Since the matching function does not support substring capture, the
646 escape sequences that are concerned with captured substrings are not
647 relevant.
648
649
650 RESTARTING AFTER A PARTIAL MATCH
651
652 When the alternative matching function has given the PCRE_ERROR_PARTIAL
653 return, indicating that the subject partially matched the pattern, you
654 can restart the match with additional subject data by means of the \R
655 escape sequence. For example:
656
657 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
658 data> 23ja\P\D
659 Partial match: 23ja
660 data> n05\R\D
661 0: n05
662
663 For further information about partial matching, see the pcrepartial
664 documentation.
665
666
667 CALLOUTS
668
669 If the pattern contains any callout requests, pcretest's callout func-
670 tion is called during matching. This works with both matching func-
671 tions. By default, the called function displays the callout number, the
672 start and current positions in the text at the callout time, and the
673 next pattern item to be tested. For example, the output
674
675 --->pqrabcdef
676 0 ^ ^ \d
677
678 indicates that callout number 0 occurred for a match attempt starting
679 at the fourth character of the subject string, when the pointer was at
680 the seventh character of the data, and when the next pattern item was
681 \d. Just one circumflex is output if the start and current positions
682 are the same.
683
684 Callouts numbered 255 are assumed to be automatic callouts, inserted as
685 a result of the /C pattern modifier. In this case, instead of showing
686 the callout number, the offset in the pattern, preceded by a plus, is
687 output. For example:
688
689 re> /\d?[A-E]\*/C
690 data> E*
691 --->E*
692 +0 ^ \d?
693 +3 ^ [A-E]
694 +8 ^^ \*
695 +10 ^ ^
696 0: E*
697
698 If a pattern contains (*MARK) items, an additional line is output when-
699 ever a change of latest mark is passed to the callout function. For
700 example:
701
702 re> /a(*MARK:X)bc/C
703 data> abc
704 --->abc
705 +0 ^ a
706 +1 ^^ (*MARK:X)
707 +10 ^^ b
708 Latest Mark: X
709 +11 ^ ^ c
710 +12 ^ ^
711 0: abc
712
713 The mark changes between matching "a" and "b", but stays the same for
714 the rest of the match, so nothing more is output. If, as a result of
715 backtracking, the mark reverts to being unset, the text "<unset>" is
716 output.
717
718 The callout function in pcretest returns zero (carry on matching) by
719 default, but you can use a \C item in a data line (as described above)
720 to change this and other parameters of the callout.
721
722 Inserting callouts can be helpful when using pcretest to check compli-
723 cated regular expressions. For further information about callouts, see
724 the pcrecallout documentation.
725
726
727 NON-PRINTING CHARACTERS
728
729 When pcretest is outputting text in the compiled version of a pattern,
730 bytes other than 32-126 are always treated as non-printing characters
731 are are therefore shown as hex escapes.
732
733 When pcretest is outputting text that is a matched part of a subject
734 string, it behaves in the same way, unless a different locale has been
735 set for the pattern (using the /L modifier). In this case, the
736 isprint() function to distinguish printing and non-printing characters.
737
738
739 SAVING AND RELOADING COMPILED PATTERNS
740
741 The facilities described in this section are not available when the
742 POSIX interface to PCRE is being used, that is, when the /P pattern
743 modifier is specified.
744
745 When the POSIX interface is not in use, you can cause pcretest to write
746 a compiled pattern to a file, by following the modifiers with > and a
747 file name. For example:
748
749 /pattern/im >/some/file
750
751 See the pcreprecompile documentation for a discussion about saving and
752 re-using compiled patterns. Note that if the pattern was successfully
753 studied with JIT optimization, the JIT data cannot be saved.
754
755 The data that is written is binary. The first eight bytes are the
756 length of the compiled pattern data followed by the length of the
757 optional study data, each written as four bytes in big-endian order
758 (most significant byte first). If there is no study data (either the
759 pattern was not studied, or studying did not return any data), the sec-
760 ond length is zero. The lengths are followed by an exact copy of the
761 compiled pattern. If there is additional study data, this (excluding
762 any JIT data) follows immediately after the compiled pattern. After
763 writing the file, pcretest expects to read a new pattern.
764
765 A saved pattern can be reloaded into pcretest by specifying < and a
766 file name instead of a pattern. The name of the file must not contain a
767 < character, as otherwise pcretest will interpret the line as a pattern
768 delimited by < characters. For example:
769
770 re> </some/file
771 Compiled pattern loaded from /some/file
772 No study data
773
774 If the pattern was previously studied with the JIT optimization, the
775 JIT information cannot be saved and restored, and so is lost. When the
776 pattern has been loaded, pcretest proceeds to read data lines in the
777 usual way.
778
779 You can copy a file written by pcretest to a different host and reload
780 it there, even if the new host has opposite endianness to the one on
781 which the pattern was compiled. For example, you can compile on an i86
782 machine and run on a SPARC machine.
783
784 File names for saving and reloading can be absolute or relative, but
785 note that the shell facility of expanding a file name that starts with
786 a tilde (~) is not available.
787
788 The ability to save and reload files in pcretest is intended for test-
789 ing and experimentation. It is not intended for production use because
790 only a single pattern can be written to a file. Furthermore, there is
791 no facility for supplying custom character tables for use with a
792 reloaded pattern. If the original pattern was compiled with custom
793 tables, an attempt to match a subject string using a reloaded pattern
794 is likely to cause pcretest to crash. Finally, if you attempt to load
795 a file that is not in the correct format, the result is undefined.
796
797
798 SEE ALSO
799
800 pcre(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematching(3), pcrepar-
801 tial(d), pcrepattern(3), pcreprecompile(3).
802
803
804 AUTHOR
805
806 Philip Hazel
807 University Computing Service
808 Cambridge CB2 3QH, England.
809
810
811 REVISION
812
813 Last updated: 02 December 2011
814 Copyright (c) 1997-2011 University of Cambridge.

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