ViewVC logotype

Contents of /code/trunk/doc/pcretest.1

Parent Directory Parent Directory | Revision Log Revision Log

Revision 518 - (show annotations)
Tue May 18 15:47:01 2010 UTC (10 years, 9 months ago) by ph10
File size: 29697 byte(s)
Added PCRE_UCP and related stuff to make \w etc use Unicode properties.
3 pcretest - a program for testing Perl-compatible regular expressions.
5 .rs
6 .sp
7 .B pcretest "[options] [source] [destination]"
8 .sp
9 \fBpcretest\fP was written as a test program for the PCRE regular expression
10 library itself, but it can also be used for experimenting with regular
11 expressions. This document describes the features of the test program; for
12 details of the regular expressions themselves, see the
13 .\" HREF
14 \fBpcrepattern\fP
15 .\"
16 documentation. For details of the PCRE library function calls and their
17 options, see the
18 .\" HREF
19 \fBpcreapi\fP
20 .\"
21 documentation.
22 .
23 .
25 .rs
26 .TP 10
27 \fB-b\fP
28 Behave as if each regex has the \fB/B\fP (show bytecode) modifier; the internal
29 form is output after compilation.
30 .TP 10
31 \fB-C\fP
32 Output the version number of the PCRE library, and all available information
33 about the optional features that are included, and then exit.
34 .TP 10
35 \fB-d\fP
36 Behave as if each regex has the \fB/D\fP (debug) modifier; the internal
37 form and information about the compiled pattern is output after compilation;
38 \fB-d\fP is equivalent to \fB-b -i\fP.
39 .TP 10
40 \fB-dfa\fP
41 Behave as if each data line contains the \eD escape sequence; this causes the
42 alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the
43 standard \fBpcre_exec()\fP function (more detail is given below).
44 .TP 10
45 \fB-help\fP
46 Output a brief summary these options and then exit.
47 .TP 10
48 \fB-i\fP
49 Behave as if each regex has the \fB/I\fP modifier; information about the
50 compiled pattern is given after compilation.
51 .TP 10
52 \fB-M\fP
53 Behave as if each data line contains the \eM escape sequence; this causes
54 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
55 calling \fBpcre_exec()\fP repeatedly with different limits.
56 .TP 10
57 \fB-m\fP
58 Output the size of each compiled pattern after it has been compiled. This is
59 equivalent to adding \fB/M\fP to each regular expression. For compatibility
60 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
61 .TP 10
62 \fB-o\fP \fIosize\fP
63 Set the number of elements in the output vector that is used when calling
64 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
65 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
66 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
67 changed for individual matching calls by including \eO in the data line (see
68 below).
69 .TP 10
70 \fB-p\fP
71 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
72 used to call PCRE. None of the other options has any effect when \fB-p\fP is
73 set.
74 .TP 10
75 \fB-q\fP
76 Do not output the version number of \fBpcretest\fP at the start of execution.
77 .TP 10
78 \fB-S\fP \fIsize\fP
79 On Unix-like systems, set the size of the runtime stack to \fIsize\fP
80 megabytes.
81 .TP 10
82 \fB-t\fP
83 Run each compile, study, and match many times with a timer, and output
84 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
85 \fB-t\fP, because you will then get the size output a zillion times, and the
86 timing will be distorted. You can control the number of iterations that are
87 used for timing by following \fB-t\fP with a number (as a separate item on the
88 command line). For example, "-t 1000" would iterate 1000 times. The default is
89 to iterate 500000 times.
90 .TP 10
91 \fB-tm\fP
92 This is like \fB-t\fP except that it times only the matching phase, not the
93 compile or study phases.
94 .
95 .
97 .rs
98 .sp
99 If \fBpcretest\fP is given two filename arguments, it reads from the first and
100 writes to the second. If it is given only one filename argument, it reads from
101 that file and writes to stdout. Otherwise, it reads from stdin and writes to
102 stdout, and prompts for each line of input, using "re>" to prompt for regular
103 expressions, and "data>" to prompt for data lines.
104 .P
105 When \fBpcretest\fP is built, a configuration option can specify that it should
106 be linked with the \fBlibreadline\fP library. When this is done, if the input
107 is from a terminal, it is read using the \fBreadline()\fP function. This
108 provides line-editing and history facilities. The output from the \fB-help\fP
109 option states whether or not \fBreadline()\fP will be used.
110 .P
111 The program handles any number of sets of input on a single input file. Each
112 set starts with a regular expression, and continues with any number of data
113 lines to be matched against the pattern.
114 .P
115 Each data line is matched separately and independently. If you want to do
116 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
117 etc., depending on the newline setting) in a single line of input to encode the
118 newline sequences. There is no limit on the length of data lines; the input
119 buffer is automatically extended if it is too small.
120 .P
121 An empty line signals the end of the data lines, at which point a new regular
122 expression is read. The regular expressions are given enclosed in any
123 non-alphanumeric delimiters other than backslash, for example:
124 .sp
125 /(a|bc)x+yz/
126 .sp
127 White space before the initial delimiter is ignored. A regular expression may
128 be continued over several input lines, in which case the newline characters are
129 included within it. It is possible to include the delimiter within the pattern
130 by escaping it, for example
131 .sp
132 /abc\e/def/
133 .sp
134 If you do so, the escape and the delimiter form part of the pattern, but since
135 delimiters are always non-alphanumeric, this does not affect its interpretation.
136 If the terminating delimiter is immediately followed by a backslash, for
137 example,
138 .sp
139 /abc/\e
140 .sp
141 then a backslash is added to the end of the pattern. This is done to provide a
142 way of testing the error condition that arises if a pattern finishes with a
143 backslash, because
144 .sp
145 /abc\e/
146 .sp
147 is interpreted as the first line of a pattern that starts with "abc/", causing
148 pcretest to read the next line as a continuation of the regular expression.
149 .
150 .
152 .rs
153 .sp
154 A pattern may be followed by any number of modifiers, which are mostly single
155 characters. Following Perl usage, these are referred to below as, for example,
156 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
157 always be a slash, and no slash is used when writing modifiers. Whitespace may
158 appear between the final pattern delimiter and the first modifier, and between
159 the modifiers themselves.
160 .P
161 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
162 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
163 \fBpcre_compile()\fP is called. These four modifier letters have the same
164 effect as they do in Perl. For example:
165 .sp
166 /caseless/i
167 .sp
168 The following table shows additional modifiers for setting PCRE compile-time
169 options that do not correspond to anything in Perl:
170 .sp
171 \fB/8\fP PCRE_UTF8
180 \fB/W\fP PCRE_UCP
183 \fB/<cr>\fP PCRE_NEWLINE_CR
184 \fB/<lf>\fP PCRE_NEWLINE_LF
185 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
186 \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
187 \fB/<any>\fP PCRE_NEWLINE_ANY
188 \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
189 \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
190 .sp
191 The modifiers that are enclosed in angle brackets are literal strings as shown,
192 including the angle brackets, but the letters can be in either case. This
193 example sets multiline matching with CRLF as the line ending sequence:
194 .sp
195 /^abc/m<crlf>
196 .sp
197 As well as turning on the PCRE_UTF8 option, the \fB/8\fP modifier also causes
198 any non-printing characters in output strings to be printed using the
199 \ex{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
200 options are given in the
201 .\" HREF
202 \fBpcreapi\fP
203 .\"
204 documentation.
205 .
206 .
207 .SS "Finding all matches in a string"
208 .rs
209 .sp
210 Searching for all possible matches within each subject string can be requested
211 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
212 again to search the remainder of the subject string. The difference between
213 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
214 \fBpcre_exec()\fP to start searching at a new point within the entire string
215 (which is in effect what Perl does), whereas the latter passes over a shortened
216 substring. This makes a difference to the matching process if the pattern
217 begins with a lookbehind assertion (including \eb or \eB).
218 .P
219 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
220 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
221 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
222 same point. If this second match fails, the start offset is advanced by one
223 character, and the normal match is retried. This imitates the way Perl handles
224 such cases when using the \fB/g\fP modifier or the \fBsplit()\fP function.
225 .
226 .
227 .SS "Other modifiers"
228 .rs
229 .sp
230 There are yet more modifiers for controlling the way \fBpcretest\fP
231 operates.
232 .P
233 The \fB/+\fP modifier requests that as well as outputting the substring that
234 matched the entire pattern, pcretest should in addition output the remainder of
235 the subject string. This is useful for tests where the subject contains
236 multiple copies of the same substring.
237 .P
238 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
239 output a representation of the compiled byte code after compilation. Normally
240 this information contains length and offset values; however, if \fB/Z\fP is
241 also present, this data is replaced by spaces. This is a special feature for
242 use in the automatic test scripts; it ensures that the same output is generated
243 for different internal link sizes.
244 .P
245 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
246 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
247 .P
248 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
249 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
250 facility is for testing the feature in PCRE that allows it to execute patterns
251 that were compiled on a host with a different endianness. This feature is not
252 available when the POSIX interface to PCRE is being used, that is, when the
253 \fB/P\fP pattern modifier is specified. See also the section about saving and
254 reloading compiled patterns below.
255 .P
256 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
257 compiled pattern (whether it is anchored, has a fixed first character, and
258 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
259 pattern. If the pattern is studied, the results of that are also output.
260 .P
261 The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking
262 control verbs that are returned from calls to \fBpcre_exec()\fP. It causes
263 \fBpcretest\fP to create a \fBpcre_extra\fP block if one has not already been
264 created by a call to \fBpcre_study()\fP, and to set the PCRE_EXTRA_MARK flag
265 and the \fBmark\fP field within it, every time that \fBpcre_exec()\fP is
266 called. If the variable that the \fBmark\fP field points to is non-NULL for a
267 match, non-match, or partial match, \fBpcretest\fP prints the string to which
268 it points. For a match, this is shown on a line by itself, tagged with "MK:".
269 For a non-match it is added to the message.
270 .P
271 The \fB/L\fP modifier must be followed directly by the name of a locale, for
272 example,
273 .sp
274 /pattern/Lfr_FR
275 .sp
276 For this reason, it must be the last modifier. The given locale is set,
277 \fBpcre_maketables()\fP is called to build a set of character tables for the
278 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
279 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
280 pointer; that is, \fB/L\fP applies only to the expression on which it appears.
281 .P
282 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
283 pattern to be output.
284 .P
285 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
286 expression has been compiled, and the results used when the expression is
287 matched.
288 .
289 .
290 .SS "Using the POSIX wrapper API"
291 .rs
292 .sp
293 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
294 API rather than its native API. When \fB/P\fP is set, the following modifiers
295 set options for the \fBregcomp()\fP function:
296 .sp
297 /i REG_ICASE
300 /s REG_DOTALL )
301 /U REG_UNGREEDY ) These options are not part of
302 /W REG_UCP ) the POSIX standard
303 /8 REG_UTF8 )
304 .sp
305 The \fB/+\fP modifier works as described above. All other modifiers are
306 ignored.
307 .
308 .
310 .rs
311 .sp
312 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
313 whitespace is removed, and it is then scanned for \e escapes. Some of these are
314 pretty esoteric features, intended for checking out some of the more
315 complicated features of PCRE. If you are just testing "ordinary" regular
316 expressions, you probably don't need any of these. The following escapes are
317 recognized:
318 .sp
319 \ea alarm (BEL, \ex07)
320 \eb backspace (\ex08)
321 \ee escape (\ex27)
322 \ef formfeed (\ex0c)
323 \en newline (\ex0a)
324 .\" JOIN
325 \eqdd set the PCRE_MATCH_LIMIT limit to dd
326 (any number of digits)
327 \er carriage return (\ex0d)
328 \et tab (\ex09)
329 \ev vertical tab (\ex0b)
330 \ennn octal character (up to 3 octal digits)
331 \exhh hexadecimal character (up to 2 hex digits)
332 .\" JOIN
333 \ex{hh...} hexadecimal character, any number of digits
334 in UTF-8 mode
335 .\" JOIN
336 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
337 or \fBpcre_dfa_exec()\fP
338 .\" JOIN
339 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
340 or \fBpcre_dfa_exec()\fP
341 .\" JOIN
342 \eCdd call pcre_copy_substring() for substring dd
343 after a successful match (number less than 32)
344 .\" JOIN
345 \eCname call pcre_copy_named_substring() for substring
346 "name" after a successful match (name termin-
347 ated by next non alphanumeric character)
348 .\" JOIN
349 \eC+ show the current captured substrings at callout
350 time
351 \eC- do not supply a callout function
352 .\" JOIN
353 \eC!n return 1 instead of 0 when callout number n is
354 reached
355 .\" JOIN
356 \eC!n!m return 1 instead of 0 when callout number n is
357 reached for the nth time
358 .\" JOIN
359 \eC*n pass the number n (may be negative) as callout
360 data; this is used as the callout return value
361 \eD use the \fBpcre_dfa_exec()\fP match function
362 \eF only shortest match for \fBpcre_dfa_exec()\fP
363 .\" JOIN
364 \eGdd call pcre_get_substring() for substring dd
365 after a successful match (number less than 32)
366 .\" JOIN
367 \eGname call pcre_get_named_substring() for substring
368 "name" after a successful match (name termin-
369 ated by next non-alphanumeric character)
370 .\" JOIN
371 \eL call pcre_get_substringlist() after a
372 successful match
373 .\" JOIN
374 \eM discover the minimum MATCH_LIMIT and
376 .\" JOIN
377 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
378 or \fBpcre_dfa_exec()\fP; if used twice, pass the
380 .\" JOIN
381 \eOdd set the size of the output vector passed to
382 \fBpcre_exec()\fP to dd (any number of digits)
383 .\" JOIN
384 \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP
385 or \fBpcre_dfa_exec()\fP; if used twice, pass the
387 .\" JOIN
388 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
389 (any number of digits)
390 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
391 \eS output details of memory get/free calls during matching
392 .\" JOIN
393 \eY pass the PCRE_NO_START_OPTIMIZE option to \fBpcre_exec()\fP
394 or \fBpcre_dfa_exec()\fP
395 .\" JOIN
396 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
397 or \fBpcre_dfa_exec()\fP
398 .\" JOIN
399 \e? pass the PCRE_NO_UTF8_CHECK option to
400 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
401 \e>dd start the match at offset dd (any number of digits);
402 .\" JOIN
403 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
404 or \fBpcre_dfa_exec()\fP
405 .\" JOIN
406 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
407 or \fBpcre_dfa_exec()\fP
408 .\" JOIN
409 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
410 or \fBpcre_dfa_exec()\fP
411 .\" JOIN
412 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
413 or \fBpcre_dfa_exec()\fP
414 .\" JOIN
415 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
416 or \fBpcre_dfa_exec()\fP
417 .\" JOIN
418 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
419 or \fBpcre_dfa_exec()\fP
420 .sp
421 The escapes that specify line ending sequences are literal strings, exactly as
422 shown. No more than one newline setting should be present in any data line.
423 .P
424 A backslash followed by anything else just escapes the anything else. If
425 the very last character is a backslash, it is ignored. This gives a way of
426 passing an empty line as data, since a real empty line terminates the data
427 input.
428 .P
429 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
430 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
431 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
432 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
433 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
434 place, and checking it out can be instructive. For most simple matches, the
435 number is quite small, but for patterns with very large numbers of matching
436 possibilities, it can become large very quickly with increasing length of
437 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
438 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
439 to complete the match attempt.
440 .P
441 When \eO is used, the value specified may be higher or lower than the size set
442 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
443 the call of \fBpcre_exec()\fP for the line in which it appears.
444 .P
445 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
446 API to be used, the only option-setting sequences that have any effect are \eB,
447 \eN, and \eZ, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
448 to be passed to \fBregexec()\fP.
449 .P
450 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
451 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
452 any number of hexadecimal digits inside the braces. The result is from one to
453 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
454 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
455 valid Unicode code points, or indeed valid UTF-8 characters according to the
456 later rules in RFC 3629.
457 .
458 .
460 .rs
461 .sp
462 By default, \fBpcretest\fP uses the standard PCRE matching function,
463 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
464 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
465 different way, and has some restrictions. The differences between the two
466 functions are described in the
467 .\" HREF
468 \fBpcrematching\fP
469 .\"
470 documentation.
471 .P
472 If a data line contains the \eD escape sequence, or if the command line
473 contains the \fB-dfa\fP option, the alternative matching function is called.
474 This function finds all possible matches at a given point. If, however, the \eF
475 escape sequence is present in the data line, it stops after the first match is
476 found. This is always the shortest possible match.
477 .
478 .
480 .rs
481 .sp
482 This section describes the output when the normal matching function,
483 \fBpcre_exec()\fP, is being used.
484 .P
485 When a match succeeds, pcretest outputs the list of captured substrings that
486 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
487 the whole pattern. Otherwise, it outputs "No match" when the return is
488 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
489 substring when \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL. For any other
490 returns, it outputs the PCRE negative error number. Here is an example of an
491 interactive \fBpcretest\fP run.
492 .sp
493 $ pcretest
494 PCRE version 7.0 30-Nov-2006
495 .sp
496 re> /^abc(\ed+)/
497 data> abc123
498 0: abc123
499 1: 123
500 data> xyz
501 No match
502 .sp
503 Note that unset capturing substrings that are not followed by one that is set
504 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
505 the following example, there are two capturing substrings, but when the first
506 data line is matched, the second, unset substring is not shown. An "internal"
507 unset substring is shown as "<unset>", as for the second data line.
508 .sp
509 re> /(a)|(b)/
510 data> a
511 0: a
512 1: a
513 data> b
514 0: b
515 1: <unset>
516 2: b
517 .sp
518 If the strings contain any non-printing characters, they are output as \e0x
519 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
520 pattern. See below for the definition of non-printing characters. If the
521 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
522 the the rest of the subject string, identified by "0+" like this:
523 .sp
524 re> /cat/+
525 data> cataract
526 0: cat
527 0+ aract
528 .sp
529 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
530 matching attempts are output in sequence, like this:
531 .sp
532 re> /\eBi(\ew\ew)/g
533 data> Mississippi
534 0: iss
535 1: ss
536 0: iss
537 1: ss
538 0: ipp
539 1: pp
540 .sp
541 "No match" is output only if the first match attempt fails.
542 .P
543 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
544 data line that is successfully matched, the substrings extracted by the
545 convenience functions are output with C, G, or L after the string number
546 instead of a colon. This is in addition to the normal full list. The string
547 length (that is, the return from the extraction function) is given in
548 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
549 .P
550 Note that whereas patterns can be continued over several lines (a plain ">"
551 prompt is used for continuations), data lines may not. However newlines can be
552 included in data by means of the \en escape (or \er, \er\en, etc., depending on
553 the newline sequence setting).
554 .
555 .
556 .
558 .rs
559 .sp
560 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
561 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
562 output consists of a list of all the matches that start at the first point in
563 the subject where there is at least one match. For example:
564 .sp
565 re> /(tang|tangerine|tan)/
566 data> yellow tangerine\eD
567 0: tangerine
568 1: tang
569 2: tan
570 .sp
571 (Using the normal matching function on this data finds only "tang".) The
572 longest matching string is always given first (and numbered zero). After a
573 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
574 partially matching substring.
575 .P
576 If \fB/g\fP is present on the pattern, the search for further matches resumes
577 at the end of the longest match. For example:
578 .sp
579 re> /(tang|tangerine|tan)/g
580 data> yellow tangerine and tangy sultana\eD
581 0: tangerine
582 1: tang
583 2: tan
584 0: tang
585 1: tan
586 0: tan
587 .sp
588 Since the matching function does not support substring capture, the escape
589 sequences that are concerned with captured substrings are not relevant.
590 .
591 .
593 .rs
594 .sp
595 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
596 indicating that the subject partially matched the pattern, you can restart the
597 match with additional subject data by means of the \eR escape sequence. For
598 example:
599 .sp
600 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
601 data> 23ja\eP\eD
602 Partial match: 23ja
603 data> n05\eR\eD
604 0: n05
605 .sp
606 For further information about partial matching, see the
607 .\" HREF
608 \fBpcrepartial\fP
609 .\"
610 documentation.
611 .
612 .
614 .rs
615 .sp
616 If the pattern contains any callout requests, \fBpcretest\fP's callout function
617 is called during matching. This works with both matching functions. By default,
618 the called function displays the callout number, the start and current
619 positions in the text at the callout time, and the next pattern item to be
620 tested. For example, the output
621 .sp
622 --->pqrabcdef
623 0 ^ ^ \ed
624 .sp
625 indicates that callout number 0 occurred for a match attempt starting at the
626 fourth character of the subject string, when the pointer was at the seventh
627 character of the data, and when the next pattern item was \ed. Just one
628 circumflex is output if the start and current positions are the same.
629 .P
630 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
631 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
632 callout number, the offset in the pattern, preceded by a plus, is output. For
633 example:
634 .sp
635 re> /\ed?[A-E]\e*/C
636 data> E*
637 --->E*
638 +0 ^ \ed?
639 +3 ^ [A-E]
640 +8 ^^ \e*
641 +10 ^ ^
642 0: E*
643 .sp
644 The callout function in \fBpcretest\fP returns zero (carry on matching) by
645 default, but you can use a \eC item in a data line (as described above) to
646 change this.
647 .P
648 Inserting callouts can be helpful when using \fBpcretest\fP to check
649 complicated regular expressions. For further information about callouts, see
650 the
651 .\" HREF
652 \fBpcrecallout\fP
653 .\"
654 documentation.
655 .
656 .
657 .
659 .rs
660 .sp
661 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
662 bytes other than 32-126 are always treated as non-printing characters are are
663 therefore shown as hex escapes.
664 .P
665 When \fBpcretest\fP is outputting text that is a matched part of a subject
666 string, it behaves in the same way, unless a different locale has been set for
667 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
668 function to distinguish printing and non-printing characters.
669 .
670 .
671 .
673 .rs
674 .sp
675 The facilities described in this section are not available when the POSIX
676 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
677 specified.
678 .P
679 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
680 compiled pattern to a file, by following the modifiers with > and a file name.
681 For example:
682 .sp
683 /pattern/im >/some/file
684 .sp
685 See the
686 .\" HREF
687 \fBpcreprecompile\fP
688 .\"
689 documentation for a discussion about saving and re-using compiled patterns.
690 .P
691 The data that is written is binary. The first eight bytes are the length of the
692 compiled pattern data followed by the length of the optional study data, each
693 written as four bytes in big-endian order (most significant byte first). If
694 there is no study data (either the pattern was not studied, or studying did not
695 return any data), the second length is zero. The lengths are followed by an
696 exact copy of the compiled pattern. If there is additional study data, this
697 follows immediately after the compiled pattern. After writing the file,
698 \fBpcretest\fP expects to read a new pattern.
699 .P
700 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
701 name instead of a pattern. The name of the file must not contain a < character,
702 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
703 characters.
704 For example:
705 .sp
706 re> </some/file
707 Compiled regex loaded from /some/file
708 No study data
709 .sp
710 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
711 the usual way.
712 .P
713 You can copy a file written by \fBpcretest\fP to a different host and reload it
714 there, even if the new host has opposite endianness to the one on which the
715 pattern was compiled. For example, you can compile on an i86 machine and run on
716 a SPARC machine.
717 .P
718 File names for saving and reloading can be absolute or relative, but note that
719 the shell facility of expanding a file name that starts with a tilde (~) is not
720 available.
721 .P
722 The ability to save and reload files in \fBpcretest\fP is intended for testing
723 and experimentation. It is not intended for production use because only a
724 single pattern can be written to a file. Furthermore, there is no facility for
725 supplying custom character tables for use with a reloaded pattern. If the
726 original pattern was compiled with custom tables, an attempt to match a subject
727 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
728 Finally, if you attempt to load a file that is not in the correct format, the
729 result is undefined.
730 .
731 .
732 .SH "SEE ALSO"
733 .rs
734 .sp
735 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
736 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
737 .
738 .
740 .rs
741 .sp
742 .nf
743 Philip Hazel
744 University Computing Service
745 Cambridge CB2 3QH, England.
746 .fi
747 .
748 .
750 .rs
751 .sp
752 .nf
753 Last updated: 16 May 2010
754 Copyright (c) 1997-2010 University of Cambridge.
755 .fi


Name Value
svn:eol-style native
svn:keywords "Author Date Id Revision Url"

  ViewVC Help
Powered by ViewVC 1.1.5