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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 Output the size of each compiled pattern after it has been compiled. This is
54 equivalent to adding \fB/M\fP to each regular expression. For compatibility
55 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
56 .TP 10
57 \fB-o\fP \fIosize\fP
58 Set the number of elements in the output vector that is used when calling
59 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
60 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
61 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
62 changed for individual matching calls by including \eO in the data line (see
63 below).
64 .TP 10
65 \fB-p\fP
66 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
67 used to call PCRE. None of the other options has any effect when \fB-p\fP is
68 set.
69 .TP 10
70 \fB-q\fP
71 Do not output the version number of \fBpcretest\fP at the start of execution.
72 .TP 10
73 \fB-S\fP \fIsize\fP
74 On Unix-like systems, set the size of the runtime stack to \fIsize\fP
75 megabytes.
76 .TP 10
77 \fB-t\fP
78 Run each compile, study, and match many times with a timer, and output
79 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
80 \fB-t\fP, because you will then get the size output a zillion times, and the
81 timing will be distorted. You can control the number of iterations that are
82 used for timing by following \fB-t\fP with a number (as a separate item on the
83 command line). For example, "-t 1000" would iterate 1000 times. The default is
84 to iterate 500000 times.
85 .TP 10
86 \fB-tm\fP
87 This is like \fB-t\fP except that it times only the matching phase, not the
88 compile or study phases.
89 .
90 .
92 .rs
93 .sp
94 If \fBpcretest\fP is given two filename arguments, it reads from the first and
95 writes to the second. If it is given only one filename argument, it reads from
96 that file and writes to stdout. Otherwise, it reads from stdin and writes to
97 stdout, and prompts for each line of input, using "re>" to prompt for regular
98 expressions, and "data>" to prompt for data lines.
99 .P
100 When \fBpcretest\fP is built, a configuration option can specify that it should
101 be linked with the \fBlibreadline\fP library. When this is done, if the input
102 is from a terminal, it is read using the \fBreadline()\fP function. This
103 provides line-editing and history facilities. The output from the \fB-help\fP
104 option states whether or not \fBreadline()\fP will be used.
105 .P
106 The program handles any number of sets of input on a single input file. Each
107 set starts with a regular expression, and continues with any number of data
108 lines to be matched against the pattern.
109 .P
110 Each data line is matched separately and independently. If you want to do
111 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
112 etc., depending on the newline setting) in a single line of input to encode the
113 newline sequences. There is no limit on the length of data lines; the input
114 buffer is automatically extended if it is too small.
115 .P
116 An empty line signals the end of the data lines, at which point a new regular
117 expression is read. The regular expressions are given enclosed in any
118 non-alphanumeric delimiters other than backslash, for example:
119 .sp
120 /(a|bc)x+yz/
121 .sp
122 White space before the initial delimiter is ignored. A regular expression may
123 be continued over several input lines, in which case the newline characters are
124 included within it. It is possible to include the delimiter within the pattern
125 by escaping it, for example
126 .sp
127 /abc\e/def/
128 .sp
129 If you do so, the escape and the delimiter form part of the pattern, but since
130 delimiters are always non-alphanumeric, this does not affect its interpretation.
131 If the terminating delimiter is immediately followed by a backslash, for
132 example,
133 .sp
134 /abc/\e
135 .sp
136 then a backslash is added to the end of the pattern. This is done to provide a
137 way of testing the error condition that arises if a pattern finishes with a
138 backslash, because
139 .sp
140 /abc\e/
141 .sp
142 is interpreted as the first line of a pattern that starts with "abc/", causing
143 pcretest to read the next line as a continuation of the regular expression.
144 .
145 .
147 .rs
148 .sp
149 A pattern may be followed by any number of modifiers, which are mostly single
150 characters. Following Perl usage, these are referred to below as, for example,
151 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
152 always be a slash, and no slash is used when writing modifiers. Whitespace may
153 appear between the final pattern delimiter and the first modifier, and between
154 the modifiers themselves.
155 .P
156 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
157 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
158 \fBpcre_compile()\fP is called. These four modifier letters have the same
159 effect as they do in Perl. For example:
160 .sp
161 /caseless/i
162 .sp
163 The following table shows additional modifiers for setting PCRE options that do
164 not correspond to anything in Perl:
165 .sp
175 \fB/<cr>\fP PCRE_NEWLINE_CR
176 \fB/<lf>\fP PCRE_NEWLINE_LF
177 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
178 \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
179 \fB/<any>\fP PCRE_NEWLINE_ANY
180 \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
181 \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
182 .sp
183 Those specifying line ending sequences are literal strings as shown, but the
184 letters can be in either case. This example sets multiline matching with CRLF
185 as the line ending sequence:
186 .sp
187 /^abc/m<crlf>
188 .sp
189 Details of the meanings of these PCRE options are given in the
190 .\" HREF
191 \fBpcreapi\fP
192 .\"
193 documentation.
194 .
195 .
196 .SS "Finding all matches in a string"
197 .rs
198 .sp
199 Searching for all possible matches within each subject string can be requested
200 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
201 again to search the remainder of the subject string. The difference between
202 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
203 \fBpcre_exec()\fP to start searching at a new point within the entire string
204 (which is in effect what Perl does), whereas the latter passes over a shortened
205 substring. This makes a difference to the matching process if the pattern
206 begins with a lookbehind assertion (including \eb or \eB).
207 .P
208 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
209 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
210 flags set in order to search for another, non-empty, match at the same point.
211 If this second match fails, the start offset is advanced by one, and the normal
212 match is retried. This imitates the way Perl handles such cases when using the
213 \fB/g\fP modifier or the \fBsplit()\fP function.
214 .
215 .
216 .SS "Other modifiers"
217 .rs
218 .sp
219 There are yet more modifiers for controlling the way \fBpcretest\fP
220 operates.
221 .P
222 The \fB/+\fP modifier requests that as well as outputting the substring that
223 matched the entire pattern, pcretest should in addition output the remainder of
224 the subject string. This is useful for tests where the subject contains
225 multiple copies of the same substring.
226 .P
227 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
228 output a representation of the compiled byte code after compilation. Normally
229 this information contains length and offset values; however, if \fB/Z\fP is
230 also present, this data is replaced by spaces. This is a special feature for
231 use in the automatic test scripts; it ensures that the same output is generated
232 for different internal link sizes.
233 .P
234 The \fB/L\fP modifier must be followed directly by the name of a locale, for
235 example,
236 .sp
237 /pattern/Lfr_FR
238 .sp
239 For this reason, it must be the last modifier. The given locale is set,
240 \fBpcre_maketables()\fP is called to build a set of character tables for the
241 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
242 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
243 pointer; that is, \fB/L\fP applies only to the expression on which it appears.
244 .P
245 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
246 compiled pattern (whether it is anchored, has a fixed first character, and
247 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
248 pattern. If the pattern is studied, the results of that are also output.
249 .P
250 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
251 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
252 .P
253 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
254 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
255 facility is for testing the feature in PCRE that allows it to execute patterns
256 that were compiled on a host with a different endianness. This feature is not
257 available when the POSIX interface to PCRE is being used, that is, when the
258 \fB/P\fP pattern modifier is specified. See also the section about saving and
259 reloading compiled patterns below.
260 .P
261 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
262 expression has been compiled, and the results used when the expression is
263 matched.
264 .P
265 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
266 pattern to be output.
267 .P
268 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
269 API rather than its native API. When this is done, all other modifiers except
270 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
271 present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
272 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
273 .P
274 The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
275 option set. This turns on support for UTF-8 character handling in PCRE,
276 provided that it was compiled with this support enabled. This modifier also
277 causes any non-printing characters in output strings to be printed using the
278 \ex{hh...} notation if they are valid UTF-8 sequences.
279 .P
280 If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
281 call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
282 checking of the string for UTF-8 validity.
283 .
284 .
286 .rs
287 .sp
288 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
289 whitespace is removed, and it is then scanned for \e escapes. Some of these are
290 pretty esoteric features, intended for checking out some of the more
291 complicated features of PCRE. If you are just testing "ordinary" regular
292 expressions, you probably don't need any of these. The following escapes are
293 recognized:
294 .sp
295 \ea alarm (BEL, \ex07)
296 \eb backspace (\ex08)
297 \ee escape (\ex27)
298 \ef formfeed (\ex0c)
299 \en newline (\ex0a)
300 .\" JOIN
301 \eqdd set the PCRE_MATCH_LIMIT limit to dd
302 (any number of digits)
303 \er carriage return (\ex0d)
304 \et tab (\ex09)
305 \ev vertical tab (\ex0b)
306 \ennn octal character (up to 3 octal digits)
307 \exhh hexadecimal character (up to 2 hex digits)
308 .\" JOIN
309 \ex{hh...} hexadecimal character, any number of digits
310 in UTF-8 mode
311 .\" JOIN
312 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
313 or \fBpcre_dfa_exec()\fP
314 .\" JOIN
315 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
316 or \fBpcre_dfa_exec()\fP
317 .\" JOIN
318 \eCdd call pcre_copy_substring() for substring dd
319 after a successful match (number less than 32)
320 .\" JOIN
321 \eCname call pcre_copy_named_substring() for substring
322 "name" after a successful match (name termin-
323 ated by next non alphanumeric character)
324 .\" JOIN
325 \eC+ show the current captured substrings at callout
326 time
327 \eC- do not supply a callout function
328 .\" JOIN
329 \eC!n return 1 instead of 0 when callout number n is
330 reached
331 .\" JOIN
332 \eC!n!m return 1 instead of 0 when callout number n is
333 reached for the nth time
334 .\" JOIN
335 \eC*n pass the number n (may be negative) as callout
336 data; this is used as the callout return value
337 \eD use the \fBpcre_dfa_exec()\fP match function
338 \eF only shortest match for \fBpcre_dfa_exec()\fP
339 .\" JOIN
340 \eGdd call pcre_get_substring() for substring dd
341 after a successful match (number less than 32)
342 .\" JOIN
343 \eGname call pcre_get_named_substring() for substring
344 "name" after a successful match (name termin-
345 ated by next non-alphanumeric character)
346 .\" JOIN
347 \eL call pcre_get_substringlist() after a
348 successful match
349 .\" JOIN
350 \eM discover the minimum MATCH_LIMIT and
352 .\" JOIN
353 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
354 or \fBpcre_dfa_exec()\fP
355 .\" JOIN
356 \eOdd set the size of the output vector passed to
357 \fBpcre_exec()\fP to dd (any number of digits)
358 .\" JOIN
359 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
360 or \fBpcre_dfa_exec()\fP
361 .\" JOIN
362 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
363 (any number of digits)
364 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
365 \eS output details of memory get/free calls during matching
366 .\" JOIN
367 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
368 or \fBpcre_dfa_exec()\fP
369 .\" JOIN
370 \e? pass the PCRE_NO_UTF8_CHECK option to
371 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
372 \e>dd start the match at offset dd (any number of digits);
373 .\" JOIN
374 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
375 or \fBpcre_dfa_exec()\fP
376 .\" JOIN
377 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
378 or \fBpcre_dfa_exec()\fP
379 .\" JOIN
380 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
381 or \fBpcre_dfa_exec()\fP
382 .\" JOIN
383 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
384 or \fBpcre_dfa_exec()\fP
385 .\" JOIN
386 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
387 or \fBpcre_dfa_exec()\fP
388 .\" JOIN
389 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
390 or \fBpcre_dfa_exec()\fP
391 .sp
392 The escapes that specify line ending sequences are literal strings, exactly as
393 shown. No more than one newline setting should be present in any data line.
394 .P
395 A backslash followed by anything else just escapes the anything else. If
396 the very last character is a backslash, it is ignored. This gives a way of
397 passing an empty line as data, since a real empty line terminates the data
398 input.
399 .P
400 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
401 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
402 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
403 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
404 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
405 place, and checking it out can be instructive. For most simple matches, the
406 number is quite small, but for patterns with very large numbers of matching
407 possibilities, it can become large very quickly with increasing length of
408 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
409 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
410 to complete the match attempt.
411 .P
412 When \eO is used, the value specified may be higher or lower than the size set
413 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
414 the call of \fBpcre_exec()\fP for the line in which it appears.
415 .P
416 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
417 API to be used, the only option-setting sequences that have any effect are \eB
418 and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
419 \fBregexec()\fP.
420 .P
421 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
422 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
423 any number of hexadecimal digits inside the braces. The result is from one to
424 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
425 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
426 valid Unicode code points, or indeed valid UTF-8 characters according to the
427 later rules in RFC 3629.
428 .
429 .
431 .rs
432 .sp
433 By default, \fBpcretest\fP uses the standard PCRE matching function,
434 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
435 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
436 different way, and has some restrictions. The differences between the two
437 functions are described in the
438 .\" HREF
439 \fBpcrematching\fP
440 .\"
441 documentation.
442 .P
443 If a data line contains the \eD escape sequence, or if the command line
444 contains the \fB-dfa\fP option, the alternative matching function is called.
445 This function finds all possible matches at a given point. If, however, the \eF
446 escape sequence is present in the data line, it stops after the first match is
447 found. This is always the shortest possible match.
448 .
449 .
451 .rs
452 .sp
453 This section describes the output when the normal matching function,
454 \fBpcre_exec()\fP, is being used.
455 .P
456 When a match succeeds, pcretest outputs the list of captured substrings that
457 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
458 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
459 when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
460 respectively, and otherwise the PCRE negative error number. Here is an example
461 of an interactive \fBpcretest\fP run.
462 .sp
463 $ pcretest
464 PCRE version 7.0 30-Nov-2006
465 .sp
466 re> /^abc(\ed+)/
467 data> abc123
468 0: abc123
469 1: 123
470 data> xyz
471 No match
472 .sp
473 Note that unset capturing substrings that are not followed by one that is set
474 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
475 the following example, there are two capturing substrings, but when the first
476 data line is matched, the second, unset substring is not shown. An "internal"
477 unset substring is shown as "<unset>", as for the second data line.
478 .sp
479 re> /(a)|(b)/
480 data> a
481 0: a
482 1: a
483 data> b
484 0: b
485 1: <unset>
486 2: b
487 .sp
488 If the strings contain any non-printing characters, they are output as \e0x
489 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
490 pattern. See below for the definition of non-printing characters. If the
491 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
492 the the rest of the subject string, identified by "0+" like this:
493 .sp
494 re> /cat/+
495 data> cataract
496 0: cat
497 0+ aract
498 .sp
499 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
500 matching attempts are output in sequence, like this:
501 .sp
502 re> /\eBi(\ew\ew)/g
503 data> Mississippi
504 0: iss
505 1: ss
506 0: iss
507 1: ss
508 0: ipp
509 1: pp
510 .sp
511 "No match" is output only if the first match attempt fails.
512 .P
513 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
514 data line that is successfully matched, the substrings extracted by the
515 convenience functions are output with C, G, or L after the string number
516 instead of a colon. This is in addition to the normal full list. The string
517 length (that is, the return from the extraction function) is given in
518 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
519 .P
520 Note that whereas patterns can be continued over several lines (a plain ">"
521 prompt is used for continuations), data lines may not. However newlines can be
522 included in data by means of the \en escape (or \er, \er\en, etc., depending on
523 the newline sequence setting).
524 .
525 .
526 .
528 .rs
529 .sp
530 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
531 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
532 output consists of a list of all the matches that start at the first point in
533 the subject where there is at least one match. For example:
534 .sp
535 re> /(tang|tangerine|tan)/
536 data> yellow tangerine\eD
537 0: tangerine
538 1: tang
539 2: tan
540 .sp
541 (Using the normal matching function on this data finds only "tang".) The
542 longest matching string is always given first (and numbered zero).
543 .P
544 If \fB/g\fP is present on the pattern, the search for further matches resumes
545 at the end of the longest match. For example:
546 .sp
547 re> /(tang|tangerine|tan)/g
548 data> yellow tangerine and tangy sultana\eD
549 0: tangerine
550 1: tang
551 2: tan
552 0: tang
553 1: tan
554 0: tan
555 .sp
556 Since the matching function does not support substring capture, the escape
557 sequences that are concerned with captured substrings are not relevant.
558 .
559 .
561 .rs
562 .sp
563 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
564 indicating that the subject partially matched the pattern, you can restart the
565 match with additional subject data by means of the \eR escape sequence. For
566 example:
567 .sp
568 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
569 data> 23ja\eP\eD
570 Partial match: 23ja
571 data> n05\eR\eD
572 0: n05
573 .sp
574 For further information about partial matching, see the
575 .\" HREF
576 \fBpcrepartial\fP
577 .\"
578 documentation.
579 .
580 .
582 .rs
583 .sp
584 If the pattern contains any callout requests, \fBpcretest\fP's callout function
585 is called during matching. This works with both matching functions. By default,
586 the called function displays the callout number, the start and current
587 positions in the text at the callout time, and the next pattern item to be
588 tested. For example, the output
589 .sp
590 --->pqrabcdef
591 0 ^ ^ \ed
592 .sp
593 indicates that callout number 0 occurred for a match attempt starting at the
594 fourth character of the subject string, when the pointer was at the seventh
595 character of the data, and when the next pattern item was \ed. Just one
596 circumflex is output if the start and current positions are the same.
597 .P
598 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
599 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
600 callout number, the offset in the pattern, preceded by a plus, is output. For
601 example:
602 .sp
603 re> /\ed?[A-E]\e*/C
604 data> E*
605 --->E*
606 +0 ^ \ed?
607 +3 ^ [A-E]
608 +8 ^^ \e*
609 +10 ^ ^
610 0: E*
611 .sp
612 The callout function in \fBpcretest\fP returns zero (carry on matching) by
613 default, but you can use a \eC item in a data line (as described above) to
614 change this.
615 .P
616 Inserting callouts can be helpful when using \fBpcretest\fP to check
617 complicated regular expressions. For further information about callouts, see
618 the
619 .\" HREF
620 \fBpcrecallout\fP
621 .\"
622 documentation.
623 .
624 .
625 .
627 .rs
628 .sp
629 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
630 bytes other than 32-126 are always treated as non-printing characters are are
631 therefore shown as hex escapes.
632 .P
633 When \fBpcretest\fP is outputting text that is a matched part of a subject
634 string, it behaves in the same way, unless a different locale has been set for
635 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
636 function to distinguish printing and non-printing characters.
637 .
638 .
639 .
641 .rs
642 .sp
643 The facilities described in this section are not available when the POSIX
644 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
645 specified.
646 .P
647 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
648 compiled pattern to a file, by following the modifiers with > and a file name.
649 For example:
650 .sp
651 /pattern/im >/some/file
652 .sp
653 See the
654 .\" HREF
655 \fBpcreprecompile\fP
656 .\"
657 documentation for a discussion about saving and re-using compiled patterns.
658 .P
659 The data that is written is binary. The first eight bytes are the length of the
660 compiled pattern data followed by the length of the optional study data, each
661 written as four bytes in big-endian order (most significant byte first). If
662 there is no study data (either the pattern was not studied, or studying did not
663 return any data), the second length is zero. The lengths are followed by an
664 exact copy of the compiled pattern. If there is additional study data, this
665 follows immediately after the compiled pattern. After writing the file,
666 \fBpcretest\fP expects to read a new pattern.
667 .P
668 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
669 name instead of a pattern. The name of the file must not contain a < character,
670 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
671 characters.
672 For example:
673 .sp
674 re> </some/file
675 Compiled regex loaded from /some/file
676 No study data
677 .sp
678 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
679 the usual way.
680 .P
681 You can copy a file written by \fBpcretest\fP to a different host and reload it
682 there, even if the new host has opposite endianness to the one on which the
683 pattern was compiled. For example, you can compile on an i86 machine and run on
684 a SPARC machine.
685 .P
686 File names for saving and reloading can be absolute or relative, but note that
687 the shell facility of expanding a file name that starts with a tilde (~) is not
688 available.
689 .P
690 The ability to save and reload files in \fBpcretest\fP is intended for testing
691 and experimentation. It is not intended for production use because only a
692 single pattern can be written to a file. Furthermore, there is no facility for
693 supplying custom character tables for use with a reloaded pattern. If the
694 original pattern was compiled with custom tables, an attempt to match a subject
695 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
696 Finally, if you attempt to load a file that is not in the correct format, the
697 result is undefined.
698 .
699 .
700 .SH "SEE ALSO"
701 .rs
702 .sp
703 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
704 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
705 .
706 .
708 .rs
709 .sp
710 .nf
711 Philip Hazel
712 University Computing Service
713 Cambridge CB2 3QH, England.
714 .fi
715 .
716 .
718 .rs
719 .sp
720 .nf
721 Last updated: 12 April 2008
722 Copyright (c) 1997-2008 University of Cambridge.
723 .fi


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