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1 .TH PCRETEST 1
2 .SH NAME
3 pcretest - a program for testing Perl-compatible regular expressions.
4 .SH SYNOPSIS
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 .
24 .SH OPTIONS
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 .
91 .SH DESCRIPTION
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 The program handles any number of sets of input on a single input file. Each
101 set starts with a regular expression, and continues with any number of data
102 lines to be matched against the pattern.
103 .P
104 Each data line is matched separately and independently. If you want to do
105 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
106 etc., depending on the newline setting) in a single line of input to encode the
107 newline sequences. There is no limit on the length of data lines; the input
108 buffer is automatically extended if it is too small.
109 .P
110 An empty line signals the end of the data lines, at which point a new regular
111 expression is read. The regular expressions are given enclosed in any
112 non-alphanumeric delimiters other than backslash, for example:
113 .sp
114 /(a|bc)x+yz/
115 .sp
116 White space before the initial delimiter is ignored. A regular expression may
117 be continued over several input lines, in which case the newline characters are
118 included within it. It is possible to include the delimiter within the pattern
119 by escaping it, for example
120 .sp
121 /abc\e/def/
122 .sp
123 If you do so, the escape and the delimiter form part of the pattern, but since
124 delimiters are always non-alphanumeric, this does not affect its interpretation.
125 If the terminating delimiter is immediately followed by a backslash, for
126 example,
127 .sp
128 /abc/\e
129 .sp
130 then a backslash is added to the end of the pattern. This is done to provide a
131 way of testing the error condition that arises if a pattern finishes with a
132 backslash, because
133 .sp
134 /abc\e/
135 .sp
136 is interpreted as the first line of a pattern that starts with "abc/", causing
137 pcretest to read the next line as a continuation of the regular expression.
138 .
139 .
140 .SH "PATTERN MODIFIERS"
141 .rs
142 .sp
143 A pattern may be followed by any number of modifiers, which are mostly single
144 characters. Following Perl usage, these are referred to below as, for example,
145 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
146 always be a slash, and no slash is used when writing modifiers. Whitespace may
147 appear between the final pattern delimiter and the first modifier, and between
148 the modifiers themselves.
149 .P
150 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
151 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
152 \fBpcre_compile()\fP is called. These four modifier letters have the same
153 effect as they do in Perl. For example:
154 .sp
155 /caseless/i
156 .sp
157 The following table shows additional modifiers for setting PCRE options that do
158 not correspond to anything in Perl:
159 .sp
160 \fB/A\fP PCRE_ANCHORED
161 \fB/C\fP PCRE_AUTO_CALLOUT
162 \fB/E\fP PCRE_DOLLAR_ENDONLY
163 \fB/f\fP PCRE_FIRSTLINE
164 \fB/J\fP PCRE_DUPNAMES
165 \fB/N\fP PCRE_NO_AUTO_CAPTURE
166 \fB/U\fP PCRE_UNGREEDY
167 \fB/X\fP PCRE_EXTRA
168 \fB/<cr>\fP PCRE_NEWLINE_CR
169 \fB/<lf>\fP PCRE_NEWLINE_LF
170 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
171 \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
172 \fB/<any>\fP PCRE_NEWLINE_ANY
173 .sp
174 Those specifying line ending sequences are literal strings as shown, but the
175 letters can be in either case. This example sets multiline matching with CRLF
176 as the line ending sequence:
177 .sp
178 /^abc/m<crlf>
179 .sp
180 Details of the meanings of these PCRE options are given in the
181 .\" HREF
182 \fBpcreapi\fP
183 .\"
184 documentation.
185 .
186 .
187 .SS "Finding all matches in a string"
188 .rs
189 .sp
190 Searching for all possible matches within each subject string can be requested
191 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
192 again to search the remainder of the subject string. The difference between
193 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
194 \fBpcre_exec()\fP to start searching at a new point within the entire string
195 (which is in effect what Perl does), whereas the latter passes over a shortened
196 substring. This makes a difference to the matching process if the pattern
197 begins with a lookbehind assertion (including \eb or \eB).
198 .P
199 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
200 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
201 flags set in order to search for another, non-empty, match at the same point.
202 If this second match fails, the start offset is advanced by one, and the normal
203 match is retried. This imitates the way Perl handles such cases when using the
204 \fB/g\fP modifier or the \fBsplit()\fP function.
205 .
206 .
207 .SS "Other modifiers"
208 .rs
209 .sp
210 There are yet more modifiers for controlling the way \fBpcretest\fP
211 operates.
212 .P
213 The \fB/+\fP modifier requests that as well as outputting the substring that
214 matched the entire pattern, pcretest should in addition output the remainder of
215 the subject string. This is useful for tests where the subject contains
216 multiple copies of the same substring.
217 .P
218 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
219 output a representation of the compiled byte code after compilation. Normally
220 this information contains length and offset values; however, if \fB/Z\fP is
221 also present, this data is replaced by spaces. This is a special feature for
222 use in the automatic test scripts; it ensures that the same output is generated
223 for different internal link sizes.
224 .P
225 The \fB/L\fP modifier must be followed directly by the name of a locale, for
226 example,
227 .sp
228 /pattern/Lfr_FR
229 .sp
230 For this reason, it must be the last modifier. The given locale is set,
231 \fBpcre_maketables()\fP is called to build a set of character tables for the
232 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
233 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
234 pointer; that is, \fB/L\fP applies only to the expression on which it appears.
235 .P
236 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
237 compiled pattern (whether it is anchored, has a fixed first character, and
238 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
239 pattern. If the pattern is studied, the results of that are also output.
240 .P
241 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
242 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
243 .P
244 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
245 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
246 facility is for testing the feature in PCRE that allows it to execute patterns
247 that were compiled on a host with a different endianness. This feature is not
248 available when the POSIX interface to PCRE is being used, that is, when the
249 \fB/P\fP pattern modifier is specified. See also the section about saving and
250 reloading compiled patterns below.
251 .P
252 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
253 expression has been compiled, and the results used when the expression is
254 matched.
255 .P
256 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
257 pattern to be output.
258 .P
259 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
260 API rather than its native API. When this is done, all other modifiers except
261 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
262 present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
263 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
264 .P
265 The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
266 option set. This turns on support for UTF-8 character handling in PCRE,
267 provided that it was compiled with this support enabled. This modifier also
268 causes any non-printing characters in output strings to be printed using the
269 \ex{hh...} notation if they are valid UTF-8 sequences.
270 .P
271 If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
272 call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
273 checking of the string for UTF-8 validity.
274 .
275 .
276 .SH "DATA LINES"
277 .rs
278 .sp
279 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
280 whitespace is removed, and it is then scanned for \e escapes. Some of these are
281 pretty esoteric features, intended for checking out some of the more
282 complicated features of PCRE. If you are just testing "ordinary" regular
283 expressions, you probably don't need any of these. The following escapes are
284 recognized:
285 .sp
286 \ea alarm (BEL, \ex07)
287 \eb backspace (\ex08)
288 \ee escape (\ex27)
289 \ef formfeed (\ex0c)
290 \en newline (\ex0a)
291 .\" JOIN
292 \eqdd set the PCRE_MATCH_LIMIT limit to dd
293 (any number of digits)
294 \er carriage return (\ex0d)
295 \et tab (\ex09)
296 \ev vertical tab (\ex0b)
297 \ennn octal character (up to 3 octal digits)
298 \exhh hexadecimal character (up to 2 hex digits)
299 .\" JOIN
300 \ex{hh...} hexadecimal character, any number of digits
301 in UTF-8 mode
302 .\" JOIN
303 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
304 or \fBpcre_dfa_exec()\fP
305 .\" JOIN
306 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
307 or \fBpcre_dfa_exec()\fP
308 .\" JOIN
309 \eCdd call pcre_copy_substring() for substring dd
310 after a successful match (number less than 32)
311 .\" JOIN
312 \eCname call pcre_copy_named_substring() for substring
313 "name" after a successful match (name termin-
314 ated by next non alphanumeric character)
315 .\" JOIN
316 \eC+ show the current captured substrings at callout
317 time
318 \eC- do not supply a callout function
319 .\" JOIN
320 \eC!n return 1 instead of 0 when callout number n is
321 reached
322 .\" JOIN
323 \eC!n!m return 1 instead of 0 when callout number n is
324 reached for the nth time
325 .\" JOIN
326 \eC*n pass the number n (may be negative) as callout
327 data; this is used as the callout return value
328 \eD use the \fBpcre_dfa_exec()\fP match function
329 \eF only shortest match for \fBpcre_dfa_exec()\fP
330 .\" JOIN
331 \eGdd call pcre_get_substring() for substring dd
332 after a successful match (number less than 32)
333 .\" JOIN
334 \eGname call pcre_get_named_substring() for substring
335 "name" after a successful match (name termin-
336 ated by next non-alphanumeric character)
337 .\" JOIN
338 \eL call pcre_get_substringlist() after a
339 successful match
340 .\" JOIN
341 \eM discover the minimum MATCH_LIMIT and
342 MATCH_LIMIT_RECURSION settings
343 .\" JOIN
344 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
345 or \fBpcre_dfa_exec()\fP
346 .\" JOIN
347 \eOdd set the size of the output vector passed to
348 \fBpcre_exec()\fP to dd (any number of digits)
349 .\" JOIN
350 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
351 or \fBpcre_dfa_exec()\fP
352 .\" JOIN
353 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
354 (any number of digits)
355 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
356 \eS output details of memory get/free calls during matching
357 .\" JOIN
358 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
359 or \fBpcre_dfa_exec()\fP
360 .\" JOIN
361 \e? pass the PCRE_NO_UTF8_CHECK option to
362 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
363 \e>dd start the match at offset dd (any number of digits);
364 .\" JOIN
365 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
366 or \fBpcre_dfa_exec()\fP
367 .\" JOIN
368 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
369 or \fBpcre_dfa_exec()\fP
370 .\" JOIN
371 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
372 or \fBpcre_dfa_exec()\fP
373 .\" JOIN
374 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
375 or \fBpcre_dfa_exec()\fP
376 .\" JOIN
377 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
378 or \fBpcre_dfa_exec()\fP
379 .\" JOIN
380 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
381 or \fBpcre_dfa_exec()\fP
382 .sp
383 The escapes that specify line ending sequences are literal strings, exactly as
384 shown. No more than one newline setting should be present in any data line.
385 .P
386 A backslash followed by anything else just escapes the anything else. If
387 the very last character is a backslash, it is ignored. This gives a way of
388 passing an empty line as data, since a real empty line terminates the data
389 input.
390 .P
391 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
392 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
393 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
394 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
395 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
396 place, and checking it out can be instructive. For most simple matches, the
397 number is quite small, but for patterns with very large numbers of matching
398 possibilities, it can become large very quickly with increasing length of
399 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
400 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
401 to complete the match attempt.
402 .P
403 When \eO is used, the value specified may be higher or lower than the size set
404 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
405 the call of \fBpcre_exec()\fP for the line in which it appears.
406 .P
407 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
408 API to be used, the only option-setting sequences that have any effect are \eB
409 and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
410 \fBregexec()\fP.
411 .P
412 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
413 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
414 any number of hexadecimal digits inside the braces. The result is from one to
415 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
416 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
417 valid Unicode code points, or indeed valid UTF-8 characters according to the
418 later rules in RFC 3629.
419 .
420 .
421 .SH "THE ALTERNATIVE MATCHING FUNCTION"
422 .rs
423 .sp
424 By default, \fBpcretest\fP uses the standard PCRE matching function,
425 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
426 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
427 different way, and has some restrictions. The differences between the two
428 functions are described in the
429 .\" HREF
430 \fBpcrematching\fP
431 .\"
432 documentation.
433 .P
434 If a data line contains the \eD escape sequence, or if the command line
435 contains the \fB-dfa\fP option, the alternative matching function is called.
436 This function finds all possible matches at a given point. If, however, the \eF
437 escape sequence is present in the data line, it stops after the first match is
438 found. This is always the shortest possible match.
439 .
440 .
441 .SH "DEFAULT OUTPUT FROM PCRETEST"
442 .rs
443 .sp
444 This section describes the output when the normal matching function,
445 \fBpcre_exec()\fP, is being used.
446 .P
447 When a match succeeds, pcretest outputs the list of captured substrings that
448 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
449 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
450 when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
451 respectively, and otherwise the PCRE negative error number. Here is an example
452 of an interactive \fBpcretest\fP run.
453 .sp
454 $ pcretest
455 PCRE version 7.0 30-Nov-2006
456 .sp
457 re> /^abc(\ed+)/
458 data> abc123
459 0: abc123
460 1: 123
461 data> xyz
462 No match
463 .sp
464 If the strings contain any non-printing characters, they are output as \e0x
465 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
466 pattern. See below for the definition of non-printing characters. If the
467 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
468 the the rest of the subject string, identified by "0+" like this:
469 .sp
470 re> /cat/+
471 data> cataract
472 0: cat
473 0+ aract
474 .sp
475 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
476 matching attempts are output in sequence, like this:
477 .sp
478 re> /\eBi(\ew\ew)/g
479 data> Mississippi
480 0: iss
481 1: ss
482 0: iss
483 1: ss
484 0: ipp
485 1: pp
486 .sp
487 "No match" is output only if the first match attempt fails.
488 .P
489 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
490 data line that is successfully matched, the substrings extracted by the
491 convenience functions are output with C, G, or L after the string number
492 instead of a colon. This is in addition to the normal full list. The string
493 length (that is, the return from the extraction function) is given in
494 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
495 .P
496 Note that whereas patterns can be continued over several lines (a plain ">"
497 prompt is used for continuations), data lines may not. However newlines can be
498 included in data by means of the \en escape (or \er, \er\en, etc., depending on
499 the newline sequence setting).
500 .
501 .
502 .
503 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
504 .rs
505 .sp
506 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
507 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
508 output consists of a list of all the matches that start at the first point in
509 the subject where there is at least one match. For example:
510 .sp
511 re> /(tang|tangerine|tan)/
512 data> yellow tangerine\eD
513 0: tangerine
514 1: tang
515 2: tan
516 .sp
517 (Using the normal matching function on this data finds only "tang".) The
518 longest matching string is always given first (and numbered zero).
519 .P
520 If \fB/g\fP is present on the pattern, the search for further matches resumes
521 at the end of the longest match. For example:
522 .sp
523 re> /(tang|tangerine|tan)/g
524 data> yellow tangerine and tangy sultana\eD
525 0: tangerine
526 1: tang
527 2: tan
528 0: tang
529 1: tan
530 0: tan
531 .sp
532 Since the matching function does not support substring capture, the escape
533 sequences that are concerned with captured substrings are not relevant.
534 .
535 .
536 .SH "RESTARTING AFTER A PARTIAL MATCH"
537 .rs
538 .sp
539 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
540 indicating that the subject partially matched the pattern, you can restart the
541 match with additional subject data by means of the \eR escape sequence. For
542 example:
543 .sp
544 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
545 data> 23ja\eP\eD
546 Partial match: 23ja
547 data> n05\eR\eD
548 0: n05
549 .sp
550 For further information about partial matching, see the
551 .\" HREF
552 \fBpcrepartial\fP
553 .\"
554 documentation.
555 .
556 .
557 .SH CALLOUTS
558 .rs
559 .sp
560 If the pattern contains any callout requests, \fBpcretest\fP's callout function
561 is called during matching. This works with both matching functions. By default,
562 the called function displays the callout number, the start and current
563 positions in the text at the callout time, and the next pattern item to be
564 tested. For example, the output
565 .sp
566 --->pqrabcdef
567 0 ^ ^ \ed
568 .sp
569 indicates that callout number 0 occurred for a match attempt starting at the
570 fourth character of the subject string, when the pointer was at the seventh
571 character of the data, and when the next pattern item was \ed. Just one
572 circumflex is output if the start and current positions are the same.
573 .P
574 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
575 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
576 callout number, the offset in the pattern, preceded by a plus, is output. For
577 example:
578 .sp
579 re> /\ed?[A-E]\e*/C
580 data> E*
581 --->E*
582 +0 ^ \ed?
583 +3 ^ [A-E]
584 +8 ^^ \e*
585 +10 ^ ^
586 0: E*
587 .sp
588 The callout function in \fBpcretest\fP returns zero (carry on matching) by
589 default, but you can use a \eC item in a data line (as described above) to
590 change this.
591 .P
592 Inserting callouts can be helpful when using \fBpcretest\fP to check
593 complicated regular expressions. For further information about callouts, see
594 the
595 .\" HREF
596 \fBpcrecallout\fP
597 .\"
598 documentation.
599 .
600 .
601 .
602 .SH "NON-PRINTING CHARACTERS"
603 .rs
604 .sp
605 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
606 bytes other than 32-126 are always treated as non-printing characters are are
607 therefore shown as hex escapes.
608 .P
609 When \fBpcretest\fP is outputting text that is a matched part of a subject
610 string, it behaves in the same way, unless a different locale has been set for
611 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
612 function to distinguish printing and non-printing characters.
613 .
614 .
615 .
616 .SH "SAVING AND RELOADING COMPILED PATTERNS"
617 .rs
618 .sp
619 The facilities described in this section are not available when the POSIX
620 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
621 specified.
622 .P
623 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
624 compiled pattern to a file, by following the modifiers with > and a file name.
625 For example:
626 .sp
627 /pattern/im >/some/file
628 .sp
629 See the
630 .\" HREF
631 \fBpcreprecompile\fP
632 .\"
633 documentation for a discussion about saving and re-using compiled patterns.
634 .P
635 The data that is written is binary. The first eight bytes are the length of the
636 compiled pattern data followed by the length of the optional study data, each
637 written as four bytes in big-endian order (most significant byte first). If
638 there is no study data (either the pattern was not studied, or studying did not
639 return any data), the second length is zero. The lengths are followed by an
640 exact copy of the compiled pattern. If there is additional study data, this
641 follows immediately after the compiled pattern. After writing the file,
642 \fBpcretest\fP expects to read a new pattern.
643 .P
644 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
645 name instead of a pattern. The name of the file must not contain a < character,
646 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
647 characters.
648 For example:
649 .sp
650 re> </some/file
651 Compiled regex loaded from /some/file
652 No study data
653 .sp
654 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
655 the usual way.
656 .P
657 You can copy a file written by \fBpcretest\fP to a different host and reload it
658 there, even if the new host has opposite endianness to the one on which the
659 pattern was compiled. For example, you can compile on an i86 machine and run on
660 a SPARC machine.
661 .P
662 File names for saving and reloading can be absolute or relative, but note that
663 the shell facility of expanding a file name that starts with a tilde (~) is not
664 available.
665 .P
666 The ability to save and reload files in \fBpcretest\fP is intended for testing
667 and experimentation. It is not intended for production use because only a
668 single pattern can be written to a file. Furthermore, there is no facility for
669 supplying custom character tables for use with a reloaded pattern. If the
670 original pattern was compiled with custom tables, an attempt to match a subject
671 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
672 Finally, if you attempt to load a file that is not in the correct format, the
673 result is undefined.
674 .
675 .
676 .SH "SEE ALSO"
677 .rs
678 .sp
679 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
680 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
681 .
682 .
683 .SH AUTHOR
684 .rs
685 .sp
686 .nf
687 Philip Hazel
688 University Computing Service
689 Cambridge CB2 3QH, England.
690 .fi
691 .
692 .
693 .SH REVISION
694 .rs
695 .sp
696 .nf
697 Last updated: 21 August 2007
698 Copyright (c) 1997-2007 University of Cambridge.
699 .fi

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