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1 <html>
2 <head>
3 <title>pcretest specification</title>
4 </head>
5 <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6 <h1>pcretest man page</h1>
7 <p>
8 Return to the <a href="index.html">PCRE index page</a>.
9 </p>
10 <p>
11 This page is part of the PCRE HTML documentation. It was generated automatically
12 from the original man page. If there is any nonsense in it, please consult the
13 man page, in case the conversion went wrong.
14 <br>
15 <ul>
16 <li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
17 <li><a name="TOC2" href="#SEC2">OPTIONS</a>
18 <li><a name="TOC3" href="#SEC3">DESCRIPTION</a>
19 <li><a name="TOC4" href="#SEC4">PATTERN MODIFIERS</a>
20 <li><a name="TOC5" href="#SEC5">DATA LINES</a>
21 <li><a name="TOC6" href="#SEC6">THE ALTERNATIVE MATCHING FUNCTION</a>
22 <li><a name="TOC7" href="#SEC7">DEFAULT OUTPUT FROM PCRETEST</a>
23 <li><a name="TOC8" href="#SEC8">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
24 <li><a name="TOC9" href="#SEC9">RESTARTING AFTER A PARTIAL MATCH</a>
25 <li><a name="TOC10" href="#SEC10">CALLOUTS</a>
26 <li><a name="TOC11" href="#SEC11">SAVING AND RELOADING COMPILED PATTERNS</a>
27 <li><a name="TOC12" href="#SEC12">AUTHOR</a>
28 </ul>
29 <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
30 <P>
31 <b>pcretest [options] [source] [destination]</b>
32 <br>
33 <br>
34 <b>pcretest</b> was written as a test program for the PCRE regular expression
35 library itself, but it can also be used for experimenting with regular
36 expressions. This document describes the features of the test program; for
37 details of the regular expressions themselves, see the
38 <a href="pcrepattern.html"><b>pcrepattern</b></a>
39 documentation. For details of the PCRE library function calls and their
40 options, see the
41 <a href="pcreapi.html"><b>pcreapi</b></a>
42 documentation.
43 </P>
44 <br><a name="SEC2" href="#TOC1">OPTIONS</a><br>
45 <P>
46 <b>-C</b>
47 Output the version number of the PCRE library, and all available information
48 about the optional features that are included, and then exit.
49 </P>
50 <P>
51 <b>-d</b>
52 Behave as if each regex has the <b>/D</b> (debug) modifier; the internal
53 form is output after compilation.
54 </P>
55 <P>
56 <b>-dfa</b>
57 Behave as if each data line contains the \D escape sequence; this causes the
58 alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the
59 standard <b>pcre_exec()</b> function (more detail is given below).
60 </P>
61 <P>
62 <b>-i</b>
63 Behave as if each regex has the <b>/I</b> modifier; information about the
64 compiled pattern is given after compilation.
65 </P>
66 <P>
67 <b>-m</b>
68 Output the size of each compiled pattern after it has been compiled. This is
69 equivalent to adding <b>/M</b> to each regular expression. For compatibility
70 with earlier versions of pcretest, <b>-s</b> is a synonym for <b>-m</b>.
71 </P>
72 <P>
73 <b>-o</b> <i>osize</i>
74 Set the number of elements in the output vector that is used when calling
75 <b>pcre_exec()</b> to be <i>osize</i>. The default value is 45, which is enough
76 for 14 capturing subexpressions. The vector size can be changed for individual
77 matching calls by including \O in the data line (see below).
78 </P>
79 <P>
80 <b>-p</b>
81 Behave as if each regex has the <b>/P</b> modifier; the POSIX wrapper API is
82 used to call PCRE. None of the other options has any effect when <b>-p</b> is
83 set.
84 </P>
85 <P>
86 <b>-q</b>
87 Do not output the version number of <b>pcretest</b> at the start of execution.
88 </P>
89 <P>
90 <b>-S</b> <i>size</i>
91 On Unix-like systems, set the size of the runtime stack to <i>size</i>
92 megabytes.
93 </P>
94 <P>
95 <b>-t</b>
96 Run each compile, study, and match many times with a timer, and output
97 resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with
98 <b>-t</b>, because you will then get the size output a zillion times, and the
99 timing will be distorted.
100 </P>
101 <br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
102 <P>
103 If <b>pcretest</b> is given two filename arguments, it reads from the first and
104 writes to the second. If it is given only one filename argument, it reads from
105 that file and writes to stdout. Otherwise, it reads from stdin and writes to
106 stdout, and prompts for each line of input, using "re&#62;" to prompt for regular
107 expressions, and "data&#62;" to prompt for data lines.
108 </P>
109 <P>
110 The program handles any number of sets of input on a single input file. Each
111 set starts with a regular expression, and continues with any number of data
112 lines to be matched against the pattern.
113 </P>
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 \n escape sequence (or \r or \r\n,
117 depending on the newline setting) in a single line of input to encode the
118 newline characters. 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 <P>
122 An empty line signals the end of the data lines, at which point a new regular
123 expression is read. The regular expressions are given enclosed in any
124 non-alphanumeric delimiters other than backslash, for example:
125 <pre>
126 /(a|bc)x+yz/
127 </pre>
128 White space before the initial delimiter is ignored. A regular expression may
129 be continued over several input lines, in which case the newline characters are
130 included within it. It is possible to include the delimiter within the pattern
131 by escaping it, for example
132 <pre>
133 /abc\/def/
134 </pre>
135 If you do so, the escape and the delimiter form part of the pattern, but since
136 delimiters are always non-alphanumeric, this does not affect its interpretation.
137 If the terminating delimiter is immediately followed by a backslash, for
138 example,
139 <pre>
140 /abc/\
141 </pre>
142 then a backslash is added to the end of the pattern. This is done to provide a
143 way of testing the error condition that arises if a pattern finishes with a
144 backslash, because
145 <pre>
146 /abc\/
147 </pre>
148 is interpreted as the first line of a pattern that starts with "abc/", causing
149 pcretest to read the next line as a continuation of the regular expression.
150 </P>
151 <br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
152 <P>
153 A pattern may be followed by any number of modifiers, which are mostly single
154 characters. Following Perl usage, these are referred to below as, for example,
155 "the <b>/i</b> modifier", even though the delimiter of the pattern need not
156 always be a slash, and no slash is used when writing modifiers. Whitespace may
157 appear between the final pattern delimiter and the first modifier, and between
158 the modifiers themselves.
159 </P>
160 <P>
161 The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
162 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
163 <b>pcre_compile()</b> is called. These four modifier letters have the same
164 effect as they do in Perl. For example:
165 <pre>
166 /caseless/i
167 </pre>
168 The following table shows additional modifiers for setting PCRE options that do
169 not correspond to anything in Perl:
170 <pre>
171 <b>/A</b> PCRE_ANCHORED
172 <b>/C</b> PCRE_AUTO_CALLOUT
173 <b>/E</b> PCRE_DOLLAR_ENDONLY
174 <b>/f</b> PCRE_FIRSTLINE
175 <b>/J</b> PCRE_DUPNAMES
176 <b>/N</b> PCRE_NO_AUTO_CAPTURE
177 <b>/U</b> PCRE_UNGREEDY
178 <b>/X</b> PCRE_EXTRA
179 <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
180 <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
181 <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
182 </pre>
183 Those specifying line endings are literal strings as shown. Details of the
184 meanings of these PCRE options are given in the
185 <a href="pcreapi.html"><b>pcreapi</b></a>
186 documentation.
187 </P>
188 <br><b>
189 Finding all matches in a string
190 </b><br>
191 <P>
192 Searching for all possible matches within each subject string can be requested
193 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
194 again to search the remainder of the subject string. The difference between
195 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
196 <b>pcre_exec()</b> to start searching at a new point within the entire string
197 (which is in effect what Perl does), whereas the latter passes over a shortened
198 substring. This makes a difference to the matching process if the pattern
199 begins with a lookbehind assertion (including \b or \B).
200 </P>
201 <P>
202 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
203 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
204 flags set in order to search for another, non-empty, match at the same point.
205 If this second match fails, the start offset is advanced by one, and the normal
206 match is retried. This imitates the way Perl handles such cases when using the
207 <b>/g</b> modifier or the <b>split()</b> function.
208 </P>
209 <br><b>
210 Other modifiers
211 </b><br>
212 <P>
213 There are yet more modifiers for controlling the way <b>pcretest</b>
214 operates.
215 </P>
216 <P>
217 The <b>/+</b> modifier requests that as well as outputting the substring that
218 matched the entire pattern, pcretest should in addition output the remainder of
219 the subject string. This is useful for tests where the subject contains
220 multiple copies of the same substring.
221 </P>
222 <P>
223 The <b>/L</b> modifier must be followed directly by the name of a locale, for
224 example,
225 <pre>
226 /pattern/Lfr_FR
227 </pre>
228 For this reason, it must be the last modifier. The given locale is set,
229 <b>pcre_maketables()</b> is called to build a set of character tables for the
230 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
231 regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
232 pointer; that is, <b>/L</b> applies only to the expression on which it appears.
233 </P>
234 <P>
235 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
236 compiled pattern (whether it is anchored, has a fixed first character, and
237 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
238 pattern. If the pattern is studied, the results of that are also output.
239 </P>
240 <P>
241 The <b>/D</b> modifier is a PCRE debugging feature, which also assumes <b>/I</b>.
242 It causes the internal form of compiled regular expressions to be output after
243 compilation. If the pattern was studied, the information returned is also
244 output.
245 </P>
246 <P>
247 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
248 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
249 facility is for testing the feature in PCRE that allows it to execute patterns
250 that were compiled on a host with a different endianness. This feature is not
251 available when the POSIX interface to PCRE is being used, that is, when the
252 <b>/P</b> pattern modifier is specified. See also the section about saving and
253 reloading compiled patterns below.
254 </P>
255 <P>
256 The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
257 expression has been compiled, and the results used when the expression is
258 matched.
259 </P>
260 <P>
261 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
262 pattern to be output.
263 </P>
264 <P>
265 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
266 API rather than its native API. When this is done, all other modifiers except
267 <b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
268 present, and REG_NEWLINE is set if <b>/m</b> is present. The wrapper functions
269 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
270 </P>
271 <P>
272 The <b>/8</b> modifier causes <b>pcretest</b> to call PCRE with the PCRE_UTF8
273 option set. This turns on support for UTF-8 character handling in PCRE,
274 provided that it was compiled with this support enabled. This modifier also
275 causes any non-printing characters in output strings to be printed using the
276 \x{hh...} notation if they are valid UTF-8 sequences.
277 </P>
278 <P>
279 If the <b>/?</b> modifier is used with <b>/8</b>, it causes <b>pcretest</b> to
280 call <b>pcre_compile()</b> with the PCRE_NO_UTF8_CHECK option, to suppress the
281 checking of the string for UTF-8 validity.
282 </P>
283 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
284 <P>
285 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
286 whitespace is removed, and it is then scanned for \ escapes. Some of these are
287 pretty esoteric features, intended for checking out some of the more
288 complicated features of PCRE. If you are just testing "ordinary" regular
289 expressions, you probably don't need any of these. The following escapes are
290 recognized:
291 <pre>
292 \a alarm (= BEL)
293 \b backspace
294 \e escape
295 \f formfeed
296 \n newline
297 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
298 \r carriage return
299 \t tab
300 \v vertical tab
301 \nnn octal character (up to 3 octal digits)
302 \xhh hexadecimal character (up to 2 hex digits)
303 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
304 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
305 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
306 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
307 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
308 ated by next non alphanumeric character)
309 \C+ show the current captured substrings at callout time
310 \C- do not supply a callout function
311 \C!n return 1 instead of 0 when callout number n is reached
312 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
313 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
314 \D use the <b>pcre_dfa_exec()</b> match function
315 \F only shortest match for <b>pcre_dfa_exec()</b>
316 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
317 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
318 ated by next non-alphanumeric character)
319 \L call pcre_get_substringlist() after a successful match
320 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
321 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
322 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
323 \P pass the PCRE_PARTIAL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
324 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
325 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
326 \S output details of memory get/free calls during matching
327 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
328 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
329 \&#62;dd start the match at offset dd (any number of digits);
330 this sets the <i>startoffset</i> argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
331 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
332 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
333 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
334 </pre>
335 The escapes that specify line endings are literal strings, exactly as shown.
336 A backslash followed by anything else just escapes the anything else. If the
337 very last character is a backslash, it is ignored. This gives a way of passing
338 an empty line as data, since a real empty line terminates the data input.
339 </P>
340 <P>
341 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
342 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
343 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
344 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
345 <i>match_limit</i> number is a measure of the amount of backtracking that takes
346 place, and checking it out can be instructive. For most simple matches, the
347 number is quite small, but for patterns with very large numbers of matching
348 possibilities, it can become large very quickly with increasing length of
349 subject string. The <i>match_limit_recursion</i> number is a measure of how much
350 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
351 to complete the match attempt.
352 </P>
353 <P>
354 When \O is used, the value specified may be higher or lower than the size set
355 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
356 the call of <b>pcre_exec()</b> for the line in which it appears.
357 </P>
358 <P>
359 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
360 API to be used, the only option-setting sequences that have any effect are \B
361 and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
362 <b>regexec()</b>.
363 </P>
364 <P>
365 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
366 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
367 any number of hexadecimal digits inside the braces. The result is from one to
368 six bytes, encoded according to the UTF-8 rules.
369 </P>
370 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
371 <P>
372 By default, <b>pcretest</b> uses the standard PCRE matching function,
373 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
374 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
375 different way, and has some restrictions. The differences between the two
376 functions are described in the
377 <a href="pcrematching.html"><b>pcrematching</b></a>
378 documentation.
379 </P>
380 <P>
381 If a data line contains the \D escape sequence, or if the command line
382 contains the <b>-dfa</b> option, the alternative matching function is called.
383 This function finds all possible matches at a given point. If, however, the \F
384 escape sequence is present in the data line, it stops after the first match is
385 found. This is always the shortest possible match.
386 </P>
387 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
388 <P>
389 This section describes the output when the normal matching function,
390 <b>pcre_exec()</b>, is being used.
391 </P>
392 <P>
393 When a match succeeds, pcretest outputs the list of captured substrings that
394 <b>pcre_exec()</b> returns, starting with number 0 for the string that matched
395 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
396 when <b>pcre_exec()</b> returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
397 respectively, and otherwise the PCRE negative error number. Here is an example
398 of an interactive <b>pcretest</b> run.
399 <pre>
400 $ pcretest
401 PCRE version 5.00 07-Sep-2004
402
403 re&#62; /^abc(\d+)/
404 data&#62; abc123
405 0: abc123
406 1: 123
407 data&#62; xyz
408 No match
409 </pre>
410 If the strings contain any non-printing characters, they are output as \0x
411 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
412 pattern. If the pattern has the <b>/+</b> modifier, the output for substring 0
413 is followed by the the rest of the subject string, identified by "0+" like
414 this:
415 <pre>
416 re&#62; /cat/+
417 data&#62; cataract
418 0: cat
419 0+ aract
420 </pre>
421 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
422 matching attempts are output in sequence, like this:
423 <pre>
424 re&#62; /\Bi(\w\w)/g
425 data&#62; Mississippi
426 0: iss
427 1: ss
428 0: iss
429 1: ss
430 0: ipp
431 1: pp
432 </pre>
433 "No match" is output only if the first match attempt fails.
434 </P>
435 <P>
436 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
437 data line that is successfully matched, the substrings extracted by the
438 convenience functions are output with C, G, or L after the string number
439 instead of a colon. This is in addition to the normal full list. The string
440 length (that is, the return from the extraction function) is given in
441 parentheses after each string for <b>\C</b> and <b>\G</b>.
442 </P>
443 <P>
444 Note that while patterns can be continued over several lines (a plain "&#62;"
445 prompt is used for continuations), data lines may not. However newlines can be
446 included in data by means of the \n escape (or \r or \r\n for those newline
447 settings).
448 </P>
449 <br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
450 <P>
451 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
452 means of the \D escape sequence or the <b>-dfa</b> command line option), the
453 output consists of a list of all the matches that start at the first point in
454 the subject where there is at least one match. For example:
455 <pre>
456 re&#62; /(tang|tangerine|tan)/
457 data&#62; yellow tangerine\D
458 0: tangerine
459 1: tang
460 2: tan
461 </pre>
462 (Using the normal matching function on this data finds only "tang".) The
463 longest matching string is always given first (and numbered zero).
464 </P>
465 <P>
466 If \fB/g\P is present on the pattern, the search for further matches resumes
467 at the end of the longest match. For example:
468 <pre>
469 re&#62; /(tang|tangerine|tan)/g
470 data&#62; yellow tangerine and tangy sultana\D
471 0: tangerine
472 1: tang
473 2: tan
474 0: tang
475 1: tan
476 0: tan
477 </pre>
478 Since the matching function does not support substring capture, the escape
479 sequences that are concerned with captured substrings are not relevant.
480 </P>
481 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
482 <P>
483 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
484 indicating that the subject partially matched the pattern, you can restart the
485 match with additional subject data by means of the \R escape sequence. For
486 example:
487 <pre>
488 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
489 data&#62; 23ja\P\D
490 Partial match: 23ja
491 data&#62; n05\R\D
492 0: n05
493 </pre>
494 For further information about partial matching, see the
495 <a href="pcrepartial.html"><b>pcrepartial</b></a>
496 documentation.
497 </P>
498 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
499 <P>
500 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
501 is called during matching. This works with both matching functions. By default,
502 the called function displays the callout number, the start and current
503 positions in the text at the callout time, and the next pattern item to be
504 tested. For example, the output
505 <pre>
506 ---&#62;pqrabcdef
507 0 ^ ^ \d
508 </pre>
509 indicates that callout number 0 occurred for a match attempt starting at the
510 fourth character of the subject string, when the pointer was at the seventh
511 character of the data, and when the next pattern item was \d. Just one
512 circumflex is output if the start and current positions are the same.
513 </P>
514 <P>
515 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
516 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
517 callout number, the offset in the pattern, preceded by a plus, is output. For
518 example:
519 <pre>
520 re&#62; /\d?[A-E]\*/C
521 data&#62; E*
522 ---&#62;E*
523 +0 ^ \d?
524 +3 ^ [A-E]
525 +8 ^^ \*
526 +10 ^ ^
527 0: E*
528 </pre>
529 The callout function in <b>pcretest</b> returns zero (carry on matching) by
530 default, but you can use a \C item in a data line (as described above) to
531 change this.
532 </P>
533 <P>
534 Inserting callouts can be helpful when using <b>pcretest</b> to check
535 complicated regular expressions. For further information about callouts, see
536 the
537 <a href="pcrecallout.html"><b>pcrecallout</b></a>
538 documentation.
539 </P>
540 <br><a name="SEC11" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
541 <P>
542 The facilities described in this section are not available when the POSIX
543 inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
544 specified.
545 </P>
546 <P>
547 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
548 compiled pattern to a file, by following the modifiers with &#62; and a file name.
549 For example:
550 <pre>
551 /pattern/im &#62;/some/file
552 </pre>
553 See the
554 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
555 documentation for a discussion about saving and re-using compiled patterns.
556 </P>
557 <P>
558 The data that is written is binary. The first eight bytes are the length of the
559 compiled pattern data followed by the length of the optional study data, each
560 written as four bytes in big-endian order (most significant byte first). If
561 there is no study data (either the pattern was not studied, or studying did not
562 return any data), the second length is zero. The lengths are followed by an
563 exact copy of the compiled pattern. If there is additional study data, this
564 follows immediately after the compiled pattern. After writing the file,
565 <b>pcretest</b> expects to read a new pattern.
566 </P>
567 <P>
568 A saved pattern can be reloaded into <b>pcretest</b> by specifing &#60; and a file
569 name instead of a pattern. The name of the file must not contain a &#60; character,
570 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
571 characters.
572 For example:
573 <pre>
574 re&#62; &#60;/some/file
575 Compiled regex loaded from /some/file
576 No study data
577 </pre>
578 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
579 the usual way.
580 </P>
581 <P>
582 You can copy a file written by <b>pcretest</b> to a different host and reload it
583 there, even if the new host has opposite endianness to the one on which the
584 pattern was compiled. For example, you can compile on an i86 machine and run on
585 a SPARC machine.
586 </P>
587 <P>
588 File names for saving and reloading can be absolute or relative, but note that
589 the shell facility of expanding a file name that starts with a tilde (~) is not
590 available.
591 </P>
592 <P>
593 The ability to save and reload files in <b>pcretest</b> is intended for testing
594 and experimentation. It is not intended for production use because only a
595 single pattern can be written to a file. Furthermore, there is no facility for
596 supplying custom character tables for use with a reloaded pattern. If the
597 original pattern was compiled with custom tables, an attempt to match a subject
598 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
599 Finally, if you attempt to load a file that is not in the correct format, the
600 result is undefined.
601 </P>
602 <br><a name="SEC12" href="#TOC1">AUTHOR</a><br>
603 <P>
604 Philip Hazel
605 <br>
606 University Computing Service,
607 <br>
608 Cambridge CB2 3QG, England.
609 </P>
610 <P>
611 Last updated: 29 June 2006
612 <br>
613 Copyright &copy; 1997-2006 University of Cambridge.
614 <p>
615 Return to the <a href="index.html">PCRE index page</a>.
616 </p>

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