ViewVC logotype

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

Parent Directory Parent Directory | Revision Log Revision Log

Revision 111 - (show annotations)
Thu Mar 8 16:53:09 2007 UTC (14 years, 7 months ago) by ph10
File MIME type: text/html
File size: 28544 byte(s)
Error occurred while calculating annotation data.
Create the PrepareRelease script to process the documentation and create the 
.generic files for distribution, also to remove trailing spaces. Update a lot 
more of the build-time documentation. Arrange for PrepareRelease and its 
sub-scripts to be distributed.
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>
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">NON-PRINTING CHARACTERS</a>
28 <li><a name="TOC13" href="#SEC13">SEE ALSO</a>
29 <li><a name="TOC14" href="#SEC14">AUTHOR</a>
30 <li><a name="TOC15" href="#SEC15">REVISION</a>
31 </ul>
32 <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
33 <P>
34 <b>pcretest [options] [source] [destination]</b>
35 <br>
36 <br>
37 <b>pcretest</b> was written as a test program for the PCRE regular expression
38 library itself, but it can also be used for experimenting with regular
39 expressions. This document describes the features of the test program; for
40 details of the regular expressions themselves, see the
41 <a href="pcrepattern.html"><b>pcrepattern</b></a>
42 documentation. For details of the PCRE library function calls and their
43 options, see the
44 <a href="pcreapi.html"><b>pcreapi</b></a>
45 documentation.
46 </P>
47 <br><a name="SEC2" href="#TOC1">OPTIONS</a><br>
48 <P>
49 <b>-b</b>
50 Behave as if each regex has the <b>/B</b> (show bytecode) modifier; the internal
51 form is output after compilation.
52 </P>
53 <P>
54 <b>-C</b>
55 Output the version number of the PCRE library, and all available information
56 about the optional features that are included, and then exit.
57 </P>
58 <P>
59 <b>-d</b>
60 Behave as if each regex has the <b>/D</b> (debug) modifier; the internal
61 form and information about the compiled pattern is output after compilation;
62 <b>-d</b> is equivalent to <b>-b -i</b>.
63 </P>
64 <P>
65 <b>-dfa</b>
66 Behave as if each data line contains the \D escape sequence; this causes the
67 alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the
68 standard <b>pcre_exec()</b> function (more detail is given below).
69 </P>
70 <P>
71 <b>-help</b>
72 Output a brief summary these options and then exit.
73 </P>
74 <P>
75 <b>-i</b>
76 Behave as if each regex has the <b>/I</b> modifier; information about the
77 compiled pattern is given after compilation.
78 </P>
79 <P>
80 <b>-m</b>
81 Output the size of each compiled pattern after it has been compiled. This is
82 equivalent to adding <b>/M</b> to each regular expression. For compatibility
83 with earlier versions of pcretest, <b>-s</b> is a synonym for <b>-m</b>.
84 </P>
85 <P>
86 <b>-o</b> <i>osize</i>
87 Set the number of elements in the output vector that is used when calling
88 <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> to be <i>osize</i>. The default value
89 is 45, which is enough for 14 capturing subexpressions for <b>pcre_exec()</b> or
90 22 different matches for <b>pcre_dfa_exec()</b>. The vector size can be
91 changed for individual matching calls by including \O in the data line (see
92 below).
93 </P>
94 <P>
95 <b>-p</b>
96 Behave as if each regex has the <b>/P</b> modifier; the POSIX wrapper API is
97 used to call PCRE. None of the other options has any effect when <b>-p</b> is
98 set.
99 </P>
100 <P>
101 <b>-q</b>
102 Do not output the version number of <b>pcretest</b> at the start of execution.
103 </P>
104 <P>
105 <b>-S</b> <i>size</i>
106 On Unix-like systems, set the size of the runtime stack to <i>size</i>
107 megabytes.
108 </P>
109 <P>
110 <b>-t</b>
111 Run each compile, study, and match many times with a timer, and output
112 resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with
113 <b>-t</b>, because you will then get the size output a zillion times, and the
114 timing will be distorted. You can control the number of iterations that are
115 used for timing by following <b>-t</b> with a number (as a separate item on the
116 command line). For example, "-t 1000" would iterate 1000 times. The default is
117 to iterate 500000 times.
118 </P>
119 <P>
120 <b>-tm</b>
121 This is like <b>-t</b> except that it times only the matching phase, not the
122 compile or study phases.
123 </P>
124 <br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
125 <P>
126 If <b>pcretest</b> is given two filename arguments, it reads from the first and
127 writes to the second. If it is given only one filename argument, it reads from
128 that file and writes to stdout. Otherwise, it reads from stdin and writes to
129 stdout, and prompts for each line of input, using "re&#62;" to prompt for regular
130 expressions, and "data&#62;" to prompt for data lines.
131 </P>
132 <P>
133 The program handles any number of sets of input on a single input file. Each
134 set starts with a regular expression, and continues with any number of data
135 lines to be matched against the pattern.
136 </P>
137 <P>
138 Each data line is matched separately and independently. If you want to do
139 multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
140 etc., depending on the newline setting) in a single line of input to encode the
141 newline sequences. There is no limit on the length of data lines; the input
142 buffer is automatically extended if it is too small.
143 </P>
144 <P>
145 An empty line signals the end of the data lines, at which point a new regular
146 expression is read. The regular expressions are given enclosed in any
147 non-alphanumeric delimiters other than backslash, for example:
148 <pre>
149 /(a|bc)x+yz/
150 </pre>
151 White space before the initial delimiter is ignored. A regular expression may
152 be continued over several input lines, in which case the newline characters are
153 included within it. It is possible to include the delimiter within the pattern
154 by escaping it, for example
155 <pre>
156 /abc\/def/
157 </pre>
158 If you do so, the escape and the delimiter form part of the pattern, but since
159 delimiters are always non-alphanumeric, this does not affect its interpretation.
160 If the terminating delimiter is immediately followed by a backslash, for
161 example,
162 <pre>
163 /abc/\
164 </pre>
165 then a backslash is added to the end of the pattern. This is done to provide a
166 way of testing the error condition that arises if a pattern finishes with a
167 backslash, because
168 <pre>
169 /abc\/
170 </pre>
171 is interpreted as the first line of a pattern that starts with "abc/", causing
172 pcretest to read the next line as a continuation of the regular expression.
173 </P>
174 <br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
175 <P>
176 A pattern may be followed by any number of modifiers, which are mostly single
177 characters. Following Perl usage, these are referred to below as, for example,
178 "the <b>/i</b> modifier", even though the delimiter of the pattern need not
179 always be a slash, and no slash is used when writing modifiers. Whitespace may
180 appear between the final pattern delimiter and the first modifier, and between
181 the modifiers themselves.
182 </P>
183 <P>
184 The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
185 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
186 <b>pcre_compile()</b> is called. These four modifier letters have the same
187 effect as they do in Perl. For example:
188 <pre>
189 /caseless/i
190 </pre>
191 The following table shows additional modifiers for setting PCRE options that do
192 not correspond to anything in Perl:
193 <pre>
194 <b>/A</b> PCRE_ANCHORED
197 <b>/f</b> PCRE_FIRSTLINE
198 <b>/J</b> PCRE_DUPNAMES
200 <b>/U</b> PCRE_UNGREEDY
201 <b>/X</b> PCRE_EXTRA
202 <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
203 <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
204 <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
205 <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
206 </pre>
207 Those specifying line ending sequencess are literal strings as shown. This
208 example sets multiline matching with CRLF as the line ending sequence:
209 <pre>
210 /^abc/m&#60;crlf&#62;
211 </pre>
212 Details of the meanings of these PCRE options are given in the
213 <a href="pcreapi.html"><b>pcreapi</b></a>
214 documentation.
215 </P>
216 <br><b>
217 Finding all matches in a string
218 </b><br>
219 <P>
220 Searching for all possible matches within each subject string can be requested
221 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
222 again to search the remainder of the subject string. The difference between
223 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
224 <b>pcre_exec()</b> to start searching at a new point within the entire string
225 (which is in effect what Perl does), whereas the latter passes over a shortened
226 substring. This makes a difference to the matching process if the pattern
227 begins with a lookbehind assertion (including \b or \B).
228 </P>
229 <P>
230 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
231 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
232 flags set in order to search for another, non-empty, match at the same point.
233 If this second match fails, the start offset is advanced by one, and the normal
234 match is retried. This imitates the way Perl handles such cases when using the
235 <b>/g</b> modifier or the <b>split()</b> function.
236 </P>
237 <br><b>
238 Other modifiers
239 </b><br>
240 <P>
241 There are yet more modifiers for controlling the way <b>pcretest</b>
242 operates.
243 </P>
244 <P>
245 The <b>/+</b> modifier requests that as well as outputting the substring that
246 matched the entire pattern, pcretest should in addition output the remainder of
247 the subject string. This is useful for tests where the subject contains
248 multiple copies of the same substring.
249 </P>
250 <P>
251 The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
252 output a representation of the compiled byte code after compilation.
253 </P>
254 <P>
255 The <b>/L</b> modifier must be followed directly by the name of a locale, for
256 example,
257 <pre>
258 /pattern/Lfr_FR
259 </pre>
260 For this reason, it must be the last modifier. The given locale is set,
261 <b>pcre_maketables()</b> is called to build a set of character tables for the
262 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
263 regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
264 pointer; that is, <b>/L</b> applies only to the expression on which it appears.
265 </P>
266 <P>
267 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
268 compiled pattern (whether it is anchored, has a fixed first character, and
269 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
270 pattern. If the pattern is studied, the results of that are also output.
271 </P>
272 <P>
273 The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
274 <b>/BI</b>, that is, both the \fP/B\fP and the <b>/I</b> modifiers.
275 </P>
276 <P>
277 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
278 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
279 facility is for testing the feature in PCRE that allows it to execute patterns
280 that were compiled on a host with a different endianness. This feature is not
281 available when the POSIX interface to PCRE is being used, that is, when the
282 <b>/P</b> pattern modifier is specified. See also the section about saving and
283 reloading compiled patterns below.
284 </P>
285 <P>
286 The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
287 expression has been compiled, and the results used when the expression is
288 matched.
289 </P>
290 <P>
291 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
292 pattern to be output.
293 </P>
294 <P>
295 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
296 API rather than its native API. When this is done, all other modifiers except
297 <b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
298 present, and REG_NEWLINE is set if <b>/m</b> is present. The wrapper functions
299 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
300 </P>
301 <P>
302 The <b>/8</b> modifier causes <b>pcretest</b> to call PCRE with the PCRE_UTF8
303 option set. This turns on support for UTF-8 character handling in PCRE,
304 provided that it was compiled with this support enabled. This modifier also
305 causes any non-printing characters in output strings to be printed using the
306 \x{hh...} notation if they are valid UTF-8 sequences.
307 </P>
308 <P>
309 If the <b>/?</b> modifier is used with <b>/8</b>, it causes <b>pcretest</b> to
310 call <b>pcre_compile()</b> with the PCRE_NO_UTF8_CHECK option, to suppress the
311 checking of the string for UTF-8 validity.
312 </P>
313 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
314 <P>
315 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
316 whitespace is removed, and it is then scanned for \ escapes. Some of these are
317 pretty esoteric features, intended for checking out some of the more
318 complicated features of PCRE. If you are just testing "ordinary" regular
319 expressions, you probably don't need any of these. The following escapes are
320 recognized:
321 <pre>
322 \a alarm (BEL, \x07)
323 \b backspace (\x08)
324 \e escape (\x27)
325 \f formfeed (\x0c)
326 \n newline (\x0a)
327 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
328 \r carriage return (\x0d)
329 \t tab (\x09)
330 \v vertical tab (\x0b)
331 \nnn octal character (up to 3 octal digits)
332 \xhh hexadecimal character (up to 2 hex digits)
333 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
334 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
335 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
336 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
337 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
338 ated by next non alphanumeric character)
339 \C+ show the current captured substrings at callout time
340 \C- do not supply a callout function
341 \C!n return 1 instead of 0 when callout number n is reached
342 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
343 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
344 \D use the <b>pcre_dfa_exec()</b> match function
345 \F only shortest match for <b>pcre_dfa_exec()</b>
346 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
347 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
348 ated by next non-alphanumeric character)
349 \L call pcre_get_substringlist() after a successful match
350 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
351 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
352 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
353 \P pass the PCRE_PARTIAL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
354 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
355 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
356 \S output details of memory get/free calls during matching
357 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
358 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
359 \&#62;dd start the match at offset dd (any number of digits);
360 this sets the <i>startoffset</i> argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
361 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
362 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
363 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
364 \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
365 </pre>
366 The escapes that specify line ending sequences are literal strings, exactly as
367 shown. No more than one newline setting should be present in any data line.
368 </P>
369 <P>
370 A backslash followed by anything else just escapes the anything else. If
371 the very last character is a backslash, it is ignored. This gives a way of
372 passing an empty line as data, since a real empty line terminates the data
373 input.
374 </P>
375 <P>
376 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
377 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
378 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
379 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
380 <i>match_limit</i> number is a measure of the amount of backtracking that takes
381 place, and checking it out can be instructive. For most simple matches, the
382 number is quite small, but for patterns with very large numbers of matching
383 possibilities, it can become large very quickly with increasing length of
384 subject string. The <i>match_limit_recursion</i> number is a measure of how much
385 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
386 to complete the match attempt.
387 </P>
388 <P>
389 When \O is used, the value specified may be higher or lower than the size set
390 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
391 the call of <b>pcre_exec()</b> for the line in which it appears.
392 </P>
393 <P>
394 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
395 API to be used, the only option-setting sequences that have any effect are \B
396 and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
397 <b>regexec()</b>.
398 </P>
399 <P>
400 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
401 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
402 any number of hexadecimal digits inside the braces. The result is from one to
403 six bytes, encoded according to the UTF-8 rules.
404 </P>
405 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
406 <P>
407 By default, <b>pcretest</b> uses the standard PCRE matching function,
408 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
409 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
410 different way, and has some restrictions. The differences between the two
411 functions are described in the
412 <a href="pcrematching.html"><b>pcrematching</b></a>
413 documentation.
414 </P>
415 <P>
416 If a data line contains the \D escape sequence, or if the command line
417 contains the <b>-dfa</b> option, the alternative matching function is called.
418 This function finds all possible matches at a given point. If, however, the \F
419 escape sequence is present in the data line, it stops after the first match is
420 found. This is always the shortest possible match.
421 </P>
422 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
423 <P>
424 This section describes the output when the normal matching function,
425 <b>pcre_exec()</b>, is being used.
426 </P>
427 <P>
428 When a match succeeds, pcretest outputs the list of captured substrings that
429 <b>pcre_exec()</b> returns, starting with number 0 for the string that matched
430 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
431 when <b>pcre_exec()</b> returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
432 respectively, and otherwise the PCRE negative error number. Here is an example
433 of an interactive <b>pcretest</b> run.
434 <pre>
435 $ pcretest
436 PCRE version 7.0 30-Nov-2006
438 re&#62; /^abc(\d+)/
439 data&#62; abc123
440 0: abc123
441 1: 123
442 data&#62; xyz
443 No match
444 </pre>
445 If the strings contain any non-printing characters, they are output as \0x
446 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
447 pattern. See below for the definition of non-printing characters. If the
448 pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
449 the the rest of the subject string, identified by "0+" like this:
450 <pre>
451 re&#62; /cat/+
452 data&#62; cataract
453 0: cat
454 0+ aract
455 </pre>
456 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
457 matching attempts are output in sequence, like this:
458 <pre>
459 re&#62; /\Bi(\w\w)/g
460 data&#62; Mississippi
461 0: iss
462 1: ss
463 0: iss
464 1: ss
465 0: ipp
466 1: pp
467 </pre>
468 "No match" is output only if the first match attempt fails.
469 </P>
470 <P>
471 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
472 data line that is successfully matched, the substrings extracted by the
473 convenience functions are output with C, G, or L after the string number
474 instead of a colon. This is in addition to the normal full list. The string
475 length (that is, the return from the extraction function) is given in
476 parentheses after each string for <b>\C</b> and <b>\G</b>.
477 </P>
478 <P>
479 Note that whereas patterns can be continued over several lines (a plain "&#62;"
480 prompt is used for continuations), data lines may not. However newlines can be
481 included in data by means of the \n escape (or \r, \r\n, etc., depending on
482 the newline sequence setting).
483 </P>
485 <P>
486 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
487 means of the \D escape sequence or the <b>-dfa</b> command line option), the
488 output consists of a list of all the matches that start at the first point in
489 the subject where there is at least one match. For example:
490 <pre>
491 re&#62; /(tang|tangerine|tan)/
492 data&#62; yellow tangerine\D
493 0: tangerine
494 1: tang
495 2: tan
496 </pre>
497 (Using the normal matching function on this data finds only "tang".) The
498 longest matching string is always given first (and numbered zero).
499 </P>
500 <P>
501 If <b>/g</b> is present on the pattern, the search for further matches resumes
502 at the end of the longest match. For example:
503 <pre>
504 re&#62; /(tang|tangerine|tan)/g
505 data&#62; yellow tangerine and tangy sultana\D
506 0: tangerine
507 1: tang
508 2: tan
509 0: tang
510 1: tan
511 0: tan
512 </pre>
513 Since the matching function does not support substring capture, the escape
514 sequences that are concerned with captured substrings are not relevant.
515 </P>
516 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
517 <P>
518 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
519 indicating that the subject partially matched the pattern, you can restart the
520 match with additional subject data by means of the \R escape sequence. For
521 example:
522 <pre>
523 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
524 data&#62; 23ja\P\D
525 Partial match: 23ja
526 data&#62; n05\R\D
527 0: n05
528 </pre>
529 For further information about partial matching, see the
530 <a href="pcrepartial.html"><b>pcrepartial</b></a>
531 documentation.
532 </P>
533 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
534 <P>
535 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
536 is called during matching. This works with both matching functions. By default,
537 the called function displays the callout number, the start and current
538 positions in the text at the callout time, and the next pattern item to be
539 tested. For example, the output
540 <pre>
541 ---&#62;pqrabcdef
542 0 ^ ^ \d
543 </pre>
544 indicates that callout number 0 occurred for a match attempt starting at the
545 fourth character of the subject string, when the pointer was at the seventh
546 character of the data, and when the next pattern item was \d. Just one
547 circumflex is output if the start and current positions are the same.
548 </P>
549 <P>
550 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
551 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
552 callout number, the offset in the pattern, preceded by a plus, is output. For
553 example:
554 <pre>
555 re&#62; /\d?[A-E]\*/C
556 data&#62; E*
557 ---&#62;E*
558 +0 ^ \d?
559 +3 ^ [A-E]
560 +8 ^^ \*
561 +10 ^ ^
562 0: E*
563 </pre>
564 The callout function in <b>pcretest</b> returns zero (carry on matching) by
565 default, but you can use a \C item in a data line (as described above) to
566 change this.
567 </P>
568 <P>
569 Inserting callouts can be helpful when using <b>pcretest</b> to check
570 complicated regular expressions. For further information about callouts, see
571 the
572 <a href="pcrecallout.html"><b>pcrecallout</b></a>
573 documentation.
574 </P>
575 <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
576 <P>
577 When <b>pcretest</b> is outputting text in the compiled version of a pattern,
578 bytes other than 32-126 are always treated as non-printing characters are are
579 therefore shown as hex escapes.
580 </P>
581 <P>
582 When <b>pcretest</b> is outputting text that is a matched part of a subject
583 string, it behaves in the same way, unless a different locale has been set for
584 the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
585 function to distinguish printing and non-printing characters.
586 </P>
587 <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
588 <P>
589 The facilities described in this section are not available when the POSIX
590 inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
591 specified.
592 </P>
593 <P>
594 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
595 compiled pattern to a file, by following the modifiers with &#62; and a file name.
596 For example:
597 <pre>
598 /pattern/im &#62;/some/file
599 </pre>
600 See the
601 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
602 documentation for a discussion about saving and re-using compiled patterns.
603 </P>
604 <P>
605 The data that is written is binary. The first eight bytes are the length of the
606 compiled pattern data followed by the length of the optional study data, each
607 written as four bytes in big-endian order (most significant byte first). If
608 there is no study data (either the pattern was not studied, or studying did not
609 return any data), the second length is zero. The lengths are followed by an
610 exact copy of the compiled pattern. If there is additional study data, this
611 follows immediately after the compiled pattern. After writing the file,
612 <b>pcretest</b> expects to read a new pattern.
613 </P>
614 <P>
615 A saved pattern can be reloaded into <b>pcretest</b> by specifing &#60; and a file
616 name instead of a pattern. The name of the file must not contain a &#60; character,
617 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
618 characters.
619 For example:
620 <pre>
621 re&#62; &#60;/some/file
622 Compiled regex loaded from /some/file
623 No study data
624 </pre>
625 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
626 the usual way.
627 </P>
628 <P>
629 You can copy a file written by <b>pcretest</b> to a different host and reload it
630 there, even if the new host has opposite endianness to the one on which the
631 pattern was compiled. For example, you can compile on an i86 machine and run on
632 a SPARC machine.
633 </P>
634 <P>
635 File names for saving and reloading can be absolute or relative, but note that
636 the shell facility of expanding a file name that starts with a tilde (~) is not
637 available.
638 </P>
639 <P>
640 The ability to save and reload files in <b>pcretest</b> is intended for testing
641 and experimentation. It is not intended for production use because only a
642 single pattern can be written to a file. Furthermore, there is no facility for
643 supplying custom character tables for use with a reloaded pattern. If the
644 original pattern was compiled with custom tables, an attempt to match a subject
645 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
646 Finally, if you attempt to load a file that is not in the correct format, the
647 result is undefined.
648 </P>
649 <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
650 <P>
651 <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
652 <b>pcrepartial</b>(d), \fPpcrepattern\fP(3), <b>pcreprecompile</b>(3).
653 </P>
654 <br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
655 <P>
656 Philip Hazel
657 <br>
658 University Computing Service
659 <br>
660 Cambridge CB2 3QH, England.
661 <br>
662 </P>
663 <br><a name="SEC15" href="#TOC1">REVISION</a><br>
664 <P>
665 Last updated: 06 March 2007
666 <br>
667 Copyright &copy; 1997-2007 University of Cambridge.
668 <br>
669 <p>
670 Return to the <a href="index.html">PCRE index page</a>.
671 </p>


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

  ViewVC Help
Powered by ViewVC 1.1.5