/[pcre]/code/trunk/doc/html/pcretest.html
ViewVC logotype

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

Parent Directory Parent Directory | Revision Log Revision Log


Revision 93 - (show annotations) (download) (as text)
Sat Feb 24 21:41:42 2007 UTC (7 years, 6 months ago) by nigel
File MIME type: text/html
File size: 28441 byte(s)
Load pcre-7.0 into code/trunk.

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">NON-PRINTING CHARACTERS</a>
27 <li><a name="TOC12" href="#SEC12">SAVING AND RELOADING COMPILED PATTERNS</a>
28 <li><a name="TOC13" href="#SEC13">SEE ALSO</a>
29 <li><a name="TOC14" href="#SEC14">AUTHOR</a>
30 </ul>
31 <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
32 <P>
33 <b>pcretest [options] [source] [destination]</b>
34 <br>
35 <br>
36 <b>pcretest</b> was written as a test program for the PCRE regular expression
37 library itself, but it can also be used for experimenting with regular
38 expressions. This document describes the features of the test program; for
39 details of the regular expressions themselves, see the
40 <a href="pcrepattern.html"><b>pcrepattern</b></a>
41 documentation. For details of the PCRE library function calls and their
42 options, see the
43 <a href="pcreapi.html"><b>pcreapi</b></a>
44 documentation.
45 </P>
46 <br><a name="SEC2" href="#TOC1">OPTIONS</a><br>
47 <P>
48 <b>-b</b>
49 Behave as if each regex has the <b>/B</b> (show bytecode) modifier; the internal
50 form is output after compilation.
51 </P>
52 <P>
53 <b>-C</b>
54 Output the version number of the PCRE library, and all available information
55 about the optional features that are included, and then exit.
56 </P>
57 <P>
58 <b>-d</b>
59 Behave as if each regex has the <b>/D</b> (debug) modifier; the internal
60 form and information about the compiled pattern is output after compilation;
61 <b>-d</b> is equivalent to <b>-b -i</b>.
62 </P>
63 <P>
64 <b>-dfa</b>
65 Behave as if each data line contains the \D escape sequence; this causes the
66 alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the
67 standard <b>pcre_exec()</b> function (more detail is given below).
68 </P>
69 <P>
70 <b>-help</b>
71 Output a brief summary these options and then exit.
72 </P>
73 <P>
74 <b>-i</b>
75 Behave as if each regex has the <b>/I</b> modifier; information about the
76 compiled pattern is given after compilation.
77 </P>
78 <P>
79 <b>-m</b>
80 Output the size of each compiled pattern after it has been compiled. This is
81 equivalent to adding <b>/M</b> to each regular expression. For compatibility
82 with earlier versions of pcretest, <b>-s</b> is a synonym for <b>-m</b>.
83 </P>
84 <P>
85 <b>-o</b> <i>osize</i>
86 Set the number of elements in the output vector that is used when calling
87 <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> to be <i>osize</i>. The default value
88 is 45, which is enough for 14 capturing subexpressions for <b>pcre_exec()</b> or
89 22 different matches for <b>pcre_dfa_exec()</b>. The vector size can be
90 changed for individual matching calls by including \O in the data line (see
91 below).
92 </P>
93 <P>
94 <b>-p</b>
95 Behave as if each regex has the <b>/P</b> modifier; the POSIX wrapper API is
96 used to call PCRE. None of the other options has any effect when <b>-p</b> is
97 set.
98 </P>
99 <P>
100 <b>-q</b>
101 Do not output the version number of <b>pcretest</b> at the start of execution.
102 </P>
103 <P>
104 <b>-S</b> <i>size</i>
105 On Unix-like systems, set the size of the runtime stack to <i>size</i>
106 megabytes.
107 </P>
108 <P>
109 <b>-t</b>
110 Run each compile, study, and match many times with a timer, and output
111 resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with
112 <b>-t</b>, because you will then get the size output a zillion times, and the
113 timing will be distorted. You can control the number of iterations that are
114 used for timing by following <b>-t</b> with a number (as a separate item on the
115 command line). For example, "-t 1000" would iterate 1000 times. The default is
116 to iterate 500000 times.
117 </P>
118 <P>
119 <b>-tm</b>
120 This is like <b>-t</b> except that it times only the matching phase, not the
121 compile or study phases.
122 </P>
123 <br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
124 <P>
125 If <b>pcretest</b> is given two filename arguments, it reads from the first and
126 writes to the second. If it is given only one filename argument, it reads from
127 that file and writes to stdout. Otherwise, it reads from stdin and writes to
128 stdout, and prompts for each line of input, using "re&#62;" to prompt for regular
129 expressions, and "data&#62;" to prompt for data lines.
130 </P>
131 <P>
132 The program handles any number of sets of input on a single input file. Each
133 set starts with a regular expression, and continues with any number of data
134 lines to be matched against the pattern.
135 </P>
136 <P>
137 Each data line is matched separately and independently. If you want to do
138 multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
139 etc., depending on the newline setting) in a single line of input to encode the
140 newline sequences. There is no limit on the length of data lines; the input
141 buffer is automatically extended if it is too small.
142 </P>
143 <P>
144 An empty line signals the end of the data lines, at which point a new regular
145 expression is read. The regular expressions are given enclosed in any
146 non-alphanumeric delimiters other than backslash, for example:
147 <pre>
148 /(a|bc)x+yz/
149 </pre>
150 White space before the initial delimiter is ignored. A regular expression may
151 be continued over several input lines, in which case the newline characters are
152 included within it. It is possible to include the delimiter within the pattern
153 by escaping it, for example
154 <pre>
155 /abc\/def/
156 </pre>
157 If you do so, the escape and the delimiter form part of the pattern, but since
158 delimiters are always non-alphanumeric, this does not affect its interpretation.
159 If the terminating delimiter is immediately followed by a backslash, for
160 example,
161 <pre>
162 /abc/\
163 </pre>
164 then a backslash is added to the end of the pattern. This is done to provide a
165 way of testing the error condition that arises if a pattern finishes with a
166 backslash, because
167 <pre>
168 /abc\/
169 </pre>
170 is interpreted as the first line of a pattern that starts with "abc/", causing
171 pcretest to read the next line as a continuation of the regular expression.
172 </P>
173 <br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
174 <P>
175 A pattern may be followed by any number of modifiers, which are mostly single
176 characters. Following Perl usage, these are referred to below as, for example,
177 "the <b>/i</b> modifier", even though the delimiter of the pattern need not
178 always be a slash, and no slash is used when writing modifiers. Whitespace may
179 appear between the final pattern delimiter and the first modifier, and between
180 the modifiers themselves.
181 </P>
182 <P>
183 The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
184 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
185 <b>pcre_compile()</b> is called. These four modifier letters have the same
186 effect as they do in Perl. For example:
187 <pre>
188 /caseless/i
189 </pre>
190 The following table shows additional modifiers for setting PCRE options that do
191 not correspond to anything in Perl:
192 <pre>
193 <b>/A</b> PCRE_ANCHORED
194 <b>/C</b> PCRE_AUTO_CALLOUT
195 <b>/E</b> PCRE_DOLLAR_ENDONLY
196 <b>/f</b> PCRE_FIRSTLINE
197 <b>/J</b> PCRE_DUPNAMES
198 <b>/N</b> PCRE_NO_AUTO_CAPTURE
199 <b>/U</b> PCRE_UNGREEDY
200 <b>/X</b> PCRE_EXTRA
201 <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
202 <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
203 <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
204 <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
205 </pre>
206 Those specifying line ending sequencess are literal strings as shown. This
207 example sets multiline matching with CRLF as the line ending sequence:
208 <pre>
209 /^abc/m&#60;crlf&#62;
210 </pre>
211 Details of the meanings of these PCRE options are given in the
212 <a href="pcreapi.html"><b>pcreapi</b></a>
213 documentation.
214 </P>
215 <br><b>
216 Finding all matches in a string
217 </b><br>
218 <P>
219 Searching for all possible matches within each subject string can be requested
220 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
221 again to search the remainder of the subject string. The difference between
222 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
223 <b>pcre_exec()</b> to start searching at a new point within the entire string
224 (which is in effect what Perl does), whereas the latter passes over a shortened
225 substring. This makes a difference to the matching process if the pattern
226 begins with a lookbehind assertion (including \b or \B).
227 </P>
228 <P>
229 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
230 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
231 flags set in order to search for another, non-empty, match at the same point.
232 If this second match fails, the start offset is advanced by one, and the normal
233 match is retried. This imitates the way Perl handles such cases when using the
234 <b>/g</b> modifier or the <b>split()</b> function.
235 </P>
236 <br><b>
237 Other modifiers
238 </b><br>
239 <P>
240 There are yet more modifiers for controlling the way <b>pcretest</b>
241 operates.
242 </P>
243 <P>
244 The <b>/+</b> modifier requests that as well as outputting the substring that
245 matched the entire pattern, pcretest should in addition output the remainder of
246 the subject string. This is useful for tests where the subject contains
247 multiple copies of the same substring.
248 </P>
249 <P>
250 The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
251 output a representation of the compiled byte code after compilation.
252 </P>
253 <P>
254 The <b>/L</b> modifier must be followed directly by the name of a locale, for
255 example,
256 <pre>
257 /pattern/Lfr_FR
258 </pre>
259 For this reason, it must be the last modifier. The given locale is set,
260 <b>pcre_maketables()</b> is called to build a set of character tables for the
261 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
262 regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
263 pointer; that is, <b>/L</b> applies only to the expression on which it appears.
264 </P>
265 <P>
266 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
267 compiled pattern (whether it is anchored, has a fixed first character, and
268 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
269 pattern. If the pattern is studied, the results of that are also output.
270 </P>
271 <P>
272 The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
273 <b>/BI</b>, that is, both the \fP/B\fP and the <b>/I</b> modifiers.
274 </P>
275 <P>
276 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
277 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
278 facility is for testing the feature in PCRE that allows it to execute patterns
279 that were compiled on a host with a different endianness. This feature is not
280 available when the POSIX interface to PCRE is being used, that is, when the
281 <b>/P</b> pattern modifier is specified. See also the section about saving and
282 reloading compiled patterns below.
283 </P>
284 <P>
285 The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
286 expression has been compiled, and the results used when the expression is
287 matched.
288 </P>
289 <P>
290 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
291 pattern to be output.
292 </P>
293 <P>
294 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
295 API rather than its native API. When this is done, all other modifiers except
296 <b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
297 present, and REG_NEWLINE is set if <b>/m</b> is present. The wrapper functions
298 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
299 </P>
300 <P>
301 The <b>/8</b> modifier causes <b>pcretest</b> to call PCRE with the PCRE_UTF8
302 option set. This turns on support for UTF-8 character handling in PCRE,
303 provided that it was compiled with this support enabled. This modifier also
304 causes any non-printing characters in output strings to be printed using the
305 \x{hh...} notation if they are valid UTF-8 sequences.
306 </P>
307 <P>
308 If the <b>/?</b> modifier is used with <b>/8</b>, it causes <b>pcretest</b> to
309 call <b>pcre_compile()</b> with the PCRE_NO_UTF8_CHECK option, to suppress the
310 checking of the string for UTF-8 validity.
311 </P>
312 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
313 <P>
314 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
315 whitespace is removed, and it is then scanned for \ escapes. Some of these are
316 pretty esoteric features, intended for checking out some of the more
317 complicated features of PCRE. If you are just testing "ordinary" regular
318 expressions, you probably don't need any of these. The following escapes are
319 recognized:
320 <pre>
321 \a alarm (BEL, \x07)
322 \b backspace (\x08)
323 \e escape (\x27)
324 \f formfeed (\x0c)
325 \n newline (\x0a)
326 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
327 \r carriage return (\x0d)
328 \t tab (\x09)
329 \v vertical tab (\x0b)
330 \nnn octal character (up to 3 octal digits)
331 \xhh hexadecimal character (up to 2 hex digits)
332 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
333 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
334 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
335 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
336 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
337 ated by next non alphanumeric character)
338 \C+ show the current captured substrings at callout time
339 \C- do not supply a callout function
340 \C!n return 1 instead of 0 when callout number n is reached
341 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
342 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
343 \D use the <b>pcre_dfa_exec()</b> match function
344 \F only shortest match for <b>pcre_dfa_exec()</b>
345 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
346 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
347 ated by next non-alphanumeric character)
348 \L call pcre_get_substringlist() after a successful match
349 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
350 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
351 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
352 \P pass the PCRE_PARTIAL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
353 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
354 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
355 \S output details of memory get/free calls during matching
356 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
357 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
358 \&#62;dd start the match at offset dd (any number of digits);
359 this sets the <i>startoffset</i> argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
360 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
361 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
362 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
363 \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
364 </pre>
365 The escapes that specify line ending sequences are literal strings, exactly as
366 shown. No more than one newline setting should be present in any data line.
367 </P>
368 <P>
369 A backslash followed by anything else just escapes the anything else. If
370 the very last character is a backslash, it is ignored. This gives a way of
371 passing an empty line as data, since a real empty line terminates the data
372 input.
373 </P>
374 <P>
375 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
376 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
377 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
378 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
379 <i>match_limit</i> number is a measure of the amount of backtracking that takes
380 place, and checking it out can be instructive. For most simple matches, the
381 number is quite small, but for patterns with very large numbers of matching
382 possibilities, it can become large very quickly with increasing length of
383 subject string. The <i>match_limit_recursion</i> number is a measure of how much
384 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
385 to complete the match attempt.
386 </P>
387 <P>
388 When \O is used, the value specified may be higher or lower than the size set
389 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
390 the call of <b>pcre_exec()</b> for the line in which it appears.
391 </P>
392 <P>
393 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
394 API to be used, the only option-setting sequences that have any effect are \B
395 and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
396 <b>regexec()</b>.
397 </P>
398 <P>
399 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
400 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
401 any number of hexadecimal digits inside the braces. The result is from one to
402 six bytes, encoded according to the UTF-8 rules.
403 </P>
404 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
405 <P>
406 By default, <b>pcretest</b> uses the standard PCRE matching function,
407 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
408 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
409 different way, and has some restrictions. The differences between the two
410 functions are described in the
411 <a href="pcrematching.html"><b>pcrematching</b></a>
412 documentation.
413 </P>
414 <P>
415 If a data line contains the \D escape sequence, or if the command line
416 contains the <b>-dfa</b> option, the alternative matching function is called.
417 This function finds all possible matches at a given point. If, however, the \F
418 escape sequence is present in the data line, it stops after the first match is
419 found. This is always the shortest possible match.
420 </P>
421 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
422 <P>
423 This section describes the output when the normal matching function,
424 <b>pcre_exec()</b>, is being used.
425 </P>
426 <P>
427 When a match succeeds, pcretest outputs the list of captured substrings that
428 <b>pcre_exec()</b> returns, starting with number 0 for the string that matched
429 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
430 when <b>pcre_exec()</b> returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
431 respectively, and otherwise the PCRE negative error number. Here is an example
432 of an interactive <b>pcretest</b> run.
433 <pre>
434 $ pcretest
435 PCRE version 7.0 30-Nov-2006
436
437 re&#62; /^abc(\d+)/
438 data&#62; abc123
439 0: abc123
440 1: 123
441 data&#62; xyz
442 No match
443 </pre>
444 If the strings contain any non-printing characters, they are output as \0x
445 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
446 pattern. See below for the definition of non-printing characters. If the
447 pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
448 the the rest of the subject string, identified by "0+" like this:
449 <pre>
450 re&#62; /cat/+
451 data&#62; cataract
452 0: cat
453 0+ aract
454 </pre>
455 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
456 matching attempts are output in sequence, like this:
457 <pre>
458 re&#62; /\Bi(\w\w)/g
459 data&#62; Mississippi
460 0: iss
461 1: ss
462 0: iss
463 1: ss
464 0: ipp
465 1: pp
466 </pre>
467 "No match" is output only if the first match attempt fails.
468 </P>
469 <P>
470 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
471 data line that is successfully matched, the substrings extracted by the
472 convenience functions are output with C, G, or L after the string number
473 instead of a colon. This is in addition to the normal full list. The string
474 length (that is, the return from the extraction function) is given in
475 parentheses after each string for <b>\C</b> and <b>\G</b>.
476 </P>
477 <P>
478 Note that whereas patterns can be continued over several lines (a plain "&#62;"
479 prompt is used for continuations), data lines may not. However newlines can be
480 included in data by means of the \n escape (or \r, \r\n, etc., depending on
481 the newline sequence setting).
482 </P>
483 <br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
484 <P>
485 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
486 means of the \D escape sequence or the <b>-dfa</b> command line option), the
487 output consists of a list of all the matches that start at the first point in
488 the subject where there is at least one match. For example:
489 <pre>
490 re&#62; /(tang|tangerine|tan)/
491 data&#62; yellow tangerine\D
492 0: tangerine
493 1: tang
494 2: tan
495 </pre>
496 (Using the normal matching function on this data finds only "tang".) The
497 longest matching string is always given first (and numbered zero).
498 </P>
499 <P>
500 If <b>/g</b> is present on the pattern, the search for further matches resumes
501 at the end of the longest match. For example:
502 <pre>
503 re&#62; /(tang|tangerine|tan)/g
504 data&#62; yellow tangerine and tangy sultana\D
505 0: tangerine
506 1: tang
507 2: tan
508 0: tang
509 1: tan
510 0: tan
511 </pre>
512 Since the matching function does not support substring capture, the escape
513 sequences that are concerned with captured substrings are not relevant.
514 </P>
515 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
516 <P>
517 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
518 indicating that the subject partially matched the pattern, you can restart the
519 match with additional subject data by means of the \R escape sequence. For
520 example:
521 <pre>
522 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
523 data&#62; 23ja\P\D
524 Partial match: 23ja
525 data&#62; n05\R\D
526 0: n05
527 </pre>
528 For further information about partial matching, see the
529 <a href="pcrepartial.html"><b>pcrepartial</b></a>
530 documentation.
531 </P>
532 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
533 <P>
534 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
535 is called during matching. This works with both matching functions. By default,
536 the called function displays the callout number, the start and current
537 positions in the text at the callout time, and the next pattern item to be
538 tested. For example, the output
539 <pre>
540 ---&#62;pqrabcdef
541 0 ^ ^ \d
542 </pre>
543 indicates that callout number 0 occurred for a match attempt starting at the
544 fourth character of the subject string, when the pointer was at the seventh
545 character of the data, and when the next pattern item was \d. Just one
546 circumflex is output if the start and current positions are the same.
547 </P>
548 <P>
549 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
550 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
551 callout number, the offset in the pattern, preceded by a plus, is output. For
552 example:
553 <pre>
554 re&#62; /\d?[A-E]\*/C
555 data&#62; E*
556 ---&#62;E*
557 +0 ^ \d?
558 +3 ^ [A-E]
559 +8 ^^ \*
560 +10 ^ ^
561 0: E*
562 </pre>
563 The callout function in <b>pcretest</b> returns zero (carry on matching) by
564 default, but you can use a \C item in a data line (as described above) to
565 change this.
566 </P>
567 <P>
568 Inserting callouts can be helpful when using <b>pcretest</b> to check
569 complicated regular expressions. For further information about callouts, see
570 the
571 <a href="pcrecallout.html"><b>pcrecallout</b></a>
572 documentation.
573 </P>
574 <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
575 <P>
576 When <b>pcretest</b> is outputting text in the compiled version of a pattern,
577 bytes other than 32-126 are always treated as non-printing characters are are
578 therefore shown as hex escapes.
579 </P>
580 <P>
581 When <b>pcretest</b> is outputting text that is a matched part of a subject
582 string, it behaves in the same way, unless a different locale has been set for
583 the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
584 function to distinguish printing and non-printing characters.
585 </P>
586 <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
587 <P>
588 The facilities described in this section are not available when the POSIX
589 inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
590 specified.
591 </P>
592 <P>
593 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
594 compiled pattern to a file, by following the modifiers with &#62; and a file name.
595 For example:
596 <pre>
597 /pattern/im &#62;/some/file
598 </pre>
599 See the
600 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
601 documentation for a discussion about saving and re-using compiled patterns.
602 </P>
603 <P>
604 The data that is written is binary. The first eight bytes are the length of the
605 compiled pattern data followed by the length of the optional study data, each
606 written as four bytes in big-endian order (most significant byte first). If
607 there is no study data (either the pattern was not studied, or studying did not
608 return any data), the second length is zero. The lengths are followed by an
609 exact copy of the compiled pattern. If there is additional study data, this
610 follows immediately after the compiled pattern. After writing the file,
611 <b>pcretest</b> expects to read a new pattern.
612 </P>
613 <P>
614 A saved pattern can be reloaded into <b>pcretest</b> by specifing &#60; and a file
615 name instead of a pattern. The name of the file must not contain a &#60; character,
616 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
617 characters.
618 For example:
619 <pre>
620 re&#62; &#60;/some/file
621 Compiled regex loaded from /some/file
622 No study data
623 </pre>
624 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
625 the usual way.
626 </P>
627 <P>
628 You can copy a file written by <b>pcretest</b> to a different host and reload it
629 there, even if the new host has opposite endianness to the one on which the
630 pattern was compiled. For example, you can compile on an i86 machine and run on
631 a SPARC machine.
632 </P>
633 <P>
634 File names for saving and reloading can be absolute or relative, but note that
635 the shell facility of expanding a file name that starts with a tilde (~) is not
636 available.
637 </P>
638 <P>
639 The ability to save and reload files in <b>pcretest</b> is intended for testing
640 and experimentation. It is not intended for production use because only a
641 single pattern can be written to a file. Furthermore, there is no facility for
642 supplying custom character tables for use with a reloaded pattern. If the
643 original pattern was compiled with custom tables, an attempt to match a subject
644 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
645 Finally, if you attempt to load a file that is not in the correct format, the
646 result is undefined.
647 </P>
648 <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
649 <P>
650 <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
651 <b>pcrepartial</b>(d), \fPpcrepattern\fP(3), <b>pcreprecompile</b>(3).
652 </P>
653 <br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
654 <P>
655 Philip Hazel
656 <br>
657 University Computing Service,
658 <br>
659 Cambridge CB2 3QH, England.
660 </P>
661 <P>
662 Last updated: 30 November 2006
663 <br>
664 Copyright &copy; 1997-2006 University of Cambridge.
665 <p>
666 Return to the <a href="index.html">PCRE index page</a>.
667 </p>

webmaster@exim.org
ViewVC Help
Powered by ViewVC 1.1.12