ViewVC logotype

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

Parent Directory Parent Directory | Revision Log Revision Log

Revision 289 - (show annotations)
Sun Dec 23 12:17:20 2007 UTC (13 years, 10 months ago) by ph10
File MIME type: text/html
File size: 30307 byte(s)
Error occurred while calculating annotation data.
Tidies for 7.5-RC1 release.
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 When <b>pcretest</b> is built, a configuration option can specify that it should
134 be linked with the <b>libreadline</b> library. When this is done, if the input
135 is from a terminal, it is read using the <b>readline()</b> function. This
136 provides line-editing and history facilities. The output from the <b>-help</b>
137 option states whether or not <b>readline()</b> will be used.
138 </P>
139 <P>
140 The program handles any number of sets of input on a single input file. Each
141 set starts with a regular expression, and continues with any number of data
142 lines to be matched against the pattern.
143 </P>
144 <P>
145 Each data line is matched separately and independently. If you want to do
146 multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
147 etc., depending on the newline setting) in a single line of input to encode the
148 newline sequences. There is no limit on the length of data lines; the input
149 buffer is automatically extended if it is too small.
150 </P>
151 <P>
152 An empty line signals the end of the data lines, at which point a new regular
153 expression is read. The regular expressions are given enclosed in any
154 non-alphanumeric delimiters other than backslash, for example:
155 <pre>
156 /(a|bc)x+yz/
157 </pre>
158 White space before the initial delimiter is ignored. A regular expression may
159 be continued over several input lines, in which case the newline characters are
160 included within it. It is possible to include the delimiter within the pattern
161 by escaping it, for example
162 <pre>
163 /abc\/def/
164 </pre>
165 If you do so, the escape and the delimiter form part of the pattern, but since
166 delimiters are always non-alphanumeric, this does not affect its interpretation.
167 If the terminating delimiter is immediately followed by a backslash, for
168 example,
169 <pre>
170 /abc/\
171 </pre>
172 then a backslash is added to the end of the pattern. This is done to provide a
173 way of testing the error condition that arises if a pattern finishes with a
174 backslash, because
175 <pre>
176 /abc\/
177 </pre>
178 is interpreted as the first line of a pattern that starts with "abc/", causing
179 pcretest to read the next line as a continuation of the regular expression.
180 </P>
181 <br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
182 <P>
183 A pattern may be followed by any number of modifiers, which are mostly single
184 characters. Following Perl usage, these are referred to below as, for example,
185 "the <b>/i</b> modifier", even though the delimiter of the pattern need not
186 always be a slash, and no slash is used when writing modifiers. Whitespace may
187 appear between the final pattern delimiter and the first modifier, and between
188 the modifiers themselves.
189 </P>
190 <P>
191 The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
192 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
193 <b>pcre_compile()</b> is called. These four modifier letters have the same
194 effect as they do in Perl. For example:
195 <pre>
196 /caseless/i
197 </pre>
198 The following table shows additional modifiers for setting PCRE options that do
199 not correspond to anything in Perl:
200 <pre>
201 <b>/A</b> PCRE_ANCHORED
204 <b>/f</b> PCRE_FIRSTLINE
205 <b>/J</b> PCRE_DUPNAMES
207 <b>/U</b> PCRE_UNGREEDY
208 <b>/X</b> PCRE_EXTRA
209 <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
210 <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
211 <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
212 <b>/&#60;anycrlf&#62;</b> PCRE_NEWLINE_ANYCRLF
213 <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
214 <b>/&#60;bsr_anycrlf&#62;</b> PCRE_BSR_ANYCRLF
215 <b>/&#60;bsr_unicode&#62;</b> PCRE_BSR_UNICODE
216 </pre>
217 Those specifying line ending sequences are literal strings as shown, but the
218 letters can be in either case. This example sets multiline matching with CRLF
219 as the line ending sequence:
220 <pre>
221 /^abc/m&#60;crlf&#62;
222 </pre>
223 Details of the meanings of these PCRE options are given in the
224 <a href="pcreapi.html"><b>pcreapi</b></a>
225 documentation.
226 </P>
227 <br><b>
228 Finding all matches in a string
229 </b><br>
230 <P>
231 Searching for all possible matches within each subject string can be requested
232 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
233 again to search the remainder of the subject string. The difference between
234 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
235 <b>pcre_exec()</b> to start searching at a new point within the entire string
236 (which is in effect what Perl does), whereas the latter passes over a shortened
237 substring. This makes a difference to the matching process if the pattern
238 begins with a lookbehind assertion (including \b or \B).
239 </P>
240 <P>
241 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
242 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
243 flags set in order to search for another, non-empty, match at the same point.
244 If this second match fails, the start offset is advanced by one, and the normal
245 match is retried. This imitates the way Perl handles such cases when using the
246 <b>/g</b> modifier or the <b>split()</b> function.
247 </P>
248 <br><b>
249 Other modifiers
250 </b><br>
251 <P>
252 There are yet more modifiers for controlling the way <b>pcretest</b>
253 operates.
254 </P>
255 <P>
256 The <b>/+</b> modifier requests that as well as outputting the substring that
257 matched the entire pattern, pcretest should in addition output the remainder of
258 the subject string. This is useful for tests where the subject contains
259 multiple copies of the same substring.
260 </P>
261 <P>
262 The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
263 output a representation of the compiled byte code after compilation. Normally
264 this information contains length and offset values; however, if <b>/Z</b> is
265 also present, this data is replaced by spaces. This is a special feature for
266 use in the automatic test scripts; it ensures that the same output is generated
267 for different internal link sizes.
268 </P>
269 <P>
270 The <b>/L</b> modifier must be followed directly by the name of a locale, for
271 example,
272 <pre>
273 /pattern/Lfr_FR
274 </pre>
275 For this reason, it must be the last modifier. The given locale is set,
276 <b>pcre_maketables()</b> is called to build a set of character tables for the
277 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
278 regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
279 pointer; that is, <b>/L</b> applies only to the expression on which it appears.
280 </P>
281 <P>
282 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
283 compiled pattern (whether it is anchored, has a fixed first character, and
284 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
285 pattern. If the pattern is studied, the results of that are also output.
286 </P>
287 <P>
288 The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
289 <b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
290 </P>
291 <P>
292 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
293 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
294 facility is for testing the feature in PCRE that allows it to execute patterns
295 that were compiled on a host with a different endianness. This feature is not
296 available when the POSIX interface to PCRE is being used, that is, when the
297 <b>/P</b> pattern modifier is specified. See also the section about saving and
298 reloading compiled patterns below.
299 </P>
300 <P>
301 The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
302 expression has been compiled, and the results used when the expression is
303 matched.
304 </P>
305 <P>
306 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
307 pattern to be output.
308 </P>
309 <P>
310 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
311 API rather than its native API. When this is done, all other modifiers except
312 <b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
313 present, and REG_NEWLINE is set if <b>/m</b> is present. The wrapper functions
314 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
315 </P>
316 <P>
317 The <b>/8</b> modifier causes <b>pcretest</b> to call PCRE with the PCRE_UTF8
318 option set. This turns on support for UTF-8 character handling in PCRE,
319 provided that it was compiled with this support enabled. This modifier also
320 causes any non-printing characters in output strings to be printed using the
321 \x{hh...} notation if they are valid UTF-8 sequences.
322 </P>
323 <P>
324 If the <b>/?</b> modifier is used with <b>/8</b>, it causes <b>pcretest</b> to
325 call <b>pcre_compile()</b> with the PCRE_NO_UTF8_CHECK option, to suppress the
326 checking of the string for UTF-8 validity.
327 </P>
328 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
329 <P>
330 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
331 whitespace is removed, and it is then scanned for \ escapes. Some of these are
332 pretty esoteric features, intended for checking out some of the more
333 complicated features of PCRE. If you are just testing "ordinary" regular
334 expressions, you probably don't need any of these. The following escapes are
335 recognized:
336 <pre>
337 \a alarm (BEL, \x07)
338 \b backspace (\x08)
339 \e escape (\x27)
340 \f formfeed (\x0c)
341 \n newline (\x0a)
342 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
343 \r carriage return (\x0d)
344 \t tab (\x09)
345 \v vertical tab (\x0b)
346 \nnn octal character (up to 3 octal digits)
347 \xhh hexadecimal character (up to 2 hex digits)
348 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
349 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
350 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
351 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
352 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
353 ated by next non alphanumeric character)
354 \C+ show the current captured substrings at callout time
355 \C- do not supply a callout function
356 \C!n return 1 instead of 0 when callout number n is reached
357 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
358 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
359 \D use the <b>pcre_dfa_exec()</b> match function
360 \F only shortest match for <b>pcre_dfa_exec()</b>
361 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
362 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
363 ated by next non-alphanumeric character)
364 \L call pcre_get_substringlist() after a successful match
365 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
366 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
367 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
368 \P pass the PCRE_PARTIAL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
369 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
370 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
371 \S output details of memory get/free calls during matching
372 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
373 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
374 \&#62;dd start the match at offset dd (any number of digits);
375 this sets the <i>startoffset</i> argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
376 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
377 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
378 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
379 \&#60;anycrlf&#62; pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
380 \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
381 </pre>
382 The escapes that specify line ending sequences are literal strings, exactly as
383 shown. No more than one newline setting should be present in any data line.
384 </P>
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 <P>
392 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
393 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
394 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
395 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
396 <i>match_limit</i> number is a measure of the amount of backtracking that takes
397 place, and checking it out can be instructive. For most simple matches, the
398 number is quite small, but for patterns with very large numbers of matching
399 possibilities, it can become large very quickly with increasing length of
400 subject string. The <i>match_limit_recursion</i> number is a measure of how much
401 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
402 to complete the match attempt.
403 </P>
404 <P>
405 When \O is used, the value specified may be higher or lower than the size set
406 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
407 the call of <b>pcre_exec()</b> for the line in which it appears.
408 </P>
409 <P>
410 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
411 API to be used, the only option-setting sequences that have any effect are \B
412 and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
413 <b>regexec()</b>.
414 </P>
415 <P>
416 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
417 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
418 any number of hexadecimal digits inside the braces. The result is from one to
419 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
420 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
421 valid Unicode code points, or indeed valid UTF-8 characters according to the
422 later rules in RFC 3629.
423 </P>
424 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
425 <P>
426 By default, <b>pcretest</b> uses the standard PCRE matching function,
427 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
428 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
429 different way, and has some restrictions. The differences between the two
430 functions are described in the
431 <a href="pcrematching.html"><b>pcrematching</b></a>
432 documentation.
433 </P>
434 <P>
435 If a data line contains the \D escape sequence, or if the command line
436 contains the <b>-dfa</b> option, the alternative matching function is called.
437 This function finds all possible matches at a given point. If, however, the \F
438 escape sequence is present in the data line, it stops after the first match is
439 found. This is always the shortest possible match.
440 </P>
441 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
442 <P>
443 This section describes the output when the normal matching function,
444 <b>pcre_exec()</b>, is being used.
445 </P>
446 <P>
447 When a match succeeds, pcretest outputs the list of captured substrings that
448 <b>pcre_exec()</b> returns, starting with number 0 for the string that matched
449 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
450 when <b>pcre_exec()</b> 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 <b>pcretest</b> run.
453 <pre>
454 $ pcretest
455 PCRE version 7.0 30-Nov-2006
457 re&#62; /^abc(\d+)/
458 data&#62; abc123
459 0: abc123
460 1: 123
461 data&#62; xyz
462 No match
463 </pre>
464 Note that unset capturing substrings that are not followed by one that is set
465 are not returned by <b>pcre_exec()</b>, and are not shown by <b>pcretest</b>. In
466 the following example, there are two capturing substrings, but when the first
467 data line is matched, the second, unset substring is not shown. An "internal"
468 unset substring is shown as "&#60;unset&#62;", as for the second data line.
469 <pre>
470 re&#62; /(a)|(b)/
471 data&#62; a
472 0: a
473 1: a
474 data&#62; b
475 0: b
476 1: &#60;unset&#62;
477 2: b
478 </pre>
479 If the strings contain any non-printing characters, they are output as \0x
480 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
481 pattern. See below for the definition of non-printing characters. If the
482 pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
483 the the rest of the subject string, identified by "0+" like this:
484 <pre>
485 re&#62; /cat/+
486 data&#62; cataract
487 0: cat
488 0+ aract
489 </pre>
490 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
491 matching attempts are output in sequence, like this:
492 <pre>
493 re&#62; /\Bi(\w\w)/g
494 data&#62; Mississippi
495 0: iss
496 1: ss
497 0: iss
498 1: ss
499 0: ipp
500 1: pp
501 </pre>
502 "No match" is output only if the first match attempt fails.
503 </P>
504 <P>
505 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
506 data line that is successfully matched, the substrings extracted by the
507 convenience functions are output with C, G, or L after the string number
508 instead of a colon. This is in addition to the normal full list. The string
509 length (that is, the return from the extraction function) is given in
510 parentheses after each string for <b>\C</b> and <b>\G</b>.
511 </P>
512 <P>
513 Note that whereas patterns can be continued over several lines (a plain "&#62;"
514 prompt is used for continuations), data lines may not. However newlines can be
515 included in data by means of the \n escape (or \r, \r\n, etc., depending on
516 the newline sequence setting).
517 </P>
519 <P>
520 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
521 means of the \D escape sequence or the <b>-dfa</b> command line option), the
522 output consists of a list of all the matches that start at the first point in
523 the subject where there is at least one match. For example:
524 <pre>
525 re&#62; /(tang|tangerine|tan)/
526 data&#62; yellow tangerine\D
527 0: tangerine
528 1: tang
529 2: tan
530 </pre>
531 (Using the normal matching function on this data finds only "tang".) The
532 longest matching string is always given first (and numbered zero).
533 </P>
534 <P>
535 If <b>/g</b> is present on the pattern, the search for further matches resumes
536 at the end of the longest match. For example:
537 <pre>
538 re&#62; /(tang|tangerine|tan)/g
539 data&#62; yellow tangerine and tangy sultana\D
540 0: tangerine
541 1: tang
542 2: tan
543 0: tang
544 1: tan
545 0: tan
546 </pre>
547 Since the matching function does not support substring capture, the escape
548 sequences that are concerned with captured substrings are not relevant.
549 </P>
550 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
551 <P>
552 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
553 indicating that the subject partially matched the pattern, you can restart the
554 match with additional subject data by means of the \R escape sequence. For
555 example:
556 <pre>
557 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
558 data&#62; 23ja\P\D
559 Partial match: 23ja
560 data&#62; n05\R\D
561 0: n05
562 </pre>
563 For further information about partial matching, see the
564 <a href="pcrepartial.html"><b>pcrepartial</b></a>
565 documentation.
566 </P>
567 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
568 <P>
569 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
570 is called during matching. This works with both matching functions. By default,
571 the called function displays the callout number, the start and current
572 positions in the text at the callout time, and the next pattern item to be
573 tested. For example, the output
574 <pre>
575 ---&#62;pqrabcdef
576 0 ^ ^ \d
577 </pre>
578 indicates that callout number 0 occurred for a match attempt starting at the
579 fourth character of the subject string, when the pointer was at the seventh
580 character of the data, and when the next pattern item was \d. Just one
581 circumflex is output if the start and current positions are the same.
582 </P>
583 <P>
584 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
585 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
586 callout number, the offset in the pattern, preceded by a plus, is output. For
587 example:
588 <pre>
589 re&#62; /\d?[A-E]\*/C
590 data&#62; E*
591 ---&#62;E*
592 +0 ^ \d?
593 +3 ^ [A-E]
594 +8 ^^ \*
595 +10 ^ ^
596 0: E*
597 </pre>
598 The callout function in <b>pcretest</b> returns zero (carry on matching) by
599 default, but you can use a \C item in a data line (as described above) to
600 change this.
601 </P>
602 <P>
603 Inserting callouts can be helpful when using <b>pcretest</b> to check
604 complicated regular expressions. For further information about callouts, see
605 the
606 <a href="pcrecallout.html"><b>pcrecallout</b></a>
607 documentation.
608 </P>
609 <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
610 <P>
611 When <b>pcretest</b> is outputting text in the compiled version of a pattern,
612 bytes other than 32-126 are always treated as non-printing characters are are
613 therefore shown as hex escapes.
614 </P>
615 <P>
616 When <b>pcretest</b> is outputting text that is a matched part of a subject
617 string, it behaves in the same way, unless a different locale has been set for
618 the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
619 function to distinguish printing and non-printing characters.
620 </P>
621 <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
622 <P>
623 The facilities described in this section are not available when the POSIX
624 inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
625 specified.
626 </P>
627 <P>
628 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
629 compiled pattern to a file, by following the modifiers with &#62; and a file name.
630 For example:
631 <pre>
632 /pattern/im &#62;/some/file
633 </pre>
634 See the
635 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
636 documentation for a discussion about saving and re-using compiled patterns.
637 </P>
638 <P>
639 The data that is written is binary. The first eight bytes are the length of the
640 compiled pattern data followed by the length of the optional study data, each
641 written as four bytes in big-endian order (most significant byte first). If
642 there is no study data (either the pattern was not studied, or studying did not
643 return any data), the second length is zero. The lengths are followed by an
644 exact copy of the compiled pattern. If there is additional study data, this
645 follows immediately after the compiled pattern. After writing the file,
646 <b>pcretest</b> expects to read a new pattern.
647 </P>
648 <P>
649 A saved pattern can be reloaded into <b>pcretest</b> by specifing &#60; and a file
650 name instead of a pattern. The name of the file must not contain a &#60; character,
651 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
652 characters.
653 For example:
654 <pre>
655 re&#62; &#60;/some/file
656 Compiled regex loaded from /some/file
657 No study data
658 </pre>
659 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
660 the usual way.
661 </P>
662 <P>
663 You can copy a file written by <b>pcretest</b> to a different host and reload it
664 there, even if the new host has opposite endianness to the one on which the
665 pattern was compiled. For example, you can compile on an i86 machine and run on
666 a SPARC machine.
667 </P>
668 <P>
669 File names for saving and reloading can be absolute or relative, but note that
670 the shell facility of expanding a file name that starts with a tilde (~) is not
671 available.
672 </P>
673 <P>
674 The ability to save and reload files in <b>pcretest</b> is intended for testing
675 and experimentation. It is not intended for production use because only a
676 single pattern can be written to a file. Furthermore, there is no facility for
677 supplying custom character tables for use with a reloaded pattern. If the
678 original pattern was compiled with custom tables, an attempt to match a subject
679 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
680 Finally, if you attempt to load a file that is not in the correct format, the
681 result is undefined.
682 </P>
683 <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
684 <P>
685 <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
686 <b>pcrepartial</b>(d), <b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
687 </P>
688 <br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
689 <P>
690 Philip Hazel
691 <br>
692 University Computing Service
693 <br>
694 Cambridge CB2 3QH, England.
695 <br>
696 </P>
697 <br><a name="SEC15" href="#TOC1">REVISION</a><br>
698 <P>
699 Last updated: 18 December 2007
700 <br>
701 Copyright &copy; 1997-2007 University of Cambridge.
702 <br>
703 <p>
704 Return to the <a href="index.html">PCRE index page</a>.
705 </p>


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

  ViewVC Help
Powered by ViewVC 1.1.5