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1 <html>
2 <head>
3 <title>pcretest specification</title>
4 </head>
5 <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6 <h1>pcretest man page</h1>
7 <p>
8 Return to the <a href="index.html">PCRE index page</a>.
9 </p>
10 <p>
11 This page is part of the PCRE HTML documentation. It was generated automatically
12 from the original man page. If there is any nonsense in it, please consult the
13 man page, in case the conversion went wrong.
14 <br>
15 <ul>
16 <li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
17 <li><a name="TOC2" href="#SEC2">OPTIONS</a>
18 <li><a name="TOC3" href="#SEC3">DESCRIPTION</a>
19 <li><a name="TOC4" href="#SEC4">PATTERN MODIFIERS</a>
20 <li><a name="TOC5" href="#SEC5">DATA LINES</a>
21 <li><a name="TOC6" href="#SEC6">THE ALTERNATIVE MATCHING FUNCTION</a>
22 <li><a name="TOC7" href="#SEC7">DEFAULT OUTPUT FROM PCRETEST</a>
23 <li><a name="TOC8" href="#SEC8">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
24 <li><a name="TOC9" href="#SEC9">RESTARTING AFTER A PARTIAL MATCH</a>
25 <li><a name="TOC10" href="#SEC10">CALLOUTS</a>
26 <li><a name="TOC11" href="#SEC11">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 <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
195 <b>/C</b> PCRE_AUTO_CALLOUT
196 <b>/E</b> PCRE_DOLLAR_ENDONLY
197 <b>/f</b> PCRE_FIRSTLINE
198 <b>/J</b> PCRE_DUPNAMES
199 <b>/N</b> PCRE_NO_AUTO_CAPTURE
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;anycrlf&#62;</b> PCRE_NEWLINE_ANYCRLF
206 <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
207 </pre>
208 Those specifying line ending sequences are literal strings as shown, but the
209 letters can be in either case. This example sets multiline matching with CRLF
210 as the line ending sequence:
211 <pre>
212 /^abc/m&#60;crlf&#62;
213 </pre>
214 Details of the meanings of these PCRE options are given in the
215 <a href="pcreapi.html"><b>pcreapi</b></a>
216 documentation.
217 </P>
218 <br><b>
219 Finding all matches in a string
220 </b><br>
221 <P>
222 Searching for all possible matches within each subject string can be requested
223 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
224 again to search the remainder of the subject string. The difference between
225 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
226 <b>pcre_exec()</b> to start searching at a new point within the entire string
227 (which is in effect what Perl does), whereas the latter passes over a shortened
228 substring. This makes a difference to the matching process if the pattern
229 begins with a lookbehind assertion (including \b or \B).
230 </P>
231 <P>
232 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
233 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
234 flags set in order to search for another, non-empty, match at the same point.
235 If this second match fails, the start offset is advanced by one, and the normal
236 match is retried. This imitates the way Perl handles such cases when using the
237 <b>/g</b> modifier or the <b>split()</b> function.
238 </P>
239 <br><b>
240 Other modifiers
241 </b><br>
242 <P>
243 There are yet more modifiers for controlling the way <b>pcretest</b>
244 operates.
245 </P>
246 <P>
247 The <b>/+</b> modifier requests that as well as outputting the substring that
248 matched the entire pattern, pcretest should in addition output the remainder of
249 the subject string. This is useful for tests where the subject contains
250 multiple copies of the same substring.
251 </P>
252 <P>
253 The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
254 output a representation of the compiled byte code after compilation. Normally
255 this information contains length and offset values; however, if <b>/Z</b> is
256 also present, this data is replaced by spaces. This is a special feature for
257 use in the automatic test scripts; it ensures that the same output is generated
258 for different internal link sizes.
259 </P>
260 <P>
261 The <b>/L</b> modifier must be followed directly by the name of a locale, for
262 example,
263 <pre>
264 /pattern/Lfr_FR
265 </pre>
266 For this reason, it must be the last modifier. The given locale is set,
267 <b>pcre_maketables()</b> is called to build a set of character tables for the
268 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
269 regular expression. Without an <b>/L</b> modifier, NULL is passed as the tables
270 pointer; that is, <b>/L</b> applies only to the expression on which it appears.
271 </P>
272 <P>
273 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
274 compiled pattern (whether it is anchored, has a fixed first character, and
275 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
276 pattern. If the pattern is studied, the results of that are also output.
277 </P>
278 <P>
279 The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
280 <b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
281 </P>
282 <P>
283 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
284 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
285 facility is for testing the feature in PCRE that allows it to execute patterns
286 that were compiled on a host with a different endianness. This feature is not
287 available when the POSIX interface to PCRE is being used, that is, when the
288 <b>/P</b> pattern modifier is specified. See also the section about saving and
289 reloading compiled patterns below.
290 </P>
291 <P>
292 The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
293 expression has been compiled, and the results used when the expression is
294 matched.
295 </P>
296 <P>
297 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
298 pattern to be output.
299 </P>
300 <P>
301 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
302 API rather than its native API. When this is done, all other modifiers except
303 <b>/i</b>, <b>/m</b>, and <b>/+</b> are ignored. REG_ICASE is set if <b>/i</b> is
304 present, and REG_NEWLINE is set if <b>/m</b> is present. The wrapper functions
305 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
306 </P>
307 <P>
308 The <b>/8</b> modifier causes <b>pcretest</b> to call PCRE with the PCRE_UTF8
309 option set. This turns on support for UTF-8 character handling in PCRE,
310 provided that it was compiled with this support enabled. This modifier also
311 causes any non-printing characters in output strings to be printed using the
312 \x{hh...} notation if they are valid UTF-8 sequences.
313 </P>
314 <P>
315 If the <b>/?</b> modifier is used with <b>/8</b>, it causes <b>pcretest</b> to
316 call <b>pcre_compile()</b> with the PCRE_NO_UTF8_CHECK option, to suppress the
317 checking of the string for UTF-8 validity.
318 </P>
319 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
320 <P>
321 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
322 whitespace is removed, and it is then scanned for \ escapes. Some of these are
323 pretty esoteric features, intended for checking out some of the more
324 complicated features of PCRE. If you are just testing "ordinary" regular
325 expressions, you probably don't need any of these. The following escapes are
326 recognized:
327 <pre>
328 \a alarm (BEL, \x07)
329 \b backspace (\x08)
330 \e escape (\x27)
331 \f formfeed (\x0c)
332 \n newline (\x0a)
333 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
334 \r carriage return (\x0d)
335 \t tab (\x09)
336 \v vertical tab (\x0b)
337 \nnn octal character (up to 3 octal digits)
338 \xhh hexadecimal character (up to 2 hex digits)
339 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
340 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
341 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
342 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
343 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
344 ated by next non alphanumeric character)
345 \C+ show the current captured substrings at callout time
346 \C- do not supply a callout function
347 \C!n return 1 instead of 0 when callout number n is reached
348 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
349 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
350 \D use the <b>pcre_dfa_exec()</b> match function
351 \F only shortest match for <b>pcre_dfa_exec()</b>
352 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
353 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
354 ated by next non-alphanumeric character)
355 \L call pcre_get_substringlist() after a successful match
356 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
357 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
358 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
359 \P pass the PCRE_PARTIAL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
360 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
361 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
362 \S output details of memory get/free calls during matching
363 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
364 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
365 \&#62;dd start the match at offset dd (any number of digits);
366 this sets the <i>startoffset</i> argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
367 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
368 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
369 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
370 \&#60;anycrlf&#62; pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
371 \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
372 </pre>
373 The escapes that specify line ending sequences are literal strings, exactly as
374 shown. No more than one newline setting should be present in any data line.
375 </P>
376 <P>
377 A backslash followed by anything else just escapes the anything else. If
378 the very last character is a backslash, it is ignored. This gives a way of
379 passing an empty line as data, since a real empty line terminates the data
380 input.
381 </P>
382 <P>
383 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
384 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
385 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
386 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
387 <i>match_limit</i> number is a measure of the amount of backtracking that takes
388 place, and checking it out can be instructive. For most simple matches, the
389 number is quite small, but for patterns with very large numbers of matching
390 possibilities, it can become large very quickly with increasing length of
391 subject string. The <i>match_limit_recursion</i> number is a measure of how much
392 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
393 to complete the match attempt.
394 </P>
395 <P>
396 When \O is used, the value specified may be higher or lower than the size set
397 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
398 the call of <b>pcre_exec()</b> for the line in which it appears.
399 </P>
400 <P>
401 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
402 API to be used, the only option-setting sequences that have any effect are \B
403 and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
404 <b>regexec()</b>.
405 </P>
406 <P>
407 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
408 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
409 any number of hexadecimal digits inside the braces. The result is from one to
410 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
411 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
412 valid Unicode code points, or indeed valid UTF-8 characters according to the
413 later rules in RFC 3629.
414 </P>
415 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
416 <P>
417 By default, <b>pcretest</b> uses the standard PCRE matching function,
418 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
419 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
420 different way, and has some restrictions. The differences between the two
421 functions are described in the
422 <a href="pcrematching.html"><b>pcrematching</b></a>
423 documentation.
424 </P>
425 <P>
426 If a data line contains the \D escape sequence, or if the command line
427 contains the <b>-dfa</b> option, the alternative matching function is called.
428 This function finds all possible matches at a given point. If, however, the \F
429 escape sequence is present in the data line, it stops after the first match is
430 found. This is always the shortest possible match.
431 </P>
432 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
433 <P>
434 This section describes the output when the normal matching function,
435 <b>pcre_exec()</b>, is being used.
436 </P>
437 <P>
438 When a match succeeds, pcretest outputs the list of captured substrings that
439 <b>pcre_exec()</b> returns, starting with number 0 for the string that matched
440 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
441 when <b>pcre_exec()</b> returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
442 respectively, and otherwise the PCRE negative error number. Here is an example
443 of an interactive <b>pcretest</b> run.
444 <pre>
445 $ pcretest
446 PCRE version 7.0 30-Nov-2006
447
448 re&#62; /^abc(\d+)/
449 data&#62; abc123
450 0: abc123
451 1: 123
452 data&#62; xyz
453 No match
454 </pre>
455 If the strings contain any non-printing characters, they are output as \0x
456 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
457 pattern. See below for the definition of non-printing characters. If the
458 pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
459 the the rest of the subject string, identified by "0+" like this:
460 <pre>
461 re&#62; /cat/+
462 data&#62; cataract
463 0: cat
464 0+ aract
465 </pre>
466 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
467 matching attempts are output in sequence, like this:
468 <pre>
469 re&#62; /\Bi(\w\w)/g
470 data&#62; Mississippi
471 0: iss
472 1: ss
473 0: iss
474 1: ss
475 0: ipp
476 1: pp
477 </pre>
478 "No match" is output only if the first match attempt fails.
479 </P>
480 <P>
481 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
482 data line that is successfully matched, the substrings extracted by the
483 convenience functions are output with C, G, or L after the string number
484 instead of a colon. This is in addition to the normal full list. The string
485 length (that is, the return from the extraction function) is given in
486 parentheses after each string for <b>\C</b> and <b>\G</b>.
487 </P>
488 <P>
489 Note that whereas patterns can be continued over several lines (a plain "&#62;"
490 prompt is used for continuations), data lines may not. However newlines can be
491 included in data by means of the \n escape (or \r, \r\n, etc., depending on
492 the newline sequence setting).
493 </P>
494 <br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
495 <P>
496 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
497 means of the \D escape sequence or the <b>-dfa</b> command line option), the
498 output consists of a list of all the matches that start at the first point in
499 the subject where there is at least one match. For example:
500 <pre>
501 re&#62; /(tang|tangerine|tan)/
502 data&#62; yellow tangerine\D
503 0: tangerine
504 1: tang
505 2: tan
506 </pre>
507 (Using the normal matching function on this data finds only "tang".) The
508 longest matching string is always given first (and numbered zero).
509 </P>
510 <P>
511 If <b>/g</b> is present on the pattern, the search for further matches resumes
512 at the end of the longest match. For example:
513 <pre>
514 re&#62; /(tang|tangerine|tan)/g
515 data&#62; yellow tangerine and tangy sultana\D
516 0: tangerine
517 1: tang
518 2: tan
519 0: tang
520 1: tan
521 0: tan
522 </pre>
523 Since the matching function does not support substring capture, the escape
524 sequences that are concerned with captured substrings are not relevant.
525 </P>
526 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
527 <P>
528 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
529 indicating that the subject partially matched the pattern, you can restart the
530 match with additional subject data by means of the \R escape sequence. For
531 example:
532 <pre>
533 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
534 data&#62; 23ja\P\D
535 Partial match: 23ja
536 data&#62; n05\R\D
537 0: n05
538 </pre>
539 For further information about partial matching, see the
540 <a href="pcrepartial.html"><b>pcrepartial</b></a>
541 documentation.
542 </P>
543 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
544 <P>
545 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
546 is called during matching. This works with both matching functions. By default,
547 the called function displays the callout number, the start and current
548 positions in the text at the callout time, and the next pattern item to be
549 tested. For example, the output
550 <pre>
551 ---&#62;pqrabcdef
552 0 ^ ^ \d
553 </pre>
554 indicates that callout number 0 occurred for a match attempt starting at the
555 fourth character of the subject string, when the pointer was at the seventh
556 character of the data, and when the next pattern item was \d. Just one
557 circumflex is output if the start and current positions are the same.
558 </P>
559 <P>
560 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
561 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
562 callout number, the offset in the pattern, preceded by a plus, is output. For
563 example:
564 <pre>
565 re&#62; /\d?[A-E]\*/C
566 data&#62; E*
567 ---&#62;E*
568 +0 ^ \d?
569 +3 ^ [A-E]
570 +8 ^^ \*
571 +10 ^ ^
572 0: E*
573 </pre>
574 The callout function in <b>pcretest</b> returns zero (carry on matching) by
575 default, but you can use a \C item in a data line (as described above) to
576 change this.
577 </P>
578 <P>
579 Inserting callouts can be helpful when using <b>pcretest</b> to check
580 complicated regular expressions. For further information about callouts, see
581 the
582 <a href="pcrecallout.html"><b>pcrecallout</b></a>
583 documentation.
584 </P>
585 <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
586 <P>
587 When <b>pcretest</b> is outputting text in the compiled version of a pattern,
588 bytes other than 32-126 are always treated as non-printing characters are are
589 therefore shown as hex escapes.
590 </P>
591 <P>
592 When <b>pcretest</b> is outputting text that is a matched part of a subject
593 string, it behaves in the same way, unless a different locale has been set for
594 the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
595 function to distinguish printing and non-printing characters.
596 </P>
597 <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
598 <P>
599 The facilities described in this section are not available when the POSIX
600 inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
601 specified.
602 </P>
603 <P>
604 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
605 compiled pattern to a file, by following the modifiers with &#62; and a file name.
606 For example:
607 <pre>
608 /pattern/im &#62;/some/file
609 </pre>
610 See the
611 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
612 documentation for a discussion about saving and re-using compiled patterns.
613 </P>
614 <P>
615 The data that is written is binary. The first eight bytes are the length of the
616 compiled pattern data followed by the length of the optional study data, each
617 written as four bytes in big-endian order (most significant byte first). If
618 there is no study data (either the pattern was not studied, or studying did not
619 return any data), the second length is zero. The lengths are followed by an
620 exact copy of the compiled pattern. If there is additional study data, this
621 follows immediately after the compiled pattern. After writing the file,
622 <b>pcretest</b> expects to read a new pattern.
623 </P>
624 <P>
625 A saved pattern can be reloaded into <b>pcretest</b> by specifing &#60; and a file
626 name instead of a pattern. The name of the file must not contain a &#60; character,
627 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
628 characters.
629 For example:
630 <pre>
631 re&#62; &#60;/some/file
632 Compiled regex loaded from /some/file
633 No study data
634 </pre>
635 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
636 the usual way.
637 </P>
638 <P>
639 You can copy a file written by <b>pcretest</b> to a different host and reload it
640 there, even if the new host has opposite endianness to the one on which the
641 pattern was compiled. For example, you can compile on an i86 machine and run on
642 a SPARC machine.
643 </P>
644 <P>
645 File names for saving and reloading can be absolute or relative, but note that
646 the shell facility of expanding a file name that starts with a tilde (~) is not
647 available.
648 </P>
649 <P>
650 The ability to save and reload files in <b>pcretest</b> is intended for testing
651 and experimentation. It is not intended for production use because only a
652 single pattern can be written to a file. Furthermore, there is no facility for
653 supplying custom character tables for use with a reloaded pattern. If the
654 original pattern was compiled with custom tables, an attempt to match a subject
655 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
656 Finally, if you attempt to load a file that is not in the correct format, the
657 result is undefined.
658 </P>
659 <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
660 <P>
661 <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
662 <b>pcrepartial</b>(d), <b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
663 </P>
664 <br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
665 <P>
666 Philip Hazel
667 <br>
668 University Computing Service
669 <br>
670 Cambridge CB2 3QH, England.
671 <br>
672 </P>
673 <br><a name="SEC15" href="#TOC1">REVISION</a><br>
674 <P>
675 Last updated: 21 August 2007
676 <br>
677 Copyright &copy; 1997-2007 University of Cambridge.
678 <br>
679 <p>
680 Return to the <a href="index.html">PCRE index page</a>.
681 </p>

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