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Revision 512 - (show annotations)
Tue Mar 30 11:11:52 2010 UTC (11 years, 3 months ago) by ph10
File size: 29724 byte(s)
Fix compile problems when heap is in use
3 pcretest - a program for testing Perl-compatible regular expressions.
5 .rs
6 .sp
7 .B pcretest "[options] [source] [destination]"
8 .sp
9 \fBpcretest\fP was written as a test program for the PCRE regular expression
10 library itself, but it can also be used for experimenting with regular
11 expressions. This document describes the features of the test program; for
12 details of the regular expressions themselves, see the
13 .\" HREF
14 \fBpcrepattern\fP
15 .\"
16 documentation. For details of the PCRE library function calls and their
17 options, see the
18 .\" HREF
19 \fBpcreapi\fP
20 .\"
21 documentation.
22 .
23 .
25 .rs
26 .TP 10
27 \fB-b\fP
28 Behave as if each regex has the \fB/B\fP (show bytecode) modifier; the internal
29 form is output after compilation.
30 .TP 10
31 \fB-C\fP
32 Output the version number of the PCRE library, and all available information
33 about the optional features that are included, and then exit.
34 .TP 10
35 \fB-d\fP
36 Behave as if each regex has the \fB/D\fP (debug) modifier; the internal
37 form and information about the compiled pattern is output after compilation;
38 \fB-d\fP is equivalent to \fB-b -i\fP.
39 .TP 10
40 \fB-dfa\fP
41 Behave as if each data line contains the \eD escape sequence; this causes the
42 alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the
43 standard \fBpcre_exec()\fP function (more detail is given below).
44 .TP 10
45 \fB-help\fP
46 Output a brief summary these options and then exit.
47 .TP 10
48 \fB-i\fP
49 Behave as if each regex has the \fB/I\fP modifier; information about the
50 compiled pattern is given after compilation.
51 .TP 10
52 \fB-M\fP
53 Behave as if each data line contains the \eM escape sequence; this causes
54 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
55 calling \fBpcre_exec()\fP repeatedly with different limits.
56 .TP 10
57 \fB-m\fP
58 Output the size of each compiled pattern after it has been compiled. This is
59 equivalent to adding \fB/M\fP to each regular expression. For compatibility
60 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
61 .TP 10
62 \fB-o\fP \fIosize\fP
63 Set the number of elements in the output vector that is used when calling
64 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
65 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
66 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
67 changed for individual matching calls by including \eO in the data line (see
68 below).
69 .TP 10
70 \fB-p\fP
71 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
72 used to call PCRE. None of the other options has any effect when \fB-p\fP is
73 set.
74 .TP 10
75 \fB-q\fP
76 Do not output the version number of \fBpcretest\fP at the start of execution.
77 .TP 10
78 \fB-S\fP \fIsize\fP
79 On Unix-like systems, set the size of the runtime stack to \fIsize\fP
80 megabytes.
81 .TP 10
82 \fB-t\fP
83 Run each compile, study, and match many times with a timer, and output
84 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
85 \fB-t\fP, because you will then get the size output a zillion times, and the
86 timing will be distorted. You can control the number of iterations that are
87 used for timing by following \fB-t\fP with a number (as a separate item on the
88 command line). For example, "-t 1000" would iterate 1000 times. The default is
89 to iterate 500000 times.
90 .TP 10
91 \fB-tm\fP
92 This is like \fB-t\fP except that it times only the matching phase, not the
93 compile or study phases.
94 .
95 .
97 .rs
98 .sp
99 If \fBpcretest\fP is given two filename arguments, it reads from the first and
100 writes to the second. If it is given only one filename argument, it reads from
101 that file and writes to stdout. Otherwise, it reads from stdin and writes to
102 stdout, and prompts for each line of input, using "re>" to prompt for regular
103 expressions, and "data>" to prompt for data lines.
104 .P
105 When \fBpcretest\fP is built, a configuration option can specify that it should
106 be linked with the \fBlibreadline\fP library. When this is done, if the input
107 is from a terminal, it is read using the \fBreadline()\fP function. This
108 provides line-editing and history facilities. The output from the \fB-help\fP
109 option states whether or not \fBreadline()\fP will be used.
110 .P
111 The program handles any number of sets of input on a single input file. Each
112 set starts with a regular expression, and continues with any number of data
113 lines to be matched against the pattern.
114 .P
115 Each data line is matched separately and independently. If you want to do
116 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
117 etc., depending on the newline setting) in a single line of input to encode the
118 newline sequences. There is no limit on the length of data lines; the input
119 buffer is automatically extended if it is too small.
120 .P
121 An empty line signals the end of the data lines, at which point a new regular
122 expression is read. The regular expressions are given enclosed in any
123 non-alphanumeric delimiters other than backslash, for example:
124 .sp
125 /(a|bc)x+yz/
126 .sp
127 White space before the initial delimiter is ignored. A regular expression may
128 be continued over several input lines, in which case the newline characters are
129 included within it. It is possible to include the delimiter within the pattern
130 by escaping it, for example
131 .sp
132 /abc\e/def/
133 .sp
134 If you do so, the escape and the delimiter form part of the pattern, but since
135 delimiters are always non-alphanumeric, this does not affect its interpretation.
136 If the terminating delimiter is immediately followed by a backslash, for
137 example,
138 .sp
139 /abc/\e
140 .sp
141 then a backslash is added to the end of the pattern. This is done to provide a
142 way of testing the error condition that arises if a pattern finishes with a
143 backslash, because
144 .sp
145 /abc\e/
146 .sp
147 is interpreted as the first line of a pattern that starts with "abc/", causing
148 pcretest to read the next line as a continuation of the regular expression.
149 .
150 .
152 .rs
153 .sp
154 A pattern may be followed by any number of modifiers, which are mostly single
155 characters. Following Perl usage, these are referred to below as, for example,
156 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
157 always be a slash, and no slash is used when writing modifiers. Whitespace may
158 appear between the final pattern delimiter and the first modifier, and between
159 the modifiers themselves.
160 .P
161 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
162 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
163 \fBpcre_compile()\fP is called. These four modifier letters have the same
164 effect as they do in Perl. For example:
165 .sp
166 /caseless/i
167 .sp
168 The following table shows additional modifiers for setting PCRE options that do
169 not correspond to anything in Perl:
170 .sp
180 \fB/<cr>\fP PCRE_NEWLINE_CR
181 \fB/<lf>\fP PCRE_NEWLINE_LF
182 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
183 \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
184 \fB/<any>\fP PCRE_NEWLINE_ANY
185 \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
186 \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
187 .sp
188 Those specifying line ending sequences are literal strings as shown, but the
189 letters can be in either case. This example sets multiline matching with CRLF
190 as the line ending sequence:
191 .sp
192 /^abc/m<crlf>
193 .sp
194 Details of the meanings of these PCRE options are given in the
195 .\" HREF
196 \fBpcreapi\fP
197 .\"
198 documentation.
199 .
200 .
201 .SS "Finding all matches in a string"
202 .rs
203 .sp
204 Searching for all possible matches within each subject string can be requested
205 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
206 again to search the remainder of the subject string. The difference between
207 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
208 \fBpcre_exec()\fP to start searching at a new point within the entire string
209 (which is in effect what Perl does), whereas the latter passes over a shortened
210 substring. This makes a difference to the matching process if the pattern
211 begins with a lookbehind assertion (including \eb or \eB).
212 .P
213 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
214 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
215 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
216 same point. If this second match fails, the start offset is advanced by one
217 character, and the normal match is retried. This imitates the way Perl handles
218 such cases when using the \fB/g\fP modifier or the \fBsplit()\fP function.
219 .
220 .
221 .SS "Other modifiers"
222 .rs
223 .sp
224 There are yet more modifiers for controlling the way \fBpcretest\fP
225 operates.
226 .P
227 The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
228 option set. This turns on support for UTF-8 character handling in PCRE,
229 provided that it was compiled with this support enabled. This modifier also
230 causes any non-printing characters in output strings to be printed using the
231 \ex{hh...} notation if they are valid UTF-8 sequences.
232 .P
233 If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
234 call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
235 checking of the string for UTF-8 validity.
236 .P
237 The \fB/+\fP modifier requests that as well as outputting the substring that
238 matched the entire pattern, pcretest should in addition output the remainder of
239 the subject string. This is useful for tests where the subject contains
240 multiple copies of the same substring.
241 .P
242 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
243 output a representation of the compiled byte code after compilation. Normally
244 this information contains length and offset values; however, if \fB/Z\fP is
245 also present, this data is replaced by spaces. This is a special feature for
246 use in the automatic test scripts; it ensures that the same output is generated
247 for different internal link sizes.
248 .P
249 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
250 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
251 .P
252 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
253 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
254 facility is for testing the feature in PCRE that allows it to execute patterns
255 that were compiled on a host with a different endianness. This feature is not
256 available when the POSIX interface to PCRE is being used, that is, when the
257 \fB/P\fP pattern modifier is specified. See also the section about saving and
258 reloading compiled patterns below.
259 .P
260 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
261 compiled pattern (whether it is anchored, has a fixed first character, and
262 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
263 pattern. If the pattern is studied, the results of that are also output.
264 .P
265 The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking
266 control verbs that are returned from calls to \fBpcre_exec()\fP. It causes
267 \fBpcretest\fP to create a \fBpcre_extra\fP block if one has not already been
268 created by a call to \fBpcre_study()\fP, and to set the PCRE_EXTRA_MARK flag
269 and the \fBmark\fP field within it, every time that \fBpcre_exec()\fP is
270 called. If the variable that the \fBmark\fP field points to is non-NULL for a
271 match, non-match, or partial match, \fBpcretest\fP prints the string to which
272 it points. For a match, this is shown on a line by itself, tagged with "MK:".
273 For a non-match it is added to the message.
274 .P
275 The \fB/L\fP modifier must be followed directly by the name of a locale, for
276 example,
277 .sp
278 /pattern/Lfr_FR
279 .sp
280 For this reason, it must be the last modifier. The given locale is set,
281 \fBpcre_maketables()\fP is called to build a set of character tables for the
282 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
283 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
284 pointer; that is, \fB/L\fP applies only to the expression on which it appears.
285 .P
286 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
287 pattern to be output.
288 .P
289 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
290 API rather than its native API. When this is done, all other modifiers except
291 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
292 present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
293 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
294 .P
295 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
296 expression has been compiled, and the results used when the expression is
297 matched.
298 .
299 .
301 .rs
302 .sp
303 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
304 whitespace is removed, and it is then scanned for \e escapes. Some of these are
305 pretty esoteric features, intended for checking out some of the more
306 complicated features of PCRE. If you are just testing "ordinary" regular
307 expressions, you probably don't need any of these. The following escapes are
308 recognized:
309 .sp
310 \ea alarm (BEL, \ex07)
311 \eb backspace (\ex08)
312 \ee escape (\ex27)
313 \ef formfeed (\ex0c)
314 \en newline (\ex0a)
315 .\" JOIN
316 \eqdd set the PCRE_MATCH_LIMIT limit to dd
317 (any number of digits)
318 \er carriage return (\ex0d)
319 \et tab (\ex09)
320 \ev vertical tab (\ex0b)
321 \ennn octal character (up to 3 octal digits)
322 \exhh hexadecimal character (up to 2 hex digits)
323 .\" JOIN
324 \ex{hh...} hexadecimal character, any number of digits
325 in UTF-8 mode
326 .\" JOIN
327 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
328 or \fBpcre_dfa_exec()\fP
329 .\" JOIN
330 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
331 or \fBpcre_dfa_exec()\fP
332 .\" JOIN
333 \eCdd call pcre_copy_substring() for substring dd
334 after a successful match (number less than 32)
335 .\" JOIN
336 \eCname call pcre_copy_named_substring() for substring
337 "name" after a successful match (name termin-
338 ated by next non alphanumeric character)
339 .\" JOIN
340 \eC+ show the current captured substrings at callout
341 time
342 \eC- do not supply a callout function
343 .\" JOIN
344 \eC!n return 1 instead of 0 when callout number n is
345 reached
346 .\" JOIN
347 \eC!n!m return 1 instead of 0 when callout number n is
348 reached for the nth time
349 .\" JOIN
350 \eC*n pass the number n (may be negative) as callout
351 data; this is used as the callout return value
352 \eD use the \fBpcre_dfa_exec()\fP match function
353 \eF only shortest match for \fBpcre_dfa_exec()\fP
354 .\" JOIN
355 \eGdd call pcre_get_substring() for substring dd
356 after a successful match (number less than 32)
357 .\" JOIN
358 \eGname call pcre_get_named_substring() for substring
359 "name" after a successful match (name termin-
360 ated by next non-alphanumeric character)
361 .\" JOIN
362 \eL call pcre_get_substringlist() after a
363 successful match
364 .\" JOIN
365 \eM discover the minimum MATCH_LIMIT and
367 .\" JOIN
368 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
369 or \fBpcre_dfa_exec()\fP; if used twice, pass the
371 .\" JOIN
372 \eOdd set the size of the output vector passed to
373 \fBpcre_exec()\fP to dd (any number of digits)
374 .\" JOIN
375 \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP
376 or \fBpcre_dfa_exec()\fP; if used twice, pass the
378 .\" JOIN
379 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
380 (any number of digits)
381 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
382 \eS output details of memory get/free calls during matching
383 .\" JOIN
384 \eY pass the PCRE_NO_START_OPTIMIZE option to \fBpcre_exec()\fP
385 or \fBpcre_dfa_exec()\fP
386 .\" JOIN
387 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
388 or \fBpcre_dfa_exec()\fP
389 .\" JOIN
390 \e? pass the PCRE_NO_UTF8_CHECK option to
391 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
392 \e>dd start the match at offset dd (any number of digits);
393 .\" JOIN
394 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
395 or \fBpcre_dfa_exec()\fP
396 .\" JOIN
397 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
398 or \fBpcre_dfa_exec()\fP
399 .\" JOIN
400 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
401 or \fBpcre_dfa_exec()\fP
402 .\" JOIN
403 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
404 or \fBpcre_dfa_exec()\fP
405 .\" JOIN
406 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
407 or \fBpcre_dfa_exec()\fP
408 .\" JOIN
409 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
410 or \fBpcre_dfa_exec()\fP
411 .sp
412 The escapes that specify line ending sequences are literal strings, exactly as
413 shown. No more than one newline setting should be present in any data line.
414 .P
415 A backslash followed by anything else just escapes the anything else. If
416 the very last character is a backslash, it is ignored. This gives a way of
417 passing an empty line as data, since a real empty line terminates the data
418 input.
419 .P
420 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
421 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
422 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
423 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
424 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
425 place, and checking it out can be instructive. For most simple matches, the
426 number is quite small, but for patterns with very large numbers of matching
427 possibilities, it can become large very quickly with increasing length of
428 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
429 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
430 to complete the match attempt.
431 .P
432 When \eO is used, the value specified may be higher or lower than the size set
433 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
434 the call of \fBpcre_exec()\fP for the line in which it appears.
435 .P
436 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
437 API to be used, the only option-setting sequences that have any effect are \eB
438 and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
439 \fBregexec()\fP.
440 .P
441 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
442 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
443 any number of hexadecimal digits inside the braces. The result is from one to
444 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
445 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
446 valid Unicode code points, or indeed valid UTF-8 characters according to the
447 later rules in RFC 3629.
448 .
449 .
451 .rs
452 .sp
453 By default, \fBpcretest\fP uses the standard PCRE matching function,
454 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
455 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
456 different way, and has some restrictions. The differences between the two
457 functions are described in the
458 .\" HREF
459 \fBpcrematching\fP
460 .\"
461 documentation.
462 .P
463 If a data line contains the \eD escape sequence, or if the command line
464 contains the \fB-dfa\fP option, the alternative matching function is called.
465 This function finds all possible matches at a given point. If, however, the \eF
466 escape sequence is present in the data line, it stops after the first match is
467 found. This is always the shortest possible match.
468 .
469 .
471 .rs
472 .sp
473 This section describes the output when the normal matching function,
474 \fBpcre_exec()\fP, is being used.
475 .P
476 When a match succeeds, pcretest outputs the list of captured substrings that
477 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
478 the whole pattern. Otherwise, it outputs "No match" when the return is
479 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
480 substring when \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL. For any other
481 returns, it outputs the PCRE negative error number. Here is an example of an
482 interactive \fBpcretest\fP run.
483 .sp
484 $ pcretest
485 PCRE version 7.0 30-Nov-2006
486 .sp
487 re> /^abc(\ed+)/
488 data> abc123
489 0: abc123
490 1: 123
491 data> xyz
492 No match
493 .sp
494 Note that unset capturing substrings that are not followed by one that is set
495 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
496 the following example, there are two capturing substrings, but when the first
497 data line is matched, the second, unset substring is not shown. An "internal"
498 unset substring is shown as "<unset>", as for the second data line.
499 .sp
500 re> /(a)|(b)/
501 data> a
502 0: a
503 1: a
504 data> b
505 0: b
506 1: <unset>
507 2: b
508 .sp
509 If the strings contain any non-printing characters, they are output as \e0x
510 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
511 pattern. See below for the definition of non-printing characters. If the
512 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
513 the the rest of the subject string, identified by "0+" like this:
514 .sp
515 re> /cat/+
516 data> cataract
517 0: cat
518 0+ aract
519 .sp
520 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
521 matching attempts are output in sequence, like this:
522 .sp
523 re> /\eBi(\ew\ew)/g
524 data> Mississippi
525 0: iss
526 1: ss
527 0: iss
528 1: ss
529 0: ipp
530 1: pp
531 .sp
532 "No match" is output only if the first match attempt fails.
533 .P
534 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
535 data line that is successfully matched, the substrings extracted by the
536 convenience functions are output with C, G, or L after the string number
537 instead of a colon. This is in addition to the normal full list. The string
538 length (that is, the return from the extraction function) is given in
539 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
540 .P
541 Note that whereas patterns can be continued over several lines (a plain ">"
542 prompt is used for continuations), data lines may not. However newlines can be
543 included in data by means of the \en escape (or \er, \er\en, etc., depending on
544 the newline sequence setting).
545 .
546 .
547 .
549 .rs
550 .sp
551 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
552 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
553 output consists of a list of all the matches that start at the first point in
554 the subject where there is at least one match. For example:
555 .sp
556 re> /(tang|tangerine|tan)/
557 data> yellow tangerine\eD
558 0: tangerine
559 1: tang
560 2: tan
561 .sp
562 (Using the normal matching function on this data finds only "tang".) The
563 longest matching string is always given first (and numbered zero). After a
564 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
565 partially matching substring.
566 .P
567 If \fB/g\fP is present on the pattern, the search for further matches resumes
568 at the end of the longest match. For example:
569 .sp
570 re> /(tang|tangerine|tan)/g
571 data> yellow tangerine and tangy sultana\eD
572 0: tangerine
573 1: tang
574 2: tan
575 0: tang
576 1: tan
577 0: tan
578 .sp
579 Since the matching function does not support substring capture, the escape
580 sequences that are concerned with captured substrings are not relevant.
581 .
582 .
584 .rs
585 .sp
586 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
587 indicating that the subject partially matched the pattern, you can restart the
588 match with additional subject data by means of the \eR escape sequence. For
589 example:
590 .sp
591 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
592 data> 23ja\eP\eD
593 Partial match: 23ja
594 data> n05\eR\eD
595 0: n05
596 .sp
597 For further information about partial matching, see the
598 .\" HREF
599 \fBpcrepartial\fP
600 .\"
601 documentation.
602 .
603 .
605 .rs
606 .sp
607 If the pattern contains any callout requests, \fBpcretest\fP's callout function
608 is called during matching. This works with both matching functions. By default,
609 the called function displays the callout number, the start and current
610 positions in the text at the callout time, and the next pattern item to be
611 tested. For example, the output
612 .sp
613 --->pqrabcdef
614 0 ^ ^ \ed
615 .sp
616 indicates that callout number 0 occurred for a match attempt starting at the
617 fourth character of the subject string, when the pointer was at the seventh
618 character of the data, and when the next pattern item was \ed. Just one
619 circumflex is output if the start and current positions are the same.
620 .P
621 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
622 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
623 callout number, the offset in the pattern, preceded by a plus, is output. For
624 example:
625 .sp
626 re> /\ed?[A-E]\e*/C
627 data> E*
628 --->E*
629 +0 ^ \ed?
630 +3 ^ [A-E]
631 +8 ^^ \e*
632 +10 ^ ^
633 0: E*
634 .sp
635 The callout function in \fBpcretest\fP returns zero (carry on matching) by
636 default, but you can use a \eC item in a data line (as described above) to
637 change this.
638 .P
639 Inserting callouts can be helpful when using \fBpcretest\fP to check
640 complicated regular expressions. For further information about callouts, see
641 the
642 .\" HREF
643 \fBpcrecallout\fP
644 .\"
645 documentation.
646 .
647 .
648 .
650 .rs
651 .sp
652 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
653 bytes other than 32-126 are always treated as non-printing characters are are
654 therefore shown as hex escapes.
655 .P
656 When \fBpcretest\fP is outputting text that is a matched part of a subject
657 string, it behaves in the same way, unless a different locale has been set for
658 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
659 function to distinguish printing and non-printing characters.
660 .
661 .
662 .
664 .rs
665 .sp
666 The facilities described in this section are not available when the POSIX
667 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
668 specified.
669 .P
670 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
671 compiled pattern to a file, by following the modifiers with > and a file name.
672 For example:
673 .sp
674 /pattern/im >/some/file
675 .sp
676 See the
677 .\" HREF
678 \fBpcreprecompile\fP
679 .\"
680 documentation for a discussion about saving and re-using compiled patterns.
681 .P
682 The data that is written is binary. The first eight bytes are the length of the
683 compiled pattern data followed by the length of the optional study data, each
684 written as four bytes in big-endian order (most significant byte first). If
685 there is no study data (either the pattern was not studied, or studying did not
686 return any data), the second length is zero. The lengths are followed by an
687 exact copy of the compiled pattern. If there is additional study data, this
688 follows immediately after the compiled pattern. After writing the file,
689 \fBpcretest\fP expects to read a new pattern.
690 .P
691 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
692 name instead of a pattern. The name of the file must not contain a < character,
693 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
694 characters.
695 For example:
696 .sp
697 re> </some/file
698 Compiled regex loaded from /some/file
699 No study data
700 .sp
701 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
702 the usual way.
703 .P
704 You can copy a file written by \fBpcretest\fP to a different host and reload it
705 there, even if the new host has opposite endianness to the one on which the
706 pattern was compiled. For example, you can compile on an i86 machine and run on
707 a SPARC machine.
708 .P
709 File names for saving and reloading can be absolute or relative, but note that
710 the shell facility of expanding a file name that starts with a tilde (~) is not
711 available.
712 .P
713 The ability to save and reload files in \fBpcretest\fP is intended for testing
714 and experimentation. It is not intended for production use because only a
715 single pattern can be written to a file. Furthermore, there is no facility for
716 supplying custom character tables for use with a reloaded pattern. If the
717 original pattern was compiled with custom tables, an attempt to match a subject
718 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
719 Finally, if you attempt to load a file that is not in the correct format, the
720 result is undefined.
721 .
722 .
723 .SH "SEE ALSO"
724 .rs
725 .sp
726 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
727 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
728 .
729 .
731 .rs
732 .sp
733 .nf
734 Philip Hazel
735 University Computing Service
736 Cambridge CB2 3QH, England.
737 .fi
738 .
739 .
741 .rs
742 .sp
743 .nf
744 Last updated: 26 March 2010
745 Copyright (c) 1997-2010 University of Cambridge.
746 .fi


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