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Revision 541 - (show annotations)
Mon Jun 14 15:19:33 2010 UTC (11 years, 4 months ago) by ph10
File size: 30245 byte(s)
Add /T option to pcretest and additional tests with non-standard tables.
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 compile-time
169 options that do not correspond to anything in Perl:
170 .sp
171 \fB/8\fP PCRE_UTF8
180 \fB/W\fP PCRE_UCP
183 \fB/<cr>\fP PCRE_NEWLINE_CR
184 \fB/<lf>\fP PCRE_NEWLINE_LF
185 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
186 \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
187 \fB/<any>\fP PCRE_NEWLINE_ANY
188 \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
189 \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
190 .sp
191 The modifiers that are enclosed in angle brackets are literal strings as shown,
192 including the angle brackets, but the letters can be in either case. This
193 example sets multiline matching with CRLF as the line ending sequence:
194 .sp
195 /^abc/m<crlf>
196 .sp
197 As well as turning on the PCRE_UTF8 option, the \fB/8\fP modifier also causes
198 any non-printing characters in output strings to be printed using the
199 \ex{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
200 options are given in the
201 .\" HREF
202 \fBpcreapi\fP
203 .\"
204 documentation.
205 .
206 .
207 .SS "Finding all matches in a string"
208 .rs
209 .sp
210 Searching for all possible matches within each subject string can be requested
211 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
212 again to search the remainder of the subject string. The difference between
213 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
214 \fBpcre_exec()\fP to start searching at a new point within the entire string
215 (which is in effect what Perl does), whereas the latter passes over a shortened
216 substring. This makes a difference to the matching process if the pattern
217 begins with a lookbehind assertion (including \eb or \eB).
218 .P
219 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
220 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
221 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
222 same point. If this second match fails, the start offset is advanced by one
223 character, and the normal match is retried. This imitates the way Perl handles
224 such cases when using the \fB/g\fP modifier or the \fBsplit()\fP function.
225 .
226 .
227 .SS "Other modifiers"
228 .rs
229 .sp
230 There are yet more modifiers for controlling the way \fBpcretest\fP
231 operates.
232 .P
233 The \fB/+\fP modifier requests that as well as outputting the substring that
234 matched the entire pattern, pcretest should in addition output the remainder of
235 the subject string. This is useful for tests where the subject contains
236 multiple copies of the same substring.
237 .P
238 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
239 output a representation of the compiled byte code after compilation. Normally
240 this information contains length and offset values; however, if \fB/Z\fP is
241 also present, this data is replaced by spaces. This is a special feature for
242 use in the automatic test scripts; it ensures that the same output is generated
243 for different internal link sizes.
244 .P
245 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
246 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
247 .P
248 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
249 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
250 facility is for testing the feature in PCRE that allows it to execute patterns
251 that were compiled on a host with a different endianness. This feature is not
252 available when the POSIX interface to PCRE is being used, that is, when the
253 \fB/P\fP pattern modifier is specified. See also the section about saving and
254 reloading compiled patterns below.
255 .P
256 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
257 compiled pattern (whether it is anchored, has a fixed first character, and
258 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
259 pattern. If the pattern is studied, the results of that are also output.
260 .P
261 The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking
262 control verbs that are returned from calls to \fBpcre_exec()\fP. It causes
263 \fBpcretest\fP to create a \fBpcre_extra\fP block if one has not already been
264 created by a call to \fBpcre_study()\fP, and to set the PCRE_EXTRA_MARK flag
265 and the \fBmark\fP field within it, every time that \fBpcre_exec()\fP is
266 called. If the variable that the \fBmark\fP field points to is non-NULL for a
267 match, non-match, or partial match, \fBpcretest\fP prints the string to which
268 it points. For a match, this is shown on a line by itself, tagged with "MK:".
269 For a non-match it is added to the message.
270 .P
271 The \fB/L\fP modifier must be followed directly by the name of a locale, for
272 example,
273 .sp
274 /pattern/Lfr_FR
275 .sp
276 For this reason, it must be the last modifier. The given locale is set,
277 \fBpcre_maketables()\fP is called to build a set of character tables for the
278 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
279 regular expression. Without an \fB/L\fP (or \fB/T\fP) modifier, NULL is passed
280 as the tables pointer; that is, \fB/L\fP applies only to the expression on
281 which it appears.
282 .P
283 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
284 pattern to be output.
285 .P
286 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
287 expression has been compiled, and the results used when the expression is
288 matched.
289 .P
290 The \fB/T\fP modifier must be followed by a single digit. It causes a specific
291 set of built-in character tables to be passed to \fBpcre_compile()\fP. It is
292 used in the standard PCRE tests to check behaviour with different character
293 tables. The digit specifies the tables as follows:
294 .sp
295 0 the default ASCII tables, as distributed in
296 pcre_chartables.c.dist
297 1 a set of tables defining ISO 8859 characters
298 .sp
299 In table 1, some characters whose codes are greater than 128 are identified as
300 letters, digits, spaces, etc.
301 .
302 .
303 .SS "Using the POSIX wrapper API"
304 .rs
305 .sp
306 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
307 API rather than its native API. When \fB/P\fP is set, the following modifiers
308 set options for the \fBregcomp()\fP function:
309 .sp
310 /i REG_ICASE
313 /s REG_DOTALL )
314 /U REG_UNGREEDY ) These options are not part of
315 /W REG_UCP ) the POSIX standard
316 /8 REG_UTF8 )
317 .sp
318 The \fB/+\fP modifier works as described above. All other modifiers are
319 ignored.
320 .
321 .
323 .rs
324 .sp
325 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
326 whitespace is removed, and it is then scanned for \e escapes. Some of these are
327 pretty esoteric features, intended for checking out some of the more
328 complicated features of PCRE. If you are just testing "ordinary" regular
329 expressions, you probably don't need any of these. The following escapes are
330 recognized:
331 .sp
332 \ea alarm (BEL, \ex07)
333 \eb backspace (\ex08)
334 \ee escape (\ex27)
335 \ef formfeed (\ex0c)
336 \en newline (\ex0a)
337 .\" JOIN
338 \eqdd set the PCRE_MATCH_LIMIT limit to dd
339 (any number of digits)
340 \er carriage return (\ex0d)
341 \et tab (\ex09)
342 \ev vertical tab (\ex0b)
343 \ennn octal character (up to 3 octal digits)
344 \exhh hexadecimal character (up to 2 hex digits)
345 .\" JOIN
346 \ex{hh...} hexadecimal character, any number of digits
347 in UTF-8 mode
348 .\" JOIN
349 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
350 or \fBpcre_dfa_exec()\fP
351 .\" JOIN
352 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
353 or \fBpcre_dfa_exec()\fP
354 .\" JOIN
355 \eCdd call pcre_copy_substring() for substring dd
356 after a successful match (number less than 32)
357 .\" JOIN
358 \eCname call pcre_copy_named_substring() for substring
359 "name" after a successful match (name termin-
360 ated by next non alphanumeric character)
361 .\" JOIN
362 \eC+ show the current captured substrings at callout
363 time
364 \eC- do not supply a callout function
365 .\" JOIN
366 \eC!n return 1 instead of 0 when callout number n is
367 reached
368 .\" JOIN
369 \eC!n!m return 1 instead of 0 when callout number n is
370 reached for the nth time
371 .\" JOIN
372 \eC*n pass the number n (may be negative) as callout
373 data; this is used as the callout return value
374 \eD use the \fBpcre_dfa_exec()\fP match function
375 \eF only shortest match for \fBpcre_dfa_exec()\fP
376 .\" JOIN
377 \eGdd call pcre_get_substring() for substring dd
378 after a successful match (number less than 32)
379 .\" JOIN
380 \eGname call pcre_get_named_substring() for substring
381 "name" after a successful match (name termin-
382 ated by next non-alphanumeric character)
383 .\" JOIN
384 \eL call pcre_get_substringlist() after a
385 successful match
386 .\" JOIN
387 \eM discover the minimum MATCH_LIMIT and
389 .\" JOIN
390 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
391 or \fBpcre_dfa_exec()\fP; if used twice, pass the
393 .\" JOIN
394 \eOdd set the size of the output vector passed to
395 \fBpcre_exec()\fP to dd (any number of digits)
396 .\" JOIN
397 \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP
398 or \fBpcre_dfa_exec()\fP; if used twice, pass the
400 .\" JOIN
401 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
402 (any number of digits)
403 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
404 \eS output details of memory get/free calls during matching
405 .\" JOIN
406 \eY pass the PCRE_NO_START_OPTIMIZE option to \fBpcre_exec()\fP
407 or \fBpcre_dfa_exec()\fP
408 .\" JOIN
409 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
410 or \fBpcre_dfa_exec()\fP
411 .\" JOIN
412 \e? pass the PCRE_NO_UTF8_CHECK option to
413 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
414 \e>dd start the match at offset dd (any number of digits);
415 .\" JOIN
416 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
417 or \fBpcre_dfa_exec()\fP
418 .\" JOIN
419 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
420 or \fBpcre_dfa_exec()\fP
421 .\" JOIN
422 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
423 or \fBpcre_dfa_exec()\fP
424 .\" JOIN
425 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
426 or \fBpcre_dfa_exec()\fP
427 .\" JOIN
428 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
429 or \fBpcre_dfa_exec()\fP
430 .\" JOIN
431 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
432 or \fBpcre_dfa_exec()\fP
433 .sp
434 The escapes that specify line ending sequences are literal strings, exactly as
435 shown. No more than one newline setting should be present in any data line.
436 .P
437 A backslash followed by anything else just escapes the anything else. If
438 the very last character is a backslash, it is ignored. This gives a way of
439 passing an empty line as data, since a real empty line terminates the data
440 input.
441 .P
442 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
443 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
444 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
445 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
446 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
447 place, and checking it out can be instructive. For most simple matches, the
448 number is quite small, but for patterns with very large numbers of matching
449 possibilities, it can become large very quickly with increasing length of
450 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
451 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
452 to complete the match attempt.
453 .P
454 When \eO is used, the value specified may be higher or lower than the size set
455 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
456 the call of \fBpcre_exec()\fP for the line in which it appears.
457 .P
458 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
459 API to be used, the only option-setting sequences that have any effect are \eB,
460 \eN, and \eZ, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
461 to be passed to \fBregexec()\fP.
462 .P
463 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
464 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
465 any number of hexadecimal digits inside the braces. The result is from one to
466 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
467 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
468 valid Unicode code points, or indeed valid UTF-8 characters according to the
469 later rules in RFC 3629.
470 .
471 .
473 .rs
474 .sp
475 By default, \fBpcretest\fP uses the standard PCRE matching function,
476 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
477 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
478 different way, and has some restrictions. The differences between the two
479 functions are described in the
480 .\" HREF
481 \fBpcrematching\fP
482 .\"
483 documentation.
484 .P
485 If a data line contains the \eD escape sequence, or if the command line
486 contains the \fB-dfa\fP option, the alternative matching function is called.
487 This function finds all possible matches at a given point. If, however, the \eF
488 escape sequence is present in the data line, it stops after the first match is
489 found. This is always the shortest possible match.
490 .
491 .
493 .rs
494 .sp
495 This section describes the output when the normal matching function,
496 \fBpcre_exec()\fP, is being used.
497 .P
498 When a match succeeds, pcretest outputs the list of captured substrings that
499 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
500 the whole pattern. Otherwise, it outputs "No match" when the return is
501 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
502 substring when \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL. For any other
503 returns, it outputs the PCRE negative error number. Here is an example of an
504 interactive \fBpcretest\fP run.
505 .sp
506 $ pcretest
507 PCRE version 7.0 30-Nov-2006
508 .sp
509 re> /^abc(\ed+)/
510 data> abc123
511 0: abc123
512 1: 123
513 data> xyz
514 No match
515 .sp
516 Note that unset capturing substrings that are not followed by one that is set
517 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
518 the following example, there are two capturing substrings, but when the first
519 data line is matched, the second, unset substring is not shown. An "internal"
520 unset substring is shown as "<unset>", as for the second data line.
521 .sp
522 re> /(a)|(b)/
523 data> a
524 0: a
525 1: a
526 data> b
527 0: b
528 1: <unset>
529 2: b
530 .sp
531 If the strings contain any non-printing characters, they are output as \e0x
532 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
533 pattern. See below for the definition of non-printing characters. If the
534 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
535 the the rest of the subject string, identified by "0+" like this:
536 .sp
537 re> /cat/+
538 data> cataract
539 0: cat
540 0+ aract
541 .sp
542 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
543 matching attempts are output in sequence, like this:
544 .sp
545 re> /\eBi(\ew\ew)/g
546 data> Mississippi
547 0: iss
548 1: ss
549 0: iss
550 1: ss
551 0: ipp
552 1: pp
553 .sp
554 "No match" is output only if the first match attempt fails.
555 .P
556 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
557 data line that is successfully matched, the substrings extracted by the
558 convenience functions are output with C, G, or L after the string number
559 instead of a colon. This is in addition to the normal full list. The string
560 length (that is, the return from the extraction function) is given in
561 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
562 .P
563 Note that whereas patterns can be continued over several lines (a plain ">"
564 prompt is used for continuations), data lines may not. However newlines can be
565 included in data by means of the \en escape (or \er, \er\en, etc., depending on
566 the newline sequence setting).
567 .
568 .
569 .
571 .rs
572 .sp
573 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
574 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
575 output consists of a list of all the matches that start at the first point in
576 the subject where there is at least one match. For example:
577 .sp
578 re> /(tang|tangerine|tan)/
579 data> yellow tangerine\eD
580 0: tangerine
581 1: tang
582 2: tan
583 .sp
584 (Using the normal matching function on this data finds only "tang".) The
585 longest matching string is always given first (and numbered zero). After a
586 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
587 partially matching substring.
588 .P
589 If \fB/g\fP is present on the pattern, the search for further matches resumes
590 at the end of the longest match. For example:
591 .sp
592 re> /(tang|tangerine|tan)/g
593 data> yellow tangerine and tangy sultana\eD
594 0: tangerine
595 1: tang
596 2: tan
597 0: tang
598 1: tan
599 0: tan
600 .sp
601 Since the matching function does not support substring capture, the escape
602 sequences that are concerned with captured substrings are not relevant.
603 .
604 .
606 .rs
607 .sp
608 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
609 indicating that the subject partially matched the pattern, you can restart the
610 match with additional subject data by means of the \eR escape sequence. For
611 example:
612 .sp
613 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
614 data> 23ja\eP\eD
615 Partial match: 23ja
616 data> n05\eR\eD
617 0: n05
618 .sp
619 For further information about partial matching, see the
620 .\" HREF
621 \fBpcrepartial\fP
622 .\"
623 documentation.
624 .
625 .
627 .rs
628 .sp
629 If the pattern contains any callout requests, \fBpcretest\fP's callout function
630 is called during matching. This works with both matching functions. By default,
631 the called function displays the callout number, the start and current
632 positions in the text at the callout time, and the next pattern item to be
633 tested. For example, the output
634 .sp
635 --->pqrabcdef
636 0 ^ ^ \ed
637 .sp
638 indicates that callout number 0 occurred for a match attempt starting at the
639 fourth character of the subject string, when the pointer was at the seventh
640 character of the data, and when the next pattern item was \ed. Just one
641 circumflex is output if the start and current positions are the same.
642 .P
643 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
644 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
645 callout number, the offset in the pattern, preceded by a plus, is output. For
646 example:
647 .sp
648 re> /\ed?[A-E]\e*/C
649 data> E*
650 --->E*
651 +0 ^ \ed?
652 +3 ^ [A-E]
653 +8 ^^ \e*
654 +10 ^ ^
655 0: E*
656 .sp
657 The callout function in \fBpcretest\fP returns zero (carry on matching) by
658 default, but you can use a \eC item in a data line (as described above) to
659 change this.
660 .P
661 Inserting callouts can be helpful when using \fBpcretest\fP to check
662 complicated regular expressions. For further information about callouts, see
663 the
664 .\" HREF
665 \fBpcrecallout\fP
666 .\"
667 documentation.
668 .
669 .
670 .
672 .rs
673 .sp
674 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
675 bytes other than 32-126 are always treated as non-printing characters are are
676 therefore shown as hex escapes.
677 .P
678 When \fBpcretest\fP is outputting text that is a matched part of a subject
679 string, it behaves in the same way, unless a different locale has been set for
680 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
681 function to distinguish printing and non-printing characters.
682 .
683 .
684 .
686 .rs
687 .sp
688 The facilities described in this section are not available when the POSIX
689 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
690 specified.
691 .P
692 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
693 compiled pattern to a file, by following the modifiers with > and a file name.
694 For example:
695 .sp
696 /pattern/im >/some/file
697 .sp
698 See the
699 .\" HREF
700 \fBpcreprecompile\fP
701 .\"
702 documentation for a discussion about saving and re-using compiled patterns.
703 .P
704 The data that is written is binary. The first eight bytes are the length of the
705 compiled pattern data followed by the length of the optional study data, each
706 written as four bytes in big-endian order (most significant byte first). If
707 there is no study data (either the pattern was not studied, or studying did not
708 return any data), the second length is zero. The lengths are followed by an
709 exact copy of the compiled pattern. If there is additional study data, this
710 follows immediately after the compiled pattern. After writing the file,
711 \fBpcretest\fP expects to read a new pattern.
712 .P
713 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
714 name instead of a pattern. The name of the file must not contain a < character,
715 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
716 characters.
717 For example:
718 .sp
719 re> </some/file
720 Compiled regex loaded from /some/file
721 No study data
722 .sp
723 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
724 the usual way.
725 .P
726 You can copy a file written by \fBpcretest\fP to a different host and reload it
727 there, even if the new host has opposite endianness to the one on which the
728 pattern was compiled. For example, you can compile on an i86 machine and run on
729 a SPARC machine.
730 .P
731 File names for saving and reloading can be absolute or relative, but note that
732 the shell facility of expanding a file name that starts with a tilde (~) is not
733 available.
734 .P
735 The ability to save and reload files in \fBpcretest\fP is intended for testing
736 and experimentation. It is not intended for production use because only a
737 single pattern can be written to a file. Furthermore, there is no facility for
738 supplying custom character tables for use with a reloaded pattern. If the
739 original pattern was compiled with custom tables, an attempt to match a subject
740 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
741 Finally, if you attempt to load a file that is not in the correct format, the
742 result is undefined.
743 .
744 .
745 .SH "SEE ALSO"
746 .rs
747 .sp
748 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
749 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
750 .
751 .
753 .rs
754 .sp
755 .nf
756 Philip Hazel
757 University Computing Service
758 Cambridge CB2 3QH, England.
759 .fi
760 .
761 .
763 .rs
764 .sp
765 .nf
766 Last updated: 14 June 2010
767 Copyright (c) 1997-2010 University of Cambridge.
768 .fi


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