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Revision 606 - (show annotations)
Mon Jun 6 17:46:22 2011 UTC (10 years, 1 month ago) by ph10
File size: 31796 byte(s)
Tidy the API for _pcre_valid_utf8() to a more suitable form for a future public 
release. Also make -s in pcretest force a study for every regex.
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 byte code) modifier; the
29 internal 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.
60 .TP 10
61 \fB-o\fP \fIosize\fP
62 Set the number of elements in the output vector that is used when calling
63 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
64 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
65 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
66 changed for individual matching calls by including \eO in the data line (see
67 below).
68 .TP 10
69 \fB-p\fP
70 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
71 used to call PCRE. None of the other options has any effect when \fB-p\fP is
72 set.
73 .TP 10
74 \fB-q\fP
75 Do not output the version number of \fBpcretest\fP at the start of execution.
76 .TP 10
77 \fB-S\fP \fIsize\fP
78 On Unix-like systems, set the size of the run-time stack to \fIsize\fP
79 megabytes.
80 .TP 10
81 \fB-s\fP
82 Behave as if each regex has the \fB/S\fP modifier; in other words, force each
83 regex to be studied.
84 .TP 10
85 \fB-t\fP
86 Run each compile, study, and match many times with a timer, and output
87 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
88 \fB-t\fP, because you will then get the size output a zillion times, and the
89 timing will be distorted. You can control the number of iterations that are
90 used for timing by following \fB-t\fP with a number (as a separate item on the
91 command line). For example, "-t 1000" would iterate 1000 times. The default is
92 to iterate 500000 times.
93 .TP 10
94 \fB-tm\fP
95 This is like \fB-t\fP except that it times only the matching phase, not the
96 compile or study phases.
97 .
98 .
100 .rs
101 .sp
102 If \fBpcretest\fP is given two filename arguments, it reads from the first and
103 writes to the second. If it is given only one filename argument, it reads from
104 that file and writes to stdout. Otherwise, it reads from stdin and writes to
105 stdout, and prompts for each line of input, using "re>" to prompt for regular
106 expressions, and "data>" to prompt for data lines.
107 .P
108 When \fBpcretest\fP is built, a configuration option can specify that it should
109 be linked with the \fBlibreadline\fP library. When this is done, if the input
110 is from a terminal, it is read using the \fBreadline()\fP function. This
111 provides line-editing and history facilities. The output from the \fB-help\fP
112 option states whether or not \fBreadline()\fP will be used.
113 .P
114 The program handles any number of sets of input on a single input file. Each
115 set starts with a regular expression, and continues with any number of data
116 lines to be matched against the pattern.
117 .P
118 Each data line is matched separately and independently. If you want to do
119 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
120 etc., depending on the newline setting) in a single line of input to encode the
121 newline sequences. There is no limit on the length of data lines; the input
122 buffer is automatically extended if it is too small.
123 .P
124 An empty line signals the end of the data lines, at which point a new regular
125 expression is read. The regular expressions are given enclosed in any
126 non-alphanumeric delimiters other than backslash, for example:
127 .sp
128 /(a|bc)x+yz/
129 .sp
130 White space before the initial delimiter is ignored. A regular expression may
131 be continued over several input lines, in which case the newline characters are
132 included within it. It is possible to include the delimiter within the pattern
133 by escaping it, for example
134 .sp
135 /abc\e/def/
136 .sp
137 If you do so, the escape and the delimiter form part of the pattern, but since
138 delimiters are always non-alphanumeric, this does not affect its interpretation.
139 If the terminating delimiter is immediately followed by a backslash, for
140 example,
141 .sp
142 /abc/\e
143 .sp
144 then a backslash is added to the end of the pattern. This is done to provide a
145 way of testing the error condition that arises if a pattern finishes with a
146 backslash, because
147 .sp
148 /abc\e/
149 .sp
150 is interpreted as the first line of a pattern that starts with "abc/", causing
151 pcretest to read the next line as a continuation of the regular expression.
152 .
153 .
155 .rs
156 .sp
157 A pattern may be followed by any number of modifiers, which are mostly single
158 characters. Following Perl usage, these are referred to below as, for example,
159 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
160 always be a slash, and no slash is used when writing modifiers. White space may
161 appear between the final pattern delimiter and the first modifier, and between
162 the modifiers themselves.
163 .P
164 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
165 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
166 \fBpcre_compile()\fP is called. These four modifier letters have the same
167 effect as they do in Perl. For example:
168 .sp
169 /caseless/i
170 .sp
171 The following table shows additional modifiers for setting PCRE compile-time
172 options that do not correspond to anything in Perl:
173 .sp
174 \fB/8\fP PCRE_UTF8
183 \fB/W\fP PCRE_UCP
187 \fB/<cr>\fP PCRE_NEWLINE_CR
188 \fB/<lf>\fP PCRE_NEWLINE_LF
189 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
190 \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
191 \fB/<any>\fP PCRE_NEWLINE_ANY
192 \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
193 \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
194 .sp
195 The modifiers that are enclosed in angle brackets are literal strings as shown,
196 including the angle brackets, but the letters can be in either case. This
197 example sets multiline matching with CRLF as the line ending sequence:
198 .sp
199 /^abc/m<crlf>
200 .sp
201 As well as turning on the PCRE_UTF8 option, the \fB/8\fP modifier also causes
202 any non-printing characters in output strings to be printed using the
203 \ex{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
204 options are given in the
205 .\" HREF
206 \fBpcreapi\fP
207 .\"
208 documentation.
209 .
210 .
211 .SS "Finding all matches in a string"
212 .rs
213 .sp
214 Searching for all possible matches within each subject string can be requested
215 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
216 again to search the remainder of the subject string. The difference between
217 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
218 \fBpcre_exec()\fP to start searching at a new point within the entire string
219 (which is in effect what Perl does), whereas the latter passes over a shortened
220 substring. This makes a difference to the matching process if the pattern
221 begins with a lookbehind assertion (including \eb or \eB).
222 .P
223 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
224 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
225 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
226 same point. If this second match fails, the start offset is advanced, and the
227 normal match is retried. This imitates the way Perl handles such cases when
228 using the \fB/g\fP modifier or the \fBsplit()\fP function. Normally, the start
229 offset is advanced by one character, but if the newline convention recognizes
230 CRLF as a newline, and the current character is CR followed by LF, an advance
231 of two is used.
232 .
233 .
234 .SS "Other modifiers"
235 .rs
236 .sp
237 There are yet more modifiers for controlling the way \fBpcretest\fP
238 operates.
239 .P
240 The \fB/+\fP modifier requests that as well as outputting the substring that
241 matched the entire pattern, pcretest should in addition output the remainder of
242 the subject string. This is useful for tests where the subject contains
243 multiple copies of the same substring.
244 .P
245 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
246 output a representation of the compiled byte code after compilation. Normally
247 this information contains length and offset values; however, if \fB/Z\fP is
248 also present, this data is replaced by spaces. This is a special feature for
249 use in the automatic test scripts; it ensures that the same output is generated
250 for different internal link sizes.
251 .P
252 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
253 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
254 .P
255 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
256 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
257 facility is for testing the feature in PCRE that allows it to execute patterns
258 that were compiled on a host with a different endianness. This feature is not
259 available when the POSIX interface to PCRE is being used, that is, when the
260 \fB/P\fP pattern modifier is specified. See also the section about saving and
261 reloading compiled patterns below.
262 .P
263 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
264 compiled pattern (whether it is anchored, has a fixed first character, and
265 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
266 pattern. If the pattern is studied, the results of that are also output.
267 .P
268 The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking
269 control verbs that are returned from calls to \fBpcre_exec()\fP. It causes
270 \fBpcretest\fP to create a \fBpcre_extra\fP block if one has not already been
271 created by a call to \fBpcre_study()\fP, and to set the PCRE_EXTRA_MARK flag
272 and the \fBmark\fP field within it, every time that \fBpcre_exec()\fP is
273 called. If the variable that the \fBmark\fP field points to is non-NULL for a
274 match, non-match, or partial match, \fBpcretest\fP prints the string to which
275 it points. For a match, this is shown on a line by itself, tagged with "MK:".
276 For a non-match it is added to the message.
277 .P
278 The \fB/L\fP modifier must be followed directly by the name of a locale, for
279 example,
280 .sp
281 /pattern/Lfr_FR
282 .sp
283 For this reason, it must be the last modifier. The given locale is set,
284 \fBpcre_maketables()\fP is called to build a set of character tables for the
285 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
286 regular expression. Without an \fB/L\fP (or \fB/T\fP) modifier, NULL is passed
287 as the tables pointer; that is, \fB/L\fP applies only to the expression on
288 which it appears.
289 .P
290 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
291 pattern to be output.
292 .P
293 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
294 expression has been compiled, and the results used when the expression is
295 matched.
296 .P
297 The \fB/T\fP modifier must be followed by a single digit. It causes a specific
298 set of built-in character tables to be passed to \fBpcre_compile()\fP. It is
299 used in the standard PCRE tests to check behaviour with different character
300 tables. The digit specifies the tables as follows:
301 .sp
302 0 the default ASCII tables, as distributed in
303 pcre_chartables.c.dist
304 1 a set of tables defining ISO 8859 characters
305 .sp
306 In table 1, some characters whose codes are greater than 128 are identified as
307 letters, digits, spaces, etc.
308 .
309 .
310 .SS "Using the POSIX wrapper API"
311 .rs
312 .sp
313 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
314 API rather than its native API. When \fB/P\fP is set, the following modifiers
315 set options for the \fBregcomp()\fP function:
316 .sp
317 /i REG_ICASE
320 /s REG_DOTALL )
321 /U REG_UNGREEDY ) These options are not part of
322 /W REG_UCP ) the POSIX standard
323 /8 REG_UTF8 )
324 .sp
325 The \fB/+\fP modifier works as described above. All other modifiers are
326 ignored.
327 .
328 .
330 .rs
331 .sp
332 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
333 white space is removed, and it is then scanned for \e escapes. Some of these
334 are pretty esoteric features, intended for checking out some of the more
335 complicated features of PCRE. If you are just testing "ordinary" regular
336 expressions, you probably don't need any of these. The following escapes are
337 recognized:
338 .sp
339 \ea alarm (BEL, \ex07)
340 \eb backspace (\ex08)
341 \ee escape (\ex27)
342 \ef form feed (\ex0c)
343 \en newline (\ex0a)
344 .\" JOIN
345 \eqdd set the PCRE_MATCH_LIMIT limit to dd
346 (any number of digits)
347 \er carriage return (\ex0d)
348 \et tab (\ex09)
349 \ev vertical tab (\ex0b)
350 \ennn octal character (up to 3 octal digits)
351 always a byte unless > 255 in UTF-8 mode
352 \exhh hexadecimal byte (up to 2 hex digits)
353 .\" JOIN
354 \ex{hh...} hexadecimal character, any number of digits
355 in UTF-8 mode
356 .\" JOIN
357 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
358 or \fBpcre_dfa_exec()\fP
359 .\" JOIN
360 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
361 or \fBpcre_dfa_exec()\fP
362 .\" JOIN
363 \eCdd call pcre_copy_substring() for substring dd
364 after a successful match (number less than 32)
365 .\" JOIN
366 \eCname call pcre_copy_named_substring() for substring
367 "name" after a successful match (name termin-
368 ated by next non alphanumeric character)
369 .\" JOIN
370 \eC+ show the current captured substrings at callout
371 time
372 \eC- do not supply a callout function
373 .\" JOIN
374 \eC!n return 1 instead of 0 when callout number n is
375 reached
376 .\" JOIN
377 \eC!n!m return 1 instead of 0 when callout number n is
378 reached for the nth time
379 .\" JOIN
380 \eC*n pass the number n (may be negative) as callout
381 data; this is used as the callout return value
382 \eD use the \fBpcre_dfa_exec()\fP match function
383 \eF only shortest match for \fBpcre_dfa_exec()\fP
384 .\" JOIN
385 \eGdd call pcre_get_substring() for substring dd
386 after a successful match (number less than 32)
387 .\" JOIN
388 \eGname call pcre_get_named_substring() for substring
389 "name" after a successful match (name termin-
390 ated by next non-alphanumeric character)
391 .\" JOIN
392 \eL call pcre_get_substringlist() after a
393 successful match
394 .\" JOIN
395 \eM discover the minimum MATCH_LIMIT and
397 .\" JOIN
398 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
399 or \fBpcre_dfa_exec()\fP; if used twice, pass the
401 .\" JOIN
402 \eOdd set the size of the output vector passed to
403 \fBpcre_exec()\fP to dd (any number of digits)
404 .\" JOIN
405 \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP
406 or \fBpcre_dfa_exec()\fP; if used twice, pass the
408 .\" JOIN
409 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
410 (any number of digits)
411 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
412 \eS output details of memory get/free calls during matching
413 .\" JOIN
414 \eY pass the PCRE_NO_START_OPTIMIZE option to \fBpcre_exec()\fP
415 or \fBpcre_dfa_exec()\fP
416 .\" JOIN
417 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
418 or \fBpcre_dfa_exec()\fP
419 .\" JOIN
420 \e? pass the PCRE_NO_UTF8_CHECK option to
421 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
422 .\" JOIN
423 \e>dd start the match at offset dd (optional "-"; then
424 any number of digits); this sets the \fIstartoffset\fP
425 argument for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
426 .\" JOIN
427 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
428 or \fBpcre_dfa_exec()\fP
429 .\" JOIN
430 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
431 or \fBpcre_dfa_exec()\fP
432 .\" JOIN
433 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
434 or \fBpcre_dfa_exec()\fP
435 .\" JOIN
436 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
437 or \fBpcre_dfa_exec()\fP
438 .\" JOIN
439 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
440 or \fBpcre_dfa_exec()\fP
441 .sp
442 Note that \exhh always specifies one byte, even in UTF-8 mode; this makes it
443 possible to construct invalid UTF-8 sequences for testing purposes. On the
444 other hand, \ex{hh} is interpreted as a UTF-8 character in UTF-8 mode,
445 generating more than one byte if the value is greater than 127. When not in
446 UTF-8 mode, it generates one byte for values less than 256, and causes an error
447 for greater values.
448 .P
449 The escapes that specify line ending sequences are literal strings, exactly as
450 shown. No more than one newline setting should be present in any data line.
451 .P
452 A backslash followed by anything else just escapes the anything else. If
453 the very last character is a backslash, it is ignored. This gives a way of
454 passing an empty line as data, since a real empty line terminates the data
455 input.
456 .P
457 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
458 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
459 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
460 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
461 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
462 place, and checking it out can be instructive. For most simple matches, the
463 number is quite small, but for patterns with very large numbers of matching
464 possibilities, it can become large very quickly with increasing length of
465 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
466 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
467 to complete the match attempt.
468 .P
469 When \eO is used, the value specified may be higher or lower than the size set
470 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
471 the call of \fBpcre_exec()\fP for the line in which it appears.
472 .P
473 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
474 API to be used, the only option-setting sequences that have any effect are \eB,
475 \eN, and \eZ, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
476 to be passed to \fBregexec()\fP.
477 .P
478 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
479 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
480 any number of hexadecimal digits inside the braces. The result is from one to
481 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
482 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
483 valid Unicode code points, or indeed valid UTF-8 characters according to the
484 later rules in RFC 3629.
485 .
486 .
488 .rs
489 .sp
490 By default, \fBpcretest\fP uses the standard PCRE matching function,
491 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
492 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
493 different way, and has some restrictions. The differences between the two
494 functions are described in the
495 .\" HREF
496 \fBpcrematching\fP
497 .\"
498 documentation.
499 .P
500 If a data line contains the \eD escape sequence, or if the command line
501 contains the \fB-dfa\fP option, the alternative matching function is called.
502 This function finds all possible matches at a given point. If, however, the \eF
503 escape sequence is present in the data line, it stops after the first match is
504 found. This is always the shortest possible match.
505 .
506 .
508 .rs
509 .sp
510 This section describes the output when the normal matching function,
511 \fBpcre_exec()\fP, is being used.
512 .P
513 When a match succeeds, \fBpcretest\fP outputs the list of captured substrings
514 that \fBpcre_exec()\fP returns, starting with number 0 for the string that
515 matched the whole pattern. Otherwise, it outputs "No match" when the return is
516 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
517 substring when \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL. (Note that this is
518 the entire substring that was inspected during the partial match; it may
519 include characters before the actual match start if a lookbehind assertion,
520 \eK, \eb, or \eB was involved.) For any other return, \fBpcretest\fP outputs
521 the PCRE negative error number and a short descriptive phrase. If the error is
522 a failed UTF-8 string check, the byte offset of the start of the failing
523 character and the reason code are also output, provided that the size of the
524 output vector is at least two. Here is an example of an interactive
525 \fBpcretest\fP run.
526 .sp
527 $ pcretest
528 PCRE version 8.13 2011-04-30
529 .sp
530 re> /^abc(\ed+)/
531 data> abc123
532 0: abc123
533 1: 123
534 data> xyz
535 No match
536 .sp
537 Unset capturing substrings that are not followed by one that is set are not
538 returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In the
539 following example, there are two capturing substrings, but when the first data
540 line is matched, the second, unset substring is not shown. An "internal" unset
541 substring is shown as "<unset>", as for the second data line.
542 .sp
543 re> /(a)|(b)/
544 data> a
545 0: a
546 1: a
547 data> b
548 0: b
549 1: <unset>
550 2: b
551 .sp
552 If the strings contain any non-printing characters, they are output as \e0x
553 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
554 pattern. See below for the definition of non-printing characters. If the
555 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
556 the the rest of the subject string, identified by "0+" like this:
557 .sp
558 re> /cat/+
559 data> cataract
560 0: cat
561 0+ aract
562 .sp
563 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
564 matching attempts are output in sequence, like this:
565 .sp
566 re> /\eBi(\ew\ew)/g
567 data> Mississippi
568 0: iss
569 1: ss
570 0: iss
571 1: ss
572 0: ipp
573 1: pp
574 .sp
575 "No match" is output only if the first match attempt fails. Here is an example
576 of a failure message (the offset 4 that is specified by \e>4 is past the end of
577 the subject string):
578 .sp
579 re> /xyz/
580 data> xyz\>4
581 Error -24 (bad offset value)
582 .P
583 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
584 data line that is successfully matched, the substrings extracted by the
585 convenience functions are output with C, G, or L after the string number
586 instead of a colon. This is in addition to the normal full list. The string
587 length (that is, the return from the extraction function) is given in
588 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
589 .P
590 Note that whereas patterns can be continued over several lines (a plain ">"
591 prompt is used for continuations), data lines may not. However newlines can be
592 included in data by means of the \en escape (or \er, \er\en, etc., depending on
593 the newline sequence setting).
594 .
595 .
596 .
598 .rs
599 .sp
600 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
601 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
602 output consists of a list of all the matches that start at the first point in
603 the subject where there is at least one match. For example:
604 .sp
605 re> /(tang|tangerine|tan)/
606 data> yellow tangerine\eD
607 0: tangerine
608 1: tang
609 2: tan
610 .sp
611 (Using the normal matching function on this data finds only "tang".) The
612 longest matching string is always given first (and numbered zero). After a
613 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
614 partially matching substring. (Note that this is the entire substring that was
615 inspected during the partial match; it may include characters before the actual
616 match start if a lookbehind assertion, \eK, \eb, or \eB was involved.)
617 .P
618 If \fB/g\fP is present on the pattern, the search for further matches resumes
619 at the end of the longest match. For example:
620 .sp
621 re> /(tang|tangerine|tan)/g
622 data> yellow tangerine and tangy sultana\eD
623 0: tangerine
624 1: tang
625 2: tan
626 0: tang
627 1: tan
628 0: tan
629 .sp
630 Since the matching function does not support substring capture, the escape
631 sequences that are concerned with captured substrings are not relevant.
632 .
633 .
635 .rs
636 .sp
637 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
638 indicating that the subject partially matched the pattern, you can restart the
639 match with additional subject data by means of the \eR escape sequence. For
640 example:
641 .sp
642 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
643 data> 23ja\eP\eD
644 Partial match: 23ja
645 data> n05\eR\eD
646 0: n05
647 .sp
648 For further information about partial matching, see the
649 .\" HREF
650 \fBpcrepartial\fP
651 .\"
652 documentation.
653 .
654 .
656 .rs
657 .sp
658 If the pattern contains any callout requests, \fBpcretest\fP's callout function
659 is called during matching. This works with both matching functions. By default,
660 the called function displays the callout number, the start and current
661 positions in the text at the callout time, and the next pattern item to be
662 tested. For example, the output
663 .sp
664 --->pqrabcdef
665 0 ^ ^ \ed
666 .sp
667 indicates that callout number 0 occurred for a match attempt starting at the
668 fourth character of the subject string, when the pointer was at the seventh
669 character of the data, and when the next pattern item was \ed. Just one
670 circumflex is output if the start and current positions are the same.
671 .P
672 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
673 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
674 callout number, the offset in the pattern, preceded by a plus, is output. For
675 example:
676 .sp
677 re> /\ed?[A-E]\e*/C
678 data> E*
679 --->E*
680 +0 ^ \ed?
681 +3 ^ [A-E]
682 +8 ^^ \e*
683 +10 ^ ^
684 0: E*
685 .sp
686 The callout function in \fBpcretest\fP returns zero (carry on matching) by
687 default, but you can use a \eC item in a data line (as described above) to
688 change this.
689 .P
690 Inserting callouts can be helpful when using \fBpcretest\fP to check
691 complicated regular expressions. For further information about callouts, see
692 the
693 .\" HREF
694 \fBpcrecallout\fP
695 .\"
696 documentation.
697 .
698 .
699 .
701 .rs
702 .sp
703 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
704 bytes other than 32-126 are always treated as non-printing characters are are
705 therefore shown as hex escapes.
706 .P
707 When \fBpcretest\fP is outputting text that is a matched part of a subject
708 string, it behaves in the same way, unless a different locale has been set for
709 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
710 function to distinguish printing and non-printing characters.
711 .
712 .
713 .
715 .rs
716 .sp
717 The facilities described in this section are not available when the POSIX
718 interface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
719 specified.
720 .P
721 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
722 compiled pattern to a file, by following the modifiers with > and a file name.
723 For example:
724 .sp
725 /pattern/im >/some/file
726 .sp
727 See the
728 .\" HREF
729 \fBpcreprecompile\fP
730 .\"
731 documentation for a discussion about saving and re-using compiled patterns.
732 .P
733 The data that is written is binary. The first eight bytes are the length of the
734 compiled pattern data followed by the length of the optional study data, each
735 written as four bytes in big-endian order (most significant byte first). If
736 there is no study data (either the pattern was not studied, or studying did not
737 return any data), the second length is zero. The lengths are followed by an
738 exact copy of the compiled pattern. If there is additional study data, this
739 follows immediately after the compiled pattern. After writing the file,
740 \fBpcretest\fP expects to read a new pattern.
741 .P
742 A saved pattern can be reloaded into \fBpcretest\fP by specifying < and a file
743 name instead of a pattern. The name of the file must not contain a < character,
744 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
745 characters.
746 For example:
747 .sp
748 re> </some/file
749 Compiled regex loaded from /some/file
750 No study data
751 .sp
752 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
753 the usual way.
754 .P
755 You can copy a file written by \fBpcretest\fP to a different host and reload it
756 there, even if the new host has opposite endianness to the one on which the
757 pattern was compiled. For example, you can compile on an i86 machine and run on
758 a SPARC machine.
759 .P
760 File names for saving and reloading can be absolute or relative, but note that
761 the shell facility of expanding a file name that starts with a tilde (~) is not
762 available.
763 .P
764 The ability to save and reload files in \fBpcretest\fP is intended for testing
765 and experimentation. It is not intended for production use because only a
766 single pattern can be written to a file. Furthermore, there is no facility for
767 supplying custom character tables for use with a reloaded pattern. If the
768 original pattern was compiled with custom tables, an attempt to match a subject
769 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
770 Finally, if you attempt to load a file that is not in the correct format, the
771 result is undefined.
772 .
773 .
774 .SH "SEE ALSO"
775 .rs
776 .sp
777 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
778 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
779 .
780 .
782 .rs
783 .sp
784 .nf
785 Philip Hazel
786 University Computing Service
787 Cambridge CB2 3QH, England.
788 .fi
789 .
790 .
792 .rs
793 .sp
794 .nf
795 Last updated: 06 June 2011
796 Copyright (c) 1997-2011 University of Cambridge.
797 .fi


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