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1 .TH PCRETEST 1
2 .SH NAME
3 pcretest - a program for testing Perl-compatible regular expressions.
4 .SH SYNOPSIS
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 .
24 .SH OPTIONS
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 Output the size of each compiled pattern after it has been compiled. This is
54 equivalent to adding \fB/M\fP to each regular expression. For compatibility
55 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
56 .TP 10
57 \fB-o\fP \fIosize\fP
58 Set the number of elements in the output vector that is used when calling
59 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
60 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
61 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
62 changed for individual matching calls by including \eO in the data line (see
63 below).
64 .TP 10
65 \fB-p\fP
66 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
67 used to call PCRE. None of the other options has any effect when \fB-p\fP is
68 set.
69 .TP 10
70 \fB-q\fP
71 Do not output the version number of \fBpcretest\fP at the start of execution.
72 .TP 10
73 \fB-S\fP \fIsize\fP
74 On Unix-like systems, set the size of the runtime stack to \fIsize\fP
75 megabytes.
76 .TP 10
77 \fB-t\fP
78 Run each compile, study, and match many times with a timer, and output
79 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
80 \fB-t\fP, because you will then get the size output a zillion times, and the
81 timing will be distorted. You can control the number of iterations that are
82 used for timing by following \fB-t\fP with a number (as a separate item on the
83 command line). For example, "-t 1000" would iterate 1000 times. The default is
84 to iterate 500000 times.
85 .TP 10
86 \fB-tm\fP
87 This is like \fB-t\fP except that it times only the matching phase, not the
88 compile or study phases.
89 .
90 .
91 .SH DESCRIPTION
92 .rs
93 .sp
94 If \fBpcretest\fP is given two filename arguments, it reads from the first and
95 writes to the second. If it is given only one filename argument, it reads from
96 that file and writes to stdout. Otherwise, it reads from stdin and writes to
97 stdout, and prompts for each line of input, using "re>" to prompt for regular
98 expressions, and "data>" to prompt for data lines.
99 .P
100 When \fBpcretest\fP is built, a configuration option can specify that it should
101 be linked with the \fBlibreadline\fP library. When this is done, if the input
102 is from a terminal, it is read using the \fBreadline()\fP function. This
103 provides line-editing and history facilities. The output from the \fB-help\fP
104 option states whether or not \fBreadline()\fP will be used.
105 .P
106 The program handles any number of sets of input on a single input file. Each
107 set starts with a regular expression, and continues with any number of data
108 lines to be matched against the pattern.
109 .P
110 Each data line is matched separately and independently. If you want to do
111 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
112 etc., depending on the newline setting) in a single line of input to encode the
113 newline sequences. There is no limit on the length of data lines; the input
114 buffer is automatically extended if it is too small.
115 .P
116 An empty line signals the end of the data lines, at which point a new regular
117 expression is read. The regular expressions are given enclosed in any
118 non-alphanumeric delimiters other than backslash, for example:
119 .sp
120 /(a|bc)x+yz/
121 .sp
122 White space before the initial delimiter is ignored. A regular expression may
123 be continued over several input lines, in which case the newline characters are
124 included within it. It is possible to include the delimiter within the pattern
125 by escaping it, for example
126 .sp
127 /abc\e/def/
128 .sp
129 If you do so, the escape and the delimiter form part of the pattern, but since
130 delimiters are always non-alphanumeric, this does not affect its interpretation.
131 If the terminating delimiter is immediately followed by a backslash, for
132 example,
133 .sp
134 /abc/\e
135 .sp
136 then a backslash is added to the end of the pattern. This is done to provide a
137 way of testing the error condition that arises if a pattern finishes with a
138 backslash, because
139 .sp
140 /abc\e/
141 .sp
142 is interpreted as the first line of a pattern that starts with "abc/", causing
143 pcretest to read the next line as a continuation of the regular expression.
144 .
145 .
146 .SH "PATTERN MODIFIERS"
147 .rs
148 .sp
149 A pattern may be followed by any number of modifiers, which are mostly single
150 characters. Following Perl usage, these are referred to below as, for example,
151 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
152 always be a slash, and no slash is used when writing modifiers. Whitespace may
153 appear between the final pattern delimiter and the first modifier, and between
154 the modifiers themselves.
155 .P
156 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
157 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
158 \fBpcre_compile()\fP is called. These four modifier letters have the same
159 effect as they do in Perl. For example:
160 .sp
161 /caseless/i
162 .sp
163 The following table shows additional modifiers for setting PCRE options that do
164 not correspond to anything in Perl:
165 .sp
166 \fB/A\fP PCRE_ANCHORED
167 \fB/C\fP PCRE_AUTO_CALLOUT
168 \fB/E\fP PCRE_DOLLAR_ENDONLY
169 \fB/f\fP PCRE_FIRSTLINE
170 \fB/J\fP PCRE_DUPNAMES
171 \fB/N\fP PCRE_NO_AUTO_CAPTURE
172 \fB/U\fP PCRE_UNGREEDY
173 \fB/X\fP PCRE_EXTRA
174 \fB/<cr>\fP PCRE_NEWLINE_CR
175 \fB/<lf>\fP PCRE_NEWLINE_LF
176 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
177 \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
178 \fB/<any>\fP PCRE_NEWLINE_ANY
179 \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
180 \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
181 .sp
182 Those specifying line ending sequences are literal strings as shown, but the
183 letters can be in either case. This example sets multiline matching with CRLF
184 as the line ending sequence:
185 .sp
186 /^abc/m<crlf>
187 .sp
188 Details of the meanings of these PCRE options are given in the
189 .\" HREF
190 \fBpcreapi\fP
191 .\"
192 documentation.
193 .
194 .
195 .SS "Finding all matches in a string"
196 .rs
197 .sp
198 Searching for all possible matches within each subject string can be requested
199 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
200 again to search the remainder of the subject string. The difference between
201 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
202 \fBpcre_exec()\fP to start searching at a new point within the entire string
203 (which is in effect what Perl does), whereas the latter passes over a shortened
204 substring. This makes a difference to the matching process if the pattern
205 begins with a lookbehind assertion (including \eb or \eB).
206 .P
207 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
208 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
209 flags set in order to search for another, non-empty, match at the same point.
210 If this second match fails, the start offset is advanced by one, and the normal
211 match is retried. This imitates the way Perl handles such cases when using the
212 \fB/g\fP modifier or the \fBsplit()\fP function.
213 .
214 .
215 .SS "Other modifiers"
216 .rs
217 .sp
218 There are yet more modifiers for controlling the way \fBpcretest\fP
219 operates.
220 .P
221 The \fB/+\fP modifier requests that as well as outputting the substring that
222 matched the entire pattern, pcretest should in addition output the remainder of
223 the subject string. This is useful for tests where the subject contains
224 multiple copies of the same substring.
225 .P
226 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
227 output a representation of the compiled byte code after compilation. Normally
228 this information contains length and offset values; however, if \fB/Z\fP is
229 also present, this data is replaced by spaces. This is a special feature for
230 use in the automatic test scripts; it ensures that the same output is generated
231 for different internal link sizes.
232 .P
233 The \fB/L\fP modifier must be followed directly by the name of a locale, for
234 example,
235 .sp
236 /pattern/Lfr_FR
237 .sp
238 For this reason, it must be the last modifier. The given locale is set,
239 \fBpcre_maketables()\fP is called to build a set of character tables for the
240 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
241 regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
242 pointer; that is, \fB/L\fP applies only to the expression on which it appears.
243 .P
244 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
245 compiled pattern (whether it is anchored, has a fixed first character, and
246 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
247 pattern. If the pattern is studied, the results of that are also output.
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/S\fP modifier causes \fBpcre_study()\fP to be called after the
261 expression has been compiled, and the results used when the expression is
262 matched.
263 .P
264 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
265 pattern to be output.
266 .P
267 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
268 API rather than its native API. When this is done, all other modifiers except
269 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
270 present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
271 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
272 .P
273 The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
274 option set. This turns on support for UTF-8 character handling in PCRE,
275 provided that it was compiled with this support enabled. This modifier also
276 causes any non-printing characters in output strings to be printed using the
277 \ex{hh...} notation if they are valid UTF-8 sequences.
278 .P
279 If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
280 call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
281 checking of the string for UTF-8 validity.
282 .
283 .
284 .SH "DATA LINES"
285 .rs
286 .sp
287 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
288 whitespace is removed, and it is then scanned for \e escapes. Some of these are
289 pretty esoteric features, intended for checking out some of the more
290 complicated features of PCRE. If you are just testing "ordinary" regular
291 expressions, you probably don't need any of these. The following escapes are
292 recognized:
293 .sp
294 \ea alarm (BEL, \ex07)
295 \eb backspace (\ex08)
296 \ee escape (\ex27)
297 \ef formfeed (\ex0c)
298 \en newline (\ex0a)
299 .\" JOIN
300 \eqdd set the PCRE_MATCH_LIMIT limit to dd
301 (any number of digits)
302 \er carriage return (\ex0d)
303 \et tab (\ex09)
304 \ev vertical tab (\ex0b)
305 \ennn octal character (up to 3 octal digits)
306 \exhh hexadecimal character (up to 2 hex digits)
307 .\" JOIN
308 \ex{hh...} hexadecimal character, any number of digits
309 in UTF-8 mode
310 .\" JOIN
311 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
312 or \fBpcre_dfa_exec()\fP
313 .\" JOIN
314 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
315 or \fBpcre_dfa_exec()\fP
316 .\" JOIN
317 \eCdd call pcre_copy_substring() for substring dd
318 after a successful match (number less than 32)
319 .\" JOIN
320 \eCname call pcre_copy_named_substring() for substring
321 "name" after a successful match (name termin-
322 ated by next non alphanumeric character)
323 .\" JOIN
324 \eC+ show the current captured substrings at callout
325 time
326 \eC- do not supply a callout function
327 .\" JOIN
328 \eC!n return 1 instead of 0 when callout number n is
329 reached
330 .\" JOIN
331 \eC!n!m return 1 instead of 0 when callout number n is
332 reached for the nth time
333 .\" JOIN
334 \eC*n pass the number n (may be negative) as callout
335 data; this is used as the callout return value
336 \eD use the \fBpcre_dfa_exec()\fP match function
337 \eF only shortest match for \fBpcre_dfa_exec()\fP
338 .\" JOIN
339 \eGdd call pcre_get_substring() for substring dd
340 after a successful match (number less than 32)
341 .\" JOIN
342 \eGname call pcre_get_named_substring() for substring
343 "name" after a successful match (name termin-
344 ated by next non-alphanumeric character)
345 .\" JOIN
346 \eL call pcre_get_substringlist() after a
347 successful match
348 .\" JOIN
349 \eM discover the minimum MATCH_LIMIT and
350 MATCH_LIMIT_RECURSION settings
351 .\" JOIN
352 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
353 or \fBpcre_dfa_exec()\fP
354 .\" JOIN
355 \eOdd set the size of the output vector passed to
356 \fBpcre_exec()\fP to dd (any number of digits)
357 .\" JOIN
358 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
359 or \fBpcre_dfa_exec()\fP
360 .\" JOIN
361 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
362 (any number of digits)
363 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
364 \eS output details of memory get/free calls during matching
365 .\" JOIN
366 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
367 or \fBpcre_dfa_exec()\fP
368 .\" JOIN
369 \e? pass the PCRE_NO_UTF8_CHECK option to
370 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
371 \e>dd start the match at offset dd (any number of digits);
372 .\" JOIN
373 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
374 or \fBpcre_dfa_exec()\fP
375 .\" JOIN
376 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
377 or \fBpcre_dfa_exec()\fP
378 .\" JOIN
379 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
380 or \fBpcre_dfa_exec()\fP
381 .\" JOIN
382 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
383 or \fBpcre_dfa_exec()\fP
384 .\" JOIN
385 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
386 or \fBpcre_dfa_exec()\fP
387 .\" JOIN
388 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
389 or \fBpcre_dfa_exec()\fP
390 .sp
391 The escapes that specify line ending sequences are literal strings, exactly as
392 shown. No more than one newline setting should be present in any data line.
393 .P
394 A backslash followed by anything else just escapes the anything else. If
395 the very last character is a backslash, it is ignored. This gives a way of
396 passing an empty line as data, since a real empty line terminates the data
397 input.
398 .P
399 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
400 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
401 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
402 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
403 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
404 place, and checking it out can be instructive. For most simple matches, the
405 number is quite small, but for patterns with very large numbers of matching
406 possibilities, it can become large very quickly with increasing length of
407 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
408 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
409 to complete the match attempt.
410 .P
411 When \eO is used, the value specified may be higher or lower than the size set
412 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
413 the call of \fBpcre_exec()\fP for the line in which it appears.
414 .P
415 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
416 API to be used, the only option-setting sequences that have any effect are \eB
417 and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
418 \fBregexec()\fP.
419 .P
420 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
421 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
422 any number of hexadecimal digits inside the braces. The result is from one to
423 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
424 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
425 valid Unicode code points, or indeed valid UTF-8 characters according to the
426 later rules in RFC 3629.
427 .
428 .
429 .SH "THE ALTERNATIVE MATCHING FUNCTION"
430 .rs
431 .sp
432 By default, \fBpcretest\fP uses the standard PCRE matching function,
433 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
434 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
435 different way, and has some restrictions. The differences between the two
436 functions are described in the
437 .\" HREF
438 \fBpcrematching\fP
439 .\"
440 documentation.
441 .P
442 If a data line contains the \eD escape sequence, or if the command line
443 contains the \fB-dfa\fP option, the alternative matching function is called.
444 This function finds all possible matches at a given point. If, however, the \eF
445 escape sequence is present in the data line, it stops after the first match is
446 found. This is always the shortest possible match.
447 .
448 .
449 .SH "DEFAULT OUTPUT FROM PCRETEST"
450 .rs
451 .sp
452 This section describes the output when the normal matching function,
453 \fBpcre_exec()\fP, is being used.
454 .P
455 When a match succeeds, pcretest outputs the list of captured substrings that
456 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
457 the whole pattern. Otherwise, it outputs "No match" or "Partial match"
458 when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
459 respectively, and otherwise the PCRE negative error number. Here is an example
460 of an interactive \fBpcretest\fP run.
461 .sp
462 $ pcretest
463 PCRE version 7.0 30-Nov-2006
464 .sp
465 re> /^abc(\ed+)/
466 data> abc123
467 0: abc123
468 1: 123
469 data> xyz
470 No match
471 .sp
472 Note that unset capturing substrings that are not followed by one that is set
473 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
474 the following example, there are two capturing substrings, but when the first
475 data line is matched, the second, unset substring is not shown. An "internal"
476 unset substring is shown as "<unset>", as for the second data line.
477 .sp
478 re> /(a)|(b)/
479 data> a
480 0: a
481 1: a
482 data> b
483 0: b
484 1: <unset>
485 2: b
486 .sp
487 If the strings contain any non-printing characters, they are output as \e0x
488 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
489 pattern. See below for the definition of non-printing characters. If the
490 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
491 the the rest of the subject string, identified by "0+" like this:
492 .sp
493 re> /cat/+
494 data> cataract
495 0: cat
496 0+ aract
497 .sp
498 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
499 matching attempts are output in sequence, like this:
500 .sp
501 re> /\eBi(\ew\ew)/g
502 data> Mississippi
503 0: iss
504 1: ss
505 0: iss
506 1: ss
507 0: ipp
508 1: pp
509 .sp
510 "No match" is output only if the first match attempt fails.
511 .P
512 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
513 data line that is successfully matched, the substrings extracted by the
514 convenience functions are output with C, G, or L after the string number
515 instead of a colon. This is in addition to the normal full list. The string
516 length (that is, the return from the extraction function) is given in
517 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
518 .P
519 Note that whereas patterns can be continued over several lines (a plain ">"
520 prompt is used for continuations), data lines may not. However newlines can be
521 included in data by means of the \en escape (or \er, \er\en, etc., depending on
522 the newline sequence setting).
523 .
524 .
525 .
526 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
527 .rs
528 .sp
529 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
530 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
531 output consists of a list of all the matches that start at the first point in
532 the subject where there is at least one match. For example:
533 .sp
534 re> /(tang|tangerine|tan)/
535 data> yellow tangerine\eD
536 0: tangerine
537 1: tang
538 2: tan
539 .sp
540 (Using the normal matching function on this data finds only "tang".) The
541 longest matching string is always given first (and numbered zero).
542 .P
543 If \fB/g\fP is present on the pattern, the search for further matches resumes
544 at the end of the longest match. For example:
545 .sp
546 re> /(tang|tangerine|tan)/g
547 data> yellow tangerine and tangy sultana\eD
548 0: tangerine
549 1: tang
550 2: tan
551 0: tang
552 1: tan
553 0: tan
554 .sp
555 Since the matching function does not support substring capture, the escape
556 sequences that are concerned with captured substrings are not relevant.
557 .
558 .
559 .SH "RESTARTING AFTER A PARTIAL MATCH"
560 .rs
561 .sp
562 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
563 indicating that the subject partially matched the pattern, you can restart the
564 match with additional subject data by means of the \eR escape sequence. For
565 example:
566 .sp
567 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
568 data> 23ja\eP\eD
569 Partial match: 23ja
570 data> n05\eR\eD
571 0: n05
572 .sp
573 For further information about partial matching, see the
574 .\" HREF
575 \fBpcrepartial\fP
576 .\"
577 documentation.
578 .
579 .
580 .SH CALLOUTS
581 .rs
582 .sp
583 If the pattern contains any callout requests, \fBpcretest\fP's callout function
584 is called during matching. This works with both matching functions. By default,
585 the called function displays the callout number, the start and current
586 positions in the text at the callout time, and the next pattern item to be
587 tested. For example, the output
588 .sp
589 --->pqrabcdef
590 0 ^ ^ \ed
591 .sp
592 indicates that callout number 0 occurred for a match attempt starting at the
593 fourth character of the subject string, when the pointer was at the seventh
594 character of the data, and when the next pattern item was \ed. Just one
595 circumflex is output if the start and current positions are the same.
596 .P
597 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
598 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
599 callout number, the offset in the pattern, preceded by a plus, is output. For
600 example:
601 .sp
602 re> /\ed?[A-E]\e*/C
603 data> E*
604 --->E*
605 +0 ^ \ed?
606 +3 ^ [A-E]
607 +8 ^^ \e*
608 +10 ^ ^
609 0: E*
610 .sp
611 The callout function in \fBpcretest\fP returns zero (carry on matching) by
612 default, but you can use a \eC item in a data line (as described above) to
613 change this.
614 .P
615 Inserting callouts can be helpful when using \fBpcretest\fP to check
616 complicated regular expressions. For further information about callouts, see
617 the
618 .\" HREF
619 \fBpcrecallout\fP
620 .\"
621 documentation.
622 .
623 .
624 .
625 .SH "NON-PRINTING CHARACTERS"
626 .rs
627 .sp
628 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
629 bytes other than 32-126 are always treated as non-printing characters are are
630 therefore shown as hex escapes.
631 .P
632 When \fBpcretest\fP is outputting text that is a matched part of a subject
633 string, it behaves in the same way, unless a different locale has been set for
634 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
635 function to distinguish printing and non-printing characters.
636 .
637 .
638 .
639 .SH "SAVING AND RELOADING COMPILED PATTERNS"
640 .rs
641 .sp
642 The facilities described in this section are not available when the POSIX
643 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
644 specified.
645 .P
646 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
647 compiled pattern to a file, by following the modifiers with > and a file name.
648 For example:
649 .sp
650 /pattern/im >/some/file
651 .sp
652 See the
653 .\" HREF
654 \fBpcreprecompile\fP
655 .\"
656 documentation for a discussion about saving and re-using compiled patterns.
657 .P
658 The data that is written is binary. The first eight bytes are the length of the
659 compiled pattern data followed by the length of the optional study data, each
660 written as four bytes in big-endian order (most significant byte first). If
661 there is no study data (either the pattern was not studied, or studying did not
662 return any data), the second length is zero. The lengths are followed by an
663 exact copy of the compiled pattern. If there is additional study data, this
664 follows immediately after the compiled pattern. After writing the file,
665 \fBpcretest\fP expects to read a new pattern.
666 .P
667 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
668 name instead of a pattern. The name of the file must not contain a < character,
669 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
670 characters.
671 For example:
672 .sp
673 re> </some/file
674 Compiled regex loaded from /some/file
675 No study data
676 .sp
677 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
678 the usual way.
679 .P
680 You can copy a file written by \fBpcretest\fP to a different host and reload it
681 there, even if the new host has opposite endianness to the one on which the
682 pattern was compiled. For example, you can compile on an i86 machine and run on
683 a SPARC machine.
684 .P
685 File names for saving and reloading can be absolute or relative, but note that
686 the shell facility of expanding a file name that starts with a tilde (~) is not
687 available.
688 .P
689 The ability to save and reload files in \fBpcretest\fP is intended for testing
690 and experimentation. It is not intended for production use because only a
691 single pattern can be written to a file. Furthermore, there is no facility for
692 supplying custom character tables for use with a reloaded pattern. If the
693 original pattern was compiled with custom tables, an attempt to match a subject
694 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
695 Finally, if you attempt to load a file that is not in the correct format, the
696 result is undefined.
697 .
698 .
699 .SH "SEE ALSO"
700 .rs
701 .sp
702 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
703 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
704 .
705 .
706 .SH AUTHOR
707 .rs
708 .sp
709 .nf
710 Philip Hazel
711 University Computing Service
712 Cambridge CB2 3QH, England.
713 .fi
714 .
715 .
716 .SH REVISION
717 .rs
718 .sp
719 .nf
720 Last updated: 18 December 2007
721 Copyright (c) 1997-2007 University of Cambridge.
722 .fi

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