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Revision 616 - (show annotations)
Mon Jul 11 15:55:25 2011 UTC (9 years, 7 months ago) by ph10
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Add the ++ feature to pcretest.
3 pcretest - a program for testing Perl-compatible regular expressions.
5 .rs
6 .sp
7 .B pcretest "[options] [input file [output file]]"
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. The input for \fBpcretest\fP is a sequence of regular expression
22 patterns and strings to be matched, as described below. The output shows the
23 result of each match. Options on the command line and the patterns control PCRE
24 options and exactly what is output.
25 .
26 .
28 .rs
29 .TP 10
30 \fB-b\fP
31 Behave as if each pattern has the \fB/B\fP (show byte code) modifier; the
32 internal form is output after compilation.
33 .TP 10
34 \fB-C\fP
35 Output the version number of the PCRE library, and all available information
36 about the optional features that are included, and then exit.
37 .TP 10
38 \fB-d\fP
39 Behave as if each pattern has the \fB/D\fP (debug) modifier; the internal
40 form and information about the compiled pattern is output after compilation;
41 \fB-d\fP is equivalent to \fB-b -i\fP.
42 .TP 10
43 \fB-dfa\fP
44 Behave as if each data line contains the \eD escape sequence; this causes the
45 alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the
46 standard \fBpcre_exec()\fP function (more detail is given below).
47 .TP 10
48 \fB-help\fP
49 Output a brief summary these options and then exit.
50 .TP 10
51 \fB-i\fP
52 Behave as if each pattern has the \fB/I\fP modifier; information about the
53 compiled pattern is given after compilation.
54 .TP 10
55 \fB-M\fP
56 Behave as if each data line contains the \eM escape sequence; this causes
57 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
58 calling \fBpcre_exec()\fP repeatedly with different limits.
59 .TP 10
60 \fB-m\fP
61 Output the size of each compiled pattern after it has been compiled. This is
62 equivalent to adding \fB/M\fP to each regular expression.
63 .TP 10
64 \fB-o\fP \fIosize\fP
65 Set the number of elements in the output vector that is used when calling
66 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
67 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
68 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
69 changed for individual matching calls by including \eO in the data line (see
70 below).
71 .TP 10
72 \fB-p\fP
73 Behave as if each pattern has the \fB/P\fP modifier; the POSIX wrapper API is
74 used to call PCRE. None of the other options has any effect when \fB-p\fP is
75 set.
76 .TP 10
77 \fB-q\fP
78 Do not output the version number of \fBpcretest\fP at the start of execution.
79 .TP 10
80 \fB-S\fP \fIsize\fP
81 On Unix-like systems, set the size of the run-time stack to \fIsize\fP
82 megabytes.
83 .TP 10
84 \fB-s\fP
85 Behave as if each pattern has the \fB/S\fP modifier; in other words, force each
86 pattern to be studied. If the \fB/I\fP or \fB/D\fP option is present on a
87 pattern (requesting output about the compiled pattern), information about the
88 result of studying is not included when studying is caused only by \fB-s\fP and
89 neither \fB-i\fP nor \fB-d\fP is present on the command line. This behaviour
90 means that the output from tests that are run with and without \fB-s\fP should
91 be identical, except when options that output information about the actual
92 running of a match are set. The \fB-M\fP, \fB-t\fP, and \fB-tm\fP options,
93 which give information about resources used, are likely to produce different
94 output with and without \fB-s\fP. Output may also differ if the \fB/C\fP option
95 is present on an individual pattern. This uses callouts to trace the the
96 matching process, and this may be different between studied and non-studied
97 patterns. If the pattern contains (*MARK) items there may also be differences,
98 for the same reason. The \fB-s\fP command line option can be overridden for
99 specific patterns that should never be studied (see the /S option below).
100 .TP 10
101 \fB-t\fP
102 Run each compile, study, and match many times with a timer, and output
103 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
104 \fB-t\fP, because you will then get the size output a zillion times, and the
105 timing will be distorted. You can control the number of iterations that are
106 used for timing by following \fB-t\fP with a number (as a separate item on the
107 command line). For example, "-t 1000" would iterate 1000 times. The default is
108 to iterate 500000 times.
109 .TP 10
110 \fB-tm\fP
111 This is like \fB-t\fP except that it times only the matching phase, not the
112 compile or study phases.
113 .
114 .
116 .rs
117 .sp
118 If \fBpcretest\fP is given two filename arguments, it reads from the first and
119 writes to the second. If it is given only one filename argument, it reads from
120 that file and writes to stdout. Otherwise, it reads from stdin and writes to
121 stdout, and prompts for each line of input, using "re>" to prompt for regular
122 expressions, and "data>" to prompt for data lines.
123 .P
124 When \fBpcretest\fP is built, a configuration option can specify that it should
125 be linked with the \fBlibreadline\fP library. When this is done, if the input
126 is from a terminal, it is read using the \fBreadline()\fP function. This
127 provides line-editing and history facilities. The output from the \fB-help\fP
128 option states whether or not \fBreadline()\fP will be used.
129 .P
130 The program handles any number of sets of input on a single input file. Each
131 set starts with a regular expression, and continues with any number of data
132 lines to be matched against the pattern.
133 .P
134 Each data line is matched separately and independently. If you want to do
135 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
136 etc., depending on the newline setting) in a single line of input to encode the
137 newline sequences. There is no limit on the length of data lines; the input
138 buffer is automatically extended if it is too small.
139 .P
140 An empty line signals the end of the data lines, at which point a new regular
141 expression is read. The regular expressions are given enclosed in any
142 non-alphanumeric delimiters other than backslash, for example:
143 .sp
144 /(a|bc)x+yz/
145 .sp
146 White space before the initial delimiter is ignored. A regular expression may
147 be continued over several input lines, in which case the newline characters are
148 included within it. It is possible to include the delimiter within the pattern
149 by escaping it, for example
150 .sp
151 /abc\e/def/
152 .sp
153 If you do so, the escape and the delimiter form part of the pattern, but since
154 delimiters are always non-alphanumeric, this does not affect its interpretation.
155 If the terminating delimiter is immediately followed by a backslash, for
156 example,
157 .sp
158 /abc/\e
159 .sp
160 then a backslash is added to the end of the pattern. This is done to provide a
161 way of testing the error condition that arises if a pattern finishes with a
162 backslash, because
163 .sp
164 /abc\e/
165 .sp
166 is interpreted as the first line of a pattern that starts with "abc/", causing
167 pcretest to read the next line as a continuation of the regular expression.
168 .
169 .
171 .rs
172 .sp
173 A pattern may be followed by any number of modifiers, which are mostly single
174 characters. Following Perl usage, these are referred to below as, for example,
175 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
176 always be a slash, and no slash is used when writing modifiers. White space may
177 appear between the final pattern delimiter and the first modifier, and between
178 the modifiers themselves.
179 .P
180 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
181 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
182 \fBpcre_compile()\fP is called. These four modifier letters have the same
183 effect as they do in Perl. For example:
184 .sp
185 /caseless/i
186 .sp
187 The following table shows additional modifiers for setting PCRE compile-time
188 options that do not correspond to anything in Perl:
189 .sp
190 \fB/8\fP PCRE_UTF8
199 \fB/W\fP PCRE_UCP
203 \fB/<cr>\fP PCRE_NEWLINE_CR
204 \fB/<lf>\fP PCRE_NEWLINE_LF
205 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
206 \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
207 \fB/<any>\fP PCRE_NEWLINE_ANY
208 \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
209 \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
210 .sp
211 The modifiers that are enclosed in angle brackets are literal strings as shown,
212 including the angle brackets, but the letters within can be in either case.
213 This example sets multiline matching with CRLF as the line ending sequence:
214 .sp
215 /^abc/m<CRLF>
216 .sp
217 As well as turning on the PCRE_UTF8 option, the \fB/8\fP modifier also causes
218 any non-printing characters in output strings to be printed using the
219 \ex{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
220 options are given in the
221 .\" HREF
222 \fBpcreapi\fP
223 .\"
224 documentation.
225 .
226 .
227 .SS "Finding all matches in a string"
228 .rs
229 .sp
230 Searching for all possible matches within each subject string can be requested
231 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
232 again to search the remainder of the subject string. The difference between
233 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
234 \fBpcre_exec()\fP to start searching at a new point within the entire string
235 (which is in effect what Perl does), whereas the latter passes over a shortened
236 substring. This makes a difference to the matching process if the pattern
237 begins with a lookbehind assertion (including \eb or \eB).
238 .P
239 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
240 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
241 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
242 same point. If this second match fails, the start offset is advanced, and the
243 normal match is retried. This imitates the way Perl handles such cases when
244 using the \fB/g\fP modifier or the \fBsplit()\fP function. Normally, the start
245 offset is advanced by one character, but if the newline convention recognizes
246 CRLF as a newline, and the current character is CR followed by LF, an advance
247 of two is used.
248 .
249 .
250 .SS "Other modifiers"
251 .rs
252 .sp
253 There are yet more modifiers for controlling the way \fBpcretest\fP
254 operates.
255 .P
256 The \fB/+\fP modifier requests that as well as outputting the substring that
257 matched the entire pattern, \fBpcretest\fP should in addition output the
258 remainder of the subject string. This is useful for tests where the subject
259 contains multiple copies of the same substring. If the \fB+\fP modifier appears
260 twice, the same action is taken for captured substrings. In each case the
261 remainder is output on the following line with a plus character following the
262 capture number.
263 .P
264 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
265 output a representation of the compiled byte code after compilation. Normally
266 this information contains length and offset values; however, if \fB/Z\fP is
267 also present, this data is replaced by spaces. This is a special feature for
268 use in the automatic test scripts; it ensures that the same output is generated
269 for different internal link sizes.
270 .P
271 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
272 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
273 .P
274 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
275 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
276 facility is for testing the feature in PCRE that allows it to execute patterns
277 that were compiled on a host with a different endianness. This feature is not
278 available when the POSIX interface to PCRE is being used, that is, when the
279 \fB/P\fP pattern modifier is specified. See also the section about saving and
280 reloading compiled patterns below.
281 .P
282 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
283 compiled pattern (whether it is anchored, has a fixed first character, and
284 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
285 pattern. If the pattern is studied, the results of that are also output.
286 .P
287 The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking
288 control verbs that are returned from calls to \fBpcre_exec()\fP. It causes
289 \fBpcretest\fP to create a \fBpcre_extra\fP block if one has not already been
290 created by a call to \fBpcre_study()\fP, and to set the PCRE_EXTRA_MARK flag
291 and the \fBmark\fP field within it, every time that \fBpcre_exec()\fP is
292 called. If the variable that the \fBmark\fP field points to is non-NULL for a
293 match, non-match, or partial match, \fBpcretest\fP prints the string to which
294 it points. For a match, this is shown on a line by itself, tagged with "MK:".
295 For a non-match it is added to the message.
296 .P
297 The \fB/L\fP modifier must be followed directly by the name of a locale, for
298 example,
299 .sp
300 /pattern/Lfr_FR
301 .sp
302 For this reason, it must be the last modifier. The given locale is set,
303 \fBpcre_maketables()\fP is called to build a set of character tables for the
304 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
305 regular expression. Without an \fB/L\fP (or \fB/T\fP) modifier, NULL is passed
306 as the tables pointer; that is, \fB/L\fP applies only to the expression on
307 which it appears.
308 .P
309 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
310 pattern to be output.
311 .P
312 If the \fB/S\fP modifier appears once, it causes \fBpcre_study()\fP to be
313 called after the expression has been compiled, and the results used when the
314 expression is matched. If \fB/S\fP appears twice, it suppresses studying, even
315 if it was requested externally by the \fB-s\fP command line option. This makes
316 it possible to specify that certain patterns are always studied, and others are
317 never studied, independently of \fB-s\fP. This feature is used in the test
318 files in a few cases where the output is different when the pattern is studied.
319 .P
320 The \fB/T\fP modifier must be followed by a single digit. It causes a specific
321 set of built-in character tables to be passed to \fBpcre_compile()\fP. It is
322 used in the standard PCRE tests to check behaviour with different character
323 tables. The digit specifies the tables as follows:
324 .sp
325 0 the default ASCII tables, as distributed in
326 pcre_chartables.c.dist
327 1 a set of tables defining ISO 8859 characters
328 .sp
329 In table 1, some characters whose codes are greater than 128 are identified as
330 letters, digits, spaces, etc.
331 .
332 .
333 .SS "Using the POSIX wrapper API"
334 .rs
335 .sp
336 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
337 API rather than its native API. When \fB/P\fP is set, the following modifiers
338 set options for the \fBregcomp()\fP function:
339 .sp
340 /i REG_ICASE
343 /s REG_DOTALL )
344 /U REG_UNGREEDY ) These options are not part of
345 /W REG_UCP ) the POSIX standard
346 /8 REG_UTF8 )
347 .sp
348 The \fB/+\fP modifier works as described above. All other modifiers are
349 ignored.
350 .
351 .
353 .rs
354 .sp
355 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
356 white space is removed, and it is then scanned for \e escapes. Some of these
357 are pretty esoteric features, intended for checking out some of the more
358 complicated features of PCRE. If you are just testing "ordinary" regular
359 expressions, you probably don't need any of these. The following escapes are
360 recognized:
361 .sp
362 \ea alarm (BEL, \ex07)
363 \eb backspace (\ex08)
364 \ee escape (\ex27)
365 \ef form feed (\ex0c)
366 \en newline (\ex0a)
367 .\" JOIN
368 \eqdd set the PCRE_MATCH_LIMIT limit to dd
369 (any number of digits)
370 \er carriage return (\ex0d)
371 \et tab (\ex09)
372 \ev vertical tab (\ex0b)
373 \ennn octal character (up to 3 octal digits)
374 always a byte unless > 255 in UTF-8 mode
375 \exhh hexadecimal byte (up to 2 hex digits)
376 .\" JOIN
377 \ex{hh...} hexadecimal character, any number of digits
378 in UTF-8 mode
379 .\" JOIN
380 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
381 or \fBpcre_dfa_exec()\fP
382 .\" JOIN
383 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
384 or \fBpcre_dfa_exec()\fP
385 .\" JOIN
386 \eCdd call pcre_copy_substring() for substring dd
387 after a successful match (number less than 32)
388 .\" JOIN
389 \eCname call pcre_copy_named_substring() for substring
390 "name" after a successful match (name termin-
391 ated by next non alphanumeric character)
392 .\" JOIN
393 \eC+ show the current captured substrings at callout
394 time
395 \eC- do not supply a callout function
396 .\" JOIN
397 \eC!n return 1 instead of 0 when callout number n is
398 reached
399 .\" JOIN
400 \eC!n!m return 1 instead of 0 when callout number n is
401 reached for the nth time
402 .\" JOIN
403 \eC*n pass the number n (may be negative) as callout
404 data; this is used as the callout return value
405 \eD use the \fBpcre_dfa_exec()\fP match function
406 \eF only shortest match for \fBpcre_dfa_exec()\fP
407 .\" JOIN
408 \eGdd call pcre_get_substring() for substring dd
409 after a successful match (number less than 32)
410 .\" JOIN
411 \eGname call pcre_get_named_substring() for substring
412 "name" after a successful match (name termin-
413 ated by next non-alphanumeric character)
414 .\" JOIN
415 \eL call pcre_get_substringlist() after a
416 successful match
417 .\" JOIN
418 \eM discover the minimum MATCH_LIMIT and
420 .\" JOIN
421 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
422 or \fBpcre_dfa_exec()\fP; if used twice, pass the
424 .\" JOIN
425 \eOdd set the size of the output vector passed to
426 \fBpcre_exec()\fP to dd (any number of digits)
427 .\" JOIN
428 \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP
429 or \fBpcre_dfa_exec()\fP; if used twice, pass the
431 .\" JOIN
432 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
433 (any number of digits)
434 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
435 \eS output details of memory get/free calls during matching
436 .\" JOIN
437 \eY pass the PCRE_NO_START_OPTIMIZE option to \fBpcre_exec()\fP
438 or \fBpcre_dfa_exec()\fP
439 .\" JOIN
440 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
441 or \fBpcre_dfa_exec()\fP
442 .\" JOIN
443 \e? pass the PCRE_NO_UTF8_CHECK option to
444 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
445 .\" JOIN
446 \e>dd start the match at offset dd (optional "-"; then
447 any number of digits); this sets the \fIstartoffset\fP
448 argument for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
449 .\" JOIN
450 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
451 or \fBpcre_dfa_exec()\fP
452 .\" JOIN
453 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
454 or \fBpcre_dfa_exec()\fP
455 .\" JOIN
456 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
457 or \fBpcre_dfa_exec()\fP
458 .\" JOIN
459 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
460 or \fBpcre_dfa_exec()\fP
461 .\" JOIN
462 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
463 or \fBpcre_dfa_exec()\fP
464 .sp
465 Note that \exhh always specifies one byte, even in UTF-8 mode; this makes it
466 possible to construct invalid UTF-8 sequences for testing purposes. On the
467 other hand, \ex{hh} is interpreted as a UTF-8 character in UTF-8 mode,
468 generating more than one byte if the value is greater than 127. When not in
469 UTF-8 mode, it generates one byte for values less than 256, and causes an error
470 for greater values.
471 .P
472 The escapes that specify line ending sequences are literal strings, exactly as
473 shown. No more than one newline setting should be present in any data line.
474 .P
475 A backslash followed by anything else just escapes the anything else. If
476 the very last character is a backslash, it is ignored. This gives a way of
477 passing an empty line as data, since a real empty line terminates the data
478 input.
479 .P
480 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
481 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
482 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
483 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
484 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
485 place, and checking it out can be instructive. For most simple matches, the
486 number is quite small, but for patterns with very large numbers of matching
487 possibilities, it can become large very quickly with increasing length of
488 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
489 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
490 to complete the match attempt.
491 .P
492 When \eO is used, the value specified may be higher or lower than the size set
493 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
494 the call of \fBpcre_exec()\fP for the line in which it appears.
495 .P
496 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
497 API to be used, the only option-setting sequences that have any effect are \eB,
498 \eN, and \eZ, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
499 to be passed to \fBregexec()\fP.
500 .P
501 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
502 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
503 any number of hexadecimal digits inside the braces. The result is from one to
504 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
505 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
506 valid Unicode code points, or indeed valid UTF-8 characters according to the
507 later rules in RFC 3629.
508 .
509 .
511 .rs
512 .sp
513 By default, \fBpcretest\fP uses the standard PCRE matching function,
514 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
515 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
516 different way, and has some restrictions. The differences between the two
517 functions are described in the
518 .\" HREF
519 \fBpcrematching\fP
520 .\"
521 documentation.
522 .P
523 If a data line contains the \eD escape sequence, or if the command line
524 contains the \fB-dfa\fP option, the alternative matching function is called.
525 This function finds all possible matches at a given point. If, however, the \eF
526 escape sequence is present in the data line, it stops after the first match is
527 found. This is always the shortest possible match.
528 .
529 .
531 .rs
532 .sp
533 This section describes the output when the normal matching function,
534 \fBpcre_exec()\fP, is being used.
535 .P
536 When a match succeeds, \fBpcretest\fP outputs the list of captured substrings
537 that \fBpcre_exec()\fP returns, starting with number 0 for the string that
538 matched the whole pattern. Otherwise, it outputs "No match" when the return is
539 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
540 substring when \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL. (Note that this is
541 the entire substring that was inspected during the partial match; it may
542 include characters before the actual match start if a lookbehind assertion,
543 \eK, \eb, or \eB was involved.) For any other return, \fBpcretest\fP outputs
544 the PCRE negative error number and a short descriptive phrase. If the error is
545 a failed UTF-8 string check, the byte offset of the start of the failing
546 character and the reason code are also output, provided that the size of the
547 output vector is at least two. Here is an example of an interactive
548 \fBpcretest\fP run.
549 .sp
550 $ pcretest
551 PCRE version 8.13 2011-04-30
552 .sp
553 re> /^abc(\ed+)/
554 data> abc123
555 0: abc123
556 1: 123
557 data> xyz
558 No match
559 .sp
560 Unset capturing substrings that are not followed by one that is set are not
561 returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In the
562 following example, there are two capturing substrings, but when the first data
563 line is matched, the second, unset substring is not shown. An "internal" unset
564 substring is shown as "<unset>", as for the second data line.
565 .sp
566 re> /(a)|(b)/
567 data> a
568 0: a
569 1: a
570 data> b
571 0: b
572 1: <unset>
573 2: b
574 .sp
575 If the strings contain any non-printing characters, they are output as \e0x
576 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
577 pattern. See below for the definition of non-printing characters. If the
578 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
579 the the rest of the subject string, identified by "0+" like this:
580 .sp
581 re> /cat/+
582 data> cataract
583 0: cat
584 0+ aract
585 .sp
586 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
587 matching attempts are output in sequence, like this:
588 .sp
589 re> /\eBi(\ew\ew)/g
590 data> Mississippi
591 0: iss
592 1: ss
593 0: iss
594 1: ss
595 0: ipp
596 1: pp
597 .sp
598 "No match" is output only if the first match attempt fails. Here is an example
599 of a failure message (the offset 4 that is specified by \e>4 is past the end of
600 the subject string):
601 .sp
602 re> /xyz/
603 data> xyz\>4
604 Error -24 (bad offset value)
605 .P
606 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
607 data line that is successfully matched, the substrings extracted by the
608 convenience functions are output with C, G, or L after the string number
609 instead of a colon. This is in addition to the normal full list. The string
610 length (that is, the return from the extraction function) is given in
611 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
612 .P
613 Note that whereas patterns can be continued over several lines (a plain ">"
614 prompt is used for continuations), data lines may not. However newlines can be
615 included in data by means of the \en escape (or \er, \er\en, etc., depending on
616 the newline sequence setting).
617 .
618 .
619 .
621 .rs
622 .sp
623 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
624 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
625 output consists of a list of all the matches that start at the first point in
626 the subject where there is at least one match. For example:
627 .sp
628 re> /(tang|tangerine|tan)/
629 data> yellow tangerine\eD
630 0: tangerine
631 1: tang
632 2: tan
633 .sp
634 (Using the normal matching function on this data finds only "tang".) The
635 longest matching string is always given first (and numbered zero). After a
636 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
637 partially matching substring. (Note that this is the entire substring that was
638 inspected during the partial match; it may include characters before the actual
639 match start if a lookbehind assertion, \eK, \eb, or \eB was involved.)
640 .P
641 If \fB/g\fP is present on the pattern, the search for further matches resumes
642 at the end of the longest match. For example:
643 .sp
644 re> /(tang|tangerine|tan)/g
645 data> yellow tangerine and tangy sultana\eD
646 0: tangerine
647 1: tang
648 2: tan
649 0: tang
650 1: tan
651 0: tan
652 .sp
653 Since the matching function does not support substring capture, the escape
654 sequences that are concerned with captured substrings are not relevant.
655 .
656 .
658 .rs
659 .sp
660 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
661 indicating that the subject partially matched the pattern, you can restart the
662 match with additional subject data by means of the \eR escape sequence. For
663 example:
664 .sp
665 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
666 data> 23ja\eP\eD
667 Partial match: 23ja
668 data> n05\eR\eD
669 0: n05
670 .sp
671 For further information about partial matching, see the
672 .\" HREF
673 \fBpcrepartial\fP
674 .\"
675 documentation.
676 .
677 .
679 .rs
680 .sp
681 If the pattern contains any callout requests, \fBpcretest\fP's callout function
682 is called during matching. This works with both matching functions. By default,
683 the called function displays the callout number, the start and current
684 positions in the text at the callout time, and the next pattern item to be
685 tested. For example, the output
686 .sp
687 --->pqrabcdef
688 0 ^ ^ \ed
689 .sp
690 indicates that callout number 0 occurred for a match attempt starting at the
691 fourth character of the subject string, when the pointer was at the seventh
692 character of the data, and when the next pattern item was \ed. Just one
693 circumflex is output if the start and current positions are the same.
694 .P
695 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
696 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
697 callout number, the offset in the pattern, preceded by a plus, is output. For
698 example:
699 .sp
700 re> /\ed?[A-E]\e*/C
701 data> E*
702 --->E*
703 +0 ^ \ed?
704 +3 ^ [A-E]
705 +8 ^^ \e*
706 +10 ^ ^
707 0: E*
708 .sp
709 The callout function in \fBpcretest\fP returns zero (carry on matching) by
710 default, but you can use a \eC item in a data line (as described above) to
711 change this.
712 .P
713 Inserting callouts can be helpful when using \fBpcretest\fP to check
714 complicated regular expressions. For further information about callouts, see
715 the
716 .\" HREF
717 \fBpcrecallout\fP
718 .\"
719 documentation.
720 .
721 .
722 .
724 .rs
725 .sp
726 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
727 bytes other than 32-126 are always treated as non-printing characters are are
728 therefore shown as hex escapes.
729 .P
730 When \fBpcretest\fP is outputting text that is a matched part of a subject
731 string, it behaves in the same way, unless a different locale has been set for
732 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
733 function to distinguish printing and non-printing characters.
734 .
735 .
736 .
738 .rs
739 .sp
740 The facilities described in this section are not available when the POSIX
741 interface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
742 specified.
743 .P
744 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
745 compiled pattern to a file, by following the modifiers with > and a file name.
746 For example:
747 .sp
748 /pattern/im >/some/file
749 .sp
750 See the
751 .\" HREF
752 \fBpcreprecompile\fP
753 .\"
754 documentation for a discussion about saving and re-using compiled patterns.
755 .P
756 The data that is written is binary. The first eight bytes are the length of the
757 compiled pattern data followed by the length of the optional study data, each
758 written as four bytes in big-endian order (most significant byte first). If
759 there is no study data (either the pattern was not studied, or studying did not
760 return any data), the second length is zero. The lengths are followed by an
761 exact copy of the compiled pattern. If there is additional study data, this
762 follows immediately after the compiled pattern. After writing the file,
763 \fBpcretest\fP expects to read a new pattern.
764 .P
765 A saved pattern can be reloaded into \fBpcretest\fP by specifying < and a file
766 name instead of a pattern. The name of the file must not contain a < character,
767 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
768 characters.
769 For example:
770 .sp
771 re> </some/file
772 Compiled pattern loaded from /some/file
773 No study data
774 .sp
775 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
776 the usual way.
777 .P
778 You can copy a file written by \fBpcretest\fP to a different host and reload it
779 there, even if the new host has opposite endianness to the one on which the
780 pattern was compiled. For example, you can compile on an i86 machine and run on
781 a SPARC machine.
782 .P
783 File names for saving and reloading can be absolute or relative, but note that
784 the shell facility of expanding a file name that starts with a tilde (~) is not
785 available.
786 .P
787 The ability to save and reload files in \fBpcretest\fP is intended for testing
788 and experimentation. It is not intended for production use because only a
789 single pattern can be written to a file. Furthermore, there is no facility for
790 supplying custom character tables for use with a reloaded pattern. If the
791 original pattern was compiled with custom tables, an attempt to match a subject
792 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
793 Finally, if you attempt to load a file that is not in the correct format, the
794 result is undefined.
795 .
796 .
797 .SH "SEE ALSO"
798 .rs
799 .sp
800 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
801 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
802 .
803 .
805 .rs
806 .sp
807 .nf
808 Philip Hazel
809 University Computing Service
810 Cambridge CB2 3QH, England.
811 .fi
812 .
813 .
815 .rs
816 .sp
817 .nf
818 Last updated: 11 July 2011
819 Copyright (c) 1997-2011 University of Cambridge.
820 .fi


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