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Revision 691 - (show annotations)
Sun Sep 11 14:31:21 2011 UTC (9 years, 5 months ago) by ph10
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Final source and document tidies for 8.20-RC1.
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 or \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 \fB-s+\fP is used, the PCRE_STUDY_JIT_COMPILE flag is
87 passed to \fBpcre_study()\fP, causing just-in-time optimization to be set up if
88 it is available. If the \fB/I\fP or \fB/D\fP option is present on a pattern
89 (requesting output about the compiled pattern), information about the result of
90 studying is not included when studying is caused only by \fB-s\fP and neither
91 \fB-i\fP nor \fB-d\fP is present on the command line. This behaviour means that
92 the output from tests that are run with and without \fB-s\fP should be
93 identical, except when options that output information about the actual running
94 of a match are set. The \fB-M\fP, \fB-t\fP, and \fB-tm\fP options, which give
95 information about resources used, are likely to produce different output with
96 and without \fB-s\fP. Output may also differ if the \fB/C\fP option is present
97 on an individual pattern. This uses callouts to trace the the matching process,
98 and this may be different between studied and non-studied patterns. If the
99 pattern contains (*MARK) items there may also be differences, for the same
100 reason. The \fB-s\fP command line option can be overridden for specific
101 patterns that should never be studied (see the \fB/S\fP pattern modifier
102 below).
103 .TP 10
104 \fB-t\fP
105 Run each compile, study, and match many times with a timer, and output
106 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
107 \fB-t\fP, because you will then get the size output a zillion times, and the
108 timing will be distorted. You can control the number of iterations that are
109 used for timing by following \fB-t\fP with a number (as a separate item on the
110 command line). For example, "-t 1000" would iterate 1000 times. The default is
111 to iterate 500000 times.
112 .TP 10
113 \fB-tm\fP
114 This is like \fB-t\fP except that it times only the matching phase, not the
115 compile or study phases.
116 .
117 .
119 .rs
120 .sp
121 If \fBpcretest\fP is given two filename arguments, it reads from the first and
122 writes to the second. If it is given only one filename argument, it reads from
123 that file and writes to stdout. Otherwise, it reads from stdin and writes to
124 stdout, and prompts for each line of input, using "re>" to prompt for regular
125 expressions, and "data>" to prompt for data lines.
126 .P
127 When \fBpcretest\fP is built, a configuration option can specify that it should
128 be linked with the \fBlibreadline\fP library. When this is done, if the input
129 is from a terminal, it is read using the \fBreadline()\fP function. This
130 provides line-editing and history facilities. The output from the \fB-help\fP
131 option states whether or not \fBreadline()\fP will be used.
132 .P
133 The program handles any number of sets of input on a single input file. Each
134 set starts with a regular expression, and continues with any number of data
135 lines to be matched against the pattern.
136 .P
137 Each data line is matched separately and independently. If you want to do
138 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
139 etc., depending on the newline setting) in a single line of input to encode the
140 newline sequences. There is no limit on the length of data lines; the input
141 buffer is automatically extended if it is too small.
142 .P
143 An empty line signals the end of the data lines, at which point a new regular
144 expression is read. The regular expressions are given enclosed in any
145 non-alphanumeric delimiters other than backslash, for example:
146 .sp
147 /(a|bc)x+yz/
148 .sp
149 White space before the initial delimiter is ignored. A regular expression may
150 be continued over several input lines, in which case the newline characters are
151 included within it. It is possible to include the delimiter within the pattern
152 by escaping it, for example
153 .sp
154 /abc\e/def/
155 .sp
156 If you do so, the escape and the delimiter form part of the pattern, but since
157 delimiters are always non-alphanumeric, this does not affect its interpretation.
158 If the terminating delimiter is immediately followed by a backslash, for
159 example,
160 .sp
161 /abc/\e
162 .sp
163 then a backslash is added to the end of the pattern. This is done to provide a
164 way of testing the error condition that arises if a pattern finishes with a
165 backslash, because
166 .sp
167 /abc\e/
168 .sp
169 is interpreted as the first line of a pattern that starts with "abc/", causing
170 pcretest to read the next line as a continuation of the regular expression.
171 .
172 .
174 .rs
175 .sp
176 A pattern may be followed by any number of modifiers, which are mostly single
177 characters. Following Perl usage, these are referred to below as, for example,
178 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
179 always be a slash, and no slash is used when writing modifiers. White space may
180 appear between the final pattern delimiter and the first modifier, and between
181 the modifiers themselves.
182 .P
183 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
184 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
185 \fBpcre_compile()\fP is called. These four modifier letters have the same
186 effect as they do in Perl. For example:
187 .sp
188 /caseless/i
189 .sp
190 The following table shows additional modifiers for setting PCRE compile-time
191 options that do not correspond to anything in Perl:
192 .sp
193 \fB/8\fP PCRE_UTF8
202 \fB/W\fP PCRE_UCP
206 \fB/<cr>\fP PCRE_NEWLINE_CR
207 \fB/<lf>\fP PCRE_NEWLINE_LF
208 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
209 \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
210 \fB/<any>\fP PCRE_NEWLINE_ANY
211 \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
212 \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
213 .sp
214 The modifiers that are enclosed in angle brackets are literal strings as shown,
215 including the angle brackets, but the letters within can be in either case.
216 This example sets multiline matching with CRLF as the line ending sequence:
217 .sp
218 /^abc/m<CRLF>
219 .sp
220 As well as turning on the PCRE_UTF8 option, the \fB/8\fP modifier also causes
221 any non-printing characters in output strings to be printed using the
222 \ex{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
223 options are given in the
224 .\" HREF
225 \fBpcreapi\fP
226 .\"
227 documentation.
228 .
229 .
230 .SS "Finding all matches in a string"
231 .rs
232 .sp
233 Searching for all possible matches within each subject string can be requested
234 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
235 again to search the remainder of the subject string. The difference between
236 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
237 \fBpcre_exec()\fP to start searching at a new point within the entire string
238 (which is in effect what Perl does), whereas the latter passes over a shortened
239 substring. This makes a difference to the matching process if the pattern
240 begins with a lookbehind assertion (including \eb or \eB).
241 .P
242 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
243 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
244 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
245 same point. If this second match fails, the start offset is advanced, and the
246 normal match is retried. This imitates the way Perl handles such cases when
247 using the \fB/g\fP modifier or the \fBsplit()\fP function. Normally, the start
248 offset is advanced by one character, but if the newline convention recognizes
249 CRLF as a newline, and the current character is CR followed by LF, an advance
250 of two is used.
251 .
252 .
253 .SS "Other modifiers"
254 .rs
255 .sp
256 There are yet more modifiers for controlling the way \fBpcretest\fP
257 operates.
258 .P
259 The \fB/+\fP modifier requests that as well as outputting the substring that
260 matched the entire pattern, \fBpcretest\fP should in addition output the
261 remainder of the subject string. This is useful for tests where the subject
262 contains multiple copies of the same substring. If the \fB+\fP modifier appears
263 twice, the same action is taken for captured substrings. In each case the
264 remainder is output on the following line with a plus character following the
265 capture number. Note that this modifier must not immediately follow the /S
266 modifier because /S+ has another meaning.
267 .P
268 The \fB/=\fP modifier requests that the values of all potential captured
269 parentheses be output after a match by \fBpcre_exec()\fP. By default, only
270 those up to the highest one actually used in the match are output
271 (corresponding to the return code from \fBpcre_exec()\fP). Values in the
272 offsets vector corresponding to higher numbers should be set to -1, and these
273 are output as "<unset>". This modifier gives a way of checking that this is
274 happening.
275 .P
276 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
277 output a representation of the compiled byte code after compilation. Normally
278 this information contains length and offset values; however, if \fB/Z\fP is
279 also present, this data is replaced by spaces. This is a special feature for
280 use in the automatic test scripts; it ensures that the same output is generated
281 for different internal link sizes.
282 .P
283 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
284 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
285 .P
286 The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
287 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
288 facility is for testing the feature in PCRE that allows it to execute patterns
289 that were compiled on a host with a different endianness. This feature is not
290 available when the POSIX interface to PCRE is being used, that is, when the
291 \fB/P\fP pattern modifier is specified. See also the section about saving and
292 reloading compiled patterns below.
293 .P
294 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
295 compiled pattern (whether it is anchored, has a fixed first character, and
296 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
297 pattern. If the pattern is studied, the results of that are also output.
298 .P
299 The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking
300 control verbs that are returned from calls to \fBpcre_exec()\fP. It causes
301 \fBpcretest\fP to create a \fBpcre_extra\fP block if one has not already been
302 created by a call to \fBpcre_study()\fP, and to set the PCRE_EXTRA_MARK flag
303 and the \fBmark\fP field within it, every time that \fBpcre_exec()\fP is
304 called. If the variable that the \fBmark\fP field points to is non-NULL for a
305 match, non-match, or partial match, \fBpcretest\fP prints the string to which
306 it points. For a match, this is shown on a line by itself, tagged with "MK:".
307 For a non-match it is added to the message.
308 .P
309 The \fB/L\fP modifier must be followed directly by the name of a locale, for
310 example,
311 .sp
312 /pattern/Lfr_FR
313 .sp
314 For this reason, it must be the last modifier. The given locale is set,
315 \fBpcre_maketables()\fP is called to build a set of character tables for the
316 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
317 regular expression. Without an \fB/L\fP (or \fB/T\fP) modifier, NULL is passed
318 as the tables pointer; that is, \fB/L\fP applies only to the expression on
319 which it appears.
320 .P
321 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
322 pattern to be output.
323 .P
324 If the \fB/S\fP modifier appears once, it causes \fBpcre_study()\fP to be
325 called after the expression has been compiled, and the results used when the
326 expression is matched. If \fB/S\fP appears twice, it suppresses studying, even
327 if it was requested externally by the \fB-s\fP command line option. This makes
328 it possible to specify that certain patterns are always studied, and others are
329 never studied, independently of \fB-s\fP. This feature is used in the test
330 files in a few cases where the output is different when the pattern is studied.
331 .P
332 If the \fB/S\fP modifier is immediately followed by a + character, the call to
333 \fBpcre_study()\fP is made with the PCRE_STUDY_JIT_COMPILE option, requesting
334 just-in-time optimization support if it is available. Note that there is also a
335 \fB/+\fP modifier; it must not be given immediately after \fB/S\fP because this
336 will be misinterpreted. If JIT studying is successful, it will automatically be
337 used when \fBpcre_exec()\fP is run, except when incompatible run-time options
338 are specified. These include the partial matching options; a complete list is
339 given in the
340 .\" HREF
341 \fBpcrejit\fP
342 .\"
343 documentation. See also the \fB\eJ\fP escape sequence below for a way of
344 setting the size of the JIT stack.
345 .P
346 The \fB/T\fP modifier must be followed by a single digit. It causes a specific
347 set of built-in character tables to be passed to \fBpcre_compile()\fP. It is
348 used in the standard PCRE tests to check behaviour with different character
349 tables. The digit specifies the tables as follows:
350 .sp
351 0 the default ASCII tables, as distributed in
352 pcre_chartables.c.dist
353 1 a set of tables defining ISO 8859 characters
354 .sp
355 In table 1, some characters whose codes are greater than 128 are identified as
356 letters, digits, spaces, etc.
357 .
358 .
359 .SS "Using the POSIX wrapper API"
360 .rs
361 .sp
362 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
363 API rather than its native API. When \fB/P\fP is set, the following modifiers
364 set options for the \fBregcomp()\fP function:
365 .sp
366 /i REG_ICASE
369 /s REG_DOTALL )
370 /U REG_UNGREEDY ) These options are not part of
371 /W REG_UCP ) the POSIX standard
372 /8 REG_UTF8 )
373 .sp
374 The \fB/+\fP modifier works as described above. All other modifiers are
375 ignored.
376 .
377 .
379 .rs
380 .sp
381 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
382 white space is removed, and it is then scanned for \e escapes. Some of these
383 are pretty esoteric features, intended for checking out some of the more
384 complicated features of PCRE. If you are just testing "ordinary" regular
385 expressions, you probably don't need any of these. The following escapes are
386 recognized:
387 .sp
388 \ea alarm (BEL, \ex07)
389 \eb backspace (\ex08)
390 \ee escape (\ex27)
391 \ef form feed (\ex0c)
392 \en newline (\ex0a)
393 .\" JOIN
394 \eqdd set the PCRE_MATCH_LIMIT limit to dd
395 (any number of digits)
396 \er carriage return (\ex0d)
397 \et tab (\ex09)
398 \ev vertical tab (\ex0b)
399 \ennn octal character (up to 3 octal digits)
400 always a byte unless > 255 in UTF-8 mode
401 \exhh hexadecimal byte (up to 2 hex digits)
402 .\" JOIN
403 \ex{hh...} hexadecimal character, any number of digits
404 in UTF-8 mode
405 .\" JOIN
406 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
407 or \fBpcre_dfa_exec()\fP
408 .\" JOIN
409 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
410 or \fBpcre_dfa_exec()\fP
411 .\" JOIN
412 \eCdd call pcre_copy_substring() for substring dd
413 after a successful match (number less than 32)
414 .\" JOIN
415 \eCname call pcre_copy_named_substring() for substring
416 "name" after a successful match (name termin-
417 ated by next non alphanumeric character)
418 .\" JOIN
419 \eC+ show the current captured substrings at callout
420 time
421 \eC- do not supply a callout function
422 .\" JOIN
423 \eC!n return 1 instead of 0 when callout number n is
424 reached
425 .\" JOIN
426 \eC!n!m return 1 instead of 0 when callout number n is
427 reached for the nth time
428 .\" JOIN
429 \eC*n pass the number n (may be negative) as callout
430 data; this is used as the callout return value
431 \eD use the \fBpcre_dfa_exec()\fP match function
432 \eF only shortest match for \fBpcre_dfa_exec()\fP
433 .\" JOIN
434 \eGdd call pcre_get_substring() for substring dd
435 after a successful match (number less than 32)
436 .\" JOIN
437 \eGname call pcre_get_named_substring() for substring
438 "name" after a successful match (name termin-
439 ated by next non-alphanumeric character)
440 .\" JOIN
441 \eJdd set up a JIT stack of dd kilobytes maximum (any
442 number of digits)
443 .\" JOIN
444 \eL call pcre_get_substringlist() after a
445 successful match
446 .\" JOIN
447 \eM discover the minimum MATCH_LIMIT and
449 .\" JOIN
450 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
451 or \fBpcre_dfa_exec()\fP; if used twice, pass the
453 .\" JOIN
454 \eOdd set the size of the output vector passed to
455 \fBpcre_exec()\fP to dd (any number of digits)
456 .\" JOIN
457 \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP
458 or \fBpcre_dfa_exec()\fP; if used twice, pass the
460 .\" JOIN
461 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
462 (any number of digits)
463 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
464 \eS output details of memory get/free calls during matching
465 .\" JOIN
466 \eY pass the PCRE_NO_START_OPTIMIZE option to \fBpcre_exec()\fP
467 or \fBpcre_dfa_exec()\fP
468 .\" JOIN
469 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
470 or \fBpcre_dfa_exec()\fP
471 .\" JOIN
472 \e? pass the PCRE_NO_UTF8_CHECK option to
473 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
474 .\" JOIN
475 \e>dd start the match at offset dd (optional "-"; then
476 any number of digits); this sets the \fIstartoffset\fP
477 argument for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
478 .\" JOIN
479 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
480 or \fBpcre_dfa_exec()\fP
481 .\" JOIN
482 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
483 or \fBpcre_dfa_exec()\fP
484 .\" JOIN
485 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
486 or \fBpcre_dfa_exec()\fP
487 .\" JOIN
488 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
489 or \fBpcre_dfa_exec()\fP
490 .\" JOIN
491 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
492 or \fBpcre_dfa_exec()\fP
493 .sp
494 Note that \exhh always specifies one byte, even in UTF-8 mode; this makes it
495 possible to construct invalid UTF-8 sequences for testing purposes. On the
496 other hand, \ex{hh} is interpreted as a UTF-8 character in UTF-8 mode,
497 generating more than one byte if the value is greater than 127. When not in
498 UTF-8 mode, it generates one byte for values less than 256, and causes an error
499 for greater values.
500 .P
501 The escapes that specify line ending sequences are literal strings, exactly as
502 shown. No more than one newline setting should be present in any data line.
503 .P
504 A backslash followed by anything else just escapes the anything else. If
505 the very last character is a backslash, it is ignored. This gives a way of
506 passing an empty line as data, since a real empty line terminates the data
507 input.
508 .P
509 The \fB\eJ\fP escape provides a way of setting the maximum stack size that is
510 used by the just-in-time optimization code. It is ignored if JIT optimization
511 is not being used. Providing a stack that is larger than the default 32K is
512 necessary only for very complicated patterns.
513 .P
514 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
515 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
516 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
517 numbers for each parameter that allow \fBpcre_exec()\fP to complete without
518 error. Because this is testing a specific feature of the normal interpretive
519 \fBpcre_exec()\fP execution, the use of any JIT optimization that might have
520 been set up by the \fB/S+\fP qualifier of \fB-s+\fP option is disabled.
521 .P
522 The \fImatch_limit\fP number is a measure of the amount of backtracking
523 that takes place, and checking it out can be instructive. For most simple
524 matches, the number is quite small, but for patterns with very large numbers of
525 matching possibilities, it can become large very quickly with increasing length
526 of subject string. The \fImatch_limit_recursion\fP number is a measure of how
527 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is
528 needed to complete the match attempt.
529 .P
530 When \eO is used, the value specified may be higher or lower than the size set
531 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
532 the call of \fBpcre_exec()\fP for the line in which it appears.
533 .P
534 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
535 API to be used, the only option-setting sequences that have any effect are \eB,
536 \eN, and \eZ, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
537 to be passed to \fBregexec()\fP.
538 .P
539 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
540 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
541 any number of hexadecimal digits inside the braces. The result is from one to
542 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
543 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
544 valid Unicode code points, or indeed valid UTF-8 characters according to the
545 later rules in RFC 3629.
546 .
547 .
549 .rs
550 .sp
551 By default, \fBpcretest\fP uses the standard PCRE matching function,
552 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
553 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
554 different way, and has some restrictions. The differences between the two
555 functions are described in the
556 .\" HREF
557 \fBpcrematching\fP
558 .\"
559 documentation.
560 .P
561 If a data line contains the \eD escape sequence, or if the command line
562 contains the \fB-dfa\fP option, the alternative matching function is called.
563 This function finds all possible matches at a given point. If, however, the \eF
564 escape sequence is present in the data line, it stops after the first match is
565 found. This is always the shortest possible match.
566 .
567 .
569 .rs
570 .sp
571 This section describes the output when the normal matching function,
572 \fBpcre_exec()\fP, is being used.
573 .P
574 When a match succeeds, \fBpcretest\fP outputs the list of captured substrings
575 that \fBpcre_exec()\fP returns, starting with number 0 for the string that
576 matched the whole pattern. Otherwise, it outputs "No match" when the return is
577 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
578 substring when \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL. (Note that this is
579 the entire substring that was inspected during the partial match; it may
580 include characters before the actual match start if a lookbehind assertion,
581 \eK, \eb, or \eB was involved.) For any other return, \fBpcretest\fP outputs
582 the PCRE negative error number and a short descriptive phrase. If the error is
583 a failed UTF-8 string check, the byte offset of the start of the failing
584 character and the reason code are also output, provided that the size of the
585 output vector is at least two. Here is an example of an interactive
586 \fBpcretest\fP run.
587 .sp
588 $ pcretest
589 PCRE version 8.13 2011-04-30
590 .sp
591 re> /^abc(\ed+)/
592 data> abc123
593 0: abc123
594 1: 123
595 data> xyz
596 No match
597 .sp
598 Unset capturing substrings that are not followed by one that is set are not
599 returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In the
600 following example, there are two capturing substrings, but when the first data
601 line is matched, the second, unset substring is not shown. An "internal" unset
602 substring is shown as "<unset>", as for the second data line.
603 .sp
604 re> /(a)|(b)/
605 data> a
606 0: a
607 1: a
608 data> b
609 0: b
610 1: <unset>
611 2: b
612 .sp
613 If the strings contain any non-printing characters, they are output as \e0x
614 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
615 pattern. See below for the definition of non-printing characters. If the
616 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
617 the the rest of the subject string, identified by "0+" like this:
618 .sp
619 re> /cat/+
620 data> cataract
621 0: cat
622 0+ aract
623 .sp
624 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
625 matching attempts are output in sequence, like this:
626 .sp
627 re> /\eBi(\ew\ew)/g
628 data> Mississippi
629 0: iss
630 1: ss
631 0: iss
632 1: ss
633 0: ipp
634 1: pp
635 .sp
636 "No match" is output only if the first match attempt fails. Here is an example
637 of a failure message (the offset 4 that is specified by \e>4 is past the end of
638 the subject string):
639 .sp
640 re> /xyz/
641 data> xyz\e>4
642 Error -24 (bad offset value)
643 .P
644 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
645 data line that is successfully matched, the substrings extracted by the
646 convenience functions are output with C, G, or L after the string number
647 instead of a colon. This is in addition to the normal full list. The string
648 length (that is, the return from the extraction function) is given in
649 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
650 .P
651 Note that whereas patterns can be continued over several lines (a plain ">"
652 prompt is used for continuations), data lines may not. However newlines can be
653 included in data by means of the \en escape (or \er, \er\en, etc., depending on
654 the newline sequence setting).
655 .
656 .
657 .
659 .rs
660 .sp
661 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
662 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
663 output consists of a list of all the matches that start at the first point in
664 the subject where there is at least one match. For example:
665 .sp
666 re> /(tang|tangerine|tan)/
667 data> yellow tangerine\eD
668 0: tangerine
669 1: tang
670 2: tan
671 .sp
672 (Using the normal matching function on this data finds only "tang".) The
673 longest matching string is always given first (and numbered zero). After a
674 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
675 partially matching substring. (Note that this is the entire substring that was
676 inspected during the partial match; it may include characters before the actual
677 match start if a lookbehind assertion, \eK, \eb, or \eB was involved.)
678 .P
679 If \fB/g\fP is present on the pattern, the search for further matches resumes
680 at the end of the longest match. For example:
681 .sp
682 re> /(tang|tangerine|tan)/g
683 data> yellow tangerine and tangy sultana\eD
684 0: tangerine
685 1: tang
686 2: tan
687 0: tang
688 1: tan
689 0: tan
690 .sp
691 Since the matching function does not support substring capture, the escape
692 sequences that are concerned with captured substrings are not relevant.
693 .
694 .
696 .rs
697 .sp
698 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
699 indicating that the subject partially matched the pattern, you can restart the
700 match with additional subject data by means of the \eR escape sequence. For
701 example:
702 .sp
703 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
704 data> 23ja\eP\eD
705 Partial match: 23ja
706 data> n05\eR\eD
707 0: n05
708 .sp
709 For further information about partial matching, see the
710 .\" HREF
711 \fBpcrepartial\fP
712 .\"
713 documentation.
714 .
715 .
717 .rs
718 .sp
719 If the pattern contains any callout requests, \fBpcretest\fP's callout function
720 is called during matching. This works with both matching functions. By default,
721 the called function displays the callout number, the start and current
722 positions in the text at the callout time, and the next pattern item to be
723 tested. For example, the output
724 .sp
725 --->pqrabcdef
726 0 ^ ^ \ed
727 .sp
728 indicates that callout number 0 occurred for a match attempt starting at the
729 fourth character of the subject string, when the pointer was at the seventh
730 character of the data, and when the next pattern item was \ed. Just one
731 circumflex is output if the start and current positions are the same.
732 .P
733 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
734 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
735 callout number, the offset in the pattern, preceded by a plus, is output. For
736 example:
737 .sp
738 re> /\ed?[A-E]\e*/C
739 data> E*
740 --->E*
741 +0 ^ \ed?
742 +3 ^ [A-E]
743 +8 ^^ \e*
744 +10 ^ ^
745 0: E*
746 .sp
747 If a pattern contains (*MARK) items, an additional line is output whenever
748 a change of latest mark is passed to the callout function. For example:
749 .sp
750 re> /a(*MARK:X)bc/C
751 data> abc
752 --->abc
753 +0 ^ a
754 +1 ^^ (*MARK:X)
755 +10 ^^ b
756 Latest Mark: X
757 +11 ^ ^ c
758 +12 ^ ^
759 0: abc
760 .sp
761 The mark changes between matching "a" and "b", but stays the same for the rest
762 of the match, so nothing more is output. If, as a result of backtracking, the
763 mark reverts to being unset, the text "<unset>" is output.
764 .P
765 The callout function in \fBpcretest\fP returns zero (carry on matching) by
766 default, but you can use a \eC item in a data line (as described above) to
767 change this and other parameters of the callout.
768 .P
769 Inserting callouts can be helpful when using \fBpcretest\fP to check
770 complicated regular expressions. For further information about callouts, see
771 the
772 .\" HREF
773 \fBpcrecallout\fP
774 .\"
775 documentation.
776 .
777 .
778 .
780 .rs
781 .sp
782 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
783 bytes other than 32-126 are always treated as non-printing characters are are
784 therefore shown as hex escapes.
785 .P
786 When \fBpcretest\fP is outputting text that is a matched part of a subject
787 string, it behaves in the same way, unless a different locale has been set for
788 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
789 function to distinguish printing and non-printing characters.
790 .
791 .
792 .
794 .rs
795 .sp
796 The facilities described in this section are not available when the POSIX
797 interface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
798 specified.
799 .P
800 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
801 compiled pattern to a file, by following the modifiers with > and a file name.
802 For example:
803 .sp
804 /pattern/im >/some/file
805 .sp
806 See the
807 .\" HREF
808 \fBpcreprecompile\fP
809 .\"
810 documentation for a discussion about saving and re-using compiled patterns.
811 Note that if the pattern was successfully studied with JIT optimization, the
812 JIT data cannot be saved.
813 .P
814 The data that is written is binary. The first eight bytes are the length of the
815 compiled pattern data followed by the length of the optional study data, each
816 written as four bytes in big-endian order (most significant byte first). If
817 there is no study data (either the pattern was not studied, or studying did not
818 return any data), the second length is zero. The lengths are followed by an
819 exact copy of the compiled pattern. If there is additional study data, this
820 (excluding any JIT data) follows immediately after the compiled pattern. After
821 writing the file, \fBpcretest\fP expects to read a new pattern.
822 .P
823 A saved pattern can be reloaded into \fBpcretest\fP by specifying < and a file
824 name instead of a pattern. The name of the file must not contain a < character,
825 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
826 characters.
827 For example:
828 .sp
829 re> </some/file
830 Compiled pattern loaded from /some/file
831 No study data
832 .sp
833 If the pattern was previously studied with the JIT optimization, the JIT
834 information cannot be saved and restored, and so is lost. When the pattern has
835 been loaded, \fBpcretest\fP proceeds to read data lines in the usual way.
836 .P
837 You can copy a file written by \fBpcretest\fP to a different host and reload it
838 there, even if the new host has opposite endianness to the one on which the
839 pattern was compiled. For example, you can compile on an i86 machine and run on
840 a SPARC machine.
841 .P
842 File names for saving and reloading can be absolute or relative, but note that
843 the shell facility of expanding a file name that starts with a tilde (~) is not
844 available.
845 .P
846 The ability to save and reload files in \fBpcretest\fP is intended for testing
847 and experimentation. It is not intended for production use because only a
848 single pattern can be written to a file. Furthermore, there is no facility for
849 supplying custom character tables for use with a reloaded pattern. If the
850 original pattern was compiled with custom tables, an attempt to match a subject
851 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
852 Finally, if you attempt to load a file that is not in the correct format, the
853 result is undefined.
854 .
855 .
856 .SH "SEE ALSO"
857 .rs
858 .sp
859 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrejit\fP,
860 \fBpcrematching\fP(3), \fBpcrepartial\fP(d), \fBpcrepattern\fP(3),
861 \fBpcreprecompile\fP(3).
862 .
863 .
865 .rs
866 .sp
867 .nf
868 Philip Hazel
869 University Computing Service
870 Cambridge CB2 3QH, England.
871 .fi
872 .
873 .
875 .rs
876 .sp
877 .nf
878 Last updated: 26 August 2011
879 Copyright (c) 1997-2011 University of Cambridge.
880 .fi


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