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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 Behave as if each data line contains the \eM escape sequence; this causes
54 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
55 calling \fBpcre_exec()\fP repeatedly with different limits.
56 .TP 10
57 \fB-m\fP
58 Output the size of each compiled pattern after it has been compiled. This is
59 equivalent to adding \fB/M\fP to each regular expression. For compatibility
60 with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
61 .TP 10
62 \fB-o\fP \fIosize\fP
63 Set the number of elements in the output vector that is used when calling
64 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
65 is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
66 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
67 changed for individual matching calls by including \eO in the data line (see
68 below).
69 .TP 10
70 \fB-p\fP
71 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
72 used to call PCRE. None of the other options has any effect when \fB-p\fP is
73 set.
74 .TP 10
75 \fB-q\fP
76 Do not output the version number of \fBpcretest\fP at the start of execution.
77 .TP 10
78 \fB-S\fP \fIsize\fP
79 On Unix-like systems, set the size of the runtime stack to \fIsize\fP
80 megabytes.
81 .TP 10
82 \fB-t\fP
83 Run each compile, study, and match many times with a timer, and output
84 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
85 \fB-t\fP, because you will then get the size output a zillion times, and the
86 timing will be distorted. You can control the number of iterations that are
87 used for timing by following \fB-t\fP with a number (as a separate item on the
88 command line). For example, "-t 1000" would iterate 1000 times. The default is
89 to iterate 500000 times.
90 .TP 10
91 \fB-tm\fP
92 This is like \fB-t\fP except that it times only the matching phase, not the
93 compile or study phases.
94 .
95 .
96 .SH DESCRIPTION
97 .rs
98 .sp
99 If \fBpcretest\fP is given two filename arguments, it reads from the first and
100 writes to the second. If it is given only one filename argument, it reads from
101 that file and writes to stdout. Otherwise, it reads from stdin and writes to
102 stdout, and prompts for each line of input, using "re>" to prompt for regular
103 expressions, and "data>" to prompt for data lines.
104 .P
105 When \fBpcretest\fP is built, a configuration option can specify that it should
106 be linked with the \fBlibreadline\fP library. When this is done, if the input
107 is from a terminal, it is read using the \fBreadline()\fP function. This
108 provides line-editing and history facilities. The output from the \fB-help\fP
109 option states whether or not \fBreadline()\fP will be used.
110 .P
111 The program handles any number of sets of input on a single input file. Each
112 set starts with a regular expression, and continues with any number of data
113 lines to be matched against the pattern.
114 .P
115 Each data line is matched separately and independently. If you want to do
116 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
117 etc., depending on the newline setting) in a single line of input to encode the
118 newline sequences. There is no limit on the length of data lines; the input
119 buffer is automatically extended if it is too small.
120 .P
121 An empty line signals the end of the data lines, at which point a new regular
122 expression is read. The regular expressions are given enclosed in any
123 non-alphanumeric delimiters other than backslash, for example:
124 .sp
125 /(a|bc)x+yz/
126 .sp
127 White space before the initial delimiter is ignored. A regular expression may
128 be continued over several input lines, in which case the newline characters are
129 included within it. It is possible to include the delimiter within the pattern
130 by escaping it, for example
131 .sp
132 /abc\e/def/
133 .sp
134 If you do so, the escape and the delimiter form part of the pattern, but since
135 delimiters are always non-alphanumeric, this does not affect its interpretation.
136 If the terminating delimiter is immediately followed by a backslash, for
137 example,
138 .sp
139 /abc/\e
140 .sp
141 then a backslash is added to the end of the pattern. This is done to provide a
142 way of testing the error condition that arises if a pattern finishes with a
143 backslash, because
144 .sp
145 /abc\e/
146 .sp
147 is interpreted as the first line of a pattern that starts with "abc/", causing
148 pcretest to read the next line as a continuation of the regular expression.
149 .
150 .
151 .SH "PATTERN MODIFIERS"
152 .rs
153 .sp
154 A pattern may be followed by any number of modifiers, which are mostly single
155 characters. Following Perl usage, these are referred to below as, for example,
156 "the \fB/i\fP modifier", even though the delimiter of the pattern need not
157 always be a slash, and no slash is used when writing modifiers. Whitespace may
158 appear between the final pattern delimiter and the first modifier, and between
159 the modifiers themselves.
160 .P
161 The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
162 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
163 \fBpcre_compile()\fP is called. These four modifier letters have the same
164 effect as they do in Perl. For example:
165 .sp
166 /caseless/i
167 .sp
168 The following table shows additional modifiers for setting PCRE compile-time
169 options that do not correspond to anything in Perl:
170 .sp
171 \fB/8\fP PCRE_UTF8
172 \fB/?\fP PCRE_NO_UTF8_CHECK
173 \fB/A\fP PCRE_ANCHORED
174 \fB/C\fP PCRE_AUTO_CALLOUT
175 \fB/E\fP PCRE_DOLLAR_ENDONLY
176 \fB/f\fP PCRE_FIRSTLINE
177 \fB/J\fP PCRE_DUPNAMES
178 \fB/N\fP PCRE_NO_AUTO_CAPTURE
179 \fB/U\fP PCRE_UNGREEDY
180 \fB/W\fP PCRE_UCP
181 \fB/X\fP PCRE_EXTRA
182 \fB/Y\fP PCRE_NO_START_OPTIMIZE
183 \fB/<JS>\fP PCRE_JAVASCRIPT_COMPAT
184 \fB/<cr>\fP PCRE_NEWLINE_CR
185 \fB/<lf>\fP PCRE_NEWLINE_LF
186 \fB/<crlf>\fP PCRE_NEWLINE_CRLF
187 \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
188 \fB/<any>\fP PCRE_NEWLINE_ANY
189 \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
190 \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
191 .sp
192 The modifiers that are enclosed in angle brackets are literal strings as shown,
193 including the angle brackets, but the letters can be in either case. This
194 example sets multiline matching with CRLF as the line ending sequence:
195 .sp
196 /^abc/m<crlf>
197 .sp
198 As well as turning on the PCRE_UTF8 option, the \fB/8\fP modifier also causes
199 any non-printing characters in output strings to be printed using the
200 \ex{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
201 options are given in the
202 .\" HREF
203 \fBpcreapi\fP
204 .\"
205 documentation.
206 .
207 .
208 .SS "Finding all matches in a string"
209 .rs
210 .sp
211 Searching for all possible matches within each subject string can be requested
212 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
213 again to search the remainder of the subject string. The difference between
214 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
215 \fBpcre_exec()\fP to start searching at a new point within the entire string
216 (which is in effect what Perl does), whereas the latter passes over a shortened
217 substring. This makes a difference to the matching process if the pattern
218 begins with a lookbehind assertion (including \eb or \eB).
219 .P
220 If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
221 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
222 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
223 same point. If this second match fails, the start offset is advanced, and the
224 normal match is retried. This imitates the way Perl handles such cases when
225 using the \fB/g\fP modifier or the \fBsplit()\fP function. Normally, the start
226 offset is advanced by one character, but if the newline convention recognizes
227 CRLF as a newline, and the current character is CR followed by LF, an advance
228 of two is used.
229 .
230 .
231 .SS "Other modifiers"
232 .rs
233 .sp
234 There are yet more modifiers for controlling the way \fBpcretest\fP
235 operates.
236 .P
237 The \fB/+\fP modifier requests that as well as outputting the substring that
238 matched the entire pattern, pcretest should in addition output the remainder of
239 the subject string. This is useful for tests where the subject contains
240 multiple copies of the same substring.
241 .P
242 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
243 output a representation of the compiled byte code after compilation. Normally
244 this information contains length and offset values; however, if \fB/Z\fP is
245 also present, this data is replaced by spaces. This is a special feature for
246 use in the automatic test scripts; it ensures that the same output is generated
247 for different internal link sizes.
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/I\fP modifier requests that \fBpcretest\fP output information about the
261 compiled pattern (whether it is anchored, has a fixed first character, and
262 so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
263 pattern. If the pattern is studied, the results of that are also output.
264 .P
265 The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking
266 control verbs that are returned from calls to \fBpcre_exec()\fP. It causes
267 \fBpcretest\fP to create a \fBpcre_extra\fP block if one has not already been
268 created by a call to \fBpcre_study()\fP, and to set the PCRE_EXTRA_MARK flag
269 and the \fBmark\fP field within it, every time that \fBpcre_exec()\fP is
270 called. If the variable that the \fBmark\fP field points to is non-NULL for a
271 match, non-match, or partial match, \fBpcretest\fP prints the string to which
272 it points. For a match, this is shown on a line by itself, tagged with "MK:".
273 For a non-match it is added to the message.
274 .P
275 The \fB/L\fP modifier must be followed directly by the name of a locale, for
276 example,
277 .sp
278 /pattern/Lfr_FR
279 .sp
280 For this reason, it must be the last modifier. The given locale is set,
281 \fBpcre_maketables()\fP is called to build a set of character tables for the
282 locale, and this is then passed to \fBpcre_compile()\fP when compiling the
283 regular expression. Without an \fB/L\fP (or \fB/T\fP) modifier, NULL is passed
284 as the tables pointer; that is, \fB/L\fP applies only to the expression on
285 which it appears.
286 .P
287 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
288 pattern to be output.
289 .P
290 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
291 expression has been compiled, and the results used when the expression is
292 matched.
293 .P
294 The \fB/T\fP modifier must be followed by a single digit. It causes a specific
295 set of built-in character tables to be passed to \fBpcre_compile()\fP. It is
296 used in the standard PCRE tests to check behaviour with different character
297 tables. The digit specifies the tables as follows:
298 .sp
299 0 the default ASCII tables, as distributed in
300 pcre_chartables.c.dist
301 1 a set of tables defining ISO 8859 characters
302 .sp
303 In table 1, some characters whose codes are greater than 128 are identified as
304 letters, digits, spaces, etc.
305 .
306 .
307 .SS "Using the POSIX wrapper API"
308 .rs
309 .sp
310 The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
311 API rather than its native API. When \fB/P\fP is set, the following modifiers
312 set options for the \fBregcomp()\fP function:
313 .sp
314 /i REG_ICASE
315 /m REG_NEWLINE
316 /N REG_NOSUB
317 /s REG_DOTALL )
318 /U REG_UNGREEDY ) These options are not part of
319 /W REG_UCP ) the POSIX standard
320 /8 REG_UTF8 )
321 .sp
322 The \fB/+\fP modifier works as described above. All other modifiers are
323 ignored.
324 .
325 .
326 .SH "DATA LINES"
327 .rs
328 .sp
329 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
330 whitespace is removed, and it is then scanned for \e escapes. Some of these are
331 pretty esoteric features, intended for checking out some of the more
332 complicated features of PCRE. If you are just testing "ordinary" regular
333 expressions, you probably don't need any of these. The following escapes are
334 recognized:
335 .sp
336 \ea alarm (BEL, \ex07)
337 \eb backspace (\ex08)
338 \ee escape (\ex27)
339 \ef formfeed (\ex0c)
340 \en newline (\ex0a)
341 .\" JOIN
342 \eqdd set the PCRE_MATCH_LIMIT limit to dd
343 (any number of digits)
344 \er carriage return (\ex0d)
345 \et tab (\ex09)
346 \ev vertical tab (\ex0b)
347 \ennn octal character (up to 3 octal digits)
348 always a byte unless > 255 in UTF-8 mode
349 \exhh hexadecimal byte (up to 2 hex digits)
350 .\" JOIN
351 \ex{hh...} hexadecimal character, any number of digits
352 in UTF-8 mode
353 .\" JOIN
354 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
355 or \fBpcre_dfa_exec()\fP
356 .\" JOIN
357 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
358 or \fBpcre_dfa_exec()\fP
359 .\" JOIN
360 \eCdd call pcre_copy_substring() for substring dd
361 after a successful match (number less than 32)
362 .\" JOIN
363 \eCname call pcre_copy_named_substring() for substring
364 "name" after a successful match (name termin-
365 ated by next non alphanumeric character)
366 .\" JOIN
367 \eC+ show the current captured substrings at callout
368 time
369 \eC- do not supply a callout function
370 .\" JOIN
371 \eC!n return 1 instead of 0 when callout number n is
372 reached
373 .\" JOIN
374 \eC!n!m return 1 instead of 0 when callout number n is
375 reached for the nth time
376 .\" JOIN
377 \eC*n pass the number n (may be negative) as callout
378 data; this is used as the callout return value
379 \eD use the \fBpcre_dfa_exec()\fP match function
380 \eF only shortest match for \fBpcre_dfa_exec()\fP
381 .\" JOIN
382 \eGdd call pcre_get_substring() for substring dd
383 after a successful match (number less than 32)
384 .\" JOIN
385 \eGname call pcre_get_named_substring() for substring
386 "name" after a successful match (name termin-
387 ated by next non-alphanumeric character)
388 .\" JOIN
389 \eL call pcre_get_substringlist() after a
390 successful match
391 .\" JOIN
392 \eM discover the minimum MATCH_LIMIT and
393 MATCH_LIMIT_RECURSION settings
394 .\" JOIN
395 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
396 or \fBpcre_dfa_exec()\fP; if used twice, pass the
397 PCRE_NOTEMPTY_ATSTART option
398 .\" JOIN
399 \eOdd set the size of the output vector passed to
400 \fBpcre_exec()\fP to dd (any number of digits)
401 .\" JOIN
402 \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP
403 or \fBpcre_dfa_exec()\fP; if used twice, pass the
404 PCRE_PARTIAL_HARD option
405 .\" JOIN
406 \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
407 (any number of digits)
408 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
409 \eS output details of memory get/free calls during matching
410 .\" JOIN
411 \eY pass the PCRE_NO_START_OPTIMIZE option to \fBpcre_exec()\fP
412 or \fBpcre_dfa_exec()\fP
413 .\" JOIN
414 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
415 or \fBpcre_dfa_exec()\fP
416 .\" JOIN
417 \e? pass the PCRE_NO_UTF8_CHECK option to
418 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
419 .\" JOIN
420 \e>dd start the match at offset dd (optional "-"; then
421 any number of digits); this sets the \fIstartoffset\fP
422 argument for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
423 .\" JOIN
424 \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
425 or \fBpcre_dfa_exec()\fP
426 .\" JOIN
427 \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
428 or \fBpcre_dfa_exec()\fP
429 .\" JOIN
430 \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
431 or \fBpcre_dfa_exec()\fP
432 .\" JOIN
433 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
434 or \fBpcre_dfa_exec()\fP
435 .\" JOIN
436 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
437 or \fBpcre_dfa_exec()\fP
438 .sp
439 Note that \exhh always specifies one byte, even in UTF-8 mode; this makes it
440 possible to construct invalid UTF-8 sequences for testing purposes. On the
441 other hand, \ex{hh} is interpreted as a UTF-8 character in UTF-8 mode,
442 generating more than one byte if the value is greater than 127. When not in
443 UTF-8 mode, it generates one byte for values less than 256, and causes an error
444 for greater values.
445 .P
446 The escapes that specify line ending sequences are literal strings, exactly as
447 shown. No more than one newline setting should be present in any data line.
448 .P
449 A backslash followed by anything else just escapes the anything else. If
450 the very last character is a backslash, it is ignored. This gives a way of
451 passing an empty line as data, since a real empty line terminates the data
452 input.
453 .P
454 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
455 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
456 fields of the \fBpcre_extra\fP data structure, until it finds the minimum
457 numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
458 \fImatch_limit\fP number is a measure of the amount of backtracking that takes
459 place, and checking it out can be instructive. For most simple matches, the
460 number is quite small, but for patterns with very large numbers of matching
461 possibilities, it can become large very quickly with increasing length of
462 subject string. The \fImatch_limit_recursion\fP number is a measure of how much
463 stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
464 to complete the match attempt.
465 .P
466 When \eO is used, the value specified may be higher or lower than the size set
467 by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
468 the call of \fBpcre_exec()\fP for the line in which it appears.
469 .P
470 If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
471 API to be used, the only option-setting sequences that have any effect are \eB,
472 \eN, and \eZ, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
473 to be passed to \fBregexec()\fP.
474 .P
475 The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
476 of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
477 any number of hexadecimal digits inside the braces. The result is from one to
478 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
479 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
480 valid Unicode code points, or indeed valid UTF-8 characters according to the
481 later rules in RFC 3629.
482 .
483 .
484 .SH "THE ALTERNATIVE MATCHING FUNCTION"
485 .rs
486 .sp
487 By default, \fBpcretest\fP uses the standard PCRE matching function,
488 \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
489 alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
490 different way, and has some restrictions. The differences between the two
491 functions are described in the
492 .\" HREF
493 \fBpcrematching\fP
494 .\"
495 documentation.
496 .P
497 If a data line contains the \eD escape sequence, or if the command line
498 contains the \fB-dfa\fP option, the alternative matching function is called.
499 This function finds all possible matches at a given point. If, however, the \eF
500 escape sequence is present in the data line, it stops after the first match is
501 found. This is always the shortest possible match.
502 .
503 .
504 .SH "DEFAULT OUTPUT FROM PCRETEST"
505 .rs
506 .sp
507 This section describes the output when the normal matching function,
508 \fBpcre_exec()\fP, is being used.
509 .P
510 When a match succeeds, pcretest outputs the list of captured substrings that
511 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
512 the whole pattern. Otherwise, it outputs "No match" when the return is
513 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
514 substring when \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL. (Note that this is
515 the entire substring that was inspected during the partial match; it may
516 include characters before the actual match start if a lookbehind assertion,
517 \eK, \eb, or \eB was involved.) For any other returns, it outputs the PCRE
518 negative error number. Here is an example of an interactive \fBpcretest\fP run.
519 .sp
520 $ pcretest
521 PCRE version 7.0 30-Nov-2006
522 .sp
523 re> /^abc(\ed+)/
524 data> abc123
525 0: abc123
526 1: 123
527 data> xyz
528 No match
529 .sp
530 Note that unset capturing substrings that are not followed by one that is set
531 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
532 the following example, there are two capturing substrings, but when the first
533 data line is matched, the second, unset substring is not shown. An "internal"
534 unset substring is shown as "<unset>", as for the second data line.
535 .sp
536 re> /(a)|(b)/
537 data> a
538 0: a
539 1: a
540 data> b
541 0: b
542 1: <unset>
543 2: b
544 .sp
545 If the strings contain any non-printing characters, they are output as \e0x
546 escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
547 pattern. See below for the definition of non-printing characters. If the
548 pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
549 the the rest of the subject string, identified by "0+" like this:
550 .sp
551 re> /cat/+
552 data> cataract
553 0: cat
554 0+ aract
555 .sp
556 If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
557 matching attempts are output in sequence, like this:
558 .sp
559 re> /\eBi(\ew\ew)/g
560 data> Mississippi
561 0: iss
562 1: ss
563 0: iss
564 1: ss
565 0: ipp
566 1: pp
567 .sp
568 "No match" is output only if the first match attempt fails.
569 .P
570 If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
571 data line that is successfully matched, the substrings extracted by the
572 convenience functions are output with C, G, or L after the string number
573 instead of a colon. This is in addition to the normal full list. The string
574 length (that is, the return from the extraction function) is given in
575 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
576 .P
577 Note that whereas patterns can be continued over several lines (a plain ">"
578 prompt is used for continuations), data lines may not. However newlines can be
579 included in data by means of the \en escape (or \er, \er\en, etc., depending on
580 the newline sequence setting).
581 .
582 .
583 .
584 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
585 .rs
586 .sp
587 When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
588 means of the \eD escape sequence or the \fB-dfa\fP command line option), the
589 output consists of a list of all the matches that start at the first point in
590 the subject where there is at least one match. For example:
591 .sp
592 re> /(tang|tangerine|tan)/
593 data> yellow tangerine\eD
594 0: tangerine
595 1: tang
596 2: tan
597 .sp
598 (Using the normal matching function on this data finds only "tang".) The
599 longest matching string is always given first (and numbered zero). After a
600 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
601 partially matching substring. (Note that this is the entire substring that was
602 inspected during the partial match; it may include characters before the actual
603 match start if a lookbehind assertion, \eK, \eb, or \eB was involved.)
604 .P
605 If \fB/g\fP is present on the pattern, the search for further matches resumes
606 at the end of the longest match. For example:
607 .sp
608 re> /(tang|tangerine|tan)/g
609 data> yellow tangerine and tangy sultana\eD
610 0: tangerine
611 1: tang
612 2: tan
613 0: tang
614 1: tan
615 0: tan
616 .sp
617 Since the matching function does not support substring capture, the escape
618 sequences that are concerned with captured substrings are not relevant.
619 .
620 .
621 .SH "RESTARTING AFTER A PARTIAL MATCH"
622 .rs
623 .sp
624 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
625 indicating that the subject partially matched the pattern, you can restart the
626 match with additional subject data by means of the \eR escape sequence. For
627 example:
628 .sp
629 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
630 data> 23ja\eP\eD
631 Partial match: 23ja
632 data> n05\eR\eD
633 0: n05
634 .sp
635 For further information about partial matching, see the
636 .\" HREF
637 \fBpcrepartial\fP
638 .\"
639 documentation.
640 .
641 .
642 .SH CALLOUTS
643 .rs
644 .sp
645 If the pattern contains any callout requests, \fBpcretest\fP's callout function
646 is called during matching. This works with both matching functions. By default,
647 the called function displays the callout number, the start and current
648 positions in the text at the callout time, and the next pattern item to be
649 tested. For example, the output
650 .sp
651 --->pqrabcdef
652 0 ^ ^ \ed
653 .sp
654 indicates that callout number 0 occurred for a match attempt starting at the
655 fourth character of the subject string, when the pointer was at the seventh
656 character of the data, and when the next pattern item was \ed. Just one
657 circumflex is output if the start and current positions are the same.
658 .P
659 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
660 result of the \fB/C\fP pattern modifier. In this case, instead of showing the
661 callout number, the offset in the pattern, preceded by a plus, is output. For
662 example:
663 .sp
664 re> /\ed?[A-E]\e*/C
665 data> E*
666 --->E*
667 +0 ^ \ed?
668 +3 ^ [A-E]
669 +8 ^^ \e*
670 +10 ^ ^
671 0: E*
672 .sp
673 The callout function in \fBpcretest\fP returns zero (carry on matching) by
674 default, but you can use a \eC item in a data line (as described above) to
675 change this.
676 .P
677 Inserting callouts can be helpful when using \fBpcretest\fP to check
678 complicated regular expressions. For further information about callouts, see
679 the
680 .\" HREF
681 \fBpcrecallout\fP
682 .\"
683 documentation.
684 .
685 .
686 .
687 .SH "NON-PRINTING CHARACTERS"
688 .rs
689 .sp
690 When \fBpcretest\fP is outputting text in the compiled version of a pattern,
691 bytes other than 32-126 are always treated as non-printing characters are are
692 therefore shown as hex escapes.
693 .P
694 When \fBpcretest\fP is outputting text that is a matched part of a subject
695 string, it behaves in the same way, unless a different locale has been set for
696 the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
697 function to distinguish printing and non-printing characters.
698 .
699 .
700 .
701 .SH "SAVING AND RELOADING COMPILED PATTERNS"
702 .rs
703 .sp
704 The facilities described in this section are not available when the POSIX
705 inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
706 specified.
707 .P
708 When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
709 compiled pattern to a file, by following the modifiers with > and a file name.
710 For example:
711 .sp
712 /pattern/im >/some/file
713 .sp
714 See the
715 .\" HREF
716 \fBpcreprecompile\fP
717 .\"
718 documentation for a discussion about saving and re-using compiled patterns.
719 .P
720 The data that is written is binary. The first eight bytes are the length of the
721 compiled pattern data followed by the length of the optional study data, each
722 written as four bytes in big-endian order (most significant byte first). If
723 there is no study data (either the pattern was not studied, or studying did not
724 return any data), the second length is zero. The lengths are followed by an
725 exact copy of the compiled pattern. If there is additional study data, this
726 follows immediately after the compiled pattern. After writing the file,
727 \fBpcretest\fP expects to read a new pattern.
728 .P
729 A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
730 name instead of a pattern. The name of the file must not contain a < character,
731 as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
732 characters.
733 For example:
734 .sp
735 re> </some/file
736 Compiled regex loaded from /some/file
737 No study data
738 .sp
739 When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
740 the usual way.
741 .P
742 You can copy a file written by \fBpcretest\fP to a different host and reload it
743 there, even if the new host has opposite endianness to the one on which the
744 pattern was compiled. For example, you can compile on an i86 machine and run on
745 a SPARC machine.
746 .P
747 File names for saving and reloading can be absolute or relative, but note that
748 the shell facility of expanding a file name that starts with a tilde (~) is not
749 available.
750 .P
751 The ability to save and reload files in \fBpcretest\fP is intended for testing
752 and experimentation. It is not intended for production use because only a
753 single pattern can be written to a file. Furthermore, there is no facility for
754 supplying custom character tables for use with a reloaded pattern. If the
755 original pattern was compiled with custom tables, an attempt to match a subject
756 string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
757 Finally, if you attempt to load a file that is not in the correct format, the
758 result is undefined.
759 .
760 .
761 .SH "SEE ALSO"
762 .rs
763 .sp
764 \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
765 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
766 .
767 .
768 .SH AUTHOR
769 .rs
770 .sp
771 .nf
772 Philip Hazel
773 University Computing Service
774 Cambridge CB2 3QH, England.
775 .fi
776 .
777 .
778 .SH REVISION
779 .rs
780 .sp
781 .nf
782 Last updated: 21 November 2010
783 Copyright (c) 1997-2010 University of Cambridge.
784 .fi

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