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1 nigel 73 PCRETEST(1) PCRETEST(1)
2 nigel 41
3    
4 nigel 73 NAME
5     pcretest - a program for testing Perl-compatible regular expressions.
6    
7 nigel 79
8 nigel 53 SYNOPSIS
9 nigel 41
10 nigel 91 pcretest [options] [source] [destination]
11 nigel 75
12 nigel 73 pcretest was written as a test program for the PCRE regular expression
13     library itself, but it can also be used for experimenting with regular
14     expressions. This document describes the features of the test program;
15     for details of the regular expressions themselves, see the pcrepattern
16 nigel 75 documentation. For details of the PCRE library function calls and their
17     options, see the pcreapi documentation.
18 nigel 41
19    
20 nigel 63 OPTIONS
21 nigel 41
22 nigel 93 -b Behave as if each regex has the /B (show bytecode) modifier;
23     the internal form is output after compilation.
24    
25 nigel 73 -C Output the version number of the PCRE library, and all avail-
26 nigel 93 able information about the optional features that are
27 nigel 73 included, and then exit.
28 nigel 63
29 nigel 93 -d Behave as if each regex has the /D (debug) modifier; the
30     internal form and information about the compiled pattern is
31     output after compilation; -d is equivalent to -b -i.
32 nigel 41
33 nigel 77 -dfa Behave as if each data line contains the \D escape sequence;
34     this causes the alternative matching function,
35     pcre_dfa_exec(), to be used instead of the standard
36     pcre_exec() function (more detail is given below).
37    
38 nigel 93 -help Output a brief summary these options and then exit.
39    
40 nigel 77 -i Behave as if each regex has the /I modifier; information
41 nigel 73 about the compiled pattern is given after compilation.
42 nigel 41
43 ph10 392 -M Behave as if each data line contains the \M escape sequence;
44     this causes PCRE to discover the minimum MATCH_LIMIT and
45     MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
46     edly with different limits.
47    
48     -m Output the size of each compiled pattern after it has been
49     compiled. This is equivalent to adding /M to each regular
50     expression. For compatibility with earlier versions of
51 nigel 73 pcretest, -s is a synonym for -m.
52 nigel 41
53 ph10 392 -o osize Set the number of elements in the output vector that is used
54     when calling pcre_exec() or pcre_dfa_exec() to be osize. The
55     default value is 45, which is enough for 14 capturing subex-
56     pressions for pcre_exec() or 22 different matches for
57     pcre_dfa_exec(). The vector size can be changed for individ-
58     ual matching calls by including \O in the data line (see
59 nigel 93 below).
60 nigel 41
61 ph10 392 -p Behave as if each regex has the /P modifier; the POSIX wrap-
62     per API is used to call PCRE. None of the other options has
63 nigel 77 any effect when -p is set.
64 nigel 41
65 ph10 392 -q Do not output the version number of pcretest at the start of
66 nigel 87 execution.
67    
68 ph10 392 -S size On Unix-like systems, set the size of the runtime stack to
69 nigel 91 size megabytes.
70    
71 ph10 392 -t Run each compile, study, and match many times with a timer,
72     and output resulting time per compile or match (in millisec-
73     onds). Do not set -m with -t, because you will then get the
74     size output a zillion times, and the timing will be dis-
75     torted. You can control the number of iterations that are
76     used for timing by following -t with a number (as a separate
77 nigel 93 item on the command line). For example, "-t 1000" would iter-
78     ate 1000 times. The default is to iterate 500000 times.
79 nigel 49
80 nigel 93 -tm This is like -t except that it times only the matching phase,
81     not the compile or study phases.
82 nigel 49
83 nigel 93
84 nigel 63 DESCRIPTION
85 nigel 41
86 ph10 392 If pcretest is given two filename arguments, it reads from the first
87 nigel 73 and writes to the second. If it is given only one filename argument, it
88 ph10 392 reads from that file and writes to stdout. Otherwise, it reads from
89     stdin and writes to stdout, and prompts for each line of input, using
90 nigel 73 "re>" to prompt for regular expressions, and "data>" to prompt for data
91     lines.
92 nigel 41
93 ph10 392 When pcretest is built, a configuration option can specify that it
94     should be linked with the libreadline library. When this is done, if
95 ph10 289 the input is from a terminal, it is read using the readline() function.
96 ph10 392 This provides line-editing and history facilities. The output from the
97 ph10 289 -help option states whether or not readline() will be used.
98    
99 nigel 73 The program handles any number of sets of input on a single input file.
100 ph10 392 Each set starts with a regular expression, and continues with any num-
101 nigel 73 ber of data lines to be matched against the pattern.
102 nigel 41
103 ph10 392 Each data line is matched separately and independently. If you want to
104 nigel 91 do multi-line matches, you have to use the \n escape sequence (or \r or
105 nigel 93 \r\n, etc., depending on the newline setting) in a single line of input
106 ph10 392 to encode the newline sequences. There is no limit on the length of
107     data lines; the input buffer is automatically extended if it is too
108 nigel 93 small.
109 nigel 63
110 ph10 392 An empty line signals the end of the data lines, at which point a new
111     regular expression is read. The regular expressions are given enclosed
112 nigel 91 in any non-alphanumeric delimiters other than backslash, for example:
113 nigel 63
114 nigel 73 /(a|bc)x+yz/
115 nigel 41
116 ph10 392 White space before the initial delimiter is ignored. A regular expres-
117     sion may be continued over several input lines, in which case the new-
118     line characters are included within it. It is possible to include the
119 nigel 73 delimiter within the pattern by escaping it, for example
120 nigel 41
121 nigel 73 /abc\/def/
122 nigel 41
123 ph10 392 If you do so, the escape and the delimiter form part of the pattern,
124     but since delimiters are always non-alphanumeric, this does not affect
125     its interpretation. If the terminating delimiter is immediately fol-
126 nigel 73 lowed by a backslash, for example,
127 nigel 41
128 nigel 73 /abc/\
129 nigel 41
130 ph10 392 then a backslash is added to the end of the pattern. This is done to
131     provide a way of testing the error condition that arises if a pattern
132 nigel 73 finishes with a backslash, because
133 nigel 49
134 nigel 73 /abc\/
135 nigel 49
136 ph10 392 is interpreted as the first line of a pattern that starts with "abc/",
137 nigel 73 causing pcretest to read the next line as a continuation of the regular
138     expression.
139 nigel 49
140 nigel 41
141 nigel 63 PATTERN MODIFIERS
142 nigel 41
143 ph10 392 A pattern may be followed by any number of modifiers, which are mostly
144     single characters. Following Perl usage, these are referred to below
145     as, for example, "the /i modifier", even though the delimiter of the
146     pattern need not always be a slash, and no slash is used when writing
147     modifiers. Whitespace may appear between the final pattern delimiter
148 nigel 75 and the first modifier, and between the modifiers themselves.
149 nigel 41
150 nigel 75 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
151 ph10 392 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
152     pile() is called. These four modifier letters have the same effect as
153 nigel 75 they do in Perl. For example:
154    
155 nigel 73 /caseless/i
156 nigel 41
157 nigel 75 The following table shows additional modifiers for setting PCRE options
158     that do not correspond to anything in Perl:
159 nigel 41
160 ph10 231 /A PCRE_ANCHORED
161     /C PCRE_AUTO_CALLOUT
162     /E PCRE_DOLLAR_ENDONLY
163     /f PCRE_FIRSTLINE
164     /J PCRE_DUPNAMES
165     /N PCRE_NO_AUTO_CAPTURE
166     /U PCRE_UNGREEDY
167     /X PCRE_EXTRA
168 ph10 345 /<JS> PCRE_JAVASCRIPT_COMPAT
169 ph10 231 /<cr> PCRE_NEWLINE_CR
170     /<lf> PCRE_NEWLINE_LF
171     /<crlf> PCRE_NEWLINE_CRLF
172     /<anycrlf> PCRE_NEWLINE_ANYCRLF
173     /<any> PCRE_NEWLINE_ANY
174     /<bsr_anycrlf> PCRE_BSR_ANYCRLF
175     /<bsr_unicode> PCRE_BSR_UNICODE
176 nigel 75
177 ph10 392 Those specifying line ending sequences are literal strings as shown,
178     but the letters can be in either case. This example sets multiline
179 ph10 227 matching with CRLF as the line ending sequence:
180 nigel 91
181 nigel 93 /^abc/m<crlf>
182    
183 ph10 392 Details of the meanings of these PCRE options are given in the pcreapi
184 nigel 93 documentation.
185    
186 nigel 91 Finding all matches in a string
187    
188 ph10 392 Searching for all possible matches within each subject string can be
189     requested by the /g or /G modifier. After finding a match, PCRE is
190 nigel 73 called again to search the remainder of the subject string. The differ-
191     ence between /g and /G is that the former uses the startoffset argument
192 ph10 392 to pcre_exec() to start searching at a new point within the entire
193     string (which is in effect what Perl does), whereas the latter passes
194     over a shortened substring. This makes a difference to the matching
195 nigel 73 process if the pattern begins with a lookbehind assertion (including \b
196     or \B).
197 nigel 49
198 ph10 392 If any call to pcre_exec() in a /g or /G sequence matches an empty
199 ph10 453 string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
200     PCRE_ANCHORED flags set in order to search for another, non-empty,
201     match at the same point. If this second match fails, the start offset
202     is advanced by one character, and the normal match is retried. This
203     imitates the way Perl handles such cases when using the /g modifier or
204     the split() function.
205 nigel 49
206 nigel 91 Other modifiers
207    
208 nigel 75 There are yet more modifiers for controlling the way pcretest operates.
209 nigel 49
210 ph10 453 The /+ modifier requests that as well as outputting the substring that
211     matched the entire pattern, pcretest should in addition output the
212     remainder of the subject string. This is useful for tests where the
213 nigel 73 subject contains multiple copies of the same substring.
214 nigel 41
215 ph10 453 The /B modifier is a debugging feature. It requests that pcretest out-
216     put a representation of the compiled byte code after compilation. Nor-
217     mally this information contains length and offset values; however, if
218     /Z is also present, this data is replaced by spaces. This is a special
219 ph10 123 feature for use in the automatic test scripts; it ensures that the same
220     output is generated for different internal link sizes.
221 nigel 93
222 ph10 453 The /L modifier must be followed directly by the name of a locale, for
223 nigel 73 example,
224 nigel 41
225 nigel 75 /pattern/Lfr_FR
226 nigel 41
227 nigel 75 For this reason, it must be the last modifier. The given locale is set,
228 ph10 453 pcre_maketables() is called to build a set of character tables for the
229     locale, and this is then passed to pcre_compile() when compiling the
230     regular expression. Without an /L modifier, NULL is passed as the
231     tables pointer; that is, /L applies only to the expression on which it
232 nigel 75 appears.
233 nigel 41
234 ph10 453 The /I modifier requests that pcretest output information about the
235     compiled pattern (whether it is anchored, has a fixed first character,
236     and so on). It does this by calling pcre_fullinfo() after compiling a
237     pattern. If the pattern is studied, the results of that are also out-
238 nigel 75 put.
239 nigel 63
240 ph10 453 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
241 nigel 93 that is, both the /B and the /I modifiers.
242 nigel 41
243 nigel 75 The /F modifier causes pcretest to flip the byte order of the fields in
244 ph10 453 the compiled pattern that contain 2-byte and 4-byte numbers. This
245     facility is for testing the feature in PCRE that allows it to execute
246 nigel 75 patterns that were compiled on a host with a different endianness. This
247 ph10 453 feature is not available when the POSIX interface to PCRE is being
248     used, that is, when the /P pattern modifier is specified. See also the
249 nigel 75 section about saving and reloading compiled patterns below.
250    
251 ph10 453 The /S modifier causes pcre_study() to be called after the expression
252 nigel 73 has been compiled, and the results used when the expression is matched.
253 nigel 41
254 ph10 453 The /M modifier causes the size of memory block used to hold the com-
255 nigel 73 piled pattern to be output.
256 nigel 41
257 ph10 453 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
258     rather than its native API. When this is done, all other modifiers
259     except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
260     and REG_NEWLINE is set if /m is present. The wrapper functions force
261 ph10 392 PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
262 nigel 41
263 ph10 453 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
264     set. This turns on support for UTF-8 character handling in PCRE, pro-
265     vided that it was compiled with this support enabled. This modifier
266 nigel 73 also causes any non-printing characters in output strings to be printed
267     using the \x{hh...} notation if they are valid UTF-8 sequences.
268 nigel 41
269 ph10 453 If the /? modifier is used with /8, it causes pcretest to call
270     pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
271 nigel 73 checking of the string for UTF-8 validity.
272 nigel 41
273 nigel 71
274 nigel 53 DATA LINES
275 nigel 63
276 ph10 453 Before each data line is passed to pcre_exec(), leading and trailing
277     whitespace is removed, and it is then scanned for \ escapes. Some of
278     these are pretty esoteric features, intended for checking out some of
279     the more complicated features of PCRE. If you are just testing "ordi-
280     nary" regular expressions, you probably don't need any of these. The
281 nigel 73 following escapes are recognized:
282 nigel 49
283 nigel 93 \a alarm (BEL, \x07)
284     \b backspace (\x08)
285     \e escape (\x27)
286     \f formfeed (\x0c)
287     \n newline (\x0a)
288 nigel 91 \qdd set the PCRE_MATCH_LIMIT limit to dd
289     (any number of digits)
290 nigel 93 \r carriage return (\x0d)
291     \t tab (\x09)
292     \v vertical tab (\x0b)
293 nigel 73 \nnn octal character (up to 3 octal digits)
294     \xhh hexadecimal character (up to 2 hex digits)
295     \x{hh...} hexadecimal character, any number of digits
296     in UTF-8 mode
297     \A pass the PCRE_ANCHORED option to pcre_exec()
298 nigel 91 or pcre_dfa_exec()
299 nigel 73 \B pass the PCRE_NOTBOL option to pcre_exec()
300 nigel 91 or pcre_dfa_exec()
301 nigel 73 \Cdd call pcre_copy_substring() for substring dd
302 nigel 75 after a successful match (number less than 32)
303 nigel 73 \Cname call pcre_copy_named_substring() for substring
304     "name" after a successful match (name termin-
305     ated by next non alphanumeric character)
306     \C+ show the current captured substrings at callout
307     time
308     \C- do not supply a callout function
309     \C!n return 1 instead of 0 when callout number n is
310     reached
311     \C!n!m return 1 instead of 0 when callout number n is
312     reached for the nth time
313     \C*n pass the number n (may be negative) as callout
314 nigel 75 data; this is used as the callout return value
315 nigel 77 \D use the pcre_dfa_exec() match function
316     \F only shortest match for pcre_dfa_exec()
317 nigel 73 \Gdd call pcre_get_substring() for substring dd
318 nigel 75 after a successful match (number less than 32)
319 nigel 73 \Gname call pcre_get_named_substring() for substring
320     "name" after a successful match (name termin-
321     ated by next non-alphanumeric character)
322     \L call pcre_get_substringlist() after a
323     successful match
324 nigel 87 \M discover the minimum MATCH_LIMIT and
325     MATCH_LIMIT_RECURSION settings
326 nigel 73 \N pass the PCRE_NOTEMPTY option to pcre_exec()
327 ph10 453 or pcre_dfa_exec(); if used twice, pass the
328     PCRE_NOTEMPTY_ATSTART option
329 nigel 73 \Odd set the size of the output vector passed to
330 nigel 75 pcre_exec() to dd (any number of digits)
331 ph10 429 \P pass the PCRE_PARTIAL_SOFT option to pcre_exec()
332     or pcre_dfa_exec(); if used twice, pass the
333     PCRE_PARTIAL_HARD option
334 nigel 91 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
335     (any number of digits)
336 nigel 77 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
337 nigel 73 \S output details of memory get/free calls during matching
338 ph10 461 \Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
339     or pcre_dfa_exec()
340 nigel 73 \Z pass the PCRE_NOTEOL option to pcre_exec()
341 nigel 91 or pcre_dfa_exec()
342 nigel 73 \? pass the PCRE_NO_UTF8_CHECK option to
343 nigel 91 pcre_exec() or pcre_dfa_exec()
344 nigel 75 \>dd start the match at offset dd (any number of digits);
345     this sets the startoffset argument for pcre_exec()
346 nigel 91 or pcre_dfa_exec()
347     \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
348     or pcre_dfa_exec()
349     \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
350     or pcre_dfa_exec()
351     \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
352     or pcre_dfa_exec()
353 ph10 150 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
354     or pcre_dfa_exec()
355 nigel 93 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
356     or pcre_dfa_exec()
357 nigel 71
358 ph10 453 The escapes that specify line ending sequences are literal strings,
359 nigel 93 exactly as shown. No more than one newline setting should be present in
360     any data line.
361 nigel 75
362 ph10 453 A backslash followed by anything else just escapes the anything else.
363     If the very last character is a backslash, it is ignored. This gives a
364     way of passing an empty line as data, since a real empty line termi-
365 nigel 93 nates the data input.
366    
367 ph10 453 If \M is present, pcretest calls pcre_exec() several times, with dif-
368     ferent values in the match_limit and match_limit_recursion fields of
369     the pcre_extra data structure, until it finds the minimum numbers for
370 nigel 87 each parameter that allow pcre_exec() to complete. The match_limit num-
371 ph10 453 ber is a measure of the amount of backtracking that takes place, and
372 nigel 87 checking it out can be instructive. For most simple matches, the number
373 ph10 453 is quite small, but for patterns with very large numbers of matching
374     possibilities, it can become large very quickly with increasing length
375 nigel 87 of subject string. The match_limit_recursion number is a measure of how
376 ph10 453 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
377 nigel 87 memory is needed to complete the match attempt.
378 nigel 41
379 ph10 453 When \O is used, the value specified may be higher or lower than the
380 nigel 75 size set by the -O command line option (or defaulted to 45); \O applies
381     only to the call of pcre_exec() for the line in which it appears.
382 nigel 63
383 ph10 453 If the /P modifier was present on the pattern, causing the POSIX wrap-
384     per API to be used, the only option-setting sequences that have any
385     effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
386 nigel 87 to be passed to regexec().
387 nigel 41
388 ph10 453 The use of \x{hh...} to represent UTF-8 characters is not dependent on
389     the use of the /8 modifier on the pattern. It is recognized always.
390     There may be any number of hexadecimal digits inside the braces. The
391     result is from one to six bytes, encoded according to the original
392     UTF-8 rules of RFC 2279. This allows for values in the range 0 to
393     0x7FFFFFFF. Note that not all of those are valid Unicode code points,
394     or indeed valid UTF-8 characters according to the later rules in RFC
395 ph10 211 3629.
396 nigel 41
397 nigel 53
398 nigel 77 THE ALTERNATIVE MATCHING FUNCTION
399 nigel 53
400 ph10 453 By default, pcretest uses the standard PCRE matching function,
401 nigel 77 pcre_exec() to match each data line. From release 6.0, PCRE supports an
402 ph10 453 alternative matching function, pcre_dfa_test(), which operates in a
403     different way, and has some restrictions. The differences between the
404 nigel 77 two functions are described in the pcrematching documentation.
405    
406 ph10 453 If a data line contains the \D escape sequence, or if the command line
407     contains the -dfa option, the alternative matching function is called.
408 nigel 77 This function finds all possible matches at a given point. If, however,
409 ph10 453 the \F escape sequence is present in the data line, it stops after the
410 nigel 77 first match is found. This is always the shortest possible match.
411    
412    
413     DEFAULT OUTPUT FROM PCRETEST
414    
415 ph10 453 This section describes the output when the normal matching function,
416 nigel 77 pcre_exec(), is being used.
417    
418 nigel 73 When a match succeeds, pcretest outputs the list of captured substrings
419 ph10 453 that pcre_exec() returns, starting with number 0 for the string that
420     matched the whole pattern. Otherwise, it outputs "No match" when the
421     return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
422     tially matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
423     For any other returns, it outputs the PCRE negative error number. Here
424     is an example of an interactive pcretest run.
425 nigel 53
426 nigel 73 $ pcretest
427 nigel 93 PCRE version 7.0 30-Nov-2006
428 nigel 53
429 nigel 73 re> /^abc(\d+)/
430     data> abc123
431     0: abc123
432     1: 123
433     data> xyz
434     No match
435 nigel 53
436 ph10 453 Note that unset capturing substrings that are not followed by one that
437     is set are not returned by pcre_exec(), and are not shown by pcretest.
438     In the following example, there are two capturing substrings, but when
439     the first data line is matched, the second, unset substring is not
440     shown. An "internal" unset substring is shown as "<unset>", as for the
441 ph10 286 second data line.
442    
443     re> /(a)|(b)/
444     data> a
445     0: a
446     1: a
447     data> b
448     0: b
449     1: <unset>
450     2: b
451    
452 ph10 453 If the strings contain any non-printing characters, they are output as
453     \0x escapes, or as \x{...} escapes if the /8 modifier was present on
454     the pattern. See below for the definition of non-printing characters.
455     If the pattern has the /+ modifier, the output for substring 0 is fol-
456     lowed by the the rest of the subject string, identified by "0+" like
457 nigel 93 this:
458 nigel 53
459 nigel 73 re> /cat/+
460     data> cataract
461     0: cat
462     0+ aract
463 nigel 53
464 ph10 453 If the pattern has the /g or /G modifier, the results of successive
465 nigel 73 matching attempts are output in sequence, like this:
466 nigel 53
467 nigel 73 re> /\Bi(\w\w)/g
468     data> Mississippi
469     0: iss
470     1: ss
471     0: iss
472     1: ss
473     0: ipp
474     1: pp
475 nigel 53
476 nigel 73 "No match" is output only if the first match attempt fails.
477 nigel 53
478 ph10 453 If any of the sequences \C, \G, or \L are present in a data line that
479     is successfully matched, the substrings extracted by the convenience
480 nigel 73 functions are output with C, G, or L after the string number instead of
481     a colon. This is in addition to the normal full list. The string length
482 ph10 453 (that is, the return from the extraction function) is given in paren-
483 nigel 73 theses after each string for \C and \G.
484 nigel 53
485 nigel 93 Note that whereas patterns can be continued over several lines (a plain
486 nigel 73 ">" prompt is used for continuations), data lines may not. However new-
487 ph10 453 lines can be included in data by means of the \n escape (or \r, \r\n,
488 nigel 93 etc., depending on the newline sequence setting).
489 nigel 53
490    
491 nigel 77 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
492    
493 ph10 453 When the alternative matching function, pcre_dfa_exec(), is used (by
494     means of the \D escape sequence or the -dfa command line option), the
495     output consists of a list of all the matches that start at the first
496 nigel 77 point in the subject where there is at least one match. For example:
497    
498     re> /(tang|tangerine|tan)/
499     data> yellow tangerine\D
500     0: tangerine
501     1: tang
502     2: tan
503    
504 ph10 453 (Using the normal matching function on this data finds only "tang".)
505     The longest matching string is always given first (and numbered zero).
506 ph10 429 After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
507     lowed by the partially matching substring.
508 nigel 77
509 nigel 93 If /g is present on the pattern, the search for further matches resumes
510     at the end of the longest match. For example:
511 nigel 77
512     re> /(tang|tangerine|tan)/g
513     data> yellow tangerine and tangy sultana\D
514     0: tangerine
515     1: tang
516     2: tan
517     0: tang
518     1: tan
519     0: tan
520    
521 ph10 453 Since the matching function does not support substring capture, the
522     escape sequences that are concerned with captured substrings are not
523 nigel 77 relevant.
524    
525    
526     RESTARTING AFTER A PARTIAL MATCH
527    
528     When the alternative matching function has given the PCRE_ERROR_PARTIAL
529 ph10 453 return, indicating that the subject partially matched the pattern, you
530     can restart the match with additional subject data by means of the \R
531 nigel 77 escape sequence. For example:
532    
533 ph10 155 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
534 nigel 77 data> 23ja\P\D
535     Partial match: 23ja
536     data> n05\R\D
537     0: n05
538    
539 ph10 453 For further information about partial matching, see the pcrepartial
540 nigel 77 documentation.
541    
542    
543 nigel 75 CALLOUTS
544    
545 ph10 453 If the pattern contains any callout requests, pcretest's callout func-
546     tion is called during matching. This works with both matching func-
547 nigel 77 tions. By default, the called function displays the callout number, the
548 ph10 453 start and current positions in the text at the callout time, and the
549 nigel 77 next pattern item to be tested. For example, the output
550 nigel 75
551     --->pqrabcdef
552     0 ^ ^ \d
553    
554 ph10 453 indicates that callout number 0 occurred for a match attempt starting
555     at the fourth character of the subject string, when the pointer was at
556     the seventh character of the data, and when the next pattern item was
557     \d. Just one circumflex is output if the start and current positions
558 nigel 75 are the same.
559    
560     Callouts numbered 255 are assumed to be automatic callouts, inserted as
561 ph10 453 a result of the /C pattern modifier. In this case, instead of showing
562     the callout number, the offset in the pattern, preceded by a plus, is
563 nigel 75 output. For example:
564    
565     re> /\d?[A-E]\*/C
566     data> E*
567     --->E*
568     +0 ^ \d?
569     +3 ^ [A-E]
570     +8 ^^ \*
571     +10 ^ ^
572     0: E*
573    
574 ph10 453 The callout function in pcretest returns zero (carry on matching) by
575     default, but you can use a \C item in a data line (as described above)
576 nigel 75 to change this.
577    
578 ph10 453 Inserting callouts can be helpful when using pcretest to check compli-
579     cated regular expressions. For further information about callouts, see
580 nigel 75 the pcrecallout documentation.
581    
582    
583 nigel 93 NON-PRINTING CHARACTERS
584    
585 ph10 453 When pcretest is outputting text in the compiled version of a pattern,
586     bytes other than 32-126 are always treated as non-printing characters
587 nigel 93 are are therefore shown as hex escapes.
588    
589 ph10 453 When pcretest is outputting text that is a matched part of a subject
590     string, it behaves in the same way, unless a different locale has been
591     set for the pattern (using the /L modifier). In this case, the
592 nigel 93 isprint() function to distinguish printing and non-printing characters.
593    
594    
595 nigel 75 SAVING AND RELOADING COMPILED PATTERNS
596    
597 ph10 453 The facilities described in this section are not available when the
598 nigel 75 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
599     ifier is specified.
600    
601     When the POSIX interface is not in use, you can cause pcretest to write
602 ph10 453 a compiled pattern to a file, by following the modifiers with > and a
603 nigel 75 file name. For example:
604    
605     /pattern/im >/some/file
606    
607 ph10 453 See the pcreprecompile documentation for a discussion about saving and
608 nigel 75 re-using compiled patterns.
609    
610 ph10 453 The data that is written is binary. The first eight bytes are the
611     length of the compiled pattern data followed by the length of the
612     optional study data, each written as four bytes in big-endian order
613     (most significant byte first). If there is no study data (either the
614 nigel 75 pattern was not studied, or studying did not return any data), the sec-
615 ph10 453 ond length is zero. The lengths are followed by an exact copy of the
616 nigel 75 compiled pattern. If there is additional study data, this follows imme-
617 ph10 453 diately after the compiled pattern. After writing the file, pcretest
618 nigel 75 expects to read a new pattern.
619    
620     A saved pattern can be reloaded into pcretest by specifing < and a file
621 ph10 453 name instead of a pattern. The name of the file must not contain a <
622     character, as otherwise pcretest will interpret the line as a pattern
623 nigel 75 delimited by < characters. For example:
624    
625     re> </some/file
626     Compiled regex loaded from /some/file
627     No study data
628    
629 ph10 453 When the pattern has been loaded, pcretest proceeds to read data lines
630 nigel 75 in the usual way.
631    
632 ph10 453 You can copy a file written by pcretest to a different host and reload
633     it there, even if the new host has opposite endianness to the one on
634     which the pattern was compiled. For example, you can compile on an i86
635 nigel 75 machine and run on a SPARC machine.
636    
637 ph10 453 File names for saving and reloading can be absolute or relative, but
638     note that the shell facility of expanding a file name that starts with
639 nigel 75 a tilde (~) is not available.
640    
641 ph10 453 The ability to save and reload files in pcretest is intended for test-
642     ing and experimentation. It is not intended for production use because
643     only a single pattern can be written to a file. Furthermore, there is
644     no facility for supplying custom character tables for use with a
645     reloaded pattern. If the original pattern was compiled with custom
646     tables, an attempt to match a subject string using a reloaded pattern
647     is likely to cause pcretest to crash. Finally, if you attempt to load
648 nigel 75 a file that is not in the correct format, the result is undefined.
649    
650    
651 nigel 93 SEE ALSO
652    
653 ph10 453 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
654 nigel 93 pcrepattern(3), pcreprecompile(3).
655    
656    
657 nigel 63 AUTHOR
658 nigel 53
659 nigel 77 Philip Hazel
660 ph10 99 University Computing Service
661 nigel 93 Cambridge CB2 3QH, England.
662 nigel 53
663 ph10 99
664     REVISION
665    
666 ph10 461 Last updated: 26 September 2009
667 ph10 392 Copyright (c) 1997-2009 University of Cambridge.

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