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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     string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
200     flags set in order to search for another, non-empty, match at the same
201     point. If this second match fails, the start offset is advanced by
202     one, and the normal match is retried. This imitates the way Perl han-
203 nigel 73 dles such cases when using the /g modifier or the split() function.
204 nigel 49
205 nigel 91 Other modifiers
206    
207 nigel 75 There are yet more modifiers for controlling the way pcretest operates.
208 nigel 49
209 nigel 87 The /+ modifier requests that as well as outputting the substring that
210     matched the entire pattern, pcretest should in addition output the
211     remainder of the subject string. This is useful for tests where the
212 nigel 73 subject contains multiple copies of the same substring.
213 nigel 41
214 nigel 93 The /B modifier is a debugging feature. It requests that pcretest out-
215 ph10 123 put a representation of the compiled byte code after compilation. Nor-
216     mally this information contains length and offset values; however, if
217     /Z is also present, this data is replaced by spaces. This is a special
218     feature for use in the automatic test scripts; it ensures that the same
219     output is generated for different internal link sizes.
220 nigel 93
221     The /L modifier must be followed directly by the name of a locale, for
222 nigel 73 example,
223 nigel 41
224 nigel 75 /pattern/Lfr_FR
225 nigel 41
226 nigel 75 For this reason, it must be the last modifier. The given locale is set,
227 nigel 93 pcre_maketables() is called to build a set of character tables for the
228     locale, and this is then passed to pcre_compile() when compiling the
229     regular expression. Without an /L modifier, NULL is passed as the
230     tables pointer; that is, /L applies only to the expression on which it
231 nigel 75 appears.
232 nigel 41
233 nigel 93 The /I modifier requests that pcretest output information about the
234     compiled pattern (whether it is anchored, has a fixed first character,
235     and so on). It does this by calling pcre_fullinfo() after compiling a
236     pattern. If the pattern is studied, the results of that are also out-
237 nigel 75 put.
238 nigel 63
239 nigel 93 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
240     that is, both the /B and the /I modifiers.
241 nigel 41
242 nigel 75 The /F modifier causes pcretest to flip the byte order of the fields in
243 nigel 93 the compiled pattern that contain 2-byte and 4-byte numbers. This
244     facility is for testing the feature in PCRE that allows it to execute
245 nigel 75 patterns that were compiled on a host with a different endianness. This
246 nigel 93 feature is not available when the POSIX interface to PCRE is being
247     used, that is, when the /P pattern modifier is specified. See also the
248 nigel 75 section about saving and reloading compiled patterns below.
249    
250 nigel 93 The /S modifier causes pcre_study() to be called after the expression
251 nigel 73 has been compiled, and the results used when the expression is matched.
252 nigel 41
253 ph10 392 The /M modifier causes the size of memory block used to hold the com-
254 nigel 73 piled pattern to be output.
255 nigel 41
256 ph10 392 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
257     rather than its native API. When this is done, all other modifiers
258     except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
259     and REG_NEWLINE is set if /m is present. The wrapper functions force
260     PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
261 nigel 41
262 nigel 93 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
263     set. This turns on support for UTF-8 character handling in PCRE, pro-
264     vided that it was compiled with this support enabled. This modifier
265 nigel 73 also causes any non-printing characters in output strings to be printed
266     using the \x{hh...} notation if they are valid UTF-8 sequences.
267 nigel 41
268 nigel 93 If the /? modifier is used with /8, it causes pcretest to call
269     pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
270 nigel 73 checking of the string for UTF-8 validity.
271 nigel 41
272 nigel 71
273 nigel 53 DATA LINES
274 nigel 63
275 nigel 93 Before each data line is passed to pcre_exec(), leading and trailing
276     whitespace is removed, and it is then scanned for \ escapes. Some of
277     these are pretty esoteric features, intended for checking out some of
278     the more complicated features of PCRE. If you are just testing "ordi-
279     nary" regular expressions, you probably don't need any of these. The
280 nigel 73 following escapes are recognized:
281 nigel 49
282 nigel 93 \a alarm (BEL, \x07)
283     \b backspace (\x08)
284     \e escape (\x27)
285     \f formfeed (\x0c)
286     \n newline (\x0a)
287 nigel 91 \qdd set the PCRE_MATCH_LIMIT limit to dd
288     (any number of digits)
289 nigel 93 \r carriage return (\x0d)
290     \t tab (\x09)
291     \v vertical tab (\x0b)
292 nigel 73 \nnn octal character (up to 3 octal digits)
293     \xhh hexadecimal character (up to 2 hex digits)
294     \x{hh...} hexadecimal character, any number of digits
295     in UTF-8 mode
296     \A pass the PCRE_ANCHORED option to pcre_exec()
297 nigel 91 or pcre_dfa_exec()
298 nigel 73 \B pass the PCRE_NOTBOL option to pcre_exec()
299 nigel 91 or pcre_dfa_exec()
300 nigel 73 \Cdd call pcre_copy_substring() for substring dd
301 nigel 75 after a successful match (number less than 32)
302 nigel 73 \Cname call pcre_copy_named_substring() for substring
303     "name" after a successful match (name termin-
304     ated by next non alphanumeric character)
305     \C+ show the current captured substrings at callout
306     time
307     \C- do not supply a callout function
308     \C!n return 1 instead of 0 when callout number n is
309     reached
310     \C!n!m return 1 instead of 0 when callout number n is
311     reached for the nth time
312     \C*n pass the number n (may be negative) as callout
313 nigel 75 data; this is used as the callout return value
314 nigel 77 \D use the pcre_dfa_exec() match function
315     \F only shortest match for pcre_dfa_exec()
316 nigel 73 \Gdd call pcre_get_substring() for substring dd
317 nigel 75 after a successful match (number less than 32)
318 nigel 73 \Gname call pcre_get_named_substring() for substring
319     "name" after a successful match (name termin-
320     ated by next non-alphanumeric character)
321     \L call pcre_get_substringlist() after a
322     successful match
323 nigel 87 \M discover the minimum MATCH_LIMIT and
324     MATCH_LIMIT_RECURSION settings
325 nigel 73 \N pass the PCRE_NOTEMPTY option to pcre_exec()
326 nigel 91 or pcre_dfa_exec()
327 nigel 73 \Odd set the size of the output vector passed to
328 nigel 75 pcre_exec() to dd (any number of digits)
329     \P pass the PCRE_PARTIAL option to pcre_exec()
330 nigel 77 or pcre_dfa_exec()
331 nigel 91 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
332     (any number of digits)
333 nigel 77 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
334 nigel 73 \S output details of memory get/free calls during matching
335     \Z pass the PCRE_NOTEOL option to pcre_exec()
336 nigel 91 or pcre_dfa_exec()
337 nigel 73 \? pass the PCRE_NO_UTF8_CHECK option to
338 nigel 91 pcre_exec() or pcre_dfa_exec()
339 nigel 75 \>dd start the match at offset dd (any number of digits);
340     this sets the startoffset argument for pcre_exec()
341 nigel 91 or pcre_dfa_exec()
342     \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
343     or pcre_dfa_exec()
344     \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
345     or pcre_dfa_exec()
346     \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
347     or pcre_dfa_exec()
348 ph10 150 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
349     or pcre_dfa_exec()
350 nigel 93 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
351     or pcre_dfa_exec()
352 nigel 71
353 nigel 93 The escapes that specify line ending sequences are literal strings,
354     exactly as shown. No more than one newline setting should be present in
355     any data line.
356 nigel 75
357 nigel 93 A backslash followed by anything else just escapes the anything else.
358     If the very last character is a backslash, it is ignored. This gives a
359     way of passing an empty line as data, since a real empty line termi-
360     nates the data input.
361    
362 nigel 91 If \M is present, pcretest calls pcre_exec() several times, with dif-
363     ferent values in the match_limit and match_limit_recursion fields of
364     the pcre_extra data structure, until it finds the minimum numbers for
365 nigel 87 each parameter that allow pcre_exec() to complete. The match_limit num-
366 nigel 91 ber is a measure of the amount of backtracking that takes place, and
367 nigel 87 checking it out can be instructive. For most simple matches, the number
368 nigel 91 is quite small, but for patterns with very large numbers of matching
369     possibilities, it can become large very quickly with increasing length
370 nigel 87 of subject string. The match_limit_recursion number is a measure of how
371 nigel 91 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
372 nigel 87 memory is needed to complete the match attempt.
373 nigel 41
374 nigel 91 When \O is used, the value specified may be higher or lower than the
375 nigel 75 size set by the -O command line option (or defaulted to 45); \O applies
376     only to the call of pcre_exec() for the line in which it appears.
377 nigel 63
378 nigel 91 If the /P modifier was present on the pattern, causing the POSIX wrap-
379     per API to be used, the only option-setting sequences that have any
380     effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
381 nigel 87 to be passed to regexec().
382 nigel 41
383 nigel 91 The use of \x{hh...} to represent UTF-8 characters is not dependent on
384     the use of the /8 modifier on the pattern. It is recognized always.
385     There may be any number of hexadecimal digits inside the braces. The
386 ph10 211 result is from one to six bytes, encoded according to the original
387     UTF-8 rules of RFC 2279. This allows for values in the range 0 to
388     0x7FFFFFFF. Note that not all of those are valid Unicode code points,
389     or indeed valid UTF-8 characters according to the later rules in RFC
390     3629.
391 nigel 41
392 nigel 53
393 nigel 77 THE ALTERNATIVE MATCHING FUNCTION
394 nigel 53
395 ph10 211 By default, pcretest uses the standard PCRE matching function,
396 nigel 77 pcre_exec() to match each data line. From release 6.0, PCRE supports an
397 ph10 211 alternative matching function, pcre_dfa_test(), which operates in a
398     different way, and has some restrictions. The differences between the
399 nigel 77 two functions are described in the pcrematching documentation.
400    
401 ph10 211 If a data line contains the \D escape sequence, or if the command line
402     contains the -dfa option, the alternative matching function is called.
403 nigel 77 This function finds all possible matches at a given point. If, however,
404 ph10 211 the \F escape sequence is present in the data line, it stops after the
405 nigel 77 first match is found. This is always the shortest possible match.
406    
407    
408     DEFAULT OUTPUT FROM PCRETEST
409    
410 ph10 211 This section describes the output when the normal matching function,
411 nigel 77 pcre_exec(), is being used.
412    
413 nigel 73 When a match succeeds, pcretest outputs the list of captured substrings
414 ph10 211 that pcre_exec() returns, starting with number 0 for the string that
415 nigel 75 matched the whole pattern. Otherwise, it outputs "No match" or "Partial
416 ph10 211 match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
417     TIAL, respectively, and otherwise the PCRE negative error number. Here
418 nigel 75 is an example of an interactive pcretest run.
419 nigel 53
420 nigel 73 $ pcretest
421 nigel 93 PCRE version 7.0 30-Nov-2006
422 nigel 53
423 nigel 73 re> /^abc(\d+)/
424     data> abc123
425     0: abc123
426     1: 123
427     data> xyz
428     No match
429 nigel 53
430 ph10 286 Note that unset capturing substrings that are not followed by one that
431     is set are not returned by pcre_exec(), and are not shown by pcretest.
432     In the following example, there are two capturing substrings, but when
433     the first data line is matched, the second, unset substring is not
434     shown. An "internal" unset substring is shown as "<unset>", as for the
435     second data line.
436    
437     re> /(a)|(b)/
438     data> a
439     0: a
440     1: a
441     data> b
442     0: b
443     1: <unset>
444     2: b
445    
446     If the strings contain any non-printing characters, they are output as
447     \0x escapes, or as \x{...} escapes if the /8 modifier was present on
448     the pattern. See below for the definition of non-printing characters.
449     If the pattern has the /+ modifier, the output for substring 0 is fol-
450     lowed by the the rest of the subject string, identified by "0+" like
451 nigel 93 this:
452 nigel 53
453 nigel 73 re> /cat/+
454     data> cataract
455     0: cat
456     0+ aract
457 nigel 53
458 ph10 286 If the pattern has the /g or /G modifier, the results of successive
459 nigel 73 matching attempts are output in sequence, like this:
460 nigel 53
461 nigel 73 re> /\Bi(\w\w)/g
462     data> Mississippi
463     0: iss
464     1: ss
465     0: iss
466     1: ss
467     0: ipp
468     1: pp
469 nigel 53
470 nigel 73 "No match" is output only if the first match attempt fails.
471 nigel 53
472 ph10 286 If any of the sequences \C, \G, or \L are present in a data line that
473     is successfully matched, the substrings extracted by the convenience
474 nigel 73 functions are output with C, G, or L after the string number instead of
475     a colon. This is in addition to the normal full list. The string length
476 ph10 286 (that is, the return from the extraction function) is given in paren-
477 nigel 73 theses after each string for \C and \G.
478 nigel 53
479 nigel 93 Note that whereas patterns can be continued over several lines (a plain
480 nigel 73 ">" prompt is used for continuations), data lines may not. However new-
481 ph10 286 lines can be included in data by means of the \n escape (or \r, \r\n,
482 nigel 93 etc., depending on the newline sequence setting).
483 nigel 53
484    
485 nigel 77 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
486    
487 ph10 286 When the alternative matching function, pcre_dfa_exec(), is used (by
488     means of the \D escape sequence or the -dfa command line option), the
489     output consists of a list of all the matches that start at the first
490 nigel 77 point in the subject where there is at least one match. For example:
491    
492     re> /(tang|tangerine|tan)/
493     data> yellow tangerine\D
494     0: tangerine
495     1: tang
496     2: tan
497    
498 ph10 286 (Using the normal matching function on this data finds only "tang".)
499 ph10 392 The longest matching string is always given first (and numbered zero).
500 nigel 77
501 nigel 93 If /g is present on the pattern, the search for further matches resumes
502     at the end of the longest match. For example:
503 nigel 77
504     re> /(tang|tangerine|tan)/g
505     data> yellow tangerine and tangy sultana\D
506     0: tangerine
507     1: tang
508     2: tan
509     0: tang
510     1: tan
511     0: tan
512    
513 ph10 392 Since the matching function does not support substring capture, the
514     escape sequences that are concerned with captured substrings are not
515 nigel 77 relevant.
516    
517    
518     RESTARTING AFTER A PARTIAL MATCH
519    
520     When the alternative matching function has given the PCRE_ERROR_PARTIAL
521 ph10 392 return, indicating that the subject partially matched the pattern, you
522     can restart the match with additional subject data by means of the \R
523 nigel 77 escape sequence. For example:
524    
525 ph10 155 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
526 nigel 77 data> 23ja\P\D
527     Partial match: 23ja
528     data> n05\R\D
529     0: n05
530    
531 ph10 392 For further information about partial matching, see the pcrepartial
532 nigel 77 documentation.
533    
534    
535 nigel 75 CALLOUTS
536    
537 ph10 392 If the pattern contains any callout requests, pcretest's callout func-
538     tion is called during matching. This works with both matching func-
539 nigel 77 tions. By default, the called function displays the callout number, the
540 ph10 392 start and current positions in the text at the callout time, and the
541 nigel 77 next pattern item to be tested. For example, the output
542 nigel 75
543     --->pqrabcdef
544     0 ^ ^ \d
545    
546 ph10 392 indicates that callout number 0 occurred for a match attempt starting
547     at the fourth character of the subject string, when the pointer was at
548     the seventh character of the data, and when the next pattern item was
549     \d. Just one circumflex is output if the start and current positions
550 nigel 75 are the same.
551    
552     Callouts numbered 255 are assumed to be automatic callouts, inserted as
553 ph10 392 a result of the /C pattern modifier. In this case, instead of showing
554     the callout number, the offset in the pattern, preceded by a plus, is
555 nigel 75 output. For example:
556    
557     re> /\d?[A-E]\*/C
558     data> E*
559     --->E*
560     +0 ^ \d?
561     +3 ^ [A-E]
562     +8 ^^ \*
563     +10 ^ ^
564     0: E*
565    
566 ph10 392 The callout function in pcretest returns zero (carry on matching) by
567     default, but you can use a \C item in a data line (as described above)
568 nigel 75 to change this.
569    
570 ph10 392 Inserting callouts can be helpful when using pcretest to check compli-
571     cated regular expressions. For further information about callouts, see
572 nigel 75 the pcrecallout documentation.
573    
574    
575 nigel 93 NON-PRINTING CHARACTERS
576    
577 ph10 392 When pcretest is outputting text in the compiled version of a pattern,
578     bytes other than 32-126 are always treated as non-printing characters
579 nigel 93 are are therefore shown as hex escapes.
580    
581 ph10 392 When pcretest is outputting text that is a matched part of a subject
582     string, it behaves in the same way, unless a different locale has been
583     set for the pattern (using the /L modifier). In this case, the
584 nigel 93 isprint() function to distinguish printing and non-printing characters.
585    
586    
587 nigel 75 SAVING AND RELOADING COMPILED PATTERNS
588    
589 ph10 286 The facilities described in this section are not available when the
590 nigel 75 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
591     ifier is specified.
592    
593     When the POSIX interface is not in use, you can cause pcretest to write
594 ph10 286 a compiled pattern to a file, by following the modifiers with > and a
595 nigel 75 file name. For example:
596    
597     /pattern/im >/some/file
598    
599 ph10 286 See the pcreprecompile documentation for a discussion about saving and
600 nigel 75 re-using compiled patterns.
601    
602 ph10 286 The data that is written is binary. The first eight bytes are the
603     length of the compiled pattern data followed by the length of the
604     optional study data, each written as four bytes in big-endian order
605     (most significant byte first). If there is no study data (either the
606 nigel 75 pattern was not studied, or studying did not return any data), the sec-
607 ph10 286 ond length is zero. The lengths are followed by an exact copy of the
608 nigel 75 compiled pattern. If there is additional study data, this follows imme-
609 ph10 286 diately after the compiled pattern. After writing the file, pcretest
610 nigel 75 expects to read a new pattern.
611    
612     A saved pattern can be reloaded into pcretest by specifing < and a file
613 ph10 286 name instead of a pattern. The name of the file must not contain a <
614     character, as otherwise pcretest will interpret the line as a pattern
615 nigel 75 delimited by < characters. For example:
616    
617     re> </some/file
618     Compiled regex loaded from /some/file
619     No study data
620    
621 ph10 286 When the pattern has been loaded, pcretest proceeds to read data lines
622 nigel 75 in the usual way.
623    
624 ph10 286 You can copy a file written by pcretest to a different host and reload
625     it there, even if the new host has opposite endianness to the one on
626     which the pattern was compiled. For example, you can compile on an i86
627 nigel 75 machine and run on a SPARC machine.
628    
629 ph10 286 File names for saving and reloading can be absolute or relative, but
630     note that the shell facility of expanding a file name that starts with
631 nigel 75 a tilde (~) is not available.
632    
633 ph10 286 The ability to save and reload files in pcretest is intended for test-
634     ing and experimentation. It is not intended for production use because
635     only a single pattern can be written to a file. Furthermore, there is
636     no facility for supplying custom character tables for use with a
637     reloaded pattern. If the original pattern was compiled with custom
638     tables, an attempt to match a subject string using a reloaded pattern
639     is likely to cause pcretest to crash. Finally, if you attempt to load
640 nigel 75 a file that is not in the correct format, the result is undefined.
641    
642    
643 nigel 93 SEE ALSO
644    
645 ph10 286 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
646 nigel 93 pcrepattern(3), pcreprecompile(3).
647    
648    
649 nigel 63 AUTHOR
650 nigel 53
651 nigel 77 Philip Hazel
652 ph10 99 University Computing Service
653 nigel 93 Cambridge CB2 3QH, England.
654 nigel 53
655 ph10 99
656     REVISION
657    
658 ph10 392 Last updated: 10 March 2009
659     Copyright (c) 1997-2009 University of Cambridge.

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