/[pcre]/code/trunk/doc/pcretest.txt
ViewVC logotype

Contents of /code/trunk/doc/pcretest.txt

Parent Directory Parent Directory | Revision Log Revision Log


Revision 518 - (hide annotations) (download)
Tue May 18 15:47:01 2010 UTC (3 years ago) by ph10
File MIME type: text/plain
File size: 31915 byte(s)
Added PCRE_UCP and related stuff to make \w etc use Unicode properties.

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 518 /8 PCRE_UTF8
161     /? PCRE_NO_UTF8_CHECK
162 ph10 231 /A PCRE_ANCHORED
163     /C PCRE_AUTO_CALLOUT
164     /E PCRE_DOLLAR_ENDONLY
165     /f PCRE_FIRSTLINE
166     /J PCRE_DUPNAMES
167     /N PCRE_NO_AUTO_CAPTURE
168     /U PCRE_UNGREEDY
169 ph10 518 /W PCRE_UCP
170 ph10 231 /X PCRE_EXTRA
171 ph10 345 /<JS> PCRE_JAVASCRIPT_COMPAT
172 ph10 231 /<cr> PCRE_NEWLINE_CR
173     /<lf> PCRE_NEWLINE_LF
174     /<crlf> PCRE_NEWLINE_CRLF
175     /<anycrlf> PCRE_NEWLINE_ANYCRLF
176     /<any> PCRE_NEWLINE_ANY
177     /<bsr_anycrlf> PCRE_BSR_ANYCRLF
178     /<bsr_unicode> PCRE_BSR_UNICODE
179 nigel 75
180 ph10 518 The modifiers that are enclosed in angle brackets are literal strings
181     as shown, including the angle brackets, but the letters can be in
182     either case. This example sets multiline matching with CRLF as the line
183     ending sequence:
184 nigel 91
185 nigel 93 /^abc/m<crlf>
186    
187 ph10 518 As well as turning on the PCRE_UTF8 option, the /8 modifier also causes
188     any non-printing characters in output strings to be printed using the
189     \x{hh...} notation if they are valid UTF-8 sequences. Full details of
190     the PCRE options are given in the pcreapi documentation.
191 nigel 93
192 nigel 91 Finding all matches in a string
193    
194 ph10 518 Searching for all possible matches within each subject string can be
195     requested by the /g or /G modifier. After finding a match, PCRE is
196 nigel 73 called again to search the remainder of the subject string. The differ-
197     ence between /g and /G is that the former uses the startoffset argument
198 ph10 518 to pcre_exec() to start searching at a new point within the entire
199     string (which is in effect what Perl does), whereas the latter passes
200     over a shortened substring. This makes a difference to the matching
201 nigel 73 process if the pattern begins with a lookbehind assertion (including \b
202     or \B).
203 nigel 49
204 ph10 518 If any call to pcre_exec() in a /g or /G sequence matches an empty
205     string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
206     PCRE_ANCHORED flags set in order to search for another, non-empty,
207     match at the same point. If this second match fails, the start offset
208     is advanced by one character, and the normal match is retried. This
209     imitates the way Perl handles such cases when using the /g modifier or
210 ph10 453 the split() function.
211 nigel 49
212 nigel 91 Other modifiers
213    
214 nigel 75 There are yet more modifiers for controlling the way pcretest operates.
215 nigel 49
216 ph10 518 The /+ modifier requests that as well as outputting the substring that
217     matched the entire pattern, pcretest should in addition output the
218     remainder of the subject string. This is useful for tests where the
219 nigel 73 subject contains multiple copies of the same substring.
220 nigel 41
221 ph10 518 The /B modifier is a debugging feature. It requests that pcretest out-
222     put a representation of the compiled byte code after compilation. Nor-
223     mally this information contains length and offset values; however, if
224     /Z is also present, this data is replaced by spaces. This is a special
225 ph10 123 feature for use in the automatic test scripts; it ensures that the same
226     output is generated for different internal link sizes.
227 nigel 93
228 ph10 518 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
229 nigel 93 that is, both the /B and the /I modifiers.
230 nigel 41
231 nigel 75 The /F modifier causes pcretest to flip the byte order of the fields in
232 ph10 518 the compiled pattern that contain 2-byte and 4-byte numbers. This
233     facility is for testing the feature in PCRE that allows it to execute
234 nigel 75 patterns that were compiled on a host with a different endianness. This
235 ph10 518 feature is not available when the POSIX interface to PCRE is being
236     used, that is, when the /P pattern modifier is specified. See also the
237 nigel 75 section about saving and reloading compiled patterns below.
238    
239 ph10 518 The /I modifier requests that pcretest output information about the
240     compiled pattern (whether it is anchored, has a fixed first character,
241     and so on). It does this by calling pcre_fullinfo() after compiling a
242     pattern. If the pattern is studied, the results of that are also out-
243 ph10 512 put.
244 nigel 41
245 ph10 518 The /K modifier requests pcretest to show names from backtracking con-
246     trol verbs that are returned from calls to pcre_exec(). It causes
247     pcretest to create a pcre_extra block if one has not already been cre-
248 ph10 512 ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
249     the mark field within it, every time that pcre_exec() is called. If the
250 ph10 518 variable that the mark field points to is non-NULL for a match, non-
251 ph10 512 match, or partial match, pcretest prints the string to which it points.
252     For a match, this is shown on a line by itself, tagged with "MK:". For
253     a non-match it is added to the message.
254    
255 ph10 518 The /L modifier must be followed directly by the name of a locale, for
256 ph10 512 example,
257    
258     /pattern/Lfr_FR
259    
260     For this reason, it must be the last modifier. The given locale is set,
261 ph10 518 pcre_maketables() is called to build a set of character tables for the
262     locale, and this is then passed to pcre_compile() when compiling the
263     regular expression. Without an /L modifier, NULL is passed as the
264     tables pointer; that is, /L applies only to the expression on which it
265 ph10 512 appears.
266    
267 ph10 518 The /M modifier causes the size of memory block used to hold the com-
268 nigel 73 piled pattern to be output.
269 nigel 41
270 ph10 518 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
271     rather than its native API. When this is done, all other modifiers
272     except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
273     and REG_NEWLINE is set if /m is present. The wrapper functions force
274 ph10 392 PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
275 nigel 41
276 ph10 518 The /S modifier causes pcre_study() to be called after the expression
277 ph10 512 has been compiled, and the results used when the expression is matched.
278 nigel 41
279    
280 nigel 53 DATA LINES
281 nigel 63
282 ph10 518 Before each data line is passed to pcre_exec(), leading and trailing
283     whitespace is removed, and it is then scanned for \ escapes. Some of
284     these are pretty esoteric features, intended for checking out some of
285     the more complicated features of PCRE. If you are just testing "ordi-
286     nary" regular expressions, you probably don't need any of these. The
287 nigel 73 following escapes are recognized:
288 nigel 49
289 nigel 93 \a alarm (BEL, \x07)
290     \b backspace (\x08)
291     \e escape (\x27)
292     \f formfeed (\x0c)
293     \n newline (\x0a)
294 nigel 91 \qdd set the PCRE_MATCH_LIMIT limit to dd
295     (any number of digits)
296 nigel 93 \r carriage return (\x0d)
297     \t tab (\x09)
298     \v vertical tab (\x0b)
299 nigel 73 \nnn octal character (up to 3 octal digits)
300     \xhh hexadecimal character (up to 2 hex digits)
301     \x{hh...} hexadecimal character, any number of digits
302     in UTF-8 mode
303     \A pass the PCRE_ANCHORED option to pcre_exec()
304 nigel 91 or pcre_dfa_exec()
305 nigel 73 \B pass the PCRE_NOTBOL option to pcre_exec()
306 nigel 91 or pcre_dfa_exec()
307 nigel 73 \Cdd call pcre_copy_substring() for substring dd
308 nigel 75 after a successful match (number less than 32)
309 nigel 73 \Cname call pcre_copy_named_substring() for substring
310     "name" after a successful match (name termin-
311     ated by next non alphanumeric character)
312     \C+ show the current captured substrings at callout
313     time
314     \C- do not supply a callout function
315     \C!n return 1 instead of 0 when callout number n is
316     reached
317     \C!n!m return 1 instead of 0 when callout number n is
318     reached for the nth time
319     \C*n pass the number n (may be negative) as callout
320 nigel 75 data; this is used as the callout return value
321 nigel 77 \D use the pcre_dfa_exec() match function
322     \F only shortest match for pcre_dfa_exec()
323 nigel 73 \Gdd call pcre_get_substring() for substring dd
324 nigel 75 after a successful match (number less than 32)
325 nigel 73 \Gname call pcre_get_named_substring() for substring
326     "name" after a successful match (name termin-
327     ated by next non-alphanumeric character)
328     \L call pcre_get_substringlist() after a
329     successful match
330 nigel 87 \M discover the minimum MATCH_LIMIT and
331     MATCH_LIMIT_RECURSION settings
332 nigel 73 \N pass the PCRE_NOTEMPTY option to pcre_exec()
333 ph10 453 or pcre_dfa_exec(); if used twice, pass the
334     PCRE_NOTEMPTY_ATSTART option
335 nigel 73 \Odd set the size of the output vector passed to
336 nigel 75 pcre_exec() to dd (any number of digits)
337 ph10 429 \P pass the PCRE_PARTIAL_SOFT option to pcre_exec()
338     or pcre_dfa_exec(); if used twice, pass the
339     PCRE_PARTIAL_HARD option
340 nigel 91 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
341     (any number of digits)
342 nigel 77 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
343 nigel 73 \S output details of memory get/free calls during matching
344 ph10 461 \Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
345     or pcre_dfa_exec()
346 nigel 73 \Z pass the PCRE_NOTEOL option to pcre_exec()
347 nigel 91 or pcre_dfa_exec()
348 nigel 73 \? pass the PCRE_NO_UTF8_CHECK option to
349 nigel 91 pcre_exec() or pcre_dfa_exec()
350 nigel 75 \>dd start the match at offset dd (any number of digits);
351     this sets the startoffset argument for pcre_exec()
352 nigel 91 or pcre_dfa_exec()
353     \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
354     or pcre_dfa_exec()
355     \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
356     or pcre_dfa_exec()
357     \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
358     or pcre_dfa_exec()
359 ph10 150 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
360     or pcre_dfa_exec()
361 nigel 93 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
362     or pcre_dfa_exec()
363 nigel 71
364 ph10 518 The escapes that specify line ending sequences are literal strings,
365 nigel 93 exactly as shown. No more than one newline setting should be present in
366     any data line.
367 nigel 75
368 ph10 518 A backslash followed by anything else just escapes the anything else.
369     If the very last character is a backslash, it is ignored. This gives a
370     way of passing an empty line as data, since a real empty line termi-
371 nigel 93 nates the data input.
372    
373 ph10 518 If \M is present, pcretest calls pcre_exec() several times, with dif-
374     ferent values in the match_limit and match_limit_recursion fields of
375     the pcre_extra data structure, until it finds the minimum numbers for
376 nigel 87 each parameter that allow pcre_exec() to complete. The match_limit num-
377 ph10 518 ber is a measure of the amount of backtracking that takes place, and
378 nigel 87 checking it out can be instructive. For most simple matches, the number
379 ph10 518 is quite small, but for patterns with very large numbers of matching
380     possibilities, it can become large very quickly with increasing length
381 nigel 87 of subject string. The match_limit_recursion number is a measure of how
382 ph10 518 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
383 nigel 87 memory is needed to complete the match attempt.
384 nigel 41
385 ph10 518 When \O is used, the value specified may be higher or lower than the
386 nigel 75 size set by the -O command line option (or defaulted to 45); \O applies
387     only to the call of pcre_exec() for the line in which it appears.
388 nigel 63
389 ph10 518 If the /P modifier was present on the pattern, causing the POSIX wrap-
390     per API to be used, the only option-setting sequences that have any
391     effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
392 nigel 87 to be passed to regexec().
393 nigel 41
394 ph10 518 The use of \x{hh...} to represent UTF-8 characters is not dependent on
395     the use of the /8 modifier on the pattern. It is recognized always.
396     There may be any number of hexadecimal digits inside the braces. The
397     result is from one to six bytes, encoded according to the original
398     UTF-8 rules of RFC 2279. This allows for values in the range 0 to
399     0x7FFFFFFF. Note that not all of those are valid Unicode code points,
400     or indeed valid UTF-8 characters according to the later rules in RFC
401 ph10 211 3629.
402 nigel 41
403 nigel 53
404 nigel 77 THE ALTERNATIVE MATCHING FUNCTION
405 nigel 53
406 ph10 518 By default, pcretest uses the standard PCRE matching function,
407 nigel 77 pcre_exec() to match each data line. From release 6.0, PCRE supports an
408 ph10 518 alternative matching function, pcre_dfa_test(), which operates in a
409     different way, and has some restrictions. The differences between the
410 nigel 77 two functions are described in the pcrematching documentation.
411    
412 ph10 518 If a data line contains the \D escape sequence, or if the command line
413     contains the -dfa option, the alternative matching function is called.
414 nigel 77 This function finds all possible matches at a given point. If, however,
415 ph10 518 the \F escape sequence is present in the data line, it stops after the
416 nigel 77 first match is found. This is always the shortest possible match.
417    
418    
419     DEFAULT OUTPUT FROM PCRETEST
420    
421 ph10 518 This section describes the output when the normal matching function,
422 nigel 77 pcre_exec(), is being used.
423    
424 nigel 73 When a match succeeds, pcretest outputs the list of captured substrings
425 ph10 518 that pcre_exec() returns, starting with number 0 for the string that
426     matched the whole pattern. Otherwise, it outputs "No match" when the
427 ph10 453 return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
428 ph10 518 tially matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
429     For any other returns, it outputs the PCRE negative error number. Here
430 ph10 453 is an example of an interactive pcretest run.
431 nigel 53
432 nigel 73 $ pcretest
433 nigel 93 PCRE version 7.0 30-Nov-2006
434 nigel 53
435 nigel 73 re> /^abc(\d+)/
436     data> abc123
437     0: abc123
438     1: 123
439     data> xyz
440     No match
441 nigel 53
442 ph10 518 Note that unset capturing substrings that are not followed by one that
443     is set are not returned by pcre_exec(), and are not shown by pcretest.
444     In the following example, there are two capturing substrings, but when
445     the first data line is matched, the second, unset substring is not
446     shown. An "internal" unset substring is shown as "<unset>", as for the
447 ph10 286 second data line.
448    
449     re> /(a)|(b)/
450     data> a
451     0: a
452     1: a
453     data> b
454     0: b
455     1: <unset>
456     2: b
457    
458 ph10 518 If the strings contain any non-printing characters, they are output as
459     \0x escapes, or as \x{...} escapes if the /8 modifier was present on
460     the pattern. See below for the definition of non-printing characters.
461     If the pattern has the /+ modifier, the output for substring 0 is fol-
462     lowed by the the rest of the subject string, identified by "0+" like
463 nigel 93 this:
464 nigel 53
465 nigel 73 re> /cat/+
466     data> cataract
467     0: cat
468     0+ aract
469 nigel 53
470 ph10 518 If the pattern has the /g or /G modifier, the results of successive
471 nigel 73 matching attempts are output in sequence, like this:
472 nigel 53
473 nigel 73 re> /\Bi(\w\w)/g
474     data> Mississippi
475     0: iss
476     1: ss
477     0: iss
478     1: ss
479     0: ipp
480     1: pp
481 nigel 53
482 nigel 73 "No match" is output only if the first match attempt fails.
483 nigel 53
484 ph10 518 If any of the sequences \C, \G, or \L are present in a data line that
485     is successfully matched, the substrings extracted by the convenience
486 nigel 73 functions are output with C, G, or L after the string number instead of
487     a colon. This is in addition to the normal full list. The string length
488 ph10 518 (that is, the return from the extraction function) is given in paren-
489 nigel 73 theses after each string for \C and \G.
490 nigel 53
491 nigel 93 Note that whereas patterns can be continued over several lines (a plain
492 nigel 73 ">" prompt is used for continuations), data lines may not. However new-
493 ph10 518 lines can be included in data by means of the \n escape (or \r, \r\n,
494 nigel 93 etc., depending on the newline sequence setting).
495 nigel 53
496    
497 nigel 77 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
498    
499 ph10 518 When the alternative matching function, pcre_dfa_exec(), is used (by
500     means of the \D escape sequence or the -dfa command line option), the
501     output consists of a list of all the matches that start at the first
502 nigel 77 point in the subject where there is at least one match. For example:
503    
504     re> /(tang|tangerine|tan)/
505     data> yellow tangerine\D
506     0: tangerine
507     1: tang
508     2: tan
509    
510 ph10 518 (Using the normal matching function on this data finds only "tang".)
511     The longest matching string is always given first (and numbered zero).
512 ph10 429 After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
513     lowed by the partially matching substring.
514 nigel 77
515 nigel 93 If /g is present on the pattern, the search for further matches resumes
516     at the end of the longest match. For example:
517 nigel 77
518     re> /(tang|tangerine|tan)/g
519     data> yellow tangerine and tangy sultana\D
520     0: tangerine
521     1: tang
522     2: tan
523     0: tang
524     1: tan
525     0: tan
526    
527 ph10 518 Since the matching function does not support substring capture, the
528     escape sequences that are concerned with captured substrings are not
529 nigel 77 relevant.
530    
531    
532     RESTARTING AFTER A PARTIAL MATCH
533    
534     When the alternative matching function has given the PCRE_ERROR_PARTIAL
535 ph10 518 return, indicating that the subject partially matched the pattern, you
536     can restart the match with additional subject data by means of the \R
537 nigel 77 escape sequence. For example:
538    
539 ph10 155 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
540 nigel 77 data> 23ja\P\D
541     Partial match: 23ja
542     data> n05\R\D
543     0: n05
544    
545 ph10 518 For further information about partial matching, see the pcrepartial
546 nigel 77 documentation.
547    
548    
549 nigel 75 CALLOUTS
550    
551 ph10 518 If the pattern contains any callout requests, pcretest's callout func-
552     tion is called during matching. This works with both matching func-
553 nigel 77 tions. By default, the called function displays the callout number, the
554 ph10 518 start and current positions in the text at the callout time, and the
555 nigel 77 next pattern item to be tested. For example, the output
556 nigel 75
557     --->pqrabcdef
558     0 ^ ^ \d
559    
560 ph10 518 indicates that callout number 0 occurred for a match attempt starting
561     at the fourth character of the subject string, when the pointer was at
562     the seventh character of the data, and when the next pattern item was
563     \d. Just one circumflex is output if the start and current positions
564 nigel 75 are the same.
565    
566     Callouts numbered 255 are assumed to be automatic callouts, inserted as
567 ph10 518 a result of the /C pattern modifier. In this case, instead of showing
568     the callout number, the offset in the pattern, preceded by a plus, is
569 nigel 75 output. For example:
570    
571     re> /\d?[A-E]\*/C
572     data> E*
573     --->E*
574     +0 ^ \d?
575     +3 ^ [A-E]
576     +8 ^^ \*
577     +10 ^ ^
578     0: E*
579    
580 ph10 518 The callout function in pcretest returns zero (carry on matching) by
581     default, but you can use a \C item in a data line (as described above)
582 nigel 75 to change this.
583    
584 ph10 518 Inserting callouts can be helpful when using pcretest to check compli-
585     cated regular expressions. For further information about callouts, see
586 nigel 75 the pcrecallout documentation.
587    
588    
589 nigel 93 NON-PRINTING CHARACTERS
590    
591 ph10 518 When pcretest is outputting text in the compiled version of a pattern,
592     bytes other than 32-126 are always treated as non-printing characters
593 nigel 93 are are therefore shown as hex escapes.
594    
595 ph10 518 When pcretest is outputting text that is a matched part of a subject
596     string, it behaves in the same way, unless a different locale has been
597     set for the pattern (using the /L modifier). In this case, the
598 nigel 93 isprint() function to distinguish printing and non-printing characters.
599    
600    
601 nigel 75 SAVING AND RELOADING COMPILED PATTERNS
602    
603 ph10 518 The facilities described in this section are not available when the
604 nigel 75 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
605     ifier is specified.
606    
607     When the POSIX interface is not in use, you can cause pcretest to write
608 ph10 518 a compiled pattern to a file, by following the modifiers with > and a
609 nigel 75 file name. For example:
610    
611     /pattern/im >/some/file
612    
613 ph10 518 See the pcreprecompile documentation for a discussion about saving and
614 nigel 75 re-using compiled patterns.
615    
616 ph10 518 The data that is written is binary. The first eight bytes are the
617     length of the compiled pattern data followed by the length of the
618     optional study data, each written as four bytes in big-endian order
619     (most significant byte first). If there is no study data (either the
620 nigel 75 pattern was not studied, or studying did not return any data), the sec-
621 ph10 518 ond length is zero. The lengths are followed by an exact copy of the
622 nigel 75 compiled pattern. If there is additional study data, this follows imme-
623 ph10 518 diately after the compiled pattern. After writing the file, pcretest
624 nigel 75 expects to read a new pattern.
625    
626     A saved pattern can be reloaded into pcretest by specifing < and a file
627 ph10 518 name instead of a pattern. The name of the file must not contain a <
628     character, as otherwise pcretest will interpret the line as a pattern
629 nigel 75 delimited by < characters. For example:
630    
631     re> </some/file
632     Compiled regex loaded from /some/file
633     No study data
634    
635 ph10 518 When the pattern has been loaded, pcretest proceeds to read data lines
636 nigel 75 in the usual way.
637    
638 ph10 518 You can copy a file written by pcretest to a different host and reload
639     it there, even if the new host has opposite endianness to the one on
640     which the pattern was compiled. For example, you can compile on an i86
641 nigel 75 machine and run on a SPARC machine.
642    
643 ph10 518 File names for saving and reloading can be absolute or relative, but
644     note that the shell facility of expanding a file name that starts with
645 nigel 75 a tilde (~) is not available.
646    
647 ph10 518 The ability to save and reload files in pcretest is intended for test-
648     ing and experimentation. It is not intended for production use because
649     only a single pattern can be written to a file. Furthermore, there is
650     no facility for supplying custom character tables for use with a
651     reloaded pattern. If the original pattern was compiled with custom
652     tables, an attempt to match a subject string using a reloaded pattern
653     is likely to cause pcretest to crash. Finally, if you attempt to load
654 nigel 75 a file that is not in the correct format, the result is undefined.
655    
656    
657 nigel 93 SEE ALSO
658    
659 ph10 518 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
660 nigel 93 pcrepattern(3), pcreprecompile(3).
661    
662    
663 nigel 63 AUTHOR
664 nigel 53
665 nigel 77 Philip Hazel
666 ph10 99 University Computing Service
667 nigel 93 Cambridge CB2 3QH, England.
668 nigel 53
669 ph10 99
670     REVISION
671    
672 ph10 518 Last updated: 12 May 2010
673 ph10 512 Copyright (c) 1997-2010 University of Cambridge.

Properties

Name Value
svn:eol-style native
svn:keywords "Author Date Id Revision Url"

webmaster@exim.org
ViewVC Help
Powered by ViewVC 1.1.12