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1 nigel 73 PCRETEST(1) PCRETEST(1)
2 nigel 41
4 nigel 73 NAME
5     pcretest - a program for testing Perl-compatible regular expressions.
7 nigel 79
8 nigel 53 SYNOPSIS
9 nigel 41
10 nigel 77 pcretest [-C] [-d] [-dfa] [-i] [-m] [-o osize] [-p] [-t] [source]
11 nigel 75 [destination]
13 nigel 73 pcretest was written as a test program for the PCRE regular expression
14     library itself, but it can also be used for experimenting with regular
15     expressions. This document describes the features of the test program;
16     for details of the regular expressions themselves, see the pcrepattern
17 nigel 75 documentation. For details of the PCRE library function calls and their
18     options, see the pcreapi documentation.
19 nigel 41
21 nigel 63 OPTIONS
22 nigel 41
23 nigel 73 -C Output the version number of the PCRE library, and all avail-
24     able information about the optional features that are
25     included, and then exit.
26 nigel 63
27 nigel 77 -d Behave as if each regex has the /D (debug) modifier; the
28 nigel 73 internal form is output after compilation.
29 nigel 41
30 nigel 77 -dfa Behave as if each data line contains the \D escape sequence;
31     this causes the alternative matching function,
32     pcre_dfa_exec(), to be used instead of the standard
33     pcre_exec() function (more detail is given below).
35     -i Behave as if each regex has the /I modifier; information
36 nigel 73 about the compiled pattern is given after compilation.
37 nigel 41
38 nigel 77 -m Output the size of each compiled pattern after it has been
39     compiled. This is equivalent to adding /M to each regular
40     expression. For compatibility with earlier versions of
41 nigel 73 pcretest, -s is a synonym for -m.
42 nigel 41
43 nigel 77 -o osize Set the number of elements in the output vector that is used
44     when calling pcre_exec() to be osize. The default value is
45 nigel 75 45, which is enough for 14 capturing subexpressions. The vec-
46 nigel 77 tor size can be changed for individual matching calls by
47 nigel 75 including \O in the data line (see below).
48 nigel 41
49 nigel 77 -p Behave as if each regex has the /P modifier; the POSIX wrap-
50     per API is used to call PCRE. None of the other options has
51     any effect when -p is set.
52 nigel 41
53 nigel 87 -q Do not output the version number of pcretest at the start of
54     execution.
56     -t Run each compile, study, and match many times with a timer,
57     and output resulting time per compile or match (in millisec-
58     onds). Do not set -m with -t, because you will then get the
59     size output a zillion times, and the timing will be dis-
60 nigel 75 torted.
61 nigel 49
63 nigel 63 DESCRIPTION
64 nigel 41
65 nigel 87 If pcretest is given two filename arguments, it reads from the first
66 nigel 73 and writes to the second. If it is given only one filename argument, it
67 nigel 87 reads from that file and writes to stdout. Otherwise, it reads from
68     stdin and writes to stdout, and prompts for each line of input, using
69 nigel 73 "re>" to prompt for regular expressions, and "data>" to prompt for data
70     lines.
71 nigel 41
72 nigel 73 The program handles any number of sets of input on a single input file.
73 nigel 87 Each set starts with a regular expression, and continues with any num-
74 nigel 73 ber of data lines to be matched against the pattern.
75 nigel 41
76 nigel 87 Each data line is matched separately and independently. If you want to
77     do multiple-line matches, you have to use the \n escape sequence in a
78     single line of input to encode the newline characters. The maximum
79 nigel 75 length of data line is 30,000 characters.
80 nigel 63
81 nigel 87 An empty line signals the end of the data lines, at which point a new
82     regular expression is read. The regular expressions are given enclosed
83 nigel 75 in any non-alphanumeric delimiters other than backslash, for example
84 nigel 63
85 nigel 73 /(a|bc)x+yz/
86 nigel 41
87 nigel 87 White space before the initial delimiter is ignored. A regular expres-
88     sion may be continued over several input lines, in which case the new-
89     line characters are included within it. It is possible to include the
90 nigel 73 delimiter within the pattern by escaping it, for example
91 nigel 41
92 nigel 73 /abc\/def/
93 nigel 41
94 nigel 87 If you do so, the escape and the delimiter form part of the pattern,
95     but since delimiters are always non-alphanumeric, this does not affect
96     its interpretation. If the terminating delimiter is immediately fol-
97 nigel 73 lowed by a backslash, for example,
98 nigel 41
99 nigel 73 /abc/\
100 nigel 41
101 nigel 87 then a backslash is added to the end of the pattern. This is done to
102     provide a way of testing the error condition that arises if a pattern
103 nigel 73 finishes with a backslash, because
104 nigel 49
105 nigel 73 /abc\/
106 nigel 49
107 nigel 87 is interpreted as the first line of a pattern that starts with "abc/",
108 nigel 73 causing pcretest to read the next line as a continuation of the regular
109     expression.
110 nigel 49
111 nigel 41
113 nigel 41
114 nigel 87 A pattern may be followed by any number of modifiers, which are mostly
115     single characters. Following Perl usage, these are referred to below
116     as, for example, "the /i modifier", even though the delimiter of the
117     pattern need not always be a slash, and no slash is used when writing
118     modifiers. Whitespace may appear between the final pattern delimiter
119 nigel 75 and the first modifier, and between the modifiers themselves.
120 nigel 41
121 nigel 75 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
122 nigel 87 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
123     pile() is called. These four modifier letters have the same effect as
124 nigel 75 they do in Perl. For example:
126 nigel 73 /caseless/i
127 nigel 41
128 nigel 75 The following table shows additional modifiers for setting PCRE options
129     that do not correspond to anything in Perl:
130 nigel 41
131 nigel 75 /A PCRE_ANCHORED
134 nigel 77 /f PCRE_FIRSTLINE
135 nigel 75 /N PCRE_NO_AUTO_CAPTURE
137     /X PCRE_EXTRA
139 nigel 87 Searching for all possible matches within each subject string can be
140     requested by the /g or /G modifier. After finding a match, PCRE is
141 nigel 73 called again to search the remainder of the subject string. The differ-
142     ence between /g and /G is that the former uses the startoffset argument
143 nigel 87 to pcre_exec() to start searching at a new point within the entire
144     string (which is in effect what Perl does), whereas the latter passes
145     over a shortened substring. This makes a difference to the matching
146 nigel 73 process if the pattern begins with a lookbehind assertion (including \b
147     or \B).
148 nigel 49
149 nigel 87 If any call to pcre_exec() in a /g or /G sequence matches an empty
150     string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
151     flags set in order to search for another, non-empty, match at the same
152     point. If this second match fails, the start offset is advanced by
153     one, and the normal match is retried. This imitates the way Perl han-
154 nigel 73 dles such cases when using the /g modifier or the split() function.
155 nigel 49
156 nigel 75 There are yet more modifiers for controlling the way pcretest operates.
157 nigel 49
158 nigel 87 The /+ modifier requests that as well as outputting the substring that
159     matched the entire pattern, pcretest should in addition output the
160     remainder of the subject string. This is useful for tests where the
161 nigel 73 subject contains multiple copies of the same substring.
162 nigel 41
163 nigel 87 The /L modifier must be followed directly by the name of a locale, for
164 nigel 73 example,
165 nigel 41
166 nigel 75 /pattern/Lfr_FR
167 nigel 41
168 nigel 75 For this reason, it must be the last modifier. The given locale is set,
169 nigel 87 pcre_maketables() is called to build a set of character tables for the
170     locale, and this is then passed to pcre_compile() when compiling the
171     regular expression. Without an /L modifier, NULL is passed as the
172     tables pointer; that is, /L applies only to the expression on which it
173 nigel 75 appears.
174 nigel 41
175 nigel 87 The /I modifier requests that pcretest output information about the
176     compiled pattern (whether it is anchored, has a fixed first character,
177     and so on). It does this by calling pcre_fullinfo() after compiling a
178     pattern. If the pattern is studied, the results of that are also out-
179 nigel 75 put.
180 nigel 63
181 nigel 73 The /D modifier is a PCRE debugging feature, which also assumes /I. It
182 nigel 87 causes the internal form of compiled regular expressions to be output
183 nigel 73 after compilation. If the pattern was studied, the information returned
184     is also output.
185 nigel 41
186 nigel 75 The /F modifier causes pcretest to flip the byte order of the fields in
187 nigel 87 the compiled pattern that contain 2-byte and 4-byte numbers. This
188     facility is for testing the feature in PCRE that allows it to execute
189 nigel 75 patterns that were compiled on a host with a different endianness. This
190 nigel 87 feature is not available when the POSIX interface to PCRE is being
191     used, that is, when the /P pattern modifier is specified. See also the
192 nigel 75 section about saving and reloading compiled patterns below.
194 nigel 87 The /S modifier causes pcre_study() to be called after the expression
195 nigel 73 has been compiled, and the results used when the expression is matched.
196 nigel 41
197 nigel 87 The /M modifier causes the size of memory block used to hold the com-
198 nigel 73 piled pattern to be output.
199 nigel 41
200 nigel 87 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
201     rather than its native API. When this is done, all other modifiers
202     except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present,
203     and REG_NEWLINE is set if /m is present. The wrapper functions force
204     PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
205 nigel 41
206 nigel 87 The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
207     set. This turns on support for UTF-8 character handling in PCRE, pro-
208     vided that it was compiled with this support enabled. This modifier
209 nigel 73 also causes any non-printing characters in output strings to be printed
210     using the \x{hh...} notation if they are valid UTF-8 sequences.
211 nigel 41
212 nigel 87 If the /? modifier is used with /8, it causes pcretest to call
213     pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the
214 nigel 73 checking of the string for UTF-8 validity.
215 nigel 41
216 nigel 71
217 nigel 53 DATA LINES
218 nigel 63
219 nigel 87 Before each data line is passed to pcre_exec(), leading and trailing
220     whitespace is removed, and it is then scanned for \ escapes. Some of
221     these are pretty esoteric features, intended for checking out some of
222     the more complicated features of PCRE. If you are just testing "ordi-
223     nary" regular expressions, you probably don't need any of these. The
224 nigel 73 following escapes are recognized:
225 nigel 49
226 nigel 73 \a alarm (= BEL)
227     \b backspace
228     \e escape
229     \f formfeed
230     \n newline
231     \r carriage return
232     \t tab
233     \v vertical tab
234     \nnn octal character (up to 3 octal digits)
235     \xhh hexadecimal character (up to 2 hex digits)
236     \x{hh...} hexadecimal character, any number of digits
237     in UTF-8 mode
238     \A pass the PCRE_ANCHORED option to pcre_exec()
239     \B pass the PCRE_NOTBOL option to pcre_exec()
240     \Cdd call pcre_copy_substring() for substring dd
241 nigel 75 after a successful match (number less than 32)
242 nigel 73 \Cname call pcre_copy_named_substring() for substring
243     "name" after a successful match (name termin-
244     ated by next non alphanumeric character)
245     \C+ show the current captured substrings at callout
246     time
247     \C- do not supply a callout function
248     \C!n return 1 instead of 0 when callout number n is
249     reached
250     \C!n!m return 1 instead of 0 when callout number n is
251     reached for the nth time
252     \C*n pass the number n (may be negative) as callout
253 nigel 75 data; this is used as the callout return value
254 nigel 77 \D use the pcre_dfa_exec() match function
255     \F only shortest match for pcre_dfa_exec()
256 nigel 73 \Gdd call pcre_get_substring() for substring dd
257 nigel 75 after a successful match (number less than 32)
258 nigel 73 \Gname call pcre_get_named_substring() for substring
259     "name" after a successful match (name termin-
260     ated by next non-alphanumeric character)
261     \L call pcre_get_substringlist() after a
262     successful match
263 nigel 87 \M discover the minimum MATCH_LIMIT and
264     MATCH_LIMIT_RECURSION settings
265 nigel 73 \N pass the PCRE_NOTEMPTY option to pcre_exec()
266     \Odd set the size of the output vector passed to
267 nigel 75 pcre_exec() to dd (any number of digits)
268     \P pass the PCRE_PARTIAL option to pcre_exec()
269 nigel 77 or pcre_dfa_exec()
270     \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
271 nigel 73 \S output details of memory get/free calls during matching
272     \Z pass the PCRE_NOTEOL option to pcre_exec()
273     \? pass the PCRE_NO_UTF8_CHECK option to
274     pcre_exec()
275 nigel 75 \>dd start the match at offset dd (any number of digits);
276     this sets the startoffset argument for pcre_exec()
277 nigel 71
278 nigel 87 A backslash followed by anything else just escapes the anything else.
279     If the very last character is a backslash, it is ignored. This gives a
280     way of passing an empty line as data, since a real empty line termi-
281 nigel 75 nates the data input.
283 nigel 87 If \M is present, pcretest calls pcre_exec() several times, with dif-
284     ferent values in the match_limit and match_limit_recursion fields of
285     the pcre_extra data structure, until it finds the minimum numbers for
286     each parameter that allow pcre_exec() to complete. The match_limit num-
287     ber is a measure of the amount of backtracking that takes place, and
288     checking it out can be instructive. For most simple matches, the number
289     is quite small, but for patterns with very large numbers of matching
290     possibilities, it can become large very quickly with increasing length
291     of subject string. The match_limit_recursion number is a measure of how
292     much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
293     memory is needed to complete the match attempt.
294 nigel 41
295 nigel 77 When \O is used, the value specified may be higher or lower than the
296 nigel 75 size set by the -O command line option (or defaulted to 45); \O applies
297     only to the call of pcre_exec() for the line in which it appears.
298 nigel 63
299 nigel 77 If the /P modifier was present on the pattern, causing the POSIX wrap-
300 nigel 87 per API to be used, the only option-setting sequences that have any
301     effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
302     to be passed to regexec().
303 nigel 41
304 nigel 87 The use of \x{hh...} to represent UTF-8 characters is not dependent on
305     the use of the /8 modifier on the pattern. It is recognized always.
306     There may be any number of hexadecimal digits inside the braces. The
307     result is from one to six bytes, encoded according to the UTF-8 rules.
308 nigel 41
309 nigel 53
311 nigel 53
312 nigel 87 By default, pcretest uses the standard PCRE matching function,
313 nigel 77 pcre_exec() to match each data line. From release 6.0, PCRE supports an
314 nigel 87 alternative matching function, pcre_dfa_test(), which operates in a
315     different way, and has some restrictions. The differences between the
316 nigel 77 two functions are described in the pcrematching documentation.
318 nigel 87 If a data line contains the \D escape sequence, or if the command line
319     contains the -dfa option, the alternative matching function is called.
320 nigel 77 This function finds all possible matches at a given point. If, however,
321 nigel 87 the \F escape sequence is present in the data line, it stops after the
322 nigel 77 first match is found. This is always the shortest possible match.
327 nigel 87 This section describes the output when the normal matching function,
328 nigel 77 pcre_exec(), is being used.
330 nigel 73 When a match succeeds, pcretest outputs the list of captured substrings
331 nigel 87 that pcre_exec() returns, starting with number 0 for the string that
332 nigel 75 matched the whole pattern. Otherwise, it outputs "No match" or "Partial
333 nigel 87 match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
334     TIAL, respectively, and otherwise the PCRE negative error number. Here
335 nigel 75 is an example of an interactive pcretest run.
336 nigel 53
337 nigel 73 $ pcretest
338 nigel 75 PCRE version 5.00 07-Sep-2004
339 nigel 53
340 nigel 73 re> /^abc(\d+)/
341     data> abc123
342     0: abc123
343     1: 123
344     data> xyz
345     No match
346 nigel 53
347 nigel 87 If the strings contain any non-printing characters, they are output as
348     \0x escapes, or as \x{...} escapes if the /8 modifier was present on
349     the pattern. If the pattern has the /+ modifier, the output for sub-
350     string 0 is followed by the the rest of the subject string, identified
351 nigel 75 by "0+" like this:
352 nigel 53
353 nigel 73 re> /cat/+
354     data> cataract
355     0: cat
356     0+ aract
357 nigel 53
358 nigel 87 If the pattern has the /g or /G modifier, the results of successive
359 nigel 73 matching attempts are output in sequence, like this:
360 nigel 53
361 nigel 73 re> /\Bi(\w\w)/g
362     data> Mississippi
363     0: iss
364     1: ss
365     0: iss
366     1: ss
367     0: ipp
368     1: pp
369 nigel 53
370 nigel 73 "No match" is output only if the first match attempt fails.
371 nigel 53
372 nigel 87 If any of the sequences \C, \G, or \L are present in a data line that
373     is successfully matched, the substrings extracted by the convenience
374 nigel 73 functions are output with C, G, or L after the string number instead of
375     a colon. This is in addition to the normal full list. The string length
376 nigel 87 (that is, the return from the extraction function) is given in paren-
377 nigel 73 theses after each string for \C and \G.
378 nigel 53
379 nigel 87 Note that while patterns can be continued over several lines (a plain
380 nigel 73 ">" prompt is used for continuations), data lines may not. However new-
381     lines can be included in data by means of the \n escape.
382 nigel 53
386 nigel 87 When the alternative matching function, pcre_dfa_exec(), is used (by
387     means of the \D escape sequence or the -dfa command line option), the
388     output consists of a list of all the matches that start at the first
389 nigel 77 point in the subject where there is at least one match. For example:
391     re> /(tang|tangerine|tan)/
392     data> yellow tangerine\D
393     0: tangerine
394     1: tang
395     2: tan
397 nigel 87 (Using the normal matching function on this data finds only "tang".)
398     The longest matching string is always given first (and numbered zero).
399 nigel 77
400 nigel 87 If /gP is present on the pattern, the search for further matches
401 nigel 77 resumes at the end of the longest match. For example:
403     re> /(tang|tangerine|tan)/g
404     data> yellow tangerine and tangy sultana\D
405     0: tangerine
406     1: tang
407     2: tan
408     0: tang
409     1: tan
410     0: tan
412 nigel 87 Since the matching function does not support substring capture, the
413     escape sequences that are concerned with captured substrings are not
414 nigel 77 relevant.
419     When the alternative matching function has given the PCRE_ERROR_PARTIAL
420 nigel 87 return, indicating that the subject partially matched the pattern, you
421     can restart the match with additional subject data by means of the \R
422 nigel 77 escape sequence. For example:
424     re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/
425     data> 23ja\P\D
426     Partial match: 23ja
427     data> n05\R\D
428     0: n05
430 nigel 87 For further information about partial matching, see the pcrepartial
431 nigel 77 documentation.
434 nigel 75 CALLOUTS
436 nigel 87 If the pattern contains any callout requests, pcretest's callout func-
437     tion is called during matching. This works with both matching func-
438 nigel 77 tions. By default, the called function displays the callout number, the
439 nigel 87 start and current positions in the text at the callout time, and the
440 nigel 77 next pattern item to be tested. For example, the output
441 nigel 75
442     --->pqrabcdef
443     0 ^ ^ \d
445 nigel 87 indicates that callout number 0 occurred for a match attempt starting
446     at the fourth character of the subject string, when the pointer was at
447     the seventh character of the data, and when the next pattern item was
448     \d. Just one circumflex is output if the start and current positions
449 nigel 75 are the same.
451     Callouts numbered 255 are assumed to be automatic callouts, inserted as
452 nigel 87 a result of the /C pattern modifier. In this case, instead of showing
453     the callout number, the offset in the pattern, preceded by a plus, is
454 nigel 75 output. For example:
456     re> /\d?[A-E]\*/C
457     data> E*
458     --->E*
459     +0 ^ \d?
460     +3 ^ [A-E]
461     +8 ^^ \*
462     +10 ^ ^
463     0: E*
465 nigel 87 The callout function in pcretest returns zero (carry on matching) by
466     default, but you can use a \C item in a data line (as described above)
467 nigel 75 to change this.
469 nigel 87 Inserting callouts can be helpful when using pcretest to check compli-
470     cated regular expressions. For further information about callouts, see
471 nigel 75 the pcrecallout documentation.
476 nigel 87 The facilities described in this section are not available when the
477 nigel 75 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
478     ifier is specified.
480     When the POSIX interface is not in use, you can cause pcretest to write
481 nigel 87 a compiled pattern to a file, by following the modifiers with > and a
482 nigel 75 file name. For example:
484     /pattern/im >/some/file
486 nigel 87 See the pcreprecompile documentation for a discussion about saving and
487 nigel 75 re-using compiled patterns.
489 nigel 87 The data that is written is binary. The first eight bytes are the
490     length of the compiled pattern data followed by the length of the
491     optional study data, each written as four bytes in big-endian order
492     (most significant byte first). If there is no study data (either the
493 nigel 75 pattern was not studied, or studying did not return any data), the sec-
494 nigel 87 ond length is zero. The lengths are followed by an exact copy of the
495 nigel 75 compiled pattern. If there is additional study data, this follows imme-
496 nigel 87 diately after the compiled pattern. After writing the file, pcretest
497 nigel 75 expects to read a new pattern.
499     A saved pattern can be reloaded into pcretest by specifing < and a file
500 nigel 87 name instead of a pattern. The name of the file must not contain a <
501     character, as otherwise pcretest will interpret the line as a pattern
502 nigel 75 delimited by < characters. For example:
504     re> </some/file
505     Compiled regex loaded from /some/file
506     No study data
508 nigel 87 When the pattern has been loaded, pcretest proceeds to read data lines
509 nigel 75 in the usual way.
511 nigel 87 You can copy a file written by pcretest to a different host and reload
512     it there, even if the new host has opposite endianness to the one on
513     which the pattern was compiled. For example, you can compile on an i86
514 nigel 75 machine and run on a SPARC machine.
516 nigel 87 File names for saving and reloading can be absolute or relative, but
517     note that the shell facility of expanding a file name that starts with
518 nigel 75 a tilde (~) is not available.
520 nigel 87 The ability to save and reload files in pcretest is intended for test-
521     ing and experimentation. It is not intended for production use because
522     only a single pattern can be written to a file. Furthermore, there is
523     no facility for supplying custom character tables for use with a
524     reloaded pattern. If the original pattern was compiled with custom
525     tables, an attempt to match a subject string using a reloaded pattern
526     is likely to cause pcretest to crash. Finally, if you attempt to load
527 nigel 75 a file that is not in the correct format, the result is undefined.
530 nigel 63 AUTHOR
531 nigel 53
532 nigel 77 Philip Hazel
533 nigel 73 University Computing Service,
534     Cambridge CB2 3QG, England.
535 nigel 53
536 nigel 87 Last updated: 18 January 2006
537     Copyright (c) 1997-2006 University of Cambridge.

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