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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 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
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.
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).
38 nigel 93 -help Output a brief summary these options and then exit.
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.
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.
68 ph10 392 -S size On Unix-like systems, set the size of the runtime stack to
69 nigel 91 size megabytes.
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.
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
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:
155 nigel 73 /caseless/i
156 nigel 41
157 ph10 535 The following table shows additional modifiers for setting PCRE com-
158     pile-time options 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
169 ph10 518 /W PCRE_UCP
170 ph10 231 /X PCRE_EXTRA
173 ph10 231 /<cr> PCRE_NEWLINE_CR
174     /<lf> PCRE_NEWLINE_LF
175     /<crlf> PCRE_NEWLINE_CRLF
176     /<anycrlf> PCRE_NEWLINE_ANYCRLF
177     /<any> PCRE_NEWLINE_ANY
178     /<bsr_anycrlf> PCRE_BSR_ANYCRLF
179     /<bsr_unicode> PCRE_BSR_UNICODE
180 nigel 75
181 ph10 518 The modifiers that are enclosed in angle brackets are literal strings
182     as shown, including the angle brackets, but the letters can be in
183     either case. This example sets multiline matching with CRLF as the line
184     ending sequence:
185 nigel 91
186 nigel 93 /^abc/m<crlf>
188 ph10 518 As well as turning on the PCRE_UTF8 option, the /8 modifier also causes
189     any non-printing characters in output strings to be printed using the
190     \x{hh...} notation if they are valid UTF-8 sequences. Full details of
191     the PCRE options are given in the pcreapi documentation.
192 nigel 93
193 nigel 91 Finding all matches in a string
195 ph10 518 Searching for all possible matches within each subject string can be
196     requested by the /g or /G modifier. After finding a match, PCRE is
197 nigel 73 called again to search the remainder of the subject string. The differ-
198     ence between /g and /G is that the former uses the startoffset argument
199 ph10 518 to pcre_exec() to start searching at a new point within the entire
200     string (which is in effect what Perl does), whereas the latter passes
201     over a shortened substring. This makes a difference to the matching
202 nigel 73 process if the pattern begins with a lookbehind assertion (including \b
203     or \B).
204 nigel 49
205 ph10 518 If any call to pcre_exec() in a /g or /G sequence matches an empty
206     string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
207     PCRE_ANCHORED flags set in order to search for another, non-empty,
208     match at the same point. If this second match fails, the start offset
209 ph10 567 is advanced, and the normal match is retried. This imitates the way
210     Perl handles such cases when using the /g modifier or the split() func-
211     tion. Normally, the start offset is advanced by one character, but if
212     the newline convention recognizes CRLF as a newline, and the current
213     character is CR followed by LF, an advance of two is used.
214 nigel 49
215 nigel 91 Other modifiers
217 nigel 75 There are yet more modifiers for controlling the way pcretest operates.
218 nigel 49
219 ph10 518 The /+ modifier requests that as well as outputting the substring that
220     matched the entire pattern, pcretest should in addition output the
221     remainder of the subject string. This is useful for tests where the
222 nigel 73 subject contains multiple copies of the same substring.
223 nigel 41
224 ph10 518 The /B modifier is a debugging feature. It requests that pcretest out-
225     put a representation of the compiled byte code after compilation. Nor-
226     mally this information contains length and offset values; however, if
227     /Z is also present, this data is replaced by spaces. This is a special
228 ph10 123 feature for use in the automatic test scripts; it ensures that the same
229     output is generated for different internal link sizes.
230 nigel 93
231 ph10 518 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
232 nigel 93 that is, both the /B and the /I modifiers.
233 nigel 41
234 nigel 75 The /F modifier causes pcretest to flip the byte order of the fields in
235 ph10 518 the compiled pattern that contain 2-byte and 4-byte numbers. This
236     facility is for testing the feature in PCRE that allows it to execute
237 nigel 75 patterns that were compiled on a host with a different endianness. This
238 ph10 518 feature is not available when the POSIX interface to PCRE is being
239     used, that is, when the /P pattern modifier is specified. See also the
240 nigel 75 section about saving and reloading compiled patterns below.
242 ph10 518 The /I modifier requests that pcretest output information about the
243     compiled pattern (whether it is anchored, has a fixed first character,
244     and so on). It does this by calling pcre_fullinfo() after compiling a
245     pattern. If the pattern is studied, the results of that are also out-
246 ph10 512 put.
247 nigel 41
248 ph10 518 The /K modifier requests pcretest to show names from backtracking con-
249     trol verbs that are returned from calls to pcre_exec(). It causes
250     pcretest to create a pcre_extra block if one has not already been cre-
251 ph10 512 ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
252     the mark field within it, every time that pcre_exec() is called. If the
253 ph10 518 variable that the mark field points to is non-NULL for a match, non-
254 ph10 512 match, or partial match, pcretest prints the string to which it points.
255     For a match, this is shown on a line by itself, tagged with "MK:". For
256     a non-match it is added to the message.
258 ph10 518 The /L modifier must be followed directly by the name of a locale, for
259 ph10 512 example,
261     /pattern/Lfr_FR
263     For this reason, it must be the last modifier. The given locale is set,
264 ph10 518 pcre_maketables() is called to build a set of character tables for the
265     locale, and this is then passed to pcre_compile() when compiling the
266 ph10 545 regular expression. Without an /L (or /T) modifier, NULL is passed as
267     the tables pointer; that is, /L applies only to the expression on which
268     it appears.
269 ph10 512
270 ph10 518 The /M modifier causes the size of memory block used to hold the com-
271 nigel 73 piled pattern to be output.
272 nigel 41
273 ph10 518 The /S modifier causes pcre_study() to be called after the expression
274 ph10 512 has been compiled, and the results used when the expression is matched.
275 nigel 41
276 ph10 545 The /T modifier must be followed by a single digit. It causes a spe-
277     cific set of built-in character tables to be passed to pcre_compile().
278     It is used in the standard PCRE tests to check behaviour with different
279     character tables. The digit specifies the tables as follows:
281     0 the default ASCII tables, as distributed in
282     pcre_chartables.c.dist
283     1 a set of tables defining ISO 8859 characters
285     In table 1, some characters whose codes are greater than 128 are iden-
286     tified as letters, digits, spaces, etc.
288 ph10 535 Using the POSIX wrapper API
289 nigel 41
290 ph10 535 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
291     rather than its native API. When /P is set, the following modifiers set
292     options for the regcomp() function:
294     /i REG_ICASE
295     /m REG_NEWLINE
296     /N REG_NOSUB
297     /s REG_DOTALL )
298     /U REG_UNGREEDY ) These options are not part of
299     /W REG_UCP ) the POSIX standard
300     /8 REG_UTF8 )
302     The /+ modifier works as described above. All other modifiers are
303     ignored.
306 nigel 53 DATA LINES
307 nigel 63
308 ph10 535 Before each data line is passed to pcre_exec(), leading and trailing
309     whitespace is removed, and it is then scanned for \ escapes. Some of
310     these are pretty esoteric features, intended for checking out some of
311     the more complicated features of PCRE. If you are just testing "ordi-
312     nary" regular expressions, you probably don't need any of these. The
313 nigel 73 following escapes are recognized:
314 nigel 49
315 nigel 93 \a alarm (BEL, \x07)
316     \b backspace (\x08)
317     \e escape (\x27)
318     \f formfeed (\x0c)
319     \n newline (\x0a)
320 nigel 91 \qdd set the PCRE_MATCH_LIMIT limit to dd
321     (any number of digits)
322 nigel 93 \r carriage return (\x0d)
323     \t tab (\x09)
324     \v vertical tab (\x0b)
325 nigel 73 \nnn octal character (up to 3 octal digits)
326 ph10 572 always a byte unless > 255 in UTF-8 mode
327     \xhh hexadecimal byte (up to 2 hex digits)
328 nigel 73 \x{hh...} hexadecimal character, any number of digits
329     in UTF-8 mode
330     \A pass the PCRE_ANCHORED option to pcre_exec()
331 nigel 91 or pcre_dfa_exec()
332 nigel 73 \B pass the PCRE_NOTBOL option to pcre_exec()
333 nigel 91 or pcre_dfa_exec()
334 nigel 73 \Cdd call pcre_copy_substring() for substring dd
335 nigel 75 after a successful match (number less than 32)
336 nigel 73 \Cname call pcre_copy_named_substring() for substring
337     "name" after a successful match (name termin-
338     ated by next non alphanumeric character)
339     \C+ show the current captured substrings at callout
340     time
341     \C- do not supply a callout function
342     \C!n return 1 instead of 0 when callout number n is
343     reached
344     \C!n!m return 1 instead of 0 when callout number n is
345     reached for the nth time
346     \C*n pass the number n (may be negative) as callout
347 nigel 75 data; this is used as the callout return value
348 nigel 77 \D use the pcre_dfa_exec() match function
349     \F only shortest match for pcre_dfa_exec()
350 nigel 73 \Gdd call pcre_get_substring() for substring dd
351 nigel 75 after a successful match (number less than 32)
352 nigel 73 \Gname call pcre_get_named_substring() for substring
353     "name" after a successful match (name termin-
354     ated by next non-alphanumeric character)
355     \L call pcre_get_substringlist() after a
356     successful match
357 nigel 87 \M discover the minimum MATCH_LIMIT and
358     MATCH_LIMIT_RECURSION settings
359 nigel 73 \N pass the PCRE_NOTEMPTY option to pcre_exec()
360 ph10 453 or pcre_dfa_exec(); if used twice, pass the
362 nigel 73 \Odd set the size of the output vector passed to
363 nigel 75 pcre_exec() to dd (any number of digits)
364 ph10 429 \P pass the PCRE_PARTIAL_SOFT option to pcre_exec()
365     or pcre_dfa_exec(); if used twice, pass the
366     PCRE_PARTIAL_HARD option
367 nigel 91 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
368     (any number of digits)
369 nigel 77 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
370 nigel 73 \S output details of memory get/free calls during matching
371 ph10 461 \Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
372     or pcre_dfa_exec()
373 nigel 73 \Z pass the PCRE_NOTEOL option to pcre_exec()
374 nigel 91 or pcre_dfa_exec()
375 nigel 73 \? pass the PCRE_NO_UTF8_CHECK option to
376 nigel 91 pcre_exec() or pcre_dfa_exec()
377 ph10 567 \>dd start the match at offset dd (optional "-"; then
378     any number of digits); this sets the startoffset
379     argument for pcre_exec() or pcre_dfa_exec()
380 nigel 91 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
381     or pcre_dfa_exec()
382     \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
383     or pcre_dfa_exec()
384     \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
385     or pcre_dfa_exec()
386 ph10 150 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
387     or pcre_dfa_exec()
388 nigel 93 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
389     or pcre_dfa_exec()
390 nigel 71
391 ph10 572 Note that \xhh always specifies one byte, even in UTF-8 mode; this
392     makes it possible to construct invalid UTF-8 sequences for testing pur-
393     poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
394     UTF-8 mode, generating more than one byte if the value is greater than
395     127. When not in UTF-8 mode, it generates one byte for values less than
396     256, and causes an error for greater values.
398     The escapes that specify line ending sequences are literal strings,
399 nigel 93 exactly as shown. No more than one newline setting should be present in
400     any data line.
401 nigel 75
402 ph10 572 A backslash followed by anything else just escapes the anything else.
403     If the very last character is a backslash, it is ignored. This gives a
404     way of passing an empty line as data, since a real empty line termi-
405 nigel 93 nates the data input.
407 ph10 572 If \M is present, pcretest calls pcre_exec() several times, with dif-
408     ferent values in the match_limit and match_limit_recursion fields of
409     the pcre_extra data structure, until it finds the minimum numbers for
410 nigel 87 each parameter that allow pcre_exec() to complete. The match_limit num-
411 ph10 572 ber is a measure of the amount of backtracking that takes place, and
412 nigel 87 checking it out can be instructive. For most simple matches, the number
413 ph10 572 is quite small, but for patterns with very large numbers of matching
414     possibilities, it can become large very quickly with increasing length
415 nigel 87 of subject string. The match_limit_recursion number is a measure of how
416 ph10 572 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
417 nigel 87 memory is needed to complete the match attempt.
418 nigel 41
419 ph10 572 When \O is used, the value specified may be higher or lower than the
420 nigel 75 size set by the -O command line option (or defaulted to 45); \O applies
421     only to the call of pcre_exec() for the line in which it appears.
422 nigel 63
423 ph10 572 If the /P modifier was present on the pattern, causing the POSIX wrap-
424     per API to be used, the only option-setting sequences that have any
425     effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
426 ph10 535 REG_NOTEOL, respectively, to be passed to regexec().
427 nigel 41
428 ph10 572 The use of \x{hh...} to represent UTF-8 characters is not dependent on
429     the use of the /8 modifier on the pattern. It is recognized always.
430     There may be any number of hexadecimal digits inside the braces. The
431     result is from one to six bytes, encoded according to the original
432     UTF-8 rules of RFC 2279. This allows for values in the range 0 to
433     0x7FFFFFFF. Note that not all of those are valid Unicode code points,
434     or indeed valid UTF-8 characters according to the later rules in RFC
435 ph10 211 3629.
436 nigel 41
437 nigel 53
439 nigel 53
440 ph10 572 By default, pcretest uses the standard PCRE matching function,
441 nigel 77 pcre_exec() to match each data line. From release 6.0, PCRE supports an
442 ph10 572 alternative matching function, pcre_dfa_test(), which operates in a
443     different way, and has some restrictions. The differences between the
444 nigel 77 two functions are described in the pcrematching documentation.
446 ph10 572 If a data line contains the \D escape sequence, or if the command line
447     contains the -dfa option, the alternative matching function is called.
448 nigel 77 This function finds all possible matches at a given point. If, however,
449 ph10 572 the \F escape sequence is present in the data line, it stops after the
450 nigel 77 first match is found. This is always the shortest possible match.
455 ph10 572 This section describes the output when the normal matching function,
456 nigel 77 pcre_exec(), is being used.
458 nigel 73 When a match succeeds, pcretest outputs the list of captured substrings
459 ph10 572 that pcre_exec() returns, starting with number 0 for the string that
460     matched the whole pattern. Otherwise, it outputs "No match" when the
461 ph10 453 return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
462 ph10 572 tially matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
463     (Note that this is the entire substring that was inspected during the
464     partial match; it may include characters before the actual match start
465     if a lookbehind assertion, \K, \b, or \B was involved.) For any other
466     returns, it outputs the PCRE negative error number. Here is an example
467 ph10 567 of an interactive pcretest run.
468 nigel 53
469 nigel 73 $ pcretest
470 nigel 93 PCRE version 7.0 30-Nov-2006
471 nigel 53
472 nigel 73 re> /^abc(\d+)/
473     data> abc123
474     0: abc123
475     1: 123
476     data> xyz
477     No match
478 nigel 53
479 ph10 572 Note that unset capturing substrings that are not followed by one that
480     is set are not returned by pcre_exec(), and are not shown by pcretest.
481     In the following example, there are two capturing substrings, but when
482     the first data line is matched, the second, unset substring is not
483     shown. An "internal" unset substring is shown as "<unset>", as for the
484 ph10 286 second data line.
486     re> /(a)|(b)/
487     data> a
488     0: a
489     1: a
490     data> b
491     0: b
492     1: <unset>
493     2: b
495 ph10 572 If the strings contain any non-printing characters, they are output as
496     \0x escapes, or as \x{...} escapes if the /8 modifier was present on
497     the pattern. See below for the definition of non-printing characters.
498     If the pattern has the /+ modifier, the output for substring 0 is fol-
499     lowed by the the rest of the subject string, identified by "0+" like
500 nigel 93 this:
501 nigel 53
502 nigel 73 re> /cat/+
503     data> cataract
504     0: cat
505     0+ aract
506 nigel 53
507 ph10 572 If the pattern has the /g or /G modifier, the results of successive
508 nigel 73 matching attempts are output in sequence, like this:
509 nigel 53
510 nigel 73 re> /\Bi(\w\w)/g
511     data> Mississippi
512     0: iss
513     1: ss
514     0: iss
515     1: ss
516     0: ipp
517     1: pp
518 nigel 53
519 nigel 73 "No match" is output only if the first match attempt fails.
520 nigel 53
521 ph10 572 If any of the sequences \C, \G, or \L are present in a data line that
522     is successfully matched, the substrings extracted by the convenience
523 nigel 73 functions are output with C, G, or L after the string number instead of
524     a colon. This is in addition to the normal full list. The string length
525 ph10 572 (that is, the return from the extraction function) is given in paren-
526 nigel 73 theses after each string for \C and \G.
527 nigel 53
528 nigel 93 Note that whereas patterns can be continued over several lines (a plain
529 nigel 73 ">" prompt is used for continuations), data lines may not. However new-
530 ph10 572 lines can be included in data by means of the \n escape (or \r, \r\n,
531 nigel 93 etc., depending on the newline sequence setting).
532 nigel 53
536 ph10 572 When the alternative matching function, pcre_dfa_exec(), is used (by
537     means of the \D escape sequence or the -dfa command line option), the
538     output consists of a list of all the matches that start at the first
539 nigel 77 point in the subject where there is at least one match. For example:
541     re> /(tang|tangerine|tan)/
542     data> yellow tangerine\D
543     0: tangerine
544     1: tang
545     2: tan
547 ph10 572 (Using the normal matching function on this data finds only "tang".)
548     The longest matching string is always given first (and numbered zero).
549 ph10 429 After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
550 ph10 572 lowed by the partially matching substring. (Note that this is the
551     entire substring that was inspected during the partial match; it may
552 ph10 567 include characters before the actual match start if a lookbehind asser-
553     tion, \K, \b, or \B was involved.)
554 nigel 77
555 nigel 93 If /g is present on the pattern, the search for further matches resumes
556     at the end of the longest match. For example:
557 nigel 77
558     re> /(tang|tangerine|tan)/g
559     data> yellow tangerine and tangy sultana\D
560     0: tangerine
561     1: tang
562     2: tan
563     0: tang
564     1: tan
565     0: tan
567 ph10 572 Since the matching function does not support substring capture, the
568     escape sequences that are concerned with captured substrings are not
569 nigel 77 relevant.
574     When the alternative matching function has given the PCRE_ERROR_PARTIAL
575 ph10 572 return, indicating that the subject partially matched the pattern, you
576     can restart the match with additional subject data by means of the \R
577 nigel 77 escape sequence. For example:
579 ph10 155 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
580 nigel 77 data> 23ja\P\D
581     Partial match: 23ja
582     data> n05\R\D
583     0: n05
585 ph10 572 For further information about partial matching, see the pcrepartial
586 nigel 77 documentation.
589 nigel 75 CALLOUTS
591 ph10 572 If the pattern contains any callout requests, pcretest's callout func-
592     tion is called during matching. This works with both matching func-
593 nigel 77 tions. By default, the called function displays the callout number, the
594 ph10 572 start and current positions in the text at the callout time, and the
595 nigel 77 next pattern item to be tested. For example, the output
596 nigel 75
597     --->pqrabcdef
598     0 ^ ^ \d
600 ph10 572 indicates that callout number 0 occurred for a match attempt starting
601     at the fourth character of the subject string, when the pointer was at
602     the seventh character of the data, and when the next pattern item was
603     \d. Just one circumflex is output if the start and current positions
604 nigel 75 are the same.
606     Callouts numbered 255 are assumed to be automatic callouts, inserted as
607 ph10 572 a result of the /C pattern modifier. In this case, instead of showing
608     the callout number, the offset in the pattern, preceded by a plus, is
609 nigel 75 output. For example:
611     re> /\d?[A-E]\*/C
612     data> E*
613     --->E*
614     +0 ^ \d?
615     +3 ^ [A-E]
616     +8 ^^ \*
617     +10 ^ ^
618     0: E*
620 ph10 572 The callout function in pcretest returns zero (carry on matching) by
621     default, but you can use a \C item in a data line (as described above)
622 nigel 75 to change this.
624 ph10 572 Inserting callouts can be helpful when using pcretest to check compli-
625     cated regular expressions. For further information about callouts, see
626 nigel 75 the pcrecallout documentation.
631 ph10 572 When pcretest is outputting text in the compiled version of a pattern,
632     bytes other than 32-126 are always treated as non-printing characters
633 nigel 93 are are therefore shown as hex escapes.
635 ph10 572 When pcretest is outputting text that is a matched part of a subject
636     string, it behaves in the same way, unless a different locale has been
637     set for the pattern (using the /L modifier). In this case, the
638 nigel 93 isprint() function to distinguish printing and non-printing characters.
643 ph10 572 The facilities described in this section are not available when the
644 nigel 75 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
645     ifier is specified.
647     When the POSIX interface is not in use, you can cause pcretest to write
648 ph10 572 a compiled pattern to a file, by following the modifiers with > and a
649 nigel 75 file name. For example:
651     /pattern/im >/some/file
653 ph10 572 See the pcreprecompile documentation for a discussion about saving and
654 nigel 75 re-using compiled patterns.
656 ph10 572 The data that is written is binary. The first eight bytes are the
657     length of the compiled pattern data followed by the length of the
658     optional study data, each written as four bytes in big-endian order
659     (most significant byte first). If there is no study data (either the
660 nigel 75 pattern was not studied, or studying did not return any data), the sec-
661 ph10 572 ond length is zero. The lengths are followed by an exact copy of the
662 nigel 75 compiled pattern. If there is additional study data, this follows imme-
663 ph10 572 diately after the compiled pattern. After writing the file, pcretest
664 nigel 75 expects to read a new pattern.
666     A saved pattern can be reloaded into pcretest by specifing < and a file
667 ph10 572 name instead of a pattern. The name of the file must not contain a <
668     character, as otherwise pcretest will interpret the line as a pattern
669 nigel 75 delimited by < characters. For example:
671     re> </some/file
672     Compiled regex loaded from /some/file
673     No study data
675 ph10 572 When the pattern has been loaded, pcretest proceeds to read data lines
676 nigel 75 in the usual way.
678 ph10 572 You can copy a file written by pcretest to a different host and reload
679     it there, even if the new host has opposite endianness to the one on
680     which the pattern was compiled. For example, you can compile on an i86
681 nigel 75 machine and run on a SPARC machine.
683 ph10 572 File names for saving and reloading can be absolute or relative, but
684     note that the shell facility of expanding a file name that starts with
685 nigel 75 a tilde (~) is not available.
687 ph10 572 The ability to save and reload files in pcretest is intended for test-
688     ing and experimentation. It is not intended for production use because
689     only a single pattern can be written to a file. Furthermore, there is
690     no facility for supplying custom character tables for use with a
691     reloaded pattern. If the original pattern was compiled with custom
692     tables, an attempt to match a subject string using a reloaded pattern
693     is likely to cause pcretest to crash. Finally, if you attempt to load
694 nigel 75 a file that is not in the correct format, the result is undefined.
697 nigel 93 SEE ALSO
699 ph10 572 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
700 nigel 93 pcrepattern(3), pcreprecompile(3).
703 nigel 63 AUTHOR
704 nigel 53
705 nigel 77 Philip Hazel
706 ph10 99 University Computing Service
707 nigel 93 Cambridge CB2 3QH, England.
708 nigel 53
709 ph10 99
710     REVISION
712 ph10 579 Last updated: 21 November 2010
713 ph10 512 Copyright (c) 1997-2010 University of Cambridge.


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