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1 nigel 73 PCRETEST(1) PCRETEST(1)
2 nigel 41
3    
4 nigel 73 NAME
5     pcretest - a program for testing Perl-compatible regular expressions.
6    
7 nigel 79
8 nigel 53 SYNOPSIS
9 nigel 41
10 nigel 91 pcretest [options] [source] [destination]
11 nigel 75
12 nigel 73 pcretest was written as a test program for the PCRE regular expression
13     library itself, but it can also be used for experimenting with regular
14     expressions. This document describes the features of the test program;
15     for details of the regular expressions themselves, see the pcrepattern
16 nigel 75 documentation. For details of the PCRE library function calls and their
17     options, see the pcreapi documentation.
18 nigel 41
19    
20 nigel 63 OPTIONS
21 nigel 41
22 nigel 93 -b Behave as if each regex has the /B (show bytecode) modifier;
23     the internal form is output after compilation.
24    
25 nigel 73 -C Output the version number of the PCRE library, and all avail-
26 nigel 93 able information about the optional features that are
27 nigel 73 included, and then exit.
28 nigel 63
29 nigel 93 -d Behave as if each regex has the /D (debug) modifier; the
30     internal form and information about the compiled pattern is
31     output after compilation; -d is equivalent to -b -i.
32 nigel 41
33 nigel 77 -dfa Behave as if each data line contains the \D escape sequence;
34     this causes the alternative matching function,
35     pcre_dfa_exec(), to be used instead of the standard
36     pcre_exec() function (more detail is given below).
37    
38 nigel 93 -help Output a brief summary these options and then exit.
39    
40 nigel 77 -i Behave as if each regex has the /I modifier; information
41 nigel 73 about the compiled pattern is given after compilation.
42 nigel 41
43 ph10 392 -M Behave as if each data line contains the \M escape sequence;
44     this causes PCRE to discover the minimum MATCH_LIMIT and
45     MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
46     edly with different limits.
47    
48     -m Output the size of each compiled pattern after it has been
49     compiled. This is equivalent to adding /M to each regular
50     expression. For compatibility with earlier versions of
51 nigel 73 pcretest, -s is a synonym for -m.
52 nigel 41
53 ph10 392 -o osize Set the number of elements in the output vector that is used
54     when calling pcre_exec() or pcre_dfa_exec() to be osize. The
55     default value is 45, which is enough for 14 capturing subex-
56     pressions for pcre_exec() or 22 different matches for
57     pcre_dfa_exec(). The vector size can be changed for individ-
58     ual matching calls by including \O in the data line (see
59 nigel 93 below).
60 nigel 41
61 ph10 392 -p Behave as if each regex has the /P modifier; the POSIX wrap-
62     per API is used to call PCRE. None of the other options has
63 nigel 77 any effect when -p is set.
64 nigel 41
65 ph10 392 -q Do not output the version number of pcretest at the start of
66 nigel 87 execution.
67    
68 ph10 392 -S size On Unix-like systems, set the size of the runtime stack to
69 nigel 91 size megabytes.
70    
71 ph10 392 -t Run each compile, study, and match many times with a timer,
72     and output resulting time per compile or match (in millisec-
73     onds). Do not set -m with -t, because you will then get the
74     size output a zillion times, and the timing will be dis-
75     torted. You can control the number of iterations that are
76     used for timing by following -t with a number (as a separate
77 nigel 93 item on the command line). For example, "-t 1000" would iter-
78     ate 1000 times. The default is to iterate 500000 times.
79 nigel 49
80 nigel 93 -tm This is like -t except that it times only the matching phase,
81     not the compile or study phases.
82 nigel 49
83 nigel 93
84 nigel 63 DESCRIPTION
85 nigel 41
86 ph10 392 If pcretest is given two filename arguments, it reads from the first
87 nigel 73 and writes to the second. If it is given only one filename argument, it
88 ph10 392 reads from that file and writes to stdout. Otherwise, it reads from
89     stdin and writes to stdout, and prompts for each line of input, using
90 nigel 73 "re>" to prompt for regular expressions, and "data>" to prompt for data
91     lines.
92 nigel 41
93 ph10 392 When pcretest is built, a configuration option can specify that it
94     should be linked with the libreadline library. When this is done, if
95 ph10 289 the input is from a terminal, it is read using the readline() function.
96 ph10 392 This provides line-editing and history facilities. The output from the
97 ph10 289 -help option states whether or not readline() will be used.
98    
99 nigel 73 The program handles any number of sets of input on a single input file.
100 ph10 392 Each set starts with a regular expression, and continues with any num-
101 nigel 73 ber of data lines to be matched against the pattern.
102 nigel 41
103 ph10 392 Each data line is matched separately and independently. If you want to
104 nigel 91 do multi-line matches, you have to use the \n escape sequence (or \r or
105 nigel 93 \r\n, etc., depending on the newline setting) in a single line of input
106 ph10 392 to encode the newline sequences. There is no limit on the length of
107     data lines; the input buffer is automatically extended if it is too
108 nigel 93 small.
109 nigel 63
110 ph10 392 An empty line signals the end of the data lines, at which point a new
111     regular expression is read. The regular expressions are given enclosed
112 nigel 91 in any non-alphanumeric delimiters other than backslash, for example:
113 nigel 63
114 nigel 73 /(a|bc)x+yz/
115 nigel 41
116 ph10 392 White space before the initial delimiter is ignored. A regular expres-
117     sion may be continued over several input lines, in which case the new-
118     line characters are included within it. It is possible to include the
119 nigel 73 delimiter within the pattern by escaping it, for example
120 nigel 41
121 nigel 73 /abc\/def/
122 nigel 41
123 ph10 392 If you do so, the escape and the delimiter form part of the pattern,
124     but since delimiters are always non-alphanumeric, this does not affect
125     its interpretation. If the terminating delimiter is immediately fol-
126 nigel 73 lowed by a backslash, for example,
127 nigel 41
128 nigel 73 /abc/\
129 nigel 41
130 ph10 392 then a backslash is added to the end of the pattern. This is done to
131     provide a way of testing the error condition that arises if a pattern
132 nigel 73 finishes with a backslash, because
133 nigel 49
134 nigel 73 /abc\/
135 nigel 49
136 ph10 392 is interpreted as the first line of a pattern that starts with "abc/",
137 nigel 73 causing pcretest to read the next line as a continuation of the regular
138     expression.
139 nigel 49
140 nigel 41
141 nigel 63 PATTERN MODIFIERS
142 nigel 41
143 ph10 392 A pattern may be followed by any number of modifiers, which are mostly
144     single characters. Following Perl usage, these are referred to below
145     as, for example, "the /i modifier", even though the delimiter of the
146     pattern need not always be a slash, and no slash is used when writing
147     modifiers. Whitespace may appear between the final pattern delimiter
148 nigel 75 and the first modifier, and between the modifiers themselves.
149 nigel 41
150 nigel 75 The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
151 ph10 392 PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
152     pile() is called. These four modifier letters have the same effect as
153 nigel 75 they do in Perl. For example:
154    
155 nigel 73 /caseless/i
156 nigel 41
157 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
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 ph10 567 is advanced, and the normal match is retried. This imitates the way
209     Perl handles such cases when using the /g modifier or the split() func-
210     tion. Normally, the start offset is advanced by one character, but if
211     the newline convention recognizes CRLF as a newline, and the current
212     character is CR followed by LF, an advance of two is used.
213 nigel 49
214 nigel 91 Other modifiers
215    
216 nigel 75 There are yet more modifiers for controlling the way pcretest operates.
217 nigel 49
218 ph10 518 The /+ modifier requests that as well as outputting the substring that
219     matched the entire pattern, pcretest should in addition output the
220     remainder of the subject string. This is useful for tests where the
221 nigel 73 subject contains multiple copies of the same substring.
222 nigel 41
223 ph10 518 The /B modifier is a debugging feature. It requests that pcretest out-
224     put a representation of the compiled byte code after compilation. Nor-
225     mally this information contains length and offset values; however, if
226     /Z is also present, this data is replaced by spaces. This is a special
227 ph10 123 feature for use in the automatic test scripts; it ensures that the same
228     output is generated for different internal link sizes.
229 nigel 93
230 ph10 518 The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
231 nigel 93 that is, both the /B and the /I modifiers.
232 nigel 41
233 nigel 75 The /F modifier causes pcretest to flip the byte order of the fields in
234 ph10 518 the compiled pattern that contain 2-byte and 4-byte numbers. This
235     facility is for testing the feature in PCRE that allows it to execute
236 nigel 75 patterns that were compiled on a host with a different endianness. This
237 ph10 518 feature is not available when the POSIX interface to PCRE is being
238     used, that is, when the /P pattern modifier is specified. See also the
239 nigel 75 section about saving and reloading compiled patterns below.
240    
241 ph10 518 The /I modifier requests that pcretest output information about the
242     compiled pattern (whether it is anchored, has a fixed first character,
243     and so on). It does this by calling pcre_fullinfo() after compiling a
244     pattern. If the pattern is studied, the results of that are also out-
245 ph10 512 put.
246 nigel 41
247 ph10 518 The /K modifier requests pcretest to show names from backtracking con-
248     trol verbs that are returned from calls to pcre_exec(). It causes
249     pcretest to create a pcre_extra block if one has not already been cre-
250 ph10 512 ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
251     the mark field within it, every time that pcre_exec() is called. If the
252 ph10 518 variable that the mark field points to is non-NULL for a match, non-
253 ph10 512 match, or partial match, pcretest prints the string to which it points.
254     For a match, this is shown on a line by itself, tagged with "MK:". For
255     a non-match it is added to the message.
256    
257 ph10 518 The /L modifier must be followed directly by the name of a locale, for
258 ph10 512 example,
259    
260     /pattern/Lfr_FR
261    
262     For this reason, it must be the last modifier. The given locale is set,
263 ph10 518 pcre_maketables() is called to build a set of character tables for the
264     locale, and this is then passed to pcre_compile() when compiling the
265 ph10 545 regular expression. Without an /L (or /T) modifier, NULL is passed as
266     the tables pointer; that is, /L applies only to the expression on which
267     it appears.
268 ph10 512
269 ph10 518 The /M modifier causes the size of memory block used to hold the com-
270 nigel 73 piled pattern to be output.
271 nigel 41
272 ph10 518 The /S modifier causes pcre_study() to be called after the expression
273 ph10 512 has been compiled, and the results used when the expression is matched.
274 nigel 41
275 ph10 545 The /T modifier must be followed by a single digit. It causes a spe-
276     cific set of built-in character tables to be passed to pcre_compile().
277     It is used in the standard PCRE tests to check behaviour with different
278     character tables. The digit specifies the tables as follows:
279    
280     0 the default ASCII tables, as distributed in
281     pcre_chartables.c.dist
282     1 a set of tables defining ISO 8859 characters
283    
284     In table 1, some characters whose codes are greater than 128 are iden-
285     tified as letters, digits, spaces, etc.
286    
287 ph10 535 Using the POSIX wrapper API
288 nigel 41
289 ph10 535 The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
290     rather than its native API. When /P is set, the following modifiers set
291     options for the regcomp() function:
292    
293     /i REG_ICASE
294     /m REG_NEWLINE
295     /N REG_NOSUB
296     /s REG_DOTALL )
297     /U REG_UNGREEDY ) These options are not part of
298     /W REG_UCP ) the POSIX standard
299     /8 REG_UTF8 )
300    
301     The /+ modifier works as described above. All other modifiers are
302     ignored.
303    
304    
305 nigel 53 DATA LINES
306 nigel 63
307 ph10 535 Before each data line is passed to pcre_exec(), leading and trailing
308     whitespace is removed, and it is then scanned for \ escapes. Some of
309     these are pretty esoteric features, intended for checking out some of
310     the more complicated features of PCRE. If you are just testing "ordi-
311     nary" regular expressions, you probably don't need any of these. The
312 nigel 73 following escapes are recognized:
313 nigel 49
314 nigel 93 \a alarm (BEL, \x07)
315     \b backspace (\x08)
316     \e escape (\x27)
317     \f formfeed (\x0c)
318     \n newline (\x0a)
319 nigel 91 \qdd set the PCRE_MATCH_LIMIT limit to dd
320     (any number of digits)
321 nigel 93 \r carriage return (\x0d)
322     \t tab (\x09)
323     \v vertical tab (\x0b)
324 nigel 73 \nnn octal character (up to 3 octal digits)
325 ph10 572 always a byte unless > 255 in UTF-8 mode
326     \xhh hexadecimal byte (up to 2 hex digits)
327 nigel 73 \x{hh...} hexadecimal character, any number of digits
328     in UTF-8 mode
329     \A pass the PCRE_ANCHORED option to pcre_exec()
330 nigel 91 or pcre_dfa_exec()
331 nigel 73 \B pass the PCRE_NOTBOL option to pcre_exec()
332 nigel 91 or pcre_dfa_exec()
333 nigel 73 \Cdd call pcre_copy_substring() for substring dd
334 nigel 75 after a successful match (number less than 32)
335 nigel 73 \Cname call pcre_copy_named_substring() for substring
336     "name" after a successful match (name termin-
337     ated by next non alphanumeric character)
338     \C+ show the current captured substrings at callout
339     time
340     \C- do not supply a callout function
341     \C!n return 1 instead of 0 when callout number n is
342     reached
343     \C!n!m return 1 instead of 0 when callout number n is
344     reached for the nth time
345     \C*n pass the number n (may be negative) as callout
346 nigel 75 data; this is used as the callout return value
347 nigel 77 \D use the pcre_dfa_exec() match function
348     \F only shortest match for pcre_dfa_exec()
349 nigel 73 \Gdd call pcre_get_substring() for substring dd
350 nigel 75 after a successful match (number less than 32)
351 nigel 73 \Gname call pcre_get_named_substring() for substring
352     "name" after a successful match (name termin-
353     ated by next non-alphanumeric character)
354     \L call pcre_get_substringlist() after a
355     successful match
356 nigel 87 \M discover the minimum MATCH_LIMIT and
357     MATCH_LIMIT_RECURSION settings
358 nigel 73 \N pass the PCRE_NOTEMPTY option to pcre_exec()
359 ph10 453 or pcre_dfa_exec(); if used twice, pass the
360     PCRE_NOTEMPTY_ATSTART option
361 nigel 73 \Odd set the size of the output vector passed to
362 nigel 75 pcre_exec() to dd (any number of digits)
363 ph10 429 \P pass the PCRE_PARTIAL_SOFT option to pcre_exec()
364     or pcre_dfa_exec(); if used twice, pass the
365     PCRE_PARTIAL_HARD option
366 nigel 91 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
367     (any number of digits)
368 nigel 77 \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
369 nigel 73 \S output details of memory get/free calls during matching
370 ph10 461 \Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
371     or pcre_dfa_exec()
372 nigel 73 \Z pass the PCRE_NOTEOL option to pcre_exec()
373 nigel 91 or pcre_dfa_exec()
374 nigel 73 \? pass the PCRE_NO_UTF8_CHECK option to
375 nigel 91 pcre_exec() or pcre_dfa_exec()
376 ph10 567 \>dd start the match at offset dd (optional "-"; then
377     any number of digits); this sets the startoffset
378     argument for pcre_exec() or pcre_dfa_exec()
379 nigel 91 \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
380     or pcre_dfa_exec()
381     \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
382     or pcre_dfa_exec()
383     \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
384     or pcre_dfa_exec()
385 ph10 150 \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
386     or pcre_dfa_exec()
387 nigel 93 \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
388     or pcre_dfa_exec()
389 nigel 71
390 ph10 572 Note that \xhh always specifies one byte, even in UTF-8 mode; this
391     makes it possible to construct invalid UTF-8 sequences for testing pur-
392     poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
393     UTF-8 mode, generating more than one byte if the value is greater than
394     127. When not in UTF-8 mode, it generates one byte for values less than
395     256, and causes an error for greater values.
396    
397     The escapes that specify line ending sequences are literal strings,
398 nigel 93 exactly as shown. No more than one newline setting should be present in
399     any data line.
400 nigel 75
401 ph10 572 A backslash followed by anything else just escapes the anything else.
402     If the very last character is a backslash, it is ignored. This gives a
403     way of passing an empty line as data, since a real empty line termi-
404 nigel 93 nates the data input.
405    
406 ph10 572 If \M is present, pcretest calls pcre_exec() several times, with dif-
407     ferent values in the match_limit and match_limit_recursion fields of
408     the pcre_extra data structure, until it finds the minimum numbers for
409 nigel 87 each parameter that allow pcre_exec() to complete. The match_limit num-
410 ph10 572 ber is a measure of the amount of backtracking that takes place, and
411 nigel 87 checking it out can be instructive. For most simple matches, the number
412 ph10 572 is quite small, but for patterns with very large numbers of matching
413     possibilities, it can become large very quickly with increasing length
414 nigel 87 of subject string. The match_limit_recursion number is a measure of how
415 ph10 572 much stack (or, if PCRE is compiled with NO_RECURSE, how much heap)
416 nigel 87 memory is needed to complete the match attempt.
417 nigel 41
418 ph10 572 When \O is used, the value specified may be higher or lower than the
419 nigel 75 size set by the -O command line option (or defaulted to 45); \O applies
420     only to the call of pcre_exec() for the line in which it appears.
421 nigel 63
422 ph10 572 If the /P modifier was present on the pattern, causing the POSIX wrap-
423     per API to be used, the only option-setting sequences that have any
424     effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
425 ph10 535 REG_NOTEOL, respectively, to be passed to regexec().
426 nigel 41
427 ph10 572 The use of \x{hh...} to represent UTF-8 characters is not dependent on
428     the use of the /8 modifier on the pattern. It is recognized always.
429     There may be any number of hexadecimal digits inside the braces. The
430     result is from one to six bytes, encoded according to the original
431     UTF-8 rules of RFC 2279. This allows for values in the range 0 to
432     0x7FFFFFFF. Note that not all of those are valid Unicode code points,
433     or indeed valid UTF-8 characters according to the later rules in RFC
434 ph10 211 3629.
435 nigel 41
436 nigel 53
437 nigel 77 THE ALTERNATIVE MATCHING FUNCTION
438 nigel 53
439 ph10 572 By default, pcretest uses the standard PCRE matching function,
440 nigel 77 pcre_exec() to match each data line. From release 6.0, PCRE supports an
441 ph10 572 alternative matching function, pcre_dfa_test(), which operates in a
442     different way, and has some restrictions. The differences between the
443 nigel 77 two functions are described in the pcrematching documentation.
444    
445 ph10 572 If a data line contains the \D escape sequence, or if the command line
446     contains the -dfa option, the alternative matching function is called.
447 nigel 77 This function finds all possible matches at a given point. If, however,
448 ph10 572 the \F escape sequence is present in the data line, it stops after the
449 nigel 77 first match is found. This is always the shortest possible match.
450    
451    
452     DEFAULT OUTPUT FROM PCRETEST
453    
454 ph10 572 This section describes the output when the normal matching function,
455 nigel 77 pcre_exec(), is being used.
456    
457 nigel 73 When a match succeeds, pcretest outputs the list of captured substrings
458 ph10 572 that pcre_exec() returns, starting with number 0 for the string that
459     matched the whole pattern. Otherwise, it outputs "No match" when the
460 ph10 453 return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
461 ph10 572 tially matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
462     (Note that this is the entire substring that was inspected during the
463     partial match; it may include characters before the actual match start
464     if a lookbehind assertion, \K, \b, or \B was involved.) For any other
465     returns, it outputs the PCRE negative error number. Here is an example
466 ph10 567 of an interactive pcretest run.
467 nigel 53
468 nigel 73 $ pcretest
469 nigel 93 PCRE version 7.0 30-Nov-2006
470 nigel 53
471 nigel 73 re> /^abc(\d+)/
472     data> abc123
473     0: abc123
474     1: 123
475     data> xyz
476     No match
477 nigel 53
478 ph10 572 Note that unset capturing substrings that are not followed by one that
479     is set are not returned by pcre_exec(), and are not shown by pcretest.
480     In the following example, there are two capturing substrings, but when
481     the first data line is matched, the second, unset substring is not
482     shown. An "internal" unset substring is shown as "<unset>", as for the
483 ph10 286 second data line.
484    
485     re> /(a)|(b)/
486     data> a
487     0: a
488     1: a
489     data> b
490     0: b
491     1: <unset>
492     2: b
493    
494 ph10 572 If the strings contain any non-printing characters, they are output as
495     \0x escapes, or as \x{...} escapes if the /8 modifier was present on
496     the pattern. See below for the definition of non-printing characters.
497     If the pattern has the /+ modifier, the output for substring 0 is fol-
498     lowed by the the rest of the subject string, identified by "0+" like
499 nigel 93 this:
500 nigel 53
501 nigel 73 re> /cat/+
502     data> cataract
503     0: cat
504     0+ aract
505 nigel 53
506 ph10 572 If the pattern has the /g or /G modifier, the results of successive
507 nigel 73 matching attempts are output in sequence, like this:
508 nigel 53
509 nigel 73 re> /\Bi(\w\w)/g
510     data> Mississippi
511     0: iss
512     1: ss
513     0: iss
514     1: ss
515     0: ipp
516     1: pp
517 nigel 53
518 nigel 73 "No match" is output only if the first match attempt fails.
519 nigel 53
520 ph10 572 If any of the sequences \C, \G, or \L are present in a data line that
521     is successfully matched, the substrings extracted by the convenience
522 nigel 73 functions are output with C, G, or L after the string number instead of
523     a colon. This is in addition to the normal full list. The string length
524 ph10 572 (that is, the return from the extraction function) is given in paren-
525 nigel 73 theses after each string for \C and \G.
526 nigel 53
527 nigel 93 Note that whereas patterns can be continued over several lines (a plain
528 nigel 73 ">" prompt is used for continuations), data lines may not. However new-
529 ph10 572 lines can be included in data by means of the \n escape (or \r, \r\n,
530 nigel 93 etc., depending on the newline sequence setting).
531 nigel 53
532    
533 nigel 77 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
534    
535 ph10 572 When the alternative matching function, pcre_dfa_exec(), is used (by
536     means of the \D escape sequence or the -dfa command line option), the
537     output consists of a list of all the matches that start at the first
538 nigel 77 point in the subject where there is at least one match. For example:
539    
540     re> /(tang|tangerine|tan)/
541     data> yellow tangerine\D
542     0: tangerine
543     1: tang
544     2: tan
545    
546 ph10 572 (Using the normal matching function on this data finds only "tang".)
547     The longest matching string is always given first (and numbered zero).
548 ph10 429 After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
549 ph10 572 lowed by the partially matching substring. (Note that this is the
550     entire substring that was inspected during the partial match; it may
551 ph10 567 include characters before the actual match start if a lookbehind asser-
552     tion, \K, \b, or \B was involved.)
553 nigel 77
554 nigel 93 If /g is present on the pattern, the search for further matches resumes
555     at the end of the longest match. For example:
556 nigel 77
557     re> /(tang|tangerine|tan)/g
558     data> yellow tangerine and tangy sultana\D
559     0: tangerine
560     1: tang
561     2: tan
562     0: tang
563     1: tan
564     0: tan
565    
566 ph10 572 Since the matching function does not support substring capture, the
567     escape sequences that are concerned with captured substrings are not
568 nigel 77 relevant.
569    
570    
571     RESTARTING AFTER A PARTIAL MATCH
572    
573     When the alternative matching function has given the PCRE_ERROR_PARTIAL
574 ph10 572 return, indicating that the subject partially matched the pattern, you
575     can restart the match with additional subject data by means of the \R
576 nigel 77 escape sequence. For example:
577    
578 ph10 155 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
579 nigel 77 data> 23ja\P\D
580     Partial match: 23ja
581     data> n05\R\D
582     0: n05
583    
584 ph10 572 For further information about partial matching, see the pcrepartial
585 nigel 77 documentation.
586    
587    
588 nigel 75 CALLOUTS
589    
590 ph10 572 If the pattern contains any callout requests, pcretest's callout func-
591     tion is called during matching. This works with both matching func-
592 nigel 77 tions. By default, the called function displays the callout number, the
593 ph10 572 start and current positions in the text at the callout time, and the
594 nigel 77 next pattern item to be tested. For example, the output
595 nigel 75
596     --->pqrabcdef
597     0 ^ ^ \d
598    
599 ph10 572 indicates that callout number 0 occurred for a match attempt starting
600     at the fourth character of the subject string, when the pointer was at
601     the seventh character of the data, and when the next pattern item was
602     \d. Just one circumflex is output if the start and current positions
603 nigel 75 are the same.
604    
605     Callouts numbered 255 are assumed to be automatic callouts, inserted as
606 ph10 572 a result of the /C pattern modifier. In this case, instead of showing
607     the callout number, the offset in the pattern, preceded by a plus, is
608 nigel 75 output. For example:
609    
610     re> /\d?[A-E]\*/C
611     data> E*
612     --->E*
613     +0 ^ \d?
614     +3 ^ [A-E]
615     +8 ^^ \*
616     +10 ^ ^
617     0: E*
618    
619 ph10 572 The callout function in pcretest returns zero (carry on matching) by
620     default, but you can use a \C item in a data line (as described above)
621 nigel 75 to change this.
622    
623 ph10 572 Inserting callouts can be helpful when using pcretest to check compli-
624     cated regular expressions. For further information about callouts, see
625 nigel 75 the pcrecallout documentation.
626    
627    
628 nigel 93 NON-PRINTING CHARACTERS
629    
630 ph10 572 When pcretest is outputting text in the compiled version of a pattern,
631     bytes other than 32-126 are always treated as non-printing characters
632 nigel 93 are are therefore shown as hex escapes.
633    
634 ph10 572 When pcretest is outputting text that is a matched part of a subject
635     string, it behaves in the same way, unless a different locale has been
636     set for the pattern (using the /L modifier). In this case, the
637 nigel 93 isprint() function to distinguish printing and non-printing characters.
638    
639    
640 nigel 75 SAVING AND RELOADING COMPILED PATTERNS
641    
642 ph10 572 The facilities described in this section are not available when the
643 nigel 75 POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
644     ifier is specified.
645    
646     When the POSIX interface is not in use, you can cause pcretest to write
647 ph10 572 a compiled pattern to a file, by following the modifiers with > and a
648 nigel 75 file name. For example:
649    
650     /pattern/im >/some/file
651    
652 ph10 572 See the pcreprecompile documentation for a discussion about saving and
653 nigel 75 re-using compiled patterns.
654    
655 ph10 572 The data that is written is binary. The first eight bytes are the
656     length of the compiled pattern data followed by the length of the
657     optional study data, each written as four bytes in big-endian order
658     (most significant byte first). If there is no study data (either the
659 nigel 75 pattern was not studied, or studying did not return any data), the sec-
660 ph10 572 ond length is zero. The lengths are followed by an exact copy of the
661 nigel 75 compiled pattern. If there is additional study data, this follows imme-
662 ph10 572 diately after the compiled pattern. After writing the file, pcretest
663 nigel 75 expects to read a new pattern.
664    
665     A saved pattern can be reloaded into pcretest by specifing < and a file
666 ph10 572 name instead of a pattern. The name of the file must not contain a <
667     character, as otherwise pcretest will interpret the line as a pattern
668 nigel 75 delimited by < characters. For example:
669    
670     re> </some/file
671     Compiled regex loaded from /some/file
672     No study data
673    
674 ph10 572 When the pattern has been loaded, pcretest proceeds to read data lines
675 nigel 75 in the usual way.
676    
677 ph10 572 You can copy a file written by pcretest to a different host and reload
678     it there, even if the new host has opposite endianness to the one on
679     which the pattern was compiled. For example, you can compile on an i86
680 nigel 75 machine and run on a SPARC machine.
681    
682 ph10 572 File names for saving and reloading can be absolute or relative, but
683     note that the shell facility of expanding a file name that starts with
684 nigel 75 a tilde (~) is not available.
685    
686 ph10 572 The ability to save and reload files in pcretest is intended for test-
687     ing and experimentation. It is not intended for production use because
688     only a single pattern can be written to a file. Furthermore, there is
689     no facility for supplying custom character tables for use with a
690     reloaded pattern. If the original pattern was compiled with custom
691     tables, an attempt to match a subject string using a reloaded pattern
692     is likely to cause pcretest to crash. Finally, if you attempt to load
693 nigel 75 a file that is not in the correct format, the result is undefined.
694    
695    
696 nigel 93 SEE ALSO
697    
698 ph10 572 pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d),
699 nigel 93 pcrepattern(3), pcreprecompile(3).
700    
701    
702 nigel 63 AUTHOR
703 nigel 53
704 nigel 77 Philip Hazel
705 ph10 99 University Computing Service
706 nigel 93 Cambridge CB2 3QH, England.
707 nigel 53
708 ph10 99
709     REVISION
710    
711 ph10 572 Last updated: 07 November 2010
712 ph10 512 Copyright (c) 1997-2010 University of Cambridge.

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