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1 nigel 53 .TH PCRETEST 1
2     .SH NAME
3     pcretest - a program for testing Perl-compatible regular expressions.
4     .SH SYNOPSIS
5 nigel 75 .rs
6     .sp
7 nigel 91 .B pcretest "[options] [source] [destination]"
8     .sp
9 nigel 75 \fBpcretest\fP was written as a test program for the PCRE regular expression
10 nigel 53 library itself, but it can also be used for experimenting with regular
11 nigel 63 expressions. This document describes the features of the test program; for
12     details of the regular expressions themselves, see the
13     .\" HREF
14 nigel 75 \fBpcrepattern\fP
15 nigel 63 .\"
16 nigel 75 documentation. For details of the PCRE library function calls and their
17     options, see the
18 nigel 63 .\" HREF
19 nigel 75 \fBpcreapi\fP
20 nigel 63 .\"
21     documentation.
22 nigel 75 .
23     .
24 nigel 53 .SH OPTIONS
25 nigel 63 .rs
26 nigel 53 .TP 10
27 nigel 93 \fB-b\fP
28     Behave as if each regex has the \fB/B\fP (show bytecode) modifier; the internal
29     form is output after compilation.
30     .TP 10
31 nigel 75 \fB-C\fP
32 nigel 63 Output the version number of the PCRE library, and all available information
33     about the optional features that are included, and then exit.
34     .TP 10
35 nigel 75 \fB-d\fP
36 nigel 77 Behave as if each regex has the \fB/D\fP (debug) modifier; the internal
37 nigel 93 form and information about the compiled pattern is output after compilation;
38     \fB-d\fP is equivalent to \fB-b -i\fP.
39 nigel 53 .TP 10
40 nigel 77 \fB-dfa\fP
41     Behave as if each data line contains the \eD escape sequence; this causes the
42     alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the
43     standard \fBpcre_exec()\fP function (more detail is given below).
44     .TP 10
45 nigel 93 \fB-help\fP
46     Output a brief summary these options and then exit.
47     .TP 10
48 nigel 75 \fB-i\fP
49 nigel 77 Behave as if each regex has the \fB/I\fP modifier; information about the
50 nigel 53 compiled pattern is given after compilation.
51     .TP 10
52 nigel 75 \fB-m\fP
53 nigel 53 Output the size of each compiled pattern after it has been compiled. This is
54 nigel 75 equivalent to adding \fB/M\fP to each regular expression. For compatibility
55     with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
56 nigel 53 .TP 10
57 nigel 75 \fB-o\fP \fIosize\fP
58     Set the number of elements in the output vector that is used when calling
59 nigel 93 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
60     is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
61     22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
62     changed for individual matching calls by including \eO in the data line (see
63     below).
64 nigel 53 .TP 10
65 nigel 75 \fB-p\fP
66 nigel 77 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
67     used to call PCRE. None of the other options has any effect when \fB-p\fP is
68     set.
69 nigel 53 .TP 10
70 nigel 91 \fB-q\fP
71 nigel 87 Do not output the version number of \fBpcretest\fP at the start of execution.
72     .TP 10
73 nigel 91 \fB-S\fP \fIsize\fP
74     On Unix-like systems, set the size of the runtime stack to \fIsize\fP
75     megabytes.
76     .TP 10
77 nigel 75 \fB-t\fP
78 nigel 63 Run each compile, study, and match many times with a timer, and output
79 nigel 75 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
80     \fB-t\fP, because you will then get the size output a zillion times, and the
81 nigel 93 timing will be distorted. You can control the number of iterations that are
82     used for timing by following \fB-t\fP with a number (as a separate item on the
83     command line). For example, "-t 1000" would iterate 1000 times. The default is
84     to iterate 500000 times.
85     .TP 10
86     \fB-tm\fP
87     This is like \fB-t\fP except that it times only the matching phase, not the
88     compile or study phases.
89 nigel 75 .
90     .
91 nigel 53 .SH DESCRIPTION
92 nigel 63 .rs
93     .sp
94 nigel 75 If \fBpcretest\fP is given two filename arguments, it reads from the first and
95 nigel 53 writes to the second. If it is given only one filename argument, it reads from
96     that file and writes to stdout. Otherwise, it reads from stdin and writes to
97     stdout, and prompts for each line of input, using "re>" to prompt for regular
98     expressions, and "data>" to prompt for data lines.
99 nigel 75 .P
100 nigel 53 The program handles any number of sets of input on a single input file. Each
101     set starts with a regular expression, and continues with any number of data
102 nigel 63 lines to be matched against the pattern.
103 nigel 75 .P
104     Each data line is matched separately and independently. If you want to do
105 nigel 91 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
106 nigel 93 etc., depending on the newline setting) in a single line of input to encode the
107     newline sequences. There is no limit on the length of data lines; the input
108 nigel 91 buffer is automatically extended if it is too small.
109 nigel 75 .P
110 nigel 63 An empty line signals the end of the data lines, at which point a new regular
111     expression is read. The regular expressions are given enclosed in any
112 nigel 91 non-alphanumeric delimiters other than backslash, for example:
113 nigel 75 .sp
114 nigel 53 /(a|bc)x+yz/
115 nigel 75 .sp
116 nigel 53 White space before the initial delimiter is ignored. A regular expression may
117     be continued over several input lines, in which case the newline characters are
118     included within it. It is possible to include the delimiter within the pattern
119     by escaping it, for example
120 nigel 75 .sp
121     /abc\e/def/
122     .sp
123 nigel 53 If you do so, the escape and the delimiter form part of the pattern, but since
124 nigel 75 delimiters are always non-alphanumeric, this does not affect its interpretation.
125 nigel 53 If the terminating delimiter is immediately followed by a backslash, for
126     example,
127 nigel 75 .sp
128     /abc/\e
129     .sp
130 nigel 53 then a backslash is added to the end of the pattern. This is done to provide a
131     way of testing the error condition that arises if a pattern finishes with a
132     backslash, because
133 nigel 75 .sp
134     /abc\e/
135     .sp
136 nigel 53 is interpreted as the first line of a pattern that starts with "abc/", causing
137     pcretest to read the next line as a continuation of the regular expression.
138 nigel 75 .
139     .
140     .SH "PATTERN MODIFIERS"
141 nigel 63 .rs
142     .sp
143 nigel 75 A pattern may be followed by any number of modifiers, which are mostly single
144     characters. Following Perl usage, these are referred to below as, for example,
145     "the \fB/i\fP modifier", even though the delimiter of the pattern need not
146     always be a slash, and no slash is used when writing modifiers. Whitespace may
147     appear between the final pattern delimiter and the first modifier, and between
148     the modifiers themselves.
149     .P
150     The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
151     PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
152     \fBpcre_compile()\fP is called. These four modifier letters have the same
153     effect as they do in Perl. For example:
154     .sp
155 nigel 53 /caseless/i
156 nigel 75 .sp
157     The following table shows additional modifiers for setting PCRE options that do
158     not correspond to anything in Perl:
159     .sp
160 nigel 91 \fB/A\fP PCRE_ANCHORED
161     \fB/C\fP PCRE_AUTO_CALLOUT
162     \fB/E\fP PCRE_DOLLAR_ENDONLY
163     \fB/f\fP PCRE_FIRSTLINE
164     \fB/J\fP PCRE_DUPNAMES
165     \fB/N\fP PCRE_NO_AUTO_CAPTURE
166     \fB/U\fP PCRE_UNGREEDY
167     \fB/X\fP PCRE_EXTRA
168     \fB/<cr>\fP PCRE_NEWLINE_CR
169     \fB/<lf>\fP PCRE_NEWLINE_LF
170     \fB/<crlf>\fP PCRE_NEWLINE_CRLF
171 nigel 93 \fB/<any>\fP PCRE_NEWLINE_ANY
172 nigel 75 .sp
173 nigel 93 Those specifying line ending sequencess are literal strings as shown. This
174     example sets multiline matching with CRLF as the line ending sequence:
175     .sp
176     /^abc/m<crlf>
177     .sp
178     Details of the meanings of these PCRE options are given in the
179 nigel 91 .\" HREF
180     \fBpcreapi\fP
181     .\"
182     documentation.
183     .
184     .
185     .SS "Finding all matches in a string"
186     .rs
187     .sp
188 nigel 53 Searching for all possible matches within each subject string can be requested
189 nigel 75 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
190 nigel 53 again to search the remainder of the subject string. The difference between
191 nigel 75 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
192     \fBpcre_exec()\fP to start searching at a new point within the entire string
193 nigel 53 (which is in effect what Perl does), whereas the latter passes over a shortened
194     substring. This makes a difference to the matching process if the pattern
195 nigel 75 begins with a lookbehind assertion (including \eb or \eB).
196     .P
197     If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
198 nigel 53 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
199     flags set in order to search for another, non-empty, match at the same point.
200     If this second match fails, the start offset is advanced by one, and the normal
201     match is retried. This imitates the way Perl handles such cases when using the
202 nigel 75 \fB/g\fP modifier or the \fBsplit()\fP function.
203 nigel 91 .
204     .
205     .SS "Other modifiers"
206     .rs
207     .sp
208 nigel 75 There are yet more modifiers for controlling the way \fBpcretest\fP
209 nigel 53 operates.
210 nigel 75 .P
211     The \fB/+\fP modifier requests that as well as outputting the substring that
212 nigel 53 matched the entire pattern, pcretest should in addition output the remainder of
213     the subject string. This is useful for tests where the subject contains
214     multiple copies of the same substring.
215 nigel 75 .P
216 nigel 93 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
217     output a representation of the compiled byte code after compilation.
218     .P
219 nigel 75 The \fB/L\fP modifier must be followed directly by the name of a locale, for
220 nigel 53 example,
221 nigel 75 .sp
222     /pattern/Lfr_FR
223     .sp
224     For this reason, it must be the last modifier. The given locale is set,
225     \fBpcre_maketables()\fP is called to build a set of character tables for the
226     locale, and this is then passed to \fBpcre_compile()\fP when compiling the
227     regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
228     pointer; that is, \fB/L\fP applies only to the expression on which it appears.
229     .P
230     The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
231     compiled pattern (whether it is anchored, has a fixed first character, and
232     so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
233     pattern. If the pattern is studied, the results of that are also output.
234     .P
235 nigel 93 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
236     \fB/BI\fP, that is, both the \fP/B\fP and the \fB/I\fP modifiers.
237 nigel 75 .P
238     The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
239     fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
240     facility is for testing the feature in PCRE that allows it to execute patterns
241     that were compiled on a host with a different endianness. This feature is not
242     available when the POSIX interface to PCRE is being used, that is, when the
243     \fB/P\fP pattern modifier is specified. See also the section about saving and
244     reloading compiled patterns below.
245     .P
246     The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
247 nigel 53 expression has been compiled, and the results used when the expression is
248     matched.
249 nigel 75 .P
250     The \fB/M\fP modifier causes the size of memory block used to hold the compiled
251 nigel 53 pattern to be output.
252 nigel 75 .P
253     The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
254 nigel 53 API rather than its native API. When this is done, all other modifiers except
255 nigel 75 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
256     present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
257 nigel 53 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
258 nigel 75 .P
259     The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
260 nigel 63 option set. This turns on support for UTF-8 character handling in PCRE,
261     provided that it was compiled with this support enabled. This modifier also
262     causes any non-printing characters in output strings to be printed using the
263 nigel 75 \ex{hh...} notation if they are valid UTF-8 sequences.
264     .P
265     If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
266     call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
267 nigel 71 checking of the string for UTF-8 validity.
268 nigel 75 .
269     .
270     .SH "DATA LINES"
271 nigel 63 .rs
272     .sp
273 nigel 75 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
274     whitespace is removed, and it is then scanned for \e escapes. Some of these are
275 nigel 63 pretty esoteric features, intended for checking out some of the more
276     complicated features of PCRE. If you are just testing "ordinary" regular
277     expressions, you probably don't need any of these. The following escapes are
278 nigel 53 recognized:
279 nigel 75 .sp
280 nigel 93 \ea alarm (BEL, \ex07)
281     \eb backspace (\ex08)
282     \ee escape (\ex27)
283     \ef formfeed (\ex0c)
284     \en newline (\ex0a)
285 nigel 91 .\" JOIN
286     \eqdd set the PCRE_MATCH_LIMIT limit to dd
287     (any number of digits)
288 nigel 93 \er carriage return (\ex0d)
289     \et tab (\ex09)
290     \ev vertical tab (\ex0b)
291 nigel 75 \ennn octal character (up to 3 octal digits)
292     \exhh hexadecimal character (up to 2 hex digits)
293     .\" JOIN
294     \ex{hh...} hexadecimal character, any number of digits
295 nigel 63 in UTF-8 mode
296 nigel 91 .\" JOIN
297 nigel 75 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
298 nigel 91 or \fBpcre_dfa_exec()\fP
299     .\" JOIN
300 nigel 75 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
301 nigel 91 or \fBpcre_dfa_exec()\fP
302 nigel 75 .\" JOIN
303     \eCdd call pcre_copy_substring() for substring dd
304     after a successful match (number less than 32)
305     .\" JOIN
306     \eCname call pcre_copy_named_substring() for substring
307 nigel 63 "name" after a successful match (name termin-
308     ated by next non alphanumeric character)
309 nigel 75 .\" JOIN
310     \eC+ show the current captured substrings at callout
311 nigel 63 time
312 nigel 75 \eC- do not supply a callout function
313     .\" JOIN
314     \eC!n return 1 instead of 0 when callout number n is
315 nigel 63 reached
316 nigel 75 .\" JOIN
317     \eC!n!m return 1 instead of 0 when callout number n is
318 nigel 63 reached for the nth time
319 nigel 75 .\" JOIN
320     \eC*n pass the number n (may be negative) as callout
321     data; this is used as the callout return value
322 nigel 77 \eD use the \fBpcre_dfa_exec()\fP match function
323     \eF only shortest match for \fBpcre_dfa_exec()\fP
324 nigel 75 .\" JOIN
325     \eGdd call pcre_get_substring() for substring dd
326     after a successful match (number less than 32)
327     .\" JOIN
328     \eGname call pcre_get_named_substring() for substring
329 nigel 63 "name" after a successful match (name termin-
330     ated by next non-alphanumeric character)
331 nigel 75 .\" JOIN
332     \eL call pcre_get_substringlist() after a
333 nigel 63 successful match
334 nigel 91 .\" JOIN
335 nigel 87 \eM discover the minimum MATCH_LIMIT and
336     MATCH_LIMIT_RECURSION settings
337 nigel 91 .\" JOIN
338 nigel 75 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
339 nigel 91 or \fBpcre_dfa_exec()\fP
340 nigel 75 .\" JOIN
341     \eOdd set the size of the output vector passed to
342     \fBpcre_exec()\fP to dd (any number of digits)
343 nigel 77 .\" JOIN
344 nigel 75 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
345 nigel 77 or \fBpcre_dfa_exec()\fP
346 nigel 91 .\" JOIN
347     \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
348     (any number of digits)
349 nigel 77 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
350 nigel 75 \eS output details of memory get/free calls during matching
351 nigel 91 .\" JOIN
352 nigel 75 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
353 nigel 91 or \fBpcre_dfa_exec()\fP
354 nigel 75 .\" JOIN
355     \e? pass the PCRE_NO_UTF8_CHECK option to
356 nigel 91 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
357 nigel 75 \e>dd start the match at offset dd (any number of digits);
358 nigel 91 .\" JOIN
359 nigel 75 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
360 nigel 91 or \fBpcre_dfa_exec()\fP
361     .\" JOIN
362     \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
363     or \fBpcre_dfa_exec()\fP
364     .\" JOIN
365     \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
366     or \fBpcre_dfa_exec()\fP
367     .\" JOIN
368     \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
369     or \fBpcre_dfa_exec()\fP
370 nigel 93 .\" JOIN
371     \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
372     or \fBpcre_dfa_exec()\fP
373 nigel 75 .sp
374 nigel 93 The escapes that specify line ending sequences are literal strings, exactly as
375     shown. No more than one newline setting should be present in any data line.
376 nigel 75 .P
377 nigel 93 A backslash followed by anything else just escapes the anything else. If
378     the very last character is a backslash, it is ignored. This gives a way of
379     passing an empty line as data, since a real empty line terminates the data
380     input.
381     .P
382 nigel 75 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
383 nigel 87 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
384     fields of the \fBpcre_extra\fP data structure, until it finds the minimum
385     numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
386     \fImatch_limit\fP number is a measure of the amount of backtracking that takes
387     place, and checking it out can be instructive. For most simple matches, the
388     number is quite small, but for patterns with very large numbers of matching
389     possibilities, it can become large very quickly with increasing length of
390     subject string. The \fImatch_limit_recursion\fP number is a measure of how much
391     stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
392     to complete the match attempt.
393 nigel 75 .P
394     When \eO is used, the value specified may be higher or lower than the size set
395     by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
396     the call of \fBpcre_exec()\fP for the line in which it appears.
397     .P
398     If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
399 nigel 87 API to be used, the only option-setting sequences that have any effect are \eB
400     and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
401     \fBregexec()\fP.
402 nigel 75 .P
403     The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
404     of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
405 nigel 53 any number of hexadecimal digits inside the braces. The result is from one to
406     six bytes, encoded according to the UTF-8 rules.
407 nigel 75 .
408     .
409 nigel 77 .SH "THE ALTERNATIVE MATCHING FUNCTION"
410 nigel 63 .rs
411     .sp
412 nigel 77 By default, \fBpcretest\fP uses the standard PCRE matching function,
413     \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
414     alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
415     different way, and has some restrictions. The differences between the two
416     functions are described in the
417     .\" HREF
418     \fBpcrematching\fP
419     .\"
420     documentation.
421     .P
422     If a data line contains the \eD escape sequence, or if the command line
423     contains the \fB-dfa\fP option, the alternative matching function is called.
424     This function finds all possible matches at a given point. If, however, the \eF
425     escape sequence is present in the data line, it stops after the first match is
426     found. This is always the shortest possible match.
427     .
428     .
429     .SH "DEFAULT OUTPUT FROM PCRETEST"
430     .rs
431     .sp
432     This section describes the output when the normal matching function,
433     \fBpcre_exec()\fP, is being used.
434     .P
435 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
436 nigel 75 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
437     the whole pattern. Otherwise, it outputs "No match" or "Partial match"
438     when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
439     respectively, and otherwise the PCRE negative error number. Here is an example
440 nigel 77 of an interactive \fBpcretest\fP run.
441 nigel 75 .sp
442 nigel 53 $ pcretest
443 nigel 93 PCRE version 7.0 30-Nov-2006
444 nigel 75 .sp
445     re> /^abc(\ed+)/
446 nigel 53 data> abc123
447     0: abc123
448     1: 123
449     data> xyz
450     No match
451 nigel 75 .sp
452     If the strings contain any non-printing characters, they are output as \e0x
453     escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
454 nigel 93 pattern. See below for the definition of non-printing characters. If the
455     pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
456     the the rest of the subject string, identified by "0+" like this:
457 nigel 75 .sp
458 nigel 53 re> /cat/+
459     data> cataract
460     0: cat
461     0+ aract
462 nigel 75 .sp
463     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
464 nigel 53 matching attempts are output in sequence, like this:
465 nigel 75 .sp
466     re> /\eBi(\ew\ew)/g
467 nigel 53 data> Mississippi
468     0: iss
469     1: ss
470     0: iss
471     1: ss
472     0: ipp
473     1: pp
474 nigel 75 .sp
475 nigel 53 "No match" is output only if the first match attempt fails.
476 nigel 75 .P
477     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
478 nigel 53 data line that is successfully matched, the substrings extracted by the
479     convenience functions are output with C, G, or L after the string number
480     instead of a colon. This is in addition to the normal full list. The string
481     length (that is, the return from the extraction function) is given in
482 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
483     .P
484 nigel 93 Note that whereas patterns can be continued over several lines (a plain ">"
485 nigel 53 prompt is used for continuations), data lines may not. However newlines can be
486 nigel 93 included in data by means of the \en escape (or \er, \er\en, etc., depending on
487     the newline sequence setting).
488 nigel 75 .
489     .
490 nigel 93 .
491 nigel 77 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
492     .rs
493     .sp
494     When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
495     means of the \eD escape sequence or the \fB-dfa\fP command line option), the
496     output consists of a list of all the matches that start at the first point in
497     the subject where there is at least one match. For example:
498     .sp
499     re> /(tang|tangerine|tan)/
500     data> yellow tangerine\eD
501     0: tangerine
502     1: tang
503     2: tan
504     .sp
505     (Using the normal matching function on this data finds only "tang".) The
506     longest matching string is always given first (and numbered zero).
507     .P
508 nigel 93 If \fB/g\fP is present on the pattern, the search for further matches resumes
509 nigel 77 at the end of the longest match. For example:
510     .sp
511     re> /(tang|tangerine|tan)/g
512     data> yellow tangerine and tangy sultana\eD
513     0: tangerine
514     1: tang
515     2: tan
516     0: tang
517     1: tan
518     0: tan
519     .sp
520     Since the matching function does not support substring capture, the escape
521     sequences that are concerned with captured substrings are not relevant.
522     .
523     .
524     .SH "RESTARTING AFTER A PARTIAL MATCH"
525     .rs
526     .sp
527     When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
528     indicating that the subject partially matched the pattern, you can restart the
529     match with additional subject data by means of the \eR escape sequence. For
530     example:
531     .sp
532     re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
533     data> 23ja\eP\eD
534     Partial match: 23ja
535     data> n05\eR\eD
536     0: n05
537     .sp
538     For further information about partial matching, see the
539     .\" HREF
540     \fBpcrepartial\fP
541     .\"
542     documentation.
543     .
544     .
545 nigel 75 .SH CALLOUTS
546     .rs
547     .sp
548     If the pattern contains any callout requests, \fBpcretest\fP's callout function
549 nigel 77 is called during matching. This works with both matching functions. By default,
550     the called function displays the callout number, the start and current
551     positions in the text at the callout time, and the next pattern item to be
552     tested. For example, the output
553 nigel 75 .sp
554     --->pqrabcdef
555     0 ^ ^ \ed
556     .sp
557     indicates that callout number 0 occurred for a match attempt starting at the
558     fourth character of the subject string, when the pointer was at the seventh
559     character of the data, and when the next pattern item was \ed. Just one
560     circumflex is output if the start and current positions are the same.
561     .P
562     Callouts numbered 255 are assumed to be automatic callouts, inserted as a
563     result of the \fB/C\fP pattern modifier. In this case, instead of showing the
564     callout number, the offset in the pattern, preceded by a plus, is output. For
565     example:
566     .sp
567     re> /\ed?[A-E]\e*/C
568     data> E*
569     --->E*
570     +0 ^ \ed?
571     +3 ^ [A-E]
572     +8 ^^ \e*
573     +10 ^ ^
574     0: E*
575     .sp
576     The callout function in \fBpcretest\fP returns zero (carry on matching) by
577 nigel 77 default, but you can use a \eC item in a data line (as described above) to
578 nigel 75 change this.
579     .P
580     Inserting callouts can be helpful when using \fBpcretest\fP to check
581     complicated regular expressions. For further information about callouts, see
582     the
583     .\" HREF
584     \fBpcrecallout\fP
585     .\"
586     documentation.
587     .
588     .
589 nigel 93 .
590     .SH "NON-PRINTING CHARACTERS"
591     .rs
592     .sp
593     When \fBpcretest\fP is outputting text in the compiled version of a pattern,
594     bytes other than 32-126 are always treated as non-printing characters are are
595     therefore shown as hex escapes.
596     .P
597     When \fBpcretest\fP is outputting text that is a matched part of a subject
598     string, it behaves in the same way, unless a different locale has been set for
599     the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
600     function to distinguish printing and non-printing characters.
601     .
602     .
603     .
604 nigel 75 .SH "SAVING AND RELOADING COMPILED PATTERNS"
605     .rs
606     .sp
607     The facilities described in this section are not available when the POSIX
608     inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
609     specified.
610     .P
611     When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
612     compiled pattern to a file, by following the modifiers with > and a file name.
613     For example:
614     .sp
615     /pattern/im >/some/file
616     .sp
617     See the
618     .\" HREF
619     \fBpcreprecompile\fP
620     .\"
621     documentation for a discussion about saving and re-using compiled patterns.
622     .P
623     The data that is written is binary. The first eight bytes are the length of the
624     compiled pattern data followed by the length of the optional study data, each
625     written as four bytes in big-endian order (most significant byte first). If
626     there is no study data (either the pattern was not studied, or studying did not
627     return any data), the second length is zero. The lengths are followed by an
628     exact copy of the compiled pattern. If there is additional study data, this
629     follows immediately after the compiled pattern. After writing the file,
630     \fBpcretest\fP expects to read a new pattern.
631     .P
632     A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
633     name instead of a pattern. The name of the file must not contain a < character,
634     as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
635     characters.
636     For example:
637     .sp
638     re> </some/file
639     Compiled regex loaded from /some/file
640     No study data
641     .sp
642     When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
643     the usual way.
644     .P
645     You can copy a file written by \fBpcretest\fP to a different host and reload it
646     there, even if the new host has opposite endianness to the one on which the
647     pattern was compiled. For example, you can compile on an i86 machine and run on
648     a SPARC machine.
649     .P
650     File names for saving and reloading can be absolute or relative, but note that
651     the shell facility of expanding a file name that starts with a tilde (~) is not
652     available.
653     .P
654     The ability to save and reload files in \fBpcretest\fP is intended for testing
655     and experimentation. It is not intended for production use because only a
656     single pattern can be written to a file. Furthermore, there is no facility for
657     supplying custom character tables for use with a reloaded pattern. If the
658     original pattern was compiled with custom tables, an attempt to match a subject
659     string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
660     Finally, if you attempt to load a file that is not in the correct format, the
661     result is undefined.
662     .
663     .
664 nigel 93 .SH "SEE ALSO"
665     .rs
666     .sp
667     \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
668     \fBpcrepartial\fP(d), \fPpcrepattern\fP(3), \fBpcreprecompile\fP(3).
669     .
670     .
671 nigel 53 .SH AUTHOR
672 nigel 63 .rs
673     .sp
674 nigel 77 Philip Hazel
675 nigel 53 .br
676     University Computing Service,
677     .br
678 nigel 93 Cambridge CB2 3QH, England.
679 nigel 75 .P
680 nigel 63 .in 0
681 nigel 93 Last updated: 30 November 2006
682 nigel 53 .br
683 nigel 87 Copyright (c) 1997-2006 University of Cambridge.

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