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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 75 \fB-C\fP
28 nigel 63 Output the version number of the PCRE library, and all available information
29     about the optional features that are included, and then exit.
30     .TP 10
31 nigel 75 \fB-d\fP
32 nigel 77 Behave as if each regex has the \fB/D\fP (debug) modifier; the internal
33 nigel 53 form is output after compilation.
34     .TP 10
35 nigel 77 \fB-dfa\fP
36     Behave as if each data line contains the \eD escape sequence; this causes the
37     alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the
38     standard \fBpcre_exec()\fP function (more detail is given below).
39     .TP 10
40 nigel 75 \fB-i\fP
41 nigel 77 Behave as if each regex has the \fB/I\fP modifier; information about the
42 nigel 53 compiled pattern is given after compilation.
43     .TP 10
44 nigel 75 \fB-m\fP
45 nigel 53 Output the size of each compiled pattern after it has been compiled. This is
46 nigel 75 equivalent to adding \fB/M\fP to each regular expression. For compatibility
47     with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
48 nigel 53 .TP 10
49 nigel 75 \fB-o\fP \fIosize\fP
50     Set the number of elements in the output vector that is used when calling
51     \fBpcre_exec()\fP to be \fIosize\fP. The default value is 45, which is enough
52     for 14 capturing subexpressions. The vector size can be changed for individual
53     matching calls by including \eO in the data line (see below).
54 nigel 53 .TP 10
55 nigel 75 \fB-p\fP
56 nigel 77 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
57     used to call PCRE. None of the other options has any effect when \fB-p\fP is
58     set.
59 nigel 53 .TP 10
60 nigel 91 \fB-q\fP
61 nigel 87 Do not output the version number of \fBpcretest\fP at the start of execution.
62     .TP 10
63 nigel 91 \fB-S\fP \fIsize\fP
64     On Unix-like systems, set the size of the runtime stack to \fIsize\fP
65     megabytes.
66     .TP 10
67 nigel 75 \fB-t\fP
68 nigel 63 Run each compile, study, and match many times with a timer, and output
69 nigel 75 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
70     \fB-t\fP, because you will then get the size output a zillion times, and the
71     timing will be distorted.
72     .
73     .
74 nigel 53 .SH DESCRIPTION
75 nigel 63 .rs
76     .sp
77 nigel 75 If \fBpcretest\fP is given two filename arguments, it reads from the first and
78 nigel 53 writes to the second. If it is given only one filename argument, it reads from
79     that file and writes to stdout. Otherwise, it reads from stdin and writes to
80     stdout, and prompts for each line of input, using "re>" to prompt for regular
81     expressions, and "data>" to prompt for data lines.
82 nigel 75 .P
83 nigel 53 The program handles any number of sets of input on a single input file. Each
84     set starts with a regular expression, and continues with any number of data
85 nigel 63 lines to be matched against the pattern.
86 nigel 75 .P
87     Each data line is matched separately and independently. If you want to do
88 nigel 91 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
89     depending on the newline setting) in a single line of input to encode the
90     newline characters. There is no limit on the length of data lines; the input
91     buffer is automatically extended if it is too small.
92 nigel 75 .P
93 nigel 63 An empty line signals the end of the data lines, at which point a new regular
94     expression is read. The regular expressions are given enclosed in any
95 nigel 91 non-alphanumeric delimiters other than backslash, for example:
96 nigel 75 .sp
97 nigel 53 /(a|bc)x+yz/
98 nigel 75 .sp
99 nigel 53 White space before the initial delimiter is ignored. A regular expression may
100     be continued over several input lines, in which case the newline characters are
101     included within it. It is possible to include the delimiter within the pattern
102     by escaping it, for example
103 nigel 75 .sp
104     /abc\e/def/
105     .sp
106 nigel 53 If you do so, the escape and the delimiter form part of the pattern, but since
107 nigel 75 delimiters are always non-alphanumeric, this does not affect its interpretation.
108 nigel 53 If the terminating delimiter is immediately followed by a backslash, for
109     example,
110 nigel 75 .sp
111     /abc/\e
112     .sp
113 nigel 53 then a backslash is added to the end of the pattern. This is done to provide a
114     way of testing the error condition that arises if a pattern finishes with a
115     backslash, because
116 nigel 75 .sp
117     /abc\e/
118     .sp
119 nigel 53 is interpreted as the first line of a pattern that starts with "abc/", causing
120     pcretest to read the next line as a continuation of the regular expression.
121 nigel 75 .
122     .
123     .SH "PATTERN MODIFIERS"
124 nigel 63 .rs
125     .sp
126 nigel 75 A pattern may be followed by any number of modifiers, which are mostly single
127     characters. Following Perl usage, these are referred to below as, for example,
128     "the \fB/i\fP modifier", even though the delimiter of the pattern need not
129     always be a slash, and no slash is used when writing modifiers. Whitespace may
130     appear between the final pattern delimiter and the first modifier, and between
131     the modifiers themselves.
132     .P
133     The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
134     PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
135     \fBpcre_compile()\fP is called. These four modifier letters have the same
136     effect as they do in Perl. For example:
137     .sp
138 nigel 53 /caseless/i
139 nigel 75 .sp
140     The following table shows additional modifiers for setting PCRE options that do
141     not correspond to anything in Perl:
142     .sp
143 nigel 91 \fB/A\fP PCRE_ANCHORED
144     \fB/C\fP PCRE_AUTO_CALLOUT
145     \fB/E\fP PCRE_DOLLAR_ENDONLY
146     \fB/f\fP PCRE_FIRSTLINE
147     \fB/J\fP PCRE_DUPNAMES
148     \fB/N\fP PCRE_NO_AUTO_CAPTURE
149     \fB/U\fP PCRE_UNGREEDY
150     \fB/X\fP PCRE_EXTRA
151     \fB/<cr>\fP PCRE_NEWLINE_CR
152     \fB/<lf>\fP PCRE_NEWLINE_LF
153     \fB/<crlf>\fP PCRE_NEWLINE_CRLF
154 nigel 75 .sp
155 nigel 91 Those specifying line endings are literal strings as shown. Details of the
156     meanings of these PCRE options are given in the
157     .\" HREF
158     \fBpcreapi\fP
159     .\"
160     documentation.
161     .
162     .
163     .SS "Finding all matches in a string"
164     .rs
165     .sp
166 nigel 53 Searching for all possible matches within each subject string can be requested
167 nigel 75 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
168 nigel 53 again to search the remainder of the subject string. The difference between
169 nigel 75 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
170     \fBpcre_exec()\fP to start searching at a new point within the entire string
171 nigel 53 (which is in effect what Perl does), whereas the latter passes over a shortened
172     substring. This makes a difference to the matching process if the pattern
173 nigel 75 begins with a lookbehind assertion (including \eb or \eB).
174     .P
175     If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
176 nigel 53 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
177     flags set in order to search for another, non-empty, match at the same point.
178     If this second match fails, the start offset is advanced by one, and the normal
179     match is retried. This imitates the way Perl handles such cases when using the
180 nigel 75 \fB/g\fP modifier or the \fBsplit()\fP function.
181 nigel 91 .
182     .
183     .SS "Other modifiers"
184     .rs
185     .sp
186 nigel 75 There are yet more modifiers for controlling the way \fBpcretest\fP
187 nigel 53 operates.
188 nigel 75 .P
189     The \fB/+\fP modifier requests that as well as outputting the substring that
190 nigel 53 matched the entire pattern, pcretest should in addition output the remainder of
191     the subject string. This is useful for tests where the subject contains
192     multiple copies of the same substring.
193 nigel 75 .P
194     The \fB/L\fP modifier must be followed directly by the name of a locale, for
195 nigel 53 example,
196 nigel 75 .sp
197     /pattern/Lfr_FR
198     .sp
199     For this reason, it must be the last modifier. The given locale is set,
200     \fBpcre_maketables()\fP is called to build a set of character tables for the
201     locale, and this is then passed to \fBpcre_compile()\fP when compiling the
202     regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
203     pointer; that is, \fB/L\fP applies only to the expression on which it appears.
204     .P
205     The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
206     compiled pattern (whether it is anchored, has a fixed first character, and
207     so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
208     pattern. If the pattern is studied, the results of that are also output.
209     .P
210     The \fB/D\fP modifier is a PCRE debugging feature, which also assumes \fB/I\fP.
211 nigel 53 It causes the internal form of compiled regular expressions to be output after
212 nigel 63 compilation. If the pattern was studied, the information returned is also
213     output.
214 nigel 75 .P
215     The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
216     fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
217     facility is for testing the feature in PCRE that allows it to execute patterns
218     that were compiled on a host with a different endianness. This feature is not
219     available when the POSIX interface to PCRE is being used, that is, when the
220     \fB/P\fP pattern modifier is specified. See also the section about saving and
221     reloading compiled patterns below.
222     .P
223     The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
224 nigel 53 expression has been compiled, and the results used when the expression is
225     matched.
226 nigel 75 .P
227     The \fB/M\fP modifier causes the size of memory block used to hold the compiled
228 nigel 53 pattern to be output.
229 nigel 75 .P
230     The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
231 nigel 53 API rather than its native API. When this is done, all other modifiers except
232 nigel 75 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
233     present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
234 nigel 53 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
235 nigel 75 .P
236     The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
237 nigel 63 option set. This turns on support for UTF-8 character handling in PCRE,
238     provided that it was compiled with this support enabled. This modifier also
239     causes any non-printing characters in output strings to be printed using the
240 nigel 75 \ex{hh...} notation if they are valid UTF-8 sequences.
241     .P
242     If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
243     call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
244 nigel 71 checking of the string for UTF-8 validity.
245 nigel 75 .
246     .
247     .SH "DATA LINES"
248 nigel 63 .rs
249     .sp
250 nigel 75 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
251     whitespace is removed, and it is then scanned for \e escapes. Some of these are
252 nigel 63 pretty esoteric features, intended for checking out some of the more
253     complicated features of PCRE. If you are just testing "ordinary" regular
254     expressions, you probably don't need any of these. The following escapes are
255 nigel 53 recognized:
256 nigel 75 .sp
257     \ea alarm (= BEL)
258     \eb backspace
259     \ee escape
260     \ef formfeed
261     \en newline
262 nigel 91 .\" JOIN
263     \eqdd set the PCRE_MATCH_LIMIT limit to dd
264     (any number of digits)
265 nigel 75 \er carriage return
266     \et tab
267     \ev vertical tab
268     \ennn octal character (up to 3 octal digits)
269     \exhh hexadecimal character (up to 2 hex digits)
270     .\" JOIN
271     \ex{hh...} hexadecimal character, any number of digits
272 nigel 63 in UTF-8 mode
273 nigel 91 .\" JOIN
274 nigel 75 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
275 nigel 91 or \fBpcre_dfa_exec()\fP
276     .\" JOIN
277 nigel 75 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
278 nigel 91 or \fBpcre_dfa_exec()\fP
279 nigel 75 .\" JOIN
280     \eCdd call pcre_copy_substring() for substring dd
281     after a successful match (number less than 32)
282     .\" JOIN
283     \eCname call pcre_copy_named_substring() for substring
284 nigel 63 "name" after a successful match (name termin-
285     ated by next non alphanumeric character)
286 nigel 75 .\" JOIN
287     \eC+ show the current captured substrings at callout
288 nigel 63 time
289 nigel 75 \eC- do not supply a callout function
290     .\" JOIN
291     \eC!n return 1 instead of 0 when callout number n is
292 nigel 63 reached
293 nigel 75 .\" JOIN
294     \eC!n!m return 1 instead of 0 when callout number n is
295 nigel 63 reached for the nth time
296 nigel 75 .\" JOIN
297     \eC*n pass the number n (may be negative) as callout
298     data; this is used as the callout return value
299 nigel 77 \eD use the \fBpcre_dfa_exec()\fP match function
300     \eF only shortest match for \fBpcre_dfa_exec()\fP
301 nigel 75 .\" JOIN
302     \eGdd call pcre_get_substring() for substring dd
303     after a successful match (number less than 32)
304     .\" JOIN
305     \eGname call pcre_get_named_substring() for substring
306 nigel 63 "name" after a successful match (name termin-
307     ated by next non-alphanumeric character)
308 nigel 75 .\" JOIN
309     \eL call pcre_get_substringlist() after a
310 nigel 63 successful match
311 nigel 91 .\" JOIN
312 nigel 87 \eM discover the minimum MATCH_LIMIT and
313     MATCH_LIMIT_RECURSION settings
314 nigel 91 .\" JOIN
315 nigel 75 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
316 nigel 91 or \fBpcre_dfa_exec()\fP
317 nigel 75 .\" JOIN
318     \eOdd set the size of the output vector passed to
319     \fBpcre_exec()\fP to dd (any number of digits)
320 nigel 77 .\" JOIN
321 nigel 75 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
322 nigel 77 or \fBpcre_dfa_exec()\fP
323 nigel 91 .\" JOIN
324     \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
325     (any number of digits)
326 nigel 77 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
327 nigel 75 \eS output details of memory get/free calls during matching
328 nigel 91 .\" JOIN
329 nigel 75 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
330 nigel 91 or \fBpcre_dfa_exec()\fP
331 nigel 75 .\" JOIN
332     \e? pass the PCRE_NO_UTF8_CHECK option to
333 nigel 91 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
334 nigel 75 \e>dd start the match at offset dd (any number of digits);
335 nigel 91 .\" JOIN
336 nigel 75 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
337 nigel 91 or \fBpcre_dfa_exec()\fP
338     .\" JOIN
339     \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
340     or \fBpcre_dfa_exec()\fP
341     .\" JOIN
342     \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
343     or \fBpcre_dfa_exec()\fP
344     .\" JOIN
345     \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
346     or \fBpcre_dfa_exec()\fP
347 nigel 75 .sp
348 nigel 91 The escapes that specify line endings are literal strings, exactly as shown.
349 nigel 75 A backslash followed by anything else just escapes the anything else. If the
350     very last character is a backslash, it is ignored. This gives a way of passing
351     an empty line as data, since a real empty line terminates the data input.
352     .P
353     If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
354 nigel 87 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
355     fields of the \fBpcre_extra\fP data structure, until it finds the minimum
356     numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
357     \fImatch_limit\fP number is a measure of the amount of backtracking that takes
358     place, and checking it out can be instructive. For most simple matches, the
359     number is quite small, but for patterns with very large numbers of matching
360     possibilities, it can become large very quickly with increasing length of
361     subject string. The \fImatch_limit_recursion\fP number is a measure of how much
362     stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
363     to complete the match attempt.
364 nigel 75 .P
365     When \eO is used, the value specified may be higher or lower than the size set
366     by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
367     the call of \fBpcre_exec()\fP for the line in which it appears.
368     .P
369     If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
370 nigel 87 API to be used, the only option-setting sequences that have any effect are \eB
371     and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
372     \fBregexec()\fP.
373 nigel 75 .P
374     The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
375     of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
376 nigel 53 any number of hexadecimal digits inside the braces. The result is from one to
377     six bytes, encoded according to the UTF-8 rules.
378 nigel 75 .
379     .
380 nigel 77 .SH "THE ALTERNATIVE MATCHING FUNCTION"
381 nigel 63 .rs
382     .sp
383 nigel 77 By default, \fBpcretest\fP uses the standard PCRE matching function,
384     \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
385     alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
386     different way, and has some restrictions. The differences between the two
387     functions are described in the
388     .\" HREF
389     \fBpcrematching\fP
390     .\"
391     documentation.
392     .P
393     If a data line contains the \eD escape sequence, or if the command line
394     contains the \fB-dfa\fP option, the alternative matching function is called.
395     This function finds all possible matches at a given point. If, however, the \eF
396     escape sequence is present in the data line, it stops after the first match is
397     found. This is always the shortest possible match.
398     .
399     .
400     .SH "DEFAULT OUTPUT FROM PCRETEST"
401     .rs
402     .sp
403     This section describes the output when the normal matching function,
404     \fBpcre_exec()\fP, is being used.
405     .P
406 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
407 nigel 75 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
408     the whole pattern. Otherwise, it outputs "No match" or "Partial match"
409     when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
410     respectively, and otherwise the PCRE negative error number. Here is an example
411 nigel 77 of an interactive \fBpcretest\fP run.
412 nigel 75 .sp
413 nigel 53 $ pcretest
414 nigel 75 PCRE version 5.00 07-Sep-2004
415     .sp
416     re> /^abc(\ed+)/
417 nigel 53 data> abc123
418     0: abc123
419     1: 123
420     data> xyz
421     No match
422 nigel 75 .sp
423     If the strings contain any non-printing characters, they are output as \e0x
424     escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
425     pattern. If the pattern has the \fB/+\fP modifier, the output for substring 0
426     is followed by the the rest of the subject string, identified by "0+" like
427     this:
428     .sp
429 nigel 53 re> /cat/+
430     data> cataract
431     0: cat
432     0+ aract
433 nigel 75 .sp
434     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
435 nigel 53 matching attempts are output in sequence, like this:
436 nigel 75 .sp
437     re> /\eBi(\ew\ew)/g
438 nigel 53 data> Mississippi
439     0: iss
440     1: ss
441     0: iss
442     1: ss
443     0: ipp
444     1: pp
445 nigel 75 .sp
446 nigel 53 "No match" is output only if the first match attempt fails.
447 nigel 75 .P
448     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
449 nigel 53 data line that is successfully matched, the substrings extracted by the
450     convenience functions are output with C, G, or L after the string number
451     instead of a colon. This is in addition to the normal full list. The string
452     length (that is, the return from the extraction function) is given in
453 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
454     .P
455 nigel 53 Note that while patterns can be continued over several lines (a plain ">"
456     prompt is used for continuations), data lines may not. However newlines can be
457 nigel 91 included in data by means of the \en escape (or \er or \er\en for those newline
458     settings).
459 nigel 75 .
460     .
461 nigel 77 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
462     .rs
463     .sp
464     When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
465     means of the \eD escape sequence or the \fB-dfa\fP command line option), the
466     output consists of a list of all the matches that start at the first point in
467     the subject where there is at least one match. For example:
468     .sp
469     re> /(tang|tangerine|tan)/
470     data> yellow tangerine\eD
471     0: tangerine
472     1: tang
473     2: tan
474     .sp
475     (Using the normal matching function on this data finds only "tang".) The
476     longest matching string is always given first (and numbered zero).
477     .P
478     If \fB/g\P is present on the pattern, the search for further matches resumes
479     at the end of the longest match. For example:
480     .sp
481     re> /(tang|tangerine|tan)/g
482     data> yellow tangerine and tangy sultana\eD
483     0: tangerine
484     1: tang
485     2: tan
486     0: tang
487     1: tan
488     0: tan
489     .sp
490     Since the matching function does not support substring capture, the escape
491     sequences that are concerned with captured substrings are not relevant.
492     .
493     .
494     .SH "RESTARTING AFTER A PARTIAL MATCH"
495     .rs
496     .sp
497     When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
498     indicating that the subject partially matched the pattern, you can restart the
499     match with additional subject data by means of the \eR escape sequence. For
500     example:
501     .sp
502     re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
503     data> 23ja\eP\eD
504     Partial match: 23ja
505     data> n05\eR\eD
506     0: n05
507     .sp
508     For further information about partial matching, see the
509     .\" HREF
510     \fBpcrepartial\fP
511     .\"
512     documentation.
513     .
514     .
515 nigel 75 .SH CALLOUTS
516     .rs
517     .sp
518     If the pattern contains any callout requests, \fBpcretest\fP's callout function
519 nigel 77 is called during matching. This works with both matching functions. By default,
520     the called function displays the callout number, the start and current
521     positions in the text at the callout time, and the next pattern item to be
522     tested. For example, the output
523 nigel 75 .sp
524     --->pqrabcdef
525     0 ^ ^ \ed
526     .sp
527     indicates that callout number 0 occurred for a match attempt starting at the
528     fourth character of the subject string, when the pointer was at the seventh
529     character of the data, and when the next pattern item was \ed. Just one
530     circumflex is output if the start and current positions are the same.
531     .P
532     Callouts numbered 255 are assumed to be automatic callouts, inserted as a
533     result of the \fB/C\fP pattern modifier. In this case, instead of showing the
534     callout number, the offset in the pattern, preceded by a plus, is output. For
535     example:
536     .sp
537     re> /\ed?[A-E]\e*/C
538     data> E*
539     --->E*
540     +0 ^ \ed?
541     +3 ^ [A-E]
542     +8 ^^ \e*
543     +10 ^ ^
544     0: E*
545     .sp
546     The callout function in \fBpcretest\fP returns zero (carry on matching) by
547 nigel 77 default, but you can use a \eC item in a data line (as described above) to
548 nigel 75 change this.
549     .P
550     Inserting callouts can be helpful when using \fBpcretest\fP to check
551     complicated regular expressions. For further information about callouts, see
552     the
553     .\" HREF
554     \fBpcrecallout\fP
555     .\"
556     documentation.
557     .
558     .
559     .SH "SAVING AND RELOADING COMPILED PATTERNS"
560     .rs
561     .sp
562     The facilities described in this section are not available when the POSIX
563     inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
564     specified.
565     .P
566     When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
567     compiled pattern to a file, by following the modifiers with > and a file name.
568     For example:
569     .sp
570     /pattern/im >/some/file
571     .sp
572     See the
573     .\" HREF
574     \fBpcreprecompile\fP
575     .\"
576     documentation for a discussion about saving and re-using compiled patterns.
577     .P
578     The data that is written is binary. The first eight bytes are the length of the
579     compiled pattern data followed by the length of the optional study data, each
580     written as four bytes in big-endian order (most significant byte first). If
581     there is no study data (either the pattern was not studied, or studying did not
582     return any data), the second length is zero. The lengths are followed by an
583     exact copy of the compiled pattern. If there is additional study data, this
584     follows immediately after the compiled pattern. After writing the file,
585     \fBpcretest\fP expects to read a new pattern.
586     .P
587     A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
588     name instead of a pattern. The name of the file must not contain a < character,
589     as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
590     characters.
591     For example:
592     .sp
593     re> </some/file
594     Compiled regex loaded from /some/file
595     No study data
596     .sp
597     When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
598     the usual way.
599     .P
600     You can copy a file written by \fBpcretest\fP to a different host and reload it
601     there, even if the new host has opposite endianness to the one on which the
602     pattern was compiled. For example, you can compile on an i86 machine and run on
603     a SPARC machine.
604     .P
605     File names for saving and reloading can be absolute or relative, but note that
606     the shell facility of expanding a file name that starts with a tilde (~) is not
607     available.
608     .P
609     The ability to save and reload files in \fBpcretest\fP is intended for testing
610     and experimentation. It is not intended for production use because only a
611     single pattern can be written to a file. Furthermore, there is no facility for
612     supplying custom character tables for use with a reloaded pattern. If the
613     original pattern was compiled with custom tables, an attempt to match a subject
614     string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
615     Finally, if you attempt to load a file that is not in the correct format, the
616     result is undefined.
617     .
618     .
619 nigel 53 .SH AUTHOR
620 nigel 63 .rs
621     .sp
622 nigel 77 Philip Hazel
623 nigel 53 .br
624     University Computing Service,
625     .br
626     Cambridge CB2 3QG, England.
627 nigel 75 .P
628 nigel 63 .in 0
629 nigel 91 Last updated: 29 June 2006
630 nigel 53 .br
631 nigel 87 Copyright (c) 1997-2006 University of Cambridge.

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