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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 ph10 149 \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     \fB/<anycrlf>\fP PCRE_NEWLINE_ANY
172     \fB/<any>\fP PCRE_NEWLINE_ANY
173 nigel 75 .sp
174 nigel 93 Those specifying line ending sequencess are literal strings as shown. This
175     example sets multiline matching with CRLF as the line ending sequence:
176     .sp
177     /^abc/m<crlf>
178     .sp
179     Details of the meanings of these PCRE options are given in the
180 nigel 91 .\" HREF
181     \fBpcreapi\fP
182     .\"
183     documentation.
184     .
185     .
186     .SS "Finding all matches in a string"
187     .rs
188     .sp
189 nigel 53 Searching for all possible matches within each subject string can be requested
190 nigel 75 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
191 nigel 53 again to search the remainder of the subject string. The difference between
192 nigel 75 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
193     \fBpcre_exec()\fP to start searching at a new point within the entire string
194 nigel 53 (which is in effect what Perl does), whereas the latter passes over a shortened
195     substring. This makes a difference to the matching process if the pattern
196 nigel 75 begins with a lookbehind assertion (including \eb or \eB).
197     .P
198     If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
199 nigel 53 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
200     flags set in order to search for another, non-empty, match at the same point.
201     If this second match fails, the start offset is advanced by one, and the normal
202     match is retried. This imitates the way Perl handles such cases when using the
203 nigel 75 \fB/g\fP modifier or the \fBsplit()\fP function.
204 nigel 91 .
205     .
206     .SS "Other modifiers"
207     .rs
208     .sp
209 nigel 75 There are yet more modifiers for controlling the way \fBpcretest\fP
210 nigel 53 operates.
211 nigel 75 .P
212     The \fB/+\fP modifier requests that as well as outputting the substring that
213 nigel 53 matched the entire pattern, pcretest should in addition output the remainder of
214     the subject string. This is useful for tests where the subject contains
215     multiple copies of the same substring.
216 nigel 75 .P
217 nigel 93 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
218 ph10 123 output a representation of the compiled byte code after compilation. Normally
219 ph10 116 this information contains length and offset values; however, if \fB/Z\fP is
220     also present, this data is replaced by spaces. This is a special feature for
221     use in the automatic test scripts; it ensures that the same output is generated
222     for different internal link sizes.
223 nigel 93 .P
224 nigel 75 The \fB/L\fP modifier must be followed directly by the name of a locale, for
225 nigel 53 example,
226 nigel 75 .sp
227     /pattern/Lfr_FR
228     .sp
229     For this reason, it must be the last modifier. The given locale is set,
230     \fBpcre_maketables()\fP is called to build a set of character tables for the
231     locale, and this is then passed to \fBpcre_compile()\fP when compiling the
232     regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
233     pointer; that is, \fB/L\fP applies only to the expression on which it appears.
234     .P
235     The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
236     compiled pattern (whether it is anchored, has a fixed first character, and
237     so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
238     pattern. If the pattern is studied, the results of that are also output.
239     .P
240 nigel 93 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
241 ph10 148 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
242 nigel 75 .P
243     The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
244     fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
245     facility is for testing the feature in PCRE that allows it to execute patterns
246     that were compiled on a host with a different endianness. This feature is not
247     available when the POSIX interface to PCRE is being used, that is, when the
248     \fB/P\fP pattern modifier is specified. See also the section about saving and
249     reloading compiled patterns below.
250     .P
251     The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
252 nigel 53 expression has been compiled, and the results used when the expression is
253     matched.
254 nigel 75 .P
255     The \fB/M\fP modifier causes the size of memory block used to hold the compiled
256 nigel 53 pattern to be output.
257 nigel 75 .P
258     The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
259 nigel 53 API rather than its native API. When this is done, all other modifiers except
260 nigel 75 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
261     present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
262 nigel 53 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
263 nigel 75 .P
264     The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
265 nigel 63 option set. This turns on support for UTF-8 character handling in PCRE,
266     provided that it was compiled with this support enabled. This modifier also
267     causes any non-printing characters in output strings to be printed using the
268 nigel 75 \ex{hh...} notation if they are valid UTF-8 sequences.
269     .P
270     If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
271     call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
272 nigel 71 checking of the string for UTF-8 validity.
273 nigel 75 .
274     .
275     .SH "DATA LINES"
276 nigel 63 .rs
277     .sp
278 nigel 75 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
279     whitespace is removed, and it is then scanned for \e escapes. Some of these are
280 nigel 63 pretty esoteric features, intended for checking out some of the more
281     complicated features of PCRE. If you are just testing "ordinary" regular
282     expressions, you probably don't need any of these. The following escapes are
283 nigel 53 recognized:
284 nigel 75 .sp
285 nigel 93 \ea alarm (BEL, \ex07)
286     \eb backspace (\ex08)
287     \ee escape (\ex27)
288     \ef formfeed (\ex0c)
289     \en newline (\ex0a)
290 nigel 91 .\" JOIN
291     \eqdd set the PCRE_MATCH_LIMIT limit to dd
292     (any number of digits)
293 nigel 93 \er carriage return (\ex0d)
294     \et tab (\ex09)
295     \ev vertical tab (\ex0b)
296 nigel 75 \ennn octal character (up to 3 octal digits)
297     \exhh hexadecimal character (up to 2 hex digits)
298     .\" JOIN
299     \ex{hh...} hexadecimal character, any number of digits
300 nigel 63 in UTF-8 mode
301 nigel 91 .\" JOIN
302 nigel 75 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
303 nigel 91 or \fBpcre_dfa_exec()\fP
304     .\" JOIN
305 nigel 75 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
306 nigel 91 or \fBpcre_dfa_exec()\fP
307 nigel 75 .\" JOIN
308     \eCdd call pcre_copy_substring() for substring dd
309     after a successful match (number less than 32)
310     .\" JOIN
311     \eCname call pcre_copy_named_substring() for substring
312 nigel 63 "name" after a successful match (name termin-
313     ated by next non alphanumeric character)
314 nigel 75 .\" JOIN
315     \eC+ show the current captured substrings at callout
316 nigel 63 time
317 nigel 75 \eC- do not supply a callout function
318     .\" JOIN
319     \eC!n return 1 instead of 0 when callout number n is
320 nigel 63 reached
321 nigel 75 .\" JOIN
322     \eC!n!m return 1 instead of 0 when callout number n is
323 nigel 63 reached for the nth time
324 nigel 75 .\" JOIN
325     \eC*n pass the number n (may be negative) as callout
326     data; this is used as the callout return value
327 nigel 77 \eD use the \fBpcre_dfa_exec()\fP match function
328     \eF only shortest match for \fBpcre_dfa_exec()\fP
329 nigel 75 .\" JOIN
330     \eGdd call pcre_get_substring() for substring dd
331     after a successful match (number less than 32)
332     .\" JOIN
333     \eGname call pcre_get_named_substring() for substring
334 nigel 63 "name" after a successful match (name termin-
335     ated by next non-alphanumeric character)
336 nigel 75 .\" JOIN
337     \eL call pcre_get_substringlist() after a
338 nigel 63 successful match
339 nigel 91 .\" JOIN
340 nigel 87 \eM discover the minimum MATCH_LIMIT and
341     MATCH_LIMIT_RECURSION settings
342 nigel 91 .\" JOIN
343 nigel 75 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
344 nigel 91 or \fBpcre_dfa_exec()\fP
345 nigel 75 .\" JOIN
346     \eOdd set the size of the output vector passed to
347     \fBpcre_exec()\fP to dd (any number of digits)
348 nigel 77 .\" JOIN
349 nigel 75 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
350 nigel 77 or \fBpcre_dfa_exec()\fP
351 nigel 91 .\" JOIN
352     \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
353     (any number of digits)
354 nigel 77 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
355 nigel 75 \eS output details of memory get/free calls during matching
356 nigel 91 .\" JOIN
357 nigel 75 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
358 nigel 91 or \fBpcre_dfa_exec()\fP
359 nigel 75 .\" JOIN
360     \e? pass the PCRE_NO_UTF8_CHECK option to
361 nigel 91 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
362 nigel 75 \e>dd start the match at offset dd (any number of digits);
363 nigel 91 .\" JOIN
364 nigel 75 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
365 nigel 91 or \fBpcre_dfa_exec()\fP
366     .\" JOIN
367     \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
368     or \fBpcre_dfa_exec()\fP
369     .\" JOIN
370     \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
371     or \fBpcre_dfa_exec()\fP
372     .\" JOIN
373     \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
374     or \fBpcre_dfa_exec()\fP
375 nigel 93 .\" JOIN
376 ph10 149 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
377     or \fBpcre_dfa_exec()\fP
378     .\" JOIN
379 nigel 93 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
380     or \fBpcre_dfa_exec()\fP
381 nigel 75 .sp
382 nigel 93 The escapes that specify line ending sequences are literal strings, exactly as
383     shown. No more than one newline setting should be present in any data line.
384 nigel 75 .P
385 nigel 93 A backslash followed by anything else just escapes the anything else. If
386     the very last character is a backslash, it is ignored. This gives a way of
387     passing an empty line as data, since a real empty line terminates the data
388     input.
389     .P
390 nigel 75 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
391 nigel 87 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
392     fields of the \fBpcre_extra\fP data structure, until it finds the minimum
393     numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
394     \fImatch_limit\fP number is a measure of the amount of backtracking that takes
395     place, and checking it out can be instructive. For most simple matches, the
396     number is quite small, but for patterns with very large numbers of matching
397     possibilities, it can become large very quickly with increasing length of
398     subject string. The \fImatch_limit_recursion\fP number is a measure of how much
399     stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
400     to complete the match attempt.
401 nigel 75 .P
402     When \eO is used, the value specified may be higher or lower than the size set
403     by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
404     the call of \fBpcre_exec()\fP for the line in which it appears.
405     .P
406     If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
407 nigel 87 API to be used, the only option-setting sequences that have any effect are \eB
408     and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
409     \fBregexec()\fP.
410 nigel 75 .P
411     The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
412     of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
413 nigel 53 any number of hexadecimal digits inside the braces. The result is from one to
414     six bytes, encoded according to the UTF-8 rules.
415 nigel 75 .
416     .
417 nigel 77 .SH "THE ALTERNATIVE MATCHING FUNCTION"
418 nigel 63 .rs
419     .sp
420 nigel 77 By default, \fBpcretest\fP uses the standard PCRE matching function,
421     \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
422     alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
423     different way, and has some restrictions. The differences between the two
424     functions are described in the
425     .\" HREF
426     \fBpcrematching\fP
427     .\"
428     documentation.
429     .P
430     If a data line contains the \eD escape sequence, or if the command line
431     contains the \fB-dfa\fP option, the alternative matching function is called.
432     This function finds all possible matches at a given point. If, however, the \eF
433     escape sequence is present in the data line, it stops after the first match is
434     found. This is always the shortest possible match.
435     .
436     .
437     .SH "DEFAULT OUTPUT FROM PCRETEST"
438     .rs
439     .sp
440     This section describes the output when the normal matching function,
441     \fBpcre_exec()\fP, is being used.
442     .P
443 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
444 nigel 75 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
445     the whole pattern. Otherwise, it outputs "No match" or "Partial match"
446     when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
447     respectively, and otherwise the PCRE negative error number. Here is an example
448 nigel 77 of an interactive \fBpcretest\fP run.
449 nigel 75 .sp
450 nigel 53 $ pcretest
451 nigel 93 PCRE version 7.0 30-Nov-2006
452 nigel 75 .sp
453     re> /^abc(\ed+)/
454 nigel 53 data> abc123
455     0: abc123
456     1: 123
457     data> xyz
458     No match
459 nigel 75 .sp
460     If the strings contain any non-printing characters, they are output as \e0x
461     escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
462 nigel 93 pattern. See below for the definition of non-printing characters. If the
463     pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
464     the the rest of the subject string, identified by "0+" like this:
465 nigel 75 .sp
466 nigel 53 re> /cat/+
467     data> cataract
468     0: cat
469     0+ aract
470 nigel 75 .sp
471     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
472 nigel 53 matching attempts are output in sequence, like this:
473 nigel 75 .sp
474     re> /\eBi(\ew\ew)/g
475 nigel 53 data> Mississippi
476     0: iss
477     1: ss
478     0: iss
479     1: ss
480     0: ipp
481     1: pp
482 nigel 75 .sp
483 nigel 53 "No match" is output only if the first match attempt fails.
484 nigel 75 .P
485     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
486 nigel 53 data line that is successfully matched, the substrings extracted by the
487     convenience functions are output with C, G, or L after the string number
488     instead of a colon. This is in addition to the normal full list. The string
489     length (that is, the return from the extraction function) is given in
490 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
491     .P
492 nigel 93 Note that whereas patterns can be continued over several lines (a plain ">"
493 nigel 53 prompt is used for continuations), data lines may not. However newlines can be
494 nigel 93 included in data by means of the \en escape (or \er, \er\en, etc., depending on
495     the newline sequence setting).
496 nigel 75 .
497     .
498 nigel 93 .
499 nigel 77 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
500     .rs
501     .sp
502     When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
503     means of the \eD escape sequence or the \fB-dfa\fP command line option), the
504     output consists of a list of all the matches that start at the first point in
505     the subject where there is at least one match. For example:
506     .sp
507     re> /(tang|tangerine|tan)/
508     data> yellow tangerine\eD
509     0: tangerine
510     1: tang
511     2: tan
512     .sp
513     (Using the normal matching function on this data finds only "tang".) The
514     longest matching string is always given first (and numbered zero).
515     .P
516 nigel 93 If \fB/g\fP is present on the pattern, the search for further matches resumes
517 nigel 77 at the end of the longest match. For example:
518     .sp
519     re> /(tang|tangerine|tan)/g
520     data> yellow tangerine and tangy sultana\eD
521     0: tangerine
522     1: tang
523     2: tan
524     0: tang
525     1: tan
526     0: tan
527     .sp
528     Since the matching function does not support substring capture, the escape
529     sequences that are concerned with captured substrings are not relevant.
530     .
531     .
532     .SH "RESTARTING AFTER A PARTIAL MATCH"
533     .rs
534     .sp
535     When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
536     indicating that the subject partially matched the pattern, you can restart the
537     match with additional subject data by means of the \eR escape sequence. For
538     example:
539     .sp
540     re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
541     data> 23ja\eP\eD
542     Partial match: 23ja
543     data> n05\eR\eD
544     0: n05
545     .sp
546     For further information about partial matching, see the
547     .\" HREF
548     \fBpcrepartial\fP
549     .\"
550     documentation.
551     .
552     .
553 nigel 75 .SH CALLOUTS
554     .rs
555     .sp
556     If the pattern contains any callout requests, \fBpcretest\fP's callout function
557 nigel 77 is called during matching. This works with both matching functions. By default,
558     the called function displays the callout number, the start and current
559     positions in the text at the callout time, and the next pattern item to be
560     tested. For example, the output
561 nigel 75 .sp
562     --->pqrabcdef
563     0 ^ ^ \ed
564     .sp
565     indicates that callout number 0 occurred for a match attempt starting at the
566     fourth character of the subject string, when the pointer was at the seventh
567     character of the data, and when the next pattern item was \ed. Just one
568     circumflex is output if the start and current positions are the same.
569     .P
570     Callouts numbered 255 are assumed to be automatic callouts, inserted as a
571     result of the \fB/C\fP pattern modifier. In this case, instead of showing the
572     callout number, the offset in the pattern, preceded by a plus, is output. For
573     example:
574     .sp
575     re> /\ed?[A-E]\e*/C
576     data> E*
577     --->E*
578     +0 ^ \ed?
579     +3 ^ [A-E]
580     +8 ^^ \e*
581     +10 ^ ^
582     0: E*
583     .sp
584     The callout function in \fBpcretest\fP returns zero (carry on matching) by
585 nigel 77 default, but you can use a \eC item in a data line (as described above) to
586 nigel 75 change this.
587     .P
588     Inserting callouts can be helpful when using \fBpcretest\fP to check
589     complicated regular expressions. For further information about callouts, see
590     the
591     .\" HREF
592     \fBpcrecallout\fP
593     .\"
594     documentation.
595     .
596     .
597 nigel 93 .
598     .SH "NON-PRINTING CHARACTERS"
599     .rs
600     .sp
601     When \fBpcretest\fP is outputting text in the compiled version of a pattern,
602     bytes other than 32-126 are always treated as non-printing characters are are
603     therefore shown as hex escapes.
604     .P
605     When \fBpcretest\fP is outputting text that is a matched part of a subject
606     string, it behaves in the same way, unless a different locale has been set for
607     the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
608     function to distinguish printing and non-printing characters.
609     .
610     .
611     .
612 nigel 75 .SH "SAVING AND RELOADING COMPILED PATTERNS"
613     .rs
614     .sp
615     The facilities described in this section are not available when the POSIX
616     inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
617     specified.
618     .P
619     When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
620     compiled pattern to a file, by following the modifiers with > and a file name.
621     For example:
622     .sp
623     /pattern/im >/some/file
624     .sp
625     See the
626     .\" HREF
627     \fBpcreprecompile\fP
628     .\"
629     documentation for a discussion about saving and re-using compiled patterns.
630     .P
631     The data that is written is binary. The first eight bytes are the length of the
632     compiled pattern data followed by the length of the optional study data, each
633     written as four bytes in big-endian order (most significant byte first). If
634     there is no study data (either the pattern was not studied, or studying did not
635     return any data), the second length is zero. The lengths are followed by an
636     exact copy of the compiled pattern. If there is additional study data, this
637     follows immediately after the compiled pattern. After writing the file,
638     \fBpcretest\fP expects to read a new pattern.
639     .P
640     A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
641     name instead of a pattern. The name of the file must not contain a < character,
642     as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
643     characters.
644     For example:
645     .sp
646     re> </some/file
647     Compiled regex loaded from /some/file
648     No study data
649     .sp
650     When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
651     the usual way.
652     .P
653     You can copy a file written by \fBpcretest\fP to a different host and reload it
654     there, even if the new host has opposite endianness to the one on which the
655     pattern was compiled. For example, you can compile on an i86 machine and run on
656     a SPARC machine.
657     .P
658     File names for saving and reloading can be absolute or relative, but note that
659     the shell facility of expanding a file name that starts with a tilde (~) is not
660     available.
661     .P
662     The ability to save and reload files in \fBpcretest\fP is intended for testing
663     and experimentation. It is not intended for production use because only a
664     single pattern can be written to a file. Furthermore, there is no facility for
665     supplying custom character tables for use with a reloaded pattern. If the
666     original pattern was compiled with custom tables, an attempt to match a subject
667     string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
668     Finally, if you attempt to load a file that is not in the correct format, the
669     result is undefined.
670     .
671     .
672 nigel 93 .SH "SEE ALSO"
673     .rs
674     .sp
675     \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
676 ph10 148 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
677 nigel 93 .
678     .
679 nigel 53 .SH AUTHOR
680 nigel 63 .rs
681     .sp
682 ph10 99 .nf
683 nigel 77 Philip Hazel
684 ph10 99 University Computing Service
685 nigel 93 Cambridge CB2 3QH, England.
686 ph10 99 .fi
687     .
688     .
689     .SH REVISION
690     .rs
691     .sp
692     .nf
693 ph10 149 Last updated: 16 April 2007
694 ph10 99 Copyright (c) 1997-2007 University of Cambridge.
695     .fi

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