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Wed Aug 26 15:38:32 2009 UTC (5 years, 2 months ago) by ph10
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Remove restrictions on pcre_exec() partial matching.

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 ph10 386 \fB-M\fP
53     Behave as if each data line contains the \eM escape sequence; this causes
54 ph10 392 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
55 ph10 386 calling \fBpcre_exec()\fP repeatedly with different limits.
56     .TP 10
57 nigel 75 \fB-m\fP
58 nigel 53 Output the size of each compiled pattern after it has been compiled. This is
59 nigel 75 equivalent to adding \fB/M\fP to each regular expression. For compatibility
60     with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
61 nigel 53 .TP 10
62 nigel 75 \fB-o\fP \fIosize\fP
63     Set the number of elements in the output vector that is used when calling
64 nigel 93 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
65     is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
66     22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
67     changed for individual matching calls by including \eO in the data line (see
68     below).
69 nigel 53 .TP 10
70 nigel 75 \fB-p\fP
71 nigel 77 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
72     used to call PCRE. None of the other options has any effect when \fB-p\fP is
73     set.
74 nigel 53 .TP 10
75 nigel 91 \fB-q\fP
76 nigel 87 Do not output the version number of \fBpcretest\fP at the start of execution.
77     .TP 10
78 nigel 91 \fB-S\fP \fIsize\fP
79     On Unix-like systems, set the size of the runtime stack to \fIsize\fP
80     megabytes.
81     .TP 10
82 nigel 75 \fB-t\fP
83 nigel 63 Run each compile, study, and match many times with a timer, and output
84 nigel 75 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
85     \fB-t\fP, because you will then get the size output a zillion times, and the
86 nigel 93 timing will be distorted. You can control the number of iterations that are
87     used for timing by following \fB-t\fP with a number (as a separate item on the
88     command line). For example, "-t 1000" would iterate 1000 times. The default is
89     to iterate 500000 times.
90     .TP 10
91     \fB-tm\fP
92     This is like \fB-t\fP except that it times only the matching phase, not the
93     compile or study phases.
94 nigel 75 .
95     .
96 nigel 53 .SH DESCRIPTION
97 nigel 63 .rs
98     .sp
99 nigel 75 If \fBpcretest\fP is given two filename arguments, it reads from the first and
100 nigel 53 writes to the second. If it is given only one filename argument, it reads from
101     that file and writes to stdout. Otherwise, it reads from stdin and writes to
102     stdout, and prompts for each line of input, using "re>" to prompt for regular
103     expressions, and "data>" to prompt for data lines.
104 nigel 75 .P
105 ph10 289 When \fBpcretest\fP is built, a configuration option can specify that it should
106 ph10 287 be linked with the \fBlibreadline\fP library. When this is done, if the input
107     is from a terminal, it is read using the \fBreadline()\fP function. This
108     provides line-editing and history facilities. The output from the \fB-help\fP
109     option states whether or not \fBreadline()\fP will be used.
110     .P
111 nigel 53 The program handles any number of sets of input on a single input file. Each
112     set starts with a regular expression, and continues with any number of data
113 nigel 63 lines to be matched against the pattern.
114 nigel 75 .P
115     Each data line is matched separately and independently. If you want to do
116 nigel 91 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
117 nigel 93 etc., depending on the newline setting) in a single line of input to encode the
118     newline sequences. There is no limit on the length of data lines; the input
119 nigel 91 buffer is automatically extended if it is too small.
120 nigel 75 .P
121 nigel 63 An empty line signals the end of the data lines, at which point a new regular
122     expression is read. The regular expressions are given enclosed in any
123 nigel 91 non-alphanumeric delimiters other than backslash, for example:
124 nigel 75 .sp
125 nigel 53 /(a|bc)x+yz/
126 nigel 75 .sp
127 nigel 53 White space before the initial delimiter is ignored. A regular expression may
128     be continued over several input lines, in which case the newline characters are
129     included within it. It is possible to include the delimiter within the pattern
130     by escaping it, for example
131 nigel 75 .sp
132     /abc\e/def/
133     .sp
134 nigel 53 If you do so, the escape and the delimiter form part of the pattern, but since
135 nigel 75 delimiters are always non-alphanumeric, this does not affect its interpretation.
136 nigel 53 If the terminating delimiter is immediately followed by a backslash, for
137     example,
138 nigel 75 .sp
139     /abc/\e
140     .sp
141 nigel 53 then a backslash is added to the end of the pattern. This is done to provide a
142     way of testing the error condition that arises if a pattern finishes with a
143     backslash, because
144 nigel 75 .sp
145     /abc\e/
146     .sp
147 nigel 53 is interpreted as the first line of a pattern that starts with "abc/", causing
148     pcretest to read the next line as a continuation of the regular expression.
149 nigel 75 .
150     .
151     .SH "PATTERN MODIFIERS"
152 nigel 63 .rs
153     .sp
154 nigel 75 A pattern may be followed by any number of modifiers, which are mostly single
155     characters. Following Perl usage, these are referred to below as, for example,
156     "the \fB/i\fP modifier", even though the delimiter of the pattern need not
157     always be a slash, and no slash is used when writing modifiers. Whitespace may
158     appear between the final pattern delimiter and the first modifier, and between
159     the modifiers themselves.
160     .P
161     The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
162     PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
163     \fBpcre_compile()\fP is called. These four modifier letters have the same
164     effect as they do in Perl. For example:
165     .sp
166 nigel 53 /caseless/i
167 nigel 75 .sp
168     The following table shows additional modifiers for setting PCRE options that do
169     not correspond to anything in Perl:
170     .sp
171 ph10 231 \fB/A\fP PCRE_ANCHORED
172     \fB/C\fP PCRE_AUTO_CALLOUT
173     \fB/E\fP PCRE_DOLLAR_ENDONLY
174     \fB/f\fP PCRE_FIRSTLINE
175     \fB/J\fP PCRE_DUPNAMES
176     \fB/N\fP PCRE_NO_AUTO_CAPTURE
177     \fB/U\fP PCRE_UNGREEDY
178     \fB/X\fP PCRE_EXTRA
179 ph10 345 \fB/<JS>\fP PCRE_JAVASCRIPT_COMPAT
180 ph10 231 \fB/<cr>\fP PCRE_NEWLINE_CR
181     \fB/<lf>\fP PCRE_NEWLINE_LF
182     \fB/<crlf>\fP PCRE_NEWLINE_CRLF
183     \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
184     \fB/<any>\fP PCRE_NEWLINE_ANY
185     \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
186     \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
187 nigel 75 .sp
188 ph10 227 Those specifying line ending sequences are literal strings as shown, but the
189     letters can be in either case. This example sets multiline matching with CRLF
190     as the line ending sequence:
191 nigel 93 .sp
192     /^abc/m<crlf>
193     .sp
194     Details of the meanings of these PCRE options are given in the
195 nigel 91 .\" HREF
196     \fBpcreapi\fP
197     .\"
198     documentation.
199     .
200     .
201     .SS "Finding all matches in a string"
202     .rs
203     .sp
204 nigel 53 Searching for all possible matches within each subject string can be requested
205 nigel 75 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
206 nigel 53 again to search the remainder of the subject string. The difference between
207 nigel 75 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
208     \fBpcre_exec()\fP to start searching at a new point within the entire string
209 nigel 53 (which is in effect what Perl does), whereas the latter passes over a shortened
210     substring. This makes a difference to the matching process if the pattern
211 nigel 75 begins with a lookbehind assertion (including \eb or \eB).
212     .P
213     If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
214 nigel 53 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
215     flags set in order to search for another, non-empty, match at the same point.
216     If this second match fails, the start offset is advanced by one, and the normal
217     match is retried. This imitates the way Perl handles such cases when using the
218 nigel 75 \fB/g\fP modifier or the \fBsplit()\fP function.
219 nigel 91 .
220     .
221     .SS "Other modifiers"
222     .rs
223     .sp
224 nigel 75 There are yet more modifiers for controlling the way \fBpcretest\fP
225 nigel 53 operates.
226 nigel 75 .P
227     The \fB/+\fP modifier requests that as well as outputting the substring that
228 nigel 53 matched the entire pattern, pcretest should in addition output the remainder of
229     the subject string. This is useful for tests where the subject contains
230     multiple copies of the same substring.
231 nigel 75 .P
232 nigel 93 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
233 ph10 123 output a representation of the compiled byte code after compilation. Normally
234 ph10 116 this information contains length and offset values; however, if \fB/Z\fP is
235     also present, this data is replaced by spaces. This is a special feature for
236     use in the automatic test scripts; it ensures that the same output is generated
237     for different internal link sizes.
238 nigel 93 .P
239 nigel 75 The \fB/L\fP modifier must be followed directly by the name of a locale, for
240 nigel 53 example,
241 nigel 75 .sp
242     /pattern/Lfr_FR
243     .sp
244     For this reason, it must be the last modifier. The given locale is set,
245     \fBpcre_maketables()\fP is called to build a set of character tables for the
246     locale, and this is then passed to \fBpcre_compile()\fP when compiling the
247     regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
248     pointer; that is, \fB/L\fP applies only to the expression on which it appears.
249     .P
250     The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
251     compiled pattern (whether it is anchored, has a fixed first character, and
252     so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
253     pattern. If the pattern is studied, the results of that are also output.
254     .P
255 nigel 93 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
256 ph10 148 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
257 nigel 75 .P
258     The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
259     fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
260     facility is for testing the feature in PCRE that allows it to execute patterns
261     that were compiled on a host with a different endianness. This feature is not
262     available when the POSIX interface to PCRE is being used, that is, when the
263     \fB/P\fP pattern modifier is specified. See also the section about saving and
264     reloading compiled patterns below.
265     .P
266     The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
267 nigel 53 expression has been compiled, and the results used when the expression is
268     matched.
269 nigel 75 .P
270     The \fB/M\fP modifier causes the size of memory block used to hold the compiled
271 nigel 53 pattern to be output.
272 nigel 75 .P
273     The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
274 nigel 53 API rather than its native API. When this is done, all other modifiers except
275 nigel 75 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
276     present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
277 nigel 53 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
278 nigel 75 .P
279     The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
280 nigel 63 option set. This turns on support for UTF-8 character handling in PCRE,
281     provided that it was compiled with this support enabled. This modifier also
282     causes any non-printing characters in output strings to be printed using the
283 nigel 75 \ex{hh...} notation if they are valid UTF-8 sequences.
284     .P
285     If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
286     call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
287 nigel 71 checking of the string for UTF-8 validity.
288 nigel 75 .
289     .
290     .SH "DATA LINES"
291 nigel 63 .rs
292     .sp
293 nigel 75 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
294     whitespace is removed, and it is then scanned for \e escapes. Some of these are
295 nigel 63 pretty esoteric features, intended for checking out some of the more
296     complicated features of PCRE. If you are just testing "ordinary" regular
297     expressions, you probably don't need any of these. The following escapes are
298 nigel 53 recognized:
299 nigel 75 .sp
300 nigel 93 \ea alarm (BEL, \ex07)
301     \eb backspace (\ex08)
302     \ee escape (\ex27)
303     \ef formfeed (\ex0c)
304     \en newline (\ex0a)
305 nigel 91 .\" JOIN
306     \eqdd set the PCRE_MATCH_LIMIT limit to dd
307     (any number of digits)
308 nigel 93 \er carriage return (\ex0d)
309     \et tab (\ex09)
310     \ev vertical tab (\ex0b)
311 nigel 75 \ennn octal character (up to 3 octal digits)
312     \exhh hexadecimal character (up to 2 hex digits)
313     .\" JOIN
314     \ex{hh...} hexadecimal character, any number of digits
315 nigel 63 in UTF-8 mode
316 nigel 91 .\" JOIN
317 nigel 75 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
318 nigel 91 or \fBpcre_dfa_exec()\fP
319     .\" JOIN
320 nigel 75 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
321 nigel 91 or \fBpcre_dfa_exec()\fP
322 nigel 75 .\" JOIN
323     \eCdd call pcre_copy_substring() for substring dd
324     after a successful match (number less than 32)
325     .\" JOIN
326     \eCname call pcre_copy_named_substring() for substring
327 nigel 63 "name" after a successful match (name termin-
328     ated by next non alphanumeric character)
329 nigel 75 .\" JOIN
330     \eC+ show the current captured substrings at callout
331 nigel 63 time
332 nigel 75 \eC- do not supply a callout function
333     .\" JOIN
334     \eC!n return 1 instead of 0 when callout number n is
335 nigel 63 reached
336 nigel 75 .\" JOIN
337     \eC!n!m return 1 instead of 0 when callout number n is
338 nigel 63 reached for the nth time
339 nigel 75 .\" JOIN
340     \eC*n pass the number n (may be negative) as callout
341     data; this is used as the callout return value
342 nigel 77 \eD use the \fBpcre_dfa_exec()\fP match function
343     \eF only shortest match for \fBpcre_dfa_exec()\fP
344 nigel 75 .\" JOIN
345     \eGdd call pcre_get_substring() for substring dd
346     after a successful match (number less than 32)
347     .\" JOIN
348     \eGname call pcre_get_named_substring() for substring
349 nigel 63 "name" after a successful match (name termin-
350     ated by next non-alphanumeric character)
351 nigel 75 .\" JOIN
352     \eL call pcre_get_substringlist() after a
353 nigel 63 successful match
354 nigel 91 .\" JOIN
355 nigel 87 \eM discover the minimum MATCH_LIMIT and
356     MATCH_LIMIT_RECURSION settings
357 nigel 91 .\" JOIN
358 nigel 75 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
359 nigel 91 or \fBpcre_dfa_exec()\fP
360 nigel 75 .\" JOIN
361     \eOdd set the size of the output vector passed to
362     \fBpcre_exec()\fP to dd (any number of digits)
363 nigel 77 .\" JOIN
364 nigel 75 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
365 nigel 77 or \fBpcre_dfa_exec()\fP
366 nigel 91 .\" JOIN
367     \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
368     (any number of digits)
369 nigel 77 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
370 nigel 75 \eS output details of memory get/free calls during matching
371 nigel 91 .\" JOIN
372 nigel 75 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
373 nigel 91 or \fBpcre_dfa_exec()\fP
374 nigel 75 .\" JOIN
375     \e? pass the PCRE_NO_UTF8_CHECK option to
376 nigel 91 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
377 nigel 75 \e>dd start the match at offset dd (any number of digits);
378 nigel 91 .\" JOIN
379 nigel 75 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
380 nigel 91 or \fBpcre_dfa_exec()\fP
381     .\" JOIN
382     \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
383     or \fBpcre_dfa_exec()\fP
384     .\" JOIN
385     \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
386     or \fBpcre_dfa_exec()\fP
387     .\" JOIN
388     \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
389     or \fBpcre_dfa_exec()\fP
390 nigel 93 .\" JOIN
391 ph10 149 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
392     or \fBpcre_dfa_exec()\fP
393     .\" JOIN
394 nigel 93 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
395     or \fBpcre_dfa_exec()\fP
396 nigel 75 .sp
397 nigel 93 The escapes that specify line ending sequences are literal strings, exactly as
398     shown. No more than one newline setting should be present in any data line.
399 nigel 75 .P
400 nigel 93 A backslash followed by anything else just escapes the anything else. If
401     the very last character is a backslash, it is ignored. This gives a way of
402     passing an empty line as data, since a real empty line terminates the data
403     input.
404     .P
405 nigel 75 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
406 nigel 87 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
407     fields of the \fBpcre_extra\fP data structure, until it finds the minimum
408     numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
409     \fImatch_limit\fP number is a measure of the amount of backtracking that takes
410     place, and checking it out can be instructive. For most simple matches, the
411     number is quite small, but for patterns with very large numbers of matching
412     possibilities, it can become large very quickly with increasing length of
413     subject string. The \fImatch_limit_recursion\fP number is a measure of how much
414     stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
415     to complete the match attempt.
416 nigel 75 .P
417     When \eO is used, the value specified may be higher or lower than the size set
418     by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
419     the call of \fBpcre_exec()\fP for the line in which it appears.
420     .P
421     If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
422 nigel 87 API to be used, the only option-setting sequences that have any effect are \eB
423     and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
424     \fBregexec()\fP.
425 nigel 75 .P
426     The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
427     of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
428 nigel 53 any number of hexadecimal digits inside the braces. The result is from one to
429 ph10 211 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
430     allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
431     valid Unicode code points, or indeed valid UTF-8 characters according to the
432     later rules in RFC 3629.
433 nigel 75 .
434     .
435 nigel 77 .SH "THE ALTERNATIVE MATCHING FUNCTION"
436 nigel 63 .rs
437     .sp
438 nigel 77 By default, \fBpcretest\fP uses the standard PCRE matching function,
439     \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
440     alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
441     different way, and has some restrictions. The differences between the two
442     functions are described in the
443     .\" HREF
444     \fBpcrematching\fP
445     .\"
446     documentation.
447     .P
448     If a data line contains the \eD escape sequence, or if the command line
449     contains the \fB-dfa\fP option, the alternative matching function is called.
450     This function finds all possible matches at a given point. If, however, the \eF
451     escape sequence is present in the data line, it stops after the first match is
452     found. This is always the shortest possible match.
453     .
454     .
455     .SH "DEFAULT OUTPUT FROM PCRETEST"
456     .rs
457     .sp
458     This section describes the output when the normal matching function,
459     \fBpcre_exec()\fP, is being used.
460     .P
461 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
462 nigel 75 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
463 ph10 426 the whole pattern. Otherwise, it outputs "No match" or "Partial match" followed
464     by the partially matching substring when \fBpcre_exec()\fP returns
465     PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL, respectively, and otherwise the PCRE
466     negative error number. Here is an example of an interactive \fBpcretest\fP run.
467 nigel 75 .sp
468 nigel 53 $ pcretest
469 nigel 93 PCRE version 7.0 30-Nov-2006
470 nigel 75 .sp
471     re> /^abc(\ed+)/
472 nigel 53 data> abc123
473     0: abc123
474     1: 123
475     data> xyz
476     No match
477 nigel 75 .sp
478 ph10 286 Note that unset capturing substrings that are not followed by one that is set
479 ph10 273 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
480     the following example, there are two capturing substrings, but when the first
481 ph10 286 data line is matched, the second, unset substring is not shown. An "internal"
482 ph10 273 unset substring is shown as "<unset>", as for the second data line.
483     .sp
484     re> /(a)|(b)/
485     data> a
486     0: a
487     1: a
488     data> b
489     0: b
490     1: <unset>
491 ph10 286 2: b
492 ph10 273 .sp
493 nigel 75 If the strings contain any non-printing characters, they are output as \e0x
494     escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
495 nigel 93 pattern. See below for the definition of non-printing characters. If the
496     pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
497     the the rest of the subject string, identified by "0+" like this:
498 nigel 75 .sp
499 nigel 53 re> /cat/+
500     data> cataract
501     0: cat
502     0+ aract
503 nigel 75 .sp
504     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
505 nigel 53 matching attempts are output in sequence, like this:
506 nigel 75 .sp
507     re> /\eBi(\ew\ew)/g
508 nigel 53 data> Mississippi
509     0: iss
510     1: ss
511     0: iss
512     1: ss
513     0: ipp
514     1: pp
515 nigel 75 .sp
516 nigel 53 "No match" is output only if the first match attempt fails.
517 nigel 75 .P
518     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
519 nigel 53 data line that is successfully matched, the substrings extracted by the
520     convenience functions are output with C, G, or L after the string number
521     instead of a colon. This is in addition to the normal full list. The string
522     length (that is, the return from the extraction function) is given in
523 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
524     .P
525 nigel 93 Note that whereas patterns can be continued over several lines (a plain ">"
526 nigel 53 prompt is used for continuations), data lines may not. However newlines can be
527 nigel 93 included in data by means of the \en escape (or \er, \er\en, etc., depending on
528     the newline sequence setting).
529 nigel 75 .
530     .
531 nigel 93 .
532 nigel 77 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
533     .rs
534     .sp
535     When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
536     means of the \eD escape sequence or the \fB-dfa\fP command line option), the
537     output consists of a list of all the matches that start at the first point in
538     the subject where there is at least one match. For example:
539     .sp
540     re> /(tang|tangerine|tan)/
541     data> yellow tangerine\eD
542     0: tangerine
543     1: tang
544     2: tan
545     .sp
546     (Using the normal matching function on this data finds only "tang".) The
547     longest matching string is always given first (and numbered zero).
548     .P
549 nigel 93 If \fB/g\fP is present on the pattern, the search for further matches resumes
550 nigel 77 at the end of the longest match. For example:
551     .sp
552     re> /(tang|tangerine|tan)/g
553     data> yellow tangerine and tangy sultana\eD
554     0: tangerine
555     1: tang
556     2: tan
557     0: tang
558     1: tan
559     0: tan
560     .sp
561     Since the matching function does not support substring capture, the escape
562     sequences that are concerned with captured substrings are not relevant.
563     .
564     .
565     .SH "RESTARTING AFTER A PARTIAL MATCH"
566     .rs
567     .sp
568     When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
569     indicating that the subject partially matched the pattern, you can restart the
570     match with additional subject data by means of the \eR escape sequence. For
571     example:
572     .sp
573 ph10 155 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
574 nigel 77 data> 23ja\eP\eD
575     Partial match: 23ja
576     data> n05\eR\eD
577     0: n05
578     .sp
579     For further information about partial matching, see the
580     .\" HREF
581     \fBpcrepartial\fP
582     .\"
583     documentation.
584     .
585     .
586 nigel 75 .SH CALLOUTS
587     .rs
588     .sp
589     If the pattern contains any callout requests, \fBpcretest\fP's callout function
590 nigel 77 is called during matching. This works with both matching functions. By default,
591     the called function displays the callout number, the start and current
592     positions in the text at the callout time, and the next pattern item to be
593     tested. For example, the output
594 nigel 75 .sp
595     --->pqrabcdef
596     0 ^ ^ \ed
597     .sp
598     indicates that callout number 0 occurred for a match attempt starting at the
599     fourth character of the subject string, when the pointer was at the seventh
600     character of the data, and when the next pattern item was \ed. Just one
601     circumflex is output if the start and current positions are the same.
602     .P
603     Callouts numbered 255 are assumed to be automatic callouts, inserted as a
604     result of the \fB/C\fP pattern modifier. In this case, instead of showing the
605     callout number, the offset in the pattern, preceded by a plus, is output. For
606     example:
607     .sp
608     re> /\ed?[A-E]\e*/C
609     data> E*
610     --->E*
611     +0 ^ \ed?
612     +3 ^ [A-E]
613     +8 ^^ \e*
614     +10 ^ ^
615     0: E*
616     .sp
617     The callout function in \fBpcretest\fP returns zero (carry on matching) by
618 nigel 77 default, but you can use a \eC item in a data line (as described above) to
619 nigel 75 change this.
620     .P
621     Inserting callouts can be helpful when using \fBpcretest\fP to check
622     complicated regular expressions. For further information about callouts, see
623     the
624     .\" HREF
625     \fBpcrecallout\fP
626     .\"
627     documentation.
628     .
629     .
630 nigel 93 .
631     .SH "NON-PRINTING CHARACTERS"
632     .rs
633     .sp
634     When \fBpcretest\fP is outputting text in the compiled version of a pattern,
635     bytes other than 32-126 are always treated as non-printing characters are are
636     therefore shown as hex escapes.
637     .P
638     When \fBpcretest\fP is outputting text that is a matched part of a subject
639     string, it behaves in the same way, unless a different locale has been set for
640     the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
641     function to distinguish printing and non-printing characters.
642     .
643     .
644     .
645 nigel 75 .SH "SAVING AND RELOADING COMPILED PATTERNS"
646     .rs
647     .sp
648     The facilities described in this section are not available when the POSIX
649     inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
650     specified.
651     .P
652     When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
653     compiled pattern to a file, by following the modifiers with > and a file name.
654     For example:
655     .sp
656     /pattern/im >/some/file
657     .sp
658     See the
659     .\" HREF
660     \fBpcreprecompile\fP
661     .\"
662     documentation for a discussion about saving and re-using compiled patterns.
663     .P
664     The data that is written is binary. The first eight bytes are the length of the
665     compiled pattern data followed by the length of the optional study data, each
666     written as four bytes in big-endian order (most significant byte first). If
667     there is no study data (either the pattern was not studied, or studying did not
668     return any data), the second length is zero. The lengths are followed by an
669     exact copy of the compiled pattern. If there is additional study data, this
670     follows immediately after the compiled pattern. After writing the file,
671     \fBpcretest\fP expects to read a new pattern.
672     .P
673     A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
674     name instead of a pattern. The name of the file must not contain a < character,
675     as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
676     characters.
677     For example:
678     .sp
679     re> </some/file
680     Compiled regex loaded from /some/file
681     No study data
682     .sp
683     When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
684     the usual way.
685     .P
686     You can copy a file written by \fBpcretest\fP to a different host and reload it
687     there, even if the new host has opposite endianness to the one on which the
688     pattern was compiled. For example, you can compile on an i86 machine and run on
689     a SPARC machine.
690     .P
691     File names for saving and reloading can be absolute or relative, but note that
692     the shell facility of expanding a file name that starts with a tilde (~) is not
693     available.
694     .P
695     The ability to save and reload files in \fBpcretest\fP is intended for testing
696     and experimentation. It is not intended for production use because only a
697     single pattern can be written to a file. Furthermore, there is no facility for
698     supplying custom character tables for use with a reloaded pattern. If the
699     original pattern was compiled with custom tables, an attempt to match a subject
700     string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
701     Finally, if you attempt to load a file that is not in the correct format, the
702     result is undefined.
703     .
704     .
705 nigel 93 .SH "SEE ALSO"
706     .rs
707     .sp
708     \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
709 ph10 148 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
710 nigel 93 .
711     .
712 nigel 53 .SH AUTHOR
713 nigel 63 .rs
714     .sp
715 ph10 99 .nf
716 nigel 77 Philip Hazel
717 ph10 99 University Computing Service
718 nigel 93 Cambridge CB2 3QH, England.
719 ph10 99 .fi
720     .
721     .
722     .SH REVISION
723     .rs
724     .sp
725     .nf
726 ph10 426 Last updated: 25 August 2009
727 ph10 386 Copyright (c) 1997-2009 University of Cambridge.
728 ph10 99 .fi

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