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Revision 428 - (hide annotations) (download)
Mon Aug 31 17:10:26 2009 UTC (5 years, 2 months ago) by ph10
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Further partial match change: add PCRE_PARTIAL_HARD and make more intuitive.

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 ph10 428 \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP
365     or \fBpcre_dfa_exec()\fP; if used twice, pass the
366     PCRE_PARTIAL_HARD option
367 nigel 91 .\" JOIN
368     \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
369     (any number of digits)
370 nigel 77 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
371 nigel 75 \eS output details of memory get/free calls during matching
372 nigel 91 .\" JOIN
373 nigel 75 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
374 nigel 91 or \fBpcre_dfa_exec()\fP
375 nigel 75 .\" JOIN
376     \e? pass the PCRE_NO_UTF8_CHECK option to
377 nigel 91 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
378 nigel 75 \e>dd start the match at offset dd (any number of digits);
379 nigel 91 .\" JOIN
380 nigel 75 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
381 nigel 91 or \fBpcre_dfa_exec()\fP
382     .\" JOIN
383     \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
384     or \fBpcre_dfa_exec()\fP
385     .\" JOIN
386     \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
387     or \fBpcre_dfa_exec()\fP
388     .\" JOIN
389     \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
390     or \fBpcre_dfa_exec()\fP
391 nigel 93 .\" JOIN
392 ph10 149 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
393     or \fBpcre_dfa_exec()\fP
394     .\" JOIN
395 nigel 93 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
396     or \fBpcre_dfa_exec()\fP
397 nigel 75 .sp
398 nigel 93 The escapes that specify line ending sequences are literal strings, exactly as
399     shown. No more than one newline setting should be present in any data line.
400 nigel 75 .P
401 nigel 93 A backslash followed by anything else just escapes the anything else. If
402     the very last character is a backslash, it is ignored. This gives a way of
403     passing an empty line as data, since a real empty line terminates the data
404     input.
405     .P
406 nigel 75 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
407 nigel 87 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
408     fields of the \fBpcre_extra\fP data structure, until it finds the minimum
409     numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
410     \fImatch_limit\fP number is a measure of the amount of backtracking that takes
411     place, and checking it out can be instructive. For most simple matches, the
412     number is quite small, but for patterns with very large numbers of matching
413     possibilities, it can become large very quickly with increasing length of
414     subject string. The \fImatch_limit_recursion\fP number is a measure of how much
415     stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
416     to complete the match attempt.
417 nigel 75 .P
418     When \eO is used, the value specified may be higher or lower than the size set
419     by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
420     the call of \fBpcre_exec()\fP for the line in which it appears.
421     .P
422     If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
423 nigel 87 API to be used, the only option-setting sequences that have any effect are \eB
424     and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
425     \fBregexec()\fP.
426 nigel 75 .P
427     The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
428     of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
429 nigel 53 any number of hexadecimal digits inside the braces. The result is from one to
430 ph10 211 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
431     allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
432     valid Unicode code points, or indeed valid UTF-8 characters according to the
433     later rules in RFC 3629.
434 nigel 75 .
435     .
436 nigel 77 .SH "THE ALTERNATIVE MATCHING FUNCTION"
437 nigel 63 .rs
438     .sp
439 nigel 77 By default, \fBpcretest\fP uses the standard PCRE matching function,
440     \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
441     alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
442     different way, and has some restrictions. The differences between the two
443     functions are described in the
444     .\" HREF
445     \fBpcrematching\fP
446     .\"
447     documentation.
448     .P
449     If a data line contains the \eD escape sequence, or if the command line
450     contains the \fB-dfa\fP option, the alternative matching function is called.
451     This function finds all possible matches at a given point. If, however, the \eF
452     escape sequence is present in the data line, it stops after the first match is
453     found. This is always the shortest possible match.
454     .
455     .
456     .SH "DEFAULT OUTPUT FROM PCRETEST"
457     .rs
458     .sp
459     This section describes the output when the normal matching function,
460     \fBpcre_exec()\fP, is being used.
461     .P
462 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
463 nigel 75 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
464 ph10 428 the whole pattern. Otherwise, it outputs "No match" or "Partial match:"
465     followed by the partially matching substring when \fBpcre_exec()\fP returns
466 ph10 426 PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL, respectively, and otherwise the PCRE
467     negative error number. Here is an example of an interactive \fBpcretest\fP run.
468 nigel 75 .sp
469 nigel 53 $ pcretest
470 nigel 93 PCRE version 7.0 30-Nov-2006
471 nigel 75 .sp
472     re> /^abc(\ed+)/
473 nigel 53 data> abc123
474     0: abc123
475     1: 123
476     data> xyz
477     No match
478 nigel 75 .sp
479 ph10 286 Note that unset capturing substrings that are not followed by one that is set
480 ph10 273 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
481     the following example, there are two capturing substrings, but when the first
482 ph10 286 data line is matched, the second, unset substring is not shown. An "internal"
483 ph10 273 unset substring is shown as "<unset>", as for the second data line.
484     .sp
485     re> /(a)|(b)/
486     data> a
487     0: a
488     1: a
489     data> b
490     0: b
491     1: <unset>
492 ph10 286 2: b
493 ph10 273 .sp
494 nigel 75 If the strings contain any non-printing characters, they are output as \e0x
495     escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
496 nigel 93 pattern. See below for the definition of non-printing characters. If the
497     pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
498     the the rest of the subject string, identified by "0+" like this:
499 nigel 75 .sp
500 nigel 53 re> /cat/+
501     data> cataract
502     0: cat
503     0+ aract
504 nigel 75 .sp
505     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
506 nigel 53 matching attempts are output in sequence, like this:
507 nigel 75 .sp
508     re> /\eBi(\ew\ew)/g
509 nigel 53 data> Mississippi
510     0: iss
511     1: ss
512     0: iss
513     1: ss
514     0: ipp
515     1: pp
516 nigel 75 .sp
517 nigel 53 "No match" is output only if the first match attempt fails.
518 nigel 75 .P
519     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
520 nigel 53 data line that is successfully matched, the substrings extracted by the
521     convenience functions are output with C, G, or L after the string number
522     instead of a colon. This is in addition to the normal full list. The string
523     length (that is, the return from the extraction function) is given in
524 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
525     .P
526 nigel 93 Note that whereas patterns can be continued over several lines (a plain ">"
527 nigel 53 prompt is used for continuations), data lines may not. However newlines can be
528 nigel 93 included in data by means of the \en escape (or \er, \er\en, etc., depending on
529     the newline sequence setting).
530 nigel 75 .
531     .
532 nigel 93 .
533 nigel 77 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
534     .rs
535     .sp
536     When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
537     means of the \eD escape sequence or the \fB-dfa\fP command line option), the
538     output consists of a list of all the matches that start at the first point in
539     the subject where there is at least one match. For example:
540     .sp
541     re> /(tang|tangerine|tan)/
542     data> yellow tangerine\eD
543     0: tangerine
544     1: tang
545     2: tan
546     .sp
547     (Using the normal matching function on this data finds only "tang".) The
548 ph10 428 longest matching string is always given first (and numbered zero). After a
549     PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
550     partially matching substring.
551 nigel 77 .P
552 nigel 93 If \fB/g\fP is present on the pattern, the search for further matches resumes
553 nigel 77 at the end of the longest match. For example:
554     .sp
555     re> /(tang|tangerine|tan)/g
556     data> yellow tangerine and tangy sultana\eD
557     0: tangerine
558     1: tang
559     2: tan
560     0: tang
561     1: tan
562     0: tan
563     .sp
564     Since the matching function does not support substring capture, the escape
565     sequences that are concerned with captured substrings are not relevant.
566     .
567     .
568     .SH "RESTARTING AFTER A PARTIAL MATCH"
569     .rs
570     .sp
571     When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
572     indicating that the subject partially matched the pattern, you can restart the
573     match with additional subject data by means of the \eR escape sequence. For
574     example:
575     .sp
576 ph10 155 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
577 nigel 77 data> 23ja\eP\eD
578     Partial match: 23ja
579     data> n05\eR\eD
580     0: n05
581     .sp
582     For further information about partial matching, see the
583     .\" HREF
584     \fBpcrepartial\fP
585     .\"
586     documentation.
587     .
588     .
589 nigel 75 .SH CALLOUTS
590     .rs
591     .sp
592     If the pattern contains any callout requests, \fBpcretest\fP's callout function
593 nigel 77 is called during matching. This works with both matching functions. By default,
594     the called function displays the callout number, the start and current
595     positions in the text at the callout time, and the next pattern item to be
596     tested. For example, the output
597 nigel 75 .sp
598     --->pqrabcdef
599     0 ^ ^ \ed
600     .sp
601     indicates that callout number 0 occurred for a match attempt starting at the
602     fourth character of the subject string, when the pointer was at the seventh
603     character of the data, and when the next pattern item was \ed. Just one
604     circumflex is output if the start and current positions are the same.
605     .P
606     Callouts numbered 255 are assumed to be automatic callouts, inserted as a
607     result of the \fB/C\fP pattern modifier. In this case, instead of showing the
608     callout number, the offset in the pattern, preceded by a plus, is output. For
609     example:
610     .sp
611     re> /\ed?[A-E]\e*/C
612     data> E*
613     --->E*
614     +0 ^ \ed?
615     +3 ^ [A-E]
616     +8 ^^ \e*
617     +10 ^ ^
618     0: E*
619     .sp
620     The callout function in \fBpcretest\fP returns zero (carry on matching) by
621 nigel 77 default, but you can use a \eC item in a data line (as described above) to
622 nigel 75 change this.
623     .P
624     Inserting callouts can be helpful when using \fBpcretest\fP to check
625     complicated regular expressions. For further information about callouts, see
626     the
627     .\" HREF
628     \fBpcrecallout\fP
629     .\"
630     documentation.
631     .
632     .
633 nigel 93 .
634     .SH "NON-PRINTING CHARACTERS"
635     .rs
636     .sp
637     When \fBpcretest\fP is outputting text in the compiled version of a pattern,
638     bytes other than 32-126 are always treated as non-printing characters are are
639     therefore shown as hex escapes.
640     .P
641     When \fBpcretest\fP is outputting text that is a matched part of a subject
642     string, it behaves in the same way, unless a different locale has been set for
643     the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
644     function to distinguish printing and non-printing characters.
645     .
646     .
647     .
648 nigel 75 .SH "SAVING AND RELOADING COMPILED PATTERNS"
649     .rs
650     .sp
651     The facilities described in this section are not available when the POSIX
652     inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
653     specified.
654     .P
655     When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
656     compiled pattern to a file, by following the modifiers with > and a file name.
657     For example:
658     .sp
659     /pattern/im >/some/file
660     .sp
661     See the
662     .\" HREF
663     \fBpcreprecompile\fP
664     .\"
665     documentation for a discussion about saving and re-using compiled patterns.
666     .P
667     The data that is written is binary. The first eight bytes are the length of the
668     compiled pattern data followed by the length of the optional study data, each
669     written as four bytes in big-endian order (most significant byte first). If
670     there is no study data (either the pattern was not studied, or studying did not
671     return any data), the second length is zero. The lengths are followed by an
672     exact copy of the compiled pattern. If there is additional study data, this
673     follows immediately after the compiled pattern. After writing the file,
674     \fBpcretest\fP expects to read a new pattern.
675     .P
676     A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
677     name instead of a pattern. The name of the file must not contain a < character,
678     as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
679     characters.
680     For example:
681     .sp
682     re> </some/file
683     Compiled regex loaded from /some/file
684     No study data
685     .sp
686     When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
687     the usual way.
688     .P
689     You can copy a file written by \fBpcretest\fP to a different host and reload it
690     there, even if the new host has opposite endianness to the one on which the
691     pattern was compiled. For example, you can compile on an i86 machine and run on
692     a SPARC machine.
693     .P
694     File names for saving and reloading can be absolute or relative, but note that
695     the shell facility of expanding a file name that starts with a tilde (~) is not
696     available.
697     .P
698     The ability to save and reload files in \fBpcretest\fP is intended for testing
699     and experimentation. It is not intended for production use because only a
700     single pattern can be written to a file. Furthermore, there is no facility for
701     supplying custom character tables for use with a reloaded pattern. If the
702     original pattern was compiled with custom tables, an attempt to match a subject
703     string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
704     Finally, if you attempt to load a file that is not in the correct format, the
705     result is undefined.
706     .
707     .
708 nigel 93 .SH "SEE ALSO"
709     .rs
710     .sp
711     \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
712 ph10 148 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
713 nigel 93 .
714     .
715 nigel 53 .SH AUTHOR
716 nigel 63 .rs
717     .sp
718 ph10 99 .nf
719 nigel 77 Philip Hazel
720 ph10 99 University Computing Service
721 nigel 93 Cambridge CB2 3QH, England.
722 ph10 99 .fi
723     .
724     .
725     .SH REVISION
726     .rs
727     .sp
728     .nf
729 ph10 428 Last updated: 29 August 2009
730 ph10 386 Copyright (c) 1997-2009 University of Cambridge.
731 ph10 99 .fi

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