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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 ph10 289 When \fBpcretest\fP is built, a configuration option can specify that it should
101 ph10 287 be linked with the \fBlibreadline\fP library. When this is done, if the input
102     is from a terminal, it is read using the \fBreadline()\fP function. This
103     provides line-editing and history facilities. The output from the \fB-help\fP
104     option states whether or not \fBreadline()\fP will be used.
105     .P
106 nigel 53 The program handles any number of sets of input on a single input file. Each
107     set starts with a regular expression, and continues with any number of data
108 nigel 63 lines to be matched against the pattern.
109 nigel 75 .P
110     Each data line is matched separately and independently. If you want to do
111 nigel 91 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
112 nigel 93 etc., depending on the newline setting) in a single line of input to encode the
113     newline sequences. There is no limit on the length of data lines; the input
114 nigel 91 buffer is automatically extended if it is too small.
115 nigel 75 .P
116 nigel 63 An empty line signals the end of the data lines, at which point a new regular
117     expression is read. The regular expressions are given enclosed in any
118 nigel 91 non-alphanumeric delimiters other than backslash, for example:
119 nigel 75 .sp
120 nigel 53 /(a|bc)x+yz/
121 nigel 75 .sp
122 nigel 53 White space before the initial delimiter is ignored. A regular expression may
123     be continued over several input lines, in which case the newline characters are
124     included within it. It is possible to include the delimiter within the pattern
125     by escaping it, for example
126 nigel 75 .sp
127     /abc\e/def/
128     .sp
129 nigel 53 If you do so, the escape and the delimiter form part of the pattern, but since
130 nigel 75 delimiters are always non-alphanumeric, this does not affect its interpretation.
131 nigel 53 If the terminating delimiter is immediately followed by a backslash, for
132     example,
133 nigel 75 .sp
134     /abc/\e
135     .sp
136 nigel 53 then a backslash is added to the end of the pattern. This is done to provide a
137     way of testing the error condition that arises if a pattern finishes with a
138     backslash, because
139 nigel 75 .sp
140     /abc\e/
141     .sp
142 nigel 53 is interpreted as the first line of a pattern that starts with "abc/", causing
143     pcretest to read the next line as a continuation of the regular expression.
144 nigel 75 .
145     .
146     .SH "PATTERN MODIFIERS"
147 nigel 63 .rs
148     .sp
149 nigel 75 A pattern may be followed by any number of modifiers, which are mostly single
150     characters. Following Perl usage, these are referred to below as, for example,
151     "the \fB/i\fP modifier", even though the delimiter of the pattern need not
152     always be a slash, and no slash is used when writing modifiers. Whitespace may
153     appear between the final pattern delimiter and the first modifier, and between
154     the modifiers themselves.
155     .P
156     The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
157     PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
158     \fBpcre_compile()\fP is called. These four modifier letters have the same
159     effect as they do in Perl. For example:
160     .sp
161 nigel 53 /caseless/i
162 nigel 75 .sp
163     The following table shows additional modifiers for setting PCRE options that do
164     not correspond to anything in Perl:
165     .sp
166 ph10 231 \fB/A\fP PCRE_ANCHORED
167     \fB/C\fP PCRE_AUTO_CALLOUT
168     \fB/E\fP PCRE_DOLLAR_ENDONLY
169     \fB/f\fP PCRE_FIRSTLINE
170     \fB/J\fP PCRE_DUPNAMES
171     \fB/N\fP PCRE_NO_AUTO_CAPTURE
172     \fB/U\fP PCRE_UNGREEDY
173     \fB/X\fP PCRE_EXTRA
174 ph10 336 \fB/<JS>\fP PCRE_JAVASCRIPT_COMPAT
175 ph10 231 \fB/<cr>\fP PCRE_NEWLINE_CR
176     \fB/<lf>\fP PCRE_NEWLINE_LF
177     \fB/<crlf>\fP PCRE_NEWLINE_CRLF
178     \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
179     \fB/<any>\fP PCRE_NEWLINE_ANY
180     \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
181     \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
182 nigel 75 .sp
183 ph10 227 Those specifying line ending sequences are literal strings as shown, but the
184     letters can be in either case. This example sets multiline matching with CRLF
185     as the line ending sequence:
186 nigel 93 .sp
187     /^abc/m<crlf>
188     .sp
189     Details of the meanings of these PCRE options are given in the
190 nigel 91 .\" HREF
191     \fBpcreapi\fP
192     .\"
193     documentation.
194     .
195     .
196     .SS "Finding all matches in a string"
197     .rs
198     .sp
199 nigel 53 Searching for all possible matches within each subject string can be requested
200 nigel 75 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
201 nigel 53 again to search the remainder of the subject string. The difference between
202 nigel 75 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
203     \fBpcre_exec()\fP to start searching at a new point within the entire string
204 nigel 53 (which is in effect what Perl does), whereas the latter passes over a shortened
205     substring. This makes a difference to the matching process if the pattern
206 nigel 75 begins with a lookbehind assertion (including \eb or \eB).
207     .P
208     If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
209 nigel 53 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
210     flags set in order to search for another, non-empty, match at the same point.
211     If this second match fails, the start offset is advanced by one, and the normal
212     match is retried. This imitates the way Perl handles such cases when using the
213 nigel 75 \fB/g\fP modifier or the \fBsplit()\fP function.
214 nigel 91 .
215     .
216     .SS "Other modifiers"
217     .rs
218     .sp
219 nigel 75 There are yet more modifiers for controlling the way \fBpcretest\fP
220 nigel 53 operates.
221 nigel 75 .P
222     The \fB/+\fP modifier requests that as well as outputting the substring that
223 nigel 53 matched the entire pattern, pcretest should in addition output the remainder of
224     the subject string. This is useful for tests where the subject contains
225     multiple copies of the same substring.
226 nigel 75 .P
227 nigel 93 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
228 ph10 123 output a representation of the compiled byte code after compilation. Normally
229 ph10 116 this information contains length and offset values; however, if \fB/Z\fP is
230     also present, this data is replaced by spaces. This is a special feature for
231     use in the automatic test scripts; it ensures that the same output is generated
232     for different internal link sizes.
233 nigel 93 .P
234 nigel 75 The \fB/L\fP modifier must be followed directly by the name of a locale, for
235 nigel 53 example,
236 nigel 75 .sp
237     /pattern/Lfr_FR
238     .sp
239     For this reason, it must be the last modifier. The given locale is set,
240     \fBpcre_maketables()\fP is called to build a set of character tables for the
241     locale, and this is then passed to \fBpcre_compile()\fP when compiling the
242     regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
243     pointer; that is, \fB/L\fP applies only to the expression on which it appears.
244     .P
245     The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
246     compiled pattern (whether it is anchored, has a fixed first character, and
247     so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
248     pattern. If the pattern is studied, the results of that are also output.
249     .P
250 nigel 93 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
251 ph10 148 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
252 nigel 75 .P
253     The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
254     fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
255     facility is for testing the feature in PCRE that allows it to execute patterns
256     that were compiled on a host with a different endianness. This feature is not
257     available when the POSIX interface to PCRE is being used, that is, when the
258     \fB/P\fP pattern modifier is specified. See also the section about saving and
259     reloading compiled patterns below.
260     .P
261     The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
262 nigel 53 expression has been compiled, and the results used when the expression is
263     matched.
264 nigel 75 .P
265     The \fB/M\fP modifier causes the size of memory block used to hold the compiled
266 nigel 53 pattern to be output.
267 nigel 75 .P
268     The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
269 nigel 53 API rather than its native API. When this is done, all other modifiers except
270 nigel 75 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
271     present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
272 nigel 53 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
273 nigel 75 .P
274     The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
275 nigel 63 option set. This turns on support for UTF-8 character handling in PCRE,
276     provided that it was compiled with this support enabled. This modifier also
277     causes any non-printing characters in output strings to be printed using the
278 nigel 75 \ex{hh...} notation if they are valid UTF-8 sequences.
279     .P
280     If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
281     call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
282 nigel 71 checking of the string for UTF-8 validity.
283 nigel 75 .
284     .
285     .SH "DATA LINES"
286 nigel 63 .rs
287     .sp
288 nigel 75 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
289     whitespace is removed, and it is then scanned for \e escapes. Some of these are
290 nigel 63 pretty esoteric features, intended for checking out some of the more
291     complicated features of PCRE. If you are just testing "ordinary" regular
292     expressions, you probably don't need any of these. The following escapes are
293 nigel 53 recognized:
294 nigel 75 .sp
295 nigel 93 \ea alarm (BEL, \ex07)
296     \eb backspace (\ex08)
297     \ee escape (\ex27)
298     \ef formfeed (\ex0c)
299     \en newline (\ex0a)
300 nigel 91 .\" JOIN
301     \eqdd set the PCRE_MATCH_LIMIT limit to dd
302     (any number of digits)
303 nigel 93 \er carriage return (\ex0d)
304     \et tab (\ex09)
305     \ev vertical tab (\ex0b)
306 nigel 75 \ennn octal character (up to 3 octal digits)
307     \exhh hexadecimal character (up to 2 hex digits)
308     .\" JOIN
309     \ex{hh...} hexadecimal character, any number of digits
310 nigel 63 in UTF-8 mode
311 nigel 91 .\" JOIN
312 nigel 75 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
313 nigel 91 or \fBpcre_dfa_exec()\fP
314     .\" JOIN
315 nigel 75 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
316 nigel 91 or \fBpcre_dfa_exec()\fP
317 nigel 75 .\" JOIN
318     \eCdd call pcre_copy_substring() for substring dd
319     after a successful match (number less than 32)
320     .\" JOIN
321     \eCname call pcre_copy_named_substring() for substring
322 nigel 63 "name" after a successful match (name termin-
323     ated by next non alphanumeric character)
324 nigel 75 .\" JOIN
325     \eC+ show the current captured substrings at callout
326 nigel 63 time
327 nigel 75 \eC- do not supply a callout function
328     .\" JOIN
329     \eC!n return 1 instead of 0 when callout number n is
330 nigel 63 reached
331 nigel 75 .\" JOIN
332     \eC!n!m return 1 instead of 0 when callout number n is
333 nigel 63 reached for the nth time
334 nigel 75 .\" JOIN
335     \eC*n pass the number n (may be negative) as callout
336     data; this is used as the callout return value
337 nigel 77 \eD use the \fBpcre_dfa_exec()\fP match function
338     \eF only shortest match for \fBpcre_dfa_exec()\fP
339 nigel 75 .\" JOIN
340     \eGdd call pcre_get_substring() for substring dd
341     after a successful match (number less than 32)
342     .\" JOIN
343     \eGname call pcre_get_named_substring() for substring
344 nigel 63 "name" after a successful match (name termin-
345     ated by next non-alphanumeric character)
346 nigel 75 .\" JOIN
347     \eL call pcre_get_substringlist() after a
348 nigel 63 successful match
349 nigel 91 .\" JOIN
350 nigel 87 \eM discover the minimum MATCH_LIMIT and
351     MATCH_LIMIT_RECURSION settings
352 nigel 91 .\" JOIN
353 nigel 75 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
354 nigel 91 or \fBpcre_dfa_exec()\fP
355 nigel 75 .\" JOIN
356     \eOdd set the size of the output vector passed to
357     \fBpcre_exec()\fP to dd (any number of digits)
358 nigel 77 .\" JOIN
359 nigel 75 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
360 nigel 77 or \fBpcre_dfa_exec()\fP
361 nigel 91 .\" JOIN
362     \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
363     (any number of digits)
364 nigel 77 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
365 nigel 75 \eS output details of memory get/free calls during matching
366 nigel 91 .\" JOIN
367 nigel 75 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
368 nigel 91 or \fBpcre_dfa_exec()\fP
369 nigel 75 .\" JOIN
370     \e? pass the PCRE_NO_UTF8_CHECK option to
371 nigel 91 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
372 nigel 75 \e>dd start the match at offset dd (any number of digits);
373 nigel 91 .\" JOIN
374 nigel 75 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
375 nigel 91 or \fBpcre_dfa_exec()\fP
376     .\" JOIN
377     \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
378     or \fBpcre_dfa_exec()\fP
379     .\" JOIN
380     \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
381     or \fBpcre_dfa_exec()\fP
382     .\" JOIN
383     \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
384     or \fBpcre_dfa_exec()\fP
385 nigel 93 .\" JOIN
386 ph10 149 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
387     or \fBpcre_dfa_exec()\fP
388     .\" JOIN
389 nigel 93 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
390     or \fBpcre_dfa_exec()\fP
391 nigel 75 .sp
392 nigel 93 The escapes that specify line ending sequences are literal strings, exactly as
393     shown. No more than one newline setting should be present in any data line.
394 nigel 75 .P
395 nigel 93 A backslash followed by anything else just escapes the anything else. If
396     the very last character is a backslash, it is ignored. This gives a way of
397     passing an empty line as data, since a real empty line terminates the data
398     input.
399     .P
400 nigel 75 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
401 nigel 87 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
402     fields of the \fBpcre_extra\fP data structure, until it finds the minimum
403     numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
404     \fImatch_limit\fP number is a measure of the amount of backtracking that takes
405     place, and checking it out can be instructive. For most simple matches, the
406     number is quite small, but for patterns with very large numbers of matching
407     possibilities, it can become large very quickly with increasing length of
408     subject string. The \fImatch_limit_recursion\fP number is a measure of how much
409     stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
410     to complete the match attempt.
411 nigel 75 .P
412     When \eO is used, the value specified may be higher or lower than the size set
413     by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
414     the call of \fBpcre_exec()\fP for the line in which it appears.
415     .P
416     If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
417 nigel 87 API to be used, the only option-setting sequences that have any effect are \eB
418     and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
419     \fBregexec()\fP.
420 nigel 75 .P
421     The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
422     of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
423 nigel 53 any number of hexadecimal digits inside the braces. The result is from one to
424 ph10 211 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
425     allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
426     valid Unicode code points, or indeed valid UTF-8 characters according to the
427     later rules in RFC 3629.
428 nigel 75 .
429     .
430 nigel 77 .SH "THE ALTERNATIVE MATCHING FUNCTION"
431 nigel 63 .rs
432     .sp
433 nigel 77 By default, \fBpcretest\fP uses the standard PCRE matching function,
434     \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
435     alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
436     different way, and has some restrictions. The differences between the two
437     functions are described in the
438     .\" HREF
439     \fBpcrematching\fP
440     .\"
441     documentation.
442     .P
443     If a data line contains the \eD escape sequence, or if the command line
444     contains the \fB-dfa\fP option, the alternative matching function is called.
445     This function finds all possible matches at a given point. If, however, the \eF
446     escape sequence is present in the data line, it stops after the first match is
447     found. This is always the shortest possible match.
448     .
449     .
450     .SH "DEFAULT OUTPUT FROM PCRETEST"
451     .rs
452     .sp
453     This section describes the output when the normal matching function,
454     \fBpcre_exec()\fP, is being used.
455     .P
456 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
457 nigel 75 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
458     the whole pattern. Otherwise, it outputs "No match" or "Partial match"
459     when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
460     respectively, and otherwise the PCRE negative error number. Here is an example
461 nigel 77 of an interactive \fBpcretest\fP run.
462 nigel 75 .sp
463 nigel 53 $ pcretest
464 nigel 93 PCRE version 7.0 30-Nov-2006
465 nigel 75 .sp
466     re> /^abc(\ed+)/
467 nigel 53 data> abc123
468     0: abc123
469     1: 123
470     data> xyz
471     No match
472 nigel 75 .sp
473 ph10 286 Note that unset capturing substrings that are not followed by one that is set
474 ph10 273 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
475     the following example, there are two capturing substrings, but when the first
476 ph10 286 data line is matched, the second, unset substring is not shown. An "internal"
477 ph10 273 unset substring is shown as "<unset>", as for the second data line.
478     .sp
479     re> /(a)|(b)/
480     data> a
481     0: a
482     1: a
483     data> b
484     0: b
485     1: <unset>
486 ph10 286 2: b
487 ph10 273 .sp
488 nigel 75 If the strings contain any non-printing characters, they are output as \e0x
489     escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
490 nigel 93 pattern. See below for the definition of non-printing characters. If the
491     pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
492     the the rest of the subject string, identified by "0+" like this:
493 nigel 75 .sp
494 nigel 53 re> /cat/+
495     data> cataract
496     0: cat
497     0+ aract
498 nigel 75 .sp
499     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
500 nigel 53 matching attempts are output in sequence, like this:
501 nigel 75 .sp
502     re> /\eBi(\ew\ew)/g
503 nigel 53 data> Mississippi
504     0: iss
505     1: ss
506     0: iss
507     1: ss
508     0: ipp
509     1: pp
510 nigel 75 .sp
511 nigel 53 "No match" is output only if the first match attempt fails.
512 nigel 75 .P
513     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
514 nigel 53 data line that is successfully matched, the substrings extracted by the
515     convenience functions are output with C, G, or L after the string number
516     instead of a colon. This is in addition to the normal full list. The string
517     length (that is, the return from the extraction function) is given in
518 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
519     .P
520 nigel 93 Note that whereas patterns can be continued over several lines (a plain ">"
521 nigel 53 prompt is used for continuations), data lines may not. However newlines can be
522 nigel 93 included in data by means of the \en escape (or \er, \er\en, etc., depending on
523     the newline sequence setting).
524 nigel 75 .
525     .
526 nigel 93 .
527 nigel 77 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
528     .rs
529     .sp
530     When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
531     means of the \eD escape sequence or the \fB-dfa\fP command line option), the
532     output consists of a list of all the matches that start at the first point in
533     the subject where there is at least one match. For example:
534     .sp
535     re> /(tang|tangerine|tan)/
536     data> yellow tangerine\eD
537     0: tangerine
538     1: tang
539     2: tan
540     .sp
541     (Using the normal matching function on this data finds only "tang".) The
542     longest matching string is always given first (and numbered zero).
543     .P
544 nigel 93 If \fB/g\fP is present on the pattern, the search for further matches resumes
545 nigel 77 at the end of the longest match. For example:
546     .sp
547     re> /(tang|tangerine|tan)/g
548     data> yellow tangerine and tangy sultana\eD
549     0: tangerine
550     1: tang
551     2: tan
552     0: tang
553     1: tan
554     0: tan
555     .sp
556     Since the matching function does not support substring capture, the escape
557     sequences that are concerned with captured substrings are not relevant.
558     .
559     .
560     .SH "RESTARTING AFTER A PARTIAL MATCH"
561     .rs
562     .sp
563     When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
564     indicating that the subject partially matched the pattern, you can restart the
565     match with additional subject data by means of the \eR escape sequence. For
566     example:
567     .sp
568 ph10 155 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
569 nigel 77 data> 23ja\eP\eD
570     Partial match: 23ja
571     data> n05\eR\eD
572     0: n05
573     .sp
574     For further information about partial matching, see the
575     .\" HREF
576     \fBpcrepartial\fP
577     .\"
578     documentation.
579     .
580     .
581 nigel 75 .SH CALLOUTS
582     .rs
583     .sp
584     If the pattern contains any callout requests, \fBpcretest\fP's callout function
585 nigel 77 is called during matching. This works with both matching functions. By default,
586     the called function displays the callout number, the start and current
587     positions in the text at the callout time, and the next pattern item to be
588     tested. For example, the output
589 nigel 75 .sp
590     --->pqrabcdef
591     0 ^ ^ \ed
592     .sp
593     indicates that callout number 0 occurred for a match attempt starting at the
594     fourth character of the subject string, when the pointer was at the seventh
595     character of the data, and when the next pattern item was \ed. Just one
596     circumflex is output if the start and current positions are the same.
597     .P
598     Callouts numbered 255 are assumed to be automatic callouts, inserted as a
599     result of the \fB/C\fP pattern modifier. In this case, instead of showing the
600     callout number, the offset in the pattern, preceded by a plus, is output. For
601     example:
602     .sp
603     re> /\ed?[A-E]\e*/C
604     data> E*
605     --->E*
606     +0 ^ \ed?
607     +3 ^ [A-E]
608     +8 ^^ \e*
609     +10 ^ ^
610     0: E*
611     .sp
612     The callout function in \fBpcretest\fP returns zero (carry on matching) by
613 nigel 77 default, but you can use a \eC item in a data line (as described above) to
614 nigel 75 change this.
615     .P
616     Inserting callouts can be helpful when using \fBpcretest\fP to check
617     complicated regular expressions. For further information about callouts, see
618     the
619     .\" HREF
620     \fBpcrecallout\fP
621     .\"
622     documentation.
623     .
624     .
625 nigel 93 .
626     .SH "NON-PRINTING CHARACTERS"
627     .rs
628     .sp
629     When \fBpcretest\fP is outputting text in the compiled version of a pattern,
630     bytes other than 32-126 are always treated as non-printing characters are are
631     therefore shown as hex escapes.
632     .P
633     When \fBpcretest\fP is outputting text that is a matched part of a subject
634     string, it behaves in the same way, unless a different locale has been set for
635     the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
636     function to distinguish printing and non-printing characters.
637     .
638     .
639     .
640 nigel 75 .SH "SAVING AND RELOADING COMPILED PATTERNS"
641     .rs
642     .sp
643     The facilities described in this section are not available when the POSIX
644     inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
645     specified.
646     .P
647     When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
648     compiled pattern to a file, by following the modifiers with > and a file name.
649     For example:
650     .sp
651     /pattern/im >/some/file
652     .sp
653     See the
654     .\" HREF
655     \fBpcreprecompile\fP
656     .\"
657     documentation for a discussion about saving and re-using compiled patterns.
658     .P
659     The data that is written is binary. The first eight bytes are the length of the
660     compiled pattern data followed by the length of the optional study data, each
661     written as four bytes in big-endian order (most significant byte first). If
662     there is no study data (either the pattern was not studied, or studying did not
663     return any data), the second length is zero. The lengths are followed by an
664     exact copy of the compiled pattern. If there is additional study data, this
665     follows immediately after the compiled pattern. After writing the file,
666     \fBpcretest\fP expects to read a new pattern.
667     .P
668     A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
669     name instead of a pattern. The name of the file must not contain a < character,
670     as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
671     characters.
672     For example:
673     .sp
674     re> </some/file
675     Compiled regex loaded from /some/file
676     No study data
677     .sp
678     When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
679     the usual way.
680     .P
681     You can copy a file written by \fBpcretest\fP to a different host and reload it
682     there, even if the new host has opposite endianness to the one on which the
683     pattern was compiled. For example, you can compile on an i86 machine and run on
684     a SPARC machine.
685     .P
686     File names for saving and reloading can be absolute or relative, but note that
687     the shell facility of expanding a file name that starts with a tilde (~) is not
688     available.
689     .P
690     The ability to save and reload files in \fBpcretest\fP is intended for testing
691     and experimentation. It is not intended for production use because only a
692     single pattern can be written to a file. Furthermore, there is no facility for
693     supplying custom character tables for use with a reloaded pattern. If the
694     original pattern was compiled with custom tables, an attempt to match a subject
695     string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
696     Finally, if you attempt to load a file that is not in the correct format, the
697     result is undefined.
698     .
699     .
700 nigel 93 .SH "SEE ALSO"
701     .rs
702     .sp
703     \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
704 ph10 148 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
705 nigel 93 .
706     .
707 nigel 53 .SH AUTHOR
708 nigel 63 .rs
709     .sp
710 ph10 99 .nf
711 nigel 77 Philip Hazel
712 ph10 99 University Computing Service
713 nigel 93 Cambridge CB2 3QH, England.
714 ph10 99 .fi
715     .
716     .
717     .SH REVISION
718     .rs
719     .sp
720     .nf
721 ph10 336 Last updated: 12 April 2008
722     Copyright (c) 1997-2008 University of Cambridge.
723 ph10 99 .fi

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