/[pcre]/code/trunk/doc/pcretest.1
ViewVC logotype

Contents of /code/trunk/doc/pcretest.1

Parent Directory Parent Directory | Revision Log Revision Log


Revision 273 - (hide annotations) (download)
Mon Nov 19 10:09:04 2007 UTC (6 years, 11 months ago) by ph10
File size: 27959 byte(s)
Update pcretest doc to clarify the output for unset substrings.

1 nigel 53 .TH PCRETEST 1
2     .SH NAME
3     pcretest - a program for testing Perl-compatible regular expressions.
4     .SH SYNOPSIS
5 nigel 75 .rs
6     .sp
7 nigel 91 .B pcretest "[options] [source] [destination]"
8     .sp
9 nigel 75 \fBpcretest\fP was written as a test program for the PCRE regular expression
10 nigel 53 library itself, but it can also be used for experimenting with regular
11 nigel 63 expressions. This document describes the features of the test program; for
12     details of the regular expressions themselves, see the
13     .\" HREF
14 nigel 75 \fBpcrepattern\fP
15 nigel 63 .\"
16 nigel 75 documentation. For details of the PCRE library function calls and their
17     options, see the
18 nigel 63 .\" HREF
19 nigel 75 \fBpcreapi\fP
20 nigel 63 .\"
21     documentation.
22 nigel 75 .
23     .
24 nigel 53 .SH OPTIONS
25 nigel 63 .rs
26 nigel 53 .TP 10
27 nigel 93 \fB-b\fP
28     Behave as if each regex has the \fB/B\fP (show bytecode) modifier; the internal
29     form is output after compilation.
30     .TP 10
31 nigel 75 \fB-C\fP
32 nigel 63 Output the version number of the PCRE library, and all available information
33     about the optional features that are included, and then exit.
34     .TP 10
35 nigel 75 \fB-d\fP
36 nigel 77 Behave as if each regex has the \fB/D\fP (debug) modifier; the internal
37 nigel 93 form and information about the compiled pattern is output after compilation;
38     \fB-d\fP is equivalent to \fB-b -i\fP.
39 nigel 53 .TP 10
40 nigel 77 \fB-dfa\fP
41     Behave as if each data line contains the \eD escape sequence; this causes the
42     alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the
43     standard \fBpcre_exec()\fP function (more detail is given below).
44     .TP 10
45 nigel 93 \fB-help\fP
46     Output a brief summary these options and then exit.
47     .TP 10
48 nigel 75 \fB-i\fP
49 nigel 77 Behave as if each regex has the \fB/I\fP modifier; information about the
50 nigel 53 compiled pattern is given after compilation.
51     .TP 10
52 nigel 75 \fB-m\fP
53 nigel 53 Output the size of each compiled pattern after it has been compiled. This is
54 nigel 75 equivalent to adding \fB/M\fP to each regular expression. For compatibility
55     with earlier versions of pcretest, \fB-s\fP is a synonym for \fB-m\fP.
56 nigel 53 .TP 10
57 nigel 75 \fB-o\fP \fIosize\fP
58     Set the number of elements in the output vector that is used when calling
59 nigel 93 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
60     is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
61     22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
62     changed for individual matching calls by including \eO in the data line (see
63     below).
64 nigel 53 .TP 10
65 nigel 75 \fB-p\fP
66 nigel 77 Behave as if each regex has the \fB/P\fP modifier; the POSIX wrapper API is
67     used to call PCRE. None of the other options has any effect when \fB-p\fP is
68     set.
69 nigel 53 .TP 10
70 nigel 91 \fB-q\fP
71 nigel 87 Do not output the version number of \fBpcretest\fP at the start of execution.
72     .TP 10
73 nigel 91 \fB-S\fP \fIsize\fP
74     On Unix-like systems, set the size of the runtime stack to \fIsize\fP
75     megabytes.
76     .TP 10
77 nigel 75 \fB-t\fP
78 nigel 63 Run each compile, study, and match many times with a timer, and output
79 nigel 75 resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
80     \fB-t\fP, because you will then get the size output a zillion times, and the
81 nigel 93 timing will be distorted. You can control the number of iterations that are
82     used for timing by following \fB-t\fP with a number (as a separate item on the
83     command line). For example, "-t 1000" would iterate 1000 times. The default is
84     to iterate 500000 times.
85     .TP 10
86     \fB-tm\fP
87     This is like \fB-t\fP except that it times only the matching phase, not the
88     compile or study phases.
89 nigel 75 .
90     .
91 nigel 53 .SH DESCRIPTION
92 nigel 63 .rs
93     .sp
94 nigel 75 If \fBpcretest\fP is given two filename arguments, it reads from the first and
95 nigel 53 writes to the second. If it is given only one filename argument, it reads from
96     that file and writes to stdout. Otherwise, it reads from stdin and writes to
97     stdout, and prompts for each line of input, using "re>" to prompt for regular
98     expressions, and "data>" to prompt for data lines.
99 nigel 75 .P
100 nigel 53 The program handles any number of sets of input on a single input file. Each
101     set starts with a regular expression, and continues with any number of data
102 nigel 63 lines to be matched against the pattern.
103 nigel 75 .P
104     Each data line is matched separately and independently. If you want to do
105 nigel 91 multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
106 nigel 93 etc., depending on the newline setting) in a single line of input to encode the
107     newline sequences. There is no limit on the length of data lines; the input
108 nigel 91 buffer is automatically extended if it is too small.
109 nigel 75 .P
110 nigel 63 An empty line signals the end of the data lines, at which point a new regular
111     expression is read. The regular expressions are given enclosed in any
112 nigel 91 non-alphanumeric delimiters other than backslash, for example:
113 nigel 75 .sp
114 nigel 53 /(a|bc)x+yz/
115 nigel 75 .sp
116 nigel 53 White space before the initial delimiter is ignored. A regular expression may
117     be continued over several input lines, in which case the newline characters are
118     included within it. It is possible to include the delimiter within the pattern
119     by escaping it, for example
120 nigel 75 .sp
121     /abc\e/def/
122     .sp
123 nigel 53 If you do so, the escape and the delimiter form part of the pattern, but since
124 nigel 75 delimiters are always non-alphanumeric, this does not affect its interpretation.
125 nigel 53 If the terminating delimiter is immediately followed by a backslash, for
126     example,
127 nigel 75 .sp
128     /abc/\e
129     .sp
130 nigel 53 then a backslash is added to the end of the pattern. This is done to provide a
131     way of testing the error condition that arises if a pattern finishes with a
132     backslash, because
133 nigel 75 .sp
134     /abc\e/
135     .sp
136 nigel 53 is interpreted as the first line of a pattern that starts with "abc/", causing
137     pcretest to read the next line as a continuation of the regular expression.
138 nigel 75 .
139     .
140     .SH "PATTERN MODIFIERS"
141 nigel 63 .rs
142     .sp
143 nigel 75 A pattern may be followed by any number of modifiers, which are mostly single
144     characters. Following Perl usage, these are referred to below as, for example,
145     "the \fB/i\fP modifier", even though the delimiter of the pattern need not
146     always be a slash, and no slash is used when writing modifiers. Whitespace may
147     appear between the final pattern delimiter and the first modifier, and between
148     the modifiers themselves.
149     .P
150     The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
151     PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
152     \fBpcre_compile()\fP is called. These four modifier letters have the same
153     effect as they do in Perl. For example:
154     .sp
155 nigel 53 /caseless/i
156 nigel 75 .sp
157     The following table shows additional modifiers for setting PCRE options that do
158     not correspond to anything in Perl:
159     .sp
160 ph10 231 \fB/A\fP PCRE_ANCHORED
161     \fB/C\fP PCRE_AUTO_CALLOUT
162     \fB/E\fP PCRE_DOLLAR_ENDONLY
163     \fB/f\fP PCRE_FIRSTLINE
164     \fB/J\fP PCRE_DUPNAMES
165     \fB/N\fP PCRE_NO_AUTO_CAPTURE
166     \fB/U\fP PCRE_UNGREEDY
167     \fB/X\fP PCRE_EXTRA
168     \fB/<cr>\fP PCRE_NEWLINE_CR
169     \fB/<lf>\fP PCRE_NEWLINE_LF
170     \fB/<crlf>\fP PCRE_NEWLINE_CRLF
171     \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
172     \fB/<any>\fP PCRE_NEWLINE_ANY
173     \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
174     \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
175 nigel 75 .sp
176 ph10 227 Those specifying line ending sequences are literal strings as shown, but the
177     letters can be in either case. This example sets multiline matching with CRLF
178     as the line ending sequence:
179 nigel 93 .sp
180     /^abc/m<crlf>
181     .sp
182     Details of the meanings of these PCRE options are given in the
183 nigel 91 .\" HREF
184     \fBpcreapi\fP
185     .\"
186     documentation.
187     .
188     .
189     .SS "Finding all matches in a string"
190     .rs
191     .sp
192 nigel 53 Searching for all possible matches within each subject string can be requested
193 nigel 75 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
194 nigel 53 again to search the remainder of the subject string. The difference between
195 nigel 75 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
196     \fBpcre_exec()\fP to start searching at a new point within the entire string
197 nigel 53 (which is in effect what Perl does), whereas the latter passes over a shortened
198     substring. This makes a difference to the matching process if the pattern
199 nigel 75 begins with a lookbehind assertion (including \eb or \eB).
200     .P
201     If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
202 nigel 53 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
203     flags set in order to search for another, non-empty, match at the same point.
204     If this second match fails, the start offset is advanced by one, and the normal
205     match is retried. This imitates the way Perl handles such cases when using the
206 nigel 75 \fB/g\fP modifier or the \fBsplit()\fP function.
207 nigel 91 .
208     .
209     .SS "Other modifiers"
210     .rs
211     .sp
212 nigel 75 There are yet more modifiers for controlling the way \fBpcretest\fP
213 nigel 53 operates.
214 nigel 75 .P
215     The \fB/+\fP modifier requests that as well as outputting the substring that
216 nigel 53 matched the entire pattern, pcretest should in addition output the remainder of
217     the subject string. This is useful for tests where the subject contains
218     multiple copies of the same substring.
219 nigel 75 .P
220 nigel 93 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
221 ph10 123 output a representation of the compiled byte code after compilation. Normally
222 ph10 116 this information contains length and offset values; however, if \fB/Z\fP is
223     also present, this data is replaced by spaces. This is a special feature for
224     use in the automatic test scripts; it ensures that the same output is generated
225     for different internal link sizes.
226 nigel 93 .P
227 nigel 75 The \fB/L\fP modifier must be followed directly by the name of a locale, for
228 nigel 53 example,
229 nigel 75 .sp
230     /pattern/Lfr_FR
231     .sp
232     For this reason, it must be the last modifier. The given locale is set,
233     \fBpcre_maketables()\fP is called to build a set of character tables for the
234     locale, and this is then passed to \fBpcre_compile()\fP when compiling the
235     regular expression. Without an \fB/L\fP modifier, NULL is passed as the tables
236     pointer; that is, \fB/L\fP applies only to the expression on which it appears.
237     .P
238     The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
239     compiled pattern (whether it is anchored, has a fixed first character, and
240     so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
241     pattern. If the pattern is studied, the results of that are also output.
242     .P
243 nigel 93 The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
244 ph10 148 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
245 nigel 75 .P
246     The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
247     fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
248     facility is for testing the feature in PCRE that allows it to execute patterns
249     that were compiled on a host with a different endianness. This feature is not
250     available when the POSIX interface to PCRE is being used, that is, when the
251     \fB/P\fP pattern modifier is specified. See also the section about saving and
252     reloading compiled patterns below.
253     .P
254     The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
255 nigel 53 expression has been compiled, and the results used when the expression is
256     matched.
257 nigel 75 .P
258     The \fB/M\fP modifier causes the size of memory block used to hold the compiled
259 nigel 53 pattern to be output.
260 nigel 75 .P
261     The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
262 nigel 53 API rather than its native API. When this is done, all other modifiers except
263 nigel 75 \fB/i\fP, \fB/m\fP, and \fB/+\fP are ignored. REG_ICASE is set if \fB/i\fP is
264     present, and REG_NEWLINE is set if \fB/m\fP is present. The wrapper functions
265 nigel 53 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
266 nigel 75 .P
267     The \fB/8\fP modifier causes \fBpcretest\fP to call PCRE with the PCRE_UTF8
268 nigel 63 option set. This turns on support for UTF-8 character handling in PCRE,
269     provided that it was compiled with this support enabled. This modifier also
270     causes any non-printing characters in output strings to be printed using the
271 nigel 75 \ex{hh...} notation if they are valid UTF-8 sequences.
272     .P
273     If the \fB/?\fP modifier is used with \fB/8\fP, it causes \fBpcretest\fP to
274     call \fBpcre_compile()\fP with the PCRE_NO_UTF8_CHECK option, to suppress the
275 nigel 71 checking of the string for UTF-8 validity.
276 nigel 75 .
277     .
278     .SH "DATA LINES"
279 nigel 63 .rs
280     .sp
281 nigel 75 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
282     whitespace is removed, and it is then scanned for \e escapes. Some of these are
283 nigel 63 pretty esoteric features, intended for checking out some of the more
284     complicated features of PCRE. If you are just testing "ordinary" regular
285     expressions, you probably don't need any of these. The following escapes are
286 nigel 53 recognized:
287 nigel 75 .sp
288 nigel 93 \ea alarm (BEL, \ex07)
289     \eb backspace (\ex08)
290     \ee escape (\ex27)
291     \ef formfeed (\ex0c)
292     \en newline (\ex0a)
293 nigel 91 .\" JOIN
294     \eqdd set the PCRE_MATCH_LIMIT limit to dd
295     (any number of digits)
296 nigel 93 \er carriage return (\ex0d)
297     \et tab (\ex09)
298     \ev vertical tab (\ex0b)
299 nigel 75 \ennn octal character (up to 3 octal digits)
300     \exhh hexadecimal character (up to 2 hex digits)
301     .\" JOIN
302     \ex{hh...} hexadecimal character, any number of digits
303 nigel 63 in UTF-8 mode
304 nigel 91 .\" JOIN
305 nigel 75 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
306 nigel 91 or \fBpcre_dfa_exec()\fP
307     .\" JOIN
308 nigel 75 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
309 nigel 91 or \fBpcre_dfa_exec()\fP
310 nigel 75 .\" JOIN
311     \eCdd call pcre_copy_substring() for substring dd
312     after a successful match (number less than 32)
313     .\" JOIN
314     \eCname call pcre_copy_named_substring() for substring
315 nigel 63 "name" after a successful match (name termin-
316     ated by next non alphanumeric character)
317 nigel 75 .\" JOIN
318     \eC+ show the current captured substrings at callout
319 nigel 63 time
320 nigel 75 \eC- do not supply a callout function
321     .\" JOIN
322     \eC!n return 1 instead of 0 when callout number n is
323 nigel 63 reached
324 nigel 75 .\" JOIN
325     \eC!n!m return 1 instead of 0 when callout number n is
326 nigel 63 reached for the nth time
327 nigel 75 .\" JOIN
328     \eC*n pass the number n (may be negative) as callout
329     data; this is used as the callout return value
330 nigel 77 \eD use the \fBpcre_dfa_exec()\fP match function
331     \eF only shortest match for \fBpcre_dfa_exec()\fP
332 nigel 75 .\" JOIN
333     \eGdd call pcre_get_substring() for substring dd
334     after a successful match (number less than 32)
335     .\" JOIN
336     \eGname call pcre_get_named_substring() for substring
337 nigel 63 "name" after a successful match (name termin-
338     ated by next non-alphanumeric character)
339 nigel 75 .\" JOIN
340     \eL call pcre_get_substringlist() after a
341 nigel 63 successful match
342 nigel 91 .\" JOIN
343 nigel 87 \eM discover the minimum MATCH_LIMIT and
344     MATCH_LIMIT_RECURSION settings
345 nigel 91 .\" JOIN
346 nigel 75 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
347 nigel 91 or \fBpcre_dfa_exec()\fP
348 nigel 75 .\" JOIN
349     \eOdd set the size of the output vector passed to
350     \fBpcre_exec()\fP to dd (any number of digits)
351 nigel 77 .\" JOIN
352 nigel 75 \eP pass the PCRE_PARTIAL option to \fBpcre_exec()\fP
353 nigel 77 or \fBpcre_dfa_exec()\fP
354 nigel 91 .\" JOIN
355     \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
356     (any number of digits)
357 nigel 77 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
358 nigel 75 \eS output details of memory get/free calls during matching
359 nigel 91 .\" JOIN
360 nigel 75 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
361 nigel 91 or \fBpcre_dfa_exec()\fP
362 nigel 75 .\" JOIN
363     \e? pass the PCRE_NO_UTF8_CHECK option to
364 nigel 91 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
365 nigel 75 \e>dd start the match at offset dd (any number of digits);
366 nigel 91 .\" JOIN
367 nigel 75 this sets the \fIstartoffset\fP argument for \fBpcre_exec()\fP
368 nigel 91 or \fBpcre_dfa_exec()\fP
369     .\" JOIN
370     \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
371     or \fBpcre_dfa_exec()\fP
372     .\" JOIN
373     \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
374     or \fBpcre_dfa_exec()\fP
375     .\" JOIN
376     \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
377     or \fBpcre_dfa_exec()\fP
378 nigel 93 .\" JOIN
379 ph10 149 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
380     or \fBpcre_dfa_exec()\fP
381     .\" JOIN
382 nigel 93 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
383     or \fBpcre_dfa_exec()\fP
384 nigel 75 .sp
385 nigel 93 The escapes that specify line ending sequences are literal strings, exactly as
386     shown. No more than one newline setting should be present in any data line.
387 nigel 75 .P
388 nigel 93 A backslash followed by anything else just escapes the anything else. If
389     the very last character is a backslash, it is ignored. This gives a way of
390     passing an empty line as data, since a real empty line terminates the data
391     input.
392     .P
393 nigel 75 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
394 nigel 87 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
395     fields of the \fBpcre_extra\fP data structure, until it finds the minimum
396     numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
397     \fImatch_limit\fP number is a measure of the amount of backtracking that takes
398     place, and checking it out can be instructive. For most simple matches, the
399     number is quite small, but for patterns with very large numbers of matching
400     possibilities, it can become large very quickly with increasing length of
401     subject string. The \fImatch_limit_recursion\fP number is a measure of how much
402     stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
403     to complete the match attempt.
404 nigel 75 .P
405     When \eO is used, the value specified may be higher or lower than the size set
406     by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
407     the call of \fBpcre_exec()\fP for the line in which it appears.
408     .P
409     If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
410 nigel 87 API to be used, the only option-setting sequences that have any effect are \eB
411     and \eZ, causing REG_NOTBOL and REG_NOTEOL, respectively, to be passed to
412     \fBregexec()\fP.
413 nigel 75 .P
414     The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
415     of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
416 nigel 53 any number of hexadecimal digits inside the braces. The result is from one to
417 ph10 211 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
418     allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
419     valid Unicode code points, or indeed valid UTF-8 characters according to the
420     later rules in RFC 3629.
421 nigel 75 .
422     .
423 nigel 77 .SH "THE ALTERNATIVE MATCHING FUNCTION"
424 nigel 63 .rs
425     .sp
426 nigel 77 By default, \fBpcretest\fP uses the standard PCRE matching function,
427     \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
428     alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
429     different way, and has some restrictions. The differences between the two
430     functions are described in the
431     .\" HREF
432     \fBpcrematching\fP
433     .\"
434     documentation.
435     .P
436     If a data line contains the \eD escape sequence, or if the command line
437     contains the \fB-dfa\fP option, the alternative matching function is called.
438     This function finds all possible matches at a given point. If, however, the \eF
439     escape sequence is present in the data line, it stops after the first match is
440     found. This is always the shortest possible match.
441     .
442     .
443     .SH "DEFAULT OUTPUT FROM PCRETEST"
444     .rs
445     .sp
446     This section describes the output when the normal matching function,
447     \fBpcre_exec()\fP, is being used.
448     .P
449 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
450 nigel 75 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
451     the whole pattern. Otherwise, it outputs "No match" or "Partial match"
452     when \fBpcre_exec()\fP returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PARTIAL,
453     respectively, and otherwise the PCRE negative error number. Here is an example
454 nigel 77 of an interactive \fBpcretest\fP run.
455 nigel 75 .sp
456 nigel 53 $ pcretest
457 nigel 93 PCRE version 7.0 30-Nov-2006
458 nigel 75 .sp
459     re> /^abc(\ed+)/
460 nigel 53 data> abc123
461     0: abc123
462     1: 123
463     data> xyz
464     No match
465 nigel 75 .sp
466 ph10 273 Note that unset capturing substrings that are not followed by one that is set
467     are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
468     the following example, there are two capturing substrings, but when the first
469     data line is matched, the second, unset substring is not shown. An "internal"
470     unset substring is shown as "<unset>", as for the second data line.
471     .sp
472     re> /(a)|(b)/
473     data> a
474     0: a
475     1: a
476     data> b
477     0: b
478     1: <unset>
479     2: b
480     .sp
481 nigel 75 If the strings contain any non-printing characters, they are output as \e0x
482     escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
483 nigel 93 pattern. See below for the definition of non-printing characters. If the
484     pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
485     the the rest of the subject string, identified by "0+" like this:
486 nigel 75 .sp
487 nigel 53 re> /cat/+
488     data> cataract
489     0: cat
490     0+ aract
491 nigel 75 .sp
492     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
493 nigel 53 matching attempts are output in sequence, like this:
494 nigel 75 .sp
495     re> /\eBi(\ew\ew)/g
496 nigel 53 data> Mississippi
497     0: iss
498     1: ss
499     0: iss
500     1: ss
501     0: ipp
502     1: pp
503 nigel 75 .sp
504 nigel 53 "No match" is output only if the first match attempt fails.
505 nigel 75 .P
506     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
507 nigel 53 data line that is successfully matched, the substrings extracted by the
508     convenience functions are output with C, G, or L after the string number
509     instead of a colon. This is in addition to the normal full list. The string
510     length (that is, the return from the extraction function) is given in
511 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
512     .P
513 nigel 93 Note that whereas patterns can be continued over several lines (a plain ">"
514 nigel 53 prompt is used for continuations), data lines may not. However newlines can be
515 nigel 93 included in data by means of the \en escape (or \er, \er\en, etc., depending on
516     the newline sequence setting).
517 nigel 75 .
518     .
519 nigel 93 .
520 nigel 77 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
521     .rs
522     .sp
523     When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
524     means of the \eD escape sequence or the \fB-dfa\fP command line option), the
525     output consists of a list of all the matches that start at the first point in
526     the subject where there is at least one match. For example:
527     .sp
528     re> /(tang|tangerine|tan)/
529     data> yellow tangerine\eD
530     0: tangerine
531     1: tang
532     2: tan
533     .sp
534     (Using the normal matching function on this data finds only "tang".) The
535     longest matching string is always given first (and numbered zero).
536     .P
537 nigel 93 If \fB/g\fP is present on the pattern, the search for further matches resumes
538 nigel 77 at the end of the longest match. For example:
539     .sp
540     re> /(tang|tangerine|tan)/g
541     data> yellow tangerine and tangy sultana\eD
542     0: tangerine
543     1: tang
544     2: tan
545     0: tang
546     1: tan
547     0: tan
548     .sp
549     Since the matching function does not support substring capture, the escape
550     sequences that are concerned with captured substrings are not relevant.
551     .
552     .
553     .SH "RESTARTING AFTER A PARTIAL MATCH"
554     .rs
555     .sp
556     When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
557     indicating that the subject partially matched the pattern, you can restart the
558     match with additional subject data by means of the \eR escape sequence. For
559     example:
560     .sp
561 ph10 155 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
562 nigel 77 data> 23ja\eP\eD
563     Partial match: 23ja
564     data> n05\eR\eD
565     0: n05
566     .sp
567     For further information about partial matching, see the
568     .\" HREF
569     \fBpcrepartial\fP
570     .\"
571     documentation.
572     .
573     .
574 nigel 75 .SH CALLOUTS
575     .rs
576     .sp
577     If the pattern contains any callout requests, \fBpcretest\fP's callout function
578 nigel 77 is called during matching. This works with both matching functions. By default,
579     the called function displays the callout number, the start and current
580     positions in the text at the callout time, and the next pattern item to be
581     tested. For example, the output
582 nigel 75 .sp
583     --->pqrabcdef
584     0 ^ ^ \ed
585     .sp
586     indicates that callout number 0 occurred for a match attempt starting at the
587     fourth character of the subject string, when the pointer was at the seventh
588     character of the data, and when the next pattern item was \ed. Just one
589     circumflex is output if the start and current positions are the same.
590     .P
591     Callouts numbered 255 are assumed to be automatic callouts, inserted as a
592     result of the \fB/C\fP pattern modifier. In this case, instead of showing the
593     callout number, the offset in the pattern, preceded by a plus, is output. For
594     example:
595     .sp
596     re> /\ed?[A-E]\e*/C
597     data> E*
598     --->E*
599     +0 ^ \ed?
600     +3 ^ [A-E]
601     +8 ^^ \e*
602     +10 ^ ^
603     0: E*
604     .sp
605     The callout function in \fBpcretest\fP returns zero (carry on matching) by
606 nigel 77 default, but you can use a \eC item in a data line (as described above) to
607 nigel 75 change this.
608     .P
609     Inserting callouts can be helpful when using \fBpcretest\fP to check
610     complicated regular expressions. For further information about callouts, see
611     the
612     .\" HREF
613     \fBpcrecallout\fP
614     .\"
615     documentation.
616     .
617     .
618 nigel 93 .
619     .SH "NON-PRINTING CHARACTERS"
620     .rs
621     .sp
622     When \fBpcretest\fP is outputting text in the compiled version of a pattern,
623     bytes other than 32-126 are always treated as non-printing characters are are
624     therefore shown as hex escapes.
625     .P
626     When \fBpcretest\fP is outputting text that is a matched part of a subject
627     string, it behaves in the same way, unless a different locale has been set for
628     the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
629     function to distinguish printing and non-printing characters.
630     .
631     .
632     .
633 nigel 75 .SH "SAVING AND RELOADING COMPILED PATTERNS"
634     .rs
635     .sp
636     The facilities described in this section are not available when the POSIX
637     inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
638     specified.
639     .P
640     When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
641     compiled pattern to a file, by following the modifiers with > and a file name.
642     For example:
643     .sp
644     /pattern/im >/some/file
645     .sp
646     See the
647     .\" HREF
648     \fBpcreprecompile\fP
649     .\"
650     documentation for a discussion about saving and re-using compiled patterns.
651     .P
652     The data that is written is binary. The first eight bytes are the length of the
653     compiled pattern data followed by the length of the optional study data, each
654     written as four bytes in big-endian order (most significant byte first). If
655     there is no study data (either the pattern was not studied, or studying did not
656     return any data), the second length is zero. The lengths are followed by an
657     exact copy of the compiled pattern. If there is additional study data, this
658     follows immediately after the compiled pattern. After writing the file,
659     \fBpcretest\fP expects to read a new pattern.
660     .P
661     A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
662     name instead of a pattern. The name of the file must not contain a < character,
663     as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
664     characters.
665     For example:
666     .sp
667     re> </some/file
668     Compiled regex loaded from /some/file
669     No study data
670     .sp
671     When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
672     the usual way.
673     .P
674     You can copy a file written by \fBpcretest\fP to a different host and reload it
675     there, even if the new host has opposite endianness to the one on which the
676     pattern was compiled. For example, you can compile on an i86 machine and run on
677     a SPARC machine.
678     .P
679     File names for saving and reloading can be absolute or relative, but note that
680     the shell facility of expanding a file name that starts with a tilde (~) is not
681     available.
682     .P
683     The ability to save and reload files in \fBpcretest\fP is intended for testing
684     and experimentation. It is not intended for production use because only a
685     single pattern can be written to a file. Furthermore, there is no facility for
686     supplying custom character tables for use with a reloaded pattern. If the
687     original pattern was compiled with custom tables, an attempt to match a subject
688     string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
689     Finally, if you attempt to load a file that is not in the correct format, the
690     result is undefined.
691     .
692     .
693 nigel 93 .SH "SEE ALSO"
694     .rs
695     .sp
696     \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
697 ph10 148 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
698 nigel 93 .
699     .
700 nigel 53 .SH AUTHOR
701 nigel 63 .rs
702     .sp
703 ph10 99 .nf
704 nigel 77 Philip Hazel
705 ph10 99 University Computing Service
706 nigel 93 Cambridge CB2 3QH, England.
707 ph10 99 .fi
708     .
709     .
710     .SH REVISION
711     .rs
712     .sp
713     .nf
714 ph10 273 Last updated: 19 November 2007
715 ph10 99 Copyright (c) 1997-2007 University of Cambridge.
716     .fi

Properties

Name Value
svn:eol-style native
svn:keywords "Author Date Id Revision Url"

webmaster@exim.org
ViewVC Help
Powered by ViewVC 1.1.12