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Test for ridiculous values of starting offsets; tidy UTF-8 code.

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 ph10 518 The following table shows additional modifiers for setting PCRE compile-time
169     options that do not correspond to anything in Perl:
170 nigel 75 .sp
171 ph10 518 \fB/8\fP PCRE_UTF8
172 ph10 535 \fB/?\fP PCRE_NO_UTF8_CHECK
173 ph10 231 \fB/A\fP PCRE_ANCHORED
174     \fB/C\fP PCRE_AUTO_CALLOUT
175     \fB/E\fP PCRE_DOLLAR_ENDONLY
176     \fB/f\fP PCRE_FIRSTLINE
177     \fB/J\fP PCRE_DUPNAMES
178     \fB/N\fP PCRE_NO_AUTO_CAPTURE
179     \fB/U\fP PCRE_UNGREEDY
180 ph10 535 \fB/W\fP PCRE_UCP
181 ph10 231 \fB/X\fP PCRE_EXTRA
182 ph10 345 \fB/<JS>\fP PCRE_JAVASCRIPT_COMPAT
183 ph10 231 \fB/<cr>\fP PCRE_NEWLINE_CR
184     \fB/<lf>\fP PCRE_NEWLINE_LF
185     \fB/<crlf>\fP PCRE_NEWLINE_CRLF
186     \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
187     \fB/<any>\fP PCRE_NEWLINE_ANY
188     \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
189     \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
190 nigel 75 .sp
191 ph10 518 The modifiers that are enclosed in angle brackets are literal strings as shown,
192     including the angle brackets, but the letters can be in either case. This
193     example sets multiline matching with CRLF as the line ending sequence:
194 nigel 93 .sp
195     /^abc/m<crlf>
196     .sp
197 ph10 518 As well as turning on the PCRE_UTF8 option, the \fB/8\fP modifier also causes
198     any non-printing characters in output strings to be printed using the
199     \ex{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
200     options are given in the
201 nigel 91 .\" HREF
202     \fBpcreapi\fP
203     .\"
204 ph10 535 documentation.
205 nigel 91 .
206     .
207     .SS "Finding all matches in a string"
208     .rs
209     .sp
210 nigel 53 Searching for all possible matches within each subject string can be requested
211 nigel 75 by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
212 nigel 53 again to search the remainder of the subject string. The difference between
213 nigel 75 \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
214     \fBpcre_exec()\fP to start searching at a new point within the entire string
215 nigel 53 (which is in effect what Perl does), whereas the latter passes over a shortened
216     substring. This makes a difference to the matching process if the pattern
217 nigel 75 begins with a lookbehind assertion (including \eb or \eB).
218     .P
219     If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
220 ph10 442 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
221     PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
222 ph10 566 same point. If this second match fails, the start offset is advanced, and the
223     normal match is retried. This imitates the way Perl handles such cases when
224     using the \fB/g\fP modifier or the \fBsplit()\fP function. Normally, the start
225     offset is advanced by one character, but if the newline convention recognizes
226     CRLF as a newline, and the current character is CR followed by LF, an advance
227     of two is used.
228 nigel 91 .
229     .
230     .SS "Other modifiers"
231     .rs
232     .sp
233 nigel 75 There are yet more modifiers for controlling the way \fBpcretest\fP
234 nigel 53 operates.
235 nigel 75 .P
236     The \fB/+\fP modifier requests that as well as outputting the substring that
237 nigel 53 matched the entire pattern, pcretest should in addition output the remainder of
238     the subject string. This is useful for tests where the subject contains
239     multiple copies of the same substring.
240 nigel 75 .P
241 nigel 93 The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
242 ph10 123 output a representation of the compiled byte code after compilation. Normally
243 ph10 116 this information contains length and offset values; however, if \fB/Z\fP is
244     also present, this data is replaced by spaces. This is a special feature for
245     use in the automatic test scripts; it ensures that the same output is generated
246     for different internal link sizes.
247 nigel 93 .P
248     The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
249 ph10 148 \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
250 nigel 75 .P
251     The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
252     fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
253     facility is for testing the feature in PCRE that allows it to execute patterns
254     that were compiled on a host with a different endianness. This feature is not
255     available when the POSIX interface to PCRE is being used, that is, when the
256     \fB/P\fP pattern modifier is specified. See also the section about saving and
257     reloading compiled patterns below.
258     .P
259 ph10 510 The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
260     compiled pattern (whether it is anchored, has a fixed first character, and
261     so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
262     pattern. If the pattern is studied, the results of that are also output.
263 nigel 75 .P
264 ph10 510 The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking
265     control verbs that are returned from calls to \fBpcre_exec()\fP. It causes
266     \fBpcretest\fP to create a \fBpcre_extra\fP block if one has not already been
267     created by a call to \fBpcre_study()\fP, and to set the PCRE_EXTRA_MARK flag
268     and the \fBmark\fP field within it, every time that \fBpcre_exec()\fP is
269     called. If the variable that the \fBmark\fP field points to is non-NULL for a
270 ph10 512 match, non-match, or partial match, \fBpcretest\fP prints the string to which
271     it points. For a match, this is shown on a line by itself, tagged with "MK:".
272 ph10 510 For a non-match it is added to the message.
273     .P
274     The \fB/L\fP modifier must be followed directly by the name of a locale, for
275     example,
276     .sp
277     /pattern/Lfr_FR
278     .sp
279     For this reason, it must be the last modifier. The given locale is set,
280     \fBpcre_maketables()\fP is called to build a set of character tables for the
281     locale, and this is then passed to \fBpcre_compile()\fP when compiling the
282 ph10 541 regular expression. Without an \fB/L\fP (or \fB/T\fP) modifier, NULL is passed
283     as the tables pointer; that is, \fB/L\fP applies only to the expression on
284     which it appears.
285 ph10 510 .P
286 nigel 75 The \fB/M\fP modifier causes the size of memory block used to hold the compiled
287 nigel 53 pattern to be output.
288 nigel 75 .P
289 ph10 510 The \fB/S\fP modifier causes \fBpcre_study()\fP to be called after the
290     expression has been compiled, and the results used when the expression is
291     matched.
292 ph10 541 .P
293 ph10 545 The \fB/T\fP modifier must be followed by a single digit. It causes a specific
294     set of built-in character tables to be passed to \fBpcre_compile()\fP. It is
295     used in the standard PCRE tests to check behaviour with different character
296 ph10 541 tables. The digit specifies the tables as follows:
297     .sp
298 ph10 545 0 the default ASCII tables, as distributed in
299 ph10 541 pcre_chartables.c.dist
300     1 a set of tables defining ISO 8859 characters
301     .sp
302 ph10 545 In table 1, some characters whose codes are greater than 128 are identified as
303 ph10 541 letters, digits, spaces, etc.
304 nigel 75 .
305     .
306 ph10 518 .SS "Using the POSIX wrapper API"
307     .rs
308     .sp
309     The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
310 ph10 535 API rather than its native API. When \fB/P\fP is set, the following modifiers
311 ph10 518 set options for the \fBregcomp()\fP function:
312     .sp
313     /i REG_ICASE
314     /m REG_NEWLINE
315     /N REG_NOSUB
316     /s REG_DOTALL )
317 ph10 535 /U REG_UNGREEDY ) These options are not part of
318 ph10 518 /W REG_UCP ) the POSIX standard
319     /8 REG_UTF8 )
320     .sp
321     The \fB/+\fP modifier works as described above. All other modifiers are
322     ignored.
323     .
324     .
325 nigel 75 .SH "DATA LINES"
326 nigel 63 .rs
327     .sp
328 nigel 75 Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
329     whitespace is removed, and it is then scanned for \e escapes. Some of these are
330 nigel 63 pretty esoteric features, intended for checking out some of the more
331     complicated features of PCRE. If you are just testing "ordinary" regular
332     expressions, you probably don't need any of these. The following escapes are
333 nigel 53 recognized:
334 nigel 75 .sp
335 nigel 93 \ea alarm (BEL, \ex07)
336     \eb backspace (\ex08)
337     \ee escape (\ex27)
338     \ef formfeed (\ex0c)
339     \en newline (\ex0a)
340 nigel 91 .\" JOIN
341     \eqdd set the PCRE_MATCH_LIMIT limit to dd
342     (any number of digits)
343 nigel 93 \er carriage return (\ex0d)
344     \et tab (\ex09)
345     \ev vertical tab (\ex0b)
346 nigel 75 \ennn octal character (up to 3 octal digits)
347     \exhh hexadecimal character (up to 2 hex digits)
348     .\" JOIN
349     \ex{hh...} hexadecimal character, any number of digits
350 nigel 63 in UTF-8 mode
351 nigel 91 .\" JOIN
352 nigel 75 \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
353 nigel 91 or \fBpcre_dfa_exec()\fP
354     .\" JOIN
355 nigel 75 \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
356 nigel 91 or \fBpcre_dfa_exec()\fP
357 nigel 75 .\" JOIN
358     \eCdd call pcre_copy_substring() for substring dd
359     after a successful match (number less than 32)
360     .\" JOIN
361     \eCname call pcre_copy_named_substring() for substring
362 nigel 63 "name" after a successful match (name termin-
363     ated by next non alphanumeric character)
364 nigel 75 .\" JOIN
365     \eC+ show the current captured substrings at callout
366 nigel 63 time
367 nigel 75 \eC- do not supply a callout function
368     .\" JOIN
369     \eC!n return 1 instead of 0 when callout number n is
370 nigel 63 reached
371 nigel 75 .\" JOIN
372     \eC!n!m return 1 instead of 0 when callout number n is
373 nigel 63 reached for the nth time
374 nigel 75 .\" JOIN
375     \eC*n pass the number n (may be negative) as callout
376     data; this is used as the callout return value
377 nigel 77 \eD use the \fBpcre_dfa_exec()\fP match function
378     \eF only shortest match for \fBpcre_dfa_exec()\fP
379 nigel 75 .\" JOIN
380     \eGdd call pcre_get_substring() for substring dd
381     after a successful match (number less than 32)
382     .\" JOIN
383     \eGname call pcre_get_named_substring() for substring
384 nigel 63 "name" after a successful match (name termin-
385     ated by next non-alphanumeric character)
386 nigel 75 .\" JOIN
387     \eL call pcre_get_substringlist() after a
388 nigel 63 successful match
389 nigel 91 .\" JOIN
390 nigel 87 \eM discover the minimum MATCH_LIMIT and
391     MATCH_LIMIT_RECURSION settings
392 nigel 91 .\" JOIN
393 nigel 75 \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
394 ph10 442 or \fBpcre_dfa_exec()\fP; if used twice, pass the
395 ph10 461 PCRE_NOTEMPTY_ATSTART option
396 nigel 75 .\" JOIN
397     \eOdd set the size of the output vector passed to
398     \fBpcre_exec()\fP to dd (any number of digits)
399 nigel 77 .\" JOIN
400 ph10 428 \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP
401     or \fBpcre_dfa_exec()\fP; if used twice, pass the
402 ph10 461 PCRE_PARTIAL_HARD option
403 nigel 91 .\" JOIN
404     \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
405     (any number of digits)
406 nigel 77 \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
407 nigel 75 \eS output details of memory get/free calls during matching
408 nigel 91 .\" JOIN
409 ph10 455 \eY pass the PCRE_NO_START_OPTIMIZE option to \fBpcre_exec()\fP
410     or \fBpcre_dfa_exec()\fP
411     .\" JOIN
412 nigel 75 \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
413 nigel 91 or \fBpcre_dfa_exec()\fP
414 nigel 75 .\" JOIN
415     \e? pass the PCRE_NO_UTF8_CHECK option to
416 nigel 91 \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
417     .\" JOIN
418 ph10 567 \e>dd start the match at offset dd (optional "-"; then
419     any number of digits); this sets the \fIstartoffset\fP
420     argument for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
421 nigel 91 .\" JOIN
422     \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
423     or \fBpcre_dfa_exec()\fP
424     .\" JOIN
425     \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
426     or \fBpcre_dfa_exec()\fP
427     .\" JOIN
428     \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
429     or \fBpcre_dfa_exec()\fP
430 nigel 93 .\" JOIN
431 ph10 149 \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
432     or \fBpcre_dfa_exec()\fP
433     .\" JOIN
434 nigel 93 \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
435     or \fBpcre_dfa_exec()\fP
436 nigel 75 .sp
437 nigel 93 The escapes that specify line ending sequences are literal strings, exactly as
438     shown. No more than one newline setting should be present in any data line.
439 nigel 75 .P
440 nigel 93 A backslash followed by anything else just escapes the anything else. If
441     the very last character is a backslash, it is ignored. This gives a way of
442     passing an empty line as data, since a real empty line terminates the data
443     input.
444     .P
445 nigel 75 If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
446 nigel 87 different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
447     fields of the \fBpcre_extra\fP data structure, until it finds the minimum
448     numbers for each parameter that allow \fBpcre_exec()\fP to complete. The
449     \fImatch_limit\fP number is a measure of the amount of backtracking that takes
450     place, and checking it out can be instructive. For most simple matches, the
451     number is quite small, but for patterns with very large numbers of matching
452     possibilities, it can become large very quickly with increasing length of
453     subject string. The \fImatch_limit_recursion\fP number is a measure of how much
454     stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is needed
455     to complete the match attempt.
456 nigel 75 .P
457     When \eO is used, the value specified may be higher or lower than the size set
458     by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
459     the call of \fBpcre_exec()\fP for the line in which it appears.
460     .P
461     If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
462 ph10 518 API to be used, the only option-setting sequences that have any effect are \eB,
463     \eN, and \eZ, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
464     to be passed to \fBregexec()\fP.
465 nigel 75 .P
466     The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
467     of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
468 nigel 53 any number of hexadecimal digits inside the braces. The result is from one to
469 ph10 211 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
470     allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
471     valid Unicode code points, or indeed valid UTF-8 characters according to the
472     later rules in RFC 3629.
473 nigel 75 .
474     .
475 nigel 77 .SH "THE ALTERNATIVE MATCHING FUNCTION"
476 nigel 63 .rs
477     .sp
478 nigel 77 By default, \fBpcretest\fP uses the standard PCRE matching function,
479     \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
480     alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
481     different way, and has some restrictions. The differences between the two
482     functions are described in the
483     .\" HREF
484     \fBpcrematching\fP
485     .\"
486     documentation.
487     .P
488     If a data line contains the \eD escape sequence, or if the command line
489     contains the \fB-dfa\fP option, the alternative matching function is called.
490     This function finds all possible matches at a given point. If, however, the \eF
491     escape sequence is present in the data line, it stops after the first match is
492     found. This is always the shortest possible match.
493     .
494     .
495     .SH "DEFAULT OUTPUT FROM PCRETEST"
496     .rs
497     .sp
498     This section describes the output when the normal matching function,
499     \fBpcre_exec()\fP, is being used.
500     .P
501 nigel 53 When a match succeeds, pcretest outputs the list of captured substrings that
502 nigel 75 \fBpcre_exec()\fP returns, starting with number 0 for the string that matched
503 ph10 435 the whole pattern. Otherwise, it outputs "No match" when the return is
504     PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
505 ph10 553 substring when \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL. (Note that this is
506     the entire substring that was inspected during the partial match; it may
507     include characters before the actual match start if a lookbehind assertion,
508     \eK, \eb, or \eB was involved.) For any other returns, it outputs the PCRE
509     negative error number. Here is an example of an interactive \fBpcretest\fP run.
510 nigel 75 .sp
511 nigel 53 $ pcretest
512 nigel 93 PCRE version 7.0 30-Nov-2006
513 nigel 75 .sp
514     re> /^abc(\ed+)/
515 nigel 53 data> abc123
516     0: abc123
517     1: 123
518     data> xyz
519     No match
520 nigel 75 .sp
521 ph10 286 Note that unset capturing substrings that are not followed by one that is set
522 ph10 273 are not returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In
523     the following example, there are two capturing substrings, but when the first
524 ph10 286 data line is matched, the second, unset substring is not shown. An "internal"
525 ph10 273 unset substring is shown as "<unset>", as for the second data line.
526     .sp
527     re> /(a)|(b)/
528     data> a
529     0: a
530     1: a
531     data> b
532     0: b
533     1: <unset>
534 ph10 286 2: b
535 ph10 273 .sp
536 nigel 75 If the strings contain any non-printing characters, they are output as \e0x
537     escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
538 nigel 93 pattern. See below for the definition of non-printing characters. If the
539     pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
540     the the rest of the subject string, identified by "0+" like this:
541 nigel 75 .sp
542 nigel 53 re> /cat/+
543     data> cataract
544     0: cat
545     0+ aract
546 nigel 75 .sp
547     If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
548 nigel 53 matching attempts are output in sequence, like this:
549 nigel 75 .sp
550     re> /\eBi(\ew\ew)/g
551 nigel 53 data> Mississippi
552     0: iss
553     1: ss
554     0: iss
555     1: ss
556     0: ipp
557     1: pp
558 nigel 75 .sp
559 nigel 53 "No match" is output only if the first match attempt fails.
560 nigel 75 .P
561     If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
562 nigel 53 data line that is successfully matched, the substrings extracted by the
563     convenience functions are output with C, G, or L after the string number
564     instead of a colon. This is in addition to the normal full list. The string
565     length (that is, the return from the extraction function) is given in
566 nigel 75 parentheses after each string for \fB\eC\fP and \fB\eG\fP.
567     .P
568 nigel 93 Note that whereas patterns can be continued over several lines (a plain ">"
569 nigel 53 prompt is used for continuations), data lines may not. However newlines can be
570 nigel 93 included in data by means of the \en escape (or \er, \er\en, etc., depending on
571     the newline sequence setting).
572 nigel 75 .
573     .
574 nigel 93 .
575 nigel 77 .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
576     .rs
577     .sp
578     When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
579     means of the \eD escape sequence or the \fB-dfa\fP command line option), the
580     output consists of a list of all the matches that start at the first point in
581     the subject where there is at least one match. For example:
582     .sp
583     re> /(tang|tangerine|tan)/
584     data> yellow tangerine\eD
585     0: tangerine
586     1: tang
587     2: tan
588     .sp
589     (Using the normal matching function on this data finds only "tang".) The
590 ph10 428 longest matching string is always given first (and numbered zero). After a
591 ph10 461 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
592 ph10 553 partially matching substring. (Note that this is the entire substring that was
593     inspected during the partial match; it may include characters before the actual
594     match start if a lookbehind assertion, \eK, \eb, or \eB was involved.)
595 nigel 77 .P
596 nigel 93 If \fB/g\fP is present on the pattern, the search for further matches resumes
597 nigel 77 at the end of the longest match. For example:
598     .sp
599     re> /(tang|tangerine|tan)/g
600     data> yellow tangerine and tangy sultana\eD
601     0: tangerine
602     1: tang
603     2: tan
604     0: tang
605     1: tan
606     0: tan
607     .sp
608     Since the matching function does not support substring capture, the escape
609     sequences that are concerned with captured substrings are not relevant.
610     .
611     .
612     .SH "RESTARTING AFTER A PARTIAL MATCH"
613     .rs
614     .sp
615     When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
616     indicating that the subject partially matched the pattern, you can restart the
617     match with additional subject data by means of the \eR escape sequence. For
618     example:
619     .sp
620 ph10 155 re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
621 nigel 77 data> 23ja\eP\eD
622     Partial match: 23ja
623     data> n05\eR\eD
624     0: n05
625     .sp
626     For further information about partial matching, see the
627     .\" HREF
628     \fBpcrepartial\fP
629     .\"
630     documentation.
631     .
632     .
633 nigel 75 .SH CALLOUTS
634     .rs
635     .sp
636     If the pattern contains any callout requests, \fBpcretest\fP's callout function
637 nigel 77 is called during matching. This works with both matching functions. By default,
638     the called function displays the callout number, the start and current
639     positions in the text at the callout time, and the next pattern item to be
640     tested. For example, the output
641 nigel 75 .sp
642     --->pqrabcdef
643     0 ^ ^ \ed
644     .sp
645     indicates that callout number 0 occurred for a match attempt starting at the
646     fourth character of the subject string, when the pointer was at the seventh
647     character of the data, and when the next pattern item was \ed. Just one
648     circumflex is output if the start and current positions are the same.
649     .P
650     Callouts numbered 255 are assumed to be automatic callouts, inserted as a
651     result of the \fB/C\fP pattern modifier. In this case, instead of showing the
652     callout number, the offset in the pattern, preceded by a plus, is output. For
653     example:
654     .sp
655     re> /\ed?[A-E]\e*/C
656     data> E*
657     --->E*
658     +0 ^ \ed?
659     +3 ^ [A-E]
660     +8 ^^ \e*
661     +10 ^ ^
662     0: E*
663     .sp
664     The callout function in \fBpcretest\fP returns zero (carry on matching) by
665 nigel 77 default, but you can use a \eC item in a data line (as described above) to
666 nigel 75 change this.
667     .P
668     Inserting callouts can be helpful when using \fBpcretest\fP to check
669     complicated regular expressions. For further information about callouts, see
670     the
671     .\" HREF
672     \fBpcrecallout\fP
673     .\"
674     documentation.
675     .
676     .
677 nigel 93 .
678     .SH "NON-PRINTING CHARACTERS"
679     .rs
680     .sp
681     When \fBpcretest\fP is outputting text in the compiled version of a pattern,
682     bytes other than 32-126 are always treated as non-printing characters are are
683     therefore shown as hex escapes.
684     .P
685     When \fBpcretest\fP is outputting text that is a matched part of a subject
686     string, it behaves in the same way, unless a different locale has been set for
687     the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
688     function to distinguish printing and non-printing characters.
689     .
690     .
691     .
692 nigel 75 .SH "SAVING AND RELOADING COMPILED PATTERNS"
693     .rs
694     .sp
695     The facilities described in this section are not available when the POSIX
696     inteface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
697     specified.
698     .P
699     When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
700     compiled pattern to a file, by following the modifiers with > and a file name.
701     For example:
702     .sp
703     /pattern/im >/some/file
704     .sp
705     See the
706     .\" HREF
707     \fBpcreprecompile\fP
708     .\"
709     documentation for a discussion about saving and re-using compiled patterns.
710     .P
711     The data that is written is binary. The first eight bytes are the length of the
712     compiled pattern data followed by the length of the optional study data, each
713     written as four bytes in big-endian order (most significant byte first). If
714     there is no study data (either the pattern was not studied, or studying did not
715     return any data), the second length is zero. The lengths are followed by an
716     exact copy of the compiled pattern. If there is additional study data, this
717     follows immediately after the compiled pattern. After writing the file,
718     \fBpcretest\fP expects to read a new pattern.
719     .P
720     A saved pattern can be reloaded into \fBpcretest\fP by specifing < and a file
721     name instead of a pattern. The name of the file must not contain a < character,
722     as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
723     characters.
724     For example:
725     .sp
726     re> </some/file
727     Compiled regex loaded from /some/file
728     No study data
729     .sp
730     When the pattern has been loaded, \fBpcretest\fP proceeds to read data lines in
731     the usual way.
732     .P
733     You can copy a file written by \fBpcretest\fP to a different host and reload it
734     there, even if the new host has opposite endianness to the one on which the
735     pattern was compiled. For example, you can compile on an i86 machine and run on
736     a SPARC machine.
737     .P
738     File names for saving and reloading can be absolute or relative, but note that
739     the shell facility of expanding a file name that starts with a tilde (~) is not
740     available.
741     .P
742     The ability to save and reload files in \fBpcretest\fP is intended for testing
743     and experimentation. It is not intended for production use because only a
744     single pattern can be written to a file. Furthermore, there is no facility for
745     supplying custom character tables for use with a reloaded pattern. If the
746     original pattern was compiled with custom tables, an attempt to match a subject
747     string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
748     Finally, if you attempt to load a file that is not in the correct format, the
749     result is undefined.
750     .
751     .
752 nigel 93 .SH "SEE ALSO"
753     .rs
754     .sp
755     \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrematching\fP(3),
756 ph10 148 \fBpcrepartial\fP(d), \fBpcrepattern\fP(3), \fBpcreprecompile\fP(3).
757 nigel 93 .
758     .
759 nigel 53 .SH AUTHOR
760 nigel 63 .rs
761     .sp
762 ph10 99 .nf
763 nigel 77 Philip Hazel
764 ph10 99 University Computing Service
765 nigel 93 Cambridge CB2 3QH, England.
766 ph10 99 .fi
767     .
768     .
769     .SH REVISION
770     .rs
771     .sp
772     .nf
773 ph10 567 Last updated: 06 November 2010
774 ph10 510 Copyright (c) 1997-2010 University of Cambridge.
775 ph10 99 .fi

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