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1 .TH PCRETEST 1
2 .SH NAME
3 pcretest - a program for testing Perl-compatible regular expressions.
4 .SH SYNOPSIS
5 .B pcretest "[-d] [-i] [-m] [-o osize] [-p] [-t] [source] [destination]"
6
7 \fBpcretest\fR was written as a test program for the PCRE regular expression
8 library itself, but it can also be used for experimenting with regular
9 expressions. This document describes the features of the test program; for
10 details of the regular expressions themselves, see the
11 .\" HREF
12 \fBpcrepattern\fR
13 .\"
14 documentation. For details of PCRE and its options, see the
15 .\" HREF
16 \fBpcreapi\fR
17 .\"
18 documentation.
19
20 .SH OPTIONS
21 .rs
22 .sp
23 .TP 10
24 \fB-C\fR
25 Output the version number of the PCRE library, and all available information
26 about the optional features that are included, and then exit.
27 .TP 10
28 \fB-d\fR
29 Behave as if each regex had the \fB/D\fR modifier (see below); the internal
30 form is output after compilation.
31 .TP 10
32 \fB-i\fR
33 Behave as if each regex had the \fB/I\fR modifier; information about the
34 compiled pattern is given after compilation.
35 .TP 10
36 \fB-m\fR
37 Output the size of each compiled pattern after it has been compiled. This is
38 equivalent to adding /M to each regular expression. For compatibility with
39 earlier versions of pcretest, \fB-s\fR is a synonym for \fB-m\fR.
40 .TP 10
41 \fB-o\fR \fIosize\fR
42 Set the number of elements in the output vector that is used when calling PCRE
43 to be \fIosize\fR. The default value is 45, which is enough for 14 capturing
44 subexpressions. The vector size can be changed for individual matching calls by
45 including \\O in the data line (see below).
46 .TP 10
47 \fB-p\fR
48 Behave as if each regex has \fB/P\fR modifier; the POSIX wrapper API is used
49 to call PCRE. None of the other options has any effect when \fB-p\fR is set.
50 .TP 10
51 \fB-t\fR
52 Run each compile, study, and match many times with a timer, and output
53 resulting time per compile or match (in milliseconds). Do not set \fB-t\fR with
54 \fB-m\fR, because you will then get the size output 20000 times and the timing
55 will be distorted.
56
57 .SH DESCRIPTION
58 .rs
59 .sp
60 If \fBpcretest\fR is given two filename arguments, it reads from the first and
61 writes to the second. If it is given only one filename argument, it reads from
62 that file and writes to stdout. Otherwise, it reads from stdin and writes to
63 stdout, and prompts for each line of input, using "re>" to prompt for regular
64 expressions, and "data>" to prompt for data lines.
65
66 The program handles any number of sets of input on a single input file. Each
67 set starts with a regular expression, and continues with any number of data
68 lines to be matched against the pattern.
69
70 Each line is matched separately and independently. If you want to do
71 multiple-line matches, you have to use the \\n escape sequence in a single line
72 of input to encode the newline characters. The maximum length of data line is
73 30,000 characters.
74
75 An empty line signals the end of the data lines, at which point a new regular
76 expression is read. The regular expressions are given enclosed in any
77 non-alphameric delimiters other than backslash, for example
78
79 /(a|bc)x+yz/
80
81 White space before the initial delimiter is ignored. A regular expression may
82 be continued over several input lines, in which case the newline characters are
83 included within it. It is possible to include the delimiter within the pattern
84 by escaping it, for example
85
86 /abc\\/def/
87
88 If you do so, the escape and the delimiter form part of the pattern, but since
89 delimiters are always non-alphameric, this does not affect its interpretation.
90 If the terminating delimiter is immediately followed by a backslash, for
91 example,
92
93 /abc/\\
94
95 then a backslash is added to the end of the pattern. This is done to provide a
96 way of testing the error condition that arises if a pattern finishes with a
97 backslash, because
98
99 /abc\\/
100
101 is interpreted as the first line of a pattern that starts with "abc/", causing
102 pcretest to read the next line as a continuation of the regular expression.
103
104 .SH PATTERN MODIFIERS
105 .rs
106 .sp
107 The pattern may be followed by \fBi\fR, \fBm\fR, \fBs\fR, or \fBx\fR to set the
108 PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options,
109 respectively. For example:
110
111 /caseless/i
112
113 These modifier letters have the same effect as they do in Perl. There are
114 others which set PCRE options that do not correspond to anything in Perl:
115 \fB/A\fR, \fB/E\fR, and \fB/X\fR set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and
116 PCRE_EXTRA respectively.
117
118 Searching for all possible matches within each subject string can be requested
119 by the \fB/g\fR or \fB/G\fR modifier. After finding a match, PCRE is called
120 again to search the remainder of the subject string. The difference between
121 \fB/g\fR and \fB/G\fR is that the former uses the \fIstartoffset\fR argument to
122 \fBpcre_exec()\fR to start searching at a new point within the entire string
123 (which is in effect what Perl does), whereas the latter passes over a shortened
124 substring. This makes a difference to the matching process if the pattern
125 begins with a lookbehind assertion (including \\b or \\B).
126
127 If any call to \fBpcre_exec()\fR in a \fB/g\fR or \fB/G\fR sequence matches an
128 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
129 flags set in order to search for another, non-empty, match at the same point.
130 If this second match fails, the start offset is advanced by one, and the normal
131 match is retried. This imitates the way Perl handles such cases when using the
132 \fB/g\fR modifier or the \fBsplit()\fR function.
133
134 There are a number of other modifiers for controlling the way \fBpcretest\fR
135 operates.
136
137 The \fB/+\fR modifier requests that as well as outputting the substring that
138 matched the entire pattern, pcretest should in addition output the remainder of
139 the subject string. This is useful for tests where the subject contains
140 multiple copies of the same substring.
141
142 The \fB/L\fR modifier must be followed directly by the name of a locale, for
143 example,
144
145 /pattern/Lfr
146
147 For this reason, it must be the last modifier letter. The given locale is set,
148 \fBpcre_maketables()\fR is called to build a set of character tables for the
149 locale, and this is then passed to \fBpcre_compile()\fR when compiling the
150 regular expression. Without an \fB/L\fR modifier, NULL is passed as the tables
151 pointer; that is, \fB/L\fR applies only to the expression on which it appears.
152
153 The \fB/I\fR modifier requests that \fBpcretest\fR output information about the
154 compiled expression (whether it is anchored, has a fixed first character, and
155 so on). It does this by calling \fBpcre_fullinfo()\fR after compiling an
156 expression, and outputting the information it gets back. If the pattern is
157 studied, the results of that are also output.
158
159 The \fB/D\fR modifier is a PCRE debugging feature, which also assumes \fB/I\fR.
160 It causes the internal form of compiled regular expressions to be output after
161 compilation. If the pattern was studied, the information returned is also
162 output.
163
164 The \fB/S\fR modifier causes \fBpcre_study()\fR to be called after the
165 expression has been compiled, and the results used when the expression is
166 matched.
167
168 The \fB/M\fR modifier causes the size of memory block used to hold the compiled
169 pattern to be output.
170
171 The \fB/P\fR modifier causes \fBpcretest\fR to call PCRE via the POSIX wrapper
172 API rather than its native API. When this is done, all other modifiers except
173 \fB/i\fR, \fB/m\fR, and \fB/+\fR are ignored. REG_ICASE is set if \fB/i\fR is
174 present, and REG_NEWLINE is set if \fB/m\fR is present. The wrapper functions
175 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
176
177 The \fB/8\fR modifier causes \fBpcretest\fR to call PCRE with the PCRE_UTF8
178 option set. This turns on support for UTF-8 character handling in PCRE,
179 provided that it was compiled with this support enabled. This modifier also
180 causes any non-printing characters in output strings to be printed using the
181 \\x{hh...} notation if they are valid UTF-8 sequences.
182
183 .SH CALLOUTS
184 .rs
185 .sp
186 If the pattern contains any callout requests, \fBpcretest\fR's callout function
187 will be called. By default, it displays the callout number, and the start and
188 current positions in the text at the callout time. For example, the output
189
190 --->pqrabcdef
191 0 ^ ^
192
193 indicates that callout number 0 occurred for a match attempt starting at the
194 fourth character of the subject string, when the pointer was at the seventh
195 character. The callout function returns zero (carry on matching) by default.
196
197 Inserting callouts may be helpful when using \fBpcretest\fR to check
198 complicated regular expressions. For further information about callouts, see
199 the
200 .\" HREF
201 \fBpcrecallout\fR
202 .\"
203 documentation.
204
205 For testing the PCRE library, additional control of callout behaviour is
206 available via escape sequences in the data, as described in the following
207 section. In particular, it is possible to pass in a number as callout data (the
208 default is zero). If the callout function receives a non-zero number, it
209 returns that value instead of zero.
210
211 .SH DATA LINES
212 .rs
213 .sp
214 Before each data line is passed to \fBpcre_exec()\fR, leading and trailing
215 whitespace is removed, and it is then scanned for \\ escapes. Some of these are
216 pretty esoteric features, intended for checking out some of the more
217 complicated features of PCRE. If you are just testing "ordinary" regular
218 expressions, you probably don't need any of these. The following escapes are
219 recognized:
220
221 \\a alarm (= BEL)
222 \\b backspace
223 \\e escape
224 \\f formfeed
225 \\n newline
226 \\r carriage return
227 \\t tab
228 \\v vertical tab
229 \\nnn octal character (up to 3 octal digits)
230 \\xhh hexadecimal character (up to 2 hex digits)
231 \\x{hh...} hexadecimal character, any number of digits
232 in UTF-8 mode
233 \\A pass the PCRE_ANCHORED option to \fBpcre_exec()\fR
234 \\B pass the PCRE_NOTBOL option to \fBpcre_exec()\fR
235 \\Cdd call pcre_copy_substring() for substring dd
236 after a successful match (any decimal number
237 less than 32)
238 \\Cname call pcre_copy_named_substring() for substring
239 "name" after a successful match (name termin-
240 ated by next non alphanumeric character)
241 \\C+ show the current captured substrings at callout
242 time
243 \\C- do not supply a callout function
244 \\C!n return 1 instead of 0 when callout number n is
245 reached
246 \\C!n!m return 1 instead of 0 when callout number n is
247 reached for the nth time
248 \\C*n pass the number n (may be negative) as callout
249 data
250 \\Gdd call pcre_get_substring() for substring dd
251 after a successful match (any decimal number
252 less than 32)
253 \\Gname call pcre_get_named_substring() for substring
254 "name" after a successful match (name termin-
255 ated by next non-alphanumeric character)
256 \\L call pcre_get_substringlist() after a
257 successful match
258 \\M discover the minimum MATCH_LIMIT setting
259 \\N pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fR
260 \\Odd set the size of the output vector passed to
261 \fBpcre_exec()\fR to dd (any number of decimal
262 digits)
263 \\Z pass the PCRE_NOTEOL option to \fBpcre_exec()\fR
264
265 If \\M is present, \fBpcretest\fR calls \fBpcre_exec()\fR several times, with
266 different values in the \fImatch_limit\fR field of the \fBpcre_extra\fR data
267 structure, until it finds the minimum number that is needed for
268 \fBpcre_exec()\fR to complete. This number is a measure of the amount of
269 recursion and backtracking that takes place, and checking it out can be
270 instructive. For most simple matches, the number is quite small, but for
271 patterns with very large numbers of matching possibilities, it can become large
272 very quickly with increasing length of subject string.
273
274 When \\O is used, it may be higher or lower than the size set by the \fB-O\fR
275 option (or defaulted to 45); \\O applies only to the call of \fBpcre_exec()\fR
276 for the line in which it appears.
277
278 A backslash followed by anything else just escapes the anything else. If the
279 very last character is a backslash, it is ignored. This gives a way of passing
280 an empty line as data, since a real empty line terminates the data input.
281
282 If \fB/P\fR was present on the regex, causing the POSIX wrapper API to be used,
283 only \fB\B\fR, and \fB\Z\fR have any effect, causing REG_NOTBOL and REG_NOTEOL
284 to be passed to \fBregexec()\fR respectively.
285
286 The use of \\x{hh...} to represent UTF-8 characters is not dependent on the use
287 of the \fB/8\fR modifier on the pattern. It is recognized always. There may be
288 any number of hexadecimal digits inside the braces. The result is from one to
289 six bytes, encoded according to the UTF-8 rules.
290
291 .SH OUTPUT FROM PCRETEST
292 .rs
293 .sp
294 When a match succeeds, pcretest outputs the list of captured substrings that
295 \fBpcre_exec()\fR returns, starting with number 0 for the string that matched
296 the whole pattern. Here is an example of an interactive pcretest run.
297
298 $ pcretest
299 PCRE version 4.00 08-Jan-2003
300
301 re> /^abc(\\d+)/
302 data> abc123
303 0: abc123
304 1: 123
305 data> xyz
306 No match
307
308 If the strings contain any non-printing characters, they are output as \\0x
309 escapes, or as \\x{...} escapes if the \fB/8\fR modifier was present on the
310 pattern. If the pattern has the \fB/+\fR modifier, then the output for
311 substring 0 is followed by the the rest of the subject string, identified by
312 "0+" like this:
313
314 re> /cat/+
315 data> cataract
316 0: cat
317 0+ aract
318
319 If the pattern has the \fB/g\fR or \fB/G\fR modifier, the results of successive
320 matching attempts are output in sequence, like this:
321
322 re> /\\Bi(\\w\\w)/g
323 data> Mississippi
324 0: iss
325 1: ss
326 0: iss
327 1: ss
328 0: ipp
329 1: pp
330
331 "No match" is output only if the first match attempt fails.
332
333 If any of the sequences \fB\\C\fR, \fB\\G\fR, or \fB\\L\fR are present in a
334 data line that is successfully matched, the substrings extracted by the
335 convenience functions are output with C, G, or L after the string number
336 instead of a colon. This is in addition to the normal full list. The string
337 length (that is, the return from the extraction function) is given in
338 parentheses after each string for \fB\\C\fR and \fB\\G\fR.
339
340 Note that while patterns can be continued over several lines (a plain ">"
341 prompt is used for continuations), data lines may not. However newlines can be
342 included in data by means of the \\n escape.
343
344 .SH AUTHOR
345 .rs
346 .sp
347 Philip Hazel <ph10@cam.ac.uk>
348 .br
349 University Computing Service,
350 .br
351 Cambridge CB2 3QG, England.
352
353 .in 0
354 Last updated: 03 February 2003
355 .br
356 Copyright (c) 1997-2003 University of Cambridge.

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