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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     .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 nigel 63 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 nigel 53
20     .SH OPTIONS
21 nigel 63 .rs
22     .sp
23 nigel 53 .TP 10
24 nigel 63 \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 nigel 53 \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 nigel 63 Run each compile, study, and match many times with a timer, and output
53 nigel 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 nigel 63 .rs
59     .sp
60 nigel 53 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 nigel 63 lines to be matched against the pattern.
69 nigel 53
70 nigel 63 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 nigel 53 /(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 nigel 63 .rs
106     .sp
107 nigel 53 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 nigel 63 compilation. If the pattern was studied, the information returned is also
162     output.
163 nigel 53
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 nigel 63 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 nigel 53
183 nigel 63 .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 nigel 53
190 nigel 63 --->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 nigel 53 .SH DATA LINES
212 nigel 63 .rs
213     .sp
214 nigel 53 Before each data line is passed to \fBpcre_exec()\fR, leading and trailing
215 nigel 63 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 nigel 53 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 nigel 63 \\x{hh...} hexadecimal character, any number of digits
232     in UTF-8 mode
233 nigel 53 \\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 nigel 63 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 nigel 53 \\Gdd call pcre_get_substring() for substring dd
251 nigel 63 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 nigel 53 \\L call pcre_get_substringlist() after a
257 nigel 63 successful match
258     \\M discover the minimum MATCH_LIMIT setting
259 nigel 53 \\N pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fR
260     \\Odd set the size of the output vector passed to
261 nigel 63 \fBpcre_exec()\fR to dd (any number of decimal
262     digits)
263 nigel 53 \\Z pass the PCRE_NOTEOL option to \fBpcre_exec()\fR
264    
265 nigel 63 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 nigel 53 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 nigel 63 .rs
293     .sp
294 nigel 53 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 nigel 63 PCRE version 4.00 08-Jan-2003
300 nigel 53
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 nigel 63 .rs
346     .sp
347 nigel 53 Philip Hazel <ph10@cam.ac.uk>
348     .br
349     University Computing Service,
350     .br
351     Cambridge CB2 3QG, England.
352    
353 nigel 63 .in 0
354     Last updated: 03 February 2003
355 nigel 53 .br
356 nigel 63 Copyright (c) 1997-2003 University of Cambridge.

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