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1 nigel 53 .TH PCRETEST 1
2     .SH NAME
3     pcretest - a program for testing Perl-compatible regular expressions.
5     .B pcretest "[-d] [-i] [-m] [-o osize] [-p] [-t] [source] [destination]"
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 man page describes the features of the test program; for
10     details of the regular expressions themselves, see the \fBpcre\fR man page.
12     .SH OPTIONS
13     .TP 10
14     \fB-d\fR
15     Behave as if each regex had the \fB/D\fR modifier (see below); the internal
16     form is output after compilation.
17     .TP 10
18     \fB-i\fR
19     Behave as if each regex had the \fB/I\fR modifier; information about the
20     compiled pattern is given after compilation.
21     .TP 10
22     \fB-m\fR
23     Output the size of each compiled pattern after it has been compiled. This is
24     equivalent to adding /M to each regular expression. For compatibility with
25     earlier versions of pcretest, \fB-s\fR is a synonym for \fB-m\fR.
26     .TP 10
27     \fB-o\fR \fIosize\fR
28     Set the number of elements in the output vector that is used when calling PCRE
29     to be \fIosize\fR. The default value is 45, which is enough for 14 capturing
30     subexpressions. The vector size can be changed for individual matching calls by
31     including \\O in the data line (see below).
32     .TP 10
33     \fB-p\fR
34     Behave as if each regex has \fB/P\fR modifier; the POSIX wrapper API is used
35     to call PCRE. None of the other options has any effect when \fB-p\fR is set.
36     .TP 10
37     \fB-t\fR
38     Run each compile, study, and match 20000 times with a timer, and output
39     resulting time per compile or match (in milliseconds). Do not set \fB-t\fR with
40     \fB-m\fR, because you will then get the size output 20000 times and the timing
41     will be distorted.
46     If \fBpcretest\fR is given two filename arguments, it reads from the first and
47     writes to the second. If it is given only one filename argument, it reads from
48     that file and writes to stdout. Otherwise, it reads from stdin and writes to
49     stdout, and prompts for each line of input, using "re>" to prompt for regular
50     expressions, and "data>" to prompt for data lines.
52     The program handles any number of sets of input on a single input file. Each
53     set starts with a regular expression, and continues with any number of data
54     lines to be matched against the pattern. An empty line signals the end of the
55     data lines, at which point a new regular expression is read. The regular
56     expressions are given enclosed in any non-alphameric delimiters other than
57     backslash, for example
59     /(a|bc)x+yz/
61     White space before the initial delimiter is ignored. A regular expression may
62     be continued over several input lines, in which case the newline characters are
63     included within it. It is possible to include the delimiter within the pattern
64     by escaping it, for example
66     /abc\\/def/
68     If you do so, the escape and the delimiter form part of the pattern, but since
69     delimiters are always non-alphameric, this does not affect its interpretation.
70     If the terminating delimiter is immediately followed by a backslash, for
71     example,
73     /abc/\\
75     then a backslash is added to the end of the pattern. This is done to provide a
76     way of testing the error condition that arises if a pattern finishes with a
77     backslash, because
79     /abc\\/
81     is interpreted as the first line of a pattern that starts with "abc/", causing
82     pcretest to read the next line as a continuation of the regular expression.
87     The pattern may be followed by \fBi\fR, \fBm\fR, \fBs\fR, or \fBx\fR to set the
89     respectively. For example:
91     /caseless/i
93     These modifier letters have the same effect as they do in Perl. There are
94     others which set PCRE options that do not correspond to anything in Perl:
95     \fB/A\fR, \fB/E\fR, and \fB/X\fR set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and
96     PCRE_EXTRA respectively.
98     Searching for all possible matches within each subject string can be requested
99     by the \fB/g\fR or \fB/G\fR modifier. After finding a match, PCRE is called
100     again to search the remainder of the subject string. The difference between
101     \fB/g\fR and \fB/G\fR is that the former uses the \fIstartoffset\fR argument to
102     \fBpcre_exec()\fR to start searching at a new point within the entire string
103     (which is in effect what Perl does), whereas the latter passes over a shortened
104     substring. This makes a difference to the matching process if the pattern
105     begins with a lookbehind assertion (including \\b or \\B).
107     If any call to \fBpcre_exec()\fR in a \fB/g\fR or \fB/G\fR sequence matches an
108     empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
109     flags set in order to search for another, non-empty, match at the same point.
110     If this second match fails, the start offset is advanced by one, and the normal
111     match is retried. This imitates the way Perl handles such cases when using the
112     \fB/g\fR modifier or the \fBsplit()\fR function.
114     There are a number of other modifiers for controlling the way \fBpcretest\fR
115     operates.
117     The \fB/+\fR modifier requests that as well as outputting the substring that
118     matched the entire pattern, pcretest should in addition output the remainder of
119     the subject string. This is useful for tests where the subject contains
120     multiple copies of the same substring.
122     The \fB/L\fR modifier must be followed directly by the name of a locale, for
123     example,
125     /pattern/Lfr
127     For this reason, it must be the last modifier letter. The given locale is set,
128     \fBpcre_maketables()\fR is called to build a set of character tables for the
129     locale, and this is then passed to \fBpcre_compile()\fR when compiling the
130     regular expression. Without an \fB/L\fR modifier, NULL is passed as the tables
131     pointer; that is, \fB/L\fR applies only to the expression on which it appears.
133     The \fB/I\fR modifier requests that \fBpcretest\fR output information about the
134     compiled expression (whether it is anchored, has a fixed first character, and
135     so on). It does this by calling \fBpcre_fullinfo()\fR after compiling an
136     expression, and outputting the information it gets back. If the pattern is
137     studied, the results of that are also output.
139     The \fB/D\fR modifier is a PCRE debugging feature, which also assumes \fB/I\fR.
140     It causes the internal form of compiled regular expressions to be output after
141     compilation.
143     The \fB/S\fR modifier causes \fBpcre_study()\fR to be called after the
144     expression has been compiled, and the results used when the expression is
145     matched.
147     The \fB/M\fR modifier causes the size of memory block used to hold the compiled
148     pattern to be output.
150     The \fB/P\fR modifier causes \fBpcretest\fR to call PCRE via the POSIX wrapper
151     API rather than its native API. When this is done, all other modifiers except
152     \fB/i\fR, \fB/m\fR, and \fB/+\fR are ignored. REG_ICASE is set if \fB/i\fR is
153     present, and REG_NEWLINE is set if \fB/m\fR is present. The wrapper functions
154     force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
156     The \fB/8\fR modifier causes \fBpcretest\fR to call PCRE with the PCRE_UTF8
157     option set. This turns on the (currently incomplete) support for UTF-8
158     character handling in PCRE, provided that it was compiled with this support
159     enabled. This modifier also causes any non-printing characters in output
160     strings to be printed using the \\x{hh...} notation if they are valid UTF-8
161     sequences.
164     .SH DATA LINES
166     Before each data line is passed to \fBpcre_exec()\fR, leading and trailing
167     whitespace is removed, and it is then scanned for \\ escapes. The following are
168     recognized:
170     \\a alarm (= BEL)
171     \\b backspace
172     \\e escape
173     \\f formfeed
174     \\n newline
175     \\r carriage return
176     \\t tab
177     \\v vertical tab
178     \\nnn octal character (up to 3 octal digits)
179     \\xhh hexadecimal character (up to 2 hex digits)
180     \\x{hh...} hexadecimal UTF-8 character
182     \\A pass the PCRE_ANCHORED option to \fBpcre_exec()\fR
183     \\B pass the PCRE_NOTBOL option to \fBpcre_exec()\fR
184     \\Cdd call pcre_copy_substring() for substring dd
185     after a successful match (any decimal number
186     less than 32)
187     \\Gdd call pcre_get_substring() for substring dd
188     after a successful match (any decimal number
189     less than 32)
190     \\L call pcre_get_substringlist() after a
191     successful match
192     \\N pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fR
193     \\Odd set the size of the output vector passed to
194     \fBpcre_exec()\fR to dd (any number of decimal
195     digits)
196     \\Z pass the PCRE_NOTEOL option to \fBpcre_exec()\fR
198     When \\O is used, it may be higher or lower than the size set by the \fB-O\fR
199     option (or defaulted to 45); \\O applies only to the call of \fBpcre_exec()\fR
200     for the line in which it appears.
202     A backslash followed by anything else just escapes the anything else. If the
203     very last character is a backslash, it is ignored. This gives a way of passing
204     an empty line as data, since a real empty line terminates the data input.
206     If \fB/P\fR was present on the regex, causing the POSIX wrapper API to be used,
207     only \fB\B\fR, and \fB\Z\fR have any effect, causing REG_NOTBOL and REG_NOTEOL
208     to be passed to \fBregexec()\fR respectively.
210     The use of \\x{hh...} to represent UTF-8 characters is not dependent on the use
211     of the \fB/8\fR modifier on the pattern. It is recognized always. There may be
212     any number of hexadecimal digits inside the braces. The result is from one to
213     six bytes, encoded according to the UTF-8 rules.
218     When a match succeeds, pcretest outputs the list of captured substrings that
219     \fBpcre_exec()\fR returns, starting with number 0 for the string that matched
220     the whole pattern. Here is an example of an interactive pcretest run.
222     $ pcretest
223     PCRE version 2.06 08-Jun-1999
225     re> /^abc(\\d+)/
226     data> abc123
227     0: abc123
228     1: 123
229     data> xyz
230     No match
232     If the strings contain any non-printing characters, they are output as \\0x
233     escapes, or as \\x{...} escapes if the \fB/8\fR modifier was present on the
234     pattern. If the pattern has the \fB/+\fR modifier, then the output for
235     substring 0 is followed by the the rest of the subject string, identified by
236     "0+" like this:
238     re> /cat/+
239     data> cataract
240     0: cat
241     0+ aract
243     If the pattern has the \fB/g\fR or \fB/G\fR modifier, the results of successive
244     matching attempts are output in sequence, like this:
246     re> /\\Bi(\\w\\w)/g
247     data> Mississippi
248     0: iss
249     1: ss
250     0: iss
251     1: ss
252     0: ipp
253     1: pp
255     "No match" is output only if the first match attempt fails.
257     If any of the sequences \fB\\C\fR, \fB\\G\fR, or \fB\\L\fR are present in a
258     data line that is successfully matched, the substrings extracted by the
259     convenience functions are output with C, G, or L after the string number
260     instead of a colon. This is in addition to the normal full list. The string
261     length (that is, the return from the extraction function) is given in
262     parentheses after each string for \fB\\C\fR and \fB\\G\fR.
264     Note that while patterns can be continued over several lines (a plain ">"
265     prompt is used for continuations), data lines may not. However newlines can be
266     included in data by means of the \\n escape.
269     .SH AUTHOR
270     Philip Hazel <ph10@cam.ac.uk>
271     .br
272     University Computing Service,
273     .br
274     New Museums Site,
275     .br
276     Cambridge CB2 3QG, England.
277     .br
278     Phone: +44 1223 334714
280     Last updated: 15 August 2001
281     .br
282     Copyright (c) 1997-2001 University of Cambridge.

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