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1 <HTML>
2 <HEAD>
3 <TITLE>pcretest specification</TITLE>
4 </HEAD>
5 <body bgcolor="#FFFFFF" text="#00005A">
6 <H1>pcretest specification</H1>
7 This HTML document has been generated automatically from the original man page.
8 If there is any nonsense in it, please consult the man page in case the
9 conversion went wrong.
10 <UL>
19 </UL>
21 <P>
22 pcretest - a program for testing Perl-compatible regular expressions.
23 </P>
25 <P>
26 <B>pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [source] [destination]</B>
27 </P>
28 <P>
29 <B>pcretest</B> was written as a test program for the PCRE regular expression
30 library itself, but it can also be used for experimenting with regular
31 expressions. This man page describes the features of the test program; for
32 details of the regular expressions themselves, see the <B>pcre</B> man page.
33 </P>
35 <P>
36 <B>-d</B>
37 Behave as if each regex had the <B>/D</B> modifier (see below); the internal
38 form is output after compilation.
39 </P>
40 <P>
41 <B>-i</B>
42 Behave as if each regex had the <B>/I</B> modifier; information about the
43 compiled pattern is given after compilation.
44 </P>
45 <P>
46 <B>-m</B>
47 Output the size of each compiled pattern after it has been compiled. This is
48 equivalent to adding /M to each regular expression. For compatibility with
49 earlier versions of pcretest, <B>-s</B> is a synonym for <B>-m</B>.
50 </P>
51 <P>
52 <B>-o</B> <I>osize</I>
53 Set the number of elements in the output vector that is used when calling PCRE
54 to be <I>osize</I>. The default value is 45, which is enough for 14 capturing
55 subexpressions. The vector size can be changed for individual matching calls by
56 including \O in the data line (see below).
57 </P>
58 <P>
59 <B>-p</B>
60 Behave as if each regex has <B>/P</B> modifier; the POSIX wrapper API is used
61 to call PCRE. None of the other options has any effect when <B>-p</B> is set.
62 </P>
63 <P>
64 <B>-t</B>
65 Run each compile, study, and match 20000 times with a timer, and output
66 resulting time per compile or match (in milliseconds). Do not set <B>-t</B> with
67 <B>-m</B>, because you will then get the size output 20000 times and the timing
68 will be distorted.
69 </P>
71 <P>
72 If <B>pcretest</B> is given two filename arguments, it reads from the first and
73 writes to the second. If it is given only one filename argument, it reads from
74 that file and writes to stdout. Otherwise, it reads from stdin and writes to
75 stdout, and prompts for each line of input, using "re&#62;" to prompt for regular
76 expressions, and "data&#62;" to prompt for data lines.
77 </P>
78 <P>
79 The program handles any number of sets of input on a single input file. Each
80 set starts with a regular expression, and continues with any number of data
81 lines to be matched against the pattern. An empty line signals the end of the
82 data lines, at which point a new regular expression is read. The regular
83 expressions are given enclosed in any non-alphameric delimiters other than
84 backslash, for example
85 </P>
86 <P>
87 <PRE>
88 /(a|bc)x+yz/
89 </PRE>
90 </P>
91 <P>
92 White space before the initial delimiter is ignored. A regular expression may
93 be continued over several input lines, in which case the newline characters are
94 included within it. It is possible to include the delimiter within the pattern
95 by escaping it, for example
96 </P>
97 <P>
98 <PRE>
99 /abc\/def/
100 </PRE>
101 </P>
102 <P>
103 If you do so, the escape and the delimiter form part of the pattern, but since
104 delimiters are always non-alphameric, this does not affect its interpretation.
105 If the terminating delimiter is immediately followed by a backslash, for
106 example,
107 </P>
108 <P>
109 <PRE>
110 /abc/\
111 </PRE>
112 </P>
113 <P>
114 then a backslash is added to the end of the pattern. This is done to provide a
115 way of testing the error condition that arises if a pattern finishes with a
116 backslash, because
117 </P>
118 <P>
119 <PRE>
120 /abc\/
121 </PRE>
122 </P>
123 <P>
124 is interpreted as the first line of a pattern that starts with "abc/", causing
125 pcretest to read the next line as a continuation of the regular expression.
126 </P>
128 <P>
129 The pattern may be followed by <B>i</B>, <B>m</B>, <B>s</B>, or <B>x</B> to set the
131 respectively. For example:
132 </P>
133 <P>
134 <PRE>
135 /caseless/i
136 </PRE>
137 </P>
138 <P>
139 These modifier letters have the same effect as they do in Perl. There are
140 others which set PCRE options that do not correspond to anything in Perl:
141 <B>/A</B>, <B>/E</B>, and <B>/X</B> set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and
142 PCRE_EXTRA respectively.
143 </P>
144 <P>
145 Searching for all possible matches within each subject string can be requested
146 by the <B>/g</B> or <B>/G</B> modifier. After finding a match, PCRE is called
147 again to search the remainder of the subject string. The difference between
148 <B>/g</B> and <B>/G</B> is that the former uses the <I>startoffset</I> argument to
149 <B>pcre_exec()</B> to start searching at a new point within the entire string
150 (which is in effect what Perl does), whereas the latter passes over a shortened
151 substring. This makes a difference to the matching process if the pattern
152 begins with a lookbehind assertion (including \b or \B).
153 </P>
154 <P>
155 If any call to <B>pcre_exec()</B> in a <B>/g</B> or <B>/G</B> sequence matches an
156 empty string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
157 flags set in order to search for another, non-empty, match at the same point.
158 If this second match fails, the start offset is advanced by one, and the normal
159 match is retried. This imitates the way Perl handles such cases when using the
160 <B>/g</B> modifier or the <B>split()</B> function.
161 </P>
162 <P>
163 There are a number of other modifiers for controlling the way <B>pcretest</B>
164 operates.
165 </P>
166 <P>
167 The <B>/+</B> modifier requests that as well as outputting the substring that
168 matched the entire pattern, pcretest should in addition output the remainder of
169 the subject string. This is useful for tests where the subject contains
170 multiple copies of the same substring.
171 </P>
172 <P>
173 The <B>/L</B> modifier must be followed directly by the name of a locale, for
174 example,
175 </P>
176 <P>
177 <PRE>
178 /pattern/Lfr
179 </PRE>
180 </P>
181 <P>
182 For this reason, it must be the last modifier letter. The given locale is set,
183 <B>pcre_maketables()</B> is called to build a set of character tables for the
184 locale, and this is then passed to <B>pcre_compile()</B> when compiling the
185 regular expression. Without an <B>/L</B> modifier, NULL is passed as the tables
186 pointer; that is, <B>/L</B> applies only to the expression on which it appears.
187 </P>
188 <P>
189 The <B>/I</B> modifier requests that <B>pcretest</B> output information about the
190 compiled expression (whether it is anchored, has a fixed first character, and
191 so on). It does this by calling <B>pcre_fullinfo()</B> after compiling an
192 expression, and outputting the information it gets back. If the pattern is
193 studied, the results of that are also output.
194 </P>
195 <P>
196 The <B>/D</B> modifier is a PCRE debugging feature, which also assumes <B>/I</B>.
197 It causes the internal form of compiled regular expressions to be output after
198 compilation.
199 </P>
200 <P>
201 The <B>/S</B> modifier causes <B>pcre_study()</B> to be called after the
202 expression has been compiled, and the results used when the expression is
203 matched.
204 </P>
205 <P>
206 The <B>/M</B> modifier causes the size of memory block used to hold the compiled
207 pattern to be output.
208 </P>
209 <P>
210 The <B>/P</B> modifier causes <B>pcretest</B> to call PCRE via the POSIX wrapper
211 API rather than its native API. When this is done, all other modifiers except
212 <B>/i</B>, <B>/m</B>, and <B>/+</B> are ignored. REG_ICASE is set if <B>/i</B> is
213 present, and REG_NEWLINE is set if <B>/m</B> is present. The wrapper functions
214 force PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
215 </P>
216 <P>
217 The <B>/8</B> modifier causes <B>pcretest</B> to call PCRE with the PCRE_UTF8
218 option set. This turns on the (currently incomplete) support for UTF-8
219 character handling in PCRE, provided that it was compiled with this support
220 enabled. This modifier also causes any non-printing characters in output
221 strings to be printed using the \x{hh...} notation if they are valid UTF-8
222 sequences.
223 </P>
225 <P>
226 Before each data line is passed to <B>pcre_exec()</B>, leading and trailing
227 whitespace is removed, and it is then scanned for \ escapes. The following are
228 recognized:
229 </P>
230 <P>
231 <PRE>
232 \a alarm (= BEL)
233 \b backspace
234 \e escape
235 \f formfeed
236 \n newline
237 \r carriage return
238 \t tab
239 \v vertical tab
240 \nnn octal character (up to 3 octal digits)
241 \xhh hexadecimal character (up to 2 hex digits)
242 \x{hh...} hexadecimal UTF-8 character
243 </PRE>
244 </P>
245 <P>
246 <PRE>
247 \A pass the PCRE_ANCHORED option to <B>pcre_exec()</B>
248 \B pass the PCRE_NOTBOL option to <B>pcre_exec()</B>
249 \Cdd call pcre_copy_substring() for substring dd
250 after a successful match (any decimal number
251 less than 32)
252 \Gdd call pcre_get_substring() for substring dd
253 after a successful match (any decimal number
254 less than 32)
255 \L call pcre_get_substringlist() after a
256 successful match
257 \N pass the PCRE_NOTEMPTY option to <B>pcre_exec()</B>
258 \Odd set the size of the output vector passed to
259 <B>pcre_exec()</B> to dd (any number of decimal
260 digits)
261 \Z pass the PCRE_NOTEOL option to <B>pcre_exec()</B>
262 </PRE>
263 </P>
264 <P>
265 When \O is used, it may be higher or lower than the size set by the <B>-O</B>
266 option (or defaulted to 45); \O applies only to the call of <B>pcre_exec()</B>
267 for the line in which it appears.
268 </P>
269 <P>
270 A backslash followed by anything else just escapes the anything else. If the
271 very last character is a backslash, it is ignored. This gives a way of passing
272 an empty line as data, since a real empty line terminates the data input.
273 </P>
274 <P>
275 If <B>/P</B> was present on the regex, causing the POSIX wrapper API to be used,
276 only <B>\B</B>, and <B>\Z</B> have any effect, causing REG_NOTBOL and REG_NOTEOL
277 to be passed to <B>regexec()</B> respectively.
278 </P>
279 <P>
280 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
281 of the <B>/8</B> modifier on the pattern. It is recognized always. There may be
282 any number of hexadecimal digits inside the braces. The result is from one to
283 six bytes, encoded according to the UTF-8 rules.
284 </P>
286 <P>
287 When a match succeeds, pcretest outputs the list of captured substrings that
288 <B>pcre_exec()</B> returns, starting with number 0 for the string that matched
289 the whole pattern. Here is an example of an interactive pcretest run.
290 </P>
291 <P>
292 <PRE>
293 $ pcretest
294 PCRE version 2.06 08-Jun-1999
295 </PRE>
296 </P>
297 <P>
298 <PRE>
299 re&#62; /^abc(\d+)/
300 data&#62; abc123
301 0: abc123
302 1: 123
303 data&#62; xyz
304 No match
305 </PRE>
306 </P>
307 <P>
308 If the strings contain any non-printing characters, they are output as \0x
309 escapes, or as \x{...} escapes if the <B>/8</B> modifier was present on the
310 pattern. If the pattern has the <B>/+</B> 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 </P>
314 <P>
315 <PRE>
316 re&#62; /cat/+
317 data&#62; cataract
318 0: cat
319 0+ aract
320 </PRE>
321 </P>
322 <P>
323 If the pattern has the <B>/g</B> or <B>/G</B> modifier, the results of successive
324 matching attempts are output in sequence, like this:
325 </P>
326 <P>
327 <PRE>
328 re&#62; /\Bi(\w\w)/g
329 data&#62; Mississippi
330 0: iss
331 1: ss
332 0: iss
333 1: ss
334 0: ipp
335 1: pp
336 </PRE>
337 </P>
338 <P>
339 "No match" is output only if the first match attempt fails.
340 </P>
341 <P>
342 If any of the sequences <B>\C</B>, <B>\G</B>, or <B>\L</B> are present in a
343 data line that is successfully matched, the substrings extracted by the
344 convenience functions are output with C, G, or L after the string number
345 instead of a colon. This is in addition to the normal full list. The string
346 length (that is, the return from the extraction function) is given in
347 parentheses after each string for <B>\C</B> and <B>\G</B>.
348 </P>
349 <P>
350 Note that while patterns can be continued over several lines (a plain "&#62;"
351 prompt is used for continuations), data lines may not. However newlines can be
352 included in data by means of the \n escape.
353 </P>
355 <P>
356 Philip Hazel &#60;ph10@cam.ac.uk&#62;
357 <BR>
358 University Computing Service,
359 <BR>
360 New Museums Site,
361 <BR>
362 Cambridge CB2 3QG, England.
363 <BR>
364 Phone: +44 1223 334714
365 </P>
366 <P>
367 Last updated: 15 August 2001
368 <BR>
369 Copyright (c) 1997-2001 University of Cambridge.

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