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1 <html>
2 <head>
3 <title>pcretest specification</title>
4 </head>
5 <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6 <h1>pcretest man page</h1>
7 <p>
8 Return to the <a href="index.html">PCRE index page</a>.
9 </p>
10 <p>
11 This page is part of the PCRE HTML documentation. It was generated automatically
12 from the original man page. If there is any nonsense in it, please consult the
13 man page, in case the conversion went wrong.
14 <br>
15 <ul>
16 <li><a name="TOC1" href="#SEC1">SYNOPSIS</a>
17 <li><a name="TOC2" href="#SEC2">OPTIONS</a>
18 <li><a name="TOC3" href="#SEC3">DESCRIPTION</a>
19 <li><a name="TOC4" href="#SEC4">PATTERN MODIFIERS</a>
20 <li><a name="TOC5" href="#SEC5">DATA LINES</a>
21 <li><a name="TOC6" href="#SEC6">THE ALTERNATIVE MATCHING FUNCTION</a>
22 <li><a name="TOC7" href="#SEC7">DEFAULT OUTPUT FROM PCRETEST</a>
23 <li><a name="TOC8" href="#SEC8">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a>
24 <li><a name="TOC9" href="#SEC9">RESTARTING AFTER A PARTIAL MATCH</a>
25 <li><a name="TOC10" href="#SEC10">CALLOUTS</a>
26 <li><a name="TOC11" href="#SEC11">NON-PRINTING CHARACTERS</a>
27 <li><a name="TOC12" href="#SEC12">SAVING AND RELOADING COMPILED PATTERNS</a>
28 <li><a name="TOC13" href="#SEC13">SEE ALSO</a>
29 <li><a name="TOC14" href="#SEC14">AUTHOR</a>
30 <li><a name="TOC15" href="#SEC15">REVISION</a>
31 </ul>
32 <br><a name="SEC1" href="#TOC1">SYNOPSIS</a><br>
33 <P>
34 <b>pcretest [options] [source] [destination]</b>
35 <br>
36 <br>
37 <b>pcretest</b> was written as a test program for the PCRE regular expression
38 library itself, but it can also be used for experimenting with regular
39 expressions. This document describes the features of the test program; for
40 details of the regular expressions themselves, see the
41 <a href="pcrepattern.html"><b>pcrepattern</b></a>
42 documentation. For details of the PCRE library function calls and their
43 options, see the
44 <a href="pcreapi.html"><b>pcreapi</b></a>
45 documentation.
46 </P>
47 <br><a name="SEC2" href="#TOC1">OPTIONS</a><br>
48 <P>
49 <b>-b</b>
50 Behave as if each regex has the <b>/B</b> (show bytecode) modifier; the internal
51 form is output after compilation.
52 </P>
53 <P>
54 <b>-C</b>
55 Output the version number of the PCRE library, and all available information
56 about the optional features that are included, and then exit.
57 </P>
58 <P>
59 <b>-d</b>
60 Behave as if each regex has the <b>/D</b> (debug) modifier; the internal
61 form and information about the compiled pattern is output after compilation;
62 <b>-d</b> is equivalent to <b>-b -i</b>.
63 </P>
64 <P>
65 <b>-dfa</b>
66 Behave as if each data line contains the \D escape sequence; this causes the
67 alternative matching function, <b>pcre_dfa_exec()</b>, to be used instead of the
68 standard <b>pcre_exec()</b> function (more detail is given below).
69 </P>
70 <P>
71 <b>-help</b>
72 Output a brief summary these options and then exit.
73 </P>
74 <P>
75 <b>-i</b>
76 Behave as if each regex has the <b>/I</b> modifier; information about the
77 compiled pattern is given after compilation.
78 </P>
79 <P>
80 <b>-M</b>
81 Behave as if each data line contains the \M escape sequence; this causes
82 PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
83 calling <b>pcre_exec()</b> repeatedly with different limits.
84 </P>
85 <P>
86 <b>-m</b>
87 Output the size of each compiled pattern after it has been compiled. This is
88 equivalent to adding <b>/M</b> to each regular expression. For compatibility
89 with earlier versions of pcretest, <b>-s</b> is a synonym for <b>-m</b>.
90 </P>
91 <P>
92 <b>-o</b> <i>osize</i>
93 Set the number of elements in the output vector that is used when calling
94 <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> to be <i>osize</i>. The default value
95 is 45, which is enough for 14 capturing subexpressions for <b>pcre_exec()</b> or
96 22 different matches for <b>pcre_dfa_exec()</b>. The vector size can be
97 changed for individual matching calls by including \O in the data line (see
98 below).
99 </P>
100 <P>
101 <b>-p</b>
102 Behave as if each regex has the <b>/P</b> modifier; the POSIX wrapper API is
103 used to call PCRE. None of the other options has any effect when <b>-p</b> is
104 set.
105 </P>
106 <P>
107 <b>-q</b>
108 Do not output the version number of <b>pcretest</b> at the start of execution.
109 </P>
110 <P>
111 <b>-S</b> <i>size</i>
112 On Unix-like systems, set the size of the runtime stack to <i>size</i>
113 megabytes.
114 </P>
115 <P>
116 <b>-t</b>
117 Run each compile, study, and match many times with a timer, and output
118 resulting time per compile or match (in milliseconds). Do not set <b>-m</b> with
119 <b>-t</b>, because you will then get the size output a zillion times, and the
120 timing will be distorted. You can control the number of iterations that are
121 used for timing by following <b>-t</b> with a number (as a separate item on the
122 command line). For example, "-t 1000" would iterate 1000 times. The default is
123 to iterate 500000 times.
124 </P>
125 <P>
126 <b>-tm</b>
127 This is like <b>-t</b> except that it times only the matching phase, not the
128 compile or study phases.
129 </P>
130 <br><a name="SEC3" href="#TOC1">DESCRIPTION</a><br>
131 <P>
132 If <b>pcretest</b> is given two filename arguments, it reads from the first and
133 writes to the second. If it is given only one filename argument, it reads from
134 that file and writes to stdout. Otherwise, it reads from stdin and writes to
135 stdout, and prompts for each line of input, using "re&#62;" to prompt for regular
136 expressions, and "data&#62;" to prompt for data lines.
137 </P>
138 <P>
139 When <b>pcretest</b> is built, a configuration option can specify that it should
140 be linked with the <b>libreadline</b> library. When this is done, if the input
141 is from a terminal, it is read using the <b>readline()</b> function. This
142 provides line-editing and history facilities. The output from the <b>-help</b>
143 option states whether or not <b>readline()</b> will be used.
144 </P>
145 <P>
146 The program handles any number of sets of input on a single input file. Each
147 set starts with a regular expression, and continues with any number of data
148 lines to be matched against the pattern.
149 </P>
150 <P>
151 Each data line is matched separately and independently. If you want to do
152 multi-line matches, you have to use the \n escape sequence (or \r or \r\n,
153 etc., depending on the newline setting) in a single line of input to encode the
154 newline sequences. There is no limit on the length of data lines; the input
155 buffer is automatically extended if it is too small.
156 </P>
157 <P>
158 An empty line signals the end of the data lines, at which point a new regular
159 expression is read. The regular expressions are given enclosed in any
160 non-alphanumeric delimiters other than backslash, for example:
161 <pre>
162 /(a|bc)x+yz/
163 </pre>
164 White space before the initial delimiter is ignored. A regular expression may
165 be continued over several input lines, in which case the newline characters are
166 included within it. It is possible to include the delimiter within the pattern
167 by escaping it, for example
168 <pre>
169 /abc\/def/
170 </pre>
171 If you do so, the escape and the delimiter form part of the pattern, but since
172 delimiters are always non-alphanumeric, this does not affect its interpretation.
173 If the terminating delimiter is immediately followed by a backslash, for
174 example,
175 <pre>
176 /abc/\
177 </pre>
178 then a backslash is added to the end of the pattern. This is done to provide a
179 way of testing the error condition that arises if a pattern finishes with a
180 backslash, because
181 <pre>
182 /abc\/
183 </pre>
184 is interpreted as the first line of a pattern that starts with "abc/", causing
185 pcretest to read the next line as a continuation of the regular expression.
186 </P>
187 <br><a name="SEC4" href="#TOC1">PATTERN MODIFIERS</a><br>
188 <P>
189 A pattern may be followed by any number of modifiers, which are mostly single
190 characters. Following Perl usage, these are referred to below as, for example,
191 "the <b>/i</b> modifier", even though the delimiter of the pattern need not
192 always be a slash, and no slash is used when writing modifiers. Whitespace may
193 appear between the final pattern delimiter and the first modifier, and between
194 the modifiers themselves.
195 </P>
196 <P>
197 The <b>/i</b>, <b>/m</b>, <b>/s</b>, and <b>/x</b> modifiers set the PCRE_CASELESS,
198 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
199 <b>pcre_compile()</b> is called. These four modifier letters have the same
200 effect as they do in Perl. For example:
201 <pre>
202 /caseless/i
203 </pre>
204 The following table shows additional modifiers for setting PCRE compile-time
205 options that do not correspond to anything in Perl:
206 <pre>
207 <b>/8</b> PCRE_UTF8
208 <b>/?</b> PCRE_NO_UTF8_CHECK
209 <b>/A</b> PCRE_ANCHORED
210 <b>/C</b> PCRE_AUTO_CALLOUT
211 <b>/E</b> PCRE_DOLLAR_ENDONLY
212 <b>/f</b> PCRE_FIRSTLINE
213 <b>/J</b> PCRE_DUPNAMES
214 <b>/N</b> PCRE_NO_AUTO_CAPTURE
215 <b>/U</b> PCRE_UNGREEDY
216 <b>/W</b> PCRE_UCP
217 <b>/X</b> PCRE_EXTRA
218 <b>/&#60;JS&#62;</b> PCRE_JAVASCRIPT_COMPAT
219 <b>/&#60;cr&#62;</b> PCRE_NEWLINE_CR
220 <b>/&#60;lf&#62;</b> PCRE_NEWLINE_LF
221 <b>/&#60;crlf&#62;</b> PCRE_NEWLINE_CRLF
222 <b>/&#60;anycrlf&#62;</b> PCRE_NEWLINE_ANYCRLF
223 <b>/&#60;any&#62;</b> PCRE_NEWLINE_ANY
224 <b>/&#60;bsr_anycrlf&#62;</b> PCRE_BSR_ANYCRLF
225 <b>/&#60;bsr_unicode&#62;</b> PCRE_BSR_UNICODE
226 </pre>
227 The modifiers that are enclosed in angle brackets are literal strings as shown,
228 including the angle brackets, but the letters can be in either case. This
229 example sets multiline matching with CRLF as the line ending sequence:
230 <pre>
231 /^abc/m&#60;crlf&#62;
232 </pre>
233 As well as turning on the PCRE_UTF8 option, the <b>/8</b> modifier also causes
234 any non-printing characters in output strings to be printed using the
235 \x{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
236 options are given in the
237 <a href="pcreapi.html"><b>pcreapi</b></a>
238 documentation.
239 </P>
240 <br><b>
241 Finding all matches in a string
242 </b><br>
243 <P>
244 Searching for all possible matches within each subject string can be requested
245 by the <b>/g</b> or <b>/G</b> modifier. After finding a match, PCRE is called
246 again to search the remainder of the subject string. The difference between
247 <b>/g</b> and <b>/G</b> is that the former uses the <i>startoffset</i> argument to
248 <b>pcre_exec()</b> to start searching at a new point within the entire string
249 (which is in effect what Perl does), whereas the latter passes over a shortened
250 substring. This makes a difference to the matching process if the pattern
251 begins with a lookbehind assertion (including \b or \B).
252 </P>
253 <P>
254 If any call to <b>pcre_exec()</b> in a <b>/g</b> or <b>/G</b> sequence matches an
255 empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
256 PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
257 same point. If this second match fails, the start offset is advanced, and the
258 normal match is retried. This imitates the way Perl handles such cases when
259 using the <b>/g</b> modifier or the <b>split()</b> function. Normally, the start
260 offset is advanced by one character, but if the newline convention recognizes
261 CRLF as a newline, and the current character is CR followed by LF, an advance
262 of two is used.
263 </P>
264 <br><b>
265 Other modifiers
266 </b><br>
267 <P>
268 There are yet more modifiers for controlling the way <b>pcretest</b>
269 operates.
270 </P>
271 <P>
272 The <b>/+</b> modifier requests that as well as outputting the substring that
273 matched the entire pattern, pcretest should in addition output the remainder of
274 the subject string. This is useful for tests where the subject contains
275 multiple copies of the same substring.
276 </P>
277 <P>
278 The <b>/B</b> modifier is a debugging feature. It requests that <b>pcretest</b>
279 output a representation of the compiled byte code after compilation. Normally
280 this information contains length and offset values; however, if <b>/Z</b> is
281 also present, this data is replaced by spaces. This is a special feature for
282 use in the automatic test scripts; it ensures that the same output is generated
283 for different internal link sizes.
284 </P>
285 <P>
286 The <b>/D</b> modifier is a PCRE debugging feature, and is equivalent to
287 <b>/BI</b>, that is, both the <b>/B</b> and the <b>/I</b> modifiers.
288 </P>
289 <P>
290 The <b>/F</b> modifier causes <b>pcretest</b> to flip the byte order of the
291 fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
292 facility is for testing the feature in PCRE that allows it to execute patterns
293 that were compiled on a host with a different endianness. This feature is not
294 available when the POSIX interface to PCRE is being used, that is, when the
295 <b>/P</b> pattern modifier is specified. See also the section about saving and
296 reloading compiled patterns below.
297 </P>
298 <P>
299 The <b>/I</b> modifier requests that <b>pcretest</b> output information about the
300 compiled pattern (whether it is anchored, has a fixed first character, and
301 so on). It does this by calling <b>pcre_fullinfo()</b> after compiling a
302 pattern. If the pattern is studied, the results of that are also output.
303 </P>
304 <P>
305 The <b>/K</b> modifier requests <b>pcretest</b> to show names from backtracking
306 control verbs that are returned from calls to <b>pcre_exec()</b>. It causes
307 <b>pcretest</b> to create a <b>pcre_extra</b> block if one has not already been
308 created by a call to <b>pcre_study()</b>, and to set the PCRE_EXTRA_MARK flag
309 and the <b>mark</b> field within it, every time that <b>pcre_exec()</b> is
310 called. If the variable that the <b>mark</b> field points to is non-NULL for a
311 match, non-match, or partial match, <b>pcretest</b> prints the string to which
312 it points. For a match, this is shown on a line by itself, tagged with "MK:".
313 For a non-match it is added to the message.
314 </P>
315 <P>
316 The <b>/L</b> modifier must be followed directly by the name of a locale, for
317 example,
318 <pre>
319 /pattern/Lfr_FR
320 </pre>
321 For this reason, it must be the last modifier. The given locale is set,
322 <b>pcre_maketables()</b> is called to build a set of character tables for the
323 locale, and this is then passed to <b>pcre_compile()</b> when compiling the
324 regular expression. Without an <b>/L</b> (or <b>/T</b>) modifier, NULL is passed
325 as the tables pointer; that is, <b>/L</b> applies only to the expression on
326 which it appears.
327 </P>
328 <P>
329 The <b>/M</b> modifier causes the size of memory block used to hold the compiled
330 pattern to be output.
331 </P>
332 <P>
333 The <b>/S</b> modifier causes <b>pcre_study()</b> to be called after the
334 expression has been compiled, and the results used when the expression is
335 matched.
336 </P>
337 <P>
338 The <b>/T</b> modifier must be followed by a single digit. It causes a specific
339 set of built-in character tables to be passed to <b>pcre_compile()</b>. It is
340 used in the standard PCRE tests to check behaviour with different character
341 tables. The digit specifies the tables as follows:
342 <pre>
343 0 the default ASCII tables, as distributed in
344 pcre_chartables.c.dist
345 1 a set of tables defining ISO 8859 characters
346 </pre>
347 In table 1, some characters whose codes are greater than 128 are identified as
348 letters, digits, spaces, etc.
349 </P>
350 <br><b>
351 Using the POSIX wrapper API
352 </b><br>
353 <P>
354 The <b>/P</b> modifier causes <b>pcretest</b> to call PCRE via the POSIX wrapper
355 API rather than its native API. When <b>/P</b> is set, the following modifiers
356 set options for the <b>regcomp()</b> function:
357 <pre>
358 /i REG_ICASE
359 /m REG_NEWLINE
360 /N REG_NOSUB
361 /s REG_DOTALL )
362 /U REG_UNGREEDY ) These options are not part of
363 /W REG_UCP ) the POSIX standard
364 /8 REG_UTF8 )
365 </pre>
366 The <b>/+</b> modifier works as described above. All other modifiers are
367 ignored.
368 </P>
369 <br><a name="SEC5" href="#TOC1">DATA LINES</a><br>
370 <P>
371 Before each data line is passed to <b>pcre_exec()</b>, leading and trailing
372 whitespace is removed, and it is then scanned for \ escapes. Some of these are
373 pretty esoteric features, intended for checking out some of the more
374 complicated features of PCRE. If you are just testing "ordinary" regular
375 expressions, you probably don't need any of these. The following escapes are
376 recognized:
377 <pre>
378 \a alarm (BEL, \x07)
379 \b backspace (\x08)
380 \e escape (\x27)
381 \f formfeed (\x0c)
382 \n newline (\x0a)
383 \qdd set the PCRE_MATCH_LIMIT limit to dd (any number of digits)
384 \r carriage return (\x0d)
385 \t tab (\x09)
386 \v vertical tab (\x0b)
387 \nnn octal character (up to 3 octal digits)
388 always a byte unless &#62; 255 in UTF-8 mode
389 \xhh hexadecimal byte (up to 2 hex digits)
390 \x{hh...} hexadecimal character, any number of digits in UTF-8 mode
391 \A pass the PCRE_ANCHORED option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
392 \B pass the PCRE_NOTBOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
393 \Cdd call pcre_copy_substring() for substring dd after a successful match (number less than 32)
394 \Cname call pcre_copy_named_substring() for substring "name" after a successful match (name termin-
395 ated by next non alphanumeric character)
396 \C+ show the current captured substrings at callout time
397 \C- do not supply a callout function
398 \C!n return 1 instead of 0 when callout number n is reached
399 \C!n!m return 1 instead of 0 when callout number n is reached for the nth time
400 \C*n pass the number n (may be negative) as callout data; this is used as the callout return value
401 \D use the <b>pcre_dfa_exec()</b> match function
402 \F only shortest match for <b>pcre_dfa_exec()</b>
403 \Gdd call pcre_get_substring() for substring dd after a successful match (number less than 32)
404 \Gname call pcre_get_named_substring() for substring "name" after a successful match (name termin-
405 ated by next non-alphanumeric character)
406 \L call pcre_get_substringlist() after a successful match
407 \M discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings
408 \N pass the PCRE_NOTEMPTY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the
409 PCRE_NOTEMPTY_ATSTART option
410 \Odd set the size of the output vector passed to <b>pcre_exec()</b> to dd (any number of digits)
411 \P pass the PCRE_PARTIAL_SOFT option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>; if used twice, pass the
412 PCRE_PARTIAL_HARD option
413 \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd (any number of digits)
414 \R pass the PCRE_DFA_RESTART option to <b>pcre_dfa_exec()</b>
415 \S output details of memory get/free calls during matching
416 \Y pass the PCRE_NO_START_OPTIMIZE option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
417 \Z pass the PCRE_NOTEOL option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
418 \? pass the PCRE_NO_UTF8_CHECK option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
419 \&#62;dd start the match at offset dd (optional "-"; then any number of digits); this sets the <i>startoffset</i>
420 argument for <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
421 \&#60;cr&#62; pass the PCRE_NEWLINE_CR option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
422 \&#60;lf&#62; pass the PCRE_NEWLINE_LF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
423 \&#60;crlf&#62; pass the PCRE_NEWLINE_CRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
424 \&#60;anycrlf&#62; pass the PCRE_NEWLINE_ANYCRLF option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
425 \&#60;any&#62; pass the PCRE_NEWLINE_ANY option to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>
426 </pre>
427 Note that \xhh always specifies one byte, even in UTF-8 mode; this makes it
428 possible to construct invalid UTF-8 sequences for testing purposes. On the
429 other hand, \x{hh} is interpreted as a UTF-8 character in UTF-8 mode,
430 generating more than one byte if the value is greater than 127. When not in
431 UTF-8 mode, it generates one byte for values less than 256, and causes an error
432 for greater values.
433 </P>
434 <P>
435 The escapes that specify line ending sequences are literal strings, exactly as
436 shown. No more than one newline setting should be present in any data line.
437 </P>
438 <P>
439 A backslash followed by anything else just escapes the anything else. If
440 the very last character is a backslash, it is ignored. This gives a way of
441 passing an empty line as data, since a real empty line terminates the data
442 input.
443 </P>
444 <P>
445 If \M is present, <b>pcretest</b> calls <b>pcre_exec()</b> several times, with
446 different values in the <i>match_limit</i> and <i>match_limit_recursion</i>
447 fields of the <b>pcre_extra</b> data structure, until it finds the minimum
448 numbers for each parameter that allow <b>pcre_exec()</b> to complete. The
449 <i>match_limit</i> 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 <i>match_limit_recursion</i> 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 </P>
457 <P>
458 When \O is used, the value specified may be higher or lower than the size set
459 by the <b>-O</b> command line option (or defaulted to 45); \O applies only to
460 the call of <b>pcre_exec()</b> for the line in which it appears.
461 </P>
462 <P>
463 If the <b>/P</b> modifier was present on the pattern, causing the POSIX wrapper
464 API to be used, the only option-setting sequences that have any effect are \B,
465 \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
466 to be passed to <b>regexec()</b>.
467 </P>
468 <P>
469 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use
470 of the <b>/8</b> modifier on the pattern. It is recognized always. There may be
471 any number of hexadecimal digits inside the braces. The result is from one to
472 six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
473 allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
474 valid Unicode code points, or indeed valid UTF-8 characters according to the
475 later rules in RFC 3629.
476 </P>
477 <br><a name="SEC6" href="#TOC1">THE ALTERNATIVE MATCHING FUNCTION</a><br>
478 <P>
479 By default, <b>pcretest</b> uses the standard PCRE matching function,
480 <b>pcre_exec()</b> to match each data line. From release 6.0, PCRE supports an
481 alternative matching function, <b>pcre_dfa_test()</b>, which operates in a
482 different way, and has some restrictions. The differences between the two
483 functions are described in the
484 <a href="pcrematching.html"><b>pcrematching</b></a>
485 documentation.
486 </P>
487 <P>
488 If a data line contains the \D escape sequence, or if the command line
489 contains the <b>-dfa</b> option, the alternative matching function is called.
490 This function finds all possible matches at a given point. If, however, the \F
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 </P>
494 <br><a name="SEC7" href="#TOC1">DEFAULT OUTPUT FROM PCRETEST</a><br>
495 <P>
496 This section describes the output when the normal matching function,
497 <b>pcre_exec()</b>, is being used.
498 </P>
499 <P>
500 When a match succeeds, pcretest outputs the list of captured substrings that
501 <b>pcre_exec()</b> returns, starting with number 0 for the string that matched
502 the whole pattern. Otherwise, it outputs "No match" when the return is
503 PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
504 substring when <b>pcre_exec()</b> returns PCRE_ERROR_PARTIAL. (Note that this is
505 the entire substring that was inspected during the partial match; it may
506 include characters before the actual match start if a lookbehind assertion,
507 \K, \b, or \B was involved.) For any other returns, it outputs the PCRE
508 negative error number. Here is an example of an interactive <b>pcretest</b> run.
509 <pre>
510 $ pcretest
511 PCRE version 7.0 30-Nov-2006
512
513 re&#62; /^abc(\d+)/
514 data&#62; abc123
515 0: abc123
516 1: 123
517 data&#62; xyz
518 No match
519 </pre>
520 Note that unset capturing substrings that are not followed by one that is set
521 are not returned by <b>pcre_exec()</b>, and are not shown by <b>pcretest</b>. In
522 the following example, there are two capturing substrings, but when the first
523 data line is matched, the second, unset substring is not shown. An "internal"
524 unset substring is shown as "&#60;unset&#62;", as for the second data line.
525 <pre>
526 re&#62; /(a)|(b)/
527 data&#62; a
528 0: a
529 1: a
530 data&#62; b
531 0: b
532 1: &#60;unset&#62;
533 2: b
534 </pre>
535 If the strings contain any non-printing characters, they are output as \0x
536 escapes, or as \x{...} escapes if the <b>/8</b> modifier was present on the
537 pattern. See below for the definition of non-printing characters. If the
538 pattern has the <b>/+</b> modifier, the output for substring 0 is followed by
539 the the rest of the subject string, identified by "0+" like this:
540 <pre>
541 re&#62; /cat/+
542 data&#62; cataract
543 0: cat
544 0+ aract
545 </pre>
546 If the pattern has the <b>/g</b> or <b>/G</b> modifier, the results of successive
547 matching attempts are output in sequence, like this:
548 <pre>
549 re&#62; /\Bi(\w\w)/g
550 data&#62; Mississippi
551 0: iss
552 1: ss
553 0: iss
554 1: ss
555 0: ipp
556 1: pp
557 </pre>
558 "No match" is output only if the first match attempt fails.
559 </P>
560 <P>
561 If any of the sequences <b>\C</b>, <b>\G</b>, or <b>\L</b> are present in a
562 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 parentheses after each string for <b>\C</b> and <b>\G</b>.
567 </P>
568 <P>
569 Note that whereas patterns can be continued over several lines (a plain "&#62;"
570 prompt is used for continuations), data lines may not. However newlines can be
571 included in data by means of the \n escape (or \r, \r\n, etc., depending on
572 the newline sequence setting).
573 </P>
574 <br><a name="SEC8" href="#TOC1">OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION</a><br>
575 <P>
576 When the alternative matching function, <b>pcre_dfa_exec()</b>, is used (by
577 means of the \D escape sequence or the <b>-dfa</b> command line option), the
578 output consists of a list of all the matches that start at the first point in
579 the subject where there is at least one match. For example:
580 <pre>
581 re&#62; /(tang|tangerine|tan)/
582 data&#62; yellow tangerine\D
583 0: tangerine
584 1: tang
585 2: tan
586 </pre>
587 (Using the normal matching function on this data finds only "tang".) The
588 longest matching string is always given first (and numbered zero). After a
589 PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
590 partially matching substring. (Note that this is the entire substring that was
591 inspected during the partial match; it may include characters before the actual
592 match start if a lookbehind assertion, \K, \b, or \B was involved.)
593 </P>
594 <P>
595 If <b>/g</b> is present on the pattern, the search for further matches resumes
596 at the end of the longest match. For example:
597 <pre>
598 re&#62; /(tang|tangerine|tan)/g
599 data&#62; yellow tangerine and tangy sultana\D
600 0: tangerine
601 1: tang
602 2: tan
603 0: tang
604 1: tan
605 0: tan
606 </pre>
607 Since the matching function does not support substring capture, the escape
608 sequences that are concerned with captured substrings are not relevant.
609 </P>
610 <br><a name="SEC9" href="#TOC1">RESTARTING AFTER A PARTIAL MATCH</a><br>
611 <P>
612 When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
613 indicating that the subject partially matched the pattern, you can restart the
614 match with additional subject data by means of the \R escape sequence. For
615 example:
616 <pre>
617 re&#62; /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
618 data&#62; 23ja\P\D
619 Partial match: 23ja
620 data&#62; n05\R\D
621 0: n05
622 </pre>
623 For further information about partial matching, see the
624 <a href="pcrepartial.html"><b>pcrepartial</b></a>
625 documentation.
626 </P>
627 <br><a name="SEC10" href="#TOC1">CALLOUTS</a><br>
628 <P>
629 If the pattern contains any callout requests, <b>pcretest</b>'s callout function
630 is called during matching. This works with both matching functions. By default,
631 the called function displays the callout number, the start and current
632 positions in the text at the callout time, and the next pattern item to be
633 tested. For example, the output
634 <pre>
635 ---&#62;pqrabcdef
636 0 ^ ^ \d
637 </pre>
638 indicates that callout number 0 occurred for a match attempt starting at the
639 fourth character of the subject string, when the pointer was at the seventh
640 character of the data, and when the next pattern item was \d. Just one
641 circumflex is output if the start and current positions are the same.
642 </P>
643 <P>
644 Callouts numbered 255 are assumed to be automatic callouts, inserted as a
645 result of the <b>/C</b> pattern modifier. In this case, instead of showing the
646 callout number, the offset in the pattern, preceded by a plus, is output. For
647 example:
648 <pre>
649 re&#62; /\d?[A-E]\*/C
650 data&#62; E*
651 ---&#62;E*
652 +0 ^ \d?
653 +3 ^ [A-E]
654 +8 ^^ \*
655 +10 ^ ^
656 0: E*
657 </pre>
658 The callout function in <b>pcretest</b> returns zero (carry on matching) by
659 default, but you can use a \C item in a data line (as described above) to
660 change this.
661 </P>
662 <P>
663 Inserting callouts can be helpful when using <b>pcretest</b> to check
664 complicated regular expressions. For further information about callouts, see
665 the
666 <a href="pcrecallout.html"><b>pcrecallout</b></a>
667 documentation.
668 </P>
669 <br><a name="SEC11" href="#TOC1">NON-PRINTING CHARACTERS</a><br>
670 <P>
671 When <b>pcretest</b> is outputting text in the compiled version of a pattern,
672 bytes other than 32-126 are always treated as non-printing characters are are
673 therefore shown as hex escapes.
674 </P>
675 <P>
676 When <b>pcretest</b> is outputting text that is a matched part of a subject
677 string, it behaves in the same way, unless a different locale has been set for
678 the pattern (using the <b>/L</b> modifier). In this case, the <b>isprint()</b>
679 function to distinguish printing and non-printing characters.
680 </P>
681 <br><a name="SEC12" href="#TOC1">SAVING AND RELOADING COMPILED PATTERNS</a><br>
682 <P>
683 The facilities described in this section are not available when the POSIX
684 inteface to PCRE is being used, that is, when the <b>/P</b> pattern modifier is
685 specified.
686 </P>
687 <P>
688 When the POSIX interface is not in use, you can cause <b>pcretest</b> to write a
689 compiled pattern to a file, by following the modifiers with &#62; and a file name.
690 For example:
691 <pre>
692 /pattern/im &#62;/some/file
693 </pre>
694 See the
695 <a href="pcreprecompile.html"><b>pcreprecompile</b></a>
696 documentation for a discussion about saving and re-using compiled patterns.
697 </P>
698 <P>
699 The data that is written is binary. The first eight bytes are the length of the
700 compiled pattern data followed by the length of the optional study data, each
701 written as four bytes in big-endian order (most significant byte first). If
702 there is no study data (either the pattern was not studied, or studying did not
703 return any data), the second length is zero. The lengths are followed by an
704 exact copy of the compiled pattern. If there is additional study data, this
705 follows immediately after the compiled pattern. After writing the file,
706 <b>pcretest</b> expects to read a new pattern.
707 </P>
708 <P>
709 A saved pattern can be reloaded into <b>pcretest</b> by specifing &#60; and a file
710 name instead of a pattern. The name of the file must not contain a &#60; character,
711 as otherwise <b>pcretest</b> will interpret the line as a pattern delimited by &#60;
712 characters.
713 For example:
714 <pre>
715 re&#62; &#60;/some/file
716 Compiled regex loaded from /some/file
717 No study data
718 </pre>
719 When the pattern has been loaded, <b>pcretest</b> proceeds to read data lines in
720 the usual way.
721 </P>
722 <P>
723 You can copy a file written by <b>pcretest</b> to a different host and reload it
724 there, even if the new host has opposite endianness to the one on which the
725 pattern was compiled. For example, you can compile on an i86 machine and run on
726 a SPARC machine.
727 </P>
728 <P>
729 File names for saving and reloading can be absolute or relative, but note that
730 the shell facility of expanding a file name that starts with a tilde (~) is not
731 available.
732 </P>
733 <P>
734 The ability to save and reload files in <b>pcretest</b> is intended for testing
735 and experimentation. It is not intended for production use because only a
736 single pattern can be written to a file. Furthermore, there is no facility for
737 supplying custom character tables for use with a reloaded pattern. If the
738 original pattern was compiled with custom tables, an attempt to match a subject
739 string using a reloaded pattern is likely to cause <b>pcretest</b> to crash.
740 Finally, if you attempt to load a file that is not in the correct format, the
741 result is undefined.
742 </P>
743 <br><a name="SEC13" href="#TOC1">SEE ALSO</a><br>
744 <P>
745 <b>pcre</b>(3), <b>pcreapi</b>(3), <b>pcrecallout</b>(3), <b>pcrematching</b>(3),
746 <b>pcrepartial</b>(d), <b>pcrepattern</b>(3), <b>pcreprecompile</b>(3).
747 </P>
748 <br><a name="SEC14" href="#TOC1">AUTHOR</a><br>
749 <P>
750 Philip Hazel
751 <br>
752 University Computing Service
753 <br>
754 Cambridge CB2 3QH, England.
755 <br>
756 </P>
757 <br><a name="SEC15" href="#TOC1">REVISION</a><br>
758 <P>
759 Last updated: 07 November 2010
760 <br>
761 Copyright &copy; 1997-2010 University of Cambridge.
762 <br>
763 <p>
764 Return to the <a href="index.html">PCRE index page</a>.
765 </p>

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