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1 | This file contains the PCRE man page that described the pcretest program. Note |
2 | that not all of the features of PCRE are available in the limited version that | |
3 | is built with Exim. | |
4 | ------------------------------------------------------------------------------- | |
5 | ||
6 | PCRETEST(1) PCRETEST(1) | |
7 | ||
8 | ||
9 | ||
10 | NAME | |
11 | pcretest - a program for testing Perl-compatible regular expressions. | |
12 | ||
13 | SYNOPSIS | |
14 | ||
15 | pcretest [-C] [-d] [-i] [-m] [-o osize] [-p] [-t] [source] | |
16 | [destination] | |
17 | ||
18 | pcretest was written as a test program for the PCRE regular expression | |
19 | library itself, but it can also be used for experimenting with regular | |
20 | expressions. This document describes the features of the test program; | |
21 | for details of the regular expressions themselves, see the pcrepattern | |
22 | documentation. For details of the PCRE library function calls and their | |
23 | options, see the pcreapi documentation. | |
24 | ||
25 | ||
26 | OPTIONS | |
27 | ||
28 | -C Output the version number of the PCRE library, and all avail- | |
29 | able information about the optional features that are | |
30 | included, and then exit. | |
31 | ||
32 | -d Behave as if each regex had the /D (debug) modifier; the | |
33 | internal form is output after compilation. | |
34 | ||
35 | -i Behave as if each regex had the /I modifier; information | |
36 | about the compiled pattern is given after compilation. | |
37 | ||
38 | -m Output the size of each compiled pattern after it has been | |
39 | compiled. This is equivalent to adding /M to each regular | |
40 | expression. For compatibility with earlier versions of | |
41 | pcretest, -s is a synonym for -m. | |
42 | ||
43 | -o osize Set the number of elements in the output vector that is used | |
44 | when calling pcre_exec() to be osize. The default value is | |
45 | 45, which is enough for 14 capturing subexpressions. The vec- | |
46 | tor size can be changed for individual matching calls by | |
47 | including \O in the data line (see below). | |
48 | ||
49 | -p Behave as if each regex has /P modifier; the POSIX wrapper | |
50 | API is used to call PCRE. None of the other options has any | |
51 | effect when -p is set. | |
52 | ||
53 | -t Run each compile, study, and match many times with a timer, | |
54 | and output resulting time per compile or match (in millisec- | |
55 | onds). Do not set -m with -t, because you will then get the | |
56 | size output a zillion times, and the timing will be dis- | |
57 | torted. | |
58 | ||
59 | ||
60 | DESCRIPTION | |
61 | ||
62 | If pcretest is given two filename arguments, it reads from the first | |
63 | and writes to the second. If it is given only one filename argument, it | |
64 | reads from that file and writes to stdout. Otherwise, it reads from | |
65 | stdin and writes to stdout, and prompts for each line of input, using | |
66 | "re>" to prompt for regular expressions, and "data>" to prompt for data | |
67 | lines. | |
68 | ||
69 | The program handles any number of sets of input on a single input file. | |
70 | Each set starts with a regular expression, and continues with any num- | |
71 | ber of data lines to be matched against the pattern. | |
72 | ||
73 | Each data line is matched separately and independently. If you want to | |
74 | do multiple-line matches, you have to use the \n escape sequence in a | |
75 | single line of input to encode the newline characters. The maximum | |
76 | length of data line is 30,000 characters. | |
77 | ||
78 | An empty line signals the end of the data lines, at which point a new | |
79 | regular expression is read. The regular expressions are given enclosed | |
80 | in any non-alphanumeric delimiters other than backslash, for example | |
81 | ||
82 | /(a|bc)x+yz/ | |
83 | ||
84 | White space before the initial delimiter is ignored. A regular expres- | |
85 | sion may be continued over several input lines, in which case the new- | |
86 | line characters are included within it. It is possible to include the | |
87 | delimiter within the pattern by escaping it, for example | |
88 | ||
89 | /abc\/def/ | |
90 | ||
91 | If you do so, the escape and the delimiter form part of the pattern, | |
92 | but since delimiters are always non-alphanumeric, this does not affect | |
93 | its interpretation. If the terminating delimiter is immediately fol- | |
94 | lowed by a backslash, for example, | |
95 | ||
96 | /abc/\ | |
97 | ||
98 | then a backslash is added to the end of the pattern. This is done to | |
99 | provide a way of testing the error condition that arises if a pattern | |
100 | finishes with a backslash, because | |
101 | ||
102 | /abc\/ | |
103 | ||
104 | is interpreted as the first line of a pattern that starts with "abc/", | |
105 | causing pcretest to read the next line as a continuation of the regular | |
106 | expression. | |
107 | ||
108 | ||
109 | PATTERN MODIFIERS | |
110 | ||
111 | A pattern may be followed by any number of modifiers, which are mostly | |
112 | single characters. Following Perl usage, these are referred to below | |
113 | as, for example, "the /i modifier", even though the delimiter of the | |
114 | pattern need not always be a slash, and no slash is used when writing | |
115 | modifiers. Whitespace may appear between the final pattern delimiter | |
116 | and the first modifier, and between the modifiers themselves. | |
117 | ||
118 | The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE, | |
119 | PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com- | |
120 | pile() is called. These four modifier letters have the same effect as | |
121 | they do in Perl. For example: | |
122 | ||
123 | /caseless/i | |
124 | ||
125 | The following table shows additional modifiers for setting PCRE options | |
126 | that do not correspond to anything in Perl: | |
127 | ||
128 | /A PCRE_ANCHORED | |
129 | /C PCRE_AUTO_CALLOUT | |
130 | /E PCRE_DOLLAR_ENDONLY | |
131 | /N PCRE_NO_AUTO_CAPTURE | |
132 | /U PCRE_UNGREEDY | |
133 | /X PCRE_EXTRA | |
134 | ||
135 | Searching for all possible matches within each subject string can be | |
136 | requested by the /g or /G modifier. After finding a match, PCRE is | |
137 | called again to search the remainder of the subject string. The differ- | |
138 | ence between /g and /G is that the former uses the startoffset argument | |
139 | to pcre_exec() to start searching at a new point within the entire | |
140 | string (which is in effect what Perl does), whereas the latter passes | |
141 | over a shortened substring. This makes a difference to the matching | |
142 | process if the pattern begins with a lookbehind assertion (including \b | |
143 | or \B). | |
144 | ||
145 | If any call to pcre_exec() in a /g or /G sequence matches an empty | |
146 | string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED | |
147 | flags set in order to search for another, non-empty, match at the same | |
148 | point. If this second match fails, the start offset is advanced by | |
149 | one, and the normal match is retried. This imitates the way Perl han- | |
150 | dles such cases when using the /g modifier or the split() function. | |
151 | ||
152 | There are yet more modifiers for controlling the way pcretest operates. | |
153 | ||
154 | The /+ modifier requests that as well as outputting the substring that | |
155 | matched the entire pattern, pcretest should in addition output the | |
156 | remainder of the subject string. This is useful for tests where the | |
157 | subject contains multiple copies of the same substring. | |
158 | ||
159 | The /L modifier must be followed directly by the name of a locale, for | |
160 | example, | |
161 | ||
162 | /pattern/Lfr_FR | |
163 | ||
164 | For this reason, it must be the last modifier. The given locale is set, | |
165 | pcre_maketables() is called to build a set of character tables for the | |
166 | locale, and this is then passed to pcre_compile() when compiling the | |
167 | regular expression. Without an /L modifier, NULL is passed as the | |
168 | tables pointer; that is, /L applies only to the expression on which it | |
169 | appears. | |
170 | ||
171 | The /I modifier requests that pcretest output information about the | |
172 | compiled pattern (whether it is anchored, has a fixed first character, | |
173 | and so on). It does this by calling pcre_fullinfo() after compiling a | |
174 | pattern. If the pattern is studied, the results of that are also out- | |
175 | put. | |
176 | ||
177 | The /D modifier is a PCRE debugging feature, which also assumes /I. It | |
178 | causes the internal form of compiled regular expressions to be output | |
179 | after compilation. If the pattern was studied, the information returned | |
180 | is also output. | |
181 | ||
182 | The /F modifier causes pcretest to flip the byte order of the fields in | |
183 | the compiled pattern that contain 2-byte and 4-byte numbers. This | |
184 | facility is for testing the feature in PCRE that allows it to execute | |
185 | patterns that were compiled on a host with a different endianness. This | |
186 | feature is not available when the POSIX interface to PCRE is being | |
187 | used, that is, when the /P pattern modifier is specified. See also the | |
188 | section about saving and reloading compiled patterns below. | |
189 | ||
190 | The /S modifier causes pcre_study() to be called after the expression | |
191 | has been compiled, and the results used when the expression is matched. | |
192 | ||
193 | The /M modifier causes the size of memory block used to hold the com- | |
194 | piled pattern to be output. | |
195 | ||
196 | The /P modifier causes pcretest to call PCRE via the POSIX wrapper API | |
197 | rather than its native API. When this is done, all other modifiers | |
198 | except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present, | |
199 | and REG_NEWLINE is set if /m is present. The wrapper functions force | |
200 | PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set. | |
201 | ||
202 | The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option | |
203 | set. This turns on support for UTF-8 character handling in PCRE, pro- | |
204 | vided that it was compiled with this support enabled. This modifier | |
205 | also causes any non-printing characters in output strings to be printed | |
206 | using the \x{hh...} notation if they are valid UTF-8 sequences. | |
207 | ||
208 | If the /? modifier is used with /8, it causes pcretest to call | |
209 | pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the | |
210 | checking of the string for UTF-8 validity. | |
211 | ||
212 | ||
213 | DATA LINES | |
214 | ||
215 | Before each data line is passed to pcre_exec(), leading and trailing | |
216 | whitespace is removed, and it is then scanned for \ escapes. Some of | |
217 | these are pretty esoteric features, intended for checking out some of | |
218 | the more complicated features of PCRE. If you are just testing "ordi- | |
219 | nary" regular expressions, you probably don't need any of these. The | |
220 | following escapes are recognized: | |
221 | ||
222 | \a alarm (= BEL) | |
223 | \b backspace | |
224 | \e escape | |
225 | \f formfeed | |
226 | \n newline | |
227 | \r carriage return | |
228 | \t tab | |
229 | \v vertical tab | |
230 | \nnn octal character (up to 3 octal digits) | |
231 | \xhh hexadecimal character (up to 2 hex digits) | |
232 | \x{hh...} hexadecimal character, any number of digits | |
233 | in UTF-8 mode | |
234 | \A pass the PCRE_ANCHORED option to pcre_exec() | |
235 | \B pass the PCRE_NOTBOL option to pcre_exec() | |
236 | \Cdd call pcre_copy_substring() for substring dd | |
237 | after a successful match (number 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; this is used as the callout return value | |
250 | \Gdd call pcre_get_substring() for substring dd | |
251 | after a successful match (number less than 32) | |
252 | \Gname call pcre_get_named_substring() for substring | |
253 | "name" after a successful match (name termin- | |
254 | ated by next non-alphanumeric character) | |
255 | \L call pcre_get_substringlist() after a | |
256 | successful match | |
257 | \M discover the minimum MATCH_LIMIT setting | |
258 | \N pass the PCRE_NOTEMPTY option to pcre_exec() | |
259 | \Odd set the size of the output vector passed to | |
260 | pcre_exec() to dd (any number of digits) | |
261 | \P pass the PCRE_PARTIAL option to pcre_exec() | |
262 | \S output details of memory get/free calls during matching | |
263 | \Z pass the PCRE_NOTEOL option to pcre_exec() | |
264 | \? pass the PCRE_NO_UTF8_CHECK option to | |
265 | pcre_exec() | |
266 | \>dd start the match at offset dd (any number of digits); | |
267 | this sets the startoffset argument for pcre_exec() | |
268 | ||
269 | A backslash followed by anything else just escapes the anything else. | |
270 | If the very last character is a backslash, it is ignored. This gives a | |
271 | way of passing an empty line as data, since a real empty line termi- | |
272 | nates the data input. | |
273 | ||
274 | If \M is present, pcretest calls pcre_exec() several times, with dif- | |
275 | ferent values in the match_limit field of the pcre_extra data struc- | |
276 | ture, until it finds the minimum number that is needed for pcre_exec() | |
277 | to complete. This number is a measure of the amount of recursion and | |
278 | backtracking that takes place, and checking it out can be instructive. | |
279 | For most simple matches, the number is quite small, but for patterns | |
280 | with very large numbers of matching possibilities, it can become large | |
281 | very quickly with increasing length of subject string. | |
282 | ||
283 | When \O is used, the value specified may be higher or lower than the | |
284 | size set by the -O command line option (or defaulted to 45); \O applies | |
285 | only to the call of pcre_exec() for the line in which it appears. | |
286 | ||
287 | If the /P modifier was present on the pattern, causing the POSIX wrap- | |
288 | per API to be used, only \B and \Z have any effect, causing REG_NOTBOL | |
289 | and REG_NOTEOL to be passed to regexec() respectively. | |
290 | ||
291 | The use of \x{hh...} to represent UTF-8 characters is not dependent on | |
292 | the use of the /8 modifier on the pattern. It is recognized always. | |
293 | There may be any number of hexadecimal digits inside the braces. The | |
294 | result is from one to six bytes, encoded according to the UTF-8 rules. | |
295 | ||
296 | ||
297 | OUTPUT FROM PCRETEST | |
298 | ||
299 | When a match succeeds, pcretest outputs the list of captured substrings | |
300 | that pcre_exec() returns, starting with number 0 for the string that | |
301 | matched the whole pattern. Otherwise, it outputs "No match" or "Partial | |
302 | match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR- | |
303 | TIAL, respectively, and otherwise the PCRE negative error number. Here | |
304 | is an example of an interactive pcretest run. | |
305 | ||
306 | $ pcretest | |
307 | PCRE version 5.00 07-Sep-2004 | |
308 | ||
309 | re> /^abc(\d+)/ | |
310 | data> abc123 | |
311 | 0: abc123 | |
312 | 1: 123 | |
313 | data> xyz | |
314 | No match | |
315 | ||
316 | If the strings contain any non-printing characters, they are output as | |
317 | \0x escapes, or as \x{...} escapes if the /8 modifier was present on | |
318 | the pattern. If the pattern has the /+ modifier, the output for sub- | |
319 | string 0 is followed by the the rest of the subject string, identified | |
320 | by "0+" like this: | |
321 | ||
322 | re> /cat/+ | |
323 | data> cataract | |
324 | 0: cat | |
325 | 0+ aract | |
326 | ||
327 | If the pattern has the /g or /G modifier, the results of successive | |
328 | matching attempts are output in sequence, like this: | |
329 | ||
330 | re> /\Bi(\w\w)/g | |
331 | data> Mississippi | |
332 | 0: iss | |
333 | 1: ss | |
334 | 0: iss | |
335 | 1: ss | |
336 | 0: ipp | |
337 | 1: pp | |
338 | ||
339 | "No match" is output only if the first match attempt fails. | |
340 | ||
341 | If any of the sequences \C, \G, or \L are present in a data line that | |
342 | is successfully matched, the substrings extracted by the convenience | |
343 | functions are output with C, G, or L after the string number instead of | |
344 | a colon. This is in addition to the normal full list. The string length | |
345 | (that is, the return from the extraction function) is given in paren- | |
346 | theses after each string for \C and \G. | |
347 | ||
348 | Note that while patterns can be continued over several lines (a plain | |
349 | ">" prompt is used for continuations), data lines may not. However new- | |
350 | lines can be included in data by means of the \n escape. | |
351 | ||
352 | ||
353 | CALLOUTS | |
354 | ||
355 | If the pattern contains any callout requests, pcretest's callout func- | |
356 | tion is called during matching. By default, it displays the callout | |
357 | number, the start and current positions in the text at the callout | |
358 | time, and the next pattern item to be tested. For example, the output | |
359 | ||
360 | --->pqrabcdef | |
361 | 0 ^ ^ \d | |
362 | ||
363 | indicates that callout number 0 occurred for a match attempt starting | |
364 | at the fourth character of the subject string, when the pointer was at | |
365 | the seventh character of the data, and when the next pattern item was | |
366 | \d. Just one circumflex is output if the start and current positions | |
367 | are the same. | |
368 | ||
369 | Callouts numbered 255 are assumed to be automatic callouts, inserted as | |
370 | a result of the /C pattern modifier. In this case, instead of showing | |
371 | the callout number, the offset in the pattern, preceded by a plus, is | |
372 | output. For example: | |
373 | ||
374 | re> /\d?[A-E]\*/C | |
375 | data> E* | |
376 | --->E* | |
377 | +0 ^ \d? | |
378 | +3 ^ [A-E] | |
379 | +8 ^^ \* | |
380 | +10 ^ ^ | |
381 | 0: E* | |
382 | ||
383 | The callout function in pcretest returns zero (carry on matching) by | |
384 | default, but you can use an \C item in a data line (as described above) | |
385 | to change this. | |
386 | ||
387 | Inserting callouts can be helpful when using pcretest to check compli- | |
388 | cated regular expressions. For further information about callouts, see | |
389 | the pcrecallout documentation. | |
390 | ||
391 | ||
392 | SAVING AND RELOADING COMPILED PATTERNS | |
393 | ||
394 | The facilities described in this section are not available when the | |
395 | POSIX inteface to PCRE is being used, that is, when the /P pattern mod- | |
396 | ifier is specified. | |
397 | ||
398 | When the POSIX interface is not in use, you can cause pcretest to write | |
399 | a compiled pattern to a file, by following the modifiers with > and a | |
400 | file name. For example: | |
401 | ||
402 | /pattern/im >/some/file | |
403 | ||
404 | See the pcreprecompile documentation for a discussion about saving and | |
405 | re-using compiled patterns. | |
406 | ||
407 | The data that is written is binary. The first eight bytes are the | |
408 | length of the compiled pattern data followed by the length of the | |
409 | optional study data, each written as four bytes in big-endian order | |
410 | (most significant byte first). If there is no study data (either the | |
411 | pattern was not studied, or studying did not return any data), the sec- | |
412 | ond length is zero. The lengths are followed by an exact copy of the | |
413 | compiled pattern. If there is additional study data, this follows imme- | |
414 | diately after the compiled pattern. After writing the file, pcretest | |
415 | expects to read a new pattern. | |
416 | ||
417 | A saved pattern can be reloaded into pcretest by specifing < and a file | |
418 | name instead of a pattern. The name of the file must not contain a < | |
419 | character, as otherwise pcretest will interpret the line as a pattern | |
420 | delimited by < characters. For example: | |
421 | ||
422 | re> </some/file | |
423 | Compiled regex loaded from /some/file | |
424 | No study data | |
425 | ||
426 | When the pattern has been loaded, pcretest proceeds to read data lines | |
427 | in the usual way. | |
428 | ||
429 | You can copy a file written by pcretest to a different host and reload | |
430 | it there, even if the new host has opposite endianness to the one on | |
431 | which the pattern was compiled. For example, you can compile on an i86 | |
432 | machine and run on a SPARC machine. | |
433 | ||
434 | File names for saving and reloading can be absolute or relative, but | |
435 | note that the shell facility of expanding a file name that starts with | |
436 | a tilde (~) is not available. | |
437 | ||
438 | The ability to save and reload files in pcretest is intended for test- | |
439 | ing and experimentation. It is not intended for production use because | |
440 | only a single pattern can be written to a file. Furthermore, there is | |
441 | no facility for supplying custom character tables for use with a | |
442 | reloaded pattern. If the original pattern was compiled with custom | |
443 | tables, an attempt to match a subject string using a reloaded pattern | |
444 | is likely to cause pcretest to crash. Finally, if you attempt to load | |
445 | a file that is not in the correct format, the result is undefined. | |
446 | ||
447 | ||
448 | AUTHOR | |
449 | ||
450 | Philip Hazel <ph10@cam.ac.uk> | |
451 | University Computing Service, | |
452 | Cambridge CB2 3QG, England. | |
453 | ||
454 | Last updated: 10 September 2004 | |
455 | Copyright (c) 1997-2004 University of Cambridge. |