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

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