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1 nigel 73 PCRETEST(1) PCRETEST(1)
2 nigel 41
4 nigel 73
5     NAME
6     pcretest - a program for testing Perl-compatible regular expressions.
8 nigel 53 SYNOPSIS
9 nigel 41
10 nigel 75 pcretest [-C] [-d] [-i] [-m] [-o osize] [-p] [-t] [source]
11     [destination]
13 nigel 73 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 nigel 75 documentation. For details of the PCRE library function calls and their
18     options, see the pcreapi documentation.
19 nigel 41
21 nigel 63 OPTIONS
22 nigel 41
23 nigel 73 -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.
26 nigel 63
27 nigel 75 -d Behave as if each regex had the /D (debug) modifier; the
28 nigel 73 internal form is output after compilation.
29 nigel 41
30 nigel 73 -i Behave as if each regex had the /I modifier; information
31     about the compiled pattern is given after compilation.
32 nigel 41
33 nigel 73 -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.
37 nigel 41
38 nigel 73 -o osize Set the number of elements in the output vector that is used
39 nigel 75 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).
43 nigel 41
44 nigel 73 -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.
47 nigel 41
48 nigel 73 -t Run each compile, study, and match many times with a timer,
49     and output resulting time per compile or match (in millisec-
50 nigel 75 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.
53 nigel 49
55 nigel 63 DESCRIPTION
56 nigel 41
57 nigel 75 If pcretest is given two filename arguments, it reads from the first
58 nigel 73 and writes to the second. If it is given only one filename argument, it
59 nigel 75 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 nigel 73 "re>" to prompt for regular expressions, and "data>" to prompt for data
62     lines.
63 nigel 41
64 nigel 73 The program handles any number of sets of input on a single input file.
65 nigel 75 Each set starts with a regular expression, and continues with any num-
66 nigel 73 ber of data lines to be matched against the pattern.
67 nigel 41
68 nigel 75 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.
72 nigel 63
73 nigel 75 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
76 nigel 63
77 nigel 73 /(a|bc)x+yz/
78 nigel 41
79 nigel 75 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 nigel 73 delimiter within the pattern by escaping it, for example
83 nigel 41
84 nigel 73 /abc\/def/
85 nigel 41
86 nigel 75 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 nigel 73 lowed by a backslash, for example,
90 nigel 41
91 nigel 73 /abc/\
92 nigel 41
93 nigel 75 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 nigel 73 finishes with a backslash, because
96 nigel 49
97 nigel 73 /abc\/
98 nigel 49
99 nigel 75 is interpreted as the first line of a pattern that starts with "abc/",
100 nigel 73 causing pcretest to read the next line as a continuation of the regular
101     expression.
102 nigel 49
103 nigel 41
105 nigel 41
106 nigel 75 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.
112 nigel 41
113 nigel 75 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 nigel 73 /caseless/i
119 nigel 41
120 nigel 75 The following table shows additional modifiers for setting PCRE options
121     that do not correspond to anything in Perl:
122 nigel 41
123 nigel 75 /A PCRE_ANCHORED
128     /X PCRE_EXTRA
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 nigel 73 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 nigel 75 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 nigel 73 process if the pattern begins with a lookbehind assertion (including \b
138     or \B).
139 nigel 49
140 nigel 75 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 nigel 73 dles such cases when using the /g modifier or the split() function.
146 nigel 49
147 nigel 75 There are yet more modifiers for controlling the way pcretest operates.
148 nigel 49
149 nigel 75 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 nigel 73 subject contains multiple copies of the same substring.
153 nigel 41
154 nigel 75 The /L modifier must be followed directly by the name of a locale, for
155 nigel 73 example,
156 nigel 41
157 nigel 75 /pattern/Lfr_FR
158 nigel 41
159 nigel 75 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.
165 nigel 41
166 nigel 75 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.
171 nigel 63
172 nigel 73 The /D modifier is a PCRE debugging feature, which also assumes /I. It
173 nigel 75 causes the internal form of compiled regular expressions to be output
174 nigel 73 after compilation. If the pattern was studied, the information returned
175     is also output.
176 nigel 41
177 nigel 75 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 nigel 73 has been compiled, and the results used when the expression is matched.
187 nigel 41
188 nigel 75 The /M modifier causes the size of memory block used to hold the com-
189 nigel 73 piled pattern to be output.
190 nigel 41
191 nigel 75 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.
196 nigel 41
197 nigel 75 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 nigel 73 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.
202 nigel 41
203 nigel 75 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 nigel 73 checking of the string for UTF-8 validity.
206 nigel 41
207 nigel 71
208 nigel 53 DATA LINES
209 nigel 63
210 nigel 75 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 nigel 73 following escapes are recognized:
216 nigel 49
217 nigel 73 \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 nigel 75 after a successful match (number less than 32)
233 nigel 73 \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 nigel 75 data; this is used as the callout return value
245 nigel 73 \Gdd call pcre_get_substring() for substring dd
246 nigel 75 after a successful match (number less than 32)
247 nigel 73 \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 nigel 75 pcre_exec() to dd (any number of digits)
256     \P pass the PCRE_PARTIAL option to pcre_exec()
257 nigel 73 \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 nigel 75 \>dd start the match at offset dd (any number of digits);
262     this sets the startoffset argument for pcre_exec()
263 nigel 71
264 nigel 75 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 nigel 73 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.
277 nigel 41
278 nigel 75 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.
281 nigel 63
282 nigel 75 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.
285 nigel 41
286 nigel 75 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.
290 nigel 41
291 nigel 53
293 nigel 53
294 nigel 73 When a match succeeds, pcretest outputs the list of captured substrings
295 nigel 75 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.
300 nigel 53
301 nigel 73 $ pcretest
302 nigel 75 PCRE version 5.00 07-Sep-2004
303 nigel 53
304 nigel 73 re> /^abc(\d+)/
305     data> abc123
306     0: abc123
307     1: 123
308     data> xyz
309     No match
310 nigel 53
311 nigel 75 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:
316 nigel 53
317 nigel 73 re> /cat/+
318     data> cataract
319     0: cat
320     0+ aract
321 nigel 53
322 nigel 75 If the pattern has the /g or /G modifier, the results of successive
323 nigel 73 matching attempts are output in sequence, like this:
324 nigel 53
325 nigel 73 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
333 nigel 53
334 nigel 73 "No match" is output only if the first match attempt fails.
335 nigel 53
336 nigel 75 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 nigel 73 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 nigel 75 (that is, the return from the extraction function) is given in paren-
341 nigel 73 theses after each string for \C and \G.
342 nigel 53
343 nigel 75 Note that while patterns can be continued over several lines (a plain
344 nigel 73 ">" prompt is used for continuations), data lines may not. However new-
345     lines can be included in data by means of the \n escape.
346 nigel 53
348 nigel 75 CALLOUTS
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.
443 nigel 63 AUTHOR
444 nigel 53
445 nigel 73 Philip Hazel <ph10@cam.ac.uk>
446     University Computing Service,
447     Cambridge CB2 3QG, England.
448 nigel 53
449 nigel 75 Last updated: 10 September 2004
450     Copyright (c) 1997-2004 University of Cambridge.

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