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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 | |
495ae4b0 PH |
3 | is built with Exim. |
4 | ------------------------------------------------------------------------------- | |
5 | ||
6 | PCRETEST(1) PCRETEST(1) | |
7 | ||
8 | ||
495ae4b0 PH |
9 | NAME |
10 | pcretest - a program for testing Perl-compatible regular expressions. | |
11 | ||
92e772ff | 12 | |
495ae4b0 PH |
13 | SYNOPSIS |
14 | ||
aa41d2de | 15 | pcretest [options] [source] [destination] |
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16 | |
17 | pcretest was written as a test program for the PCRE regular expression | |
18 | library itself, but it can also be used for experimenting with regular | |
19 | expressions. This document describes the features of the test program; | |
20 | for details of the regular expressions themselves, see the pcrepattern | |
21 | documentation. For details of the PCRE library function calls and their | |
22 | options, see the pcreapi documentation. | |
23 | ||
24 | ||
25 | OPTIONS | |
26 | ||
6bf342e1 PH |
27 | -b Behave as if each regex has the /B (show bytecode) modifier; |
28 | the internal form is output after compilation. | |
29 | ||
495ae4b0 | 30 | -C Output the version number of the PCRE library, and all avail- |
6bf342e1 | 31 | able information about the optional features that are |
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32 | included, and then exit. |
33 | ||
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34 | -d Behave as if each regex has the /D (debug) modifier; the |
35 | internal form and information about the compiled pattern is | |
36 | output after compilation; -d is equivalent to -b -i. | |
495ae4b0 | 37 | |
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38 | -dfa Behave as if each data line contains the \D escape sequence; |
39 | this causes the alternative matching function, | |
40 | pcre_dfa_exec(), to be used instead of the standard | |
41 | pcre_exec() function (more detail is given below). | |
42 | ||
6bf342e1 PH |
43 | -help Output a brief summary these options and then exit. |
44 | ||
8ac170f3 | 45 | -i Behave as if each regex has the /I modifier; information |
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46 | about the compiled pattern is given after compilation. |
47 | ||
8ac170f3 PH |
48 | -m Output the size of each compiled pattern after it has been |
49 | compiled. This is equivalent to adding /M to each regular | |
50 | expression. For compatibility with earlier versions of | |
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51 | pcretest, -s is a synonym for -m. |
52 | ||
8ac170f3 | 53 | -o osize Set the number of elements in the output vector that is used |
6bf342e1 PH |
54 | when calling pcre_exec() or pcre_dfa_exec() to be osize. The |
55 | default value is 45, which is enough for 14 capturing subex- | |
56 | pressions for pcre_exec() or 22 different matches for | |
57 | pcre_dfa_exec(). The vector size can be changed for individ- | |
58 | ual matching calls by including \O in the data line (see | |
59 | below). | |
495ae4b0 | 60 | |
8ac170f3 PH |
61 | -p Behave as if each regex has the /P modifier; the POSIX wrap- |
62 | per API is used to call PCRE. None of the other options has | |
63 | any effect when -p is set. | |
495ae4b0 | 64 | |
aa41d2de PH |
65 | -q Do not output the version number of pcretest at the start of |
66 | execution. | |
67 | ||
68 | -S size On Unix-like systems, set the size of the runtime stack to | |
69 | size megabytes. | |
70 | ||
8ac170f3 PH |
71 | -t Run each compile, study, and match many times with a timer, |
72 | and output resulting time per compile or match (in millisec- | |
73 | onds). Do not set -m with -t, because you will then get the | |
74 | size output a zillion times, and the timing will be dis- | |
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75 | torted. You can control the number of iterations that are |
76 | used for timing by following -t with a number (as a separate | |
77 | item on the command line). For example, "-t 1000" would iter- | |
78 | ate 1000 times. The default is to iterate 500000 times. | |
79 | ||
80 | -tm This is like -t except that it times only the matching phase, | |
81 | not the compile or study phases. | |
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82 | |
83 | ||
84 | DESCRIPTION | |
85 | ||
8ac170f3 | 86 | If pcretest is given two filename arguments, it reads from the first |
495ae4b0 | 87 | and writes to the second. If it is given only one filename argument, it |
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88 | reads from that file and writes to stdout. Otherwise, it reads from |
89 | stdin and writes to stdout, and prompts for each line of input, using | |
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90 | "re>" to prompt for regular expressions, and "data>" to prompt for data |
91 | lines. | |
92 | ||
93 | The program handles any number of sets of input on a single input file. | |
8ac170f3 | 94 | Each set starts with a regular expression, and continues with any num- |
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95 | ber of data lines to be matched against the pattern. |
96 | ||
8ac170f3 | 97 | Each data line is matched separately and independently. If you want to |
aa41d2de | 98 | do multi-line matches, you have to use the \n escape sequence (or \r or |
6bf342e1 PH |
99 | \r\n, etc., depending on the newline setting) in a single line of input |
100 | to encode the newline sequences. There is no limit on the length of | |
101 | data lines; the input buffer is automatically extended if it is too | |
102 | small. | |
495ae4b0 | 103 | |
6bf342e1 PH |
104 | An empty line signals the end of the data lines, at which point a new |
105 | regular expression is read. The regular expressions are given enclosed | |
aa41d2de | 106 | in any non-alphanumeric delimiters other than backslash, for example: |
495ae4b0 PH |
107 | |
108 | /(a|bc)x+yz/ | |
109 | ||
6bf342e1 PH |
110 | White space before the initial delimiter is ignored. A regular expres- |
111 | sion may be continued over several input lines, in which case the new- | |
112 | line characters are included within it. It is possible to include the | |
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113 | delimiter within the pattern by escaping it, for example |
114 | ||
115 | /abc\/def/ | |
116 | ||
6bf342e1 PH |
117 | If you do so, the escape and the delimiter form part of the pattern, |
118 | but since delimiters are always non-alphanumeric, this does not affect | |
119 | its interpretation. If the terminating delimiter is immediately fol- | |
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120 | lowed by a backslash, for example, |
121 | ||
122 | /abc/\ | |
123 | ||
6bf342e1 PH |
124 | then a backslash is added to the end of the pattern. This is done to |
125 | provide a way of testing the error condition that arises if a pattern | |
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126 | finishes with a backslash, because |
127 | ||
128 | /abc\/ | |
129 | ||
6bf342e1 | 130 | is interpreted as the first line of a pattern that starts with "abc/", |
495ae4b0 PH |
131 | causing pcretest to read the next line as a continuation of the regular |
132 | expression. | |
133 | ||
134 | ||
135 | PATTERN MODIFIERS | |
136 | ||
6bf342e1 PH |
137 | A pattern may be followed by any number of modifiers, which are mostly |
138 | single characters. Following Perl usage, these are referred to below | |
139 | as, for example, "the /i modifier", even though the delimiter of the | |
140 | pattern need not always be a slash, and no slash is used when writing | |
141 | modifiers. Whitespace may appear between the final pattern delimiter | |
495ae4b0 PH |
142 | and the first modifier, and between the modifiers themselves. |
143 | ||
144 | The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE, | |
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145 | PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com- |
146 | pile() is called. These four modifier letters have the same effect as | |
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147 | they do in Perl. For example: |
148 | ||
149 | /caseless/i | |
150 | ||
151 | The following table shows additional modifiers for setting PCRE options | |
152 | that do not correspond to anything in Perl: | |
153 | ||
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154 | /A PCRE_ANCHORED |
155 | /C PCRE_AUTO_CALLOUT | |
156 | /E PCRE_DOLLAR_ENDONLY | |
157 | /f PCRE_FIRSTLINE | |
158 | /J PCRE_DUPNAMES | |
159 | /N PCRE_NO_AUTO_CAPTURE | |
160 | /U PCRE_UNGREEDY | |
161 | /X PCRE_EXTRA | |
162 | /<cr> PCRE_NEWLINE_CR | |
163 | /<lf> PCRE_NEWLINE_LF | |
164 | /<crlf> PCRE_NEWLINE_CRLF | |
165 | /<anycrlf> PCRE_NEWLINE_ANYCRLF | |
166 | /<any> PCRE_NEWLINE_ANY | |
6bf342e1 PH |
167 | |
168 | Those specifying line ending sequencess are literal strings as shown. | |
169 | This example sets multiline matching with CRLF as the line ending | |
170 | sequence: | |
aa41d2de | 171 | |
6bf342e1 PH |
172 | /^abc/m<crlf> |
173 | ||
174 | Details of the meanings of these PCRE options are given in the pcreapi | |
175 | documentation. | |
aa41d2de PH |
176 | |
177 | Finding all matches in a string | |
178 | ||
179 | Searching for all possible matches within each subject string can be | |
180 | requested by the /g or /G modifier. After finding a match, PCRE is | |
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181 | called again to search the remainder of the subject string. The differ- |
182 | ence between /g and /G is that the former uses the startoffset argument | |
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183 | to pcre_exec() to start searching at a new point within the entire |
184 | string (which is in effect what Perl does), whereas the latter passes | |
185 | over a shortened substring. This makes a difference to the matching | |
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186 | process if the pattern begins with a lookbehind assertion (including \b |
187 | or \B). | |
188 | ||
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189 | If any call to pcre_exec() in a /g or /G sequence matches an empty |
190 | string, the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED | |
191 | flags set in order to search for another, non-empty, match at the same | |
192 | point. If this second match fails, the start offset is advanced by | |
193 | one, and the normal match is retried. This imitates the way Perl han- | |
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194 | dles such cases when using the /g modifier or the split() function. |
195 | ||
aa41d2de PH |
196 | Other modifiers |
197 | ||
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198 | There are yet more modifiers for controlling the way pcretest operates. |
199 | ||
aa41d2de PH |
200 | The /+ modifier requests that as well as outputting the substring that |
201 | matched the entire pattern, pcretest should in addition output the | |
202 | remainder of the subject string. This is useful for tests where the | |
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203 | subject contains multiple copies of the same substring. |
204 | ||
6bf342e1 | 205 | The /B modifier is a debugging feature. It requests that pcretest out- |
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206 | put a representation of the compiled byte code after compilation. Nor- |
207 | mally this information contains length and offset values; however, if | |
208 | /Z is also present, this data is replaced by spaces. This is a special | |
209 | feature for use in the automatic test scripts; it ensures that the same | |
210 | output is generated for different internal link sizes. | |
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211 | |
212 | The /L modifier must be followed directly by the name of a locale, for | |
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213 | example, |
214 | ||
215 | /pattern/Lfr_FR | |
216 | ||
217 | For this reason, it must be the last modifier. The given locale is set, | |
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218 | pcre_maketables() is called to build a set of character tables for the |
219 | locale, and this is then passed to pcre_compile() when compiling the | |
220 | regular expression. Without an /L modifier, NULL is passed as the | |
221 | tables pointer; that is, /L applies only to the expression on which it | |
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222 | appears. |
223 | ||
6bf342e1 PH |
224 | The /I modifier requests that pcretest output information about the |
225 | compiled pattern (whether it is anchored, has a fixed first character, | |
226 | and so on). It does this by calling pcre_fullinfo() after compiling a | |
227 | pattern. If the pattern is studied, the results of that are also out- | |
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228 | put. |
229 | ||
6bf342e1 PH |
230 | The /D modifier is a PCRE debugging feature, and is equivalent to /BI, |
231 | that is, both the /B and the /I modifiers. | |
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232 | |
233 | The /F modifier causes pcretest to flip the byte order of the fields in | |
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234 | the compiled pattern that contain 2-byte and 4-byte numbers. This |
235 | facility is for testing the feature in PCRE that allows it to execute | |
495ae4b0 | 236 | patterns that were compiled on a host with a different endianness. This |
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237 | feature is not available when the POSIX interface to PCRE is being |
238 | used, that is, when the /P pattern modifier is specified. See also the | |
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239 | section about saving and reloading compiled patterns below. |
240 | ||
6bf342e1 | 241 | The /S modifier causes pcre_study() to be called after the expression |
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242 | has been compiled, and the results used when the expression is matched. |
243 | ||
6bf342e1 | 244 | The /M modifier causes the size of memory block used to hold the com- |
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245 | piled pattern to be output. |
246 | ||
6bf342e1 PH |
247 | The /P modifier causes pcretest to call PCRE via the POSIX wrapper API |
248 | rather than its native API. When this is done, all other modifiers | |
249 | except /i, /m, and /+ are ignored. REG_ICASE is set if /i is present, | |
250 | and REG_NEWLINE is set if /m is present. The wrapper functions force | |
251 | PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set. | |
495ae4b0 | 252 | |
6bf342e1 PH |
253 | The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option |
254 | set. This turns on support for UTF-8 character handling in PCRE, pro- | |
255 | vided that it was compiled with this support enabled. This modifier | |
495ae4b0 PH |
256 | also causes any non-printing characters in output strings to be printed |
257 | using the \x{hh...} notation if they are valid UTF-8 sequences. | |
258 | ||
6bf342e1 PH |
259 | If the /? modifier is used with /8, it causes pcretest to call |
260 | pcre_compile() with the PCRE_NO_UTF8_CHECK option, to suppress the | |
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261 | checking of the string for UTF-8 validity. |
262 | ||
263 | ||
264 | DATA LINES | |
265 | ||
6bf342e1 PH |
266 | Before each data line is passed to pcre_exec(), leading and trailing |
267 | whitespace is removed, and it is then scanned for \ escapes. Some of | |
268 | these are pretty esoteric features, intended for checking out some of | |
269 | the more complicated features of PCRE. If you are just testing "ordi- | |
270 | nary" regular expressions, you probably don't need any of these. The | |
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271 | following escapes are recognized: |
272 | ||
6bf342e1 PH |
273 | \a alarm (BEL, \x07) |
274 | \b backspace (\x08) | |
275 | \e escape (\x27) | |
276 | \f formfeed (\x0c) | |
277 | \n newline (\x0a) | |
aa41d2de PH |
278 | \qdd set the PCRE_MATCH_LIMIT limit to dd |
279 | (any number of digits) | |
6bf342e1 PH |
280 | \r carriage return (\x0d) |
281 | \t tab (\x09) | |
282 | \v vertical tab (\x0b) | |
495ae4b0 PH |
283 | \nnn octal character (up to 3 octal digits) |
284 | \xhh hexadecimal character (up to 2 hex digits) | |
285 | \x{hh...} hexadecimal character, any number of digits | |
286 | in UTF-8 mode | |
287 | \A pass the PCRE_ANCHORED option to pcre_exec() | |
aa41d2de | 288 | or pcre_dfa_exec() |
495ae4b0 | 289 | \B pass the PCRE_NOTBOL option to pcre_exec() |
aa41d2de | 290 | or pcre_dfa_exec() |
495ae4b0 PH |
291 | \Cdd call pcre_copy_substring() for substring dd |
292 | after a successful match (number less than 32) | |
293 | \Cname call pcre_copy_named_substring() for substring | |
294 | "name" after a successful match (name termin- | |
295 | ated by next non alphanumeric character) | |
296 | \C+ show the current captured substrings at callout | |
297 | time | |
298 | \C- do not supply a callout function | |
299 | \C!n return 1 instead of 0 when callout number n is | |
300 | reached | |
301 | \C!n!m return 1 instead of 0 when callout number n is | |
302 | reached for the nth time | |
303 | \C*n pass the number n (may be negative) as callout | |
304 | data; this is used as the callout return value | |
8ac170f3 PH |
305 | \D use the pcre_dfa_exec() match function |
306 | \F only shortest match for pcre_dfa_exec() | |
495ae4b0 PH |
307 | \Gdd call pcre_get_substring() for substring dd |
308 | after a successful match (number less than 32) | |
309 | \Gname call pcre_get_named_substring() for substring | |
310 | "name" after a successful match (name termin- | |
311 | ated by next non-alphanumeric character) | |
312 | \L call pcre_get_substringlist() after a | |
313 | successful match | |
aa41d2de PH |
314 | \M discover the minimum MATCH_LIMIT and |
315 | MATCH_LIMIT_RECURSION settings | |
495ae4b0 | 316 | \N pass the PCRE_NOTEMPTY option to pcre_exec() |
aa41d2de | 317 | or pcre_dfa_exec() |
495ae4b0 PH |
318 | \Odd set the size of the output vector passed to |
319 | pcre_exec() to dd (any number of digits) | |
320 | \P pass the PCRE_PARTIAL option to pcre_exec() | |
8ac170f3 | 321 | or pcre_dfa_exec() |
aa41d2de PH |
322 | \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd |
323 | (any number of digits) | |
8ac170f3 | 324 | \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec() |
495ae4b0 PH |
325 | \S output details of memory get/free calls during matching |
326 | \Z pass the PCRE_NOTEOL option to pcre_exec() | |
aa41d2de | 327 | or pcre_dfa_exec() |
495ae4b0 | 328 | \? pass the PCRE_NO_UTF8_CHECK option to |
aa41d2de | 329 | pcre_exec() or pcre_dfa_exec() |
495ae4b0 PH |
330 | \>dd start the match at offset dd (any number of digits); |
331 | this sets the startoffset argument for pcre_exec() | |
aa41d2de PH |
332 | or pcre_dfa_exec() |
333 | \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec() | |
334 | or pcre_dfa_exec() | |
335 | \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec() | |
336 | or pcre_dfa_exec() | |
337 | \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec() | |
338 | or pcre_dfa_exec() | |
64f2600a PH |
339 | \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec() |
340 | or pcre_dfa_exec() | |
6bf342e1 PH |
341 | \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec() |
342 | or pcre_dfa_exec() | |
495ae4b0 | 343 | |
6bf342e1 PH |
344 | The escapes that specify line ending sequences are literal strings, |
345 | exactly as shown. No more than one newline setting should be present in | |
346 | any data line. | |
347 | ||
348 | A backslash followed by anything else just escapes the anything else. | |
349 | If the very last character is a backslash, it is ignored. This gives a | |
350 | way of passing an empty line as data, since a real empty line termi- | |
351 | nates the data input. | |
495ae4b0 | 352 | |
8ac170f3 | 353 | If \M is present, pcretest calls pcre_exec() several times, with dif- |
aa41d2de PH |
354 | ferent values in the match_limit and match_limit_recursion fields of |
355 | the pcre_extra data structure, until it finds the minimum numbers for | |
356 | each parameter that allow pcre_exec() to complete. The match_limit num- | |
357 | ber is a measure of the amount of backtracking that takes place, and | |
358 | checking it out can be instructive. For most simple matches, the number | |
359 | is quite small, but for patterns with very large numbers of matching | |
360 | possibilities, it can become large very quickly with increasing length | |
361 | of subject string. The match_limit_recursion number is a measure of how | |
362 | much stack (or, if PCRE is compiled with NO_RECURSE, how much heap) | |
363 | memory is needed to complete the match attempt. | |
364 | ||
365 | When \O is used, the value specified may be higher or lower than the | |
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366 | size set by the -O command line option (or defaulted to 45); \O applies |
367 | only to the call of pcre_exec() for the line in which it appears. | |
368 | ||
aa41d2de PH |
369 | If the /P modifier was present on the pattern, causing the POSIX wrap- |
370 | per API to be used, the only option-setting sequences that have any | |
371 | effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively, | |
372 | to be passed to regexec(). | |
495ae4b0 | 373 | |
8ac170f3 PH |
374 | The use of \x{hh...} to represent UTF-8 characters is not dependent on |
375 | the use of the /8 modifier on the pattern. It is recognized always. | |
376 | There may be any number of hexadecimal digits inside the braces. The | |
377 | result is from one to six bytes, encoded according to the UTF-8 rules. | |
378 | ||
379 | ||
380 | THE ALTERNATIVE MATCHING FUNCTION | |
381 | ||
382 | By default, pcretest uses the standard PCRE matching function, | |
383 | pcre_exec() to match each data line. From release 6.0, PCRE supports an | |
384 | alternative matching function, pcre_dfa_test(), which operates in a | |
385 | different way, and has some restrictions. The differences between the | |
386 | two functions are described in the pcrematching documentation. | |
387 | ||
388 | If a data line contains the \D escape sequence, or if the command line | |
389 | contains the -dfa option, the alternative matching function is called. | |
390 | This function finds all possible matches at a given point. If, however, | |
391 | the \F escape sequence is present in the data line, it stops after the | |
392 | first match is found. This is always the shortest possible match. | |
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393 | |
394 | ||
8ac170f3 PH |
395 | DEFAULT OUTPUT FROM PCRETEST |
396 | ||
397 | This section describes the output when the normal matching function, | |
398 | pcre_exec(), is being used. | |
495ae4b0 PH |
399 | |
400 | When a match succeeds, pcretest outputs the list of captured substrings | |
401 | that pcre_exec() returns, starting with number 0 for the string that | |
402 | matched the whole pattern. Otherwise, it outputs "No match" or "Partial | |
403 | match" when pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR- | |
404 | TIAL, respectively, and otherwise the PCRE negative error number. Here | |
405 | is an example of an interactive pcretest run. | |
406 | ||
407 | $ pcretest | |
6bf342e1 | 408 | PCRE version 7.0 30-Nov-2006 |
495ae4b0 PH |
409 | |
410 | re> /^abc(\d+)/ | |
411 | data> abc123 | |
412 | 0: abc123 | |
413 | 1: 123 | |
414 | data> xyz | |
415 | No match | |
416 | ||
417 | If the strings contain any non-printing characters, they are output as | |
418 | \0x escapes, or as \x{...} escapes if the /8 modifier was present on | |
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419 | the pattern. See below for the definition of non-printing characters. |
420 | If the pattern has the /+ modifier, the output for substring 0 is fol- | |
421 | lowed by the the rest of the subject string, identified by "0+" like | |
422 | this: | |
495ae4b0 PH |
423 | |
424 | re> /cat/+ | |
425 | data> cataract | |
426 | 0: cat | |
427 | 0+ aract | |
428 | ||
6bf342e1 | 429 | If the pattern has the /g or /G modifier, the results of successive |
495ae4b0 PH |
430 | matching attempts are output in sequence, like this: |
431 | ||
432 | re> /\Bi(\w\w)/g | |
433 | data> Mississippi | |
434 | 0: iss | |
435 | 1: ss | |
436 | 0: iss | |
437 | 1: ss | |
438 | 0: ipp | |
439 | 1: pp | |
440 | ||
441 | "No match" is output only if the first match attempt fails. | |
442 | ||
6bf342e1 PH |
443 | If any of the sequences \C, \G, or \L are present in a data line that |
444 | is successfully matched, the substrings extracted by the convenience | |
495ae4b0 PH |
445 | functions are output with C, G, or L after the string number instead of |
446 | a colon. This is in addition to the normal full list. The string length | |
6bf342e1 | 447 | (that is, the return from the extraction function) is given in paren- |
495ae4b0 PH |
448 | theses after each string for \C and \G. |
449 | ||
6bf342e1 | 450 | Note that whereas patterns can be continued over several lines (a plain |
495ae4b0 | 451 | ">" prompt is used for continuations), data lines may not. However new- |
6bf342e1 PH |
452 | lines can be included in data by means of the \n escape (or \r, \r\n, |
453 | etc., depending on the newline sequence setting). | |
495ae4b0 PH |
454 | |
455 | ||
8ac170f3 PH |
456 | OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION |
457 | ||
6bf342e1 PH |
458 | When the alternative matching function, pcre_dfa_exec(), is used (by |
459 | means of the \D escape sequence or the -dfa command line option), the | |
460 | output consists of a list of all the matches that start at the first | |
8ac170f3 PH |
461 | point in the subject where there is at least one match. For example: |
462 | ||
463 | re> /(tang|tangerine|tan)/ | |
464 | data> yellow tangerine\D | |
465 | 0: tangerine | |
466 | 1: tang | |
467 | 2: tan | |
468 | ||
6bf342e1 PH |
469 | (Using the normal matching function on this data finds only "tang".) |
470 | The longest matching string is always given first (and numbered zero). | |
8ac170f3 | 471 | |
6bf342e1 PH |
472 | If /g is present on the pattern, the search for further matches resumes |
473 | at the end of the longest match. For example: | |
8ac170f3 PH |
474 | |
475 | re> /(tang|tangerine|tan)/g | |
476 | data> yellow tangerine and tangy sultana\D | |
477 | 0: tangerine | |
478 | 1: tang | |
479 | 2: tan | |
480 | 0: tang | |
481 | 1: tan | |
482 | 0: tan | |
483 | ||
6bf342e1 PH |
484 | Since the matching function does not support substring capture, the |
485 | escape sequences that are concerned with captured substrings are not | |
8ac170f3 PH |
486 | relevant. |
487 | ||
488 | ||
489 | RESTARTING AFTER A PARTIAL MATCH | |
490 | ||
491 | When the alternative matching function has given the PCRE_ERROR_PARTIAL | |
6bf342e1 PH |
492 | return, indicating that the subject partially matched the pattern, you |
493 | can restart the match with additional subject data by means of the \R | |
8ac170f3 PH |
494 | escape sequence. For example: |
495 | ||
64f2600a | 496 | re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/ |
8ac170f3 PH |
497 | data> 23ja\P\D |
498 | Partial match: 23ja | |
499 | data> n05\R\D | |
500 | 0: n05 | |
501 | ||
6bf342e1 | 502 | For further information about partial matching, see the pcrepartial |
8ac170f3 PH |
503 | documentation. |
504 | ||
505 | ||
495ae4b0 PH |
506 | CALLOUTS |
507 | ||
6bf342e1 PH |
508 | If the pattern contains any callout requests, pcretest's callout func- |
509 | tion is called during matching. This works with both matching func- | |
8ac170f3 | 510 | tions. By default, the called function displays the callout number, the |
6bf342e1 | 511 | start and current positions in the text at the callout time, and the |
8ac170f3 | 512 | next pattern item to be tested. For example, the output |
495ae4b0 PH |
513 | |
514 | --->pqrabcdef | |
515 | 0 ^ ^ \d | |
516 | ||
6bf342e1 PH |
517 | indicates that callout number 0 occurred for a match attempt starting |
518 | at the fourth character of the subject string, when the pointer was at | |
519 | the seventh character of the data, and when the next pattern item was | |
520 | \d. Just one circumflex is output if the start and current positions | |
495ae4b0 PH |
521 | are the same. |
522 | ||
523 | Callouts numbered 255 are assumed to be automatic callouts, inserted as | |
6bf342e1 PH |
524 | a result of the /C pattern modifier. In this case, instead of showing |
525 | the callout number, the offset in the pattern, preceded by a plus, is | |
495ae4b0 PH |
526 | output. For example: |
527 | ||
528 | re> /\d?[A-E]\*/C | |
529 | data> E* | |
530 | --->E* | |
531 | +0 ^ \d? | |
532 | +3 ^ [A-E] | |
533 | +8 ^^ \* | |
534 | +10 ^ ^ | |
535 | 0: E* | |
536 | ||
6bf342e1 PH |
537 | The callout function in pcretest returns zero (carry on matching) by |
538 | default, but you can use a \C item in a data line (as described above) | |
495ae4b0 PH |
539 | to change this. |
540 | ||
6bf342e1 PH |
541 | Inserting callouts can be helpful when using pcretest to check compli- |
542 | cated regular expressions. For further information about callouts, see | |
495ae4b0 PH |
543 | the pcrecallout documentation. |
544 | ||
545 | ||
6bf342e1 PH |
546 | NON-PRINTING CHARACTERS |
547 | ||
548 | When pcretest is outputting text in the compiled version of a pattern, | |
549 | bytes other than 32-126 are always treated as non-printing characters | |
550 | are are therefore shown as hex escapes. | |
551 | ||
552 | When pcretest is outputting text that is a matched part of a subject | |
553 | string, it behaves in the same way, unless a different locale has been | |
554 | set for the pattern (using the /L modifier). In this case, the | |
555 | isprint() function to distinguish printing and non-printing characters. | |
556 | ||
557 | ||
495ae4b0 PH |
558 | SAVING AND RELOADING COMPILED PATTERNS |
559 | ||
6bf342e1 | 560 | The facilities described in this section are not available when the |
495ae4b0 PH |
561 | POSIX inteface to PCRE is being used, that is, when the /P pattern mod- |
562 | ifier is specified. | |
563 | ||
564 | When the POSIX interface is not in use, you can cause pcretest to write | |
6bf342e1 | 565 | a compiled pattern to a file, by following the modifiers with > and a |
495ae4b0 PH |
566 | file name. For example: |
567 | ||
568 | /pattern/im >/some/file | |
569 | ||
6bf342e1 | 570 | See the pcreprecompile documentation for a discussion about saving and |
495ae4b0 PH |
571 | re-using compiled patterns. |
572 | ||
6bf342e1 PH |
573 | The data that is written is binary. The first eight bytes are the |
574 | length of the compiled pattern data followed by the length of the | |
575 | optional study data, each written as four bytes in big-endian order | |
576 | (most significant byte first). If there is no study data (either the | |
495ae4b0 | 577 | pattern was not studied, or studying did not return any data), the sec- |
6bf342e1 | 578 | ond length is zero. The lengths are followed by an exact copy of the |
495ae4b0 | 579 | compiled pattern. If there is additional study data, this follows imme- |
6bf342e1 | 580 | diately after the compiled pattern. After writing the file, pcretest |
495ae4b0 PH |
581 | expects to read a new pattern. |
582 | ||
583 | A saved pattern can be reloaded into pcretest by specifing < and a file | |
6bf342e1 PH |
584 | name instead of a pattern. The name of the file must not contain a < |
585 | character, as otherwise pcretest will interpret the line as a pattern | |
495ae4b0 PH |
586 | delimited by < characters. For example: |
587 | ||
588 | re> </some/file | |
589 | Compiled regex loaded from /some/file | |
590 | No study data | |
591 | ||
6bf342e1 | 592 | When the pattern has been loaded, pcretest proceeds to read data lines |
495ae4b0 PH |
593 | in the usual way. |
594 | ||
6bf342e1 PH |
595 | You can copy a file written by pcretest to a different host and reload |
596 | it there, even if the new host has opposite endianness to the one on | |
597 | which the pattern was compiled. For example, you can compile on an i86 | |
495ae4b0 PH |
598 | machine and run on a SPARC machine. |
599 | ||
6bf342e1 PH |
600 | File names for saving and reloading can be absolute or relative, but |
601 | note that the shell facility of expanding a file name that starts with | |
495ae4b0 PH |
602 | a tilde (~) is not available. |
603 | ||
6bf342e1 PH |
604 | The ability to save and reload files in pcretest is intended for test- |
605 | ing and experimentation. It is not intended for production use because | |
606 | only a single pattern can be written to a file. Furthermore, there is | |
607 | no facility for supplying custom character tables for use with a | |
608 | reloaded pattern. If the original pattern was compiled with custom | |
609 | tables, an attempt to match a subject string using a reloaded pattern | |
610 | is likely to cause pcretest to crash. Finally, if you attempt to load | |
495ae4b0 PH |
611 | a file that is not in the correct format, the result is undefined. |
612 | ||
613 | ||
6bf342e1 PH |
614 | SEE ALSO |
615 | ||
616 | pcre(3), pcreapi(3), pcrecallout(3), pcrematching(3), pcrepartial(d), | |
617 | pcrepattern(3), pcreprecompile(3). | |
618 | ||
619 | ||
495ae4b0 PH |
620 | AUTHOR |
621 | ||
8ac170f3 | 622 | Philip Hazel |
64f2600a | 623 | University Computing Service |
6bf342e1 | 624 | Cambridge CB2 3QH, England. |
495ae4b0 | 625 | |
64f2600a PH |
626 | |
627 | REVISION | |
628 | ||
629 | Last updated: 24 April 2007 | |
630 | Copyright (c) 1997-2007 University of Cambridge. |