Annotation of embedaddon/pcre/doc/pcretest.txt, revision 1.1.1.1
1.1 misho 1: PCRETEST(1) PCRETEST(1)
2:
3:
4: NAME
5: pcretest - a program for testing Perl-compatible regular expressions.
6:
7:
8: SYNOPSIS
9:
10: pcretest [options] [input file [output file]]
11:
12: pcretest was written as a test program for the PCRE regular expression
13: library itself, but it can also be used for experimenting with regular
14: expressions. This document describes the features of the test program;
15: for details of the regular expressions themselves, see the pcrepattern
16: documentation. For details of the PCRE library function calls and their
17: options, see the pcreapi documentation. The input for pcretest is a
18: sequence of regular expression patterns and strings to be matched, as
19: described below. The output shows the result of each match. Options on
20: the command line and the patterns control PCRE options and exactly what
21: is output.
22:
23:
24: COMMAND LINE OPTIONS
25:
26: -b Behave as if each pattern has the /B (show byte code) modi-
27: fier; the internal form is output after compilation.
28:
29: -C Output the version number of the PCRE library, and all avail-
30: able information about the optional features that are
31: included, and then exit.
32:
33: -d Behave as if each pattern has the /D (debug) modifier; the
34: internal form and information about the compiled pattern is
35: output after compilation; -d is equivalent to -b -i.
36:
37: -dfa Behave as if each data line contains the \D escape sequence;
38: this causes the alternative matching function,
39: pcre_dfa_exec(), to be used instead of the standard
40: pcre_exec() function (more detail is given below).
41:
42: -help Output a brief summary these options and then exit.
43:
44: -i Behave as if each pattern has the /I modifier; information
45: about the compiled pattern is given after compilation.
46:
47: -M Behave as if each data line contains the \M escape sequence;
48: this causes PCRE to discover the minimum MATCH_LIMIT and
49: MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
50: edly with different limits.
51:
52: -m Output the size of each compiled pattern after it has been
53: compiled. This is equivalent to adding /M to each regular
54: expression.
55:
56: -o osize Set the number of elements in the output vector that is used
57: when calling pcre_exec() or pcre_dfa_exec() to be osize. The
58: default value is 45, which is enough for 14 capturing subex-
59: pressions for pcre_exec() or 22 different matches for
60: pcre_dfa_exec(). The vector size can be changed for individ-
61: ual matching calls by including \O in the data line (see
62: below).
63:
64: -p Behave as if each pattern has the /P modifier; the POSIX
65: wrapper API is used to call PCRE. None of the other options
66: has any effect when -p is set.
67:
68: -q Do not output the version number of pcretest at the start of
69: execution.
70:
71: -S size On Unix-like systems, set the size of the run-time stack to
72: size megabytes.
73:
74: -s or -s+ Behave as if each pattern has the /S modifier; in other
75: words, force each pattern to be studied. If -s+ is used, the
76: PCRE_STUDY_JIT_COMPILE flag is passed to pcre_study(), caus-
77: ing just-in-time optimization to be set up if it is avail-
78: able. If the /I or /D option is present on a pattern
79: (requesting output about the compiled pattern), information
80: about the result of studying is not included when studying is
81: caused only by -s and neither -i nor -d is present on the
82: command line. This behaviour means that the output from tests
83: that are run with and without -s should be identical, except
84: when options that output information about the actual running
85: of a match are set. The -M, -t, and -tm options, which give
86: information about resources used, are likely to produce dif-
87: ferent output with and without -s. Output may also differ if
88: the /C option is present on an individual pattern. This uses
89: callouts to trace the the matching process, and this may be
90: different between studied and non-studied patterns. If the
91: pattern contains (*MARK) items there may also be differences,
92: for the same reason. The -s command line option can be over-
93: ridden for specific patterns that should never be studied
94: (see the /S pattern modifier below).
95:
96: -t Run each compile, study, and match many times with a timer,
97: and output resulting time per compile or match (in millisec-
98: onds). Do not set -m with -t, because you will then get the
99: size output a zillion times, and the timing will be dis-
100: torted. You can control the number of iterations that are
101: used for timing by following -t with a number (as a separate
102: item on the command line). For example, "-t 1000" would iter-
103: ate 1000 times. The default is to iterate 500000 times.
104:
105: -tm This is like -t except that it times only the matching phase,
106: not the compile or study phases.
107:
108:
109: DESCRIPTION
110:
111: If pcretest is given two filename arguments, it reads from the first
112: and writes to the second. If it is given only one filename argument, it
113: reads from that file and writes to stdout. Otherwise, it reads from
114: stdin and writes to stdout, and prompts for each line of input, using
115: "re>" to prompt for regular expressions, and "data>" to prompt for data
116: lines.
117:
118: When pcretest is built, a configuration option can specify that it
119: should be linked with the libreadline library. When this is done, if
120: the input is from a terminal, it is read using the readline() function.
121: This provides line-editing and history facilities. The output from the
122: -help option states whether or not readline() will be used.
123:
124: The program handles any number of sets of input on a single input file.
125: Each set starts with a regular expression, and continues with any num-
126: ber of data lines to be matched against the pattern.
127:
128: Each data line is matched separately and independently. If you want to
129: do multi-line matches, you have to use the \n escape sequence (or \r or
130: \r\n, etc., depending on the newline setting) in a single line of input
131: to encode the newline sequences. There is no limit on the length of
132: data lines; the input buffer is automatically extended if it is too
133: small.
134:
135: An empty line signals the end of the data lines, at which point a new
136: regular expression is read. The regular expressions are given enclosed
137: in any non-alphanumeric delimiters other than backslash, for example:
138:
139: /(a|bc)x+yz/
140:
141: White space before the initial delimiter is ignored. A regular expres-
142: sion may be continued over several input lines, in which case the new-
143: line characters are included within it. It is possible to include the
144: delimiter within the pattern by escaping it, for example
145:
146: /abc\/def/
147:
148: If you do so, the escape and the delimiter form part of the pattern,
149: but since delimiters are always non-alphanumeric, this does not affect
150: its interpretation. If the terminating delimiter is immediately fol-
151: lowed by a backslash, for example,
152:
153: /abc/\
154:
155: then a backslash is added to the end of the pattern. This is done to
156: provide a way of testing the error condition that arises if a pattern
157: finishes with a backslash, because
158:
159: /abc\/
160:
161: is interpreted as the first line of a pattern that starts with "abc/",
162: causing pcretest to read the next line as a continuation of the regular
163: expression.
164:
165:
166: PATTERN MODIFIERS
167:
168: A pattern may be followed by any number of modifiers, which are mostly
169: single characters. Following Perl usage, these are referred to below
170: as, for example, "the /i modifier", even though the delimiter of the
171: pattern need not always be a slash, and no slash is used when writing
172: modifiers. White space may appear between the final pattern delimiter
173: and the first modifier, and between the modifiers themselves.
174:
175: The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
176: PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre_com-
177: pile() is called. These four modifier letters have the same effect as
178: they do in Perl. For example:
179:
180: /caseless/i
181:
182: The following table shows additional modifiers for setting PCRE com-
183: pile-time options that do not correspond to anything in Perl:
184:
185: /8 PCRE_UTF8
186: /? PCRE_NO_UTF8_CHECK
187: /A PCRE_ANCHORED
188: /C PCRE_AUTO_CALLOUT
189: /E PCRE_DOLLAR_ENDONLY
190: /f PCRE_FIRSTLINE
191: /J PCRE_DUPNAMES
192: /N PCRE_NO_AUTO_CAPTURE
193: /U PCRE_UNGREEDY
194: /W PCRE_UCP
195: /X PCRE_EXTRA
196: /Y PCRE_NO_START_OPTIMIZE
197: /<JS> PCRE_JAVASCRIPT_COMPAT
198: /<cr> PCRE_NEWLINE_CR
199: /<lf> PCRE_NEWLINE_LF
200: /<crlf> PCRE_NEWLINE_CRLF
201: /<anycrlf> PCRE_NEWLINE_ANYCRLF
202: /<any> PCRE_NEWLINE_ANY
203: /<bsr_anycrlf> PCRE_BSR_ANYCRLF
204: /<bsr_unicode> PCRE_BSR_UNICODE
205:
206: The modifiers that are enclosed in angle brackets are literal strings
207: as shown, including the angle brackets, but the letters within can be
208: in either case. This example sets multiline matching with CRLF as the
209: line ending sequence:
210:
211: /^abc/m<CRLF>
212:
213: As well as turning on the PCRE_UTF8 option, the /8 modifier also causes
214: any non-printing characters in output strings to be printed using the
215: \x{hh...} notation if they are valid UTF-8 sequences. Full details of
216: the PCRE options are given in the pcreapi documentation.
217:
218: Finding all matches in a string
219:
220: Searching for all possible matches within each subject string can be
221: requested by the /g or /G modifier. After finding a match, PCRE is
222: called again to search the remainder of the subject string. The differ-
223: ence between /g and /G is that the former uses the startoffset argument
224: to pcre_exec() to start searching at a new point within the entire
225: string (which is in effect what Perl does), whereas the latter passes
226: over a shortened substring. This makes a difference to the matching
227: process if the pattern begins with a lookbehind assertion (including \b
228: or \B).
229:
230: If any call to pcre_exec() in a /g or /G sequence matches an empty
231: string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
232: PCRE_ANCHORED flags set in order to search for another, non-empty,
233: match at the same point. If this second match fails, the start offset
234: is advanced, and the normal match is retried. This imitates the way
235: Perl handles such cases when using the /g modifier or the split() func-
236: tion. Normally, the start offset is advanced by one character, but if
237: the newline convention recognizes CRLF as a newline, and the current
238: character is CR followed by LF, an advance of two is used.
239:
240: Other modifiers
241:
242: There are yet more modifiers for controlling the way pcretest operates.
243:
244: The /+ modifier requests that as well as outputting the substring that
245: matched the entire pattern, pcretest should in addition output the
246: remainder of the subject string. This is useful for tests where the
247: subject contains multiple copies of the same substring. If the + modi-
248: fier appears twice, the same action is taken for captured substrings.
249: In each case the remainder is output on the following line with a plus
250: character following the capture number. Note that this modifier must
251: not immediately follow the /S modifier because /S+ has another meaning.
252:
253: The /= modifier requests that the values of all potential captured
254: parentheses be output after a match by pcre_exec(). By default, only
255: those up to the highest one actually used in the match are output (cor-
256: responding to the return code from pcre_exec()). Values in the offsets
257: vector corresponding to higher numbers should be set to -1, and these
258: are output as "<unset>". This modifier gives a way of checking that
259: this is happening.
260:
261: The /B modifier is a debugging feature. It requests that pcretest out-
262: put a representation of the compiled byte code after compilation. Nor-
263: mally this information contains length and offset values; however, if
264: /Z is also present, this data is replaced by spaces. This is a special
265: feature for use in the automatic test scripts; it ensures that the same
266: output is generated for different internal link sizes.
267:
268: The /D modifier is a PCRE debugging feature, and is equivalent to /BI,
269: that is, both the /B and the /I modifiers.
270:
271: The /F modifier causes pcretest to flip the byte order of the fields in
272: the compiled pattern that contain 2-byte and 4-byte numbers. This
273: facility is for testing the feature in PCRE that allows it to execute
274: patterns that were compiled on a host with a different endianness. This
275: feature is not available when the POSIX interface to PCRE is being
276: used, that is, when the /P pattern modifier is specified. See also the
277: section about saving and reloading compiled patterns below.
278:
279: The /I modifier requests that pcretest output information about the
280: compiled pattern (whether it is anchored, has a fixed first character,
281: and so on). It does this by calling pcre_fullinfo() after compiling a
282: pattern. If the pattern is studied, the results of that are also out-
283: put.
284:
285: The /K modifier requests pcretest to show names from backtracking con-
286: trol verbs that are returned from calls to pcre_exec(). It causes
287: pcretest to create a pcre_extra block if one has not already been cre-
288: ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
289: the mark field within it, every time that pcre_exec() is called. If the
290: variable that the mark field points to is non-NULL for a match, non-
291: match, or partial match, pcretest prints the string to which it points.
292: For a match, this is shown on a line by itself, tagged with "MK:". For
293: a non-match it is added to the message.
294:
295: The /L modifier must be followed directly by the name of a locale, for
296: example,
297:
298: /pattern/Lfr_FR
299:
300: For this reason, it must be the last modifier. The given locale is set,
301: pcre_maketables() is called to build a set of character tables for the
302: locale, and this is then passed to pcre_compile() when compiling the
303: regular expression. Without an /L (or /T) modifier, NULL is passed as
304: the tables pointer; that is, /L applies only to the expression on which
305: it appears.
306:
307: The /M modifier causes the size of memory block used to hold the com-
308: piled pattern to be output. This does not include the size of the pcre
309: block; it is just the actual compiled data. If the pattern is success-
310: fully studied with the PCRE_STUDY_JIT_COMPILE option, the size of the
311: JIT compiled code is also output.
312:
313: If the /S modifier appears once, it causes pcre_study() to be called
314: after the expression has been compiled, and the results used when the
315: expression is matched. If /S appears twice, it suppresses studying,
316: even if it was requested externally by the -s command line option. This
317: makes it possible to specify that certain patterns are always studied,
318: and others are never studied, independently of -s. This feature is used
319: in the test files in a few cases where the output is different when the
320: pattern is studied.
321:
322: If the /S modifier is immediately followed by a + character, the call
323: to pcre_study() is made with the PCRE_STUDY_JIT_COMPILE option,
324: requesting just-in-time optimization support if it is available. Note
325: that there is also a /+ modifier; it must not be given immediately
326: after /S because this will be misinterpreted. If JIT studying is suc-
327: cessful, it will automatically be used when pcre_exec() is run, except
328: when incompatible run-time options are specified. These include the
329: partial matching options; a complete list is given in the pcrejit docu-
330: mentation. See also the \J escape sequence below for a way of setting
331: the size of the JIT stack.
332:
333: The /T modifier must be followed by a single digit. It causes a spe-
334: cific set of built-in character tables to be passed to pcre_compile().
335: It is used in the standard PCRE tests to check behaviour with different
336: character tables. The digit specifies the tables as follows:
337:
338: 0 the default ASCII tables, as distributed in
339: pcre_chartables.c.dist
340: 1 a set of tables defining ISO 8859 characters
341:
342: In table 1, some characters whose codes are greater than 128 are iden-
343: tified as letters, digits, spaces, etc.
344:
345: Using the POSIX wrapper API
346:
347: The /P modifier causes pcretest to call PCRE via the POSIX wrapper API
348: rather than its native API. When /P is set, the following modifiers set
349: options for the regcomp() function:
350:
351: /i REG_ICASE
352: /m REG_NEWLINE
353: /N REG_NOSUB
354: /s REG_DOTALL )
355: /U REG_UNGREEDY ) These options are not part of
356: /W REG_UCP ) the POSIX standard
357: /8 REG_UTF8 )
358:
359: The /+ modifier works as described above. All other modifiers are
360: ignored.
361:
362:
363: DATA LINES
364:
365: Before each data line is passed to pcre_exec(), leading and trailing
366: white space is removed, and it is then scanned for \ escapes. Some of
367: these are pretty esoteric features, intended for checking out some of
368: the more complicated features of PCRE. If you are just testing "ordi-
369: nary" regular expressions, you probably don't need any of these. The
370: following escapes are recognized:
371:
372: \a alarm (BEL, \x07)
373: \b backspace (\x08)
374: \e escape (\x27)
375: \f form feed (\x0c)
376: \n newline (\x0a)
377: \qdd set the PCRE_MATCH_LIMIT limit to dd
378: (any number of digits)
379: \r carriage return (\x0d)
380: \t tab (\x09)
381: \v vertical tab (\x0b)
382: \nnn octal character (up to 3 octal digits)
383: always a byte unless > 255 in UTF-8 mode
384: \xhh hexadecimal byte (up to 2 hex digits)
385: \x{hh...} hexadecimal character, any number of digits
386: in UTF-8 mode
387: \A pass the PCRE_ANCHORED option to pcre_exec()
388: or pcre_dfa_exec()
389: \B pass the PCRE_NOTBOL option to pcre_exec()
390: or pcre_dfa_exec()
391: \Cdd call pcre_copy_substring() for substring dd
392: after a successful match (number less than 32)
393: \Cname call pcre_copy_named_substring() for substring
394: "name" after a successful match (name termin-
395: ated by next non alphanumeric character)
396: \C+ show the current captured substrings at callout
397: time
398: \C- do not supply a callout function
399: \C!n return 1 instead of 0 when callout number n is
400: reached
401: \C!n!m return 1 instead of 0 when callout number n is
402: reached for the nth time
403: \C*n pass the number n (may be negative) as callout
404: data; this is used as the callout return value
405: \D use the pcre_dfa_exec() match function
406: \F only shortest match for pcre_dfa_exec()
407: \Gdd call pcre_get_substring() for substring dd
408: after a successful match (number less than 32)
409: \Gname call pcre_get_named_substring() for substring
410: "name" after a successful match (name termin-
411: ated by next non-alphanumeric character)
412: \Jdd set up a JIT stack of dd kilobytes maximum (any
413: number of digits)
414: \L call pcre_get_substringlist() after a
415: successful match
416: \M discover the minimum MATCH_LIMIT and
417: MATCH_LIMIT_RECURSION settings
418: \N pass the PCRE_NOTEMPTY option to pcre_exec()
419: or pcre_dfa_exec(); if used twice, pass the
420: PCRE_NOTEMPTY_ATSTART option
421: \Odd set the size of the output vector passed to
422: pcre_exec() to dd (any number of digits)
423: \P pass the PCRE_PARTIAL_SOFT option to pcre_exec()
424: or pcre_dfa_exec(); if used twice, pass the
425: PCRE_PARTIAL_HARD option
426: \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
427: (any number of digits)
428: \R pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
429: \S output details of memory get/free calls during matching
430: \Y pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
431: or pcre_dfa_exec()
432: \Z pass the PCRE_NOTEOL option to pcre_exec()
433: or pcre_dfa_exec()
434: \? pass the PCRE_NO_UTF8_CHECK option to
435: pcre_exec() or pcre_dfa_exec()
436: \>dd start the match at offset dd (optional "-"; then
437: any number of digits); this sets the startoffset
438: argument for pcre_exec() or pcre_dfa_exec()
439: \<cr> pass the PCRE_NEWLINE_CR option to pcre_exec()
440: or pcre_dfa_exec()
441: \<lf> pass the PCRE_NEWLINE_LF option to pcre_exec()
442: or pcre_dfa_exec()
443: \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre_exec()
444: or pcre_dfa_exec()
445: \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
446: or pcre_dfa_exec()
447: \<any> pass the PCRE_NEWLINE_ANY option to pcre_exec()
448: or pcre_dfa_exec()
449:
450: Note that \xhh always specifies one byte, even in UTF-8 mode; this
451: makes it possible to construct invalid UTF-8 sequences for testing pur-
452: poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
453: UTF-8 mode, generating more than one byte if the value is greater than
454: 127. When not in UTF-8 mode, it generates one byte for values less than
455: 256, and causes an error for greater values.
456:
457: The escapes that specify line ending sequences are literal strings,
458: exactly as shown. No more than one newline setting should be present in
459: any data line.
460:
461: A backslash followed by anything else just escapes the anything else.
462: If the very last character is a backslash, it is ignored. This gives a
463: way of passing an empty line as data, since a real empty line termi-
464: nates the data input.
465:
466: The \J escape provides a way of setting the maximum stack size that is
467: used by the just-in-time optimization code. It is ignored if JIT opti-
468: mization is not being used. Providing a stack that is larger than the
469: default 32K is necessary only for very complicated patterns.
470:
471: If \M is present, pcretest calls pcre_exec() several times, with dif-
472: ferent values in the match_limit and match_limit_recursion fields of
473: the pcre_extra data structure, until it finds the minimum numbers for
474: each parameter that allow pcre_exec() to complete without error.
475: Because this is testing a specific feature of the normal interpretive
476: pcre_exec() execution, the use of any JIT optimization that might have
477: been set up by the /S+ qualifier of -s+ option is disabled.
478:
479: The match_limit number is a measure of the amount of backtracking that
480: takes place, and checking it out can be instructive. For most simple
481: matches, the number is quite small, but for patterns with very large
482: numbers of matching possibilities, it can become large very quickly
483: with increasing length of subject string. The match_limit_recursion
484: number is a measure of how much stack (or, if PCRE is compiled with
485: NO_RECURSE, how much heap) memory is needed to complete the match
486: attempt.
487:
488: When \O is used, the value specified may be higher or lower than the
489: size set by the -O command line option (or defaulted to 45); \O applies
490: only to the call of pcre_exec() for the line in which it appears.
491:
492: If the /P modifier was present on the pattern, causing the POSIX wrap-
493: per API to be used, the only option-setting sequences that have any
494: effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and
495: REG_NOTEOL, respectively, to be passed to regexec().
496:
497: The use of \x{hh...} to represent UTF-8 characters is not dependent on
498: the use of the /8 modifier on the pattern. It is recognized always.
499: There may be any number of hexadecimal digits inside the braces. The
500: result is from one to six bytes, encoded according to the original
501: UTF-8 rules of RFC 2279. This allows for values in the range 0 to
502: 0x7FFFFFFF. Note that not all of those are valid Unicode code points,
503: or indeed valid UTF-8 characters according to the later rules in RFC
504: 3629.
505:
506:
507: THE ALTERNATIVE MATCHING FUNCTION
508:
509: By default, pcretest uses the standard PCRE matching function,
510: pcre_exec() to match each data line. From release 6.0, PCRE supports an
511: alternative matching function, pcre_dfa_test(), which operates in a
512: different way, and has some restrictions. The differences between the
513: two functions are described in the pcrematching documentation.
514:
515: If a data line contains the \D escape sequence, or if the command line
516: contains the -dfa option, the alternative matching function is called.
517: This function finds all possible matches at a given point. If, however,
518: the \F escape sequence is present in the data line, it stops after the
519: first match is found. This is always the shortest possible match.
520:
521:
522: DEFAULT OUTPUT FROM PCRETEST
523:
524: This section describes the output when the normal matching function,
525: pcre_exec(), is being used.
526:
527: When a match succeeds, pcretest outputs the list of captured substrings
528: that pcre_exec() returns, starting with number 0 for the string that
529: matched the whole pattern. Otherwise, it outputs "No match" when the
530: return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
531: tially matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
532: (Note that this is the entire substring that was inspected during the
533: partial match; it may include characters before the actual match start
534: if a lookbehind assertion, \K, \b, or \B was involved.) For any other
535: return, pcretest outputs the PCRE negative error number and a short
536: descriptive phrase. If the error is a failed UTF-8 string check, the
537: byte offset of the start of the failing character and the reason code
538: are also output, provided that the size of the output vector is at
539: least two. Here is an example of an interactive pcretest run.
540:
541: $ pcretest
542: PCRE version 8.13 2011-04-30
543:
544: re> /^abc(\d+)/
545: data> abc123
546: 0: abc123
547: 1: 123
548: data> xyz
549: No match
550:
551: Unset capturing substrings that are not followed by one that is set are
552: not returned by pcre_exec(), and are not shown by pcretest. In the fol-
553: lowing example, there are two capturing substrings, but when the first
554: data line is matched, the second, unset substring is not shown. An
555: "internal" unset substring is shown as "<unset>", as for the second
556: data line.
557:
558: re> /(a)|(b)/
559: data> a
560: 0: a
561: 1: a
562: data> b
563: 0: b
564: 1: <unset>
565: 2: b
566:
567: If the strings contain any non-printing characters, they are output as
568: \0x escapes, or as \x{...} escapes if the /8 modifier was present on
569: the pattern. See below for the definition of non-printing characters.
570: If the pattern has the /+ modifier, the output for substring 0 is fol-
571: lowed by the the rest of the subject string, identified by "0+" like
572: this:
573:
574: re> /cat/+
575: data> cataract
576: 0: cat
577: 0+ aract
578:
579: If the pattern has the /g or /G modifier, the results of successive
580: matching attempts are output in sequence, like this:
581:
582: re> /\Bi(\w\w)/g
583: data> Mississippi
584: 0: iss
585: 1: ss
586: 0: iss
587: 1: ss
588: 0: ipp
589: 1: pp
590:
591: "No match" is output only if the first match attempt fails. Here is an
592: example of a failure message (the offset 4 that is specified by \>4 is
593: past the end of the subject string):
594:
595: re> /xyz/
596: data> xyz\>4
597: Error -24 (bad offset value)
598:
599: If any of the sequences \C, \G, or \L are present in a data line that
600: is successfully matched, the substrings extracted by the convenience
601: functions are output with C, G, or L after the string number instead of
602: a colon. This is in addition to the normal full list. The string length
603: (that is, the return from the extraction function) is given in paren-
604: theses after each string for \C and \G.
605:
606: Note that whereas patterns can be continued over several lines (a plain
607: ">" prompt is used for continuations), data lines may not. However new-
608: lines can be included in data by means of the \n escape (or \r, \r\n,
609: etc., depending on the newline sequence setting).
610:
611:
612: OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
613:
614: When the alternative matching function, pcre_dfa_exec(), is used (by
615: means of the \D escape sequence or the -dfa command line option), the
616: output consists of a list of all the matches that start at the first
617: point in the subject where there is at least one match. For example:
618:
619: re> /(tang|tangerine|tan)/
620: data> yellow tangerine\D
621: 0: tangerine
622: 1: tang
623: 2: tan
624:
625: (Using the normal matching function on this data finds only "tang".)
626: The longest matching string is always given first (and numbered zero).
627: After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
628: lowed by the partially matching substring. (Note that this is the
629: entire substring that was inspected during the partial match; it may
630: include characters before the actual match start if a lookbehind asser-
631: tion, \K, \b, or \B was involved.)
632:
633: If /g is present on the pattern, the search for further matches resumes
634: at the end of the longest match. For example:
635:
636: re> /(tang|tangerine|tan)/g
637: data> yellow tangerine and tangy sultana\D
638: 0: tangerine
639: 1: tang
640: 2: tan
641: 0: tang
642: 1: tan
643: 0: tan
644:
645: Since the matching function does not support substring capture, the
646: escape sequences that are concerned with captured substrings are not
647: relevant.
648:
649:
650: RESTARTING AFTER A PARTIAL MATCH
651:
652: When the alternative matching function has given the PCRE_ERROR_PARTIAL
653: return, indicating that the subject partially matched the pattern, you
654: can restart the match with additional subject data by means of the \R
655: escape sequence. For example:
656:
657: re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
658: data> 23ja\P\D
659: Partial match: 23ja
660: data> n05\R\D
661: 0: n05
662:
663: For further information about partial matching, see the pcrepartial
664: documentation.
665:
666:
667: CALLOUTS
668:
669: If the pattern contains any callout requests, pcretest's callout func-
670: tion is called during matching. This works with both matching func-
671: tions. By default, the called function displays the callout number, the
672: start and current positions in the text at the callout time, and the
673: next pattern item to be tested. For example, the output
674:
675: --->pqrabcdef
676: 0 ^ ^ \d
677:
678: indicates that callout number 0 occurred for a match attempt starting
679: at the fourth character of the subject string, when the pointer was at
680: the seventh character of the data, and when the next pattern item was
681: \d. Just one circumflex is output if the start and current positions
682: are the same.
683:
684: Callouts numbered 255 are assumed to be automatic callouts, inserted as
685: a result of the /C pattern modifier. In this case, instead of showing
686: the callout number, the offset in the pattern, preceded by a plus, is
687: output. For example:
688:
689: re> /\d?[A-E]\*/C
690: data> E*
691: --->E*
692: +0 ^ \d?
693: +3 ^ [A-E]
694: +8 ^^ \*
695: +10 ^ ^
696: 0: E*
697:
698: If a pattern contains (*MARK) items, an additional line is output when-
699: ever a change of latest mark is passed to the callout function. For
700: example:
701:
702: re> /a(*MARK:X)bc/C
703: data> abc
704: --->abc
705: +0 ^ a
706: +1 ^^ (*MARK:X)
707: +10 ^^ b
708: Latest Mark: X
709: +11 ^ ^ c
710: +12 ^ ^
711: 0: abc
712:
713: The mark changes between matching "a" and "b", but stays the same for
714: the rest of the match, so nothing more is output. If, as a result of
715: backtracking, the mark reverts to being unset, the text "<unset>" is
716: output.
717:
718: The callout function in pcretest returns zero (carry on matching) by
719: default, but you can use a \C item in a data line (as described above)
720: to change this and other parameters of the callout.
721:
722: Inserting callouts can be helpful when using pcretest to check compli-
723: cated regular expressions. For further information about callouts, see
724: the pcrecallout documentation.
725:
726:
727: NON-PRINTING CHARACTERS
728:
729: When pcretest is outputting text in the compiled version of a pattern,
730: bytes other than 32-126 are always treated as non-printing characters
731: are are therefore shown as hex escapes.
732:
733: When pcretest is outputting text that is a matched part of a subject
734: string, it behaves in the same way, unless a different locale has been
735: set for the pattern (using the /L modifier). In this case, the
736: isprint() function to distinguish printing and non-printing characters.
737:
738:
739: SAVING AND RELOADING COMPILED PATTERNS
740:
741: The facilities described in this section are not available when the
742: POSIX interface to PCRE is being used, that is, when the /P pattern
743: modifier is specified.
744:
745: When the POSIX interface is not in use, you can cause pcretest to write
746: a compiled pattern to a file, by following the modifiers with > and a
747: file name. For example:
748:
749: /pattern/im >/some/file
750:
751: See the pcreprecompile documentation for a discussion about saving and
752: re-using compiled patterns. Note that if the pattern was successfully
753: studied with JIT optimization, the JIT data cannot be saved.
754:
755: The data that is written is binary. The first eight bytes are the
756: length of the compiled pattern data followed by the length of the
757: optional study data, each written as four bytes in big-endian order
758: (most significant byte first). If there is no study data (either the
759: pattern was not studied, or studying did not return any data), the sec-
760: ond length is zero. The lengths are followed by an exact copy of the
761: compiled pattern. If there is additional study data, this (excluding
762: any JIT data) follows immediately after the compiled pattern. After
763: writing the file, pcretest expects to read a new pattern.
764:
765: A saved pattern can be reloaded into pcretest by specifying < and a
766: file name instead of a pattern. The name of the file must not contain a
767: < character, as otherwise pcretest will interpret the line as a pattern
768: delimited by < characters. For example:
769:
770: re> </some/file
771: Compiled pattern loaded from /some/file
772: No study data
773:
774: If the pattern was previously studied with the JIT optimization, the
775: JIT information cannot be saved and restored, and so is lost. When the
776: pattern has been loaded, pcretest proceeds to read data lines in the
777: usual way.
778:
779: You can copy a file written by pcretest to a different host and reload
780: it there, even if the new host has opposite endianness to the one on
781: which the pattern was compiled. For example, you can compile on an i86
782: machine and run on a SPARC machine.
783:
784: File names for saving and reloading can be absolute or relative, but
785: note that the shell facility of expanding a file name that starts with
786: a tilde (~) is not available.
787:
788: The ability to save and reload files in pcretest is intended for test-
789: ing and experimentation. It is not intended for production use because
790: only a single pattern can be written to a file. Furthermore, there is
791: no facility for supplying custom character tables for use with a
792: reloaded pattern. If the original pattern was compiled with custom
793: tables, an attempt to match a subject string using a reloaded pattern
794: is likely to cause pcretest to crash. Finally, if you attempt to load
795: a file that is not in the correct format, the result is undefined.
796:
797:
798: SEE ALSO
799:
800: pcre(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematching(3), pcrepar-
801: tial(d), pcrepattern(3), pcreprecompile(3).
802:
803:
804: AUTHOR
805:
806: Philip Hazel
807: University Computing Service
808: Cambridge CB2 3QH, England.
809:
810:
811: REVISION
812:
813: Last updated: 02 December 2011
814: Copyright (c) 1997-2011 University of Cambridge.
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>
![[BACK]](/icons/cvsweb/back.gif){kind=icon}
Return to pcretest.txt CVS log ![[TXT]](/icons/cvsweb/text.gif){kind=icon}
![[DIR]](/icons/cvsweb/dir.gif){kind=icon}
Up to [ELWIX - Embedded LightWeight unIX -] / embedaddon / pcre / doc