Annotation of embedaddon/pcre/doc/pcretest.1, revision 1.1.1.1
1.1 misho 1: .TH PCRETEST 1
2: .SH NAME
3: pcretest - a program for testing Perl-compatible regular expressions.
4: .SH SYNOPSIS
5: .rs
6: .sp
7: .B pcretest "[options] [input file [output file]]"
8: .sp
9: \fBpcretest\fP was written as a test program for the PCRE regular expression
10: library itself, but it can also be used for experimenting with regular
11: expressions. This document describes the features of the test program; for
12: details of the regular expressions themselves, see the
13: .\" HREF
14: \fBpcrepattern\fP
15: .\"
16: documentation. For details of the PCRE library function calls and their
17: options, see the
18: .\" HREF
19: \fBpcreapi\fP
20: .\"
21: documentation. The input for \fBpcretest\fP is a sequence of regular expression
22: patterns and strings to be matched, as described below. The output shows the
23: result of each match. Options on the command line and the patterns control PCRE
24: options and exactly what is output.
25: .
26: .
27: .SH COMMAND LINE OPTIONS
28: .rs
29: .TP 10
30: \fB-b\fP
31: Behave as if each pattern has the \fB/B\fP (show byte code) modifier; the
32: internal form is output after compilation.
33: .TP 10
34: \fB-C\fP
35: Output the version number of the PCRE library, and all available information
36: about the optional features that are included, and then exit.
37: .TP 10
38: \fB-d\fP
39: Behave as if each pattern has the \fB/D\fP (debug) modifier; the internal
40: form and information about the compiled pattern is output after compilation;
41: \fB-d\fP is equivalent to \fB-b -i\fP.
42: .TP 10
43: \fB-dfa\fP
44: Behave as if each data line contains the \eD escape sequence; this causes the
45: alternative matching function, \fBpcre_dfa_exec()\fP, to be used instead of the
46: standard \fBpcre_exec()\fP function (more detail is given below).
47: .TP 10
48: \fB-help\fP
49: Output a brief summary these options and then exit.
50: .TP 10
51: \fB-i\fP
52: Behave as if each pattern has the \fB/I\fP modifier; information about the
53: compiled pattern is given after compilation.
54: .TP 10
55: \fB-M\fP
56: Behave as if each data line contains the \eM escape sequence; this causes
57: PCRE to discover the minimum MATCH_LIMIT and MATCH_LIMIT_RECURSION settings by
58: calling \fBpcre_exec()\fP repeatedly with different limits.
59: .TP 10
60: \fB-m\fP
61: Output the size of each compiled pattern after it has been compiled. This is
62: equivalent to adding \fB/M\fP to each regular expression.
63: .TP 10
64: \fB-o\fP \fIosize\fP
65: Set the number of elements in the output vector that is used when calling
66: \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP to be \fIosize\fP. The default value
67: is 45, which is enough for 14 capturing subexpressions for \fBpcre_exec()\fP or
68: 22 different matches for \fBpcre_dfa_exec()\fP. The vector size can be
69: changed for individual matching calls by including \eO in the data line (see
70: below).
71: .TP 10
72: \fB-p\fP
73: Behave as if each pattern has the \fB/P\fP modifier; the POSIX wrapper API is
74: used to call PCRE. None of the other options has any effect when \fB-p\fP is
75: set.
76: .TP 10
77: \fB-q\fP
78: Do not output the version number of \fBpcretest\fP at the start of execution.
79: .TP 10
80: \fB-S\fP \fIsize\fP
81: On Unix-like systems, set the size of the run-time stack to \fIsize\fP
82: megabytes.
83: .TP 10
84: \fB-s\fP or \fB-s+\fP
85: Behave as if each pattern has the \fB/S\fP modifier; in other words, force each
86: pattern to be studied. If \fB-s+\fP is used, the PCRE_STUDY_JIT_COMPILE flag is
87: passed to \fBpcre_study()\fP, causing just-in-time optimization to be set up if
88: it is available. If the \fB/I\fP or \fB/D\fP option is present on a pattern
89: (requesting output about the compiled pattern), information about the result of
90: studying is not included when studying is caused only by \fB-s\fP and neither
91: \fB-i\fP nor \fB-d\fP is present on the command line. This behaviour means that
92: the output from tests that are run with and without \fB-s\fP should be
93: identical, except when options that output information about the actual running
94: of a match are set. The \fB-M\fP, \fB-t\fP, and \fB-tm\fP options, which give
95: information about resources used, are likely to produce different output with
96: and without \fB-s\fP. Output may also differ if the \fB/C\fP option is present
97: on an individual pattern. This uses callouts to trace the the matching process,
98: and this may be different between studied and non-studied patterns. If the
99: pattern contains (*MARK) items there may also be differences, for the same
100: reason. The \fB-s\fP command line option can be overridden for specific
101: patterns that should never be studied (see the \fB/S\fP pattern modifier
102: below).
103: .TP 10
104: \fB-t\fP
105: Run each compile, study, and match many times with a timer, and output
106: resulting time per compile or match (in milliseconds). Do not set \fB-m\fP with
107: \fB-t\fP, because you will then get the size output a zillion times, and the
108: timing will be distorted. You can control the number of iterations that are
109: used for timing by following \fB-t\fP with a number (as a separate item on the
110: command line). For example, "-t 1000" would iterate 1000 times. The default is
111: to iterate 500000 times.
112: .TP 10
113: \fB-tm\fP
114: This is like \fB-t\fP except that it times only the matching phase, not the
115: compile or study phases.
116: .
117: .
118: .SH DESCRIPTION
119: .rs
120: .sp
121: If \fBpcretest\fP is given two filename arguments, it reads from the first and
122: writes to the second. If it is given only one filename argument, it reads from
123: that file and writes to stdout. Otherwise, it reads from stdin and writes to
124: stdout, and prompts for each line of input, using "re>" to prompt for regular
125: expressions, and "data>" to prompt for data lines.
126: .P
127: When \fBpcretest\fP is built, a configuration option can specify that it should
128: be linked with the \fBlibreadline\fP library. When this is done, if the input
129: is from a terminal, it is read using the \fBreadline()\fP function. This
130: provides line-editing and history facilities. The output from the \fB-help\fP
131: option states whether or not \fBreadline()\fP will be used.
132: .P
133: The program handles any number of sets of input on a single input file. Each
134: set starts with a regular expression, and continues with any number of data
135: lines to be matched against the pattern.
136: .P
137: Each data line is matched separately and independently. If you want to do
138: multi-line matches, you have to use the \en escape sequence (or \er or \er\en,
139: etc., depending on the newline setting) in a single line of input to encode the
140: newline sequences. There is no limit on the length of data lines; the input
141: buffer is automatically extended if it is too small.
142: .P
143: An empty line signals the end of the data lines, at which point a new regular
144: expression is read. The regular expressions are given enclosed in any
145: non-alphanumeric delimiters other than backslash, for example:
146: .sp
147: /(a|bc)x+yz/
148: .sp
149: White space before the initial delimiter is ignored. A regular expression may
150: be continued over several input lines, in which case the newline characters are
151: included within it. It is possible to include the delimiter within the pattern
152: by escaping it, for example
153: .sp
154: /abc\e/def/
155: .sp
156: If you do so, the escape and the delimiter form part of the pattern, but since
157: delimiters are always non-alphanumeric, this does not affect its interpretation.
158: If the terminating delimiter is immediately followed by a backslash, for
159: example,
160: .sp
161: /abc/\e
162: .sp
163: then a backslash is added to the end of the pattern. This is done to provide a
164: way of testing the error condition that arises if a pattern finishes with a
165: backslash, because
166: .sp
167: /abc\e/
168: .sp
169: is interpreted as the first line of a pattern that starts with "abc/", causing
170: pcretest to read the next line as a continuation of the regular expression.
171: .
172: .
173: .SH "PATTERN MODIFIERS"
174: .rs
175: .sp
176: A pattern may be followed by any number of modifiers, which are mostly single
177: characters. Following Perl usage, these are referred to below as, for example,
178: "the \fB/i\fP modifier", even though the delimiter of the pattern need not
179: always be a slash, and no slash is used when writing modifiers. White space may
180: appear between the final pattern delimiter and the first modifier, and between
181: the modifiers themselves.
182: .P
183: The \fB/i\fP, \fB/m\fP, \fB/s\fP, and \fB/x\fP modifiers set the PCRE_CASELESS,
184: PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when
185: \fBpcre_compile()\fP is called. These four modifier letters have the same
186: effect as they do in Perl. For example:
187: .sp
188: /caseless/i
189: .sp
190: The following table shows additional modifiers for setting PCRE compile-time
191: options that do not correspond to anything in Perl:
192: .sp
193: \fB/8\fP PCRE_UTF8
194: \fB/?\fP PCRE_NO_UTF8_CHECK
195: \fB/A\fP PCRE_ANCHORED
196: \fB/C\fP PCRE_AUTO_CALLOUT
197: \fB/E\fP PCRE_DOLLAR_ENDONLY
198: \fB/f\fP PCRE_FIRSTLINE
199: \fB/J\fP PCRE_DUPNAMES
200: \fB/N\fP PCRE_NO_AUTO_CAPTURE
201: \fB/U\fP PCRE_UNGREEDY
202: \fB/W\fP PCRE_UCP
203: \fB/X\fP PCRE_EXTRA
204: \fB/Y\fP PCRE_NO_START_OPTIMIZE
205: \fB/<JS>\fP PCRE_JAVASCRIPT_COMPAT
206: \fB/<cr>\fP PCRE_NEWLINE_CR
207: \fB/<lf>\fP PCRE_NEWLINE_LF
208: \fB/<crlf>\fP PCRE_NEWLINE_CRLF
209: \fB/<anycrlf>\fP PCRE_NEWLINE_ANYCRLF
210: \fB/<any>\fP PCRE_NEWLINE_ANY
211: \fB/<bsr_anycrlf>\fP PCRE_BSR_ANYCRLF
212: \fB/<bsr_unicode>\fP PCRE_BSR_UNICODE
213: .sp
214: The modifiers that are enclosed in angle brackets are literal strings as shown,
215: including the angle brackets, but the letters within can be in either case.
216: This example sets multiline matching with CRLF as the line ending sequence:
217: .sp
218: /^abc/m<CRLF>
219: .sp
220: As well as turning on the PCRE_UTF8 option, the \fB/8\fP modifier also causes
221: any non-printing characters in output strings to be printed using the
222: \ex{hh...} notation if they are valid UTF-8 sequences. Full details of the PCRE
223: options are given in the
224: .\" HREF
225: \fBpcreapi\fP
226: .\"
227: documentation.
228: .
229: .
230: .SS "Finding all matches in a string"
231: .rs
232: .sp
233: Searching for all possible matches within each subject string can be requested
234: by the \fB/g\fP or \fB/G\fP modifier. After finding a match, PCRE is called
235: again to search the remainder of the subject string. The difference between
236: \fB/g\fP and \fB/G\fP is that the former uses the \fIstartoffset\fP argument to
237: \fBpcre_exec()\fP to start searching at a new point within the entire string
238: (which is in effect what Perl does), whereas the latter passes over a shortened
239: substring. This makes a difference to the matching process if the pattern
240: begins with a lookbehind assertion (including \eb or \eB).
241: .P
242: If any call to \fBpcre_exec()\fP in a \fB/g\fP or \fB/G\fP sequence matches an
243: empty string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
244: PCRE_ANCHORED flags set in order to search for another, non-empty, match at the
245: same point. If this second match fails, the start offset is advanced, and the
246: normal match is retried. This imitates the way Perl handles such cases when
247: using the \fB/g\fP modifier or the \fBsplit()\fP function. Normally, the start
248: offset is advanced by one character, but if the newline convention recognizes
249: CRLF as a newline, and the current character is CR followed by LF, an advance
250: of two is used.
251: .
252: .
253: .SS "Other modifiers"
254: .rs
255: .sp
256: There are yet more modifiers for controlling the way \fBpcretest\fP
257: operates.
258: .P
259: The \fB/+\fP modifier requests that as well as outputting the substring that
260: matched the entire pattern, \fBpcretest\fP should in addition output the
261: remainder of the subject string. This is useful for tests where the subject
262: contains multiple copies of the same substring. If the \fB+\fP modifier appears
263: twice, the same action is taken for captured substrings. In each case the
264: remainder is output on the following line with a plus character following the
265: capture number. Note that this modifier must not immediately follow the /S
266: modifier because /S+ has another meaning.
267: .P
268: The \fB/=\fP modifier requests that the values of all potential captured
269: parentheses be output after a match by \fBpcre_exec()\fP. By default, only
270: those up to the highest one actually used in the match are output
271: (corresponding to the return code from \fBpcre_exec()\fP). Values in the
272: offsets vector corresponding to higher numbers should be set to -1, and these
273: are output as "<unset>". This modifier gives a way of checking that this is
274: happening.
275: .P
276: The \fB/B\fP modifier is a debugging feature. It requests that \fBpcretest\fP
277: output a representation of the compiled byte code after compilation. Normally
278: this information contains length and offset values; however, if \fB/Z\fP is
279: also present, this data is replaced by spaces. This is a special feature for
280: use in the automatic test scripts; it ensures that the same output is generated
281: for different internal link sizes.
282: .P
283: The \fB/D\fP modifier is a PCRE debugging feature, and is equivalent to
284: \fB/BI\fP, that is, both the \fB/B\fP and the \fB/I\fP modifiers.
285: .P
286: The \fB/F\fP modifier causes \fBpcretest\fP to flip the byte order of the
287: fields in the compiled pattern that contain 2-byte and 4-byte numbers. This
288: facility is for testing the feature in PCRE that allows it to execute patterns
289: that were compiled on a host with a different endianness. This feature is not
290: available when the POSIX interface to PCRE is being used, that is, when the
291: \fB/P\fP pattern modifier is specified. See also the section about saving and
292: reloading compiled patterns below.
293: .P
294: The \fB/I\fP modifier requests that \fBpcretest\fP output information about the
295: compiled pattern (whether it is anchored, has a fixed first character, and
296: so on). It does this by calling \fBpcre_fullinfo()\fP after compiling a
297: pattern. If the pattern is studied, the results of that are also output.
298: .P
299: The \fB/K\fP modifier requests \fBpcretest\fP to show names from backtracking
300: control verbs that are returned from calls to \fBpcre_exec()\fP. It causes
301: \fBpcretest\fP to create a \fBpcre_extra\fP block if one has not already been
302: created by a call to \fBpcre_study()\fP, and to set the PCRE_EXTRA_MARK flag
303: and the \fBmark\fP field within it, every time that \fBpcre_exec()\fP is
304: called. If the variable that the \fBmark\fP field points to is non-NULL for a
305: match, non-match, or partial match, \fBpcretest\fP prints the string to which
306: it points. For a match, this is shown on a line by itself, tagged with "MK:".
307: For a non-match it is added to the message.
308: .P
309: The \fB/L\fP modifier must be followed directly by the name of a locale, for
310: example,
311: .sp
312: /pattern/Lfr_FR
313: .sp
314: For this reason, it must be the last modifier. The given locale is set,
315: \fBpcre_maketables()\fP is called to build a set of character tables for the
316: locale, and this is then passed to \fBpcre_compile()\fP when compiling the
317: regular expression. Without an \fB/L\fP (or \fB/T\fP) modifier, NULL is passed
318: as the tables pointer; that is, \fB/L\fP applies only to the expression on
319: which it appears.
320: .P
321: The \fB/M\fP modifier causes the size of memory block used to hold the compiled
322: pattern to be output. This does not include the size of the \fBpcre\fP block;
323: it is just the actual compiled data. If the pattern is successfully studied
324: with the PCRE_STUDY_JIT_COMPILE option, the size of the JIT compiled code is
325: also output.
326: .P
327: If the \fB/S\fP modifier appears once, it causes \fBpcre_study()\fP to be
328: called after the expression has been compiled, and the results used when the
329: expression is matched. If \fB/S\fP appears twice, it suppresses studying, even
330: if it was requested externally by the \fB-s\fP command line option. This makes
331: it possible to specify that certain patterns are always studied, and others are
332: never studied, independently of \fB-s\fP. This feature is used in the test
333: files in a few cases where the output is different when the pattern is studied.
334: .P
335: If the \fB/S\fP modifier is immediately followed by a + character, the call to
336: \fBpcre_study()\fP is made with the PCRE_STUDY_JIT_COMPILE option, requesting
337: just-in-time optimization support if it is available. Note that there is also a
338: \fB/+\fP modifier; it must not be given immediately after \fB/S\fP because this
339: will be misinterpreted. If JIT studying is successful, it will automatically be
340: used when \fBpcre_exec()\fP is run, except when incompatible run-time options
341: are specified. These include the partial matching options; a complete list is
342: given in the
343: .\" HREF
344: \fBpcrejit\fP
345: .\"
346: documentation. See also the \fB\eJ\fP escape sequence below for a way of
347: setting the size of the JIT stack.
348: .P
349: The \fB/T\fP modifier must be followed by a single digit. It causes a specific
350: set of built-in character tables to be passed to \fBpcre_compile()\fP. It is
351: used in the standard PCRE tests to check behaviour with different character
352: tables. The digit specifies the tables as follows:
353: .sp
354: 0 the default ASCII tables, as distributed in
355: pcre_chartables.c.dist
356: 1 a set of tables defining ISO 8859 characters
357: .sp
358: In table 1, some characters whose codes are greater than 128 are identified as
359: letters, digits, spaces, etc.
360: .
361: .
362: .SS "Using the POSIX wrapper API"
363: .rs
364: .sp
365: The \fB/P\fP modifier causes \fBpcretest\fP to call PCRE via the POSIX wrapper
366: API rather than its native API. When \fB/P\fP is set, the following modifiers
367: set options for the \fBregcomp()\fP function:
368: .sp
369: /i REG_ICASE
370: /m REG_NEWLINE
371: /N REG_NOSUB
372: /s REG_DOTALL )
373: /U REG_UNGREEDY ) These options are not part of
374: /W REG_UCP ) the POSIX standard
375: /8 REG_UTF8 )
376: .sp
377: The \fB/+\fP modifier works as described above. All other modifiers are
378: ignored.
379: .
380: .
381: .SH "DATA LINES"
382: .rs
383: .sp
384: Before each data line is passed to \fBpcre_exec()\fP, leading and trailing
385: white space is removed, and it is then scanned for \e escapes. Some of these
386: are pretty esoteric features, intended for checking out some of the more
387: complicated features of PCRE. If you are just testing "ordinary" regular
388: expressions, you probably don't need any of these. The following escapes are
389: recognized:
390: .sp
391: \ea alarm (BEL, \ex07)
392: \eb backspace (\ex08)
393: \ee escape (\ex27)
394: \ef form feed (\ex0c)
395: \en newline (\ex0a)
396: .\" JOIN
397: \eqdd set the PCRE_MATCH_LIMIT limit to dd
398: (any number of digits)
399: \er carriage return (\ex0d)
400: \et tab (\ex09)
401: \ev vertical tab (\ex0b)
402: \ennn octal character (up to 3 octal digits)
403: always a byte unless > 255 in UTF-8 mode
404: \exhh hexadecimal byte (up to 2 hex digits)
405: .\" JOIN
406: \ex{hh...} hexadecimal character, any number of digits
407: in UTF-8 mode
408: .\" JOIN
409: \eA pass the PCRE_ANCHORED option to \fBpcre_exec()\fP
410: or \fBpcre_dfa_exec()\fP
411: .\" JOIN
412: \eB pass the PCRE_NOTBOL option to \fBpcre_exec()\fP
413: or \fBpcre_dfa_exec()\fP
414: .\" JOIN
415: \eCdd call pcre_copy_substring() for substring dd
416: after a successful match (number less than 32)
417: .\" JOIN
418: \eCname call pcre_copy_named_substring() for substring
419: "name" after a successful match (name termin-
420: ated by next non alphanumeric character)
421: .\" JOIN
422: \eC+ show the current captured substrings at callout
423: time
424: \eC- do not supply a callout function
425: .\" JOIN
426: \eC!n return 1 instead of 0 when callout number n is
427: reached
428: .\" JOIN
429: \eC!n!m return 1 instead of 0 when callout number n is
430: reached for the nth time
431: .\" JOIN
432: \eC*n pass the number n (may be negative) as callout
433: data; this is used as the callout return value
434: \eD use the \fBpcre_dfa_exec()\fP match function
435: \eF only shortest match for \fBpcre_dfa_exec()\fP
436: .\" JOIN
437: \eGdd call pcre_get_substring() for substring dd
438: after a successful match (number less than 32)
439: .\" JOIN
440: \eGname call pcre_get_named_substring() for substring
441: "name" after a successful match (name termin-
442: ated by next non-alphanumeric character)
443: .\" JOIN
444: \eJdd set up a JIT stack of dd kilobytes maximum (any
445: number of digits)
446: .\" JOIN
447: \eL call pcre_get_substringlist() after a
448: successful match
449: .\" JOIN
450: \eM discover the minimum MATCH_LIMIT and
451: MATCH_LIMIT_RECURSION settings
452: .\" JOIN
453: \eN pass the PCRE_NOTEMPTY option to \fBpcre_exec()\fP
454: or \fBpcre_dfa_exec()\fP; if used twice, pass the
455: PCRE_NOTEMPTY_ATSTART option
456: .\" JOIN
457: \eOdd set the size of the output vector passed to
458: \fBpcre_exec()\fP to dd (any number of digits)
459: .\" JOIN
460: \eP pass the PCRE_PARTIAL_SOFT option to \fBpcre_exec()\fP
461: or \fBpcre_dfa_exec()\fP; if used twice, pass the
462: PCRE_PARTIAL_HARD option
463: .\" JOIN
464: \eQdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd
465: (any number of digits)
466: \eR pass the PCRE_DFA_RESTART option to \fBpcre_dfa_exec()\fP
467: \eS output details of memory get/free calls during matching
468: .\" JOIN
469: \eY pass the PCRE_NO_START_OPTIMIZE option to \fBpcre_exec()\fP
470: or \fBpcre_dfa_exec()\fP
471: .\" JOIN
472: \eZ pass the PCRE_NOTEOL option to \fBpcre_exec()\fP
473: or \fBpcre_dfa_exec()\fP
474: .\" JOIN
475: \e? pass the PCRE_NO_UTF8_CHECK option to
476: \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
477: .\" JOIN
478: \e>dd start the match at offset dd (optional "-"; then
479: any number of digits); this sets the \fIstartoffset\fP
480: argument for \fBpcre_exec()\fP or \fBpcre_dfa_exec()\fP
481: .\" JOIN
482: \e<cr> pass the PCRE_NEWLINE_CR option to \fBpcre_exec()\fP
483: or \fBpcre_dfa_exec()\fP
484: .\" JOIN
485: \e<lf> pass the PCRE_NEWLINE_LF option to \fBpcre_exec()\fP
486: or \fBpcre_dfa_exec()\fP
487: .\" JOIN
488: \e<crlf> pass the PCRE_NEWLINE_CRLF option to \fBpcre_exec()\fP
489: or \fBpcre_dfa_exec()\fP
490: .\" JOIN
491: \e<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to \fBpcre_exec()\fP
492: or \fBpcre_dfa_exec()\fP
493: .\" JOIN
494: \e<any> pass the PCRE_NEWLINE_ANY option to \fBpcre_exec()\fP
495: or \fBpcre_dfa_exec()\fP
496: .sp
497: Note that \exhh always specifies one byte, even in UTF-8 mode; this makes it
498: possible to construct invalid UTF-8 sequences for testing purposes. On the
499: other hand, \ex{hh} is interpreted as a UTF-8 character in UTF-8 mode,
500: generating more than one byte if the value is greater than 127. When not in
501: UTF-8 mode, it generates one byte for values less than 256, and causes an error
502: for greater values.
503: .P
504: The escapes that specify line ending sequences are literal strings, exactly as
505: shown. No more than one newline setting should be present in any data line.
506: .P
507: A backslash followed by anything else just escapes the anything else. If
508: the very last character is a backslash, it is ignored. This gives a way of
509: passing an empty line as data, since a real empty line terminates the data
510: input.
511: .P
512: The \fB\eJ\fP escape provides a way of setting the maximum stack size that is
513: used by the just-in-time optimization code. It is ignored if JIT optimization
514: is not being used. Providing a stack that is larger than the default 32K is
515: necessary only for very complicated patterns.
516: .P
517: If \eM is present, \fBpcretest\fP calls \fBpcre_exec()\fP several times, with
518: different values in the \fImatch_limit\fP and \fImatch_limit_recursion\fP
519: fields of the \fBpcre_extra\fP data structure, until it finds the minimum
520: numbers for each parameter that allow \fBpcre_exec()\fP to complete without
521: error. Because this is testing a specific feature of the normal interpretive
522: \fBpcre_exec()\fP execution, the use of any JIT optimization that might have
523: been set up by the \fB/S+\fP qualifier of \fB-s+\fP option is disabled.
524: .P
525: The \fImatch_limit\fP number is a measure of the amount of backtracking
526: that takes place, and checking it out can be instructive. For most simple
527: matches, the number is quite small, but for patterns with very large numbers of
528: matching possibilities, it can become large very quickly with increasing length
529: of subject string. The \fImatch_limit_recursion\fP number is a measure of how
530: much stack (or, if PCRE is compiled with NO_RECURSE, how much heap) memory is
531: needed to complete the match attempt.
532: .P
533: When \eO is used, the value specified may be higher or lower than the size set
534: by the \fB-O\fP command line option (or defaulted to 45); \eO applies only to
535: the call of \fBpcre_exec()\fP for the line in which it appears.
536: .P
537: If the \fB/P\fP modifier was present on the pattern, causing the POSIX wrapper
538: API to be used, the only option-setting sequences that have any effect are \eB,
539: \eN, and \eZ, causing REG_NOTBOL, REG_NOTEMPTY, and REG_NOTEOL, respectively,
540: to be passed to \fBregexec()\fP.
541: .P
542: The use of \ex{hh...} to represent UTF-8 characters is not dependent on the use
543: of the \fB/8\fP modifier on the pattern. It is recognized always. There may be
544: any number of hexadecimal digits inside the braces. The result is from one to
545: six bytes, encoded according to the original UTF-8 rules of RFC 2279. This
546: allows for values in the range 0 to 0x7FFFFFFF. Note that not all of those are
547: valid Unicode code points, or indeed valid UTF-8 characters according to the
548: later rules in RFC 3629.
549: .
550: .
551: .SH "THE ALTERNATIVE MATCHING FUNCTION"
552: .rs
553: .sp
554: By default, \fBpcretest\fP uses the standard PCRE matching function,
555: \fBpcre_exec()\fP to match each data line. From release 6.0, PCRE supports an
556: alternative matching function, \fBpcre_dfa_test()\fP, which operates in a
557: different way, and has some restrictions. The differences between the two
558: functions are described in the
559: .\" HREF
560: \fBpcrematching\fP
561: .\"
562: documentation.
563: .P
564: If a data line contains the \eD escape sequence, or if the command line
565: contains the \fB-dfa\fP option, the alternative matching function is called.
566: This function finds all possible matches at a given point. If, however, the \eF
567: escape sequence is present in the data line, it stops after the first match is
568: found. This is always the shortest possible match.
569: .
570: .
571: .SH "DEFAULT OUTPUT FROM PCRETEST"
572: .rs
573: .sp
574: This section describes the output when the normal matching function,
575: \fBpcre_exec()\fP, is being used.
576: .P
577: When a match succeeds, \fBpcretest\fP outputs the list of captured substrings
578: that \fBpcre_exec()\fP returns, starting with number 0 for the string that
579: matched the whole pattern. Otherwise, it outputs "No match" when the return is
580: PCRE_ERROR_NOMATCH, and "Partial match:" followed by the partially matching
581: substring when \fBpcre_exec()\fP returns PCRE_ERROR_PARTIAL. (Note that this is
582: the entire substring that was inspected during the partial match; it may
583: include characters before the actual match start if a lookbehind assertion,
584: \eK, \eb, or \eB was involved.) For any other return, \fBpcretest\fP outputs
585: the PCRE negative error number and a short descriptive phrase. If the error is
586: a failed UTF-8 string check, the byte offset of the start of the failing
587: character and the reason code are also output, provided that the size of the
588: output vector is at least two. Here is an example of an interactive
589: \fBpcretest\fP run.
590: .sp
591: $ pcretest
592: PCRE version 8.13 2011-04-30
593: .sp
594: re> /^abc(\ed+)/
595: data> abc123
596: 0: abc123
597: 1: 123
598: data> xyz
599: No match
600: .sp
601: Unset capturing substrings that are not followed by one that is set are not
602: returned by \fBpcre_exec()\fP, and are not shown by \fBpcretest\fP. In the
603: following example, there are two capturing substrings, but when the first data
604: line is matched, the second, unset substring is not shown. An "internal" unset
605: substring is shown as "<unset>", as for the second data line.
606: .sp
607: re> /(a)|(b)/
608: data> a
609: 0: a
610: 1: a
611: data> b
612: 0: b
613: 1: <unset>
614: 2: b
615: .sp
616: If the strings contain any non-printing characters, they are output as \e0x
617: escapes, or as \ex{...} escapes if the \fB/8\fP modifier was present on the
618: pattern. See below for the definition of non-printing characters. If the
619: pattern has the \fB/+\fP modifier, the output for substring 0 is followed by
620: the the rest of the subject string, identified by "0+" like this:
621: .sp
622: re> /cat/+
623: data> cataract
624: 0: cat
625: 0+ aract
626: .sp
627: If the pattern has the \fB/g\fP or \fB/G\fP modifier, the results of successive
628: matching attempts are output in sequence, like this:
629: .sp
630: re> /\eBi(\ew\ew)/g
631: data> Mississippi
632: 0: iss
633: 1: ss
634: 0: iss
635: 1: ss
636: 0: ipp
637: 1: pp
638: .sp
639: "No match" is output only if the first match attempt fails. Here is an example
640: of a failure message (the offset 4 that is specified by \e>4 is past the end of
641: the subject string):
642: .sp
643: re> /xyz/
644: data> xyz\e>4
645: Error -24 (bad offset value)
646: .P
647: If any of the sequences \fB\eC\fP, \fB\eG\fP, or \fB\eL\fP are present in a
648: data line that is successfully matched, the substrings extracted by the
649: convenience functions are output with C, G, or L after the string number
650: instead of a colon. This is in addition to the normal full list. The string
651: length (that is, the return from the extraction function) is given in
652: parentheses after each string for \fB\eC\fP and \fB\eG\fP.
653: .P
654: Note that whereas patterns can be continued over several lines (a plain ">"
655: prompt is used for continuations), data lines may not. However newlines can be
656: included in data by means of the \en escape (or \er, \er\en, etc., depending on
657: the newline sequence setting).
658: .
659: .
660: .
661: .SH "OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION"
662: .rs
663: .sp
664: When the alternative matching function, \fBpcre_dfa_exec()\fP, is used (by
665: means of the \eD escape sequence or the \fB-dfa\fP command line option), the
666: output consists of a list of all the matches that start at the first point in
667: the subject where there is at least one match. For example:
668: .sp
669: re> /(tang|tangerine|tan)/
670: data> yellow tangerine\eD
671: 0: tangerine
672: 1: tang
673: 2: tan
674: .sp
675: (Using the normal matching function on this data finds only "tang".) The
676: longest matching string is always given first (and numbered zero). After a
677: PCRE_ERROR_PARTIAL return, the output is "Partial match:", followed by the
678: partially matching substring. (Note that this is the entire substring that was
679: inspected during the partial match; it may include characters before the actual
680: match start if a lookbehind assertion, \eK, \eb, or \eB was involved.)
681: .P
682: If \fB/g\fP is present on the pattern, the search for further matches resumes
683: at the end of the longest match. For example:
684: .sp
685: re> /(tang|tangerine|tan)/g
686: data> yellow tangerine and tangy sultana\eD
687: 0: tangerine
688: 1: tang
689: 2: tan
690: 0: tang
691: 1: tan
692: 0: tan
693: .sp
694: Since the matching function does not support substring capture, the escape
695: sequences that are concerned with captured substrings are not relevant.
696: .
697: .
698: .SH "RESTARTING AFTER A PARTIAL MATCH"
699: .rs
700: .sp
701: When the alternative matching function has given the PCRE_ERROR_PARTIAL return,
702: indicating that the subject partially matched the pattern, you can restart the
703: match with additional subject data by means of the \eR escape sequence. For
704: example:
705: .sp
706: re> /^\ed?\ed(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\ed\ed$/
707: data> 23ja\eP\eD
708: Partial match: 23ja
709: data> n05\eR\eD
710: 0: n05
711: .sp
712: For further information about partial matching, see the
713: .\" HREF
714: \fBpcrepartial\fP
715: .\"
716: documentation.
717: .
718: .
719: .SH CALLOUTS
720: .rs
721: .sp
722: If the pattern contains any callout requests, \fBpcretest\fP's callout function
723: is called during matching. This works with both matching functions. By default,
724: the called function displays the callout number, the start and current
725: positions in the text at the callout time, and the next pattern item to be
726: tested. For example, the output
727: .sp
728: --->pqrabcdef
729: 0 ^ ^ \ed
730: .sp
731: indicates that callout number 0 occurred for a match attempt starting at the
732: fourth character of the subject string, when the pointer was at the seventh
733: character of the data, and when the next pattern item was \ed. Just one
734: circumflex is output if the start and current positions are the same.
735: .P
736: Callouts numbered 255 are assumed to be automatic callouts, inserted as a
737: result of the \fB/C\fP pattern modifier. In this case, instead of showing the
738: callout number, the offset in the pattern, preceded by a plus, is output. For
739: example:
740: .sp
741: re> /\ed?[A-E]\e*/C
742: data> E*
743: --->E*
744: +0 ^ \ed?
745: +3 ^ [A-E]
746: +8 ^^ \e*
747: +10 ^ ^
748: 0: E*
749: .sp
750: If a pattern contains (*MARK) items, an additional line is output whenever
751: a change of latest mark is passed to the callout function. For example:
752: .sp
753: re> /a(*MARK:X)bc/C
754: data> abc
755: --->abc
756: +0 ^ a
757: +1 ^^ (*MARK:X)
758: +10 ^^ b
759: Latest Mark: X
760: +11 ^ ^ c
761: +12 ^ ^
762: 0: abc
763: .sp
764: The mark changes between matching "a" and "b", but stays the same for the rest
765: of the match, so nothing more is output. If, as a result of backtracking, the
766: mark reverts to being unset, the text "<unset>" is output.
767: .P
768: The callout function in \fBpcretest\fP returns zero (carry on matching) by
769: default, but you can use a \eC item in a data line (as described above) to
770: change this and other parameters of the callout.
771: .P
772: Inserting callouts can be helpful when using \fBpcretest\fP to check
773: complicated regular expressions. For further information about callouts, see
774: the
775: .\" HREF
776: \fBpcrecallout\fP
777: .\"
778: documentation.
779: .
780: .
781: .
782: .SH "NON-PRINTING CHARACTERS"
783: .rs
784: .sp
785: When \fBpcretest\fP is outputting text in the compiled version of a pattern,
786: bytes other than 32-126 are always treated as non-printing characters are are
787: therefore shown as hex escapes.
788: .P
789: When \fBpcretest\fP is outputting text that is a matched part of a subject
790: string, it behaves in the same way, unless a different locale has been set for
791: the pattern (using the \fB/L\fP modifier). In this case, the \fBisprint()\fP
792: function to distinguish printing and non-printing characters.
793: .
794: .
795: .
796: .SH "SAVING AND RELOADING COMPILED PATTERNS"
797: .rs
798: .sp
799: The facilities described in this section are not available when the POSIX
800: interface to PCRE is being used, that is, when the \fB/P\fP pattern modifier is
801: specified.
802: .P
803: When the POSIX interface is not in use, you can cause \fBpcretest\fP to write a
804: compiled pattern to a file, by following the modifiers with > and a file name.
805: For example:
806: .sp
807: /pattern/im >/some/file
808: .sp
809: See the
810: .\" HREF
811: \fBpcreprecompile\fP
812: .\"
813: documentation for a discussion about saving and re-using compiled patterns.
814: Note that if the pattern was successfully studied with JIT optimization, the
815: JIT data cannot be saved.
816: .P
817: The data that is written is binary. The first eight bytes are the length of the
818: compiled pattern data followed by the length of the optional study data, each
819: written as four bytes in big-endian order (most significant byte first). If
820: there is no study data (either the pattern was not studied, or studying did not
821: return any data), the second length is zero. The lengths are followed by an
822: exact copy of the compiled pattern. If there is additional study data, this
823: (excluding any JIT data) follows immediately after the compiled pattern. After
824: writing the file, \fBpcretest\fP expects to read a new pattern.
825: .P
826: A saved pattern can be reloaded into \fBpcretest\fP by specifying < and a file
827: name instead of a pattern. The name of the file must not contain a < character,
828: as otherwise \fBpcretest\fP will interpret the line as a pattern delimited by <
829: characters.
830: For example:
831: .sp
832: re> </some/file
833: Compiled pattern loaded from /some/file
834: No study data
835: .sp
836: If the pattern was previously studied with the JIT optimization, the JIT
837: information cannot be saved and restored, and so is lost. When the pattern has
838: been loaded, \fBpcretest\fP proceeds to read data lines in the usual way.
839: .P
840: You can copy a file written by \fBpcretest\fP to a different host and reload it
841: there, even if the new host has opposite endianness to the one on which the
842: pattern was compiled. For example, you can compile on an i86 machine and run on
843: a SPARC machine.
844: .P
845: File names for saving and reloading can be absolute or relative, but note that
846: the shell facility of expanding a file name that starts with a tilde (~) is not
847: available.
848: .P
849: The ability to save and reload files in \fBpcretest\fP is intended for testing
850: and experimentation. It is not intended for production use because only a
851: single pattern can be written to a file. Furthermore, there is no facility for
852: supplying custom character tables for use with a reloaded pattern. If the
853: original pattern was compiled with custom tables, an attempt to match a subject
854: string using a reloaded pattern is likely to cause \fBpcretest\fP to crash.
855: Finally, if you attempt to load a file that is not in the correct format, the
856: result is undefined.
857: .
858: .
859: .SH "SEE ALSO"
860: .rs
861: .sp
862: \fBpcre\fP(3), \fBpcreapi\fP(3), \fBpcrecallout\fP(3), \fBpcrejit\fP,
863: \fBpcrematching\fP(3), \fBpcrepartial\fP(d), \fBpcrepattern\fP(3),
864: \fBpcreprecompile\fP(3).
865: .
866: .
867: .SH AUTHOR
868: .rs
869: .sp
870: .nf
871: Philip Hazel
872: University Computing Service
873: Cambridge CB2 3QH, England.
874: .fi
875: .
876: .
877: .SH REVISION
878: .rs
879: .sp
880: .nf
881: Last updated: 02 December 2011
882: Copyright (c) 1997-2011 University of Cambridge.
883: .fi
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