1PCRE2TEST(1) General Commands Manual PCRE2TEST(1)
2
6 pcre2test - a program for testing Perl-compatible regular expressions.
7
9 pcre2test [options] [input file [output file]]
11 pcre2test is a test program for the PCRE2 regular expression libraries,
13 but it can also be used for experimenting with regular expressions.
14 This document describes the features of the test program; for details
15 of the regular expressions themselves, see the pcre2pattern documenta‐
16 tion. For details of the PCRE2 library function calls and their
17 options, see the pcre2api documentation.
18 The input for pcre2test is a sequence of regular expression patterns
20 and subject strings to be matched. There are also command lines for
21 setting defaults and controlling some special actions. The output shows
22 the result of each match attempt. Modifiers on external or internal
23 command lines, the patterns, and the subject lines specify PCRE2 func‐
24 tion options, control how the subject is processed, and what output is
25 produced.
26 As the original fairly simple PCRE library evolved, it acquired many
28 different features, and as a result, the original pcretest program
29 ended up with a lot of options in a messy, arcane syntax for testing
30 all the features. The move to the new PCRE2 API provided an opportunity
31 to re-implement the test program as pcre2test, with a cleaner modifier
32 syntax. Nevertheless, there are still many obscure modifiers, some of
33 which are specifically designed for use in conjunction with the test
34 script and data files that are distributed as part of PCRE2. All the
35 modifiers are documented here, some without much justification, but
36 many of them are unlikely to be of use except when testing the
37 libraries.
38
40 Different versions of the PCRE2 library can be built to support charac‐
42 ter strings that are encoded in 8-bit, 16-bit, or 32-bit code units.
43 One, two, or all three of these libraries may be simultaneously
44 installed. The pcre2test program can be used to test all the libraries.
45 However, its own input and output are always in 8-bit format. When
46 testing the 16-bit or 32-bit libraries, patterns and subject strings
47 are converted to 16-bit or 32-bit format before being passed to the
48 library functions. Results are converted back to 8-bit code units for
49 output.
50 In the rest of this document, the names of library functions and struc‐
52 tures are given in generic form, for example, pcre_compile(). The
53 actual names used in the libraries have a suffix _8, _16, or _32, as
54 appropriate.
55
57 Input to pcre2test is processed line by line, either by calling the C
59 library's fgets() function, or via the libreadline library. In some
60 Windows environments character 26 (hex 1A) causes an immediate end of
61 file, and no further data is read, so this character should be avoided
62 unless you really want that action.
63 The input is processed using using C's string functions, so must not
65 contain binary zeroes, even though in Unix-like environments, fgets()
66 treats any bytes other than newline as data characters. An error is
67 generated if a binary zero is encountered. Subject lines are processed
68 for backslash escapes, which makes it possible to include any data
69 value in strings that are passed to the library for matching. For pat‐
70 terns, there is a facility for specifying some or all of the 8-bit
71 input characters as hexadecimal pairs, which makes it possible to
72 include binary zeros.
73 Input for the 16-bit and 32-bit libraries
75 When testing the 16-bit or 32-bit libraries, there is a need to be able
77 to generate character code points greater than 255 in the strings that
78 are passed to the library. For subject lines, backslash escapes can be
79 used. In addition, when the utf modifier (see "Setting compilation
80 options" below) is set, the pattern and any following subject lines are
81 interpreted as UTF-8 strings and translated to UTF-16 or UTF-32 as
82 appropriate.
83 For non-UTF testing of wide characters, the utf8_input modifier can be
85 used. This is mutually exclusive with utf, and is allowed only in
86 16-bit or 32-bit mode. It causes the pattern and following subject
87 lines to be treated as UTF-8 according to the original definition (RFC
88 2279), which allows for character values up to 0x7fffffff. Each charac‐
89 ter is placed in one 16-bit or 32-bit code unit (in the 16-bit case,
90 values greater than 0xffff cause an error to occur).
91 UTF-8 is not capable of encoding values greater than 0x7fffffff, but
93 such values can be handled by the 32-bit library. When testing this
94 library in non-UTF mode with utf8_input set, if any character is pre‐
95 ceded by the byte 0xff (which is an illegal byte in UTF-8) 0x80000000
96 is added to the character's value. This is the only way of passing such
97 code points in a pattern string. For subject strings, using an escape
98 sequence is preferable.
99
101 -8 If the 8-bit library has been built, this option causes it to
103 be used (this is the default). If the 8-bit library has not
104 been built, this option causes an error.
105 -16 If the 16-bit library has been built, this option causes it
107 to be used. If only the 16-bit library has been built, this
108 is the default. If the 16-bit library has not been built,
109 this option causes an error.
110 -32 If the 32-bit library has been built, this option causes it
112 to be used. If only the 32-bit library has been built, this
113 is the default. If the 32-bit library has not been built,
114 this option causes an error.
115 -ac Behave as if each pattern has the auto_callout modifier, that
117 is, insert automatic callouts into every pattern that is com‐
118 piled.
119 -b Behave as if each pattern has the fullbincode modifier; the
121 full internal binary form of the pattern is output after com‐
122 pilation.
123 -C Output the version number of the PCRE2 library, and all
125 available information about the optional features that are
126 included, and then exit with zero exit code. All other
127 options are ignored.
128 -C option Output information about a specific build-time option, then
130 exit. This functionality is intended for use in scripts such
131 as RunTest. The following options output the value and set
132 the exit code as indicated:
133 ebcdic-nl the code for LF (= NL) in an EBCDIC environment:
135 0x15 or 0x25
136 0 if used in an ASCII environment
137 exit code is always 0
138 linksize the configured internal link size (2, 3, or 4)
139 exit code is set to the link size
140 newline the default newline setting:
141 CR, LF, CRLF, ANYCRLF, or ANY
142 exit code is always 0
143 bsr the default setting for what \R matches:
144 ANYCRLF or ANY
145 exit code is always 0
146 The following options output 1 for true or 0 for false, and
148 set the exit code to the same value:
149 backslash-C \C is supported (not locked out)
151 ebcdic compiled for an EBCDIC environment
152 jit just-in-time support is available
153 pcre2-16 the 16-bit library was built
154 pcre2-32 the 32-bit library was built
155 pcre2-8 the 8-bit library was built
156 unicode Unicode support is available
157 If an unknown option is given, an error message is output;
159 the exit code is 0.
160 -d Behave as if each pattern has the debug modifier; the inter‐
162 nal form and information about the compiled pattern is output
163 after compilation; -d is equivalent to -b -i.
164 -dfa Behave as if each subject line has the dfa modifier; matching
166 is done using the pcre2_dfa_match() function instead of the
167 default pcre2_match().
168 -error number[,number,...]
170 Call pcre2_get_error_message() for each of the error numbers
171 in the comma-separated list, display the resulting messages
172 on the standard output, then exit with zero exit code. The
173 numbers may be positive or negative. This is a convenience
174 facility for PCRE2 maintainers.
175 -help Output a brief summary these options and then exit.
177 -i Behave as if each pattern has the info modifier; information
179 about the compiled pattern is given after compilation.
180 -jit Behave as if each pattern line has the jit modifier; after
182 successful compilation, each pattern is passed to the just-
183 in-time compiler, if available.
184 -pattern modifier-list
186 Behave as if each pattern line contains the given modifiers.
187 -q Do not output the version number of pcre2test at the start of
189 execution.
190 -S size On Unix-like systems, set the size of the run-time stack to
192 size megabytes.
193 -subject modifier-list
195 Behave as if each subject line contains the given modifiers.
196 -t Run each compile and match many times with a timer, and out‐
198 put the resulting times per compile or match. When JIT is
199 used, separate times are given for the initial compile and
200 the JIT compile. You can control the number of iterations
201 that are used for timing by following -t with a number (as a
202 separate item on the command line). For example, "-t 1000"
203 iterates 1000 times. The default is to iterate 500,000 times.
204 -tm This is like -t except that it times only the matching phase,
206 not the compile phase.
207 -T -TM These behave like -t and -tm, but in addition, at the end of
209 a run, the total times for all compiles and matches are out‐
210 put.
211 -version Output the PCRE2 version number and then exit.
213
215 If pcre2test is given two filename arguments, it reads from the first
217 and writes to the second. If the first name is "-", input is taken from
218 the standard input. If pcre2test is given only one argument, it reads
219 from that file and writes to stdout. Otherwise, it reads from stdin and
220 writes to stdout.
221 When pcre2test is built, a configuration option can specify that it
223 should be linked with the libreadline or libedit library. When this is
224 done, if the input is from a terminal, it is read using the readline()
225 function. This provides line-editing and history facilities. The output
226 from the -help option states whether or not readline() will be used.
227 The program handles any number of tests, each of which consists of a
229 set of input lines. Each set starts with a regular expression pattern,
230 followed by any number of subject lines to be matched against that pat‐
231 tern. In between sets of test data, command lines that begin with # may
232 appear. This file format, with some restrictions, can also be processed
233 by the perltest.sh script that is distributed with PCRE2 as a means of
234 checking that the behaviour of PCRE2 and Perl is the same.
235 When the input is a terminal, pcre2test prompts for each line of input,
237 using "re>" to prompt for regular expression patterns, and "data>" to
238 prompt for subject lines. Command lines starting with # can be entered
239 only in response to the "re>" prompt.
240 Each subject line is matched separately and independently. If you want
242 to do multi-line matches, you have to use the \n escape sequence (or \r
243 or \r\n, etc., depending on the newline setting) in a single line of
244 input to encode the newline sequences. There is no limit on the length
245 of subject lines; the input buffer is automatically extended if it is
246 too small. There are replication features that makes it possible to
247 generate long repetitive pattern or subject lines without having to
248 supply them explicitly.
249 An empty line or the end of the file signals the end of the subject
251 lines for a test, at which point a new pattern or command line is
252 expected if there is still input to be read.
253
255 In between sets of test data, a line that begins with # is interpreted
257 as a command line. If the first character is followed by white space or
258 an exclamation mark, the line is treated as a comment, and ignored.
259 Otherwise, the following commands are recognized:
260 #forbid_utf
262 Subsequent patterns automatically have the PCRE2_NEVER_UTF and
264 PCRE2_NEVER_UCP options set, which locks out the use of the PCRE2_UTF
265 and PCRE2_UCP options and the use of (*UTF) and (*UCP) at the start of
266 patterns. This command also forces an error if a subsequent pattern
267 contains any occurrences of \P, \p, or \X, which are still supported
268 when PCRE2_UTF is not set, but which require Unicode property support
269 to be included in the library.
270 This is a trigger guard that is used in test files to ensure that UTF
272 or Unicode property tests are not accidentally added to files that are
273 used when Unicode support is not included in the library. Setting
274 PCRE2_NEVER_UTF and PCRE2_NEVER_UCP as a default can also be obtained
275 by the use of #pattern; the difference is that #forbid_utf cannot be
276 unset, and the automatic options are not displayed in pattern informa‐
277 tion, to avoid cluttering up test output.
278 #load <filename>
280 This command is used to load a set of precompiled patterns from a file,
282 as described in the section entitled "Saving and restoring compiled
283 patterns" below.
284 #newline_default [<newline-list>]
286 When PCRE2 is built, a default newline convention can be specified.
288 This determines which characters and/or character pairs are recognized
289 as indicating a newline in a pattern or subject string. The default can
290 be overridden when a pattern is compiled. The standard test files con‐
291 tain tests of various newline conventions, but the majority of the
292 tests expect a single linefeed to be recognized as a newline by
293 default. Without special action the tests would fail when PCRE2 is com‐
294 piled with either CR or CRLF as the default newline.
295 The #newline_default command specifies a list of newline types that are
297 acceptable as the default. The types must be one of CR, LF, CRLF, ANY‐
298 CRLF, or ANY (in upper or lower case), for example:
299 #newline_default LF Any anyCRLF
301 If the default newline is in the list, this command has no effect. Oth‐
303 erwise, except when testing the POSIX API, a newline modifier that
304 specifies the first newline convention in the list (LF in the above
305 example) is added to any pattern that does not already have a newline
306 modifier. If the newline list is empty, the feature is turned off. This
307 command is present in a number of the standard test input files.
308 When the POSIX API is being tested there is no way to override the
310 default newline convention, though it is possible to set the newline
311 convention from within the pattern. A warning is given if the posix
312 modifier is used when #newline_default would set a default for the non-
313 POSIX API.
314 #pattern <modifier-list>
316 This command sets a default modifier list that applies to all subse‐
318 quent patterns. Modifiers on a pattern can change these settings.
319 #perltest
321 The appearance of this line causes all subsequent modifier settings to
323 be checked for compatibility with the perltest.sh script, which is used
324 to confirm that Perl gives the same results as PCRE2. Also, apart from
325 comment lines, none of the other command lines are permitted, because
326 they and many of the modifiers are specific to pcre2test, and should
327 not be used in test files that are also processed by perltest.sh. The
328 #perltest command helps detect tests that are accidentally put in the
329 wrong file.
330 #pop [<modifiers>]
332 #popcopy [<modifiers>]
333 These commands are used to manipulate the stack of compiled patterns,
335 as described in the section entitled "Saving and restoring compiled
336 patterns" below.
337 #save <filename>
339 This command is used to save a set of compiled patterns to a file, as
341 described in the section entitled "Saving and restoring compiled pat‐
342 terns" below.
343 #subject <modifier-list>
345 This command sets a default modifier list that applies to all subse‐
347 quent subject lines. Modifiers on a subject line can change these set‐
348 tings.
349
351 Modifier lists are used with both pattern and subject lines. Items in a
353 list are separated by commas followed by optional white space. Trailing
354 whitespace in a modifier list is ignored. Some modifiers may be given
355 for both patterns and subject lines, whereas others are valid only for
356 one or the other. Each modifier has a long name, for example
357 "anchored", and some of them must be followed by an equals sign and a
358 value, for example, "offset=12". Values cannot contain comma charac‐
359 ters, but may contain spaces. Modifiers that do not take values may be
360 preceded by a minus sign to turn off a previous setting.
361 A few of the more common modifiers can also be specified as single let‐
363 ters, for example "i" for "caseless". In documentation, following the
364 Perl convention, these are written with a slash ("the /i modifier") for
365 clarity. Abbreviated modifiers must all be concatenated in the first
366 item of a modifier list. If the first item is not recognized as a long
367 modifier name, it is interpreted as a sequence of these abbreviations.
368 For example:
369 /abc/ig,newline=cr,jit=3
371 This is a pattern line whose modifier list starts with two one-letter
373 modifiers (/i and /g). The lower-case abbreviated modifiers are the
374 same as used in Perl.
375
377 A pattern line must start with one of the following characters (common
379 symbols, excluding pattern meta-characters):
380 / ! " ' ` - = _ : ; , % & @ ~
382 This is interpreted as the pattern's delimiter. A regular expression
384 may be continued over several input lines, in which case the newline
385 characters are included within it. It is possible to include the delim‐
386 iter within the pattern by escaping it with a backslash, for example
387 /abc\/def/
389 If you do this, the escape and the delimiter form part of the pattern,
391 but since the delimiters are all non-alphanumeric, this does not affect
392 its interpretation. If the terminating delimiter is immediately fol‐
393 lowed by a backslash, for example,
394 /abc/\
396 then a backslash is added to the end of the pattern. This is done to
398 provide a way of testing the error condition that arises if a pattern
399 finishes with a backslash, because
400 /abc\/
402 is interpreted as the first line of a pattern that starts with "abc/",
404 causing pcre2test to read the next line as a continuation of the regu‐
405 lar expression.
406 A pattern can be followed by a modifier list (details below).
408
410 Before each subject line is passed to pcre2_match() or
412 pcre2_dfa_match(), leading and trailing white space is removed, and the
413 line is scanned for backslash escapes. The following provide a means of
414 encoding non-printing characters in a visible way:
415 \a alarm (BEL, \x07)
417 \b backspace (\x08)
418 \e escape (\x27)
419 \f form feed (\x0c)
420 \n newline (\x0a)
421 \r carriage return (\x0d)
422 \t tab (\x09)
423 \v vertical tab (\x0b)
424 \nnn octal character (up to 3 octal digits); always
425 a byte unless > 255 in UTF-8 or 16-bit or 32-bit mode
426 \o{dd...} octal character (any number of octal digits}
427 \xhh hexadecimal byte (up to 2 hex digits)
428 \x{hh...} hexadecimal character (any number of hex digits)
429 The use of \x{hh...} is not dependent on the use of the utf modifier on
431 the pattern. It is recognized always. There may be any number of hexa‐
432 decimal digits inside the braces; invalid values provoke error mes‐
433 sages.
434 Note that \xhh specifies one byte rather than one character in UTF-8
436 mode; this makes it possible to construct invalid UTF-8 sequences for
437 testing purposes. On the other hand, \x{hh} is interpreted as a UTF-8
438 character in UTF-8 mode, generating more than one byte if the value is
439 greater than 127. When testing the 8-bit library not in UTF-8 mode,
440 \x{hh} generates one byte for values less than 256, and causes an error
441 for greater values.
442 In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
444 possible to construct invalid UTF-16 sequences for testing purposes.
445 In UTF-32 mode, all 4- to 8-digit \x{...} values are accepted. This
447 makes it possible to construct invalid UTF-32 sequences for testing
448 purposes.
449 There is a special backslash sequence that specifies replication of one
451 or more characters:
452 \[<characters>]{<count>}
454 This makes it possible to test long strings without having to provide
456 them as part of the file. For example:
457 \[abc]{4}
459 is converted to "abcabcabcabc". This feature does not support nesting.
461 To include a closing square bracket in the characters, code it as \x5D.
462 A backslash followed by an equals sign marks the end of the subject
464 string and the start of a modifier list. For example:
465 abc\=notbol,notempty
467 If the subject string is empty and \= is followed by whitespace, the
469 line is treated as a comment line, and is not used for matching. For
470 example:
471 \= This is a comment.
473 abc\= This is an invalid modifier list.
474 A backslash followed by any other non-alphanumeric character just
476 escapes that character. A backslash followed by anything else causes an
477 error. However, if the very last character in the line is a backslash
478 (and there is no modifier list), it is ignored. This gives a way of
479 passing an empty line as data, since a real empty line terminates the
480 data input.
481
483 There are several types of modifier that can appear in pattern lines.
485 Except where noted below, they may also be used in #pattern commands. A
486 pattern's modifier list can add to or override default modifiers that
487 were set by a previous #pattern command.
488 Setting compilation options
490 The following modifiers set options for pcre2_compile(). The most com‐
492 mon ones have single-letter abbreviations. See pcre2api for a descrip‐
493 tion of their effects.
494 allow_empty_class set PCRE2_ALLOW_EMPTY_CLASS
496 alt_bsux set PCRE2_ALT_BSUX
497 alt_circumflex set PCRE2_ALT_CIRCUMFLEX
498 alt_verbnames set PCRE2_ALT_VERBNAMES
499 anchored set PCRE2_ANCHORED
500 auto_callout set PCRE2_AUTO_CALLOUT
501 /i caseless set PCRE2_CASELESS
502 dollar_endonly set PCRE2_DOLLAR_ENDONLY
503 /s dotall set PCRE2_DOTALL
504 dupnames set PCRE2_DUPNAMES
505 /x extended set PCRE2_EXTENDED
506 firstline set PCRE2_FIRSTLINE
507 match_unset_backref set PCRE2_MATCH_UNSET_BACKREF
508 /m multiline set PCRE2_MULTILINE
509 never_backslash_c set PCRE2_NEVER_BACKSLASH_C
510 never_ucp set PCRE2_NEVER_UCP
511 never_utf set PCRE2_NEVER_UTF
512 no_auto_capture set PCRE2_NO_AUTO_CAPTURE
513 no_auto_possess set PCRE2_NO_AUTO_POSSESS
514 no_dotstar_anchor set PCRE2_NO_DOTSTAR_ANCHOR
515 no_start_optimize set PCRE2_NO_START_OPTIMIZE
516 no_utf_check set PCRE2_NO_UTF_CHECK
517 ucp set PCRE2_UCP
518 ungreedy set PCRE2_UNGREEDY
519 use_offset_limit set PCRE2_USE_OFFSET_LIMIT
520 utf set PCRE2_UTF
521 As well as turning on the PCRE2_UTF option, the utf modifier causes all
523 non-printing characters in output strings to be printed using the
524 \x{hh...} notation. Otherwise, those less than 0x100 are output in hex
525 without the curly brackets. Setting utf in 16-bit or 32-bit mode also
526 causes pattern and subject strings to be translated to UTF-16 or
527 UTF-32, respectively, before being passed to library functions.
528 Setting compilation controls
530 The following modifiers affect the compilation process or request
532 information about the pattern:
533 bsr=[anycrlf|unicode] specify \R handling
535 /B bincode show binary code without lengths
536 callout_info show callout information
537 debug same as info,fullbincode
538 fullbincode show binary code with lengths
539 /I info show info about compiled pattern
540 hex unquoted characters are hexadecimal
541 jit[=<number>] use JIT
542 jitfast use JIT fast path
543 jitverify verify JIT use
544 locale=<name> use this locale
545 max_pattern_length=<n> set the maximum pattern length
546 memory show memory used
547 newline=<type> set newline type
548 null_context compile with a NULL context
549 parens_nest_limit=<n> set maximum parentheses depth
550 posix use the POSIX API
551 posix_nosub use the POSIX API with REG_NOSUB
552 push push compiled pattern onto the stack
553 pushcopy push a copy onto the stack
554 stackguard=<number> test the stackguard feature
555 tables=[0|1|2] select internal tables
556 use_length do not zero-terminate the pattern
557 utf8_input treat input as UTF-8
558 The effects of these modifiers are described in the following sections.
560 Newline and \R handling
562 The bsr modifier specifies what \R in a pattern should match. If it is
564 set to "anycrlf", \R matches CR, LF, or CRLF only. If it is set to
565 "unicode", \R matches any Unicode newline sequence. The default is
566 specified when PCRE2 is built, with the default default being Unicode.
567 The newline modifier specifies which characters are to be interpreted
569 as newlines, both in the pattern and in subject lines. The type must be
570 one of CR, LF, CRLF, ANYCRLF, or ANY (in upper or lower case).
571 Information about a pattern
573 The debug modifier is a shorthand for info,fullbincode, requesting all
575 available information.
576 The bincode modifier causes a representation of the compiled code to be
578 output after compilation. This information does not contain length and
579 offset values, which ensures that the same output is generated for dif‐
580 ferent internal link sizes and different code unit widths. By using
581 bincode, the same regression tests can be used in different environ‐
582 ments.
583 The fullbincode modifier, by contrast, does include length and offset
585 values. This is used in a few special tests that run only for specific
586 code unit widths and link sizes, and is also useful for one-off tests.
587 The info modifier requests information about the compiled pattern
589 (whether it is anchored, has a fixed first character, and so on). The
590 information is obtained from the pcre2_pattern_info() function. Here
591 are some typical examples:
592 re> /(?i)(^a|^b)/m,info
594 Capturing subpattern count = 1
595 Compile options: multiline
596 Overall options: caseless multiline
597 First code unit at start or follows newline
598 Subject length lower bound = 1
599 re> /(?i)abc/info
601 Capturing subpattern count = 0
602 Compile options: <none>
603 Overall options: caseless
604 First code unit = 'a' (caseless)
605 Last code unit = 'c' (caseless)
606 Subject length lower bound = 3
607 "Compile options" are those specified by modifiers; "overall options"
609 have added options that are taken or deduced from the pattern. If both
610 sets of options are the same, just a single "options" line is output;
611 if there are no options, the line is omitted. "First code unit" is
612 where any match must start; if there is more than one they are listed
613 as "starting code units". "Last code unit" is the last literal code
614 unit that must be present in any match. This is not necessarily the
615 last character. These lines are omitted if no starting or ending code
616 units are recorded.
617 The callout_info modifier requests information about all the callouts
619 in the pattern. A list of them is output at the end of any other infor‐
620 mation that is requested. For each callout, either its number or string
621 is given, followed by the item that follows it in the pattern.
622 Passing a NULL context
624 Normally, pcre2test passes a context block to pcre2_compile(). If the
626 null_context modifier is set, however, NULL is passed. This is for
627 testing that pcre2_compile() behaves correctly in this case (it uses
628 default values).
629 Specifying the pattern's length
631 By default, patterns are passed to the compiling functions as zero-ter‐
633 minated strings. When using the POSIX wrapper API, there is no other
634 option. However, when using PCRE2's native API, patterns can be passed
635 by length instead of being zero-terminated. The use_length modifier
636 causes this to happen. Using a length happens automatically (whether
637 or not use_length is set) when hex is set, because patterns specified
638 in hexadecimal may contain binary zeros.
639 Specifying pattern characters in hexadecimal
641 The hex modifier specifies that the characters of the pattern, except
643 for substrings enclosed in single or double quotes, are to be inter‐
644 preted as pairs of hexadecimal digits. This feature is provided as a
645 way of creating patterns that contain binary zeros and other non-print‐
646 ing characters. White space is permitted between pairs of digits. For
647 example, this pattern contains three characters:
648 /ab 32 59/hex
650 Parts of such a pattern are taken literally if quoted. This pattern
652 contains nine characters, only two of which are specified in hexadeci‐
653 mal:
654 /ab "literal" 32/hex
656 Either single or double quotes may be used. There is no way of includ‐
658 ing the delimiter within a substring. The hex and expand modifiers are
659 mutually exclusive.
660 The POSIX API cannot be used with patterns specified in hexadecimal
662 because they may contain binary zeros, which conflicts with regcomp()'s
663 requirement for a zero-terminated string. Such patterns are always
664 passed to pcre2_compile() as a string with a length, not as zero-termi‐
665 nated.
666 Specifying wide characters in 16-bit and 32-bit modes
668 In 16-bit and 32-bit modes, all input is automatically treated as UTF-8
670 and translated to UTF-16 or UTF-32 when the utf modifier is set. For
671 testing the 16-bit and 32-bit libraries in non-UTF mode, the utf8_input
672 modifier can be used. It is mutually exclusive with utf. Input lines
673 are interpreted as UTF-8 as a means of specifying wide characters. More
674 details are given in "Input encoding" above.
675 Generating long repetitive patterns
677 Some tests use long patterns that are very repetitive. Instead of cre‐
679 ating a very long input line for such a pattern, you can use a special
680 repetition feature, similar to the one described for subject lines
681 above. If the expand modifier is present on a pattern, parts of the
682 pattern that have the form
683 \[<characters>]{<count>}
685 are expanded before the pattern is passed to pcre2_compile(). For exam‐
687 ple, \[AB]{6000} is expanded to "ABAB..." 6000 times. This construction
688 cannot be nested. An initial "\[" sequence is recognized only if "]{"
689 followed by decimal digits and "}" is found later in the pattern. If
690 not, the characters remain in the pattern unaltered. The expand and hex
691 modifiers are mutually exclusive.
692 If part of an expanded pattern looks like an expansion, but is really
694 part of the actual pattern, unwanted expansion can be avoided by giving
695 two values in the quantifier. For example, \[AB]{6000,6000} is not rec‐
696 ognized as an expansion item.
697 If the info modifier is set on an expanded pattern, the result of the
699 expansion is included in the information that is output.
700 JIT compilation
702 Just-in-time (JIT) compiling is a heavyweight optimization that can
704 greatly speed up pattern matching. See the pcre2jit documentation for
705 details. JIT compiling happens, optionally, after a pattern has been
706 successfully compiled into an internal form. The JIT compiler converts
707 this to optimized machine code. It needs to know whether the match-time
708 options PCRE2_PARTIAL_HARD and PCRE2_PARTIAL_SOFT are going to be used,
709 because different code is generated for the different cases. See the
710 partial modifier in "Subject Modifiers" below for details of how these
711 options are specified for each match attempt.
712 JIT compilation is requested by the /jit pattern modifier, which may
714 optionally be followed by an equals sign and a number in the range 0 to
715 7. The three bits that make up the number specify which of the three
716 JIT operating modes are to be compiled:
717 1 compile JIT code for non-partial matching
719 2 compile JIT code for soft partial matching
720 4 compile JIT code for hard partial matching
721 The possible values for the jit modifier are therefore:
723 0 disable JIT
725 1 normal matching only
726 2 soft partial matching only
727 3 normal and soft partial matching
728 4 hard partial matching only
729 6 soft and hard partial matching only
730 7 all three modes
731 If no number is given, 7 is assumed. The phrase "partial matching"
733 means a call to pcre2_match() with either the PCRE2_PARTIAL_SOFT or the
734 PCRE2_PARTIAL_HARD option set. Note that such a call may return a com‐
735 plete match; the options enable the possibility of a partial match, but
736 do not require it. Note also that if you request JIT compilation only
737 for partial matching (for example, /jit=2) but do not set the partial
738 modifier on a subject line, that match will not use JIT code because
739 none was compiled for non-partial matching.
740 If JIT compilation is successful, the compiled JIT code will automati‐
742 cally be used when an appropriate type of match is run, except when
743 incompatible run-time options are specified. For more details, see the
744 pcre2jit documentation. See also the jitstack modifier below for a way
745 of setting the size of the JIT stack.
746 If the jitfast modifier is specified, matching is done using the JIT
748 "fast path" interface, pcre2_jit_match(), which skips some of the san‐
749 ity checks that are done by pcre2_match(), and of course does not work
750 when JIT is not supported. If jitfast is specified without jit, jit=7
751 is assumed.
752 If the jitverify modifier is specified, information about the compiled
754 pattern shows whether JIT compilation was or was not successful. If
755 jitverify is specified without jit, jit=7 is assumed. If JIT compila‐
756 tion is successful when jitverify is set, the text "(JIT)" is added to
757 the first output line after a match or non match when JIT-compiled code
758 was actually used in the match.
759 Setting a locale
761 The locale modifier must specify the name of a locale, for example:
763 /pattern/locale=fr_FR
765 The given locale is set, pcre2_maketables() is called to build a set of
767 character tables for the locale, and this is then passed to pcre2_com‐
768 pile() when compiling the regular expression. The same tables are used
769 when matching the following subject lines. The locale modifier applies
770 only to the pattern on which it appears, but can be given in a #pattern
771 command if a default is needed. Setting a locale and alternate charac‐
772 ter tables are mutually exclusive.
773 Showing pattern memory
775 The memory modifier causes the size in bytes of the memory used to hold
777 the compiled pattern to be output. This does not include the size of
778 the pcre2_code block; it is just the actual compiled data. If the pat‐
779 tern is subsequently passed to the JIT compiler, the size of the JIT
780 compiled code is also output. Here is an example:
781 re> /a(b)c/jit,memory
783 Memory allocation (code space): 21
784 Memory allocation (JIT code): 1910
785 Limiting nested parentheses
788 The parens_nest_limit modifier sets a limit on the depth of nested
790 parentheses in a pattern. Breaching the limit causes a compilation
791 error. The default for the library is set when PCRE2 is built, but
792 pcre2test sets its own default of 220, which is required for running
793 the standard test suite.
794 Limiting the pattern length
796 The max_pattern_length modifier sets a limit, in code units, to the
798 length of pattern that pcre2_compile() will accept. Breaching the limit
799 causes a compilation error. The default is the largest number a
800 PCRE2_SIZE variable can hold (essentially unlimited).
801 Using the POSIX wrapper API
803 The /posix and posix_nosub modifiers cause pcre2test to call PCRE2 via
805 the POSIX wrapper API rather than its native API. When posix_nosub is
806 used, the POSIX option REG_NOSUB is passed to regcomp(). The POSIX
807 wrapper supports only the 8-bit library. Note that it does not imply
808 POSIX matching semantics; for more detail see the pcre2posix documenta‐
809 tion. The following pattern modifiers set options for the regcomp()
810 function:
811 caseless REG_ICASE
813 multiline REG_NEWLINE
814 dotall REG_DOTALL )
815 ungreedy REG_UNGREEDY ) These options are not part of
816 ucp REG_UCP ) the POSIX standard
817 utf REG_UTF8 )
818 The regerror_buffsize modifier specifies a size for the error buffer
820 that is passed to regerror() in the event of a compilation error. For
821 example:
822 /abc/posix,regerror_buffsize=20
824 This provides a means of testing the behaviour of regerror() when the
826 buffer is too small for the error message. If this modifier has not
827 been set, a large buffer is used.
828 The aftertext and allaftertext subject modifiers work as described
830 below. All other modifiers are either ignored, with a warning message,
831 or cause an error.
832 Testing the stack guard feature
834 The stackguard modifier is used to test the use of pcre2_set_com‐
836 pile_recursion_guard(), a function that is provided to enable stack
837 availability to be checked during compilation (see the pcre2api docu‐
838 mentation for details). If the number specified by the modifier is
839 greater than zero, pcre2_set_compile_recursion_guard() is called to set
840 up callback from pcre2_compile() to a local function. The argument it
841 receives is the current nesting parenthesis depth; if this is greater
842 than the value given by the modifier, non-zero is returned, causing the
843 compilation to be aborted.
844 Using alternative character tables
846 The value specified for the tables modifier must be one of the digits
848 0, 1, or 2. It causes a specific set of built-in character tables to be
849 passed to pcre2_compile(). This is used in the PCRE2 tests to check be‐
850 haviour with different character tables. The digit specifies the tables
851 as follows:
852 0 do not pass any special character tables
854 1 the default ASCII tables, as distributed in
855 pcre2_chartables.c.dist
856 2 a set of tables defining ISO 8859 characters
857 In table 2, some characters whose codes are greater than 128 are iden‐
859 tified as letters, digits, spaces, etc. Setting alternate character
860 tables and a locale are mutually exclusive.
861 Setting certain match controls
863 The following modifiers are really subject modifiers, and are described
865 below. However, they may be included in a pattern's modifier list, in
866 which case they are applied to every subject line that is processed
867 with that pattern. They may not appear in #pattern commands. These mod‐
868 ifiers do not affect the compilation process.
869 aftertext show text after match
871 allaftertext show text after captures
872 allcaptures show all captures
873 allusedtext show all consulted text
874 /g global global matching
875 mark show mark values
876 replace=<string> specify a replacement string
877 startchar show starting character when relevant
878 substitute_extended use PCRE2_SUBSTITUTE_EXTENDED
879 substitute_overflow_length use PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
880 substitute_unknown_unset use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
881 substitute_unset_empty use PCRE2_SUBSTITUTE_UNSET_EMPTY
882 These modifiers may not appear in a #pattern command. If you want them
884 as defaults, set them in a #subject command.
885 Saving a compiled pattern
887 When a pattern with the push modifier is successfully compiled, it is
889 pushed onto a stack of compiled patterns, and pcre2test expects the
890 next line to contain a new pattern (or a command) instead of a subject
891 line. This facility is used when saving compiled patterns to a file, as
892 described in the section entitled "Saving and restoring compiled pat‐
893 terns" below. If pushcopy is used instead of push, a copy of the com‐
894 piled pattern is stacked, leaving the original as current, ready to
895 match the following input lines. This provides a way of testing the
896 pcre2_code_copy() function. The push and pushcopy modifiers are
897 incompatible with compilation modifiers such as global that act at
898 match time. Any that are specified are ignored (for the stacked copy),
899 with a warning message, except for replace, which causes an error. Note
900 that jitverify, which is allowed, does not carry through to any subse‐
901 quent matching that uses a stacked pattern.
902
904 The modifiers that can appear in subject lines and the #subject command
906 are of two types.
907 Setting match options
909 The following modifiers set options for pcre2_match() or
911 pcre2_dfa_match(). See pcreapi for a description of their effects.
912 anchored set PCRE2_ANCHORED
914 dfa_restart set PCRE2_DFA_RESTART
915 dfa_shortest set PCRE2_DFA_SHORTEST
916 no_jit set PCRE2_NO_JIT
917 no_utf_check set PCRE2_NO_UTF_CHECK
918 notbol set PCRE2_NOTBOL
919 notempty set PCRE2_NOTEMPTY
920 notempty_atstart set PCRE2_NOTEMPTY_ATSTART
921 noteol set PCRE2_NOTEOL
922 partial_hard (or ph) set PCRE2_PARTIAL_HARD
923 partial_soft (or ps) set PCRE2_PARTIAL_SOFT
924 The partial matching modifiers are provided with abbreviations because
926 they appear frequently in tests.
927 If the posix modifier was present on the pattern, causing the POSIX
929 wrapper API to be used, the only option-setting modifiers that have any
930 effect are notbol, notempty, and noteol, causing REG_NOTBOL,
931 REG_NOTEMPTY, and REG_NOTEOL, respectively, to be passed to regexec().
932 The other modifiers are ignored, with a warning message.
933 Setting match controls
935 The following modifiers affect the matching process or request addi‐
937 tional information. Some of them may also be specified on a pattern
938 line (see above), in which case they apply to every subject line that
939 is matched against that pattern.
940 aftertext show text after match
942 allaftertext show text after captures
943 allcaptures show all captures
944 allusedtext show all consulted text (non-JIT only)
945 altglobal alternative global matching
946 callout_capture show captures at callout time
947 callout_data=<n> set a value to pass via callouts
948 callout_error=<n>[:<m>] control callout error
949 callout_fail=<n>[:<m>] control callout failure
950 callout_none do not supply a callout function
951 copy=<number or name> copy captured substring
952 dfa use pcre2_dfa_match()
953 find_limits find match and recursion limits
954 get=<number or name> extract captured substring
955 getall extract all captured substrings
956 /g global global matching
957 jitstack=<n> set size of JIT stack
958 mark show mark values
959 match_limit=<n> set a match limit
960 memory show memory usage
961 null_context match with a NULL context
962 offset=<n> set starting offset
963 offset_limit=<n> set offset limit
964 ovector=<n> set size of output vector
965 recursion_limit=<n> set a recursion limit
966 replace=<string> specify a replacement string
967 startchar show startchar when relevant
968 startoffset=<n> same as offset=<n>
969 substitute_extedded use PCRE2_SUBSTITUTE_EXTENDED
970 substitute_overflow_length use PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
971 substitute_unknown_unset use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
972 substitute_unset_empty use PCRE2_SUBSTITUTE_UNSET_EMPTY
973 zero_terminate pass the subject as zero-terminated
974 The effects of these modifiers are described in the following sections.
976 When matching via the POSIX wrapper API, the aftertext, allaftertext,
977 and ovector subject modifiers work as described below. All other modi‐
978 fiers are either ignored, with a warning message, or cause an error.
979 Showing more text
981 The aftertext modifier requests that as well as outputting the part of
983 the subject string that matched the entire pattern, pcre2test should in
984 addition output the remainder of the subject string. This is useful for
985 tests where the subject contains multiple copies of the same substring.
986 The allaftertext modifier requests the same action for captured sub‐
987 strings as well as the main matched substring. In each case the remain‐
988 der is output on the following line with a plus character following the
989 capture number.
990 The allusedtext modifier requests that all the text that was consulted
992 during a successful pattern match by the interpreter should be shown.
993 This feature is not supported for JIT matching, and if requested with
994 JIT it is ignored (with a warning message). Setting this modifier
995 affects the output if there is a lookbehind at the start of a match, or
996 a lookahead at the end, or if \K is used in the pattern. Characters
997 that precede or follow the start and end of the actual match are indi‐
998 cated in the output by '<' or '>' characters underneath them. Here is
999 an example:
1000 re> /(?<=pqr)abc(?=xyz)/
1002 data> 123pqrabcxyz456\=allusedtext
1003 0: pqrabcxyz
1004 <<< >>>
1005 This shows that the matched string is "abc", with the preceding and
1007 following strings "pqr" and "xyz" having been consulted during the
1008 match (when processing the assertions).
1009 The startchar modifier requests that the starting character for the
1011 match be indicated, if it is different to the start of the matched
1012 string. The only time when this occurs is when \K has been processed as
1013 part of the match. In this situation, the output for the matched string
1014 is displayed from the starting character instead of from the match
1015 point, with circumflex characters under the earlier characters. For
1016 example:
1017 re> /abc\Kxyz/
1019 data> abcxyz\=startchar
1020 0: abcxyz
1021 ^^^
1022 Unlike allusedtext, the startchar modifier can be used with JIT. How‐
1024 ever, these two modifiers are mutually exclusive.
1025 Showing the value of all capture groups
1027 The allcaptures modifier requests that the values of all potential cap‐
1029 tured parentheses be output after a match. By default, only those up to
1030 the highest one actually used in the match are output (corresponding to
1031 the return code from pcre2_match()). Groups that did not take part in
1032 the match are output as "<unset>". This modifier is not relevant for
1033 DFA matching (which does no capturing); it is ignored, with a warning
1034 message, if present.
1035 Testing callouts
1037 A callout function is supplied when pcre2test calls the library match‐
1039 ing functions, unless callout_none is specified. If callout_capture is
1040 set, the current captured groups are output when a callout occurs. The
1041 default return from the callout function is zero, which allows matching
1042 to continue.
1043 The callout_fail modifier can be given one or two numbers. If there is
1045 only one number, 1 is returned instead of 0 (causing matching to back‐
1046 track) when a callout of that number is reached. If two numbers
1047 (<n>:<m>) are given, 1 is returned when callout <n> is reached and
1048 there have been at least <m> callouts. The callout_error modifier is
1049 similar, except that PCRE2_ERROR_CALLOUT is returned, causing the
1050 entire matching process to be aborted. If both these modifiers are set
1051 for the same callout number, callout_error takes precedence.
1052 Note that callouts with string arguments are always given the number
1054 zero. See "Callouts" below for a description of the output when a call‐
1055 out it taken.
1056 The callout_data modifier can be given an unsigned or a negative num‐
1058 ber. This is set as the "user data" that is passed to the matching
1059 function, and passed back when the callout function is invoked. Any
1060 value other than zero is used as a return from pcre2test's callout
1061 function.
1062 Finding all matches in a string
1064 Searching for all possible matches within a subject can be requested by
1066 the global or altglobal modifier. After finding a match, the matching
1067 function is called again to search the remainder of the subject. The
1068 difference between global and altglobal is that the former uses the
1069 start_offset argument to pcre2_match() or pcre2_dfa_match() to start
1070 searching at a new point within the entire string (which is what Perl
1071 does), whereas the latter passes over a shortened subject. This makes a
1072 difference to the matching process if the pattern begins with a lookbe‐
1073 hind assertion (including \b or \B).
1074 If an empty string is matched, the next match is done with the
1076 PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED flags set, in order to search
1077 for another, non-empty, match at the same point in the subject. If this
1078 match fails, the start offset is advanced, and the normal match is
1079 retried. This imitates the way Perl handles such cases when using the
1080 /g modifier or the split() function. Normally, the start offset is
1081 advanced by one character, but if the newline convention recognizes
1082 CRLF as a newline, and the current character is CR followed by LF, an
1083 advance of two characters occurs.
1084 Testing substring extraction functions
1086 The copy and get modifiers can be used to test the pcre2_sub‐
1088 string_copy_xxx() and pcre2_substring_get_xxx() functions. They can be
1089 given more than once, and each can specify a group name or number, for
1090 example:
1091 abcd\=copy=1,copy=3,get=G1
1093 If the #subject command is used to set default copy and/or get lists,
1095 these can be unset by specifying a negative number to cancel all num‐
1096 bered groups and an empty name to cancel all named groups.
1097 The getall modifier tests pcre2_substring_list_get(), which extracts
1099 all captured substrings.
1100 If the subject line is successfully matched, the substrings extracted
1102 by the convenience functions are output with C, G, or L after the
1103 string number instead of a colon. This is in addition to the normal
1104 full list. The string length (that is, the return from the extraction
1105 function) is given in parentheses after each substring, followed by the
1106 name when the extraction was by name.
1107 Testing the substitution function
1109 If the replace modifier is set, the pcre2_substitute() function is
1111 called instead of one of the matching functions. Note that replacement
1112 strings cannot contain commas, because a comma signifies the end of a
1113 modifier. This is not thought to be an issue in a test program.
1114 Unlike subject strings, pcre2test does not process replacement strings
1116 for escape sequences. In UTF mode, a replacement string is checked to
1117 see if it is a valid UTF-8 string. If so, it is correctly converted to
1118 a UTF string of the appropriate code unit width. If it is not a valid
1119 UTF-8 string, the individual code units are copied directly. This pro‐
1120 vides a means of passing an invalid UTF-8 string for testing purposes.
1121 The following modifiers set options (in additional to the normal match
1123 options) for pcre2_substitute():
1124 global PCRE2_SUBSTITUTE_GLOBAL
1126 substitute_extended PCRE2_SUBSTITUTE_EXTENDED
1127 substitute_overflow_length PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
1128 substitute_unknown_unset PCRE2_SUBSTITUTE_UNKNOWN_UNSET
1129 substitute_unset_empty PCRE2_SUBSTITUTE_UNSET_EMPTY
1130 After a successful substitution, the modified string is output, pre‐
1133 ceded by the number of replacements. This may be zero if there were no
1134 matches. Here is a simple example of a substitution test:
1135 /abc/replace=xxx
1137 =abc=abc=
1138 1: =xxx=abc=
1139 =abc=abc=\=global
1140 2: =xxx=xxx=
1141 Subject and replacement strings should be kept relatively short (fewer
1143 than 256 characters) for substitution tests, as fixed-size buffers are
1144 used. To make it easy to test for buffer overflow, if the replacement
1145 string starts with a number in square brackets, that number is passed
1146 to pcre2_substitute() as the size of the output buffer, with the
1147 replacement string starting at the next character. Here is an example
1148 that tests the edge case:
1149 /abc/
1151 123abc123\=replace=[10]XYZ
1152 1: 123XYZ123
1153 123abc123\=replace=[9]XYZ
1154 Failed: error -47: no more memory
1155 The default action of pcre2_substitute() is to return
1157 PCRE2_ERROR_NOMEMORY when the output buffer is too small. However, if
1158 the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set (by using the sub‐
1159 stitute_overflow_length modifier), pcre2_substitute() continues to go
1160 through the motions of matching and substituting, in order to compute
1161 the size of buffer that is required. When this happens, pcre2test shows
1162 the required buffer length (which includes space for the trailing zero)
1163 as part of the error message. For example:
1164 /abc/substitute_overflow_length
1166 123abc123\=replace=[9]XYZ
1167 Failed: error -47: no more memory: 10 code units are needed
1168 A replacement string is ignored with POSIX and DFA matching. Specifying
1170 partial matching provokes an error return ("bad option value") from
1171 pcre2_substitute().
1172 Setting the JIT stack size
1174 The jitstack modifier provides a way of setting the maximum stack size
1176 that is used by the just-in-time optimization code. It is ignored if
1177 JIT optimization is not being used. The value is a number of kilobytes.
1178 Providing a stack that is larger than the default 32K is necessary only
1179 for very complicated patterns.
1180 Setting match and recursion limits
1182 The match_limit and recursion_limit modifiers set the appropriate lim‐
1184 its in the match context. These values are ignored when the find_limits
1185 modifier is specified.
1186 Finding minimum limits
1188 If the find_limits modifier is present, pcre2test calls pcre2_match()
1190 several times, setting different values in the match context via
1191 pcre2_set_match_limit() and pcre2_set_recursion_limit() until it finds
1192 the minimum values for each parameter that allow pcre2_match() to com‐
1193 plete without error.
1194 If JIT is being used, only the match limit is relevant. If DFA matching
1196 is being used, neither limit is relevant, and this modifier is ignored
1197 (with a warning message).
1198 The match_limit number is a measure of the amount of backtracking that
1200 takes place, and learning the minimum value can be instructive. For
1201 most simple matches, the number is quite small, but for patterns with
1202 very large numbers of matching possibilities, it can become large very
1203 quickly with increasing length of subject string. The
1204 match_limit_recursion number is a measure of how much stack (or, if
1205 PCRE2 is compiled with NO_RECURSE, how much heap) memory is needed to
1206 complete the match attempt.
1207 Showing MARK names
1209 The mark modifier causes the names from backtracking control verbs that
1212 are returned from calls to pcre2_match() to be displayed. If a mark is
1213 returned for a match, non-match, or partial match, pcre2test shows it.
1214 For a match, it is on a line by itself, tagged with "MK:". Otherwise,
1215 it is added to the non-match message.
1216 Showing memory usage
1218 The memory modifier causes pcre2test to log all memory allocation and
1220 freeing calls that occur during a match operation.
1221 Setting a starting offset
1223 The offset modifier sets an offset in the subject string at which
1225 matching starts. Its value is a number of code units, not characters.
1226 Setting an offset limit
1228 The offset_limit modifier sets a limit for unanchored matches. If a
1230 match cannot be found starting at or before this offset in the subject,
1231 a "no match" return is given. The data value is a number of code units,
1232 not characters. When this modifier is used, the use_offset_limit modi‐
1233 fier must have been set for the pattern; if not, an error is generated.
1234 Setting the size of the output vector
1236 The ovector modifier applies only to the subject line in which it
1238 appears, though of course it can also be used to set a default in a
1239 #subject command. It specifies the number of pairs of offsets that are
1240 available for storing matching information. The default is 15.
1241 A value of zero is useful when testing the POSIX API because it causes
1243 regexec() to be called with a NULL capture vector. When not testing the
1244 POSIX API, a value of zero is used to cause pcre2_match_data_cre‐
1245 ate_from_pattern() to be called, in order to create a match block of
1246 exactly the right size for the pattern. (It is not possible to create a
1247 match block with a zero-length ovector; there is always at least one
1248 pair of offsets.)
1249 Passing the subject as zero-terminated
1251 By default, the subject string is passed to a native API matching func‐
1253 tion with its correct length. In order to test the facility for passing
1254 a zero-terminated string, the zero_terminate modifier is provided. It
1255 causes the length to be passed as PCRE2_ZERO_TERMINATED. (When matching
1256 via the POSIX interface, this modifier has no effect, as there is no
1257 facility for passing a length.)
1258 When testing pcre2_substitute(), this modifier also has the effect of
1260 passing the replacement string as zero-terminated.
1261 Passing a NULL context
1263 Normally, pcre2test passes a context block to pcre2_match(),
1265 pcre2_dfa_match() or pcre2_jit_match(). If the null_context modifier is
1266 set, however, NULL is passed. This is for testing that the matching
1267 functions behave correctly in this case (they use default values). This
1268 modifier cannot be used with the find_limits modifier or when testing
1269 the substitution function.
1270
1272 By default, pcre2test uses the standard PCRE2 matching function,
1274 pcre2_match() to match each subject line. PCRE2 also supports an alter‐
1275 native matching function, pcre2_dfa_match(), which operates in a dif‐
1276 ferent way, and has some restrictions. The differences between the two
1277 functions are described in the pcre2matching documentation.
1278 If the dfa modifier is set, the alternative matching function is used.
1280 This function finds all possible matches at a given point in the sub‐
1281 ject. If, however, the dfa_shortest modifier is set, processing stops
1282 after the first match is found. This is always the shortest possible
1283 match.
1284
1286 This section describes the output when the normal matching function,
1288 pcre2_match(), is being used.
1289 When a match succeeds, pcre2test outputs the list of captured sub‐
1291 strings, starting with number 0 for the string that matched the whole
1292 pattern. Otherwise, it outputs "No match" when the return is
1293 PCRE2_ERROR_NOMATCH, or "Partial match:" followed by the partially
1294 matching substring when the return is PCRE2_ERROR_PARTIAL. (Note that
1295 this is the entire substring that was inspected during the partial
1296 match; it may include characters before the actual match start if a
1297 lookbehind assertion, \K, \b, or \B was involved.)
1298 For any other return, pcre2test outputs the PCRE2 negative error number
1300 and a short descriptive phrase. If the error is a failed UTF string
1301 check, the code unit offset of the start of the failing character is
1302 also output. Here is an example of an interactive pcre2test run.
1303 $ pcre2test
1305 PCRE2 version 9.00 2014-05-10
1306 re> /^abc(\d+)/
1308 data> abc123
1309 0: abc123
1310 1: 123
1311 data> xyz
1312 No match
1313 Unset capturing substrings that are not followed by one that is set are
1315 not shown by pcre2test unless the allcaptures modifier is specified. In
1316 the following example, there are two capturing substrings, but when the
1317 first data line is matched, the second, unset substring is not shown.
1318 An "internal" unset substring is shown as "<unset>", as for the second
1319 data line.
1320 re> /(a)|(b)/
1322 data> a
1323 0: a
1324 1: a
1325 data> b
1326 0: b
1327 1: <unset>
1328 2: b
1329 If the strings contain any non-printing characters, they are output as
1331 \xhh escapes if the value is less than 256 and UTF mode is not set.
1332 Otherwise they are output as \x{hh...} escapes. See below for the defi‐
1333 nition of non-printing characters. If the aftertext modifier is set,
1334 the output for substring 0 is followed by the the rest of the subject
1335 string, identified by "0+" like this:
1336 re> /cat/aftertext
1338 data> cataract
1339 0: cat
1340 0+ aract
1341 If global matching is requested, the results of successive matching
1343 attempts are output in sequence, like this:
1344 re> /\Bi(\w\w)/g
1346 data> Mississippi
1347 0: iss
1348 1: ss
1349 0: iss
1350 1: ss
1351 0: ipp
1352 1: pp
1353 "No match" is output only if the first match attempt fails. Here is an
1355 example of a failure message (the offset 4 that is specified by the
1356 offset modifier is past the end of the subject string):
1357 re> /xyz/
1359 data> xyz\=offset=4
1360 Error -24 (bad offset value)
1361 Note that whereas patterns can be continued over several lines (a plain
1363 ">" prompt is used for continuations), subject lines may not. However
1364 newlines can be included in a subject by means of the \n escape (or \r,
1365 \r\n, etc., depending on the newline sequence setting).
1366
1368 When the alternative matching function, pcre2_dfa_match(), is used, the
1370 output consists of a list of all the matches that start at the first
1371 point in the subject where there is at least one match. For example:
1372 re> /(tang|tangerine|tan)/
1374 data> yellow tangerine\=dfa
1375 0: tangerine
1376 1: tang
1377 2: tan
1378 Using the normal matching function on this data finds only "tang". The
1380 longest matching string is always given first (and numbered zero).
1381 After a PCRE2_ERROR_PARTIAL return, the output is "Partial match:",
1382 followed by the partially matching substring. Note that this is the
1383 entire substring that was inspected during the partial match; it may
1384 include characters before the actual match start if a lookbehind asser‐
1385 tion, \b, or \B was involved. (\K is not supported for DFA matching.)
1386 If global matching is requested, the search for further matches resumes
1388 at the end of the longest match. For example:
1389 re> /(tang|tangerine|tan)/g
1391 data> yellow tangerine and tangy sultana\=dfa
1392 0: tangerine
1393 1: tang
1394 2: tan
1395 0: tang
1396 1: tan
1397 0: tan
1398 The alternative matching function does not support substring capture,
1400 so the modifiers that are concerned with captured substrings are not
1401 relevant.
1402
1404 When the alternative matching function has given the PCRE2_ERROR_PAR‐
1406 TIAL return, indicating that the subject partially matched the pattern,
1407 you can restart the match with additional subject data by means of the
1408 dfa_restart modifier. For example:
1409 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
1411 data> 23ja\=P,dfa
1412 Partial match: 23ja
1413 data> n05\=dfa,dfa_restart
1414 0: n05
1415 For further information about partial matching, see the pcre2partial
1417 documentation.
1418
1420 If the pattern contains any callout requests, pcre2test's callout func‐
1422 tion is called during matching unless callout_none is specified. This
1423 works with both matching functions.
1424 The callout function in pcre2test returns zero (carry on matching) by
1426 default, but you can use a callout_fail modifier in a subject line (as
1427 described above) to change this and other parameters of the callout.
1428 Inserting callouts can be helpful when using pcre2test to check compli‐
1430 cated regular expressions. For further information about callouts, see
1431 the pcre2callout documentation.
1432 The output for callouts with numerical arguments and those with string
1434 arguments is slightly different.
1435 Callouts with numerical arguments
1437 By default, the callout function displays the callout number, the start
1439 and current positions in the subject text at the callout time, and the
1440 next pattern item to be tested. For example:
1441 --->pqrabcdef
1443 0 ^ ^ \d
1444 This output indicates that callout number 0 occurred for a match
1446 attempt starting at the fourth character of the subject string, when
1447 the pointer was at the seventh character, and when the next pattern
1448 item was \d. Just one circumflex is output if the start and current
1449 positions are the same, or if the current position precedes the start
1450 position, which can happen if the callout is in a lookbehind assertion.
1451 Callouts numbered 255 are assumed to be automatic callouts, inserted as
1453 a result of the /auto_callout pattern modifier. In this case, instead
1454 of showing the callout number, the offset in the pattern, preceded by a
1455 plus, is output. For example:
1456 re> /\d?[A-E]\*/auto_callout
1458 data> E*
1459 --->E*
1460 +0 ^ \d?
1461 +3 ^ [A-E]
1462 +8 ^^ \*
1463 +10 ^ ^
1464 0: E*
1465 If a pattern contains (*MARK) items, an additional line is output when‐
1467 ever a change of latest mark is passed to the callout function. For
1468 example:
1469 re> /a(*MARK:X)bc/auto_callout
1471 data> abc
1472 --->abc
1473 +0 ^ a
1474 +1 ^^ (*MARK:X)
1475 +10 ^^ b
1476 Latest Mark: X
1477 +11 ^ ^ c
1478 +12 ^ ^
1479 0: abc
1480 The mark changes between matching "a" and "b", but stays the same for
1482 the rest of the match, so nothing more is output. If, as a result of
1483 backtracking, the mark reverts to being unset, the text "<unset>" is
1484 output.
1485 Callouts with string arguments
1487 The output for a callout with a string argument is similar, except that
1489 instead of outputting a callout number before the position indicators,
1490 the callout string and its offset in the pattern string are output
1491 before the reflection of the subject string, and the subject string is
1492 reflected for each callout. For example:
1493 re> /^ab(?C'first')cd(?C"second")ef/
1495 data> abcdefg
1496 Callout (7): 'first'
1497 --->abcdefg
1498 ^ ^ c
1499 Callout (20): "second"
1500 --->abcdefg
1501 ^ ^ e
1502 0: abcdef
1503
1506 When pcre2test is outputting text in the compiled version of a pattern,
1508 bytes other than 32-126 are always treated as non-printing characters
1509 and are therefore shown as hex escapes.
1510 When pcre2test is outputting text that is a matched part of a subject
1512 string, it behaves in the same way, unless a different locale has been
1513 set for the pattern (using the locale modifier). In this case, the
1514 isprint() function is used to distinguish printing and non-printing
1515 characters.
1516
1518 It is possible to save compiled patterns on disc or elsewhere, and
1520 reload them later, subject to a number of restrictions. JIT data cannot
1521 be saved. The host on which the patterns are reloaded must be running
1522 the same version of PCRE2, with the same code unit width, and must also
1523 have the same endianness, pointer width and PCRE2_SIZE type. Before
1524 compiled patterns can be saved they must be serialized, that is, con‐
1525 verted to a stream of bytes. A single byte stream may contain any num‐
1526 ber of compiled patterns, but they must all use the same character
1527 tables. A single copy of the tables is included in the byte stream (its
1528 size is 1088 bytes).
1529 The functions whose names begin with pcre2_serialize_ are used for
1531 serializing and de-serializing. They are described in the pcre2serial‐
1532 ize documentation. In this section we describe the features of
1533 pcre2test that can be used to test these functions.
1534 When a pattern with push modifier is successfully compiled, it is
1536 pushed onto a stack of compiled patterns, and pcre2test expects the
1537 next line to contain a new pattern (or command) instead of a subject
1538 line. By contrast, the pushcopy modifier causes a copy of the compiled
1539 pattern to be stacked, leaving the original available for immediate
1540 matching. By using push and/or pushcopy, a number of patterns can be
1541 compiled and retained. These modifiers are incompatible with posix, and
1542 control modifiers that act at match time are ignored (with a message)
1543 for the stacked patterns. The jitverify modifier applies only at com‐
1544 pile time.
1545 The command
1547 #save <filename>
1549 causes all the stacked patterns to be serialized and the result written
1551 to the named file. Afterwards, all the stacked patterns are freed. The
1552 command
1553 #load <filename>
1555 reads the data in the file, and then arranges for it to be de-serial‐
1557 ized, with the resulting compiled patterns added to the pattern stack.
1558 The pattern on the top of the stack can be retrieved by the #pop com‐
1559 mand, which must be followed by lines of subjects that are to be
1560 matched with the pattern, terminated as usual by an empty line or end
1561 of file. This command may be followed by a modifier list containing
1562 only control modifiers that act after a pattern has been compiled. In
1563 particular, hex, posix, posix_nosub, push, and pushcopy are not
1564 allowed, nor are any option-setting modifiers. The JIT modifiers are,
1565 however permitted. Here is an example that saves and reloads two pat‐
1566 terns.
1567 /abc/push
1569 /xyz/push
1570 #save tempfile
1571 #load tempfile
1572 #pop info
1573 xyz
1574 #pop jit,bincode
1576 abc
1577 If jitverify is used with #pop, it does not automatically imply jit,
1579 which is different behaviour from when it is used on a pattern.
1580 The #popcopy command is analagous to the pushcopy modifier in that it
1582 makes current a copy of the topmost stack pattern, leaving the original
1583 still on the stack.
1584
1586 pcre2(3), pcre2api(3), pcre2callout(3), pcre2jit, pcre2matching(3),
1588 pcre2partial(d), pcre2pattern(3), pcre2serialize(3).
1589
1591 Philip Hazel
1593 University Computing Service
1594 Cambridge, England.
1595
1597 Last updated: 28 December 2016
1599 Copyright (c) 1997-2016 University of Cambridge.
1600PCRE 10.23 28 December 2016 PCRE2TEST(1)