1 PCRE2TEST(1) General Commands Manual PCRE2TEST(1)
6 pcre2test - a program for testing Perl-compatible regular expressions.
10 pcre2test [options] [input file [output file]]
12 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.
19 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
27 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
40 PCRE2's 8-BIT, 16-BIT AND 32-BIT LIBRARIES
42 Different versions of the PCRE2 library can be built to support charac-
43 ter strings that are encoded in 8-bit, 16-bit, or 32-bit code units.
44 One, two, or all three of these libraries may be simultaneously
45 installed. The pcre2test program can be used to test all the libraries.
46 However, its own input and output are always in 8-bit format. When
47 testing the 16-bit or 32-bit libraries, patterns and subject strings
48 are converted to 16-bit or 32-bit format before being passed to the
49 library functions. Results are converted back to 8-bit code units for
52 In the rest of this document, the names of library functions and struc-
53 tures are given in generic form, for example, pcre_compile(). The
54 actual names used in the libraries have a suffix _8, _16, or _32, as
60 Input to pcre2test is processed line by line, either by calling the C
61 library's fgets() function, or via the libreadline library. In some
62 Windows environments character 26 (hex 1A) causes an immediate end of
63 file, and no further data is read, so this character should be avoided
64 unless you really want that action.
66 The input is processed using using C's string functions, so must not
67 contain binary zeros, even though in Unix-like environments, fgets()
68 treats any bytes other than newline as data characters. An error is
69 generated if a binary zero is encountered. By default subject lines are
70 processed for backslash escapes, which makes it possible to include any
71 data value in strings that are passed to the library for matching. For
72 patterns, there is a facility for specifying some or all of the 8-bit
73 input characters as hexadecimal pairs, which makes it possible to
76 Input for the 16-bit and 32-bit libraries
78 When testing the 16-bit or 32-bit libraries, there is a need to be able
79 to generate character code points greater than 255 in the strings that
80 are passed to the library. For subject lines, backslash escapes can be
81 used. In addition, when the utf modifier (see "Setting compilation
82 options" below) is set, the pattern and any following subject lines are
83 interpreted as UTF-8 strings and translated to UTF-16 or UTF-32 as
86 For non-UTF testing of wide characters, the utf8_input modifier can be
87 used. This is mutually exclusive with utf, and is allowed only in
88 16-bit or 32-bit mode. It causes the pattern and following subject
89 lines to be treated as UTF-8 according to the original definition (RFC
90 2279), which allows for character values up to 0x7fffffff. Each charac-
91 ter is placed in one 16-bit or 32-bit code unit (in the 16-bit case,
92 values greater than 0xffff cause an error to occur).
94 UTF-8 (in its original definition) is not capable of encoding values
95 greater than 0x7fffffff, but such values can be handled by the 32-bit
96 library. When testing this library in non-UTF mode with utf8_input set,
97 if any character is preceded by the byte 0xff (which is an invalid byte
98 in UTF-8) 0x80000000 is added to the character's value. This is the
99 only way of passing such code points in a pattern string. For subject
100 strings, using an escape sequence is preferable.
105 -8 If the 8-bit library has been built, this option causes it to
106 be used (this is the default). If the 8-bit library has not
107 been built, this option causes an error.
109 -16 If the 16-bit library has been built, this option causes it
110 to be used. If only the 16-bit library has been built, this
111 is the default. If the 16-bit library has not been built,
112 this option causes an error.
114 -32 If the 32-bit library has been built, this option causes it
115 to be used. If only the 32-bit library has been built, this
116 is the default. If the 32-bit library has not been built,
117 this option causes an error.
119 -ac Behave as if each pattern has the auto_callout modifier, that
120 is, insert automatic callouts into every pattern that is com-
123 -AC As for -ac, but in addition behave as if each subject line
124 has the callout_extra modifier, that is, show additional
125 information from callouts.
127 -b Behave as if each pattern has the fullbincode modifier; the
128 full internal binary form of the pattern is output after com-
131 -C Output the version number of the PCRE2 library, and all
132 available information about the optional features that are
133 included, and then exit with zero exit code. All other
134 options are ignored. If both -C and -LM are present, which-
135 ever is first is recognized.
137 -C option Output information about a specific build-time option, then
138 exit. This functionality is intended for use in scripts such
139 as RunTest. The following options output the value and set
140 the exit code as indicated:
142 ebcdic-nl the code for LF (= NL) in an EBCDIC environment:
144 0 if used in an ASCII environment
145 exit code is always 0
146 linksize the configured internal link size (2, 3, or 4)
147 exit code is set to the link size
148 newline the default newline setting:
149 CR, LF, CRLF, ANYCRLF, ANY, or NUL
150 exit code is always 0
151 bsr the default setting for what \R matches:
153 exit code is always 0
155 The following options output 1 for true or 0 for false, and
156 set the exit code to the same value:
158 backslash-C \C is supported (not locked out)
159 ebcdic compiled for an EBCDIC environment
160 jit just-in-time support is available
161 pcre2-16 the 16-bit library was built
162 pcre2-32 the 32-bit library was built
163 pcre2-8 the 8-bit library was built
164 unicode Unicode support is available
166 If an unknown option is given, an error message is output;
169 -d Behave as if each pattern has the debug modifier; the inter-
170 nal form and information about the compiled pattern is output
171 after compilation; -d is equivalent to -b -i.
173 -dfa Behave as if each subject line has the dfa modifier; matching
174 is done using the pcre2_dfa_match() function instead of the
175 default pcre2_match().
177 -error number[,number,...]
178 Call pcre2_get_error_message() for each of the error numbers
179 in the comma-separated list, display the resulting messages
180 on the standard output, then exit with zero exit code. The
181 numbers may be positive or negative. This is a convenience
182 facility for PCRE2 maintainers.
184 -help Output a brief summary these options and then exit.
186 -i Behave as if each pattern has the info modifier; information
187 about the compiled pattern is given after compilation.
189 -jit Behave as if each pattern line has the jit modifier; after
190 successful compilation, each pattern is passed to the just-
191 in-time compiler, if available.
194 Behave as if each pattern line has the jitverify modifier;
195 after successful compilation, each pattern is passed to the
196 just-in-time compiler, if available, and the use of JIT is
199 -LM List modifiers: write a list of available pattern and subject
200 modifiers to the standard output, then exit with zero exit
201 code. All other options are ignored. If both -C and -LM are
202 present, whichever is first is recognized.
204 -pattern modifier-list
205 Behave as if each pattern line contains the given modifiers.
207 -q Do not output the version number of pcre2test at the start of
210 -S size On Unix-like systems, set the size of the run-time stack to
211 size mebibytes (units of 1024*1024 bytes).
213 -subject modifier-list
214 Behave as if each subject line contains the given modifiers.
216 -t Run each compile and match many times with a timer, and out-
217 put the resulting times per compile or match. When JIT is
218 used, separate times are given for the initial compile and
219 the JIT compile. You can control the number of iterations
220 that are used for timing by following -t with a number (as a
221 separate item on the command line). For example, "-t 1000"
222 iterates 1000 times. The default is to iterate 500,000 times.
224 -tm This is like -t except that it times only the matching phase,
225 not the compile phase.
227 -T -TM These behave like -t and -tm, but in addition, at the end of
228 a run, the total times for all compiles and matches are out-
231 -version Output the PCRE2 version number and then exit.
236 If pcre2test is given two filename arguments, it reads from the first
237 and writes to the second. If the first name is "-", input is taken from
238 the standard input. If pcre2test is given only one argument, it reads
239 from that file and writes to stdout. Otherwise, it reads from stdin and
242 When pcre2test is built, a configuration option can specify that it
243 should be linked with the libreadline or libedit library. When this is
244 done, if the input is from a terminal, it is read using the readline()
245 function. This provides line-editing and history facilities. The output
246 from the -help option states whether or not readline() will be used.
248 The program handles any number of tests, each of which consists of a
249 set of input lines. Each set starts with a regular expression pattern,
250 followed by any number of subject lines to be matched against that pat-
251 tern. In between sets of test data, command lines that begin with # may
252 appear. This file format, with some restrictions, can also be processed
253 by the perltest.sh script that is distributed with PCRE2 as a means of
254 checking that the behaviour of PCRE2 and Perl is the same. For a speci-
255 fication of perltest.sh, see the comments near its beginning.
257 When the input is a terminal, pcre2test prompts for each line of input,
258 using "re>" to prompt for regular expression patterns, and "data>" to
259 prompt for subject lines. Command lines starting with # can be entered
260 only in response to the "re>" prompt.
262 Each subject line is matched separately and independently. If you want
263 to do multi-line matches, you have to use the \n escape sequence (or \r
264 or \r\n, etc., depending on the newline setting) in a single line of
265 input to encode the newline sequences. There is no limit on the length
266 of subject lines; the input buffer is automatically extended if it is
267 too small. There are replication features that makes it possible to
268 generate long repetitive pattern or subject lines without having to
269 supply them explicitly.
271 An empty line or the end of the file signals the end of the subject
272 lines for a test, at which point a new pattern or command line is
273 expected if there is still input to be read.
278 In between sets of test data, a line that begins with # is interpreted
279 as a command line. If the first character is followed by white space or
280 an exclamation mark, the line is treated as a comment, and ignored.
281 Otherwise, the following commands are recognized:
285 Subsequent patterns automatically have the PCRE2_NEVER_UTF and
286 PCRE2_NEVER_UCP options set, which locks out the use of the PCRE2_UTF
287 and PCRE2_UCP options and the use of (*UTF) and (*UCP) at the start of
288 patterns. This command also forces an error if a subsequent pattern
289 contains any occurrences of \P, \p, or \X, which are still supported
290 when PCRE2_UTF is not set, but which require Unicode property support
291 to be included in the library.
293 This is a trigger guard that is used in test files to ensure that UTF
294 or Unicode property tests are not accidentally added to files that are
295 used when Unicode support is not included in the library. Setting
296 PCRE2_NEVER_UTF and PCRE2_NEVER_UCP as a default can also be obtained
297 by the use of #pattern; the difference is that #forbid_utf cannot be
298 unset, and the automatic options are not displayed in pattern informa-
299 tion, to avoid cluttering up test output.
303 This command is used to load a set of precompiled patterns from a file,
304 as described in the section entitled "Saving and restoring compiled
307 #newline_default [<newline-list>]
309 When PCRE2 is built, a default newline convention can be specified.
310 This determines which characters and/or character pairs are recognized
311 as indicating a newline in a pattern or subject string. The default can
312 be overridden when a pattern is compiled. The standard test files con-
313 tain tests of various newline conventions, but the majority of the
314 tests expect a single linefeed to be recognized as a newline by
315 default. Without special action the tests would fail when PCRE2 is com-
316 piled with either CR or CRLF as the default newline.
318 The #newline_default command specifies a list of newline types that are
319 acceptable as the default. The types must be one of CR, LF, CRLF, ANY-
320 CRLF, ANY, or NUL (in upper or lower case), for example:
322 #newline_default LF Any anyCRLF
324 If the default newline is in the list, this command has no effect. Oth-
325 erwise, except when testing the POSIX API, a newline modifier that
326 specifies the first newline convention in the list (LF in the above
327 example) is added to any pattern that does not already have a newline
328 modifier. If the newline list is empty, the feature is turned off. This
329 command is present in a number of the standard test input files.
331 When the POSIX API is being tested there is no way to override the
332 default newline convention, though it is possible to set the newline
333 convention from within the pattern. A warning is given if the posix or
334 posix_nosub modifier is used when #newline_default would set a default
335 for the non-POSIX API.
337 #pattern <modifier-list>
339 This command sets a default modifier list that applies to all subse-
340 quent patterns. Modifiers on a pattern can change these settings.
344 The appearance of this line causes all subsequent modifier settings to
345 be checked for compatibility with the perltest.sh script, which is used
346 to confirm that Perl gives the same results as PCRE2. Also, apart from
347 comment lines, #pattern commands, and #subject commands that set or
348 unset "mark", no command lines are permitted, because they and many of
349 the modifiers are specific to pcre2test, and should not be used in test
350 files that are also processed by perltest.sh. The #perltest command
351 helps detect tests that are accidentally put in the wrong file.
354 #popcopy [<modifiers>]
356 These commands are used to manipulate the stack of compiled patterns,
357 as described in the section entitled "Saving and restoring compiled
362 This command is used to save a set of compiled patterns to a file, as
363 described in the section entitled "Saving and restoring compiled pat-
366 #subject <modifier-list>
368 This command sets a default modifier list that applies to all subse-
369 quent subject lines. Modifiers on a subject line can change these set-
375 Modifier lists are used with both pattern and subject lines. Items in a
376 list are separated by commas followed by optional white space. Trailing
377 whitespace in a modifier list is ignored. Some modifiers may be given
378 for both patterns and subject lines, whereas others are valid only for
379 one or the other. Each modifier has a long name, for example
380 "anchored", and some of them must be followed by an equals sign and a
381 value, for example, "offset=12". Values cannot contain comma charac-
382 ters, but may contain spaces. Modifiers that do not take values may be
383 preceded by a minus sign to turn off a previous setting.
385 A few of the more common modifiers can also be specified as single let-
386 ters, for example "i" for "caseless". In documentation, following the
387 Perl convention, these are written with a slash ("the /i modifier") for
388 clarity. Abbreviated modifiers must all be concatenated in the first
389 item of a modifier list. If the first item is not recognized as a long
390 modifier name, it is interpreted as a sequence of these abbreviations.
393 /abc/ig,newline=cr,jit=3
395 This is a pattern line whose modifier list starts with two one-letter
396 modifiers (/i and /g). The lower-case abbreviated modifiers are the
397 same as used in Perl.
402 A pattern line must start with one of the following characters (common
403 symbols, excluding pattern meta-characters):
405 / ! " ' ` - = _ : ; , % & @ ~
407 This is interpreted as the pattern's delimiter. A regular expression
408 may be continued over several input lines, in which case the newline
409 characters are included within it. It is possible to include the delim-
410 iter within the pattern by escaping it with a backslash, for example
414 If you do this, the escape and the delimiter form part of the pattern,
415 but since the delimiters are all non-alphanumeric, this does not affect
416 its interpretation. If the terminating delimiter is immediately fol-
417 lowed by a backslash, for example,
421 then a backslash is added to the end of the pattern. This is done to
422 provide a way of testing the error condition that arises if a pattern
423 finishes with a backslash, because
427 is interpreted as the first line of a pattern that starts with "abc/",
428 causing pcre2test to read the next line as a continuation of the regu-
431 A pattern can be followed by a modifier list (details below).
436 Before each subject line is passed to pcre2_match() or
437 pcre2_dfa_match(), leading and trailing white space is removed, and the
438 line is scanned for backslash escapes, unless the subject_literal modi-
439 fier was set for the pattern. The following provide a means of encoding
440 non-printing characters in a visible way:
447 \r carriage return (\x0d)
449 \v vertical tab (\x0b)
450 \nnn octal character (up to 3 octal digits); always
451 a byte unless > 255 in UTF-8 or 16-bit or 32-bit mode
452 \o{dd...} octal character (any number of octal digits}
453 \xhh hexadecimal byte (up to 2 hex digits)
454 \x{hh...} hexadecimal character (any number of hex digits)
456 The use of \x{hh...} is not dependent on the use of the utf modifier on
457 the pattern. It is recognized always. There may be any number of hexa-
458 decimal digits inside the braces; invalid values provoke error mes-
461 Note that \xhh specifies one byte rather than one character in UTF-8
462 mode; this makes it possible to construct invalid UTF-8 sequences for
463 testing purposes. On the other hand, \x{hh} is interpreted as a UTF-8
464 character in UTF-8 mode, generating more than one byte if the value is
465 greater than 127. When testing the 8-bit library not in UTF-8 mode,
466 \x{hh} generates one byte for values less than 256, and causes an error
469 In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
470 possible to construct invalid UTF-16 sequences for testing purposes.
472 In UTF-32 mode, all 4- to 8-digit \x{...} values are accepted. This
473 makes it possible to construct invalid UTF-32 sequences for testing
476 There is a special backslash sequence that specifies replication of one
479 \[<characters>]{<count>}
481 This makes it possible to test long strings without having to provide
482 them as part of the file. For example:
486 is converted to "abcabcabcabc". This feature does not support nesting.
487 To include a closing square bracket in the characters, code it as \x5D.
489 A backslash followed by an equals sign marks the end of the subject
490 string and the start of a modifier list. For example:
494 If the subject string is empty and \= is followed by whitespace, the
495 line is treated as a comment line, and is not used for matching. For
498 \= This is a comment.
499 abc\= This is an invalid modifier list.
501 A backslash followed by any other non-alphanumeric character just
502 escapes that character. A backslash followed by anything else causes an
503 error. However, if the very last character in the line is a backslash
504 (and there is no modifier list), it is ignored. This gives a way of
505 passing an empty line as data, since a real empty line terminates the
508 If the subject_literal modifier is set for a pattern, all subject lines
509 that follow are treated as literals, with no special treatment of back-
510 slashes. No replication is possible, and any subject modifiers must be
511 set as defaults by a #subject command.
516 There are several types of modifier that can appear in pattern lines.
517 Except where noted below, they may also be used in #pattern commands. A
518 pattern's modifier list can add to or override default modifiers that
519 were set by a previous #pattern command.
521 Setting compilation options
523 The following modifiers set options for pcre2_compile(). Most of them
524 set bits in the options argument of that function, but those whose
525 names start with PCRE2_EXTRA are additional options that are set in the
526 compile context. For the main options, there are some single-letter
527 abbreviations that are the same as Perl options. There is special han-
528 dling for /x: if a second x is present, PCRE2_EXTENDED is converted
529 into PCRE2_EXTENDED_MORE as in Perl. A third appearance adds
530 PCRE2_EXTENDED as well, though this makes no difference to the way
531 pcre2_compile() behaves. See pcre2api for a description of the effects
534 allow_empty_class set PCRE2_ALLOW_EMPTY_CLASS
535 allow_surrogate_escapes set PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES
536 alt_bsux set PCRE2_ALT_BSUX
537 alt_circumflex set PCRE2_ALT_CIRCUMFLEX
538 alt_verbnames set PCRE2_ALT_VERBNAMES
539 anchored set PCRE2_ANCHORED
540 auto_callout set PCRE2_AUTO_CALLOUT
541 bad_escape_is_literal set PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL
542 /i caseless set PCRE2_CASELESS
543 dollar_endonly set PCRE2_DOLLAR_ENDONLY
544 /s dotall set PCRE2_DOTALL
545 dupnames set PCRE2_DUPNAMES
546 endanchored set PCRE2_ENDANCHORED
547 /x extended set PCRE2_EXTENDED
548 /xx extended_more set PCRE2_EXTENDED_MORE
549 firstline set PCRE2_FIRSTLINE
550 literal set PCRE2_LITERAL
551 match_line set PCRE2_EXTRA_MATCH_LINE
552 match_unset_backref set PCRE2_MATCH_UNSET_BACKREF
553 match_word set PCRE2_EXTRA_MATCH_WORD
554 /m multiline set PCRE2_MULTILINE
555 never_backslash_c set PCRE2_NEVER_BACKSLASH_C
556 never_ucp set PCRE2_NEVER_UCP
557 never_utf set PCRE2_NEVER_UTF
558 /n no_auto_capture set PCRE2_NO_AUTO_CAPTURE
559 no_auto_possess set PCRE2_NO_AUTO_POSSESS
560 no_dotstar_anchor set PCRE2_NO_DOTSTAR_ANCHOR
561 no_start_optimize set PCRE2_NO_START_OPTIMIZE
562 no_utf_check set PCRE2_NO_UTF_CHECK
564 ungreedy set PCRE2_UNGREEDY
565 use_offset_limit set PCRE2_USE_OFFSET_LIMIT
568 As well as turning on the PCRE2_UTF option, the utf modifier causes all
569 non-printing characters in output strings to be printed using the
570 \x{hh...} notation. Otherwise, those less than 0x100 are output in hex
571 without the curly brackets. Setting utf in 16-bit or 32-bit mode also
572 causes pattern and subject strings to be translated to UTF-16 or
573 UTF-32, respectively, before being passed to library functions.
575 Setting compilation controls
577 The following modifiers affect the compilation process or request
578 information about the pattern. There are single-letter abbreviations
579 for some that are heavily used in the test files.
581 bsr=[anycrlf|unicode] specify \R handling
582 /B bincode show binary code without lengths
583 callout_info show callout information
584 convert=<options> request foreign pattern conversion
585 convert_glob_escape=c set glob escape character
586 convert_glob_separator=c set glob separator character
587 convert_length set convert buffer length
588 debug same as info,fullbincode
589 framesize show matching frame size
590 fullbincode show binary code with lengths
591 /I info show info about compiled pattern
592 hex unquoted characters are hexadecimal
593 jit[=<number>] use JIT
594 jitfast use JIT fast path
595 jitverify verify JIT use
596 locale=<name> use this locale
597 max_pattern_length=<n> set the maximum pattern length
598 memory show memory used
599 newline=<type> set newline type
600 null_context compile with a NULL context
601 parens_nest_limit=<n> set maximum parentheses depth
602 posix use the POSIX API
603 posix_nosub use the POSIX API with REG_NOSUB
604 push push compiled pattern onto the stack
605 pushcopy push a copy onto the stack
606 stackguard=<number> test the stackguard feature
607 subject_literal treat all subject lines as literal
608 tables=[0|1|2] select internal tables
609 use_length do not zero-terminate the pattern
610 utf8_input treat input as UTF-8
612 The effects of these modifiers are described in the following sections.
614 Newline and \R handling
616 The bsr modifier specifies what \R in a pattern should match. If it is
617 set to "anycrlf", \R matches CR, LF, or CRLF only. If it is set to
618 "unicode", \R matches any Unicode newline sequence. The default can be
619 specified when PCRE2 is built; if it is not, the default is set to Uni-
622 The newline modifier specifies which characters are to be interpreted
623 as newlines, both in the pattern and in subject lines. The type must be
624 one of CR, LF, CRLF, ANYCRLF, ANY, or NUL (in upper or lower case).
626 Information about a pattern
628 The debug modifier is a shorthand for info,fullbincode, requesting all
629 available information.
631 The bincode modifier causes a representation of the compiled code to be
632 output after compilation. This information does not contain length and
633 offset values, which ensures that the same output is generated for dif-
634 ferent internal link sizes and different code unit widths. By using
635 bincode, the same regression tests can be used in different environ-
638 The fullbincode modifier, by contrast, does include length and offset
639 values. This is used in a few special tests that run only for specific
640 code unit widths and link sizes, and is also useful for one-off tests.
642 The info modifier requests information about the compiled pattern
643 (whether it is anchored, has a fixed first character, and so on). The
644 information is obtained from the pcre2_pattern_info() function. Here
645 are some typical examples:
647 re> /(?i)(^a|^b)/m,info
648 Capturing subpattern count = 1
649 Compile options: multiline
650 Overall options: caseless multiline
651 First code unit at start or follows newline
652 Subject length lower bound = 1
655 Capturing subpattern count = 0
656 Compile options: <none>
657 Overall options: caseless
658 First code unit = 'a' (caseless)
659 Last code unit = 'c' (caseless)
660 Subject length lower bound = 3
662 "Compile options" are those specified by modifiers; "overall options"
663 have added options that are taken or deduced from the pattern. If both
664 sets of options are the same, just a single "options" line is output;
665 if there are no options, the line is omitted. "First code unit" is
666 where any match must start; if there is more than one they are listed
667 as "starting code units". "Last code unit" is the last literal code
668 unit that must be present in any match. This is not necessarily the
669 last character. These lines are omitted if no starting or ending code
672 The framesize modifier shows the size, in bytes, of the storage frames
673 used by pcre2_match() for handling backtracking. The size depends on
674 the number of capturing parentheses in the pattern.
676 The callout_info modifier requests information about all the callouts
677 in the pattern. A list of them is output at the end of any other infor-
678 mation that is requested. For each callout, either its number or string
679 is given, followed by the item that follows it in the pattern.
681 Passing a NULL context
683 Normally, pcre2test passes a context block to pcre2_compile(). If the
684 null_context modifier is set, however, NULL is passed. This is for
685 testing that pcre2_compile() behaves correctly in this case (it uses
688 Specifying pattern characters in hexadecimal
690 The hex modifier specifies that the characters of the pattern, except
691 for substrings enclosed in single or double quotes, are to be inter-
692 preted as pairs of hexadecimal digits. This feature is provided as a
693 way of creating patterns that contain binary zeros and other non-print-
694 ing characters. White space is permitted between pairs of digits. For
695 example, this pattern contains three characters:
699 Parts of such a pattern are taken literally if quoted. This pattern
700 contains nine characters, only two of which are specified in hexadeci-
705 Either single or double quotes may be used. There is no way of includ-
706 ing the delimiter within a substring. The hex and expand modifiers are
709 Specifying the pattern's length
711 By default, patterns are passed to the compiling functions as zero-ter-
712 minated strings but can be passed by length instead of being zero-ter-
713 minated. The use_length modifier causes this to happen. Using a length
714 happens automatically (whether or not use_length is set) when hex is
715 set, because patterns specified in hexadecimal may contain binary
718 If hex or use_length is used with the POSIX wrapper API (see "Using the
719 POSIX wrapper API" below), the REG_PEND extension is used to pass the
722 Specifying wide characters in 16-bit and 32-bit modes
724 In 16-bit and 32-bit modes, all input is automatically treated as UTF-8
725 and translated to UTF-16 or UTF-32 when the utf modifier is set. For
726 testing the 16-bit and 32-bit libraries in non-UTF mode, the utf8_input
727 modifier can be used. It is mutually exclusive with utf. Input lines
728 are interpreted as UTF-8 as a means of specifying wide characters. More
729 details are given in "Input encoding" above.
731 Generating long repetitive patterns
733 Some tests use long patterns that are very repetitive. Instead of cre-
734 ating a very long input line for such a pattern, you can use a special
735 repetition feature, similar to the one described for subject lines
736 above. If the expand modifier is present on a pattern, parts of the
737 pattern that have the form
739 \[<characters>]{<count>}
741 are expanded before the pattern is passed to pcre2_compile(). For exam-
742 ple, \[AB]{6000} is expanded to "ABAB..." 6000 times. This construction
743 cannot be nested. An initial "\[" sequence is recognized only if "]{"
744 followed by decimal digits and "}" is found later in the pattern. If
745 not, the characters remain in the pattern unaltered. The expand and hex
746 modifiers are mutually exclusive.
748 If part of an expanded pattern looks like an expansion, but is really
749 part of the actual pattern, unwanted expansion can be avoided by giving
750 two values in the quantifier. For example, \[AB]{6000,6000} is not rec-
751 ognized as an expansion item.
753 If the info modifier is set on an expanded pattern, the result of the
754 expansion is included in the information that is output.
758 Just-in-time (JIT) compiling is a heavyweight optimization that can
759 greatly speed up pattern matching. See the pcre2jit documentation for
760 details. JIT compiling happens, optionally, after a pattern has been
761 successfully compiled into an internal form. The JIT compiler converts
762 this to optimized machine code. It needs to know whether the match-time
763 options PCRE2_PARTIAL_HARD and PCRE2_PARTIAL_SOFT are going to be used,
764 because different code is generated for the different cases. See the
765 partial modifier in "Subject Modifiers" below for details of how these
766 options are specified for each match attempt.
768 JIT compilation is requested by the jit pattern modifier, which may
769 optionally be followed by an equals sign and a number in the range 0 to
770 7. The three bits that make up the number specify which of the three
771 JIT operating modes are to be compiled:
773 1 compile JIT code for non-partial matching
774 2 compile JIT code for soft partial matching
775 4 compile JIT code for hard partial matching
777 The possible values for the jit modifier are therefore:
780 1 normal matching only
781 2 soft partial matching only
782 3 normal and soft partial matching
783 4 hard partial matching only
784 6 soft and hard partial matching only
787 If no number is given, 7 is assumed. The phrase "partial matching"
788 means a call to pcre2_match() with either the PCRE2_PARTIAL_SOFT or the
789 PCRE2_PARTIAL_HARD option set. Note that such a call may return a com-
790 plete match; the options enable the possibility of a partial match, but
791 do not require it. Note also that if you request JIT compilation only
792 for partial matching (for example, jit=2) but do not set the partial
793 modifier on a subject line, that match will not use JIT code because
794 none was compiled for non-partial matching.
796 If JIT compilation is successful, the compiled JIT code will automati-
797 cally be used when an appropriate type of match is run, except when
798 incompatible run-time options are specified. For more details, see the
799 pcre2jit documentation. See also the jitstack modifier below for a way
800 of setting the size of the JIT stack.
802 If the jitfast modifier is specified, matching is done using the JIT
803 "fast path" interface, pcre2_jit_match(), which skips some of the san-
804 ity checks that are done by pcre2_match(), and of course does not work
805 when JIT is not supported. If jitfast is specified without jit, jit=7
808 If the jitverify modifier is specified, information about the compiled
809 pattern shows whether JIT compilation was or was not successful. If
810 jitverify is specified without jit, jit=7 is assumed. If JIT compila-
811 tion is successful when jitverify is set, the text "(JIT)" is added to
812 the first output line after a match or non match when JIT-compiled code
813 was actually used in the match.
817 The locale modifier must specify the name of a locale, for example:
819 /pattern/locale=fr_FR
821 The given locale is set, pcre2_maketables() is called to build a set of
822 character tables for the locale, and this is then passed to pcre2_com-
823 pile() when compiling the regular expression. The same tables are used
824 when matching the following subject lines. The locale modifier applies
825 only to the pattern on which it appears, but can be given in a #pattern
826 command if a default is needed. Setting a locale and alternate charac-
827 ter tables are mutually exclusive.
829 Showing pattern memory
831 The memory modifier causes the size in bytes of the memory used to hold
832 the compiled pattern to be output. This does not include the size of
833 the pcre2_code block; it is just the actual compiled data. If the pat-
834 tern is subsequently passed to the JIT compiler, the size of the JIT
835 compiled code is also output. Here is an example:
837 re> /a(b)c/jit,memory
838 Memory allocation (code space): 21
839 Memory allocation (JIT code): 1910
842 Limiting nested parentheses
844 The parens_nest_limit modifier sets a limit on the depth of nested
845 parentheses in a pattern. Breaching the limit causes a compilation
846 error. The default for the library is set when PCRE2 is built, but
847 pcre2test sets its own default of 220, which is required for running
848 the standard test suite.
850 Limiting the pattern length
852 The max_pattern_length modifier sets a limit, in code units, to the
853 length of pattern that pcre2_compile() will accept. Breaching the limit
854 causes a compilation error. The default is the largest number a
855 PCRE2_SIZE variable can hold (essentially unlimited).
857 Using the POSIX wrapper API
859 The posix and posix_nosub modifiers cause pcre2test to call PCRE2 via
860 the POSIX wrapper API rather than its native API. When posix_nosub is
861 used, the POSIX option REG_NOSUB is passed to regcomp(). The POSIX
862 wrapper supports only the 8-bit library. Note that it does not imply
863 POSIX matching semantics; for more detail see the pcre2posix documenta-
864 tion. The following pattern modifiers set options for the regcomp()
868 multiline REG_NEWLINE
870 ungreedy REG_UNGREEDY ) These options are not part of
871 ucp REG_UCP ) the POSIX standard
874 The regerror_buffsize modifier specifies a size for the error buffer
875 that is passed to regerror() in the event of a compilation error. For
878 /abc/posix,regerror_buffsize=20
880 This provides a means of testing the behaviour of regerror() when the
881 buffer is too small for the error message. If this modifier has not
882 been set, a large buffer is used.
884 The aftertext and allaftertext subject modifiers work as described
885 below. All other modifiers are either ignored, with a warning message,
888 The pattern is passed to regcomp() as a zero-terminated string by
889 default, but if the use_length or hex modifiers are set, the REG_PEND
890 extension is used to pass it by length.
892 Testing the stack guard feature
894 The stackguard modifier is used to test the use of pcre2_set_com-
895 pile_recursion_guard(), a function that is provided to enable stack
896 availability to be checked during compilation (see the pcre2api docu-
897 mentation for details). If the number specified by the modifier is
898 greater than zero, pcre2_set_compile_recursion_guard() is called to set
899 up callback from pcre2_compile() to a local function. The argument it
900 receives is the current nesting parenthesis depth; if this is greater
901 than the value given by the modifier, non-zero is returned, causing the
902 compilation to be aborted.
904 Using alternative character tables
906 The value specified for the tables modifier must be one of the digits
907 0, 1, or 2. It causes a specific set of built-in character tables to be
908 passed to pcre2_compile(). This is used in the PCRE2 tests to check be-
909 haviour with different character tables. The digit specifies the tables
912 0 do not pass any special character tables
913 1 the default ASCII tables, as distributed in
914 pcre2_chartables.c.dist
915 2 a set of tables defining ISO 8859 characters
917 In table 2, some characters whose codes are greater than 128 are iden-
918 tified as letters, digits, spaces, etc. Setting alternate character
919 tables and a locale are mutually exclusive.
921 Setting certain match controls
923 The following modifiers are really subject modifiers, and are described
924 under "Subject Modifiers" below. However, they may be included in a
925 pattern's modifier list, in which case they are applied to every sub-
926 ject line that is processed with that pattern. These modifiers do not
927 affect the compilation process.
929 aftertext show text after match
930 allaftertext show text after captures
931 allcaptures show all captures
932 allusedtext show all consulted text
933 altglobal alternative global matching
934 /g global global matching
935 jitstack=<n> set size of JIT stack
936 mark show mark values
937 replace=<string> specify a replacement string
938 startchar show starting character when relevant
939 substitute_extended use PCRE2_SUBSTITUTE_EXTENDED
940 substitute_overflow_length use PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
941 substitute_unknown_unset use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
942 substitute_unset_empty use PCRE2_SUBSTITUTE_UNSET_EMPTY
944 These modifiers may not appear in a #pattern command. If you want them
945 as defaults, set them in a #subject command.
947 Specifying literal subject lines
949 If the subject_literal modifier is present on a pattern, all the sub-
950 ject lines that it matches are taken as literal strings, with no inter-
951 pretation of backslashes. It is not possible to set subject modifiers
952 on such lines, but any that are set as defaults by a #subject command
955 Saving a compiled pattern
957 When a pattern with the push modifier is successfully compiled, it is
958 pushed onto a stack of compiled patterns, and pcre2test expects the
959 next line to contain a new pattern (or a command) instead of a subject
960 line. This facility is used when saving compiled patterns to a file, as
961 described in the section entitled "Saving and restoring compiled pat-
962 terns" below. If pushcopy is used instead of push, a copy of the com-
963 piled pattern is stacked, leaving the original as current, ready to
964 match the following input lines. This provides a way of testing the
965 pcre2_code_copy() function. The push and pushcopy modifiers are
966 incompatible with compilation modifiers such as global that act at
967 match time. Any that are specified are ignored (for the stacked copy),
968 with a warning message, except for replace, which causes an error. Note
969 that jitverify, which is allowed, does not carry through to any subse-
970 quent matching that uses a stacked pattern.
972 Testing foreign pattern conversion
974 The experimental foreign pattern conversion functions in PCRE2 can be
975 tested by setting the convert modifier. Its argument is a colon-sepa-
976 rated list of options, which set the equivalent option for the
977 pcre2_pattern_convert() function:
979 glob PCRE2_CONVERT_GLOB
980 glob_no_starstar PCRE2_CONVERT_GLOB_NO_STARSTAR
981 glob_no_wild_separator PCRE2_CONVERT_GLOB_NO_WILD_SEPARATOR
982 posix_basic PCRE2_CONVERT_POSIX_BASIC
983 posix_extended PCRE2_CONVERT_POSIX_EXTENDED
984 unset Unset all options
986 The "unset" value is useful for turning off a default that has been set
987 by a #pattern command. When one of these options is set, the input pat-
988 tern is passed to pcre2_pattern_convert(). If the conversion is suc-
989 cessful, the result is reflected in the output and then passed to
990 pcre2_compile(). The normal utf and no_utf_check options, if set, cause
991 the PCRE2_CONVERT_UTF and PCRE2_CONVERT_NO_UTF_CHECK options to be
992 passed to pcre2_pattern_convert().
994 By default, the conversion function is allowed to allocate a buffer for
995 its output. However, if the convert_length modifier is set to a value
996 greater than zero, pcre2test passes a buffer of the given length. This
997 makes it possible to test the length check.
999 The convert_glob_escape and convert_glob_separator modifiers can be
1000 used to specify the escape and separator characters for glob process-
1001 ing, overriding the defaults, which are operating-system dependent.
1006 The modifiers that can appear in subject lines and the #subject command
1009 Setting match options
1011 The following modifiers set options for pcre2_match() or
1012 pcre2_dfa_match(). See pcreapi for a description of their effects.
1014 anchored set PCRE2_ANCHORED
1015 endanchored set PCRE2_ENDANCHORED
1016 dfa_restart set PCRE2_DFA_RESTART
1017 dfa_shortest set PCRE2_DFA_SHORTEST
1018 no_jit set PCRE2_NO_JIT
1019 no_utf_check set PCRE2_NO_UTF_CHECK
1020 notbol set PCRE2_NOTBOL
1021 notempty set PCRE2_NOTEMPTY
1022 notempty_atstart set PCRE2_NOTEMPTY_ATSTART
1023 noteol set PCRE2_NOTEOL
1024 partial_hard (or ph) set PCRE2_PARTIAL_HARD
1025 partial_soft (or ps) set PCRE2_PARTIAL_SOFT
1027 The partial matching modifiers are provided with abbreviations because
1028 they appear frequently in tests.
1030 If the posix or posix_nosub modifier was present on the pattern, caus-
1031 ing the POSIX wrapper API to be used, the only option-setting modifiers
1032 that have any effect are notbol, notempty, and noteol, causing REG_NOT-
1033 BOL, REG_NOTEMPTY, and REG_NOTEOL, respectively, to be passed to
1034 regexec(). The other modifiers are ignored, with a warning message.
1036 There is one additional modifier that can be used with the POSIX wrap-
1037 per. It is ignored (with a warning) if used for non-POSIX matching.
1039 posix_startend=<n>[:<m>]
1041 This causes the subject string to be passed to regexec() using the
1042 REG_STARTEND option, which uses offsets to specify which part of the
1043 string is searched. If only one number is given, the end offset is
1044 passed as the end of the subject string. For more detail of REG_STAR-
1045 TEND, see the pcre2posix documentation. If the subject string contains
1046 binary zeros (coded as escapes such as \x{00} because pcre2test does
1047 not support actual binary zeros in its input), you must use posix_star-
1048 tend to specify its length.
1050 Setting match controls
1052 The following modifiers affect the matching process or request addi-
1053 tional information. Some of them may also be specified on a pattern
1054 line (see above), in which case they apply to every subject line that
1055 is matched against that pattern.
1057 aftertext show text after match
1058 allaftertext show text after captures
1059 allcaptures show all captures
1060 allusedtext show all consulted text (non-JIT only)
1061 altglobal alternative global matching
1062 callout_capture show captures at callout time
1063 callout_data=<n> set a value to pass via callouts
1064 callout_error=<n>[:<m>] control callout error
1065 callout_extra show extra callout information
1066 callout_fail=<n>[:<m>] control callout failure
1067 callout_no_where do not show position of a callout
1068 callout_none do not supply a callout function
1069 copy=<number or name> copy captured substring
1070 depth_limit=<n> set a depth limit
1071 dfa use pcre2_dfa_match()
1072 find_limits find match and depth limits
1073 get=<number or name> extract captured substring
1074 getall extract all captured substrings
1075 /g global global matching
1076 heap_limit=<n> set a limit on heap memory (Kbytes)
1077 jitstack=<n> set size of JIT stack
1078 mark show mark values
1079 match_limit=<n> set a match limit
1080 memory show heap memory usage
1081 null_context match with a NULL context
1082 offset=<n> set starting offset
1083 offset_limit=<n> set offset limit
1084 ovector=<n> set size of output vector
1085 recursion_limit=<n> obsolete synonym for depth_limit
1086 replace=<string> specify a replacement string
1087 startchar show startchar when relevant
1088 startoffset=<n> same as offset=<n>
1089 substitute_extedded use PCRE2_SUBSTITUTE_EXTENDED
1090 substitute_overflow_length use PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
1091 substitute_unknown_unset use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
1092 substitute_unset_empty use PCRE2_SUBSTITUTE_UNSET_EMPTY
1093 zero_terminate pass the subject as zero-terminated
1095 The effects of these modifiers are described in the following sections.
1096 When matching via the POSIX wrapper API, the aftertext, allaftertext,
1097 and ovector subject modifiers work as described below. All other modi-
1098 fiers are either ignored, with a warning message, or cause an error.
1102 The aftertext modifier requests that as well as outputting the part of
1103 the subject string that matched the entire pattern, pcre2test should in
1104 addition output the remainder of the subject string. This is useful for
1105 tests where the subject contains multiple copies of the same substring.
1106 The allaftertext modifier requests the same action for captured sub-
1107 strings as well as the main matched substring. In each case the remain-
1108 der is output on the following line with a plus character following the
1111 The allusedtext modifier requests that all the text that was consulted
1112 during a successful pattern match by the interpreter should be shown.
1113 This feature is not supported for JIT matching, and if requested with
1114 JIT it is ignored (with a warning message). Setting this modifier
1115 affects the output if there is a lookbehind at the start of a match, or
1116 a lookahead at the end, or if \K is used in the pattern. Characters
1117 that precede or follow the start and end of the actual match are indi-
1118 cated in the output by '<' or '>' characters underneath them. Here is
1121 re> /(?<=pqr)abc(?=xyz)/
1122 data> 123pqrabcxyz456\=allusedtext
1126 This shows that the matched string is "abc", with the preceding and
1127 following strings "pqr" and "xyz" having been consulted during the
1128 match (when processing the assertions).
1130 The startchar modifier requests that the starting character for the
1131 match be indicated, if it is different to the start of the matched
1132 string. The only time when this occurs is when \K has been processed as
1133 part of the match. In this situation, the output for the matched string
1134 is displayed from the starting character instead of from the match
1135 point, with circumflex characters under the earlier characters. For
1139 data> abcxyz\=startchar
1143 Unlike allusedtext, the startchar modifier can be used with JIT. How-
1144 ever, these two modifiers are mutually exclusive.
1146 Showing the value of all capture groups
1148 The allcaptures modifier requests that the values of all potential cap-
1149 tured parentheses be output after a match. By default, only those up to
1150 the highest one actually used in the match are output (corresponding to
1151 the return code from pcre2_match()). Groups that did not take part in
1152 the match are output as "<unset>". This modifier is not relevant for
1153 DFA matching (which does no capturing); it is ignored, with a warning
1154 message, if present.
1158 A callout function is supplied when pcre2test calls the library match-
1159 ing functions, unless callout_none is specified. Its behaviour can be
1160 controlled by various modifiers listed above whose names begin with
1161 callout_. Details are given in the section entitled "Callouts" below.
1163 Finding all matches in a string
1165 Searching for all possible matches within a subject can be requested by
1166 the global or altglobal modifier. After finding a match, the matching
1167 function is called again to search the remainder of the subject. The
1168 difference between global and altglobal is that the former uses the
1169 start_offset argument to pcre2_match() or pcre2_dfa_match() to start
1170 searching at a new point within the entire string (which is what Perl
1171 does), whereas the latter passes over a shortened subject. This makes a
1172 difference to the matching process if the pattern begins with a lookbe-
1173 hind assertion (including \b or \B).
1175 If an empty string is matched, the next match is done with the
1176 PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED flags set, in order to search
1177 for another, non-empty, match at the same point in the subject. If this
1178 match fails, the start offset is advanced, and the normal match is
1179 retried. This imitates the way Perl handles such cases when using the
1180 /g modifier or the split() function. Normally, the start offset is
1181 advanced by one character, but if the newline convention recognizes
1182 CRLF as a newline, and the current character is CR followed by LF, an
1183 advance of two characters occurs.
1185 Testing substring extraction functions
1187 The copy and get modifiers can be used to test the pcre2_sub-
1188 string_copy_xxx() and pcre2_substring_get_xxx() functions. They can be
1189 given more than once, and each can specify a group name or number, for
1192 abcd\=copy=1,copy=3,get=G1
1194 If the #subject command is used to set default copy and/or get lists,
1195 these can be unset by specifying a negative number to cancel all num-
1196 bered groups and an empty name to cancel all named groups.
1198 The getall modifier tests pcre2_substring_list_get(), which extracts
1199 all captured substrings.
1201 If the subject line is successfully matched, the substrings extracted
1202 by the convenience functions are output with C, G, or L after the
1203 string number instead of a colon. This is in addition to the normal
1204 full list. The string length (that is, the return from the extraction
1205 function) is given in parentheses after each substring, followed by the
1206 name when the extraction was by name.
1208 Testing the substitution function
1210 If the replace modifier is set, the pcre2_substitute() function is
1211 called instead of one of the matching functions. Note that replacement
1212 strings cannot contain commas, because a comma signifies the end of a
1213 modifier. This is not thought to be an issue in a test program.
1215 Unlike subject strings, pcre2test does not process replacement strings
1216 for escape sequences. In UTF mode, a replacement string is checked to
1217 see if it is a valid UTF-8 string. If so, it is correctly converted to
1218 a UTF string of the appropriate code unit width. If it is not a valid
1219 UTF-8 string, the individual code units are copied directly. This pro-
1220 vides a means of passing an invalid UTF-8 string for testing purposes.
1222 The following modifiers set options (in additional to the normal match
1223 options) for pcre2_substitute():
1225 global PCRE2_SUBSTITUTE_GLOBAL
1226 substitute_extended PCRE2_SUBSTITUTE_EXTENDED
1227 substitute_overflow_length PCRE2_SUBSTITUTE_OVERFLOW_LENGTH
1228 substitute_unknown_unset PCRE2_SUBSTITUTE_UNKNOWN_UNSET
1229 substitute_unset_empty PCRE2_SUBSTITUTE_UNSET_EMPTY
1232 After a successful substitution, the modified string is output, pre-
1233 ceded by the number of replacements. This may be zero if there were no
1234 matches. Here is a simple example of a substitution test:
1242 Subject and replacement strings should be kept relatively short (fewer
1243 than 256 characters) for substitution tests, as fixed-size buffers are
1244 used. To make it easy to test for buffer overflow, if the replacement
1245 string starts with a number in square brackets, that number is passed
1246 to pcre2_substitute() as the size of the output buffer, with the
1247 replacement string starting at the next character. Here is an example
1248 that tests the edge case:
1251 123abc123\=replace=[10]XYZ
1253 123abc123\=replace=[9]XYZ
1254 Failed: error -47: no more memory
1256 The default action of pcre2_substitute() is to return
1257 PCRE2_ERROR_NOMEMORY when the output buffer is too small. However, if
1258 the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set (by using the sub-
1259 stitute_overflow_length modifier), pcre2_substitute() continues to go
1260 through the motions of matching and substituting, in order to compute
1261 the size of buffer that is required. When this happens, pcre2test shows
1262 the required buffer length (which includes space for the trailing zero)
1263 as part of the error message. For example:
1265 /abc/substitute_overflow_length
1266 123abc123\=replace=[9]XYZ
1267 Failed: error -47: no more memory: 10 code units are needed
1269 A replacement string is ignored with POSIX and DFA matching. Specifying
1270 partial matching provokes an error return ("bad option value") from
1273 Setting the JIT stack size
1275 The jitstack modifier provides a way of setting the maximum stack size
1276 that is used by the just-in-time optimization code. It is ignored if
1277 JIT optimization is not being used. The value is a number of kibibytes
1278 (units of 1024 bytes). Setting zero reverts to the default of 32KiB.
1279 Providing a stack that is larger than the default is necessary only for
1280 very complicated patterns. If jitstack is set non-zero on a subject
1281 line it overrides any value that was set on the pattern.
1283 Setting heap, match, and depth limits
1285 The heap_limit, match_limit, and depth_limit modifiers set the appro-
1286 priate limits in the match context. These values are ignored when the
1287 find_limits modifier is specified.
1289 Finding minimum limits
1291 If the find_limits modifier is present on a subject line, pcre2test
1292 calls the relevant matching function several times, setting different
1293 values in the match context via pcre2_set_heap_limit(),
1294 pcre2_set_match_limit(), or pcre2_set_depth_limit() until it finds the
1295 minimum values for each parameter that allows the match to complete
1296 without error. If JIT is being used, only the match limit is relevant.
1298 When using this modifier, the pattern should not contain any limit set-
1299 tings such as (*LIMIT_MATCH=...) within it. If such a setting is
1300 present and is lower than the minimum matching value, the minimum value
1301 cannot be found because pcre2_set_match_limit() etc. are only able to
1302 reduce the value of an in-pattern limit; they cannot increase it.
1304 For non-DFA matching, the minimum depth_limit number is a measure of
1305 how much nested backtracking happens (that is, how deeply the pattern's
1306 tree is searched). In the case of DFA matching, depth_limit controls
1307 the depth of recursive calls of the internal function that is used for
1308 handling pattern recursion, lookaround assertions, and atomic groups.
1310 For non-DFA matching, the match_limit number is a measure of the amount
1311 of backtracking that takes place, and learning the minimum value can be
1312 instructive. For most simple matches, the number is quite small, but
1313 for patterns with very large numbers of matching possibilities, it can
1314 become large very quickly with increasing length of subject string. In
1315 the case of DFA matching, match_limit controls the total number of
1316 calls, both recursive and non-recursive, to the internal matching func-
1317 tion, thus controlling the overall amount of computing resource that is
1320 For both kinds of matching, the heap_limit number, which is in
1321 kibibytes (units of 1024 bytes), limits the amount of heap memory used
1322 for matching. A value of zero disables the use of any heap memory; many
1323 simple pattern matches can be done without using the heap, so zero is
1324 not an unreasonable setting.
1329 The mark modifier causes the names from backtracking control verbs that
1330 are returned from calls to pcre2_match() to be displayed. If a mark is
1331 returned for a match, non-match, or partial match, pcre2test shows it.
1332 For a match, it is on a line by itself, tagged with "MK:". Otherwise,
1333 it is added to the non-match message.
1335 Showing memory usage
1337 The memory modifier causes pcre2test to log the sizes of all heap mem-
1338 ory allocation and freeing calls that occur during a call to
1339 pcre2_match() or pcre2_dfa_match(). These occur only when a match
1340 requires a bigger vector than the default for remembering backtracking
1341 points (pcre2_match()) or for internal workspace (pcre2_dfa_match()).
1342 In many cases there will be no heap memory used and therefore no addi-
1343 tional output. No heap memory is allocated during matching with JIT, so
1344 in that case the memory modifier never has any effect. For this modi-
1345 fier to work, the null_context modifier must not be set on both the
1346 pattern and the subject, though it can be set on one or the other.
1348 Setting a starting offset
1350 The offset modifier sets an offset in the subject string at which
1351 matching starts. Its value is a number of code units, not characters.
1353 Setting an offset limit
1355 The offset_limit modifier sets a limit for unanchored matches. If a
1356 match cannot be found starting at or before this offset in the subject,
1357 a "no match" return is given. The data value is a number of code units,
1358 not characters. When this modifier is used, the use_offset_limit modi-
1359 fier must have been set for the pattern; if not, an error is generated.
1361 Setting the size of the output vector
1363 The ovector modifier applies only to the subject line in which it
1364 appears, though of course it can also be used to set a default in a
1365 #subject command. It specifies the number of pairs of offsets that are
1366 available for storing matching information. The default is 15.
1368 A value of zero is useful when testing the POSIX API because it causes
1369 regexec() to be called with a NULL capture vector. When not testing the
1370 POSIX API, a value of zero is used to cause pcre2_match_data_cre-
1371 ate_from_pattern() to be called, in order to create a match block of
1372 exactly the right size for the pattern. (It is not possible to create a
1373 match block with a zero-length ovector; there is always at least one
1376 Passing the subject as zero-terminated
1378 By default, the subject string is passed to a native API matching func-
1379 tion with its correct length. In order to test the facility for passing
1380 a zero-terminated string, the zero_terminate modifier is provided. It
1381 causes the length to be passed as PCRE2_ZERO_TERMINATED. When matching
1382 via the POSIX interface, this modifier is ignored, with a warning.
1384 When testing pcre2_substitute(), this modifier also has the effect of
1385 passing the replacement string as zero-terminated.
1387 Passing a NULL context
1389 Normally, pcre2test passes a context block to pcre2_match(),
1390 pcre2_dfa_match() or pcre2_jit_match(). If the null_context modifier is
1391 set, however, NULL is passed. This is for testing that the matching
1392 functions behave correctly in this case (they use default values). This
1393 modifier cannot be used with the find_limits modifier or when testing
1394 the substitution function.
1397 THE ALTERNATIVE MATCHING FUNCTION
1399 By default, pcre2test uses the standard PCRE2 matching function,
1400 pcre2_match() to match each subject line. PCRE2 also supports an alter-
1401 native matching function, pcre2_dfa_match(), which operates in a dif-
1402 ferent way, and has some restrictions. The differences between the two
1403 functions are described in the pcre2matching documentation.
1405 If the dfa modifier is set, the alternative matching function is used.
1406 This function finds all possible matches at a given point in the sub-
1407 ject. If, however, the dfa_shortest modifier is set, processing stops
1408 after the first match is found. This is always the shortest possible
1412 DEFAULT OUTPUT FROM pcre2test
1414 This section describes the output when the normal matching function,
1415 pcre2_match(), is being used.
1417 When a match succeeds, pcre2test outputs the list of captured sub-
1418 strings, starting with number 0 for the string that matched the whole
1419 pattern. Otherwise, it outputs "No match" when the return is
1420 PCRE2_ERROR_NOMATCH, or "Partial match:" followed by the partially
1421 matching substring when the return is PCRE2_ERROR_PARTIAL. (Note that
1422 this is the entire substring that was inspected during the partial
1423 match; it may include characters before the actual match start if a
1424 lookbehind assertion, \K, \b, or \B was involved.)
1426 For any other return, pcre2test outputs the PCRE2 negative error number
1427 and a short descriptive phrase. If the error is a failed UTF string
1428 check, the code unit offset of the start of the failing character is
1429 also output. Here is an example of an interactive pcre2test run.
1432 PCRE2 version 10.22 2016-07-29
1441 Unset capturing substrings that are not followed by one that is set are
1442 not shown by pcre2test unless the allcaptures modifier is specified. In
1443 the following example, there are two capturing substrings, but when the
1444 first data line is matched, the second, unset substring is not shown.
1445 An "internal" unset substring is shown as "<unset>", as for the second
1457 If the strings contain any non-printing characters, they are output as
1458 \xhh escapes if the value is less than 256 and UTF mode is not set.
1459 Otherwise they are output as \x{hh...} escapes. See below for the defi-
1460 nition of non-printing characters. If the aftertext modifier is set,
1461 the output for substring 0 is followed by the the rest of the subject
1462 string, identified by "0+" like this:
1469 If global matching is requested, the results of successive matching
1470 attempts are output in sequence, like this:
1481 "No match" is output only if the first match attempt fails. Here is an
1482 example of a failure message (the offset 4 that is specified by the
1483 offset modifier is past the end of the subject string):
1487 Error -24 (bad offset value)
1489 Note that whereas patterns can be continued over several lines (a plain
1490 ">" prompt is used for continuations), subject lines may not. However
1491 newlines can be included in a subject by means of the \n escape (or \r,
1492 \r\n, etc., depending on the newline sequence setting).
1495 OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
1497 When the alternative matching function, pcre2_dfa_match(), is used, the
1498 output consists of a list of all the matches that start at the first
1499 point in the subject where there is at least one match. For example:
1501 re> /(tang|tangerine|tan)/
1502 data> yellow tangerine\=dfa
1507 Using the normal matching function on this data finds only "tang". The
1508 longest matching string is always given first (and numbered zero).
1509 After a PCRE2_ERROR_PARTIAL return, the output is "Partial match:",
1510 followed by the partially matching substring. Note that this is the
1511 entire substring that was inspected during the partial match; it may
1512 include characters before the actual match start if a lookbehind asser-
1513 tion, \b, or \B was involved. (\K is not supported for DFA matching.)
1515 If global matching is requested, the search for further matches resumes
1516 at the end of the longest match. For example:
1518 re> /(tang|tangerine|tan)/g
1519 data> yellow tangerine and tangy sultana\=dfa
1527 The alternative matching function does not support substring capture,
1528 so the modifiers that are concerned with captured substrings are not
1532 RESTARTING AFTER A PARTIAL MATCH
1534 When the alternative matching function has given the PCRE2_ERROR_PAR-
1535 TIAL return, indicating that the subject partially matched the pattern,
1536 you can restart the match with additional subject data by means of the
1537 dfa_restart modifier. For example:
1539 re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
1542 data> n05\=dfa,dfa_restart
1545 For further information about partial matching, see the pcre2partial
1551 If the pattern contains any callout requests, pcre2test's callout func-
1552 tion is called during matching unless callout_none is specified. This
1553 works with both matching functions, and with JIT, though there are some
1554 differences in behaviour. The output for callouts with numerical argu-
1555 ments and those with string arguments is slightly different.
1557 Callouts with numerical arguments
1559 By default, the callout function displays the callout number, the start
1560 and current positions in the subject text at the callout time, and the
1561 next pattern item to be tested. For example:
1566 This output indicates that callout number 0 occurred for a match
1567 attempt starting at the fourth character of the subject string, when
1568 the pointer was at the seventh character, and when the next pattern
1569 item was \d. Just one circumflex is output if the start and current
1570 positions are the same, or if the current position precedes the start
1571 position, which can happen if the callout is in a lookbehind assertion.
1573 Callouts numbered 255 are assumed to be automatic callouts, inserted as
1574 a result of the auto_callout pattern modifier. In this case, instead of
1575 showing the callout number, the offset in the pattern, preceded by a
1576 plus, is output. For example:
1578 re> /\d?[A-E]\*/auto_callout
1587 If a pattern contains (*MARK) items, an additional line is output when-
1588 ever a change of latest mark is passed to the callout function. For
1591 re> /a(*MARK:X)bc/auto_callout
1602 The mark changes between matching "a" and "b", but stays the same for
1603 the rest of the match, so nothing more is output. If, as a result of
1604 backtracking, the mark reverts to being unset, the text "<unset>" is
1607 Callouts with string arguments
1609 The output for a callout with a string argument is similar, except that
1610 instead of outputting a callout number before the position indicators,
1611 the callout string and its offset in the pattern string are output
1612 before the reflection of the subject string, and the subject string is
1613 reflected for each callout. For example:
1615 re> /^ab(?C'first')cd(?C"second")ef/
1617 Callout (7): 'first'
1620 Callout (20): "second"
1628 The callout function in pcre2test returns zero (carry on matching) by
1629 default, but you can use a callout_fail modifier in a subject line to
1630 change this and other parameters of the callout (see below).
1632 If the callout_capture modifier is set, the current captured groups are
1633 output when a callout occurs. This is useful only for non-DFA matching,
1634 as pcre2_dfa_match() does not support capturing, so no captures are
1637 The normal callout output, showing the callout number or pattern offset
1638 (as described above) is suppressed if the callout_no_where modifier is
1641 When using the interpretive matching function pcre2_match() without
1642 JIT, setting the callout_extra modifier causes additional output from
1643 pcre2test's callout function to be generated. For the first callout in
1644 a match attempt at a new starting position in the subject, "New match
1645 attempt" is output. If there has been a backtrack since the last call-
1646 out (or start of matching if this is the first callout), "Backtrack" is
1647 output, followed by "No other matching paths" if the backtrack ended
1648 the previous match attempt. For example:
1650 re> /(a+)b/auto_callout,no_start_optimize,no_auto_possess
1651 data> aac\=callout_extra
1663 No other matching paths
1671 No other matching paths
1677 No other matching paths
1684 Notice that various optimizations must be turned off if you want all
1685 possible matching paths to be scanned. If no_start_optimize is not
1686 used, there is an immediate "no match", without any callouts, because
1687 the starting optimization fails to find "b" in the subject, which it
1688 knows must be present for any match. If no_auto_possess is not used,
1689 the "a+" item is turned into "a++", which reduces the number of back-
1692 The callout_extra modifier has no effect if used with the DFA matching
1693 function, or with JIT.
1695 Return values from callouts
1697 The default return from the callout function is zero, which allows
1698 matching to continue. The callout_fail modifier can be given one or two
1699 numbers. If there is only one number, 1 is returned instead of 0 (caus-
1700 ing matching to backtrack) when a callout of that number is reached. If
1701 two numbers (<n>:<m>) are given, 1 is returned when callout <n> is
1702 reached and there have been at least <m> callouts. The callout_error
1703 modifier is similar, except that PCRE2_ERROR_CALLOUT is returned, caus-
1704 ing the entire matching process to be aborted. If both these modifiers
1705 are set for the same callout number, callout_error takes precedence.
1706 Note that callouts with string arguments are always given the number
1709 The callout_data modifier can be given an unsigned or a negative num-
1710 ber. This is set as the "user data" that is passed to the matching
1711 function, and passed back when the callout function is invoked. Any
1712 value other than zero is used as a return from pcre2test's callout
1715 Inserting callouts can be helpful when using pcre2test to check compli-
1716 cated regular expressions. For further information about callouts, see
1717 the pcre2callout documentation.
1720 NON-PRINTING CHARACTERS
1722 When pcre2test is outputting text in the compiled version of a pattern,
1723 bytes other than 32-126 are always treated as non-printing characters
1724 and are therefore shown as hex escapes.
1726 When pcre2test is outputting text that is a matched part of a subject
1727 string, it behaves in the same way, unless a different locale has been
1728 set for the pattern (using the locale modifier). In this case, the
1729 isprint() function is used to distinguish printing and non-printing
1733 SAVING AND RESTORING COMPILED PATTERNS
1735 It is possible to save compiled patterns on disc or elsewhere, and
1736 reload them later, subject to a number of restrictions. JIT data cannot
1737 be saved. The host on which the patterns are reloaded must be running
1738 the same version of PCRE2, with the same code unit width, and must also
1739 have the same endianness, pointer width and PCRE2_SIZE type. Before
1740 compiled patterns can be saved they must be serialized, that is, con-
1741 verted to a stream of bytes. A single byte stream may contain any num-
1742 ber of compiled patterns, but they must all use the same character
1743 tables. A single copy of the tables is included in the byte stream (its
1744 size is 1088 bytes).
1746 The functions whose names begin with pcre2_serialize_ are used for
1747 serializing and de-serializing. They are described in the pcre2serial-
1748 ize documentation. In this section we describe the features of
1749 pcre2test that can be used to test these functions.
1751 Note that "serialization" in PCRE2 does not convert compiled patterns
1752 to an abstract format like Java or .NET. It just makes a reloadable
1753 byte code stream. Hence the restrictions on reloading mentioned above.
1755 In pcre2test, when a pattern with push modifier is successfully com-
1756 piled, it is pushed onto a stack of compiled patterns, and pcre2test
1757 expects the next line to contain a new pattern (or command) instead of
1758 a subject line. By contrast, the pushcopy modifier causes a copy of the
1759 compiled pattern to be stacked, leaving the original available for
1760 immediate matching. By using push and/or pushcopy, a number of patterns
1761 can be compiled and retained. These modifiers are incompatible with
1762 posix, and control modifiers that act at match time are ignored (with a
1763 message) for the stacked patterns. The jitverify modifier applies only
1770 causes all the stacked patterns to be serialized and the result written
1771 to the named file. Afterwards, all the stacked patterns are freed. The
1776 reads the data in the file, and then arranges for it to be de-serial-
1777 ized, with the resulting compiled patterns added to the pattern stack.
1778 The pattern on the top of the stack can be retrieved by the #pop com-
1779 mand, which must be followed by lines of subjects that are to be
1780 matched with the pattern, terminated as usual by an empty line or end
1781 of file. This command may be followed by a modifier list containing
1782 only control modifiers that act after a pattern has been compiled. In
1783 particular, hex, posix, posix_nosub, push, and pushcopy are not
1784 allowed, nor are any option-setting modifiers. The JIT modifiers are,
1785 however permitted. Here is an example that saves and reloads two pat-
1798 If jitverify is used with #pop, it does not automatically imply jit,
1799 which is different behaviour from when it is used on a pattern.
1801 The #popcopy command is analagous to the pushcopy modifier in that it
1802 makes current a copy of the topmost stack pattern, leaving the original
1808 pcre2(3), pcre2api(3), pcre2callout(3), pcre2jit, pcre2matching(3),
1809 pcre2partial(d), pcre2pattern(3), pcre2serialize(3).
1815 University Computing Service
1821 Last updated: 21 July 2018
1822 Copyright (c) 1997-2018 University of Cambridge.