/[pcre]/code/trunk/doc/pcretest.txt
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revision 75 by nigel, Sat Feb 24 21:40:37 2007 UTC revision 461 by ph10, Mon Oct 5 10:59:35 2009 UTC
# Line 1  Line 1 
1  PCRETEST(1)                                                        PCRETEST(1)  PCRETEST(1)                                                        PCRETEST(1)
2    
3    
   
4  NAME  NAME
5         pcretest - a program for testing Perl-compatible regular expressions.         pcretest - a program for testing Perl-compatible regular expressions.
6    
7    
8  SYNOPSIS  SYNOPSIS
9    
10         pcretest [-C] [-d] [-i] [-m] [-o osize] [-p] [-t] [source]         pcretest [options] [source] [destination]
             [destination]  
11    
12         pcretest  was written as a test program for the PCRE regular expression         pcretest  was written as a test program for the PCRE regular expression
13         library itself, but it can also be used for experimenting with  regular         library itself, but it can also be used for experimenting with  regular
# Line 20  SYNOPSIS Line 19  SYNOPSIS
19    
20  OPTIONS  OPTIONS
21    
22           -b        Behave as if each regex has the /B (show bytecode)  modifier;
23                     the internal form is output after compilation.
24    
25         -C        Output the version number of the PCRE library, and all avail-         -C        Output the version number of the PCRE library, and all avail-
26                   able   information  about  the  optional  features  that  are                   able  information  about  the  optional  features  that   are
27                   included, and then exit.                   included, and then exit.
28    
29         -d        Behave as if each regex had  the  /D  (debug)  modifier;  the         -d        Behave  as  if  each  regex  has the /D (debug) modifier; the
30                   internal form is output after compilation.                   internal form and information about the compiled  pattern  is
31                     output after compilation; -d is equivalent to -b -i.
32    
33           -dfa      Behave  as if each data line contains the \D escape sequence;
34                     this    causes    the    alternative    matching    function,
35                     pcre_dfa_exec(),   to   be   used  instead  of  the  standard
36                     pcre_exec() function (more detail is given below).
37    
38           -help     Output a brief summary these options and then exit.
39    
40         -i        Behave  as  if  each  regex  had the /I modifier; information         -i        Behave as if each regex  has  the  /I  modifier;  information
41                   about the compiled pattern is given after compilation.                   about the compiled pattern is given after compilation.
42    
43           -M        Behave  as if each data line contains the \M escape sequence;
44                     this causes PCRE to  discover  the  minimum  MATCH_LIMIT  and
45                     MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
46                     edly with different limits.
47    
48         -m        Output the size of each compiled pattern after  it  has  been         -m        Output the size of each compiled pattern after  it  has  been
49                   compiled.  This  is  equivalent  to adding /M to each regular                   compiled.  This  is  equivalent  to adding /M to each regular
50                   expression.  For  compatibility  with  earlier  versions   of                   expression.  For  compatibility  with  earlier  versions   of
51                   pcretest, -s is a synonym for -m.                   pcretest, -s is a synonym for -m.
52    
53         -o osize  Set  the number of elements in the output vector that is used         -o osize  Set  the number of elements in the output vector that is used
54                   when calling pcre_exec() to be osize. The  default  value  is                   when calling pcre_exec() or pcre_dfa_exec() to be osize.  The
55                   45, which is enough for 14 capturing subexpressions. The vec-                   default  value is 45, which is enough for 14 capturing subex-
56                   tor size can be changed  for  individual  matching  calls  by                   pressions  for  pcre_exec()  or  22  different  matches   for
57                   including \O in the data line (see below).                   pcre_dfa_exec().  The vector size can be changed for individ-
58                     ual matching calls by including \O  in  the  data  line  (see
59         -p        Behave  as  if  each regex has /P modifier; the POSIX wrapper                   below).
60                   API is used to call PCRE. None of the other options  has  any  
61                   effect when -p is set.         -p        Behave  as if each regex has the /P modifier; the POSIX wrap-
62                     per API is used to call PCRE. None of the other  options  has
63                     any effect when -p is set.
64    
65           -q        Do  not output the version number of pcretest at the start of
66                     execution.
67    
68           -S size   On Unix-like systems, set the size of the  runtime  stack  to
69                     size megabytes.
70    
71         -t        Run  each  compile, study, and match many times with a timer,         -t        Run  each  compile, study, and match many times with a timer,
72                   and output resulting time per compile or match (in  millisec-                   and output resulting time per compile or match (in  millisec-
73                   onds).  Do  not set -m with -t, because you will then get the                   onds).  Do  not set -m with -t, because you will then get the
74                   size output a zillion times, and  the  timing  will  be  dis-                   size output a zillion times, and  the  timing  will  be  dis-
75                   torted.                   torted.  You  can  control  the number of iterations that are
76                     used for timing by following -t with a number (as a  separate
77                     item on the command line). For example, "-t 1000" would iter-
78                     ate 1000 times. The default is to iterate 500000 times.
79    
80           -tm       This is like -t except that it times only the matching phase,
81                     not the compile or study phases.
82    
83    
84  DESCRIPTION  DESCRIPTION
# Line 61  DESCRIPTION Line 90  DESCRIPTION
90         "re>" to prompt for regular expressions, and "data>" to prompt for data         "re>" to prompt for regular expressions, and "data>" to prompt for data
91         lines.         lines.
92    
93           When pcretest is built, a configuration  option  can  specify  that  it
94           should  be  linked  with the libreadline library. When this is done, if
95           the input is from a terminal, it is read using the readline() function.
96           This  provides line-editing and history facilities. The output from the
97           -help option states whether or not readline() will be used.
98    
99         The program handles any number of sets of input on a single input file.         The program handles any number of sets of input on a single input file.
100         Each  set starts with a regular expression, and continues with any num-         Each  set starts with a regular expression, and continues with any num-
101         ber of data lines to be matched against the pattern.         ber of data lines to be matched against the pattern.
102    
103         Each data line is matched separately and independently. If you want  to         Each data line is matched separately and independently. If you want  to
104         do  multiple-line  matches, you have to use the \n escape sequence in a         do multi-line matches, you have to use the \n escape sequence (or \r or
105         single line of input to encode  the  newline  characters.  The  maximum         \r\n, etc., depending on the newline setting) in a single line of input
106         length of data line is 30,000 characters.         to  encode  the  newline  sequences. There is no limit on the length of
107           data lines; the input buffer is automatically extended  if  it  is  too
108           small.
109    
110         An  empty  line signals the end of the data lines, at which point a new         An  empty  line signals the end of the data lines, at which point a new
111         regular expression is read. The regular expressions are given  enclosed         regular expression is read. The regular expressions are given  enclosed
112         in any non-alphanumeric delimiters other than backslash, for example         in any non-alphanumeric delimiters other than backslash, for example:
113    
114           /(a|bc)x+yz/           /(a|bc)x+yz/
115    
# Line 120  PATTERN MODIFIERS Line 157  PATTERN MODIFIERS
157         The following table shows additional modifiers for setting PCRE options         The following table shows additional modifiers for setting PCRE options
158         that do not correspond to anything in Perl:         that do not correspond to anything in Perl:
159    
160           /A    PCRE_ANCHORED           /A              PCRE_ANCHORED
161           /C    PCRE_AUTO_CALLOUT           /C              PCRE_AUTO_CALLOUT
162           /E    PCRE_DOLLAR_ENDONLY           /E              PCRE_DOLLAR_ENDONLY
163           /N    PCRE_NO_AUTO_CAPTURE           /f              PCRE_FIRSTLINE
164           /U    PCRE_UNGREEDY           /J              PCRE_DUPNAMES
165           /X    PCRE_EXTRA           /N              PCRE_NO_AUTO_CAPTURE
166             /U              PCRE_UNGREEDY
167             /X              PCRE_EXTRA
168             /<JS>           PCRE_JAVASCRIPT_COMPAT
169             /<cr>           PCRE_NEWLINE_CR
170             /<lf>           PCRE_NEWLINE_LF
171             /<crlf>         PCRE_NEWLINE_CRLF
172             /<anycrlf>      PCRE_NEWLINE_ANYCRLF
173             /<any>          PCRE_NEWLINE_ANY
174             /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
175             /<bsr_unicode>  PCRE_BSR_UNICODE
176    
177           Those specifying line ending sequences are literal  strings  as  shown,
178           but  the  letters  can  be  in either case. This example sets multiline
179           matching with CRLF as the line ending sequence:
180    
181             /^abc/m<crlf>
182    
183           Details of the meanings of these PCRE options are given in the  pcreapi
184           documentation.
185    
186         Searching for all possible matches within each subject  string  can  be     Finding all matches in a string
187         requested  by  the  /g  or  /G modifier. After finding a match, PCRE is  
188           Searching  for  all  possible matches within each subject string can be
189           requested by the /g or /G modifier. After  finding  a  match,  PCRE  is
190         called again to search the remainder of the subject string. The differ-         called again to search the remainder of the subject string. The differ-
191         ence between /g and /G is that the former uses the startoffset argument         ence between /g and /G is that the former uses the startoffset argument
192         to pcre_exec() to start searching at a  new  point  within  the  entire         to  pcre_exec()  to  start  searching  at a new point within the entire
193         string  (which  is in effect what Perl does), whereas the latter passes         string (which is in effect what Perl does), whereas the  latter  passes
194         over a shortened substring. This makes a  difference  to  the  matching         over  a  shortened  substring.  This makes a difference to the matching
195         process if the pattern begins with a lookbehind assertion (including \b         process if the pattern begins with a lookbehind assertion (including \b
196         or \B).         or \B).
197    
198         If any call to pcre_exec() in a /g or  /G  sequence  matches  an  empty         If  any  call  to  pcre_exec()  in a /g or /G sequence matches an empty
199         string,  the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED         string, the next  call  is  done  with  the  PCRE_NOTEMPTY_ATSTART  and
200         flags set in order to search for another, non-empty, match at the  same         PCRE_ANCHORED  flags  set  in  order  to search for another, non-empty,
201         point.   If  this  second  match fails, the start offset is advanced by         match at the same point. If this second match fails, the  start  offset
202         one, and the normal match is retried. This imitates the way  Perl  han-         is  advanced  by  one  character, and the normal match is retried. This
203         dles such cases when using the /g modifier or the split() function.         imitates the way Perl handles such cases when using the /g modifier  or
204           the split() function.
205    
206       Other modifiers
207    
208         There are yet more modifiers for controlling the way pcretest operates.         There are yet more modifiers for controlling the way pcretest operates.
209    
210         The /+ modifier requests that as well as outputting the substring  that         The  /+ modifier requests that as well as outputting the substring that
211         matched  the  entire  pattern,  pcretest  should in addition output the         matched the entire pattern, pcretest  should  in  addition  output  the
212         remainder of the subject string. This is useful  for  tests  where  the         remainder  of  the  subject  string. This is useful for tests where the
213         subject contains multiple copies of the same substring.         subject contains multiple copies of the same substring.
214    
215           The /B modifier is a debugging feature. It requests that pcretest  out-
216           put  a representation of the compiled byte code after compilation. Nor-
217           mally this information contains length and offset values;  however,  if
218           /Z  is also present, this data is replaced by spaces. This is a special
219           feature for use in the automatic test scripts; it ensures that the same
220           output is generated for different internal link sizes.
221    
222         The  /L modifier must be followed directly by the name of a locale, for         The  /L modifier must be followed directly by the name of a locale, for
223         example,         example,
224    
# Line 169  PATTERN MODIFIERS Line 237  PATTERN MODIFIERS
237         pattern. If the pattern is studied, the results of that are  also  out-         pattern. If the pattern is studied, the results of that are  also  out-
238         put.         put.
239    
240         The /D modifier is a PCRE debugging feature, which also assumes /I.  It         The  /D modifier is a PCRE debugging feature, and is equivalent to /BI,
241         causes the internal form of compiled regular expressions to  be  output         that is, both the /B and the /I modifiers.
        after compilation. If the pattern was studied, the information returned  
        is also output.  
242    
243         The /F modifier causes pcretest to flip the byte order of the fields in         The /F modifier causes pcretest to flip the byte order of the fields in
244         the  compiled  pattern  that  contain  2-byte  and 4-byte numbers. This         the  compiled  pattern  that  contain  2-byte  and 4-byte numbers. This
# Line 185  PATTERN MODIFIERS Line 251  PATTERN MODIFIERS
251         The /S modifier causes pcre_study() to be called after  the  expression         The /S modifier causes pcre_study() to be called after  the  expression
252         has been compiled, and the results used when the expression is matched.         has been compiled, and the results used when the expression is matched.
253    
254         The /M modifier causes the size of memory block used to hold  the  com-         The  /M  modifier causes the size of memory block used to hold the com-
255         piled pattern to be output.         piled pattern to be output.
256    
257         The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API         The /P modifier causes pcretest to call PCRE via the POSIX wrapper  API
258         rather than its native API. When this  is  done,  all  other  modifiers         rather  than  its  native  API.  When this is done, all other modifiers
259         except  /i,  /m, and /+ are ignored. REG_ICASE is set if /i is present,         except /i, /m, and /+ are ignored. REG_ICASE is set if /i  is  present,
260         and REG_NEWLINE is set if /m is present. The  wrapper  functions  force         and  REG_NEWLINE  is  set if /m is present. The wrapper functions force
261         PCRE_DOLLAR_ENDONLY  always, and PCRE_DOTALL unless REG_NEWLINE is set.         PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
262    
263         The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8  option         The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8  option
264         set.  This  turns on support for UTF-8 character handling in PCRE, pro-         set.  This  turns on support for UTF-8 character handling in PCRE, pro-
# Line 214  DATA LINES Line 280  DATA LINES
280         nary" regular expressions, you probably don't need any  of  these.  The         nary" regular expressions, you probably don't need any  of  these.  The
281         following escapes are recognized:         following escapes are recognized:
282    
283           \a         alarm (= BEL)           \a         alarm (BEL, \x07)
284           \b         backspace           \b         backspace (\x08)
285           \e         escape           \e         escape (\x27)
286           \f         formfeed           \f         formfeed (\x0c)
287           \n         newline           \n         newline (\x0a)
288           \r         carriage return           \qdd       set the PCRE_MATCH_LIMIT limit to dd
289           \t         tab                        (any number of digits)
290           \v         vertical tab           \r         carriage return (\x0d)
291             \t         tab (\x09)
292             \v         vertical tab (\x0b)
293           \nnn       octal character (up to 3 octal digits)           \nnn       octal character (up to 3 octal digits)
294           \xhh       hexadecimal character (up to 2 hex digits)           \xhh       hexadecimal character (up to 2 hex digits)
295           \x{hh...}  hexadecimal character, any number of digits           \x{hh...}  hexadecimal character, any number of digits
296                        in UTF-8 mode                        in UTF-8 mode
297           \A         pass the PCRE_ANCHORED option to pcre_exec()           \A         pass the PCRE_ANCHORED option to pcre_exec()
298                          or pcre_dfa_exec()
299           \B         pass the PCRE_NOTBOL option to pcre_exec()           \B         pass the PCRE_NOTBOL option to pcre_exec()
300                          or pcre_dfa_exec()
301           \Cdd       call pcre_copy_substring() for substring dd           \Cdd       call pcre_copy_substring() for substring dd
302                        after a successful match (number less than 32)                        after a successful match (number less than 32)
303           \Cname     call pcre_copy_named_substring() for substring           \Cname     call pcre_copy_named_substring() for substring
# Line 242  DATA LINES Line 312  DATA LINES
312                        reached for the nth time                        reached for the nth time
313           \C*n       pass the number n (may be negative) as callout           \C*n       pass the number n (may be negative) as callout
314                        data; this is used as the callout return value                        data; this is used as the callout return value
315             \D         use the pcre_dfa_exec() match function
316             \F         only shortest match for pcre_dfa_exec()
317           \Gdd       call pcre_get_substring() for substring dd           \Gdd       call pcre_get_substring() for substring dd
318                        after a successful match (number less than 32)                        after a successful match (number less than 32)
319           \Gname     call pcre_get_named_substring() for substring           \Gname     call pcre_get_named_substring() for substring
# Line 249  DATA LINES Line 321  DATA LINES
321                        ated by next non-alphanumeric character)                        ated by next non-alphanumeric character)
322           \L         call pcre_get_substringlist() after a           \L         call pcre_get_substringlist() after a
323                        successful match                        successful match
324           \M         discover the minimum MATCH_LIMIT setting           \M         discover the minimum MATCH_LIMIT and
325                          MATCH_LIMIT_RECURSION settings
326           \N         pass the PCRE_NOTEMPTY option to pcre_exec()           \N         pass the PCRE_NOTEMPTY option to pcre_exec()
327                          or pcre_dfa_exec(); if used twice, pass the
328                          PCRE_NOTEMPTY_ATSTART option
329           \Odd       set the size of the output vector passed to           \Odd       set the size of the output vector passed to
330                        pcre_exec() to dd (any number of digits)                        pcre_exec() to dd (any number of digits)
331           \P         pass the PCRE_PARTIAL option to pcre_exec()           \P         pass the PCRE_PARTIAL_SOFT option to pcre_exec()
332                          or pcre_dfa_exec(); if used twice, pass the
333                          PCRE_PARTIAL_HARD option
334             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
335                          (any number of digits)
336             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
337           \S         output details of memory get/free calls during matching           \S         output details of memory get/free calls during matching
338             \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
339                          or pcre_dfa_exec()
340           \Z         pass the PCRE_NOTEOL option to pcre_exec()           \Z         pass the PCRE_NOTEOL option to pcre_exec()
341                          or pcre_dfa_exec()
342           \?         pass the PCRE_NO_UTF8_CHECK option to           \?         pass the PCRE_NO_UTF8_CHECK option to
343                        pcre_exec()                        pcre_exec() or pcre_dfa_exec()
344           \>dd       start the match at offset dd (any number of digits);           \>dd       start the match at offset dd (any number of digits);
345                        this sets the startoffset argument for pcre_exec()                        this sets the startoffset argument for pcre_exec()
346                          or pcre_dfa_exec()
347             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
348                          or pcre_dfa_exec()
349             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
350                          or pcre_dfa_exec()
351             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
352                          or pcre_dfa_exec()
353             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
354                          or pcre_dfa_exec()
355             \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()
356                          or pcre_dfa_exec()
357    
358           The  escapes  that  specify  line ending sequences are literal strings,
359           exactly as shown. No more than one newline setting should be present in
360           any data line.
361    
362         A  backslash  followed by anything else just escapes the anything else.         A  backslash  followed by anything else just escapes the anything else.
363         If the very last character is a backslash, it is ignored. This gives  a         If the very last character is a backslash, it is ignored. This gives  a
# Line 267  DATA LINES Line 365  DATA LINES
365         nates the data input.         nates the data input.
366    
367         If \M is present, pcretest calls pcre_exec() several times,  with  dif-         If \M is present, pcretest calls pcre_exec() several times,  with  dif-
368         ferent  values  in  the match_limit field of the pcre_extra data struc-         ferent  values  in  the match_limit and match_limit_recursion fields of
369         ture, until it finds the minimum number that is needed for  pcre_exec()         the pcre_extra data structure, until it finds the minimum  numbers  for
370         to  complete.  This  number is a measure of the amount of recursion and         each parameter that allow pcre_exec() to complete. The match_limit num-
371         backtracking that takes place, and checking it out can be  instructive.         ber is a measure of the amount of backtracking that  takes  place,  and
372         For  most  simple  matches, the number is quite small, but for patterns         checking it out can be instructive. For most simple matches, the number
373         with very large numbers of matching possibilities, it can become  large         is quite small, but for patterns with very large  numbers  of  matching
374         very quickly with increasing length of subject string.         possibilities,  it can become large very quickly with increasing length
375           of subject string. The match_limit_recursion number is a measure of how
376           much  stack  (or,  if  PCRE is compiled with NO_RECURSE, how much heap)
377           memory is needed to complete the match attempt.
378    
379         When  \O  is  used, the value specified may be higher or lower than the         When \O is used, the value specified may be higher or  lower  than  the
380         size set by the -O command line option (or defaulted to 45); \O applies         size set by the -O command line option (or defaulted to 45); \O applies
381         only to the call of pcre_exec() for the line in which it appears.         only to the call of pcre_exec() for the line in which it appears.
382    
383         If  the /P modifier was present on the pattern, causing the POSIX wrap-         If the /P modifier was present on the pattern, causing the POSIX  wrap-
384         per API to be used, only \B and \Z have any effect, causing  REG_NOTBOL         per  API  to  be  used, the only option-setting sequences that have any
385         and REG_NOTEOL to be passed to regexec() respectively.         effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL,  respectively,
386           to be passed to regexec().
387    
388         The  use of \x{hh...} to represent UTF-8 characters is not dependent on         The  use of \x{hh...} to represent UTF-8 characters is not dependent on
389         the use of the /8 modifier on the pattern.  It  is  recognized  always.         the use of the /8 modifier on the pattern.  It  is  recognized  always.
390         There  may  be  any number of hexadecimal digits inside the braces. The         There  may  be  any number of hexadecimal digits inside the braces. The
391         result is from one to six bytes, encoded according to the UTF-8  rules.         result is from one to six bytes,  encoded  according  to  the  original
392           UTF-8  rules  of  RFC  2279.  This  allows for values in the range 0 to
393           0x7FFFFFFF. Note that not all of those are valid Unicode  code  points,
394           or  indeed  valid  UTF-8 characters according to the later rules in RFC
395           3629.
396    
397    
398    THE ALTERNATIVE MATCHING FUNCTION
399    
400           By  default,  pcretest  uses  the  standard  PCRE  matching   function,
401           pcre_exec() to match each data line. From release 6.0, PCRE supports an
402           alternative matching function, pcre_dfa_test(),  which  operates  in  a
403           different  way,  and has some restrictions. The differences between the
404           two functions are described in the pcrematching documentation.
405    
406           If a data line contains the \D escape sequence, or if the command  line
407           contains  the -dfa option, the alternative matching function is called.
408           This function finds all possible matches at a given point. If, however,
409           the  \F escape sequence is present in the data line, it stops after the
410           first match is found. This is always the shortest possible match.
411    
412  OUTPUT FROM PCRETEST  
413    DEFAULT OUTPUT FROM PCRETEST
414    
415           This section describes the output when the  normal  matching  function,
416           pcre_exec(), is being used.
417    
418         When a match succeeds, pcretest outputs the list of captured substrings         When a match succeeds, pcretest outputs the list of captured substrings
419         that pcre_exec() returns, starting with number 0 for  the  string  that         that pcre_exec() returns, starting with number 0 for  the  string  that
420         matched the whole pattern. Otherwise, it outputs "No match" or "Partial         matched  the  whole  pattern. Otherwise, it outputs "No match" when the
421         match" when pcre_exec() returns PCRE_ERROR_NOMATCH  or  PCRE_ERROR_PAR-         return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
422         TIAL,  respectively, and otherwise the PCRE negative error number. Here         tially  matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
423           For any other returns, it outputs the PCRE negative error number.  Here
424         is an example of an interactive pcretest run.         is an example of an interactive pcretest run.
425    
426           $ pcretest           $ pcretest
427           PCRE version 5.00 07-Sep-2004           PCRE version 7.0 30-Nov-2006
428    
429             re> /^abc(\d+)/             re> /^abc(\d+)/
430           data> abc123           data> abc123
# Line 308  OUTPUT FROM PCRETEST Line 433  OUTPUT FROM PCRETEST
433           data> xyz           data> xyz
434           No match           No match
435    
436           Note  that unset capturing substrings that are not followed by one that
437           is set are not returned by pcre_exec(), and are not shown by  pcretest.
438           In  the following example, there are two capturing substrings, but when
439           the first data line is matched, the  second,  unset  substring  is  not
440           shown.  An "internal" unset substring is shown as "<unset>", as for the
441           second data line.
442    
443               re> /(a)|(b)/
444             data> a
445              0: a
446              1: a
447             data> b
448              0: b
449              1: <unset>
450              2: b
451    
452         If the strings contain any non-printing characters, they are output  as         If the strings contain any non-printing characters, they are output  as
453         \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on         \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
454         the pattern. If the pattern has the /+ modifier, the  output  for  sub-         the pattern. See below for the definition of  non-printing  characters.
455         string  0 is followed by the the rest of the subject string, identified         If  the pattern has the /+ modifier, the output for substring 0 is fol-
456         by "0+" like this:         lowed by the the rest of the subject string, identified  by  "0+"  like
457           this:
458    
459             re> /cat/+             re> /cat/+
460           data> cataract           data> cataract
461            0: cat            0: cat
462            0+ aract            0+ aract
463    
464         If the pattern has the /g or /G modifier,  the  results  of  successive         If  the  pattern  has  the /g or /G modifier, the results of successive
465         matching attempts are output in sequence, like this:         matching attempts are output in sequence, like this:
466    
467             re> /\Bi(\w\w)/g             re> /\Bi(\w\w)/g
# Line 333  OUTPUT FROM PCRETEST Line 475  OUTPUT FROM PCRETEST
475    
476         "No match" is output only if the first match attempt fails.         "No match" is output only if the first match attempt fails.
477    
478         If  any  of the sequences \C, \G, or \L are present in a data line that         If any of the sequences \C, \G, or \L are present in a data  line  that
479         is successfully matched, the substrings extracted  by  the  convenience         is  successfully  matched,  the substrings extracted by the convenience
480         functions are output with C, G, or L after the string number instead of         functions are output with C, G, or L after the string number instead of
481         a colon. This is in addition to the normal full list. The string length         a colon. This is in addition to the normal full list. The string length
482         (that  is,  the return from the extraction function) is given in paren-         (that is, the return from the extraction function) is given  in  paren-
483         theses after each string for \C and \G.         theses after each string for \C and \G.
484    
485         Note that while patterns can be continued over several lines  (a  plain         Note that whereas patterns can be continued over several lines (a plain
486         ">" prompt is used for continuations), data lines may not. However new-         ">" prompt is used for continuations), data lines may not. However new-
487         lines can be included in data by means of the \n escape.         lines  can  be included in data by means of the \n escape (or \r, \r\n,
488           etc., depending on the newline sequence setting).
489    
490    
491    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
492    
493           When the alternative matching function, pcre_dfa_exec(),  is  used  (by
494           means  of  the \D escape sequence or the -dfa command line option), the
495           output consists of a list of all the matches that start  at  the  first
496           point in the subject where there is at least one match. For example:
497    
498               re> /(tang|tangerine|tan)/
499             data> yellow tangerine\D
500              0: tangerine
501              1: tang
502              2: tan
503    
504           (Using  the  normal  matching function on this data finds only "tang".)
505           The longest matching string is always given first (and numbered  zero).
506           After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
507           lowed by the partially matching substring.
508    
509           If /g is present on the pattern, the search for further matches resumes
510           at the end of the longest match. For example:
511    
512               re> /(tang|tangerine|tan)/g
513             data> yellow tangerine and tangy sultana\D
514              0: tangerine
515              1: tang
516              2: tan
517              0: tang
518              1: tan
519              0: tan
520    
521           Since  the  matching  function  does not support substring capture, the
522           escape sequences that are concerned with captured  substrings  are  not
523           relevant.
524    
525    
526    RESTARTING AFTER A PARTIAL MATCH
527    
528           When the alternative matching function has given the PCRE_ERROR_PARTIAL
529           return, indicating that the subject partially matched the pattern,  you
530           can  restart  the match with additional subject data by means of the \R
531           escape sequence. For example:
532    
533               re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
534             data> 23ja\P\D
535             Partial match: 23ja
536             data> n05\R\D
537              0: n05
538    
539           For further information about partial  matching,  see  the  pcrepartial
540           documentation.
541    
542    
543  CALLOUTS  CALLOUTS
544    
545         If the pattern contains any callout requests, pcretest's callout  func-         If  the pattern contains any callout requests, pcretest's callout func-
546         tion  is  called  during  matching. By default, it displays the callout         tion is called during matching. This works  with  both  matching  func-
547         number, the start and current positions in  the  text  at  the  callout         tions. By default, the called function displays the callout number, the
548         time, and the next pattern item to be tested. For example, the output         start and current positions in the text at the callout  time,  and  the
549           next pattern item to be tested. For example, the output
550    
551           --->pqrabcdef           --->pqrabcdef
552             0    ^  ^     \d             0    ^  ^     \d
# Line 376  CALLOUTS Line 572  CALLOUTS
572            0: E*            0: E*
573    
574         The callout function in pcretest returns zero (carry  on  matching)  by         The callout function in pcretest returns zero (carry  on  matching)  by
575         default, but you can use an \C item in a data line (as described above)         default,  but you can use a \C item in a data line (as described above)
576         to change this.         to change this.
577    
578         Inserting callouts can be helpful when using pcretest to check  compli-         Inserting callouts can be helpful when using pcretest to check  compli-
# Line 384  CALLOUTS Line 580  CALLOUTS
580         the pcrecallout documentation.         the pcrecallout documentation.
581    
582    
583    NON-PRINTING CHARACTERS
584    
585           When pcretest is outputting text in the compiled version of a  pattern,
586           bytes  other  than 32-126 are always treated as non-printing characters
587           are are therefore shown as hex escapes.
588    
589           When pcretest is outputting text that is a matched part  of  a  subject
590           string,  it behaves in the same way, unless a different locale has been
591           set for the  pattern  (using  the  /L  modifier).  In  this  case,  the
592           isprint() function to distinguish printing and non-printing characters.
593    
594    
595  SAVING AND RELOADING COMPILED PATTERNS  SAVING AND RELOADING COMPILED PATTERNS
596    
597         The facilities described in this section are  not  available  when  the         The  facilities  described  in  this section are not available when the
598         POSIX inteface to PCRE is being used, that is, when the /P pattern mod-         POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
599         ifier is specified.         ifier is specified.
600    
601         When the POSIX interface is not in use, you can cause pcretest to write         When the POSIX interface is not in use, you can cause pcretest to write
602         a  compiled  pattern to a file, by following the modifiers with > and a         a compiled pattern to a file, by following the modifiers with >  and  a
603         file name.  For example:         file name.  For example:
604    
605           /pattern/im >/some/file           /pattern/im >/some/file
606    
607         See the pcreprecompile documentation for a discussion about saving  and         See  the pcreprecompile documentation for a discussion about saving and
608         re-using compiled patterns.         re-using compiled patterns.
609    
610         The  data  that  is  written  is  binary. The first eight bytes are the         The data that is written is binary.  The  first  eight  bytes  are  the
611         length of the compiled pattern data  followed  by  the  length  of  the         length  of  the  compiled  pattern  data  followed by the length of the
612         optional  study  data,  each  written as four bytes in big-endian order         optional study data, each written as four  bytes  in  big-endian  order
613         (most significant byte first). If there is no study  data  (either  the         (most  significant  byte  first). If there is no study data (either the
614         pattern was not studied, or studying did not return any data), the sec-         pattern was not studied, or studying did not return any data), the sec-
615         ond length is zero. The lengths are followed by an exact  copy  of  the         ond  length  is  zero. The lengths are followed by an exact copy of the
616         compiled pattern. If there is additional study data, this follows imme-         compiled pattern. If there is additional study data, this follows imme-
617         diately after the compiled pattern. After writing  the  file,  pcretest         diately  after  the  compiled pattern. After writing the file, pcretest
618         expects to read a new pattern.         expects to read a new pattern.
619    
620         A saved pattern can be reloaded into pcretest by specifing < and a file         A saved pattern can be reloaded into pcretest by specifing < and a file
621         name instead of a pattern. The name of the file must not  contain  a  <         name  instead  of  a pattern. The name of the file must not contain a <
622         character,  as  otherwise pcretest will interpret the line as a pattern         character, as otherwise pcretest will interpret the line as  a  pattern
623         delimited by < characters.  For example:         delimited by < characters.  For example:
624    
625            re> </some/file            re> </some/file
626           Compiled regex loaded from /some/file           Compiled regex loaded from /some/file
627           No study data           No study data
628    
629         When the pattern has been loaded, pcretest proceeds to read data  lines         When  the pattern has been loaded, pcretest proceeds to read data lines
630         in the usual way.         in the usual way.
631    
632         You  can copy a file written by pcretest to a different host and reload         You can copy a file written by pcretest to a different host and  reload
633         it there, even if the new host has opposite endianness to  the  one  on         it  there,  even  if the new host has opposite endianness to the one on
634         which  the pattern was compiled. For example, you can compile on an i86         which the pattern was compiled. For example, you can compile on an  i86
635         machine and run on a SPARC machine.         machine and run on a SPARC machine.
636    
637         File names for saving and reloading can be absolute  or  relative,  but         File  names  for  saving and reloading can be absolute or relative, but
638         note  that the shell facility of expanding a file name that starts with         note that the shell facility of expanding a file name that starts  with
639         a tilde (~) is not available.         a tilde (~) is not available.
640    
641         The ability to save and reload files in pcretest is intended for  test-         The  ability to save and reload files in pcretest is intended for test-
642         ing  and experimentation. It is not intended for production use because         ing and experimentation. It is not intended for production use  because
643         only a single pattern can be written to a file. Furthermore,  there  is         only  a  single pattern can be written to a file. Furthermore, there is
644         no  facility  for  supplying  custom  character  tables  for use with a         no facility for supplying  custom  character  tables  for  use  with  a
645         reloaded pattern. If the original  pattern  was  compiled  with  custom         reloaded  pattern.  If  the  original  pattern was compiled with custom
646         tables,  an  attempt to match a subject string using a reloaded pattern         tables, an attempt to match a subject string using a  reloaded  pattern
647         is likely to cause pcretest to crash.  Finally, if you attempt to  load         is  likely to cause pcretest to crash.  Finally, if you attempt to load
648         a file that is not in the correct format, the result is undefined.         a file that is not in the correct format, the result is undefined.
649    
650    
651    SEE ALSO
652    
653           pcre(3), pcreapi(3), pcrecallout(3),  pcrematching(3),  pcrepartial(d),
654           pcrepattern(3), pcreprecompile(3).
655    
656    
657  AUTHOR  AUTHOR
658    
659         Philip Hazel <ph10@cam.ac.uk>         Philip Hazel
660         University Computing Service,         University Computing Service
661         Cambridge CB2 3QG, England.         Cambridge CB2 3QH, England.
662    
663    
664    REVISION
665    
666  Last updated: 10 September 2004         Last updated: 26 September 2009
667  Copyright (c) 1997-2004 University of Cambridge.         Copyright (c) 1997-2009 University of Cambridge.

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