/[pcre]/code/trunk/doc/pcretest.txt
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revision 73 by nigel, Sat Feb 24 21:40:30 2007 UTC revision 79 by nigel, Sat Feb 24 21:40:52 2007 UTC
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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         pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [source] [destination]  
10           pcretest [-C] [-d] [-dfa] [-i] [-m] [-o osize] [-p] [-t] [source]
11                [destination]
12    
13         pcretest  was written as a test program for the PCRE regular expression         pcretest  was written as a test program for the PCRE regular expression
14         library itself, but it can also be used for experimenting with  regular         library itself, but it can also be used for experimenting with  regular
15         expressions.  This document describes the features of the test program;         expressions.  This document describes the features of the test program;
16         for details of the regular expressions themselves, see the  pcrepattern         for details of the regular expressions themselves, see the  pcrepattern
17         documentation.  For  details  of  PCRE and its options, see the pcreapi         documentation. For details of the PCRE library function calls and their
18         documentation.         options, see the pcreapi documentation.
19    
20    
21  OPTIONS  OPTIONS
22    
   
23         -C        Output the version number of the PCRE library, and all avail-         -C        Output the version number of the PCRE library, and all avail-
24                   able   information  about  the  optional  features  that  are                   able   information  about  the  optional  features  that  are
25                   included, and then exit.                   included, and then exit.
26    
27         -d        Behave as if each regex had the /D modifier (see below);  the         -d        Behave as if each regex has  the  /D  (debug)  modifier;  the
28                   internal form is output after compilation.                   internal form is output after compilation.
29    
30         -i        Behave  as  if  each  regex  had the /I modifier; information         -dfa      Behave  as if each data line contains the \D escape sequence;
31                     this    causes    the    alternative    matching    function,
32                     pcre_dfa_exec(),   to   be   used  instead  of  the  standard
33                     pcre_exec() function (more detail is given below).
34    
35           -i        Behave as if each regex  has  the  /I  modifier;  information
36                   about the compiled pattern is given after compilation.                   about the compiled pattern is given after compilation.
37    
38         -m        Output the size of each compiled pattern after  it  has  been         -m        Output  the  size  of each compiled pattern after it has been
39                   compiled.  This  is  equivalent  to adding /M to each regular                   compiled. This is equivalent to adding  /M  to  each  regular
40                   expression.  For  compatibility  with  earlier  versions   of                   expression.   For  compatibility  with  earlier  versions  of
41                   pcretest, -s is a synonym for -m.                   pcretest, -s is a synonym for -m.
42    
43         -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
44                   when calling PCRE to be osize. The default value is 45, which                   when  calling  pcre_exec()  to be osize. The default value is
45                   is  enough  for  14 capturing subexpressions. The vector size                   45, which is enough for 14 capturing subexpressions. The vec-
46                   can be changed for individual matching calls by including  \O                   tor  size  can  be  changed  for individual matching calls by
47                   in the data line (see below).                   including \O in the data line (see below).
48    
49         -p        Behave  as  if  each regex has /P modifier; the POSIX wrapper         -p        Behave as if each regex has the /P modifier; the POSIX  wrap-
50                   API is used to call PCRE. None of the other options  has  any                   per  API  is used to call PCRE. None of the other options has
51                   effect when -p is set.                   any effect when -p is set.
52    
53         -t        Run  each  compile, study, and match many times with a timer,         -t        Run each compile, study, and match many times with  a  timer,
54                   and output resulting time per compile or match (in  millisec-                   and  output resulting time per compile or match (in millisec-
55                   onds).  Do  not set -t with -m, because you will then get the                   onds). Do not set -m with -t, because you will then  get  the
56                   size output 20000 times and the timing will be distorted.                   size  output  a  zillion  times,  and the timing will be dis-
57                     torted.
58    
59    
60  DESCRIPTION  DESCRIPTION
# Line 63  DESCRIPTION Line 70  DESCRIPTION
70         Each set starts with a regular expression, and continues with any  num-         Each set starts with a regular expression, and continues with any  num-
71         ber of data lines to be matched against the pattern.         ber of data lines to be matched against the pattern.
72    
73         Each  line  is  matched separately and independently. If you want to do         Each  data line is matched separately and independently. If you want to
74         multiple-line matches, you have to use the \n escape sequence in a sin-         do multiple-line matches, you have to use the \n escape sequence  in  a
75         gle  line of input to encode the newline characters. The maximum length         single  line  of  input  to  encode the newline characters. The maximum
76         of data line is 30,000 characters.         length of data line is 30,000 characters.
77    
78         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
79         regular  expression is read. The regular expressions are given enclosed         regular  expression is read. The regular expressions are given enclosed
80         in any non-alphameric delimiters other than backslash, for example         in any non-alphanumeric delimiters other than backslash, for example
81    
82           /(a|bc)x+yz/           /(a|bc)x+yz/
83    
# Line 82  DESCRIPTION Line 89  DESCRIPTION
89           /abc\/def/           /abc\/def/
90    
91         If  you  do  so, the escape and the delimiter form part of the pattern,         If  you  do  so, the escape and the delimiter form part of the pattern,
92         but since delimiters are always non-alphameric, this  does  not  affect         but since delimiters are always non-alphanumeric, this does not  affect
93         its  interpretation.   If the terminating delimiter is immediately fol-         its  interpretation.   If the terminating delimiter is immediately fol-
94         lowed by a backslash, for example,         lowed by a backslash, for example,
95    
# Line 101  DESCRIPTION Line 108  DESCRIPTION
108    
109  PATTERN MODIFIERS  PATTERN MODIFIERS
110    
111         The pattern may be followed by i, m, s, or x to set the  PCRE_CASELESS,         A pattern may be followed by any number of modifiers, which are  mostly
112         PCRE_MULTILINE,  PCRE_DOTALL,  or  PCRE_EXTENDED options, respectively.         single  characters.  Following  Perl usage, these are referred to below
113         For example:         as, for example, "the /i modifier", even though the  delimiter  of  the
114           pattern  need  not always be a slash, and no slash is used when writing
115           modifiers. Whitespace may appear between the  final  pattern  delimiter
116           and the first modifier, and between the modifiers themselves.
117    
118           The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
119           PCRE_DOTALL, or PCRE_EXTENDED  options,  respectively,  when  pcre_com-
120           pile()  is  called. These four modifier letters have the same effect as
121           they do in Perl. For example:
122    
123           /caseless/i           /caseless/i
124    
125         These modifier letters have the same effect as they do in  Perl.  There         The following table shows additional modifiers for setting PCRE options
126         are  others that set PCRE options that do not correspond to anything in         that do not correspond to anything in Perl:
127         Perl: /A, /E, /N, /U, and /X  set  PCRE_ANCHORED,  PCRE_DOLLAR_ENDONLY,  
128         PCRE_NO_AUTO_CAPTURE, PCRE_UNGREEDY, and PCRE_EXTRA respectively.           /A    PCRE_ANCHORED
129             /C    PCRE_AUTO_CALLOUT
130             /E    PCRE_DOLLAR_ENDONLY
131             /f    PCRE_FIRSTLINE
132             /N    PCRE_NO_AUTO_CAPTURE
133             /U    PCRE_UNGREEDY
134             /X    PCRE_EXTRA
135    
136         Searching  for  all  possible matches within each subject string can be         Searching  for  all  possible matches within each subject string can be
137         requested by the /g or /G modifier. After  finding  a  match,  PCRE  is         requested by the /g or /G modifier. After  finding  a  match,  PCRE  is
# Line 129  PATTERN MODIFIERS Line 150  PATTERN MODIFIERS
150         one,  and  the normal match is retried. This imitates the way Perl han-         one,  and  the normal match is retried. This imitates the way Perl han-
151         dles such cases when using the /g modifier or the split() function.         dles such cases when using the /g modifier or the split() function.
152    
153         There are a number of other modifiers for controlling the way  pcretest         There are yet more modifiers for controlling the way pcretest operates.
        operates.  
154    
155         The  /+ modifier requests that as well as outputting the substring that         The  /+ modifier requests that as well as outputting the substring that
156         matched the entire pattern, pcretest  should  in  addition  output  the         matched the entire pattern, pcretest  should  in  addition  output  the
# Line 140  PATTERN MODIFIERS Line 160  PATTERN MODIFIERS
160         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
161         example,         example,
162    
163           /pattern/Lfr           /pattern/Lfr_FR
164    
165         For  this reason, it must be the last modifier letter. The given locale         For this reason, it must be the last modifier. The given locale is set,
166         is set, pcre_maketables() is called to build a set of character  tables         pcre_maketables() is called to build a set of character tables for  the
167         for  the locale, and this is then passed to pcre_compile() when compil-         locale,  and  this  is then passed to pcre_compile() when compiling the
168         ing the regular expression. Without an /L modifier, NULL is  passed  as         regular expression. Without an /L  modifier,  NULL  is  passed  as  the
169         the tables pointer; that is, /L applies only to the expression on which         tables  pointer; that is, /L applies only to the expression on which it
170         it appears.         appears.
171    
172         The /I modifier requests that pcretest  output  information  about  the         The /I modifier requests that pcretest  output  information  about  the
173         compiled  expression (whether it is anchored, has a fixed first charac-         compiled  pattern (whether it is anchored, has a fixed first character,
174         ter, and so on). It does this by calling pcre_fullinfo() after  compil-         and so on). It does this by calling pcre_fullinfo() after  compiling  a
175         ing  an expression, and outputting the information it gets back. If the         pattern.  If  the pattern is studied, the results of that are also out-
176         pattern is studied, the results of that are also output.         put.
177    
178         The /D modifier is a PCRE debugging feature, which also assumes /I.  It         The /D modifier is a PCRE debugging feature, which also assumes /I.  It
179         causes  the  internal form of compiled regular expressions to be output         causes  the  internal form of compiled regular expressions to be output
180         after compilation. If the pattern was studied, the information returned         after compilation. If the pattern was studied, the information returned
181         is also output.         is also output.
182    
183           The /F modifier causes pcretest to flip the byte order of the fields in
184           the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This
185           facility  is  for testing the feature in PCRE that allows it to execute
186           patterns that were compiled on a host with a different endianness. This
187           feature  is  not  available  when  the POSIX interface to PCRE is being
188           used, that is, when the /P pattern modifier is specified. See also  the
189           section about saving and reloading compiled patterns below.
190    
191         The  /S  modifier causes pcre_study() to be called after the expression         The  /S  modifier causes pcre_study() to be called after the expression
192         has been compiled, and the results used when the expression is matched.         has been compiled, and the results used when the expression is matched.
193    
# Line 183  PATTERN MODIFIERS Line 211  PATTERN MODIFIERS
211         checking of the string for UTF-8 validity.         checking of the string for UTF-8 validity.
212    
213    
 CALLOUTS  
   
        If  the pattern contains any callout requests, pcretest's callout func-  
        tion will be called. By default, it displays the  callout  number,  and  
        the  start  and  current positions in the text at the callout time. For  
        example, the output  
   
          --->pqrabcdef  
            0    ^  ^  
   
        indicates that callout number 0 occurred for a match  attempt  starting  
        at  the fourth character of the subject string, when the pointer was at  
        the seventh character. The callout  function  returns  zero  (carry  on  
        matching) by default.  
   
        Inserting  callouts may be helpful when using pcretest to check compli-  
        cated regular expressions. For further information about callouts,  see  
        the pcrecallout documentation.  
   
        For  testing  the PCRE library, additional control of callout behaviour  
        is available via escape sequences in the data, as described in the fol-  
        lowing  section.  In  particular, it is possible to pass in a number as  
        callout data (the default is zero). If the callout function receives  a  
        non-zero number, it returns that value instead of zero.  
   
   
214  DATA LINES  DATA LINES
215    
216         Before  each  data  line is passed to pcre_exec(), leading and trailing         Before  each  data  line is passed to pcre_exec(), leading and trailing
# Line 233  DATA LINES Line 235  DATA LINES
235           \A         pass the PCRE_ANCHORED option to pcre_exec()           \A         pass the PCRE_ANCHORED option to pcre_exec()
236           \B         pass the PCRE_NOTBOL option to pcre_exec()           \B         pass the PCRE_NOTBOL option to pcre_exec()
237           \Cdd       call pcre_copy_substring() for substring dd           \Cdd       call pcre_copy_substring() for substring dd
238                        after a successful match (any decimal number                        after a successful match (number less than 32)
                       less than 32)  
239           \Cname     call pcre_copy_named_substring() for substring           \Cname     call pcre_copy_named_substring() for substring
240                        "name" after a successful match (name termin-                        "name" after a successful match (name termin-
241                        ated by next non alphanumeric character)                        ated by next non alphanumeric character)
# Line 246  DATA LINES Line 247  DATA LINES
247           \C!n!m     return 1 instead of 0 when callout number n is           \C!n!m     return 1 instead of 0 when callout number n is
248                        reached for the nth time                        reached for the nth time
249           \C*n       pass the number n (may be negative) as callout           \C*n       pass the number n (may be negative) as callout
250                        data                        data; this is used as the callout return value
251             \D         use the pcre_dfa_exec() match function
252             \F         only shortest match for pcre_dfa_exec()
253           \Gdd       call pcre_get_substring() for substring dd           \Gdd       call pcre_get_substring() for substring dd
254                        after a successful match (any decimal number                        after a successful match (number less than 32)
                       less than 32)  
255           \Gname     call pcre_get_named_substring() for substring           \Gname     call pcre_get_named_substring() for substring
256                        "name" after a successful match (name termin-                        "name" after a successful match (name termin-
257                        ated by next non-alphanumeric character)                        ated by next non-alphanumeric character)
# Line 258  DATA LINES Line 260  DATA LINES
260           \M         discover the minimum MATCH_LIMIT setting           \M         discover the minimum MATCH_LIMIT setting
261           \N         pass the PCRE_NOTEMPTY option to pcre_exec()           \N         pass the PCRE_NOTEMPTY option to pcre_exec()
262           \Odd       set the size of the output vector passed to           \Odd       set the size of the output vector passed to
263                        pcre_exec() to dd (any number of decimal                        pcre_exec() to dd (any number of digits)
264                        digits)           \P         pass the PCRE_PARTIAL option to pcre_exec()
265                          or pcre_dfa_exec()
266             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
267           \S         output details of memory get/free calls during matching           \S         output details of memory get/free calls during matching
268           \Z         pass the PCRE_NOTEOL option to pcre_exec()           \Z         pass the PCRE_NOTEOL option to pcre_exec()
269           \?         pass the PCRE_NO_UTF8_CHECK option to           \?         pass the PCRE_NO_UTF8_CHECK option to
270                        pcre_exec()                        pcre_exec()
271             \>dd       start the match at offset dd (any number of digits);
272                          this sets the startoffset argument for pcre_exec()
273    
274         If \M is present, pcretest calls pcre_exec() several times,  with  dif-         A backslash followed by anything else just escapes the  anything  else.
275         ferent  values  in  the match_limit field of the pcre_extra data struc-         If  the very last character is a backslash, it is ignored. This gives a
276         ture, until it finds the minimum number that is needed for  pcre_exec()         way of passing an empty line as data, since a real  empty  line  termi-
        to  complete.  This  number is a measure of the amount of recursion and  
        backtracking that takes place, and checking it out can be  instructive.  
        For  most  simple  matches, the number is quite small, but for patterns  
        with very large numbers of matching possibilities, it can become  large  
        very quickly with increasing length of subject string.  
   
        When  \O is used, it may be higher or lower than the size set by the -O  
        option (or defaulted to 45); \O applies only to the call of pcre_exec()  
        for the line in which it appears.  
   
        A  backslash  followed by anything else just escapes the anything else.  
        If the very last character is a backslash, it is ignored. This gives  a  
        way  of  passing  an empty line as data, since a real empty line termi-  
277         nates the data input.         nates the data input.
278    
279         If /P was present on the regex, causing the POSIX  wrapper  API  to  be         If  \M  is present, pcretest calls pcre_exec() several times, with dif-
280         used,  only  0  causing  REG_NOTBOL  and  REG_NOTEOL  to  be  passed to         ferent values in the match_limit field of the  pcre_extra  data  struc-
281         regexec() respectively.         ture,  until it finds the minimum number that is needed for pcre_exec()
282           to complete. This number is a measure of the amount  of  recursion  and
283           backtracking  that takes place, and checking it out can be instructive.
284           For most simple matches, the number is quite small,  but  for  patterns
285           with  very large numbers of matching possibilities, it can become large
286           very quickly with increasing length of subject string.
287    
288           When \O is used, the value specified may be higher or  lower  than  the
289           size set by the -O command line option (or defaulted to 45); \O applies
290           only to the call of pcre_exec() for the line in which it appears.
291    
292           If the /P modifier was present on the pattern, causing the POSIX  wrap-
293           per  API to be used, only \B and \Z have any effect, causing REG_NOTBOL
294           and REG_NOTEOL to be passed to regexec() respectively.
295    
296         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
297         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.
# Line 293  DATA LINES Line 299  DATA LINES
299         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 UTF-8 rules.
300    
301    
302  OUTPUT FROM PCRETEST  THE ALTERNATIVE MATCHING FUNCTION
303    
304           By  default,  pcretest  uses  the  standard  PCRE  matching   function,
305           pcre_exec() to match each data line. From release 6.0, PCRE supports an
306           alternative matching function, pcre_dfa_test(),  which  operates  in  a
307           different  way,  and has some restrictions. The differences between the
308           two functions are described in the pcrematching documentation.
309    
310           If a data line contains the \D escape sequence, or if the command  line
311           contains  the -dfa option, the alternative matching function is called.
312           This function finds all possible matches at a given point. If, however,
313           the  \F escape sequence is present in the data line, it stops after the
314           first match is found. This is always the shortest possible match.
315    
316    
317    DEFAULT OUTPUT FROM PCRETEST
318    
319           This section describes the output when the  normal  matching  function,
320           pcre_exec(), is being used.
321    
322         When a match succeeds, pcretest outputs the list of captured substrings         When a match succeeds, pcretest outputs the list of captured substrings
323         that  pcre_exec()  returns,  starting with number 0 for the string that         that pcre_exec() returns, starting with number 0 for  the  string  that
324         matched the whole  pattern.  Here  is  an  example  of  an  interactive         matched the whole pattern. Otherwise, it outputs "No match" or "Partial
325         pcretest run.         match" when pcre_exec() returns PCRE_ERROR_NOMATCH  or  PCRE_ERROR_PAR-
326           TIAL,  respectively, and otherwise the PCRE negative error number. Here
327           is an example of an interactive pcretest run.
328    
329           $ pcretest           $ pcretest
330           PCRE version 4.00 08-Jan-2003           PCRE version 5.00 07-Sep-2004
331    
332             re> /^abc(\d+)/             re> /^abc(\d+)/
333           data> abc123           data> abc123
# Line 310  OUTPUT FROM PCRETEST Line 336  OUTPUT FROM PCRETEST
336           data> xyz           data> xyz
337           No match           No match
338    
339         If  the strings contain any non-printing characters, they are output as         If the strings contain any non-printing characters, they are output  as
340         \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
341         the  pattern.  If  the pattern has the /+ modifier, then the output for         the pattern. If the pattern has the /+ modifier, the  output  for  sub-
342         substring 0 is followed by the the rest of the subject string,  identi-         string  0 is followed by the the rest of the subject string, identified
343         fied by "0+" like this:         by "0+" like this:
344    
345             re> /cat/+             re> /cat/+
346           data> cataract           data> cataract
347            0: cat            0: cat
348            0+ aract            0+ aract
349    
350         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
351         matching attempts are output in sequence, like this:         matching attempts are output in sequence, like this:
352    
353             re> /\Bi(\w\w)/g             re> /\Bi(\w\w)/g
# Line 335  OUTPUT FROM PCRETEST Line 361  OUTPUT FROM PCRETEST
361    
362         "No match" is output only if the first match attempt fails.         "No match" is output only if the first match attempt fails.
363    
364         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
365         is  successfully  matched,  the substrings extracted by the convenience         is successfully matched, the substrings extracted  by  the  convenience
366         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
367         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
368         (that is, the return from the extraction function) is given  in  paren-         (that  is,  the return from the extraction function) is given in paren-
369         theses after each string for \C and \G.         theses after each string for \C and \G.
370    
371         Note  that  while patterns can be continued over several lines (a plain         Note that while patterns can be continued over several lines  (a  plain
372         ">" prompt is used for continuations), data lines may not. However new-         ">" prompt is used for continuations), data lines may not. However new-
373         lines can be included in data by means of the \n escape.         lines can be included in data by means of the \n escape.
374    
375    
376    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
377    
378           When the alternative matching function, pcre_dfa_exec(),  is  used  (by
379           means  of  the \D escape sequence or the -dfa command line option), the
380           output consists of a list of all the matches that start  at  the  first
381           point in the subject where there is at least one match. For example:
382    
383               re> /(tang|tangerine|tan)/
384             data> yellow tangerine\D
385              0: tangerine
386              1: tang
387              2: tan
388    
389           (Using  the  normal  matching function on this data finds only "tang".)
390           The longest matching string is always given first (and numbered  zero).
391    
392           If  /gP  is  present  on  the  pattern,  the search for further matches
393           resumes at the end of the longest match. For example:
394    
395               re> /(tang|tangerine|tan)/g
396             data> yellow tangerine and tangy sultana\D
397              0: tangerine
398              1: tang
399              2: tan
400              0: tang
401              1: tan
402              0: tan
403    
404           Since the matching function does not  support  substring  capture,  the
405           escape  sequences  that  are concerned with captured substrings are not
406           relevant.
407    
408    
409    RESTARTING AFTER A PARTIAL MATCH
410    
411           When the alternative matching function has given the PCRE_ERROR_PARTIAL
412           return,  indicating that the subject partially matched the pattern, you
413           can restart the match with additional subject data by means of  the  \R
414           escape sequence. For example:
415    
416               re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/
417             data> 23ja\P\D
418             Partial match: 23ja
419             data> n05\R\D
420              0: n05
421    
422           For  further  information  about  partial matching, see the pcrepartial
423           documentation.
424    
425    
426    CALLOUTS
427    
428           If the pattern contains any callout requests, pcretest's callout  func-
429           tion  is  called  during  matching. This works with both matching func-
430           tions. By default, the called function displays the callout number, the
431           start  and  current  positions in the text at the callout time, and the
432           next pattern item to be tested. For example, the output
433    
434             --->pqrabcdef
435               0    ^  ^     \d
436    
437           indicates that callout number 0 occurred for a match  attempt  starting
438           at  the fourth character of the subject string, when the pointer was at
439           the seventh character of the data, and when the next pattern  item  was
440           \d.  Just  one  circumflex is output if the start and current positions
441           are the same.
442    
443           Callouts numbered 255 are assumed to be automatic callouts, inserted as
444           a  result  of the /C pattern modifier. In this case, instead of showing
445           the callout number, the offset in the pattern, preceded by a  plus,  is
446           output. For example:
447    
448               re> /\d?[A-E]\*/C
449             data> E*
450             --->E*
451              +0 ^      \d?
452              +3 ^      [A-E]
453              +8 ^^     \*
454             +10 ^ ^
455              0: E*
456    
457           The  callout  function  in pcretest returns zero (carry on matching) by
458           default, but you can use a \C item in a data line (as described  above)
459           to change this.
460    
461           Inserting  callouts can be helpful when using pcretest to check compli-
462           cated regular expressions. For further information about callouts,  see
463           the pcrecallout documentation.
464    
465    
466    SAVING AND RELOADING COMPILED PATTERNS
467    
468           The  facilities  described  in  this section are not available when the
469           POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
470           ifier is specified.
471    
472           When the POSIX interface is not in use, you can cause pcretest to write
473           a compiled pattern to a file, by following the modifiers with >  and  a
474           file name.  For example:
475    
476             /pattern/im >/some/file
477    
478           See  the pcreprecompile documentation for a discussion about saving and
479           re-using compiled patterns.
480    
481           The data that is written is binary.  The  first  eight  bytes  are  the
482           length  of  the  compiled  pattern  data  followed by the length of the
483           optional study data, each written as four  bytes  in  big-endian  order
484           (most  significant  byte  first). If there is no study data (either the
485           pattern was not studied, or studying did not return any data), the sec-
486           ond  length  is  zero. The lengths are followed by an exact copy of the
487           compiled pattern. If there is additional study data, this follows imme-
488           diately  after  the  compiled pattern. After writing the file, pcretest
489           expects to read a new pattern.
490    
491           A saved pattern can be reloaded into pcretest by specifing < and a file
492           name  instead  of  a pattern. The name of the file must not contain a <
493           character, as otherwise pcretest will interpret the line as  a  pattern
494           delimited by < characters.  For example:
495    
496              re> </some/file
497             Compiled regex loaded from /some/file
498             No study data
499    
500           When  the pattern has been loaded, pcretest proceeds to read data lines
501           in the usual way.
502    
503           You can copy a file written by pcretest to a different host and  reload
504           it  there,  even  if the new host has opposite endianness to the one on
505           which the pattern was compiled. For example, you can compile on an  i86
506           machine and run on a SPARC machine.
507    
508           File  names  for  saving and reloading can be absolute or relative, but
509           note that the shell facility of expanding a file name that starts  with
510           a tilde (~) is not available.
511    
512           The  ability to save and reload files in pcretest is intended for test-
513           ing and experimentation. It is not intended for production use  because
514           only  a  single pattern can be written to a file. Furthermore, there is
515           no facility for supplying  custom  character  tables  for  use  with  a
516           reloaded  pattern.  If  the  original  pattern was compiled with custom
517           tables, an attempt to match a subject string using a  reloaded  pattern
518           is  likely to cause pcretest to crash.  Finally, if you attempt to load
519           a file that is not in the correct format, the result is undefined.
520    
521    
522  AUTHOR  AUTHOR
523    
524         Philip Hazel <ph10@cam.ac.uk>         Philip Hazel
525         University Computing Service,         University Computing Service,
526         Cambridge CB2 3QG, England.         Cambridge CB2 3QG, England.
527    
528  Last updated: 09 December 2003  Last updated: 28 February 2005
529  Copyright (c) 1997-2003 University of Cambridge.  Copyright (c) 1997-2005 University of Cambridge.
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