/[pcre]/code/trunk/doc/pcretest.txt
ViewVC logotype

Diff of /code/trunk/doc/pcretest.txt

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

revision 47 by nigel, Sat Feb 24 21:39:29 2007 UTC revision 75 by nigel, Sat Feb 24 21:40:37 2007 UTC
# Line 1  Line 1 
1  The pcretest program  PCRETEST(1)                                                        PCRETEST(1)
 --------------------  
2    
 This program is intended for testing PCRE, but it can also be used for  
 experimenting with regular expressions.  
3    
 If it is given two filename arguments, it reads from the first and writes to  
 the second. If it is given only one filename argument, it reads from that file  
 and writes to stdout. Otherwise, it reads from stdin and writes to stdout, and  
 prompts for each line of input, using "re>" to prompt for regular expressions,  
 and "data>" to prompt for data lines.  
   
 The program handles any number of sets of input on a single input file. Each  
 set starts with a regular expression, and continues with any number of data  
 lines to be matched against the pattern. An empty line signals the end of the  
 data lines, at which point a new regular expression is read. The regular  
 expressions are given enclosed in any non-alphameric delimiters other than  
 backslash, for example  
   
   /(a|bc)x+yz/  
   
 White space before the initial delimiter is ignored. A regular expression may  
 be continued over several input lines, in which case the newline characters are  
 included within it. See the test input files in the testdata directory for many  
 examples. It is possible to include the delimiter within the pattern by  
 escaping it, for example  
   
   /abc\/def/  
   
 If you do so, the escape and the delimiter form part of the pattern, but since  
 delimiters are always non-alphameric, this does not affect its interpretation.  
 If the terminating delimiter is immediately followed by a backslash, for  
 example,  
   
   /abc/\  
   
 then a backslash is added to the end of the pattern. This is done to provide a  
 way of testing the error condition that arises if a pattern finishes with a  
 backslash, because  
   
   /abc\/  
   
 is interpreted as the first line of a pattern that starts with "abc/", causing  
 pcretest to read the next line as a continuation of the regular expression.  
   
 The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,  
 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For  
 example:  
   
   /caseless/i  
   
 These modifier letters have the same effect as they do in Perl. There are  
 others which set PCRE options that do not correspond to anything in Perl: /A,  
 /E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.  
   
 Searching for all possible matches within each subject string can be requested  
 by the /g or /G modifier. After finding a match, PCRE is called again to search  
 the remainder of the subject string. The difference between /g and /G is that  
 the former uses the startoffset argument to pcre_exec() to start searching at  
 a new point within the entire string (which is in effect what Perl does),  
 whereas the latter passes over a shortened substring. This makes a difference  
 to the matching process if the pattern begins with a lookbehind assertion  
 (including \b or \B).  
   
 If any call to pcre_exec() in a /g or /G sequence matches an empty string, the  
 next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED flags set in order  
 to search for another, non-empty, match at the same point. If this second match  
 fails, the start offset is advanced by one, and the normal match is retried.  
 This imitates the way Perl handles such cases when using the /g modifier or the  
 split() function.  
   
 There are a number of other modifiers for controlling the way pcretest  
 operates.  
   
 The /+ modifier requests that as well as outputting the substring that matched  
 the entire pattern, pcretest should in addition output the remainder of the  
 subject string. This is useful for tests where the subject contains multiple  
 copies of the same substring.  
   
 The /L modifier must be followed directly by the name of a locale, for example,  
   
   /pattern/Lfr  
   
 For this reason, it must be the last modifier letter. The given locale is set,  
 pcre_maketables() is called to build a set of character tables for the locale,  
 and this is then passed to pcre_compile() when compiling the regular  
 expression. Without an /L modifier, NULL is passed as the tables pointer; that  
 is, /L applies only to the expression on which it appears.  
   
 The /I modifier requests that pcretest output information about the compiled  
 expression (whether it is anchored, has a fixed first character, and so on). It  
 does this by calling pcre_fullinfo() after compiling an expression, and  
 outputting the information it gets back. If the pattern is studied, the results  
 of that are also output.  
   
 The /D modifier is a PCRE debugging feature, which also assumes /I. It causes  
 the internal form of compiled regular expressions to be output after  
 compilation.  
   
 The /S modifier causes pcre_study() to be called after the expression has been  
 compiled, and the results used when the expression is matched.  
   
 The /M modifier causes the size of memory block used to hold the compiled  
 pattern to be output.  
   
 Finally, the /P modifier causes pcretest to call PCRE via the POSIX wrapper API  
 rather than its native API. When this is done, all other modifiers except /i,  
 /m, and /+ are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is  
 set if /m is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always,  
 and PCRE_DOTALL unless REG_NEWLINE is set.  
   
 Before each data line is passed to pcre_exec(), leading and trailing whitespace  
 is removed, and it is then scanned for \ escapes. The following are recognized:  
   
   \a     alarm (= BEL)  
   \b     backspace  
   \e     escape  
   \f     formfeed  
   \n     newline  
   \r     carriage return  
   \t     tab  
   \v     vertical tab  
   \nnn   octal character (up to 3 octal digits)  
   \xhh   hexadecimal character (up to 2 hex digits)  
   
   \A     pass the PCRE_ANCHORED option to pcre_exec()  
   \B     pass the PCRE_NOTBOL option to pcre_exec()  
   \Cdd   call pcre_copy_substring() for substring dd after a successful match  
            (any decimal number less than 32)  
   \Gdd   call pcre_get_substring() for substring dd after a successful match  
            (any decimal number less than 32)  
   \L     call pcre_get_substringlist() after a successful match  
   \N     pass the PCRE_NOTEMPTY option to pcre_exec()  
   \Odd   set the size of the output vector passed to pcre_exec() to dd  
            (any number of decimal digits)  
   \Z     pass the PCRE_NOTEOL option to pcre_exec()  
   
 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 terminates the data input.  
   
 If /P was present on the regex, causing the POSIX wrapper API to be used, only  
 \B, and \Z have any effect, causing REG_NOTBOL and REG_NOTEOL to be passed to  
 regexec() respectively.  
   
 When a match succeeds, pcretest outputs the list of captured substrings that  
 pcre_exec() returns, starting with number 0 for the string that matched the  
 whole pattern. Here is an example of an interactive pcretest run.  
   
   $ pcretest  
   PCRE version 2.06 08-Jun-1999  
   
     re> /^abc(\d+)/  
   data> abc123  
    0: abc123  
    1: 123  
   data> xyz  
   No match  
   
 If the strings contain any non-printing characters, they are output as \0x  
 escapes. If the pattern has the /+ modifier, then the output for substring 0 is  
 followed by the the rest of the subject string, identified by "0+" like this:  
   
     re> /cat/+  
   data> cataract  
    0: cat  
    0+ aract  
   
 If the pattern has the /g or /G modifier, the results of successive matching  
 attempts are output in sequence, like this:  
   
     re> /\Bi(\w\w)/g  
   data> Mississippi  
    0: iss  
    1: ss  
    0: iss  
    1: ss  
    0: ipp  
    1: pp  
   
 "No match" is output only if the first match attempt fails.  
   
 If any of \C, \G, or \L are present in a data line that is successfully  
 matched, the substrings extracted by the convenience functions are output with  
 C, G, or L after the string number instead of a colon. This is in addition to  
 the normal full list. The string length (that is, the return from the  
 extraction function) is given in parentheses after each string for \C and \G.  
   
 Note that while patterns can be continued over several lines (a plain ">"  
 prompt is used for continuations), data lines may not. However newlines can be  
 included in data by means of the \n escape.  
   
 If the -p option is given to pcretest, it is equivalent to adding /P to each  
 regular expression: the POSIX wrapper API is used to call PCRE. None of the  
 following flags has any effect in this case.  
   
 If the option -d is given to pcretest, it is equivalent to adding /D to each  
 regular expression: the internal form is output after compilation.  
   
 If the option -i is given to pcretest, it is equivalent to adding /I to each  
 regular expression: information about the compiled pattern is given after  
 compilation.  
   
 If the option -m is given to pcretest, it outputs the size of each compiled  
 pattern after it has been compiled. It is equivalent to adding /M to each  
 regular expression. For compatibility with earlier versions of pcretest, -s is  
 a synonym for -m.  
   
 If the -t option is given, each compile, study, and match is run 20000 times  
 while being timed, and the resulting time per compile or match is output in  
 milliseconds. Do not set -t with -s, because you will then get the size output  
 20000 times and the timing will be distorted. If you want to change the number  
 of repetitions used for timing, edit the definition of LOOPREPEAT at the top of  
 pcretest.c  
4    
5  Philip Hazel <ph10@cam.ac.uk>  NAME
6  January 2000         pcretest - a program for testing Perl-compatible regular expressions.
7    
8    SYNOPSIS
9    
10           pcretest [-C] [-d] [-i] [-m] [-o osize] [-p] [-t] [source]
11                [destination]
12    
13           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
15           expressions.  This document describes the features of the test program;
16           for details of the regular expressions themselves, see the  pcrepattern
17           documentation. For details of the PCRE library function calls and their
18           options, see the pcreapi documentation.
19    
20    
21    OPTIONS
22    
23           -C        Output the version number of the PCRE library, and all avail-
24                     able   information  about  the  optional  features  that  are
25                     included, and then exit.
26    
27           -d        Behave as if each regex had  the  /D  (debug)  modifier;  the
28                     internal form is output after compilation.
29    
30           -i        Behave  as  if  each  regex  had the /I modifier; information
31                     about the compiled pattern is given after compilation.
32    
33           -m        Output the size of each compiled pattern after  it  has  been
34                     compiled.  This  is  equivalent  to adding /M to each regular
35                     expression.  For  compatibility  with  earlier  versions   of
36                     pcretest, -s is a synonym for -m.
37    
38           -o osize  Set  the number of elements in the output vector that is used
39                     when calling pcre_exec() to be osize. The  default  value  is
40                     45, which is enough for 14 capturing subexpressions. The vec-
41                     tor size can be changed  for  individual  matching  calls  by
42                     including \O in the data line (see below).
43    
44           -p        Behave  as  if  each regex has /P modifier; the POSIX wrapper
45                     API is used to call PCRE. None of the other options  has  any
46                     effect when -p is set.
47    
48           -t        Run  each  compile, study, and match many times with a timer,
49                     and output resulting time per compile or match (in  millisec-
50                     onds).  Do  not set -m with -t, because you will then get the
51                     size output a zillion times, and  the  timing  will  be  dis-
52                     torted.
53    
54    
55    DESCRIPTION
56    
57           If  pcretest  is  given two filename arguments, it reads from the first
58           and writes to the second. If it is given only one filename argument, it
59           reads  from  that  file  and writes to stdout. Otherwise, it reads from
60           stdin and writes to stdout, and prompts for each line of  input,  using
61           "re>" to prompt for regular expressions, and "data>" to prompt for data
62           lines.
63    
64           The program handles any number of sets of input on a single input file.
65           Each  set starts with a regular expression, and continues with any num-
66           ber of data lines to be matched against the pattern.
67    
68           Each data line is matched separately and independently. If you want  to
69           do  multiple-line  matches, you have to use the \n escape sequence in a
70           single line of input to encode  the  newline  characters.  The  maximum
71           length of data line is 30,000 characters.
72    
73           An  empty  line signals the end of the data lines, at which point a new
74           regular expression is read. The regular expressions are given  enclosed
75           in any non-alphanumeric delimiters other than backslash, for example
76    
77             /(a|bc)x+yz/
78    
79           White  space before the initial delimiter is ignored. A regular expres-
80           sion may be continued over several input lines, in which case the  new-
81           line  characters  are included within it. It is possible to include the
82           delimiter within the pattern by escaping it, for example
83    
84             /abc\/def/
85    
86           If you do so, the escape and the delimiter form part  of  the  pattern,
87           but  since delimiters are always non-alphanumeric, this does not affect
88           its interpretation.  If the terminating delimiter is  immediately  fol-
89           lowed by a backslash, for example,
90    
91             /abc/\
92    
93           then  a  backslash  is added to the end of the pattern. This is done to
94           provide a way of testing the error condition that arises if  a  pattern
95           finishes with a backslash, because
96    
97             /abc\/
98    
99           is  interpreted as the first line of a pattern that starts with "abc/",
100           causing pcretest to read the next line as a continuation of the regular
101           expression.
102    
103    
104    PATTERN MODIFIERS
105    
106           A  pattern may be followed by any number of modifiers, which are mostly
107           single characters. Following Perl usage, these are  referred  to  below
108           as,  for  example,  "the /i modifier", even though the delimiter of the
109           pattern need not always be a slash, and no slash is used  when  writing
110           modifiers.  Whitespace  may  appear between the final pattern delimiter
111           and the first modifier, and between the modifiers themselves.
112    
113           The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
114           PCRE_DOTALL,  or  PCRE_EXTENDED  options,  respectively, when pcre_com-
115           pile() is called. These four modifier letters have the same  effect  as
116           they do in Perl. For example:
117    
118             /caseless/i
119    
120           The following table shows additional modifiers for setting PCRE options
121           that do not correspond to anything in Perl:
122    
123             /A    PCRE_ANCHORED
124             /C    PCRE_AUTO_CALLOUT
125             /E    PCRE_DOLLAR_ENDONLY
126             /N    PCRE_NO_AUTO_CAPTURE
127             /U    PCRE_UNGREEDY
128             /X    PCRE_EXTRA
129    
130           Searching for all possible matches within each subject  string  can  be
131           requested  by  the  /g  or  /G modifier. After finding a match, PCRE is
132           called again to search the remainder of the subject string. The differ-
133           ence between /g and /G is that the former uses the startoffset argument
134           to pcre_exec() to start searching at a  new  point  within  the  entire
135           string  (which  is in effect what Perl does), whereas the latter passes
136           over a shortened substring. This makes a  difference  to  the  matching
137           process if the pattern begins with a lookbehind assertion (including \b
138           or \B).
139    
140           If any call to pcre_exec() in a /g or  /G  sequence  matches  an  empty
141           string,  the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
142           flags set in order to search for another, non-empty, match at the  same
143           point.   If  this  second  match fails, the start offset is advanced by
144           one, and the normal match is retried. This imitates the way  Perl  han-
145           dles such cases when using the /g modifier or the split() function.
146    
147           There are yet more modifiers for controlling the way pcretest operates.
148    
149           The /+ modifier requests that as well as outputting the substring  that
150           matched  the  entire  pattern,  pcretest  should in addition output the
151           remainder of the subject string. This is useful  for  tests  where  the
152           subject contains multiple copies of the same substring.
153    
154           The  /L modifier must be followed directly by the name of a locale, for
155           example,
156    
157             /pattern/Lfr_FR
158    
159           For this reason, it must be the last modifier. The given locale is set,
160           pcre_maketables()  is called to build a set of character tables for the
161           locale, and this is then passed to pcre_compile()  when  compiling  the
162           regular  expression.  Without  an  /L  modifier,  NULL is passed as the
163           tables pointer; that is, /L applies only to the expression on which  it
164           appears.
165    
166           The  /I  modifier  requests  that pcretest output information about the
167           compiled pattern (whether it is anchored, has a fixed first  character,
168           and  so  on). It does this by calling pcre_fullinfo() after compiling a
169           pattern. If the pattern is studied, the results of that are  also  out-
170           put.
171    
172           The /D modifier is a PCRE debugging feature, which also assumes /I.  It
173           causes the internal form of compiled regular expressions to  be  output
174           after compilation. If the pattern was studied, the information returned
175           is also output.
176    
177           The /F modifier causes pcretest to flip the byte order of the fields in
178           the  compiled  pattern  that  contain  2-byte  and 4-byte numbers. This
179           facility is for testing the feature in PCRE that allows it  to  execute
180           patterns that were compiled on a host with a different endianness. This
181           feature is not available when the POSIX  interface  to  PCRE  is  being
182           used,  that is, when the /P pattern modifier is specified. See also the
183           section about saving and reloading compiled patterns below.
184    
185           The /S modifier causes pcre_study() to be called after  the  expression
186           has been compiled, and the results used when the expression is matched.
187    
188           The /M modifier causes the size of memory block used to hold  the  com-
189           piled pattern to be output.
190    
191           The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
192           rather than its native API. When this  is  done,  all  other  modifiers
193           except  /i,  /m, and /+ are ignored. REG_ICASE is set if /i is present,
194           and REG_NEWLINE is set if /m is present. The  wrapper  functions  force
195           PCRE_DOLLAR_ENDONLY  always, and PCRE_DOTALL unless REG_NEWLINE is set.
196    
197           The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8  option
198           set.  This  turns on support for UTF-8 character handling in PCRE, pro-
199           vided that it was compiled with this  support  enabled.  This  modifier
200           also causes any non-printing characters in output strings to be printed
201           using the \x{hh...} notation if they are valid UTF-8 sequences.
202    
203           If the /? modifier  is  used  with  /8,  it  causes  pcretest  to  call
204           pcre_compile()  with  the  PCRE_NO_UTF8_CHECK  option,  to suppress the
205           checking of the string for UTF-8 validity.
206    
207    
208    DATA LINES
209    
210           Before each data line is passed to pcre_exec(),  leading  and  trailing
211           whitespace  is  removed,  and it is then scanned for \ escapes. Some of
212           these are pretty esoteric features, intended for checking out  some  of
213           the  more  complicated features of PCRE. If you are just testing "ordi-
214           nary" regular expressions, you probably don't need any  of  these.  The
215           following escapes are recognized:
216    
217             \a         alarm (= BEL)
218             \b         backspace
219             \e         escape
220             \f         formfeed
221             \n         newline
222             \r         carriage return
223             \t         tab
224             \v         vertical tab
225             \nnn       octal character (up to 3 octal digits)
226             \xhh       hexadecimal character (up to 2 hex digits)
227             \x{hh...}  hexadecimal character, any number of digits
228                          in UTF-8 mode
229             \A         pass the PCRE_ANCHORED option to pcre_exec()
230             \B         pass the PCRE_NOTBOL option to pcre_exec()
231             \Cdd       call pcre_copy_substring() for substring dd
232                          after a successful match (number less than 32)
233             \Cname     call pcre_copy_named_substring() for substring
234                          "name" after a successful match (name termin-
235                          ated by next non alphanumeric character)
236             \C+        show the current captured substrings at callout
237                          time
238             \C-        do not supply a callout function
239             \C!n       return 1 instead of 0 when callout number n is
240                          reached
241             \C!n!m     return 1 instead of 0 when callout number n is
242                          reached for the nth time
243             \C*n       pass the number n (may be negative) as callout
244                          data; this is used as the callout return value
245             \Gdd       call pcre_get_substring() for substring dd
246                          after a successful match (number less than 32)
247             \Gname     call pcre_get_named_substring() for substring
248                          "name" after a successful match (name termin-
249                          ated by next non-alphanumeric character)
250             \L         call pcre_get_substringlist() after a
251                          successful match
252             \M         discover the minimum MATCH_LIMIT setting
253             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
254             \Odd       set the size of the output vector passed to
255                          pcre_exec() to dd (any number of digits)
256             \P         pass the PCRE_PARTIAL option to pcre_exec()
257             \S         output details of memory get/free calls during matching
258             \Z         pass the PCRE_NOTEOL option to pcre_exec()
259             \?         pass the PCRE_NO_UTF8_CHECK option to
260                          pcre_exec()
261             \>dd       start the match at offset dd (any number of digits);
262                          this sets the startoffset argument for pcre_exec()
263    
264           A  backslash  followed by anything else just escapes the anything else.
265           If the very last character is a backslash, it is ignored. This gives  a
266           way  of  passing  an empty line as data, since a real empty line termi-
267           nates the data input.
268    
269           If \M is present, pcretest calls pcre_exec() several times,  with  dif-
270           ferent  values  in  the match_limit field of the pcre_extra data struc-
271           ture, until it finds the minimum number that is needed for  pcre_exec()
272           to  complete.  This  number is a measure of the amount of recursion and
273           backtracking that takes place, and checking it out can be  instructive.
274           For  most  simple  matches, the number is quite small, but for patterns
275           with very large numbers of matching possibilities, it can become  large
276           very quickly with increasing length of subject string.
277    
278           When  \O  is  used, the value specified may be higher or lower than the
279           size set by the -O command line option (or defaulted to 45); \O applies
280           only to the call of pcre_exec() for the line in which it appears.
281    
282           If  the /P modifier was present on the pattern, causing the POSIX wrap-
283           per API to be used, only \B and \Z have any effect, causing  REG_NOTBOL
284           and REG_NOTEOL to be passed to regexec() respectively.
285    
286           The  use of \x{hh...} to represent UTF-8 characters is not dependent on
287           the use of the /8 modifier on the pattern.  It  is  recognized  always.
288           There  may  be  any number of hexadecimal digits inside the braces. The
289           result is from one to six bytes, encoded according to the UTF-8  rules.
290    
291    
292    OUTPUT FROM PCRETEST
293    
294           When a match succeeds, pcretest outputs the list of captured substrings
295           that pcre_exec() returns, starting with number 0 for  the  string  that
296           matched the whole pattern. Otherwise, it outputs "No match" or "Partial
297           match" when pcre_exec() returns PCRE_ERROR_NOMATCH  or  PCRE_ERROR_PAR-
298           TIAL,  respectively, and otherwise the PCRE negative error number. Here
299           is an example of an interactive pcretest run.
300    
301             $ pcretest
302             PCRE version 5.00 07-Sep-2004
303    
304               re> /^abc(\d+)/
305             data> abc123
306              0: abc123
307              1: 123
308             data> xyz
309             No match
310    
311           If the strings contain any non-printing characters, they are output  as
312           \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
313           the pattern. If the pattern has the /+ modifier, the  output  for  sub-
314           string  0 is followed by the the rest of the subject string, identified
315           by "0+" like this:
316    
317               re> /cat/+
318             data> cataract
319              0: cat
320              0+ aract
321    
322           If the pattern has the /g or /G modifier,  the  results  of  successive
323           matching attempts are output in sequence, like this:
324    
325               re> /\Bi(\w\w)/g
326             data> Mississippi
327              0: iss
328              1: ss
329              0: iss
330              1: ss
331              0: ipp
332              1: pp
333    
334           "No match" is output only if the first match attempt fails.
335    
336           If  any  of the sequences \C, \G, or \L are present in a data line that
337           is successfully matched, the substrings extracted  by  the  convenience
338           functions are output with C, G, or L after the string number instead of
339           a colon. This is in addition to the normal full list. The string length
340           (that  is,  the return from the extraction function) is given in paren-
341           theses after each string for \C and \G.
342    
343           Note that while patterns can be continued over several lines  (a  plain
344           ">" prompt is used for continuations), data lines may not. However new-
345           lines can be included in data by means of the \n escape.
346    
347    
348    CALLOUTS
349    
350           If the pattern contains any callout requests, pcretest's callout  func-
351           tion  is  called  during  matching. By default, it displays the callout
352           number, the start and current positions in  the  text  at  the  callout
353           time, and the next pattern item to be tested. For example, the output
354    
355             --->pqrabcdef
356               0    ^  ^     \d
357    
358           indicates  that  callout number 0 occurred for a match attempt starting
359           at the fourth character of the subject string, when the pointer was  at
360           the  seventh  character of the data, and when the next pattern item was
361           \d. Just one circumflex is output if the start  and  current  positions
362           are the same.
363    
364           Callouts numbered 255 are assumed to be automatic callouts, inserted as
365           a result of the /C pattern modifier. In this case, instead  of  showing
366           the  callout  number, the offset in the pattern, preceded by a plus, is
367           output. For example:
368    
369               re> /\d?[A-E]\*/C
370             data> E*
371             --->E*
372              +0 ^      \d?
373              +3 ^      [A-E]
374              +8 ^^     \*
375             +10 ^ ^
376              0: E*
377    
378           The callout function in pcretest returns zero (carry  on  matching)  by
379           default, but you can use an \C item in a data line (as described above)
380           to change this.
381    
382           Inserting callouts can be helpful when using pcretest to check  compli-
383           cated  regular expressions. For further information about callouts, see
384           the pcrecallout documentation.
385    
386    
387    SAVING AND RELOADING COMPILED PATTERNS
388    
389           The facilities described in this section are  not  available  when  the
390           POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
391           ifier is specified.
392    
393           When the POSIX interface is not in use, you can cause pcretest to write
394           a  compiled  pattern to a file, by following the modifiers with > and a
395           file name.  For example:
396    
397             /pattern/im >/some/file
398    
399           See the pcreprecompile documentation for a discussion about saving  and
400           re-using compiled patterns.
401    
402           The  data  that  is  written  is  binary. The first eight bytes are the
403           length of the compiled pattern data  followed  by  the  length  of  the
404           optional  study  data,  each  written as four bytes in big-endian order
405           (most significant byte first). If there is no study  data  (either  the
406           pattern was not studied, or studying did not return any data), the sec-
407           ond length is zero. The lengths are followed by an exact  copy  of  the
408           compiled pattern. If there is additional study data, this follows imme-
409           diately after the compiled pattern. After writing  the  file,  pcretest
410           expects to read a new pattern.
411    
412           A saved pattern can be reloaded into pcretest by specifing < and a file
413           name instead of a pattern. The name of the file must not  contain  a  <
414           character,  as  otherwise pcretest will interpret the line as a pattern
415           delimited by < characters.  For example:
416    
417              re> </some/file
418             Compiled regex loaded from /some/file
419             No study data
420    
421           When the pattern has been loaded, pcretest proceeds to read data  lines
422           in the usual way.
423    
424           You  can copy a file written by pcretest to a different host and reload
425           it there, even if the new host has opposite endianness to  the  one  on
426           which  the pattern was compiled. For example, you can compile on an i86
427           machine and run on a SPARC machine.
428    
429           File names for saving and reloading can be absolute  or  relative,  but
430           note  that the shell facility of expanding a file name that starts with
431           a tilde (~) is not available.
432    
433           The ability to save and reload files in pcretest is intended for  test-
434           ing  and experimentation. It is not intended for production use because
435           only a single pattern can be written to a file. Furthermore,  there  is
436           no  facility  for  supplying  custom  character  tables  for use with a
437           reloaded pattern. If the original  pattern  was  compiled  with  custom
438           tables,  an  attempt to match a subject string using a reloaded pattern
439           is likely to cause pcretest to crash.  Finally, if you attempt to  load
440           a file that is not in the correct format, the result is undefined.
441    
442    
443    AUTHOR
444    
445           Philip Hazel <ph10@cam.ac.uk>
446           University Computing Service,
447           Cambridge CB2 3QG, England.
448    
449    Last updated: 10 September 2004
450    Copyright (c) 1997-2004 University of Cambridge.

Legend:
Removed from v.47  
changed lines
  Added in v.75

  ViewVC Help
Powered by ViewVC 1.1.5