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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    
4  If it is given two filename arguments, it reads from the first and writes to  NAME
5  the second. If it is given only one filename argument, it reads from that file         pcretest - a program for testing Perl-compatible regular expressions.
 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  
6    
7  Philip Hazel <ph10@cam.ac.uk>  
8  January 2000  SYNOPSIS
9    
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
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 has  the  /D  (debug)  modifier;  the
28                     internal form is output after compilation.
29    
30           -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.
37    
38           -m        Output  the  size  of each compiled pattern after it has been
39                     compiled. This is equivalent to adding  /M  to  each  regular
40                     expression.   For  compatibility  with  earlier  versions  of
41                     pcretest, -s is a synonym for -m.
42    
43           -o osize  Set the number of elements in the output vector that is  used
44                     when  calling  pcre_exec()  to be osize. The default value is
45                     45, which is enough for 14 capturing subexpressions. The vec-
46                     tor  size  can  be  changed  for individual matching calls by
47                     including \O in the data line (see below).
48    
49           -p        Behave as if each regex has the /P modifier; the POSIX  wrap-
50                     per  API  is used to call PCRE. None of the other options has
51                     any effect when -p is set.
52    
53           -q        Do not output the version number of pcretest at the start  of
54                     execution.
55    
56           -t        Run  each  compile, study, and match many times with a timer,
57                     and output resulting time per compile or match (in  millisec-
58                     onds).  Do  not set -m with -t, because you will then get the
59                     size output a zillion times, and  the  timing  will  be  dis-
60                     torted.
61    
62    
63    DESCRIPTION
64    
65           If  pcretest  is  given two filename arguments, it reads from the first
66           and writes to the second. If it is given only one filename argument, it
67           reads  from  that  file  and writes to stdout. Otherwise, it reads from
68           stdin and writes to stdout, and prompts for each line of  input,  using
69           "re>" to prompt for regular expressions, and "data>" to prompt for data
70           lines.
71    
72           The program handles any number of sets of input on a single input file.
73           Each  set starts with a regular expression, and continues with any num-
74           ber of data lines to be matched against the pattern.
75    
76           Each data line is matched separately and independently. If you want  to
77           do  multiple-line  matches, you have to use the \n escape sequence in a
78           single line of input to encode  the  newline  characters.  The  maximum
79           length of data line is 30,000 characters.
80    
81           An  empty  line signals the end of the data lines, at which point a new
82           regular expression is read. The regular expressions are given  enclosed
83           in any non-alphanumeric delimiters other than backslash, for example
84    
85             /(a|bc)x+yz/
86    
87           White  space before the initial delimiter is ignored. A regular expres-
88           sion may be continued over several input lines, in which case the  new-
89           line  characters  are included within it. It is possible to include the
90           delimiter within the pattern by escaping it, for example
91    
92             /abc\/def/
93    
94           If you do so, the escape and the delimiter form part  of  the  pattern,
95           but  since delimiters are always non-alphanumeric, this does not affect
96           its interpretation.  If the terminating delimiter is  immediately  fol-
97           lowed by a backslash, for example,
98    
99             /abc/\
100    
101           then  a  backslash  is added to the end of the pattern. This is done to
102           provide a way of testing the error condition that arises if  a  pattern
103           finishes with a backslash, because
104    
105             /abc\/
106    
107           is  interpreted as the first line of a pattern that starts with "abc/",
108           causing pcretest to read the next line as a continuation of the regular
109           expression.
110    
111    
112    PATTERN MODIFIERS
113    
114           A  pattern may be followed by any number of modifiers, which are mostly
115           single characters. Following Perl usage, these are  referred  to  below
116           as,  for  example,  "the /i modifier", even though the delimiter of the
117           pattern need not always be a slash, and no slash is used  when  writing
118           modifiers.  Whitespace  may  appear between the final pattern delimiter
119           and the first modifier, and between the modifiers themselves.
120    
121           The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
122           PCRE_DOTALL,  or  PCRE_EXTENDED  options,  respectively, when pcre_com-
123           pile() is called. These four modifier letters have the same  effect  as
124           they do in Perl. For example:
125    
126             /caseless/i
127    
128           The following table shows additional modifiers for setting PCRE options
129           that do not correspond to anything in Perl:
130    
131             /A    PCRE_ANCHORED
132             /C    PCRE_AUTO_CALLOUT
133             /E    PCRE_DOLLAR_ENDONLY
134             /f    PCRE_FIRSTLINE
135             /N    PCRE_NO_AUTO_CAPTURE
136             /U    PCRE_UNGREEDY
137             /X    PCRE_EXTRA
138    
139           Searching for all possible matches within each subject  string  can  be
140           requested  by  the  /g  or  /G modifier. After finding a match, PCRE is
141           called again to search the remainder of the subject string. The differ-
142           ence between /g and /G is that the former uses the startoffset argument
143           to pcre_exec() to start searching at a  new  point  within  the  entire
144           string  (which  is in effect what Perl does), whereas the latter passes
145           over a shortened substring. This makes a  difference  to  the  matching
146           process if the pattern begins with a lookbehind assertion (including \b
147           or \B).
148    
149           If any call to pcre_exec() in a /g or  /G  sequence  matches  an  empty
150           string,  the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
151           flags set in order to search for another, non-empty, match at the  same
152           point.   If  this  second  match fails, the start offset is advanced by
153           one, and the normal match is retried. This imitates the way  Perl  han-
154           dles such cases when using the /g modifier or the split() function.
155    
156           There are yet more modifiers for controlling the way pcretest operates.
157    
158           The /+ modifier requests that as well as outputting the substring  that
159           matched  the  entire  pattern,  pcretest  should in addition output the
160           remainder of the subject string. This is useful  for  tests  where  the
161           subject contains multiple copies of the same substring.
162    
163           The  /L modifier must be followed directly by the name of a locale, for
164           example,
165    
166             /pattern/Lfr_FR
167    
168           For this reason, it must be the last modifier. The given locale is set,
169           pcre_maketables()  is called to build a set of character tables for the
170           locale, and this is then passed to pcre_compile()  when  compiling  the
171           regular  expression.  Without  an  /L  modifier,  NULL is passed as the
172           tables pointer; that is, /L applies only to the expression on which  it
173           appears.
174    
175           The  /I  modifier  requests  that pcretest output information about the
176           compiled pattern (whether it is anchored, has a fixed first  character,
177           and  so  on). It does this by calling pcre_fullinfo() after compiling a
178           pattern. If the pattern is studied, the results of that are  also  out-
179           put.
180    
181           The /D modifier is a PCRE debugging feature, which also assumes /I.  It
182           causes the internal form of compiled regular expressions to  be  output
183           after compilation. If the pattern was studied, the information returned
184           is also output.
185    
186           The /F modifier causes pcretest to flip the byte order of the fields in
187           the  compiled  pattern  that  contain  2-byte  and 4-byte numbers. This
188           facility is for testing the feature in PCRE that allows it  to  execute
189           patterns that were compiled on a host with a different endianness. This
190           feature is not available when the POSIX  interface  to  PCRE  is  being
191           used,  that is, when the /P pattern modifier is specified. See also the
192           section about saving and reloading compiled patterns below.
193    
194           The /S modifier causes pcre_study() to be called after  the  expression
195           has been compiled, and the results used when the expression is matched.
196    
197           The /M modifier causes the size of memory block used to hold  the  com-
198           piled pattern to be output.
199    
200           The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
201           rather than its native API. When this  is  done,  all  other  modifiers
202           except  /i,  /m, and /+ are ignored. REG_ICASE is set if /i is present,
203           and REG_NEWLINE is set if /m is present. The  wrapper  functions  force
204           PCRE_DOLLAR_ENDONLY  always, and PCRE_DOTALL unless REG_NEWLINE is set.
205    
206           The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8  option
207           set.  This  turns on support for UTF-8 character handling in PCRE, pro-
208           vided that it was compiled with this  support  enabled.  This  modifier
209           also causes any non-printing characters in output strings to be printed
210           using the \x{hh...} notation if they are valid UTF-8 sequences.
211    
212           If the /? modifier  is  used  with  /8,  it  causes  pcretest  to  call
213           pcre_compile()  with  the  PCRE_NO_UTF8_CHECK  option,  to suppress the
214           checking of the string for UTF-8 validity.
215    
216    
217    DATA LINES
218    
219           Before each data line is passed to pcre_exec(),  leading  and  trailing
220           whitespace  is  removed,  and it is then scanned for \ escapes. Some of
221           these are pretty esoteric features, intended for checking out  some  of
222           the  more  complicated features of PCRE. If you are just testing "ordi-
223           nary" regular expressions, you probably don't need any  of  these.  The
224           following escapes are recognized:
225    
226             \a         alarm (= BEL)
227             \b         backspace
228             \e         escape
229             \f         formfeed
230             \n         newline
231             \r         carriage return
232             \t         tab
233             \v         vertical tab
234             \nnn       octal character (up to 3 octal digits)
235             \xhh       hexadecimal character (up to 2 hex digits)
236             \x{hh...}  hexadecimal character, any number of digits
237                          in UTF-8 mode
238             \A         pass the PCRE_ANCHORED option to pcre_exec()
239             \B         pass the PCRE_NOTBOL option to pcre_exec()
240             \Cdd       call pcre_copy_substring() for substring dd
241                          after a successful match (number less than 32)
242             \Cname     call pcre_copy_named_substring() for substring
243                          "name" after a successful match (name termin-
244                          ated by next non alphanumeric character)
245             \C+        show the current captured substrings at callout
246                          time
247             \C-        do not supply a callout function
248             \C!n       return 1 instead of 0 when callout number n is
249                          reached
250             \C!n!m     return 1 instead of 0 when callout number n is
251                          reached for the nth time
252             \C*n       pass the number n (may be negative) as callout
253                          data; this is used as the callout return value
254             \D         use the pcre_dfa_exec() match function
255             \F         only shortest match for pcre_dfa_exec()
256             \Gdd       call pcre_get_substring() for substring dd
257                          after a successful match (number less than 32)
258             \Gname     call pcre_get_named_substring() for substring
259                          "name" after a successful match (name termin-
260                          ated by next non-alphanumeric character)
261             \L         call pcre_get_substringlist() after a
262                          successful match
263             \M         discover the minimum MATCH_LIMIT and
264                          MATCH_LIMIT_RECURSION settings
265             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
266             \Odd       set the size of the output vector passed to
267                          pcre_exec() to dd (any number of digits)
268             \P         pass the PCRE_PARTIAL option to pcre_exec()
269                          or pcre_dfa_exec()
270             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
271             \S         output details of memory get/free calls during matching
272             \Z         pass the PCRE_NOTEOL option to pcre_exec()
273             \?         pass the PCRE_NO_UTF8_CHECK option to
274                          pcre_exec()
275             \>dd       start the match at offset dd (any number of digits);
276                          this sets the startoffset argument for pcre_exec()
277    
278           A  backslash  followed by anything else just escapes the anything else.
279           If the very last character is a backslash, it is ignored. This gives  a
280           way  of  passing  an empty line as data, since a real empty line termi-
281           nates the data input.
282    
283           If \M is present, pcretest calls pcre_exec() several times,  with  dif-
284           ferent  values  in  the match_limit and match_limit_recursion fields of
285           the pcre_extra data structure, until it finds the minimum  numbers  for
286           each parameter that allow pcre_exec() to complete. The match_limit num-
287           ber is a measure of the amount of backtracking that  takes  place,  and
288           checking it out can be instructive. For most simple matches, the number
289           is quite small, but for patterns with very large  numbers  of  matching
290           possibilities,  it can become large very quickly with increasing length
291           of subject string. The match_limit_recursion number is a measure of how
292           much  stack  (or,  if  PCRE is compiled with NO_RECURSE, how much heap)
293           memory is needed to complete the match attempt.
294    
295           When \O is used, the value specified may be higher or  lower  than  the
296           size set by the -O command line option (or defaulted to 45); \O applies
297           only to the call of pcre_exec() for the line in which it appears.
298    
299           If the /P modifier was present on the pattern, causing the POSIX  wrap-
300           per  API  to  be  used, the only option-setting sequences that have any
301           effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL,  respectively,
302           to be passed to regexec().
303    
304           The  use of \x{hh...} to represent UTF-8 characters is not dependent on
305           the use of the /8 modifier on the pattern.  It  is  recognized  always.
306           There  may  be  any number of hexadecimal digits inside the braces. The
307           result is from one to six bytes, encoded according to the UTF-8  rules.
308    
309    
310    THE ALTERNATIVE MATCHING FUNCTION
311    
312           By   default,  pcretest  uses  the  standard  PCRE  matching  function,
313           pcre_exec() to match each data line. From release 6.0, PCRE supports an
314           alternative  matching  function,  pcre_dfa_test(),  which operates in a
315           different way, and has some restrictions. The differences  between  the
316           two functions are described in the pcrematching documentation.
317    
318           If  a data line contains the \D escape sequence, or if the command line
319           contains the -dfa option, the alternative matching function is  called.
320           This function finds all possible matches at a given point. If, however,
321           the \F escape sequence is present in the data line, it stops after  the
322           first match is found. This is always the shortest possible match.
323    
324    
325    DEFAULT OUTPUT FROM PCRETEST
326    
327           This  section  describes  the output when the normal matching function,
328           pcre_exec(), is being used.
329    
330           When a match succeeds, pcretest outputs the list of captured substrings
331           that  pcre_exec()  returns,  starting with number 0 for the string that
332           matched the whole pattern. Otherwise, it outputs "No match" or "Partial
333           match"  when  pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
334           TIAL, respectively, and otherwise the PCRE negative error number.  Here
335           is an example of an interactive pcretest run.
336    
337             $ pcretest
338             PCRE version 5.00 07-Sep-2004
339    
340               re> /^abc(\d+)/
341             data> abc123
342              0: abc123
343              1: 123
344             data> xyz
345             No match
346    
347           If  the strings contain any non-printing characters, they are output as
348           \0x escapes, or as \x{...} escapes if the /8 modifier  was  present  on
349           the  pattern.  If  the pattern has the /+ modifier, the output for sub-
350           string 0 is followed by the the rest of the subject string,  identified
351           by "0+" like this:
352    
353               re> /cat/+
354             data> cataract
355              0: cat
356              0+ aract
357    
358           If  the  pattern  has  the /g or /G modifier, the results of successive
359           matching attempts are output in sequence, like this:
360    
361               re> /\Bi(\w\w)/g
362             data> Mississippi
363              0: iss
364              1: ss
365              0: iss
366              1: ss
367              0: ipp
368              1: pp
369    
370           "No match" is output only if the first match attempt fails.
371    
372           If any of the sequences \C, \G, or \L are present in a data  line  that
373           is  successfully  matched,  the substrings extracted by the convenience
374           functions are output with C, G, or L after the string number instead of
375           a colon. This is in addition to the normal full list. The string length
376           (that is, the return from the extraction function) is given  in  paren-
377           theses after each string for \C and \G.
378    
379           Note  that  while patterns can be continued over several lines (a plain
380           ">" prompt is used for continuations), data lines may not. However new-
381           lines can be included in data by means of the \n escape.
382    
383    
384    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
385    
386           When  the  alternative  matching function, pcre_dfa_exec(), is used (by
387           means of the \D escape sequence or the -dfa command line  option),  the
388           output  consists  of  a list of all the matches that start at the first
389           point in the subject where there is at least one match. For example:
390    
391               re> /(tang|tangerine|tan)/
392             data> yellow tangerine\D
393              0: tangerine
394              1: tang
395              2: tan
396    
397           (Using the normal matching function on this data  finds  only  "tang".)
398           The  longest matching string is always given first (and numbered zero).
399    
400           If /gP is present on  the  pattern,  the  search  for  further  matches
401           resumes at the end of the longest match. For example:
402    
403               re> /(tang|tangerine|tan)/g
404             data> yellow tangerine and tangy sultana\D
405              0: tangerine
406              1: tang
407              2: tan
408              0: tang
409              1: tan
410              0: tan
411    
412           Since  the  matching  function  does not support substring capture, the
413           escape sequences that are concerned with captured  substrings  are  not
414           relevant.
415    
416    
417    RESTARTING AFTER A PARTIAL MATCH
418    
419           When the alternative matching function has given the PCRE_ERROR_PARTIAL
420           return, indicating that the subject partially matched the pattern,  you
421           can  restart  the match with additional subject data by means of the \R
422           escape sequence. For example:
423    
424               re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/
425             data> 23ja\P\D
426             Partial match: 23ja
427             data> n05\R\D
428              0: n05
429    
430           For further information about partial  matching,  see  the  pcrepartial
431           documentation.
432    
433    
434    CALLOUTS
435    
436           If  the pattern contains any callout requests, pcretest's callout func-
437           tion is called during matching. This works  with  both  matching  func-
438           tions. By default, the called function displays the callout number, the
439           start and current positions in the text at the callout  time,  and  the
440           next pattern item to be tested. For example, the output
441    
442             --->pqrabcdef
443               0    ^  ^     \d
444    
445           indicates  that  callout number 0 occurred for a match attempt starting
446           at the fourth character of the subject string, when the pointer was  at
447           the  seventh  character of the data, and when the next pattern item was
448           \d. Just one circumflex is output if the start  and  current  positions
449           are the same.
450    
451           Callouts numbered 255 are assumed to be automatic callouts, inserted as
452           a result of the /C pattern modifier. In this case, instead  of  showing
453           the  callout  number, the offset in the pattern, preceded by a plus, is
454           output. For example:
455    
456               re> /\d?[A-E]\*/C
457             data> E*
458             --->E*
459              +0 ^      \d?
460              +3 ^      [A-E]
461              +8 ^^     \*
462             +10 ^ ^
463              0: E*
464    
465           The callout function in pcretest returns zero (carry  on  matching)  by
466           default,  but you can use a \C item in a data line (as described above)
467           to change this.
468    
469           Inserting callouts can be helpful when using pcretest to check  compli-
470           cated  regular expressions. For further information about callouts, see
471           the pcrecallout documentation.
472    
473    
474    SAVING AND RELOADING COMPILED PATTERNS
475    
476           The facilities described in this section are  not  available  when  the
477           POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
478           ifier is specified.
479    
480           When the POSIX interface is not in use, you can cause pcretest to write
481           a  compiled  pattern to a file, by following the modifiers with > and a
482           file name.  For example:
483    
484             /pattern/im >/some/file
485    
486           See the pcreprecompile documentation for a discussion about saving  and
487           re-using compiled patterns.
488    
489           The  data  that  is  written  is  binary. The first eight bytes are the
490           length of the compiled pattern data  followed  by  the  length  of  the
491           optional  study  data,  each  written as four bytes in big-endian order
492           (most significant byte first). If there is no study  data  (either  the
493           pattern was not studied, or studying did not return any data), the sec-
494           ond length is zero. The lengths are followed by an exact  copy  of  the
495           compiled pattern. If there is additional study data, this follows imme-
496           diately after the compiled pattern. After writing  the  file,  pcretest
497           expects to read a new pattern.
498    
499           A saved pattern can be reloaded into pcretest by specifing < and a file
500           name instead of a pattern. The name of the file must not  contain  a  <
501           character,  as  otherwise pcretest will interpret the line as a pattern
502           delimited by < characters.  For example:
503    
504              re> </some/file
505             Compiled regex loaded from /some/file
506             No study data
507    
508           When the pattern has been loaded, pcretest proceeds to read data  lines
509           in the usual way.
510    
511           You  can copy a file written by pcretest to a different host and reload
512           it there, even if the new host has opposite endianness to  the  one  on
513           which  the pattern was compiled. For example, you can compile on an i86
514           machine and run on a SPARC machine.
515    
516           File names for saving and reloading can be absolute  or  relative,  but
517           note  that the shell facility of expanding a file name that starts with
518           a tilde (~) is not available.
519    
520           The ability to save and reload files in pcretest is intended for  test-
521           ing  and experimentation. It is not intended for production use because
522           only a single pattern can be written to a file. Furthermore,  there  is
523           no  facility  for  supplying  custom  character  tables  for use with a
524           reloaded pattern. If the original  pattern  was  compiled  with  custom
525           tables,  an  attempt to match a subject string using a reloaded pattern
526           is likely to cause pcretest to crash.  Finally, if you attempt to  load
527           a file that is not in the correct format, the result is undefined.
528    
529    
530    AUTHOR
531    
532           Philip Hazel
533           University Computing Service,
534           Cambridge CB2 3QG, England.
535    
536    Last updated: 18 January 2006
537    Copyright (c) 1997-2006 University of Cambridge.

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