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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 [options] [source] [destination]
11    
12           pcretest  was written as a test program for the PCRE regular expression
13           library itself, but it can also be used for experimenting with  regular
14           expressions.  This document describes the features of the test program;
15           for details of the regular expressions themselves, see the  pcrepattern
16           documentation. For details of the PCRE library function calls and their
17           options, see the pcreapi documentation.
18    
19    
20    OPTIONS
21    
22           -C        Output the version number of the PCRE library, and all avail-
23                     able   information  about  the  optional  features  that  are
24                     included, and then exit.
25    
26           -d        Behave as if each regex has  the  /D  (debug)  modifier;  the
27                     internal form is output after compilation.
28    
29           -dfa      Behave  as if each data line contains the \D escape sequence;
30                     this    causes    the    alternative    matching    function,
31                     pcre_dfa_exec(),   to   be   used  instead  of  the  standard
32                     pcre_exec() function (more detail is given below).
33    
34           -i        Behave as if each regex  has  the  /I  modifier;  information
35                     about the compiled pattern is given after compilation.
36    
37           -m        Output  the  size  of each compiled pattern after it has been
38                     compiled. This is equivalent to adding  /M  to  each  regular
39                     expression.   For  compatibility  with  earlier  versions  of
40                     pcretest, -s is a synonym for -m.
41    
42           -o osize  Set the number of elements in the output vector that is  used
43                     when  calling  pcre_exec()  to be osize. The default value is
44                     45, which is enough for 14 capturing subexpressions. The vec-
45                     tor  size  can  be  changed  for individual matching calls by
46                     including \O in the data line (see below).
47    
48           -p        Behave as if each regex has the /P modifier; the POSIX  wrap-
49                     per  API  is used to call PCRE. None of the other options has
50                     any effect when -p is set.
51    
52           -q        Do not output the version number of pcretest at the start  of
53                     execution.
54    
55           -S size   On  Unix-like  systems,  set the size of the runtime stack to
56                     size megabytes.
57    
58           -t        Run each compile, study, and match many times with  a  timer,
59                     and  output resulting time per compile or match (in millisec-
60                     onds). Do not set -m with -t, because you will then  get  the
61                     size  output  a  zillion  times,  and the timing will be dis-
62                     torted.
63    
64    
65    DESCRIPTION
66    
67           If pcretest is given two filename arguments, it reads  from  the  first
68           and writes to the second. If it is given only one filename argument, it
69           reads from that file and writes to stdout.  Otherwise,  it  reads  from
70           stdin  and  writes to stdout, and prompts for each line of input, using
71           "re>" to prompt for regular expressions, and "data>" to prompt for data
72           lines.
73    
74           The program handles any number of sets of input on a single input file.
75           Each set starts with a regular expression, and continues with any  num-
76           ber of data lines to be matched against the pattern.
77    
78           Each  data line is matched separately and independently. If you want to
79           do multi-line matches, you have to use the \n escape sequence (or \r or
80           \r\n,  depending  on  the newline setting) in a single line of input to
81           encode the newline characters. There is no limit on the length of  data
82           lines; the input buffer is automatically extended if it is too small.
83    
84           An  empty  line signals the end of the data lines, at which point a new
85           regular expression is read. The regular expressions are given  enclosed
86           in any non-alphanumeric delimiters other than backslash, for example:
87    
88             /(a|bc)x+yz/
89    
90           White  space before the initial delimiter is ignored. A regular expres-
91           sion may be continued over several input lines, in which case the  new-
92           line  characters  are included within it. It is possible to include the
93           delimiter within the pattern by escaping it, for example
94    
95             /abc\/def/
96    
97           If you do so, the escape and the delimiter form part  of  the  pattern,
98           but  since delimiters are always non-alphanumeric, this does not affect
99           its interpretation.  If the terminating delimiter is  immediately  fol-
100           lowed by a backslash, for example,
101    
102             /abc/\
103    
104           then  a  backslash  is added to the end of the pattern. This is done to
105           provide a way of testing the error condition that arises if  a  pattern
106           finishes with a backslash, because
107    
108             /abc\/
109    
110           is  interpreted as the first line of a pattern that starts with "abc/",
111           causing pcretest to read the next line as a continuation of the regular
112           expression.
113    
114    
115    PATTERN MODIFIERS
116    
117           A  pattern may be followed by any number of modifiers, which are mostly
118           single characters. Following Perl usage, these are  referred  to  below
119           as,  for  example,  "the /i modifier", even though the delimiter of the
120           pattern need not always be a slash, and no slash is used  when  writing
121           modifiers.  Whitespace  may  appear between the final pattern delimiter
122           and the first modifier, and between the modifiers themselves.
123    
124           The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
125           PCRE_DOTALL,  or  PCRE_EXTENDED  options,  respectively, when pcre_com-
126           pile() is called. These four modifier letters have the same  effect  as
127           they do in Perl. For example:
128    
129             /caseless/i
130    
131           The following table shows additional modifiers for setting PCRE options
132           that do not correspond to anything in Perl:
133    
134             /A       PCRE_ANCHORED
135             /C       PCRE_AUTO_CALLOUT
136             /E       PCRE_DOLLAR_ENDONLY
137             /f       PCRE_FIRSTLINE
138             /J       PCRE_DUPNAMES
139             /N       PCRE_NO_AUTO_CAPTURE
140             /U       PCRE_UNGREEDY
141             /X       PCRE_EXTRA
142             /<cr>    PCRE_NEWLINE_CR
143             /<lf>    PCRE_NEWLINE_LF
144             /<crlf>  PCRE_NEWLINE_CRLF
145    
146           Those specifying line endings are literal strings as shown. Details  of
147           the  meanings of these PCRE options are given in the pcreapi documenta-
148           tion.
149    
150       Finding all matches in a string
151    
152           Searching for all possible matches within each subject  string  can  be
153           requested  by  the  /g  or  /G modifier. After finding a match, PCRE is
154           called again to search the remainder of the subject string. The differ-
155           ence between /g and /G is that the former uses the startoffset argument
156           to pcre_exec() to start searching at a  new  point  within  the  entire
157           string  (which  is in effect what Perl does), whereas the latter passes
158           over a shortened substring. This makes a  difference  to  the  matching
159           process if the pattern begins with a lookbehind assertion (including \b
160           or \B).
161    
162           If any call to pcre_exec() in a /g or  /G  sequence  matches  an  empty
163           string,  the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
164           flags set in order to search for another, non-empty, match at the  same
165           point.   If  this  second  match fails, the start offset is advanced by
166           one, and the normal match is retried. This imitates the way  Perl  han-
167           dles such cases when using the /g modifier or the split() function.
168    
169       Other modifiers
170    
171           There are yet more modifiers for controlling the way pcretest operates.
172    
173           The /+ modifier requests that as well as outputting the substring  that
174           matched  the  entire  pattern,  pcretest  should in addition output the
175           remainder of the subject string. This is useful  for  tests  where  the
176           subject contains multiple copies of the same substring.
177    
178           The  /L modifier must be followed directly by the name of a locale, for
179           example,
180    
181             /pattern/Lfr_FR
182    
183           For this reason, it must be the last modifier. The given locale is set,
184           pcre_maketables()  is called to build a set of character tables for the
185           locale, and this is then passed to pcre_compile()  when  compiling  the
186           regular  expression.  Without  an  /L  modifier,  NULL is passed as the
187           tables pointer; that is, /L applies only to the expression on which  it
188           appears.
189    
190           The  /I  modifier  requests  that pcretest output information about the
191           compiled pattern (whether it is anchored, has a fixed first  character,
192           and  so  on). It does this by calling pcre_fullinfo() after compiling a
193           pattern. If the pattern is studied, the results of that are  also  out-
194           put.
195    
196           The /D modifier is a PCRE debugging feature, which also assumes /I.  It
197           causes the internal form of compiled regular expressions to  be  output
198           after compilation. If the pattern was studied, the information returned
199           is also output.
200    
201           The /F modifier causes pcretest to flip the byte order of the fields in
202           the  compiled  pattern  that  contain  2-byte  and 4-byte numbers. This
203           facility is for testing the feature in PCRE that allows it  to  execute
204           patterns that were compiled on a host with a different endianness. This
205           feature is not available when the POSIX  interface  to  PCRE  is  being
206           used,  that is, when the /P pattern modifier is specified. See also the
207           section about saving and reloading compiled patterns below.
208    
209           The /S modifier causes pcre_study() to be called after  the  expression
210           has been compiled, and the results used when the expression is matched.
211    
212           The /M modifier causes the size of memory block used to hold  the  com-
213           piled pattern to be output.
214    
215           The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
216           rather than its native API. When this  is  done,  all  other  modifiers
217           except  /i,  /m, and /+ are ignored. REG_ICASE is set if /i is present,
218           and REG_NEWLINE is set if /m is present. The  wrapper  functions  force
219           PCRE_DOLLAR_ENDONLY  always, and PCRE_DOTALL unless REG_NEWLINE is set.
220    
221           The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8  option
222           set.  This  turns on support for UTF-8 character handling in PCRE, pro-
223           vided that it was compiled with this  support  enabled.  This  modifier
224           also causes any non-printing characters in output strings to be printed
225           using the \x{hh...} notation if they are valid UTF-8 sequences.
226    
227           If the /? modifier  is  used  with  /8,  it  causes  pcretest  to  call
228           pcre_compile()  with  the  PCRE_NO_UTF8_CHECK  option,  to suppress the
229           checking of the string for UTF-8 validity.
230    
231    
232    DATA LINES
233    
234           Before each data line is passed to pcre_exec(),  leading  and  trailing
235           whitespace  is  removed,  and it is then scanned for \ escapes. Some of
236           these are pretty esoteric features, intended for checking out  some  of
237           the  more  complicated features of PCRE. If you are just testing "ordi-
238           nary" regular expressions, you probably don't need any  of  these.  The
239           following escapes are recognized:
240    
241             \a         alarm (= BEL)
242             \b         backspace
243             \e         escape
244             \f         formfeed
245             \n         newline
246             \qdd       set the PCRE_MATCH_LIMIT limit to dd
247                          (any number of digits)
248             \r         carriage return
249             \t         tab
250             \v         vertical tab
251             \nnn       octal character (up to 3 octal digits)
252             \xhh       hexadecimal character (up to 2 hex digits)
253             \x{hh...}  hexadecimal character, any number of digits
254                          in UTF-8 mode
255             \A         pass the PCRE_ANCHORED option to pcre_exec()
256                          or pcre_dfa_exec()
257             \B         pass the PCRE_NOTBOL option to pcre_exec()
258                          or pcre_dfa_exec()
259             \Cdd       call pcre_copy_substring() for substring dd
260                          after a successful match (number less than 32)
261             \Cname     call pcre_copy_named_substring() for substring
262                          "name" after a successful match (name termin-
263                          ated by next non alphanumeric character)
264             \C+        show the current captured substrings at callout
265                          time
266             \C-        do not supply a callout function
267             \C!n       return 1 instead of 0 when callout number n is
268                          reached
269             \C!n!m     return 1 instead of 0 when callout number n is
270                          reached for the nth time
271             \C*n       pass the number n (may be negative) as callout
272                          data; this is used as the callout return value
273             \D         use the pcre_dfa_exec() match function
274             \F         only shortest match for pcre_dfa_exec()
275             \Gdd       call pcre_get_substring() for substring dd
276                          after a successful match (number less than 32)
277             \Gname     call pcre_get_named_substring() for substring
278                          "name" after a successful match (name termin-
279                          ated by next non-alphanumeric character)
280             \L         call pcre_get_substringlist() after a
281                          successful match
282             \M         discover the minimum MATCH_LIMIT and
283                          MATCH_LIMIT_RECURSION settings
284             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
285                          or pcre_dfa_exec()
286             \Odd       set the size of the output vector passed to
287                          pcre_exec() to dd (any number of digits)
288             \P         pass the PCRE_PARTIAL option to pcre_exec()
289                          or pcre_dfa_exec()
290             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
291                          (any number of digits)
292             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
293             \S         output details of memory get/free calls during matching
294             \Z         pass the PCRE_NOTEOL option to pcre_exec()
295                          or pcre_dfa_exec()
296             \?         pass the PCRE_NO_UTF8_CHECK option to
297                          pcre_exec() or pcre_dfa_exec()
298             \>dd       start the match at offset dd (any number of digits);
299                          this sets the startoffset argument for pcre_exec()
300                          or pcre_dfa_exec()
301             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
302                          or pcre_dfa_exec()
303             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
304                          or pcre_dfa_exec()
305             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
306                          or pcre_dfa_exec()
307    
308           The  escapes  that specify line endings are literal strings, exactly as
309           shown.  A backslash followed by anything else just escapes the anything
310           else.  If  the  very last character is a backslash, it is ignored. This
311           gives a way of passing an empty line as data, since a real  empty  line
312           terminates the data input.
313    
314           If  \M  is present, pcretest calls pcre_exec() several times, with dif-
315           ferent values in the match_limit and  match_limit_recursion  fields  of
316           the  pcre_extra  data structure, until it finds the minimum numbers for
317           each parameter that allow pcre_exec() to complete. The match_limit num-
318           ber  is  a  measure of the amount of backtracking that takes place, and
319           checking it out can be instructive. For most simple matches, the number
320           is  quite  small,  but for patterns with very large numbers of matching
321           possibilities, it can become large very quickly with increasing  length
322           of subject string. The match_limit_recursion number is a measure of how
323           much stack (or, if PCRE is compiled with  NO_RECURSE,  how  much  heap)
324           memory is needed to complete the match attempt.
325    
326           When  \O  is  used, the value specified may be higher or lower than the
327           size set by the -O command line option (or defaulted to 45); \O applies
328           only to the call of pcre_exec() for the line in which it appears.
329    
330           If  the /P modifier was present on the pattern, causing the POSIX wrap-
331           per API to be used, the only option-setting  sequences  that  have  any
332           effect  are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
333           to be passed to regexec().
334    
335           The use of \x{hh...} to represent UTF-8 characters is not dependent  on
336           the  use  of  the  /8 modifier on the pattern. It is recognized always.
337           There may be any number of hexadecimal digits inside  the  braces.  The
338           result  is from one to six bytes, encoded according to the UTF-8 rules.
339    
340    
341    THE ALTERNATIVE MATCHING FUNCTION
342    
343           By  default,  pcretest  uses  the  standard  PCRE  matching   function,
344           pcre_exec() to match each data line. From release 6.0, PCRE supports an
345           alternative matching function, pcre_dfa_test(),  which  operates  in  a
346           different  way,  and has some restrictions. The differences between the
347           two functions are described in the pcrematching documentation.
348    
349           If a data line contains the \D escape sequence, or if the command  line
350           contains  the -dfa option, the alternative matching function is called.
351           This function finds all possible matches at a given point. If, however,
352           the  \F escape sequence is present in the data line, it stops after the
353           first match is found. This is always the shortest possible match.
354    
355    
356    DEFAULT OUTPUT FROM PCRETEST
357    
358           This section describes the output when the  normal  matching  function,
359           pcre_exec(), is being used.
360    
361           When a match succeeds, pcretest outputs the list of captured substrings
362           that pcre_exec() returns, starting with number 0 for  the  string  that
363           matched the whole pattern. Otherwise, it outputs "No match" or "Partial
364           match" when pcre_exec() returns PCRE_ERROR_NOMATCH  or  PCRE_ERROR_PAR-
365           TIAL,  respectively, and otherwise the PCRE negative error number. Here
366           is an example of an interactive pcretest run.
367    
368             $ pcretest
369             PCRE version 5.00 07-Sep-2004
370    
371               re> /^abc(\d+)/
372             data> abc123
373              0: abc123
374              1: 123
375             data> xyz
376             No match
377    
378           If the strings contain any non-printing characters, they are output  as
379           \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
380           the pattern. If the pattern has the /+ modifier, the  output  for  sub-
381           string  0 is followed by the the rest of the subject string, identified
382           by "0+" like this:
383    
384               re> /cat/+
385             data> cataract
386              0: cat
387              0+ aract
388    
389           If the pattern has the /g or /G modifier,  the  results  of  successive
390           matching attempts are output in sequence, like this:
391    
392               re> /\Bi(\w\w)/g
393             data> Mississippi
394              0: iss
395              1: ss
396              0: iss
397              1: ss
398              0: ipp
399              1: pp
400    
401           "No match" is output only if the first match attempt fails.
402    
403           If  any  of the sequences \C, \G, or \L are present in a data line that
404           is successfully matched, the substrings extracted  by  the  convenience
405           functions are output with C, G, or L after the string number instead of
406           a colon. This is in addition to the normal full list. The string length
407           (that  is,  the return from the extraction function) is given in paren-
408           theses after each string for \C and \G.
409    
410           Note that while patterns can be continued over several lines  (a  plain
411           ">" prompt is used for continuations), data lines may not. However new-
412           lines can be included in data by means of the \n escape (or \r or  \r\n
413           for those newline settings).
414    
415    
416    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
417    
418           When  the  alternative  matching function, pcre_dfa_exec(), is used (by
419           means of the \D escape sequence or the -dfa command line  option),  the
420           output  consists  of  a list of all the matches that start at the first
421           point in the subject where there is at least one match. For example:
422    
423               re> /(tang|tangerine|tan)/
424             data> yellow tangerine\D
425              0: tangerine
426              1: tang
427              2: tan
428    
429           (Using the normal matching function on this data  finds  only  "tang".)
430           The  longest matching string is always given first (and numbered zero).
431    
432           If /gP is present on  the  pattern,  the  search  for  further  matches
433           resumes at the end of the longest match. For example:
434    
435               re> /(tang|tangerine|tan)/g
436             data> yellow tangerine and tangy sultana\D
437              0: tangerine
438              1: tang
439              2: tan
440              0: tang
441              1: tan
442              0: tan
443    
444           Since  the  matching  function  does not support substring capture, the
445           escape sequences that are concerned with captured  substrings  are  not
446           relevant.
447    
448    
449    RESTARTING AFTER A PARTIAL MATCH
450    
451           When the alternative matching function has given the PCRE_ERROR_PARTIAL
452           return, indicating that the subject partially matched the pattern,  you
453           can  restart  the match with additional subject data by means of the \R
454           escape sequence. For example:
455    
456               re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/
457             data> 23ja\P\D
458             Partial match: 23ja
459             data> n05\R\D
460              0: n05
461    
462           For further information about partial  matching,  see  the  pcrepartial
463           documentation.
464    
465    
466    CALLOUTS
467    
468           If  the pattern contains any callout requests, pcretest's callout func-
469           tion is called during matching. This works  with  both  matching  func-
470           tions. By default, the called function displays the callout number, the
471           start and current positions in the text at the callout  time,  and  the
472           next pattern item to be tested. For example, the output
473    
474             --->pqrabcdef
475               0    ^  ^     \d
476    
477           indicates  that  callout number 0 occurred for a match attempt starting
478           at the fourth character of the subject string, when the pointer was  at
479           the  seventh  character of the data, and when the next pattern item was
480           \d. Just one circumflex is output if the start  and  current  positions
481           are the same.
482    
483           Callouts numbered 255 are assumed to be automatic callouts, inserted as
484           a result of the /C pattern modifier. In this case, instead  of  showing
485           the  callout  number, the offset in the pattern, preceded by a plus, is
486           output. For example:
487    
488               re> /\d?[A-E]\*/C
489             data> E*
490             --->E*
491              +0 ^      \d?
492              +3 ^      [A-E]
493              +8 ^^     \*
494             +10 ^ ^
495              0: E*
496    
497           The callout function in pcretest returns zero (carry  on  matching)  by
498           default,  but you can use a \C item in a data line (as described above)
499           to change this.
500    
501           Inserting callouts can be helpful when using pcretest to check  compli-
502           cated  regular expressions. For further information about callouts, see
503           the pcrecallout documentation.
504    
505    
506    SAVING AND RELOADING COMPILED PATTERNS
507    
508           The facilities described in this section are  not  available  when  the
509           POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
510           ifier is specified.
511    
512           When the POSIX interface is not in use, you can cause pcretest to write
513           a  compiled  pattern to a file, by following the modifiers with > and a
514           file name.  For example:
515    
516             /pattern/im >/some/file
517    
518           See the pcreprecompile documentation for a discussion about saving  and
519           re-using compiled patterns.
520    
521           The  data  that  is  written  is  binary. The first eight bytes are the
522           length of the compiled pattern data  followed  by  the  length  of  the
523           optional  study  data,  each  written as four bytes in big-endian order
524           (most significant byte first). If there is no study  data  (either  the
525           pattern was not studied, or studying did not return any data), the sec-
526           ond length is zero. The lengths are followed by an exact  copy  of  the
527           compiled pattern. If there is additional study data, this follows imme-
528           diately after the compiled pattern. After writing  the  file,  pcretest
529           expects to read a new pattern.
530    
531           A saved pattern can be reloaded into pcretest by specifing < and a file
532           name instead of a pattern. The name of the file must not  contain  a  <
533           character,  as  otherwise pcretest will interpret the line as a pattern
534           delimited by < characters.  For example:
535    
536              re> </some/file
537             Compiled regex loaded from /some/file
538             No study data
539    
540           When the pattern has been loaded, pcretest proceeds to read data  lines
541           in the usual way.
542    
543           You  can copy a file written by pcretest to a different host and reload
544           it there, even if the new host has opposite endianness to  the  one  on
545           which  the pattern was compiled. For example, you can compile on an i86
546           machine and run on a SPARC machine.
547    
548           File names for saving and reloading can be absolute  or  relative,  but
549           note  that the shell facility of expanding a file name that starts with
550           a tilde (~) is not available.
551    
552           The ability to save and reload files in pcretest is intended for  test-
553           ing  and experimentation. It is not intended for production use because
554           only a single pattern can be written to a file. Furthermore,  there  is
555           no  facility  for  supplying  custom  character  tables  for use with a
556           reloaded pattern. If the original  pattern  was  compiled  with  custom
557           tables,  an  attempt to match a subject string using a reloaded pattern
558           is likely to cause pcretest to crash.  Finally, if you attempt to  load
559           a file that is not in the correct format, the result is undefined.
560    
561    
562    AUTHOR
563    
564           Philip Hazel
565           University Computing Service,
566           Cambridge CB2 3QG, England.
567    
568    Last updated: 29 June 2006
569    Copyright (c) 1997-2006 University of Cambridge.

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