/[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 512 by ph10, Tue Mar 30 11:11:52 2010 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    
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           -b        Behave as if each regex has the /B (show bytecode)  modifier;
23                     the internal form is output after compilation.
24    
25           -C        Output the version number of the PCRE library, and all avail-
26                     able  information  about  the  optional  features  that   are
27                     included, and then exit.
28    
29           -d        Behave  as  if  each  regex  has the /D (debug) modifier; the
30                     internal form and information about the compiled  pattern  is
31                     output after compilation; -d is equivalent to -b -i.
32    
33           -dfa      Behave  as if each data line contains the \D escape sequence;
34                     this    causes    the    alternative    matching    function,
35                     pcre_dfa_exec(),   to   be   used  instead  of  the  standard
36                     pcre_exec() function (more detail is given below).
37    
38           -help     Output a brief summary these options and then exit.
39    
40           -i        Behave as if each regex  has  the  /I  modifier;  information
41                     about the compiled pattern is given after compilation.
42    
43           -M        Behave  as if each data line contains the \M escape sequence;
44                     this causes PCRE to  discover  the  minimum  MATCH_LIMIT  and
45                     MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
46                     edly with different limits.
47    
48           -m        Output the size of each compiled pattern after  it  has  been
49                     compiled.  This  is  equivalent  to adding /M to each regular
50                     expression.  For  compatibility  with  earlier  versions   of
51                     pcretest, -s is a synonym for -m.
52    
53           -o osize  Set  the number of elements in the output vector that is used
54                     when calling pcre_exec() or pcre_dfa_exec() to be osize.  The
55                     default  value is 45, which is enough for 14 capturing subex-
56                     pressions  for  pcre_exec()  or  22  different  matches   for
57                     pcre_dfa_exec().  The vector size can be changed for individ-
58                     ual matching calls by including \O  in  the  data  line  (see
59                     below).
60    
61           -p        Behave  as if each regex has the /P modifier; the POSIX wrap-
62                     per API is used to call PCRE. None of the other  options  has
63                     any effect when -p is set.
64    
65           -q        Do  not output the version number of pcretest at the start of
66                     execution.
67    
68           -S size   On Unix-like systems, set the size of the  runtime  stack  to
69                     size megabytes.
70    
71           -t        Run  each  compile, study, and match many times with a timer,
72                     and output resulting time per compile or match (in  millisec-
73                     onds).  Do  not set -m with -t, because you will then get the
74                     size output a zillion times, and  the  timing  will  be  dis-
75                     torted.  You  can  control  the number of iterations that are
76                     used for timing by following -t with a number (as a  separate
77                     item on the command line). For example, "-t 1000" would iter-
78                     ate 1000 times. The default is to iterate 500000 times.
79    
80           -tm       This is like -t except that it times only the matching phase,
81                     not the compile or study phases.
82    
83    
84    DESCRIPTION
85    
86           If  pcretest  is  given two filename arguments, it reads from the first
87           and writes to the second. If it is given only one filename argument, it
88           reads  from  that  file  and writes to stdout. Otherwise, it reads from
89           stdin and writes to stdout, and prompts for each line of  input,  using
90           "re>" to prompt for regular expressions, and "data>" to prompt for data
91           lines.
92    
93           When pcretest is built, a configuration  option  can  specify  that  it
94           should  be  linked  with the libreadline library. When this is done, if
95           the input is from a terminal, it is read using the readline() function.
96           This  provides line-editing and history facilities. The output from the
97           -help option states whether or not readline() will be used.
98    
99           The program handles any number of sets of input on a single input file.
100           Each  set starts with a regular expression, and continues with any num-
101           ber of data lines to be matched against the pattern.
102    
103           Each data line is matched separately and independently. If you want  to
104           do multi-line matches, you have to use the \n escape sequence (or \r or
105           \r\n, etc., depending on the newline setting) in a single line of input
106           to  encode  the  newline  sequences. There is no limit on the length of
107           data lines; the input buffer is automatically extended  if  it  is  too
108           small.
109    
110           An  empty  line signals the end of the data lines, at which point a new
111           regular expression is read. The regular expressions are given  enclosed
112           in any non-alphanumeric delimiters other than backslash, for example:
113    
114             /(a|bc)x+yz/
115    
116           White  space before the initial delimiter is ignored. A regular expres-
117           sion may be continued over several input lines, in which case the  new-
118           line  characters  are included within it. It is possible to include the
119           delimiter within the pattern by escaping it, for example
120    
121             /abc\/def/
122    
123           If you do so, the escape and the delimiter form part  of  the  pattern,
124           but  since delimiters are always non-alphanumeric, this does not affect
125           its interpretation.  If the terminating delimiter is  immediately  fol-
126           lowed by a backslash, for example,
127    
128             /abc/\
129    
130           then  a  backslash  is added to the end of the pattern. This is done to
131           provide a way of testing the error condition that arises if  a  pattern
132           finishes with a backslash, because
133    
134             /abc\/
135    
136           is  interpreted as the first line of a pattern that starts with "abc/",
137           causing pcretest to read the next line as a continuation of the regular
138           expression.
139    
140    
141    PATTERN MODIFIERS
142    
143           A  pattern may be followed by any number of modifiers, which are mostly
144           single characters. Following Perl usage, these are  referred  to  below
145           as,  for  example,  "the /i modifier", even though the delimiter of the
146           pattern need not always be a slash, and no slash is used  when  writing
147           modifiers.  Whitespace  may  appear between the final pattern delimiter
148           and the first modifier, and between the modifiers themselves.
149    
150           The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
151           PCRE_DOTALL,  or  PCRE_EXTENDED  options,  respectively, when pcre_com-
152           pile() is called. These four modifier letters have the same  effect  as
153           they do in Perl. For example:
154    
155             /caseless/i
156    
157           The following table shows additional modifiers for setting PCRE options
158           that do not correspond to anything in Perl:
159    
160             /A              PCRE_ANCHORED
161             /C              PCRE_AUTO_CALLOUT
162             /E              PCRE_DOLLAR_ENDONLY
163             /f              PCRE_FIRSTLINE
164             /J              PCRE_DUPNAMES
165             /N              PCRE_NO_AUTO_CAPTURE
166             /U              PCRE_UNGREEDY
167             /X              PCRE_EXTRA
168             /<JS>           PCRE_JAVASCRIPT_COMPAT
169             /<cr>           PCRE_NEWLINE_CR
170             /<lf>           PCRE_NEWLINE_LF
171             /<crlf>         PCRE_NEWLINE_CRLF
172             /<anycrlf>      PCRE_NEWLINE_ANYCRLF
173             /<any>          PCRE_NEWLINE_ANY
174             /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
175             /<bsr_unicode>  PCRE_BSR_UNICODE
176    
177           Those specifying line ending sequences are literal  strings  as  shown,
178           but  the  letters  can  be  in either case. This example sets multiline
179           matching with CRLF as the line ending sequence:
180    
181             /^abc/m<crlf>
182    
183           Details of the meanings of these PCRE options are given in the  pcreapi
184           documentation.
185    
186       Finding all matches in a string
187    
188           Searching  for  all  possible matches within each subject string can be
189           requested by the /g or /G modifier. After  finding  a  match,  PCRE  is
190           called again to search the remainder of the subject string. The differ-
191           ence between /g and /G is that the former uses the startoffset argument
192           to  pcre_exec()  to  start  searching  at a new point within the entire
193           string (which is in effect what Perl does), whereas the  latter  passes
194           over  a  shortened  substring.  This makes a difference to the matching
195           process if the pattern begins with a lookbehind assertion (including \b
196           or \B).
197    
198           If  any  call  to  pcre_exec()  in a /g or /G sequence matches an empty
199           string, the next  call  is  done  with  the  PCRE_NOTEMPTY_ATSTART  and
200           PCRE_ANCHORED  flags  set  in  order  to search for another, non-empty,
201           match at the same point. If this second match fails, the  start  offset
202           is  advanced  by  one  character, and the normal match is retried. This
203           imitates the way Perl handles such cases when using the /g modifier  or
204           the split() function.
205    
206       Other modifiers
207    
208           There are yet more modifiers for controlling the way pcretest operates.
209    
210           The  /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
211           set. This turns on support for UTF-8 character handling in  PCRE,  pro-
212           vided  that  it  was  compiled with this support enabled. This modifier
213           also causes any non-printing characters in output strings to be printed
214           using the \x{hh...} notation if they are valid UTF-8 sequences.
215    
216           If  the  /?  modifier  is  used  with  /8,  it  causes pcretest to call
217           pcre_compile() with the  PCRE_NO_UTF8_CHECK  option,  to  suppress  the
218           checking of the string for UTF-8 validity.
219    
220           The  /+ modifier requests that as well as outputting the substring that
221           matched the entire pattern, pcretest  should  in  addition  output  the
222           remainder  of  the  subject  string. This is useful for tests where the
223           subject contains multiple copies of the same substring.
224    
225           The /B modifier is a debugging feature. It requests that pcretest  out-
226           put  a representation of the compiled byte code after compilation. Nor-
227           mally this information contains length and offset values;  however,  if
228           /Z  is also present, this data is replaced by spaces. This is a special
229           feature for use in the automatic test scripts; it ensures that the same
230           output is generated for different internal link sizes.
231    
232           The  /D modifier is a PCRE debugging feature, and is equivalent to /BI,
233           that is, both the /B and the /I modifiers.
234    
235           The /F modifier causes pcretest to flip the byte order of the fields in
236           the  compiled  pattern  that  contain  2-byte  and 4-byte numbers. This
237           facility is for testing the feature in PCRE that allows it  to  execute
238           patterns that were compiled on a host with a different endianness. This
239           feature is not available when the POSIX  interface  to  PCRE  is  being
240           used,  that is, when the /P pattern modifier is specified. See also the
241           section about saving and reloading compiled patterns below.
242    
243           The /I modifier requests that pcretest  output  information  about  the
244           compiled  pattern (whether it is anchored, has a fixed first character,
245           and so on). It does this by calling pcre_fullinfo() after  compiling  a
246           pattern.  If  the pattern is studied, the results of that are also out-
247           put.
248    
249           The /K modifier requests pcretest to show names from backtracking  con-
250           trol  verbs  that  are  returned  from  calls to pcre_exec(). It causes
251           pcretest to create a pcre_extra block if one has not already been  cre-
252           ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
253           the mark field within it, every time that pcre_exec() is called. If the
254           variable  that  the  mark field points to is non-NULL for a match, non-
255           match, or partial match, pcretest prints the string to which it points.
256           For a match, this is shown on a line by itself, tagged with "MK:".  For
257           a non-match it is added to the message.
258    
259           The /L modifier must be followed directly by the name of a locale,  for
260           example,
261    
262             /pattern/Lfr_FR
263    
264           For this reason, it must be the last modifier. The given locale is set,
265           pcre_maketables() is called to build a set of character tables for  the
266           locale,  and  this  is then passed to pcre_compile() when compiling the
267           regular expression. Without an /L  modifier,  NULL  is  passed  as  the
268           tables  pointer; that is, /L applies only to the expression on which it
269           appears.
270    
271           The /M modifier causes the size of memory block used to hold  the  com-
272           piled pattern to be output.
273    
274           The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
275           rather than its native API. When this  is  done,  all  other  modifiers
276           except  /i,  /m, and /+ are ignored. REG_ICASE is set if /i is present,
277           and REG_NEWLINE is set if /m is present. The  wrapper  functions  force
278           PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
279    
280           The  /S  modifier causes pcre_study() to be called after the expression
281           has been compiled, and the results used when the expression is matched.
282    
283    
284    DATA LINES
285    
286           Before each data line is passed to pcre_exec(),  leading  and  trailing
287           whitespace  is  removed,  and it is then scanned for \ escapes. Some of
288           these are pretty esoteric features, intended for checking out  some  of
289           the  more  complicated features of PCRE. If you are just testing "ordi-
290           nary" regular expressions, you probably don't need any  of  these.  The
291           following escapes are recognized:
292    
293             \a         alarm (BEL, \x07)
294             \b         backspace (\x08)
295             \e         escape (\x27)
296             \f         formfeed (\x0c)
297             \n         newline (\x0a)
298             \qdd       set the PCRE_MATCH_LIMIT limit to dd
299                          (any number of digits)
300             \r         carriage return (\x0d)
301             \t         tab (\x09)
302             \v         vertical tab (\x0b)
303             \nnn       octal character (up to 3 octal digits)
304             \xhh       hexadecimal character (up to 2 hex digits)
305             \x{hh...}  hexadecimal character, any number of digits
306                          in UTF-8 mode
307             \A         pass the PCRE_ANCHORED option to pcre_exec()
308                          or pcre_dfa_exec()
309             \B         pass the PCRE_NOTBOL option to pcre_exec()
310                          or pcre_dfa_exec()
311             \Cdd       call pcre_copy_substring() for substring dd
312                          after a successful match (number less than 32)
313             \Cname     call pcre_copy_named_substring() for substring
314                          "name" after a successful match (name termin-
315                          ated by next non alphanumeric character)
316             \C+        show the current captured substrings at callout
317                          time
318             \C-        do not supply a callout function
319             \C!n       return 1 instead of 0 when callout number n is
320                          reached
321             \C!n!m     return 1 instead of 0 when callout number n is
322                          reached for the nth time
323             \C*n       pass the number n (may be negative) as callout
324                          data; this is used as the callout return value
325             \D         use the pcre_dfa_exec() match function
326             \F         only shortest match for pcre_dfa_exec()
327             \Gdd       call pcre_get_substring() for substring dd
328                          after a successful match (number less than 32)
329             \Gname     call pcre_get_named_substring() for substring
330                          "name" after a successful match (name termin-
331                          ated by next non-alphanumeric character)
332             \L         call pcre_get_substringlist() after a
333                          successful match
334             \M         discover the minimum MATCH_LIMIT and
335                          MATCH_LIMIT_RECURSION settings
336             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
337                          or pcre_dfa_exec(); if used twice, pass the
338                          PCRE_NOTEMPTY_ATSTART option
339             \Odd       set the size of the output vector passed to
340                          pcre_exec() to dd (any number of digits)
341             \P         pass the PCRE_PARTIAL_SOFT option to pcre_exec()
342                          or pcre_dfa_exec(); if used twice, pass the
343                          PCRE_PARTIAL_HARD option
344             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
345                          (any number of digits)
346             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
347             \S         output details of memory get/free calls during matching
348             \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
349                          or pcre_dfa_exec()
350             \Z         pass the PCRE_NOTEOL option to pcre_exec()
351                          or pcre_dfa_exec()
352             \?         pass the PCRE_NO_UTF8_CHECK option to
353                          pcre_exec() or pcre_dfa_exec()
354             \>dd       start the match at offset dd (any number of digits);
355                          this sets the startoffset argument for pcre_exec()
356                          or pcre_dfa_exec()
357             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
358                          or pcre_dfa_exec()
359             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
360                          or pcre_dfa_exec()
361             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
362                          or pcre_dfa_exec()
363             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
364                          or pcre_dfa_exec()
365             \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()
366                          or pcre_dfa_exec()
367    
368           The  escapes  that  specify  line ending sequences are literal strings,
369           exactly as shown. No more than one newline setting should be present in
370           any data line.
371    
372           A  backslash  followed by anything else just escapes the anything else.
373           If the very last character is a backslash, it is ignored. This gives  a
374           way  of  passing  an empty line as data, since a real empty line termi-
375           nates the data input.
376    
377           If \M is present, pcretest calls pcre_exec() several times,  with  dif-
378           ferent  values  in  the match_limit and match_limit_recursion fields of
379           the pcre_extra data structure, until it finds the minimum  numbers  for
380           each parameter that allow pcre_exec() to complete. The match_limit num-
381           ber is a measure of the amount of backtracking that  takes  place,  and
382           checking it out can be instructive. For most simple matches, the number
383           is quite small, but for patterns with very large  numbers  of  matching
384           possibilities,  it can become large very quickly with increasing length
385           of subject string. The match_limit_recursion number is a measure of how
386           much  stack  (or,  if  PCRE is compiled with NO_RECURSE, how much heap)
387           memory is needed to complete the match attempt.
388    
389           When \O is used, the value specified may be higher or  lower  than  the
390           size set by the -O command line option (or defaulted to 45); \O applies
391           only to the call of pcre_exec() for the line in which it appears.
392    
393           If the /P modifier was present on the pattern, causing the POSIX  wrap-
394           per  API  to  be  used, the only option-setting sequences that have any
395           effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL,  respectively,
396           to be passed to regexec().
397    
398           The  use of \x{hh...} to represent UTF-8 characters is not dependent on
399           the use of the /8 modifier on the pattern.  It  is  recognized  always.
400           There  may  be  any number of hexadecimal digits inside the braces. The
401           result is from one to six bytes,  encoded  according  to  the  original
402           UTF-8  rules  of  RFC  2279.  This  allows for values in the range 0 to
403           0x7FFFFFFF. Note that not all of those are valid Unicode  code  points,
404           or  indeed  valid  UTF-8 characters according to the later rules in RFC
405           3629.
406    
407    
408    THE ALTERNATIVE MATCHING FUNCTION
409    
410           By  default,  pcretest  uses  the  standard  PCRE  matching   function,
411           pcre_exec() to match each data line. From release 6.0, PCRE supports an
412           alternative matching function, pcre_dfa_test(),  which  operates  in  a
413           different  way,  and has some restrictions. The differences between the
414           two functions are described in the pcrematching documentation.
415    
416           If a data line contains the \D escape sequence, or if the command  line
417           contains  the -dfa option, the alternative matching function is called.
418           This function finds all possible matches at a given point. If, however,
419           the  \F escape sequence is present in the data line, it stops after the
420           first match is found. This is always the shortest possible match.
421    
422    
423    DEFAULT OUTPUT FROM PCRETEST
424    
425           This section describes the output when the  normal  matching  function,
426           pcre_exec(), is being used.
427    
428           When a match succeeds, pcretest outputs the list of captured substrings
429           that pcre_exec() returns, starting with number 0 for  the  string  that
430           matched  the  whole  pattern. Otherwise, it outputs "No match" when the
431           return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
432           tially  matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
433           For any other returns, it outputs the PCRE negative error number.  Here
434           is an example of an interactive pcretest run.
435    
436             $ pcretest
437             PCRE version 7.0 30-Nov-2006
438    
439               re> /^abc(\d+)/
440             data> abc123
441              0: abc123
442              1: 123
443             data> xyz
444             No match
445    
446           Note  that unset capturing substrings that are not followed by one that
447           is set are not returned by pcre_exec(), and are not shown by  pcretest.
448           In  the following example, there are two capturing substrings, but when
449           the first data line is matched, the  second,  unset  substring  is  not
450           shown.  An "internal" unset substring is shown as "<unset>", as for the
451           second data line.
452    
453               re> /(a)|(b)/
454             data> a
455              0: a
456              1: a
457             data> b
458              0: b
459              1: <unset>
460              2: b
461    
462           If the strings contain any non-printing characters, they are output  as
463           \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
464           the pattern. See below for the definition of  non-printing  characters.
465           If  the pattern has the /+ modifier, the output for substring 0 is fol-
466           lowed by the the rest of the subject string, identified  by  "0+"  like
467           this:
468    
469               re> /cat/+
470             data> cataract
471              0: cat
472              0+ aract
473    
474           If  the  pattern  has  the /g or /G modifier, the results of successive
475           matching attempts are output in sequence, like this:
476    
477               re> /\Bi(\w\w)/g
478             data> Mississippi
479              0: iss
480              1: ss
481              0: iss
482              1: ss
483              0: ipp
484              1: pp
485    
486           "No match" is output only if the first match attempt fails.
487    
488           If any of the sequences \C, \G, or \L are present in a data  line  that
489           is  successfully  matched,  the substrings extracted by the convenience
490           functions are output with C, G, or L after the string number instead of
491           a colon. This is in addition to the normal full list. The string length
492           (that is, the return from the extraction function) is given  in  paren-
493           theses after each string for \C and \G.
494    
495           Note that whereas patterns can be continued over several lines (a plain
496           ">" prompt is used for continuations), data lines may not. However new-
497           lines  can  be included in data by means of the \n escape (or \r, \r\n,
498           etc., depending on the newline sequence setting).
499    
500    
501    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
502    
503           When the alternative matching function, pcre_dfa_exec(),  is  used  (by
504           means  of  the \D escape sequence or the -dfa command line option), the
505           output consists of a list of all the matches that start  at  the  first
506           point in the subject where there is at least one match. For example:
507    
508               re> /(tang|tangerine|tan)/
509             data> yellow tangerine\D
510              0: tangerine
511              1: tang
512              2: tan
513    
514           (Using  the  normal  matching function on this data finds only "tang".)
515           The longest matching string is always given first (and numbered  zero).
516           After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
517           lowed by the partially matching substring.
518    
519           If /g is present on the pattern, the search for further matches resumes
520           at the end of the longest match. For example:
521    
522               re> /(tang|tangerine|tan)/g
523             data> yellow tangerine and tangy sultana\D
524              0: tangerine
525              1: tang
526              2: tan
527              0: tang
528              1: tan
529              0: tan
530    
531           Since  the  matching  function  does not support substring capture, the
532           escape sequences that are concerned with captured  substrings  are  not
533           relevant.
534    
535    
536    RESTARTING AFTER A PARTIAL MATCH
537    
538           When the alternative matching function has given the PCRE_ERROR_PARTIAL
539           return, indicating that the subject partially matched the pattern,  you
540           can  restart  the match with additional subject data by means of the \R
541           escape sequence. For example:
542    
543               re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
544             data> 23ja\P\D
545             Partial match: 23ja
546             data> n05\R\D
547              0: n05
548    
549           For further information about partial  matching,  see  the  pcrepartial
550           documentation.
551    
552    
553    CALLOUTS
554    
555           If  the pattern contains any callout requests, pcretest's callout func-
556           tion is called during matching. This works  with  both  matching  func-
557           tions. By default, the called function displays the callout number, the
558           start and current positions in the text at the callout  time,  and  the
559           next pattern item to be tested. For example, the output
560    
561             --->pqrabcdef
562               0    ^  ^     \d
563    
564           indicates  that  callout number 0 occurred for a match attempt starting
565           at the fourth character of the subject string, when the pointer was  at
566           the  seventh  character of the data, and when the next pattern item was
567           \d. Just one circumflex is output if the start  and  current  positions
568           are the same.
569    
570           Callouts numbered 255 are assumed to be automatic callouts, inserted as
571           a result of the /C pattern modifier. In this case, instead  of  showing
572           the  callout  number, the offset in the pattern, preceded by a plus, is
573           output. For example:
574    
575               re> /\d?[A-E]\*/C
576             data> E*
577             --->E*
578              +0 ^      \d?
579              +3 ^      [A-E]
580              +8 ^^     \*
581             +10 ^ ^
582              0: E*
583    
584           The callout function in pcretest returns zero (carry  on  matching)  by
585           default,  but you can use a \C item in a data line (as described above)
586           to change this.
587    
588           Inserting callouts can be helpful when using pcretest to check  compli-
589           cated  regular expressions. For further information about callouts, see
590           the pcrecallout documentation.
591    
592    
593    NON-PRINTING CHARACTERS
594    
595           When pcretest is outputting text in the compiled version of a  pattern,
596           bytes  other  than 32-126 are always treated as non-printing characters
597           are are therefore shown as hex escapes.
598    
599           When pcretest is outputting text that is a matched part  of  a  subject
600           string,  it behaves in the same way, unless a different locale has been
601           set for the  pattern  (using  the  /L  modifier).  In  this  case,  the
602           isprint() function to distinguish printing and non-printing characters.
603    
604    
605    SAVING AND RELOADING COMPILED PATTERNS
606    
607           The  facilities  described  in  this section are not available when the
608           POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
609           ifier is specified.
610    
611           When the POSIX interface is not in use, you can cause pcretest to write
612           a compiled pattern to a file, by following the modifiers with >  and  a
613           file name.  For example:
614    
615             /pattern/im >/some/file
616    
617           See  the pcreprecompile documentation for a discussion about saving and
618           re-using compiled patterns.
619    
620           The data that is written is binary.  The  first  eight  bytes  are  the
621           length  of  the  compiled  pattern  data  followed by the length of the
622           optional study data, each written as four  bytes  in  big-endian  order
623           (most  significant  byte  first). If there is no study data (either the
624           pattern was not studied, or studying did not return any data), the sec-
625           ond  length  is  zero. The lengths are followed by an exact copy of the
626           compiled pattern. If there is additional study data, this follows imme-
627           diately  after  the  compiled pattern. After writing the file, pcretest
628           expects to read a new pattern.
629    
630           A saved pattern can be reloaded into pcretest by specifing < and a file
631           name  instead  of  a pattern. The name of the file must not contain a <
632           character, as otherwise pcretest will interpret the line as  a  pattern
633           delimited by < characters.  For example:
634    
635              re> </some/file
636             Compiled regex loaded from /some/file
637             No study data
638    
639           When  the pattern has been loaded, pcretest proceeds to read data lines
640           in the usual way.
641    
642           You can copy a file written by pcretest to a different host and  reload
643           it  there,  even  if the new host has opposite endianness to the one on
644           which the pattern was compiled. For example, you can compile on an  i86
645           machine and run on a SPARC machine.
646    
647           File  names  for  saving and reloading can be absolute or relative, but
648           note that the shell facility of expanding a file name that starts  with
649           a tilde (~) is not available.
650    
651           The  ability to save and reload files in pcretest is intended for test-
652           ing and experimentation. It is not intended for production use  because
653           only  a  single pattern can be written to a file. Furthermore, there is
654           no facility for supplying  custom  character  tables  for  use  with  a
655           reloaded  pattern.  If  the  original  pattern was compiled with custom
656           tables, an attempt to match a subject string using a  reloaded  pattern
657           is  likely to cause pcretest to crash.  Finally, if you attempt to load
658           a file that is not in the correct format, the result is undefined.
659    
660    
661    SEE ALSO
662    
663           pcre(3), pcreapi(3), pcrecallout(3),  pcrematching(3),  pcrepartial(d),
664           pcrepattern(3), pcreprecompile(3).
665    
666    
667    AUTHOR
668    
669           Philip Hazel
670           University Computing Service
671           Cambridge CB2 3QH, England.
672    
673    
674    REVISION
675    
676           Last updated: 26 March 2010
677           Copyright (c) 1997-2010 University of Cambridge.

Legend:
Removed from v.47  
changed lines
  Added in v.512

  ViewVC Help
Powered by ViewVC 1.1.5