/[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 49 by nigel, Sat Feb 24 21:39:33 2007 UTC revision 227 by ph10, Tue Aug 21 15:00:15 2007 UTC
# Line 1  Line 1 
1  The pcretest program  PCRETEST(1)                                                        PCRETEST(1)
 --------------------  
2    
 This program is intended for testing PCRE, but it can also be used for  
 experimenting with regular expressions.  
3    
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  
6    
   /abc\/  
7    
8  is interpreted as the first line of a pattern that starts with "abc/", causing  SYNOPSIS
9  pcretest to read the next line as a continuation of the regular expression.  
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        Output  the  size  of each compiled pattern after it has been
44                     compiled. This is equivalent to adding  /M  to  each  regular
45                     expression.   For  compatibility  with  earlier  versions  of
46                     pcretest, -s is a synonym for -m.
47    
48           -o osize  Set the number of elements in the output vector that is  used
49                     when  calling pcre_exec() or pcre_dfa_exec() to be osize. The
50                     default value is 45, which is enough for 14 capturing  subex-
51                     pressions   for  pcre_exec()  or  22  different  matches  for
52                     pcre_dfa_exec(). The vector size can be changed for  individ-
53                     ual  matching  calls  by  including  \O in the data line (see
54                     below).
55    
56           -p        Behave as if each regex has the /P modifier; the POSIX  wrap-
57                     per  API  is used to call PCRE. None of the other options has
58                     any effect when -p is set.
59    
60           -q        Do not output the version number of pcretest at the start  of
61                     execution.
62    
63           -S size   On  Unix-like  systems,  set the size of the runtime stack to
64                     size megabytes.
65    
66           -t        Run each compile, study, and match many times with  a  timer,
67                     and  output resulting time per compile or match (in millisec-
68                     onds). Do not set -m with -t, because you will then  get  the
69                     size  output  a  zillion  times,  and the timing will be dis-
70                     torted. You can control the number  of  iterations  that  are
71                     used  for timing by following -t with a number (as a separate
72                     item on the command line). For example, "-t 1000" would iter-
73                     ate 1000 times. The default is to iterate 500000 times.
74    
75           -tm       This is like -t except that it times only the matching phase,
76                     not the compile or study phases.
77    
78    
79    DESCRIPTION
80    
81           If pcretest is given two filename arguments, it reads  from  the  first
82           and writes to the second. If it is given only one filename argument, it
83           reads from that file and writes to stdout.  Otherwise,  it  reads  from
84           stdin  and  writes to stdout, and prompts for each line of input, using
85           "re>" to prompt for regular expressions, and "data>" to prompt for data
86           lines.
87    
88           The program handles any number of sets of input on a single input file.
89           Each set starts with a regular expression, and continues with any  num-
90           ber of data lines to be matched against the pattern.
91    
92           Each  data line is matched separately and independently. If you want to
93           do multi-line matches, you have to use the \n escape sequence (or \r or
94           \r\n, etc., depending on the newline setting) in a single line of input
95           to encode the newline sequences. There is no limit  on  the  length  of
96           data  lines;  the  input  buffer is automatically extended if it is too
97           small.
98    
99           An empty line signals the end of the data lines, at which point  a  new
100           regular  expression is read. The regular expressions are given enclosed
101           in any non-alphanumeric delimiters other than backslash, for example:
102    
103             /(a|bc)x+yz/
104    
105           White space before the initial delimiter is ignored. A regular  expres-
106           sion  may be continued over several input lines, in which case the new-
107           line characters are included within it. It is possible to  include  the
108           delimiter within the pattern by escaping it, for example
109    
110             /abc\/def/
111    
112           If  you  do  so, the escape and the delimiter form part of the pattern,
113           but since delimiters are always non-alphanumeric, this does not  affect
114           its  interpretation.   If the terminating delimiter is immediately fol-
115           lowed by a backslash, for example,
116    
117             /abc/\
118    
119           then a backslash is added to the end of the pattern. This  is  done  to
120           provide  a  way of testing the error condition that arises if a pattern
121           finishes with a backslash, because
122    
123             /abc\/
124    
125           is interpreted as the first line of a pattern that starts with  "abc/",
126           causing pcretest to read the next line as a continuation of the regular
127           expression.
128    
129    
130  PATTERN MODIFIERS  PATTERN MODIFIERS
 -----------------  
131    
132  The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,         A pattern may be followed by any number of modifiers, which are  mostly
133  PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For         single  characters.  Following  Perl usage, these are referred to below
134  example:         as, for example, "the /i modifier", even though the  delimiter  of  the
135           pattern  need  not always be a slash, and no slash is used when writing
136    /caseless/i         modifiers. Whitespace may appear between the  final  pattern  delimiter
137           and the first modifier, and between the modifiers themselves.
138  These modifier letters have the same effect as they do in Perl. There are  
139  others which set PCRE options that do not correspond to anything in Perl: /A,         The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
140  /E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.         PCRE_DOTALL, or PCRE_EXTENDED  options,  respectively,  when  pcre_com-
141           pile()  is  called. These four modifier letters have the same effect as
142  Searching for all possible matches within each subject string can be requested         they do in Perl. For example:
143  by the /g or /G modifier. After finding a match, PCRE is called again to search  
144  the remainder of the subject string. The difference between /g and /G is that           /caseless/i
145  the former uses the startoffset argument to pcre_exec() to start searching at  
146  a new point within the entire string (which is in effect what Perl does),         The following table shows additional modifiers for setting PCRE options
147  whereas the latter passes over a shortened substring. This makes a difference         that do not correspond to anything in Perl:
148  to the matching process if the pattern begins with a lookbehind assertion  
149  (including \b or \B).           /A          PCRE_ANCHORED
150             /C          PCRE_AUTO_CALLOUT
151  If any call to pcre_exec() in a /g or /G sequence matches an empty string, the           /E          PCRE_DOLLAR_ENDONLY
152  next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED flags set in order           /f          PCRE_FIRSTLINE
153  to search for another, non-empty, match at the same point. If this second match           /J          PCRE_DUPNAMES
154  fails, the start offset is advanced by one, and the normal match is retried.           /N          PCRE_NO_AUTO_CAPTURE
155  This imitates the way Perl handles such cases when using the /g modifier or the           /U          PCRE_UNGREEDY
156  split() function.           /X          PCRE_EXTRA
157             /<cr>       PCRE_NEWLINE_CR
158  There are a number of other modifiers for controlling the way pcretest           /<lf>       PCRE_NEWLINE_LF
159  operates.           /<crlf>     PCRE_NEWLINE_CRLF
160             /<anycrlf>  PCRE_NEWLINE_ANYCRLF
161  The /+ modifier requests that as well as outputting the substring that matched           /<any>      PCRE_NEWLINE_ANY
162  the entire pattern, pcretest should in addition output the remainder of the  
163  subject string. This is useful for tests where the subject contains multiple         Those  specifying  line  ending sequences are literal strings as shown,
164  copies of the same substring.         but the letters can be in either  case.  This  example  sets  multiline
165           matching with CRLF as the line ending sequence:
166  The /L modifier must be followed directly by the name of a locale, for example,  
167             /^abc/m<crlf>
168    /pattern/Lfr  
169           Details  of the meanings of these PCRE options are given in the pcreapi
170  For this reason, it must be the last modifier letter. The given locale is set,         documentation.
171  pcre_maketables() is called to build a set of character tables for the locale,  
172  and this is then passed to pcre_compile() when compiling the regular     Finding all matches in a string
173  expression. Without an /L modifier, NULL is passed as the tables pointer; that  
174  is, /L applies only to the expression on which it appears.         Searching for all possible matches within each subject  string  can  be
175           requested  by  the  /g  or  /G modifier. After finding a match, PCRE is
176  The /I modifier requests that pcretest output information about the compiled         called again to search the remainder of the subject string. The differ-
177  expression (whether it is anchored, has a fixed first character, and so on). It         ence between /g and /G is that the former uses the startoffset argument
178  does this by calling pcre_fullinfo() after compiling an expression, and         to pcre_exec() to start searching at a  new  point  within  the  entire
179  outputting the information it gets back. If the pattern is studied, the results         string  (which  is in effect what Perl does), whereas the latter passes
180  of that are also output.         over a shortened substring. This makes a  difference  to  the  matching
181           process if the pattern begins with a lookbehind assertion (including \b
182  The /D modifier is a PCRE debugging feature, which also assumes /I. It causes         or \B).
183  the internal form of compiled regular expressions to be output after  
184  compilation.         If any call to pcre_exec() in a /g or  /G  sequence  matches  an  empty
185           string,  the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
186  The /S modifier causes pcre_study() to be called after the expression has been         flags set in order to search for another, non-empty, match at the  same
187  compiled, and the results used when the expression is matched.         point.   If  this  second  match fails, the start offset is advanced by
188           one, and the normal match is retried. This imitates the way  Perl  han-
189  The /M modifier causes the size of memory block used to hold the compiled         dles such cases when using the /g modifier or the split() function.
190  pattern to be output.  
191       Other modifiers
192  The /P modifier causes pcretest to call PCRE via the POSIX wrapper API rather  
193  than its native API. When this is done, all other modifiers except /i, /m, and         There are yet more modifiers for controlling the way pcretest operates.
194  /+ are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is set if /m  
195  is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always, and         The /+ modifier requests that as well as outputting the substring  that
196  PCRE_DOTALL unless REG_NEWLINE is set.         matched  the  entire  pattern,  pcretest  should in addition output the
197           remainder of the subject string. This is useful  for  tests  where  the
198  The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option set.         subject contains multiple copies of the same substring.
199  This turns on the (currently incomplete) support for UTF-8 character handling  
200  in PCRE, provided that it was compiled with this support enabled. This modifier         The  /B modifier is a debugging feature. It requests that pcretest out-
201  also causes any non-printing characters in output strings to be printed using         put a representation of the compiled byte code after compilation.  Nor-
202  the \x{hh...} notation if they are valid UTF-8 sequences.         mally  this  information contains length and offset values; however, if
203           /Z is also present, this data is replaced by spaces. This is a  special
204           feature for use in the automatic test scripts; it ensures that the same
205           output is generated for different internal link sizes.
206    
207           The /L modifier must be followed directly by the name of a locale,  for
208           example,
209    
210             /pattern/Lfr_FR
211    
212           For this reason, it must be the last modifier. The given locale is set,
213           pcre_maketables() is called to build a set of character tables for  the
214           locale,  and  this  is then passed to pcre_compile() when compiling the
215           regular expression. Without an /L  modifier,  NULL  is  passed  as  the
216           tables  pointer; that is, /L applies only to the expression on which it
217           appears.
218    
219           The /I modifier requests that pcretest  output  information  about  the
220           compiled  pattern (whether it is anchored, has a fixed first character,
221           and so on). It does this by calling pcre_fullinfo() after  compiling  a
222           pattern.  If  the pattern is studied, the results of that are also out-
223           put.
224    
225           The /D modifier is a PCRE debugging feature, and is equivalent to  /BI,
226           that is, both the /B and the /I modifiers.
227    
228           The /F modifier causes pcretest to flip the byte order of the fields in
229           the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This
230           facility  is  for testing the feature in PCRE that allows it to execute
231           patterns that were compiled on a host with a different endianness. This
232           feature  is  not  available  when  the POSIX interface to PCRE is being
233           used, that is, when the /P pattern modifier is specified. See also  the
234           section about saving and reloading compiled patterns below.
235    
236           The  /S  modifier causes pcre_study() to be called after the expression
237           has been compiled, and the results used when the expression is matched.
238    
239           The  /M  modifier causes the size of memory block used to hold the com-
240           piled pattern to be output.
241    
242           The /P modifier causes pcretest to call PCRE via the POSIX wrapper  API
243           rather  than  its  native  API.  When this is done, all other modifiers
244           except /i, /m, and /+ are ignored. REG_ICASE is set if /i  is  present,
245           and  REG_NEWLINE  is  set if /m is present. The wrapper functions force
246           PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is  set.
247    
248           The  /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
249           set. This turns on support for UTF-8 character handling in  PCRE,  pro-
250           vided  that  it  was  compiled with this support enabled. This modifier
251           also causes any non-printing characters in output strings to be printed
252           using the \x{hh...} notation if they are valid UTF-8 sequences.
253    
254           If  the  /?  modifier  is  used  with  /8,  it  causes pcretest to call
255           pcre_compile() with the  PCRE_NO_UTF8_CHECK  option,  to  suppress  the
256           checking of the string for UTF-8 validity.
257    
258    
259  DATA LINES  DATA LINES
 ----------  
260    
261  Before each data line is passed to pcre_exec(), leading and trailing whitespace         Before  each  data  line is passed to pcre_exec(), leading and trailing
262  is removed, and it is then scanned for \ escapes. The following are recognized:         whitespace is removed, and it is then scanned for \  escapes.  Some  of
263           these  are  pretty esoteric features, intended for checking out some of
264           the more complicated features of PCRE. If you are just  testing  "ordi-
265           nary"  regular  expressions,  you probably don't need any of these. The
266           following escapes are recognized:
267    
268             \a         alarm (BEL, \x07)
269             \b         backspace (\x08)
270             \e         escape (\x27)
271             \f         formfeed (\x0c)
272             \n         newline (\x0a)
273             \qdd       set the PCRE_MATCH_LIMIT limit to dd
274                          (any number of digits)
275             \r         carriage return (\x0d)
276             \t         tab (\x09)
277             \v         vertical tab (\x0b)
278             \nnn       octal character (up to 3 octal digits)
279             \xhh       hexadecimal character (up to 2 hex digits)
280             \x{hh...}  hexadecimal character, any number of digits
281                          in UTF-8 mode
282             \A         pass the PCRE_ANCHORED option to pcre_exec()
283                          or pcre_dfa_exec()
284             \B         pass the PCRE_NOTBOL option to pcre_exec()
285                          or pcre_dfa_exec()
286             \Cdd       call pcre_copy_substring() for substring dd
287                          after a successful match (number less than 32)
288             \Cname     call pcre_copy_named_substring() for substring
289                          "name" after a successful match (name termin-
290                          ated by next non alphanumeric character)
291             \C+        show the current captured substrings at callout
292                          time
293             \C-        do not supply a callout function
294             \C!n       return 1 instead of 0 when callout number n is
295                          reached
296             \C!n!m     return 1 instead of 0 when callout number n is
297                          reached for the nth time
298             \C*n       pass the number n (may be negative) as callout
299                          data; this is used as the callout return value
300             \D         use the pcre_dfa_exec() match function
301             \F         only shortest match for pcre_dfa_exec()
302             \Gdd       call pcre_get_substring() for substring dd
303                          after a successful match (number less than 32)
304             \Gname     call pcre_get_named_substring() for substring
305                          "name" after a successful match (name termin-
306                          ated by next non-alphanumeric character)
307             \L         call pcre_get_substringlist() after a
308                          successful match
309             \M         discover the minimum MATCH_LIMIT and
310                          MATCH_LIMIT_RECURSION settings
311             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
312                          or pcre_dfa_exec()
313             \Odd       set the size of the output vector passed to
314                          pcre_exec() to dd (any number of digits)
315             \P         pass the PCRE_PARTIAL option to pcre_exec()
316                          or pcre_dfa_exec()
317             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
318                          (any number of digits)
319             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
320             \S         output details of memory get/free calls during matching
321             \Z         pass the PCRE_NOTEOL option to pcre_exec()
322                          or pcre_dfa_exec()
323             \?         pass the PCRE_NO_UTF8_CHECK option to
324                          pcre_exec() or pcre_dfa_exec()
325             \>dd       start the match at offset dd (any number of digits);
326                          this sets the startoffset argument for pcre_exec()
327                          or pcre_dfa_exec()
328             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
329                          or pcre_dfa_exec()
330             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
331                          or pcre_dfa_exec()
332             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
333                          or pcre_dfa_exec()
334             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
335                          or pcre_dfa_exec()
336             \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()
337                          or pcre_dfa_exec()
338    
339           The escapes that specify line ending  sequences  are  literal  strings,
340           exactly as shown. No more than one newline setting should be present in
341           any data line.
342    
343           A backslash followed by anything else just escapes the  anything  else.
344           If  the very last character is a backslash, it is ignored. This gives a
345           way of passing an empty line as data, since a real  empty  line  termi-
346           nates the data input.
347    
348           If  \M  is present, pcretest calls pcre_exec() several times, with dif-
349           ferent values in the match_limit and  match_limit_recursion  fields  of
350           the  pcre_extra  data structure, until it finds the minimum numbers for
351           each parameter that allow pcre_exec() to complete. The match_limit num-
352           ber  is  a  measure of the amount of backtracking that takes place, and
353           checking it out can be instructive. For most simple matches, the number
354           is  quite  small,  but for patterns with very large numbers of matching
355           possibilities, it can become large very quickly with increasing  length
356           of subject string. The match_limit_recursion number is a measure of how
357           much stack (or, if PCRE is compiled with  NO_RECURSE,  how  much  heap)
358           memory is needed to complete the match attempt.
359    
360           When  \O  is  used, the value specified may be higher or lower than the
361           size set by the -O command line option (or defaulted to 45); \O applies
362           only to the call of pcre_exec() for the line in which it appears.
363    
364           If  the /P modifier was present on the pattern, causing the POSIX wrap-
365           per API to be used, the only option-setting  sequences  that  have  any
366           effect  are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
367           to be passed to regexec().
368    
369           The use of \x{hh...} to represent UTF-8 characters is not dependent  on
370           the  use  of  the  /8 modifier on the pattern. It is recognized always.
371           There may be any number of hexadecimal digits inside  the  braces.  The
372           result  is  from  one  to  six bytes, encoded according to the original
373           UTF-8 rules of RFC 2279. This allows for  values  in  the  range  0  to
374           0x7FFFFFFF.  Note  that not all of those are valid Unicode code points,
375           or indeed valid UTF-8 characters according to the later  rules  in  RFC
376           3629.
377    
378    
379    THE ALTERNATIVE MATCHING FUNCTION
380    
381           By   default,  pcretest  uses  the  standard  PCRE  matching  function,
382           pcre_exec() to match each data line. From release 6.0, PCRE supports an
383           alternative  matching  function,  pcre_dfa_test(),  which operates in a
384           different way, and has some restrictions. The differences  between  the
385           two functions are described in the pcrematching documentation.
386    
387           If  a data line contains the \D escape sequence, or if the command line
388           contains the -dfa option, the alternative matching function is  called.
389           This function finds all possible matches at a given point. If, however,
390           the \F escape sequence is present in the data line, it stops after  the
391           first match is found. This is always the shortest possible match.
392    
393    
394    DEFAULT OUTPUT FROM PCRETEST
395    
396           This  section  describes  the output when the normal matching function,
397           pcre_exec(), is being used.
398    
399           When a match succeeds, pcretest outputs the list of captured substrings
400           that  pcre_exec()  returns,  starting with number 0 for the string that
401           matched the whole pattern. Otherwise, it outputs "No match" or "Partial
402           match"  when  pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
403           TIAL, respectively, and otherwise the PCRE negative error number.  Here
404           is an example of an interactive pcretest run.
405    
406             $ pcretest
407             PCRE version 7.0 30-Nov-2006
408    
409               re> /^abc(\d+)/
410             data> abc123
411              0: abc123
412              1: 123
413             data> xyz
414             No match
415    
416           If  the strings contain any non-printing characters, they are output as
417           \0x escapes, or as \x{...} escapes if the /8 modifier  was  present  on
418           the  pattern.  See below for the definition of non-printing characters.
419           If the pattern has the /+ modifier, the output for substring 0 is  fol-
420           lowed  by  the  the rest of the subject string, identified by "0+" like
421           this:
422    
423               re> /cat/+
424             data> cataract
425              0: cat
426              0+ aract
427    
428           If the pattern has the /g or /G modifier,  the  results  of  successive
429           matching attempts are output in sequence, like this:
430    
431               re> /\Bi(\w\w)/g
432             data> Mississippi
433              0: iss
434              1: ss
435              0: iss
436              1: ss
437              0: ipp
438              1: pp
439    
440           "No match" is output only if the first match attempt fails.
441    
442           If  any  of the sequences \C, \G, or \L are present in a data line that
443           is successfully matched, the substrings extracted  by  the  convenience
444           functions are output with C, G, or L after the string number instead of
445           a colon. This is in addition to the normal full list. The string length
446           (that  is,  the return from the extraction function) is given in paren-
447           theses after each string for \C and \G.
448    
449           Note that whereas patterns can be continued over several lines (a plain
450           ">" prompt is used for continuations), data lines may not. However new-
451           lines can be included in data by means of the \n escape (or  \r,  \r\n,
452           etc., depending on the newline sequence setting).
453    
454    
455    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
456    
457           When  the  alternative  matching function, pcre_dfa_exec(), is used (by
458           means of the \D escape sequence or the -dfa command line  option),  the
459           output  consists  of  a list of all the matches that start at the first
460           point in the subject where there is at least one match. For example:
461    
462               re> /(tang|tangerine|tan)/
463             data> yellow tangerine\D
464              0: tangerine
465              1: tang
466              2: tan
467    
468           (Using the normal matching function on this data  finds  only  "tang".)
469           The  longest matching string is always given first (and numbered zero).
470    
471           If /g is present on the pattern, the search for further matches resumes
472           at the end of the longest match. For example:
473    
474               re> /(tang|tangerine|tan)/g
475             data> yellow tangerine and tangy sultana\D
476              0: tangerine
477              1: tang
478              2: tan
479              0: tang
480              1: tan
481              0: tan
482    
483           Since  the  matching  function  does not support substring capture, the
484           escape sequences that are concerned with captured  substrings  are  not
485           relevant.
486    
487    
488    RESTARTING AFTER A PARTIAL MATCH
489    
490           When the alternative matching function has given the PCRE_ERROR_PARTIAL
491           return, indicating that the subject partially matched the pattern,  you
492           can  restart  the match with additional subject data by means of the \R
493           escape sequence. For example:
494    
495               re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
496             data> 23ja\P\D
497             Partial match: 23ja
498             data> n05\R\D
499              0: n05
500    
501           For further information about partial  matching,  see  the  pcrepartial
502           documentation.
503    
504    
505    CALLOUTS
506    
507           If  the pattern contains any callout requests, pcretest's callout func-
508           tion is called during matching. This works  with  both  matching  func-
509           tions. By default, the called function displays the callout number, the
510           start and current positions in the text at the callout  time,  and  the
511           next pattern item to be tested. For example, the output
512    
513             --->pqrabcdef
514               0    ^  ^     \d
515    
516           indicates  that  callout number 0 occurred for a match attempt starting
517           at the fourth character of the subject string, when the pointer was  at
518           the  seventh  character of the data, and when the next pattern item was
519           \d. Just one circumflex is output if the start  and  current  positions
520           are the same.
521    
522           Callouts numbered 255 are assumed to be automatic callouts, inserted as
523           a result of the /C pattern modifier. In this case, instead  of  showing
524           the  callout  number, the offset in the pattern, preceded by a plus, is
525           output. For example:
526    
527               re> /\d?[A-E]\*/C
528             data> E*
529             --->E*
530              +0 ^      \d?
531              +3 ^      [A-E]
532              +8 ^^     \*
533             +10 ^ ^
534              0: E*
535    
536           The callout function in pcretest returns zero (carry  on  matching)  by
537           default,  but you can use a \C item in a data line (as described above)
538           to change this.
539    
540           Inserting callouts can be helpful when using pcretest to check  compli-
541           cated  regular expressions. For further information about callouts, see
542           the pcrecallout documentation.
543    
544    
545    NON-PRINTING CHARACTERS
546    
547           When pcretest is outputting text in the compiled version of a  pattern,
548           bytes  other  than 32-126 are always treated as non-printing characters
549           are are therefore shown as hex escapes.
550    
551           When pcretest is outputting text that is a matched part  of  a  subject
552           string,  it behaves in the same way, unless a different locale has been
553           set for the  pattern  (using  the  /L  modifier).  In  this  case,  the
554           isprint() function to distinguish printing and non-printing characters.
555    
556    
557    SAVING AND RELOADING COMPILED PATTERNS
558    
559           The facilities described in this section are  not  available  when  the
560           POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
561           ifier is specified.
562    
563           When the POSIX interface is not in use, you can cause pcretest to write
564           a  compiled  pattern to a file, by following the modifiers with > and a
565           file name.  For example:
566    
567             /pattern/im >/some/file
568    
569           See the pcreprecompile documentation for a discussion about saving  and
570           re-using compiled patterns.
571    
572           The  data  that  is  written  is  binary. The first eight bytes are the
573           length of the compiled pattern data  followed  by  the  length  of  the
574           optional  study  data,  each  written as four bytes in big-endian order
575           (most significant byte first). If there is no study  data  (either  the
576           pattern was not studied, or studying did not return any data), the sec-
577           ond length is zero. The lengths are followed by an exact  copy  of  the
578           compiled pattern. If there is additional study data, this follows imme-
579           diately after the compiled pattern. After writing  the  file,  pcretest
580           expects to read a new pattern.
581    
582           A saved pattern can be reloaded into pcretest by specifing < and a file
583           name instead of a pattern. The name of the file must not  contain  a  <
584           character,  as  otherwise pcretest will interpret the line as a pattern
585           delimited by < characters.  For example:
586    
587              re> </some/file
588             Compiled regex loaded from /some/file
589             No study data
590    
591           When the pattern has been loaded, pcretest proceeds to read data  lines
592           in the usual way.
593    
594           You  can copy a file written by pcretest to a different host and reload
595           it there, even if the new host has opposite endianness to  the  one  on
596           which  the pattern was compiled. For example, you can compile on an i86
597           machine and run on a SPARC machine.
598    
599           File names for saving and reloading can be absolute  or  relative,  but
600           note  that the shell facility of expanding a file name that starts with
601           a tilde (~) is not available.
602    
603           The ability to save and reload files in pcretest is intended for  test-
604           ing  and experimentation. It is not intended for production use because
605           only a single pattern can be written to a file. Furthermore,  there  is
606           no  facility  for  supplying  custom  character  tables  for use with a
607           reloaded pattern. If the original  pattern  was  compiled  with  custom
608           tables,  an  attempt to match a subject string using a reloaded pattern
609           is likely to cause pcretest to crash.  Finally, if you attempt to  load
610           a file that is not in the correct format, the result is undefined.
611    
612    
613    SEE ALSO
614    
615           pcre(3),  pcreapi(3),  pcrecallout(3), pcrematching(3), pcrepartial(d),
616           pcrepattern(3), pcreprecompile(3).
617    
618    
619    AUTHOR
620    
621           Philip Hazel
622           University Computing Service
623           Cambridge CB2 3QH, England.
624    
625    
626    \a         alarm (= BEL)  REVISION
   \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)  
   \x{hh...}  hexadecimal UTF-8 character  
   
   \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.  
   
 The use of \x{hh...} to represent UTF-8 characters is not dependent on the use  
 of the /8 modifier on the pattern. It is recognized always. There may be any  
 number of hexadecimal digits inside the braces. The result is from one to six  
 bytes, encoded according to the UTF-8 rules.  
   
   
 OUTPUT FROM PCRETEST  
 --------------------  
   
 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, or as \x{...} escapes if the /8 modifier was present on the pattern.  
 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.  
   
   
 COMMAND LINE OPTIONS  
 --------------------  
   
 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 -m, 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  
627    
628  Philip Hazel <ph10@cam.ac.uk>         Last updated: 21 August 2007
629  August 2000         Copyright (c) 1997-2007 University of Cambridge.

Legend:
Removed from v.49  
changed lines
  Added in v.227

webmaster@exim.org
ViewVC Help
Powered by ViewVC 1.1.12