/[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 71 by nigel, Sat Feb 24 21:40:24 2007 UTC revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC
# Line 1  Line 1 
1    PCRETEST(1)                                                        PCRETEST(1)
2    
3    
4  NAME  NAME
5       pcretest - a program  for  testing  Perl-compatible  regular         pcretest - a program for testing Perl-compatible regular expressions.
      expressions.  
6    
7    
8  SYNOPSIS  SYNOPSIS
      pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [source]  [des-  
      tination]  
9    
10       pcretest was written as a test program for the PCRE  regular         pcretest [options] [source] [destination]
      expression  library  itself,  but  it  can  also be used for  
      experimenting  with  regular  expressions.   This   document  
      describes  the  features of the test program; for details of  
      the regular  expressions  themselves,  see  the  pcrepattern  
      documentation.  For details of PCRE and its options, see the  
      pcreapi documentation.  
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    
 OPTIONS  
19    
20    OPTIONS
21    
22       -C        Output the version number of the PCRE library, and         -C        Output the version number of the PCRE library, and all avail-
23                 all   available  information  about  the  optional                   able   information  about  the  optional  features  that  are
24                 features that are included, and then exit.                   included, and then exit.
25    
26       -d        Behave as if each regex had the /D  modifier  (see         -d        Behave as if each regex has  the  /D  (debug)  modifier;  the
27                 below); the internal form is output after compila-                   internal form is output after compilation.
28                 tion.  
29           -dfa      Behave  as if each data line contains the \D escape sequence;
30       -i        Behave as if  each  regex  had  the  /I  modifier;                   this    causes    the    alternative    matching    function,
31                 information  about  the  compiled pattern is given                   pcre_dfa_exec(),   to   be   used  instead  of  the  standard
32                 after compilation.                   pcre_exec() function (more detail is given below).
33    
34       -m        Output the size of each compiled pattern after  it         -i        Behave as if each regex  has  the  /I  modifier;  information
35                 has been compiled. This is equivalent to adding /M                   about the compiled pattern is given after compilation.
36                 to each regular expression. For compatibility with  
37                 earlier  versions of pcretest, -s is a synonym for         -m        Output  the  size  of each compiled pattern after it has been
38                 -m.                   compiled. This is equivalent to adding  /M  to  each  regular
39                     expression.   For  compatibility  with  earlier  versions  of
40       -o osize  Set the number of elements in  the  output  vector                   pcretest, -s is a synonym for -m.
41                 that  is  used  when calling PCRE to be osize. The  
42                 default value is 45, which is enough for  14  cap-         -o osize  Set the number of elements in the output vector that is  used
43                 turing  subexpressions.  The  vector  size  can be                   when  calling  pcre_exec()  to be osize. The default value is
44                 changed for individual matching calls by including                   45, which is enough for 14 capturing subexpressions. The vec-
45                 \O in the data line (see below).                   tor  size  can  be  changed  for individual matching calls by
46                     including \O in the data line (see below).
47       -p        Behave as if each regex has /P modifier; the POSIX  
48                 wrapper  API  is  used  to  call PCRE. None of the         -p        Behave as if each regex has the /P modifier; the POSIX  wrap-
49                 other options has any effect when -p is set.                   per  API  is used to call PCRE. None of the other options has
50                     any effect when -p is set.
51       -t        Run each compile, study, and match many times with  
52                 a  timer, and output resulting time per compile or         -q        Do not output the version number of pcretest at the start  of
53                 match (in milliseconds). Do not set  -t  with  -m,                   execution.
54                 because  you  will  then get the size output 20000  
55                 times and the timing will be distorted.         -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  DESCRIPTION
66    
67       If pcretest is given two filename arguments, it  reads  from         If pcretest is given two filename arguments, it reads  from  the  first
68       the  first and writes to the second. If it is given only one         and writes to the second. If it is given only one filename argument, it
69       filename argument, it reads from that  file  and  writes  to         reads from that file and writes to stdout.  Otherwise,  it  reads  from
70       stdout. Otherwise, it reads from stdin and writes to stdout,         stdin  and  writes to stdout, and prompts for each line of input, using
71       and prompts for each line of input, using  "re>"  to  prompt         "re>" to prompt for regular expressions, and "data>" to prompt for data
72       for  regular  expressions,  and  "data>"  to prompt for data         lines.
73       lines.  
74           The program handles any number of sets of input on a single input file.
75       The program handles any number of sets of input on a  single         Each set starts with a regular expression, and continues with any  num-
76       input  file.  Each set starts with a regular expression, and         ber of data lines to be matched against the pattern.
77       continues with any  number  of  data  lines  to  be  matched  
78       against the pattern.         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       Each line is matched separately and  independently.  If  you         \r\n,  depending  on  the newline setting) in a single line of input to
81       want  to  do  multiple-line  matches, you have to use the \n         encode the newline characters. There is no limit on the length of  data
82       escape sequence in a single line of input to encode the new-         lines; the input buffer is automatically extended if it is too small.
83       line  characters.  The maximum length of data line is 30,000  
84       characters.         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       An empty line signals the end of the data  lines,  at  which         in any non-alphanumeric delimiters other than backslash, for example:
87       point  a new regular expression is read. The regular expres-  
88       sions are given enclosed in  any  non-alphameric  delimiters           /(a|bc)x+yz/
89       other than backslash, for example  
90           White  space before the initial delimiter is ignored. A regular expres-
91         /(a|bc)x+yz/         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       White space before the initial delimiter is ignored. A regu-         delimiter within the pattern by escaping it, for example
94       lar expression may be continued over several input lines, in  
95       which case the newline characters are included within it. It           /abc\/def/
96       is  possible  to include the delimiter within the pattern by  
97       escaping it, for example         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         /abc\/def/         its interpretation.  If the terminating delimiter is  immediately  fol-
100           lowed by a backslash, for example,
101       If you do so, the escape and the delimiter form part of  the  
102       pattern,  but  since  delimiters  are always non-alphameric,           /abc/\
103       this does not affect its interpretation.  If the terminating  
104       delimiter  is immediately followed by a backslash, for exam-         then  a  backslash  is added to the end of the pattern. This is done to
105       ple,         provide a way of testing the error condition that arises if  a  pattern
106           finishes with a backslash, because
107         /abc/\  
108             /abc\/
109       then a backslash is added to the end of the pattern. This is  
110       done  to  provide  a way of testing the error condition that         is  interpreted as the first line of a pattern that starts with "abc/",
111       arises if a pattern finishes with a backslash, because         causing pcretest to read the next line as a continuation of the regular
112           expression.
        /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.  
113    
114    
115  PATTERN MODIFIERS  PATTERN MODIFIERS
116    
117       The pattern may be followed by i, m, s,  or  x  to  set  the         A  pattern may be followed by any number of modifiers, which are mostly
118       PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED         single characters. Following Perl usage, these are  referred  to  below
119       options, respectively. For example:         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         /caseless/i         modifiers.  Whitespace  may  appear between the final pattern delimiter
122           and the first modifier, and between the modifiers themselves.
123       These modifier letters have the same effect as  they  do  in  
124       Perl.  There  are  others  that set PCRE options that do not         The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
125       correspond to anything in Perl:  /A, /E, /N, /U, and /X  set         PCRE_DOTALL,  or  PCRE_EXTENDED  options,  respectively, when pcre_com-
126       PCRE_ANCHORED,   PCRE_DOLLAR_ENDONLY,  PCRE_NO_AUTO_CAPTURE,         pile() is called. These four modifier letters have the same  effect  as
127       PCRE_UNGREEDY, and PCRE_EXTRA respectively.         they do in Perl. For example:
128    
129       Searching for  all  possible  matches  within  each  subject           /caseless/i
130       string  can  be  requested  by  the /g or /G modifier. After  
131       finding  a  match,  PCRE  is  called  again  to  search  the         The following table shows additional modifiers for setting PCRE options
132       remainder  of  the subject string. The difference between /g         that do not correspond to anything in Perl:
133       and /G is that the former uses the startoffset  argument  to  
134       pcre_exec()  to  start  searching  at a new point within the           /A       PCRE_ANCHORED
135       entire string (which is in effect what Perl  does),  whereas           /C       PCRE_AUTO_CALLOUT
136       the  latter  passes over a shortened substring. This makes a           /E       PCRE_DOLLAR_ENDONLY
137       difference to the matching process  if  the  pattern  begins           /f       PCRE_FIRSTLINE
138       with a lookbehind assertion (including \b or \B).           /J       PCRE_DUPNAMES
139             /N       PCRE_NO_AUTO_CAPTURE
140       If any call to pcre_exec() in a /g or /G sequence matches an           /U       PCRE_UNGREEDY
141       empty  string,  the next call is done with the PCRE_NOTEMPTY           /X       PCRE_EXTRA
142       and PCRE_ANCHORED flags set in order to search for  another,           /<cr>    PCRE_NEWLINE_CR
143       non-empty,  match  at  the same point.  If this second match           /<lf>    PCRE_NEWLINE_LF
144       fails, the start offset is advanced by one, and  the  normal           /<crlf>  PCRE_NEWLINE_CRLF
145       match  is  retried.  This imitates the way Perl handles such  
146       cases when using the /g modifier or the split() function.         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       There are a number of other modifiers  for  controlling  the         tion.
149       way pcretest operates.  
150       Finding all matches in a string
151       The /+ modifier requests that as well as outputting the sub-  
152       string  that  matched the entire pattern, pcretest should in         Searching for all possible matches within each subject  string  can  be
153       addition output the remainder of the subject string. This is         requested  by  the  /g  or  /G modifier. After finding a match, PCRE is
154       useful  for tests where the subject contains multiple copies         called again to search the remainder of the subject string. The differ-
155       of the same substring.         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       The /L modifier must be followed directly by the name  of  a         string  (which  is in effect what Perl does), whereas the latter passes
158       locale, for example,         over a shortened substring. This makes a  difference  to  the  matching
159           process if the pattern begins with a lookbehind assertion (including \b
160         /pattern/Lfr         or \B).
161    
162       For this reason, it must be the last  modifier  letter.  The         If any call to pcre_exec() in a /g or  /G  sequence  matches  an  empty
163       given  locale is set, pcre_maketables() is called to build a         string,  the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
164       set of character tables for the locale,  and  this  is  then         flags set in order to search for another, non-empty, match at the  same
165       passed  to pcre_compile() when compiling the regular expres-         point.   If  this  second  match fails, the start offset is advanced by
166       sion. Without an /L modifier, NULL is passed as  the  tables         one, and the normal match is retried. This imitates the way  Perl  han-
167       pointer; that is, /L applies only to the expression on which         dles such cases when using the /g modifier or the split() function.
168       it appears.  
169       Other modifiers
170       The /I modifier requests that  pcretest  output  information  
171       about the compiled expression (whether it is anchored, has a         There are yet more modifiers for controlling the way pcretest operates.
172       fixed first character, and so on). It does this  by  calling  
173       pcre_fullinfo()  after  compiling an expression, and output-         The /+ modifier requests that as well as outputting the substring  that
174       ting the information it gets back. If the  pattern  is  stu-         matched  the  entire  pattern,  pcretest  should in addition output the
175       died, the results of that are also output.         remainder of the subject string. This is useful  for  tests  where  the
176           subject contains multiple copies of the same substring.
177       The /D modifier is a  PCRE  debugging  feature,  which  also  
178       assumes /I.  It causes the internal form of compiled regular         The  /L modifier must be followed directly by the name of a locale, for
179       expressions to be output after compilation. If  the  pattern         example,
180       was studied, the information returned is also output.  
181             /pattern/Lfr_FR
182       The /S modifier causes pcre_study() to be called  after  the  
183       expression  has been compiled, and the results used when the         For this reason, it must be the last modifier. The given locale is set,
184       expression is matched.         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       The /M modifier causes the size of memory block used to hold         regular  expression.  Without  an  /L  modifier,  NULL is passed as the
187       the compiled pattern to be output.         tables pointer; that is, /L applies only to the expression on which  it
188           appears.
189       The /P modifier causes pcretest to call PCRE via  the  POSIX  
190       wrapper  API  rather than its native API. When this is done,         The  /I  modifier  requests  that pcretest output information about the
191       all other modifiers except  /i,  /m,  and  /+  are  ignored.         compiled pattern (whether it is anchored, has a fixed first  character,
192       REG_ICASE is set if /i is present, and REG_NEWLINE is set if         and  so  on). It does this by calling pcre_fullinfo() after compiling a
193       /m    is    present.    The    wrapper    functions    force         pattern. If the pattern is studied, the results of that are  also  out-
194       PCRE_DOLLAR_ENDONLY    always,    and   PCRE_DOTALL   unless         put.
195       REG_NEWLINE is set.  
196           The /D modifier is a PCRE debugging feature, which also assumes /I.  It
197       The /8 modifier  causes  pcretest  to  call  PCRE  with  the         causes the internal form of compiled regular expressions to  be  output
198       PCRE_UTF8  option set. This turns on support for UTF-8 char-         after compilation. If the pattern was studied, the information returned
199       acter handling in PCRE, provided that it was  compiled  with         is also output.
200       this  support  enabled.  This  modifier also causes any non-  
201       printing characters in output strings to  be  printed  using         The /F modifier causes pcretest to flip the byte order of the fields in
202       the \x{hh...} notation if they are valid UTF-8 sequences.         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       If the /? modifier is used with /8, it  causes  pcretest  to         patterns that were compiled on a host with a different endianness. This
205       call  pcre_compile()  with the PCRE_NO_UTF8_CHECK option, to         feature is not available when the POSIX  interface  to  PCRE  is  being
206       suppress the checking of the string for UTF-8 validity.         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  CALLOUTS  DATA LINES
233    
234       If the pattern contains  any  callout  requests,  pcretest's         Before each data line is passed to pcre_exec(),  leading  and  trailing
235       callout function will be called. By default, it displays the         whitespace  is  removed,  and it is then scanned for \ escapes. Some of
236       callout number, and the start and current positions  in  the         these are pretty esoteric features, intended for checking out  some  of
237       text at the callout time. For example, the output         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         --->pqrabcdef         following escapes are recognized:
240           0    ^  ^  
241             \a         alarm (= BEL)
242       indicates that callout number 0 occurred for a match attempt           \b         backspace
243       starting at the fourth character of the subject string, when           \e         escape
244       the pointer was at the seventh character. The callout  func-           \f         formfeed
245       tion returns zero (carry on matching) by default.           \n         newline
246             \qdd       set the PCRE_MATCH_LIMIT limit to dd
247       Inserting callouts may be helpful  when  using  pcretest  to                        (any number of digits)
248       check  complicated regular expressions. For further informa-           \r         carriage return
249       tion about callouts, see the pcrecallout documentation.           \t         tab
250             \v         vertical tab
251       For testing the PCRE library, additional control of  callout           \nnn       octal character (up to 3 octal digits)
252       behaviour  is available via escape sequences in the data, as           \xhh       hexadecimal character (up to 2 hex digits)
253       described in the following section.  In  particular,  it  is           \x{hh...}  hexadecimal character, any number of digits
254       possible to pass in a number as callout data (the default is                        in UTF-8 mode
255       zero). If the callout function receives a  non-zero  number,           \A         pass the PCRE_ANCHORED option to pcre_exec()
256       it returns that value instead of zero.                        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    
 DATA LINES  
465    
466       Before each data line is passed to pcre_exec(), leading  and  CALLOUTS
467       trailing whitespace is removed, and it is then scanned for \  
468       escapes.  Some  of  these  are  pretty  esoteric   features,         If  the pattern contains any callout requests, pcretest's callout func-
469       intended  for  checking  out  some  of  the more complicated         tion is called during matching. This works  with  both  matching  func-
470       features of PCRE. If you are just testing "ordinary" regular         tions. By default, the called function displays the callout number, the
471       expressions,  you probably don't need any of these. The fol-         start and current positions in the text at the callout  time,  and  the
472       lowing escapes are recognized:         next pattern item to be tested. For example, the output
473    
474         \a         alarm (= BEL)           --->pqrabcdef
475         \b         backspace             0    ^  ^     \d
476         \e         escape  
477         \f         formfeed         indicates  that  callout number 0 occurred for a match attempt starting
478         \n         newline         at the fourth character of the subject string, when the pointer was  at
479         \r         carriage return         the  seventh  character of the data, and when the next pattern item was
480         \t         tab         \d. Just one circumflex is output if the start  and  current  positions
481         \v         vertical tab         are the same.
482         \nnn       octal character (up to 3 octal digits)  
483         \xhh       hexadecimal character (up to 2 hex digits)         Callouts numbered 255 are assumed to be automatic callouts, inserted as
484         \x{hh...}  hexadecimal character, any number of digits         a result of the /C pattern modifier. In this case, instead  of  showing
485                      in UTF-8 mode         the  callout  number, the offset in the pattern, preceded by a plus, is
486         \A         pass the PCRE_ANCHORED option to pcre_exec()         output. For example:
487         \B         pass the PCRE_NOTBOL option to pcre_exec()  
488         \Cdd       call pcre_copy_substring() for substring dd             re> /\d?[A-E]\*/C
489                      after a successful match (any decimal number           data> E*
490                      less than 32)           --->E*
491         \Cname     call pcre_copy_named_substring() for substring            +0 ^      \d?
492              +3 ^      [A-E]
493                      "name" after a successful match (name termin-            +8 ^^     \*
494                      ated by next non alphanumeric character)           +10 ^ ^
495         \C+        show the current captured substrings at callout            0: E*
496                      time  
497         \C-        do not supply a callout function         The callout function in pcretest returns zero (carry  on  matching)  by
498         \C!n       return 1 instead of 0 when callout number n is         default,  but you can use a \C item in a data line (as described above)
499                      reached         to change this.
500         \C!n!m     return 1 instead of 0 when callout number n is  
501                      reached for the nth time         Inserting callouts can be helpful when using pcretest to check  compli-
502         \C*n       pass the number n (may be negative) as callout         cated  regular expressions. For further information about callouts, see
503                      data         the pcrecallout documentation.
504         \Gdd       call pcre_get_substring() for substring dd  
505                      after a successful match (any decimal number  
506                      less than 32)  SAVING AND RELOADING COMPILED PATTERNS
507         \Gname     call pcre_get_named_substring() for substring  
508                      "name" after a successful match (name termin-         The facilities described in this section are  not  available  when  the
509                      ated by next non-alphanumeric character)         POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
510         \L         call pcre_get_substringlist() after a         ifier is specified.
511                      successful match  
512         \M         discover the minimum MATCH_LIMIT setting         When the POSIX interface is not in use, you can cause pcretest to write
513         \N         pass the PCRE_NOTEMPTY option to pcre_exec()         a  compiled  pattern to a file, by following the modifiers with > and a
514         \Odd       set the size of the output vector passed to         file name.  For example:
515                      pcre_exec() to dd (any number of decimal  
516                      digits)           /pattern/im >/some/file
517         \Z         pass the PCRE_NOTEOL option to pcre_exec()  
518         \?         pass the PCRE_NO_UTF8_CHECK option to         See the pcreprecompile documentation for a discussion about saving  and
519                      pcre_exec()         re-using compiled patterns.
520    
521       If \M is present, pcretest calls pcre_exec() several  times,         The  data  that  is  written  is  binary. The first eight bytes are the
522       with  different  values  in  the  match_limit  field  of the         length of the compiled pattern data  followed  by  the  length  of  the
523       pcre_extra data structure, until it finds the minimum number         optional  study  data,  each  written as four bytes in big-endian order
524       that is needed for pcre_exec() to complete. This number is a         (most significant byte first). If there is no study  data  (either  the
525       measure of the amount of  recursion  and  backtracking  that         pattern was not studied, or studying did not return any data), the sec-
526       takes  place,  and  checking  it out can be instructive. For         ond length is zero. The lengths are followed by an exact  copy  of  the
527       most simple matches, the number is quite small, but for pat-         compiled pattern. If there is additional study data, this follows imme-
528       terns  with very large numbers of matching possibilities, it         diately after the compiled pattern. After writing  the  file,  pcretest
529       can become large very quickly with increasing length of sub-         expects to read a new pattern.
530       ject string.  
531           A saved pattern can be reloaded into pcretest by specifing < and a file
532       When \O is used, it may be higher or lower than the size set         name instead of a pattern. The name of the file must not  contain  a  <
533       by  the  -O  option (or defaulted to 45); \O applies only to         character,  as  otherwise pcretest will interpret the line as a pattern
534       the call of pcre_exec() for the line in which it appears.         delimited by < characters.  For example:
535    
536       A backslash followed by anything else just escapes the  any-            re> </some/file
537       thing else. If the very last character is a backslash, it is           Compiled regex loaded from /some/file
538       ignored. This gives a way of passing an empty line as  data,           No study data
539       since a real empty line terminates the data input.  
540           When the pattern has been loaded, pcretest proceeds to read data  lines
541       If /P was present on the regex, causing  the  POSIX  wrapper         in the usual way.
542       API  to  be  used,  only  B,  and Z have any effect, causing  
543       REG_NOTBOL and REG_NOTEOL to be passed to regexec()  respec-         You  can copy a file written by pcretest to a different host and reload
544       tively.         it there, even if the new host has opposite endianness to  the  one  on
545       The use of \x{hh...} to represent UTF-8  characters  is  not         which  the pattern was compiled. For example, you can compile on an i86
546       dependent  on  the use of the /8 modifier on the pattern. It         machine and run on a SPARC machine.
547       is recognized always. There may be any number of hexadecimal  
548       digits  inside  the  braces.  The  result is from one to six         File names for saving and reloading can be absolute  or  relative,  but
549       bytes, encoded according to the UTF-8 rules.         note  that the shell facility of expanding a file name that starts with
550           a tilde (~) is not available.
551    
552  OUTPUT FROM PCRETEST         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       When a match succeeds, pcretest outputs the list of captured         only a single pattern can be written to a file. Furthermore,  there  is
555       substrings  that pcre_exec() returns, starting with number 0         no  facility  for  supplying  custom  character  tables  for use with a
556       for the string that matched the whole pattern.  Here  is  an         reloaded pattern. If the original  pattern  was  compiled  with  custom
557       example of an interactive pcretest run.         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         $ pcretest         a file that is not in the correct format, the result is undefined.
        PCRE version 4.00 08-Jan-2003  
   
          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 the sequences \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 addi-  
      tion 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.  
560    
561    
562  AUTHOR  AUTHOR
563    
564       Philip Hazel <ph10@cam.ac.uk>         Philip Hazel
565       University Computing Service,         University Computing Service,
566       Cambridge CB2 3QG, England.         Cambridge CB2 3QG, England.
567    
568  Last updated: 20 August 2003  Last updated: 29 June 2006
569  Copyright (c) 1997-2003 University of Cambridge.  Copyright (c) 1997-2006 University of Cambridge.

Legend:
Removed from v.71  
changed lines
  Added in v.91

  ViewVC Help
Powered by ViewVC 1.1.5