/[pcre]/code/trunk/doc/pcretest.txt
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revision 77 by nigel, Sat Feb 24 21:40:45 2007 UTC revision 87 by nigel, Sat Feb 24 21:41:21 2007 UTC
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1  PCRETEST(1)                                                        PCRETEST(1)  PCRETEST(1)                                                        PCRETEST(1)
2    
3    
   
4  NAME  NAME
5         pcretest - a program for testing Perl-compatible regular expressions.         pcretest - a program for testing Perl-compatible regular expressions.
6    
7    
8  SYNOPSIS  SYNOPSIS
9    
10         pcretest [-C] [-d] [-dfa] [-i] [-m] [-o osize] [-p] [-t] [source]         pcretest [-C] [-d] [-dfa] [-i] [-m] [-o osize] [-p] [-t] [source]
# Line 50  OPTIONS Line 50  OPTIONS
50                   per  API  is used to call PCRE. None of the other options has                   per  API  is used to call PCRE. None of the other options has
51                   any effect when -p is set.                   any effect when -p is set.
52    
53         -t        Run each compile, study, and match many times with  a  timer,         -q        Do not output the version number of pcretest at the start  of
54                   and  output resulting time per compile or match (in millisec-                   execution.
55                   onds). Do not set -m with -t, because you will then  get  the  
56                   size  output  a  zillion  times,  and the timing will be dis-         -t        Run  each  compile, study, and match many times with a timer,
57                     and output resulting time per compile or match (in  millisec-
58                     onds).  Do  not set -m with -t, because you will then get the
59                     size output a zillion times, and  the  timing  will  be  dis-
60                   torted.                   torted.
61    
62    
63  DESCRIPTION  DESCRIPTION
64    
65         If pcretest is given two filename arguments, it reads  from  the  first         If  pcretest  is  given two filename arguments, it reads from the first
66         and writes to the second. If it is given only one filename argument, it         and writes to the second. If it is given only one filename argument, it
67         reads from that file and writes to stdout.  Otherwise,  it  reads  from         reads  from  that  file  and writes to stdout. Otherwise, it reads from
68         stdin  and  writes to stdout, and prompts for each line of input, using         stdin and writes to stdout, and prompts for each line of  input,  using
69         "re>" to prompt for regular expressions, and "data>" to prompt for data         "re>" to prompt for regular expressions, and "data>" to prompt for data
70         lines.         lines.
71    
72         The program handles any number of sets of input on a single input file.         The program handles any number of sets of input on a single input file.
73         Each set starts with a regular expression, and continues with any  num-         Each  set starts with a regular expression, and continues with any num-
74         ber of data lines to be matched against the pattern.         ber of data lines to be matched against the pattern.
75    
76         Each  data line is matched separately and independently. If you want to         Each data line is matched separately and independently. If you want  to
77         do multiple-line matches, you have to use the \n escape sequence  in  a         do  multiple-line  matches, you have to use the \n escape sequence in a
78         single  line  of  input  to  encode the newline characters. The maximum         single line of input to encode  the  newline  characters.  The  maximum
79         length of data line is 30,000 characters.         length of data line is 30,000 characters.
80    
81         An empty line signals the end of the data lines, at which point  a  new         An  empty  line signals the end of the data lines, at which point a new
82         regular  expression is read. The regular expressions are given enclosed         regular expression is read. The regular expressions are given  enclosed
83         in any non-alphanumeric delimiters other than backslash, for example         in any non-alphanumeric delimiters other than backslash, for example
84    
85           /(a|bc)x+yz/           /(a|bc)x+yz/
86    
87         White space before the initial delimiter is ignored. A regular  expres-         White  space before the initial delimiter is ignored. A regular expres-
88         sion  may be continued over several input lines, in which case the new-         sion may be continued over several input lines, in which case the  new-
89         line characters are included within it. It is possible to  include  the         line  characters  are included within it. It is possible to include the
90         delimiter within the pattern by escaping it, for example         delimiter within the pattern by escaping it, for example
91    
92           /abc\/def/           /abc\/def/
93    
94         If  you  do  so, the escape and the delimiter form part of the pattern,         If you do so, the escape and the delimiter form part  of  the  pattern,
95         but since delimiters are always non-alphanumeric, this does not  affect         but  since delimiters are always non-alphanumeric, this does not affect
96         its  interpretation.   If the terminating delimiter is immediately fol-         its interpretation.  If the terminating delimiter is  immediately  fol-
97         lowed by a backslash, for example,         lowed by a backslash, for example,
98    
99           /abc/\           /abc/\
100    
101         then a backslash is added to the end of the pattern. This  is  done  to         then  a  backslash  is added to the end of the pattern. This is done to
102         provide  a  way of testing the error condition that arises if a pattern         provide a way of testing the error condition that arises if  a  pattern
103         finishes with a backslash, because         finishes with a backslash, because
104    
105           /abc\/           /abc\/
106    
107         is interpreted as the first line of a pattern that starts with  "abc/",         is  interpreted as the first line of a pattern that starts with "abc/",
108         causing pcretest to read the next line as a continuation of the regular         causing pcretest to read the next line as a continuation of the regular
109         expression.         expression.
110    
111    
112  PATTERN MODIFIERS  PATTERN MODIFIERS
113    
114         A pattern may be followed by any number of modifiers, which are  mostly         A  pattern may be followed by any number of modifiers, which are mostly
115         single  characters.  Following  Perl usage, these are referred to below         single characters. Following Perl usage, these are  referred  to  below
116         as, for example, "the /i modifier", even though the  delimiter  of  the         as,  for  example,  "the /i modifier", even though the delimiter of the
117         pattern  need  not always be a slash, and no slash is used when writing         pattern need not always be a slash, and no slash is used  when  writing
118         modifiers. Whitespace may appear between the  final  pattern  delimiter         modifiers.  Whitespace  may  appear between the final pattern delimiter
119         and the first modifier, and between the modifiers themselves.         and the first modifier, and between the modifiers themselves.
120    
121         The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,         The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
122         PCRE_DOTALL, or PCRE_EXTENDED  options,  respectively,  when  pcre_com-         PCRE_DOTALL,  or  PCRE_EXTENDED  options,  respectively, when pcre_com-
123         pile()  is  called. These four modifier letters have the same effect as         pile() is called. These four modifier letters have the same  effect  as
124         they do in Perl. For example:         they do in Perl. For example:
125    
126           /caseless/i           /caseless/i
# Line 133  PATTERN MODIFIERS Line 136  PATTERN MODIFIERS
136           /U    PCRE_UNGREEDY           /U    PCRE_UNGREEDY
137           /X    PCRE_EXTRA           /X    PCRE_EXTRA
138    
139         Searching  for  all  possible matches within each subject string can be         Searching for all possible matches within each subject  string  can  be
140         requested by the /g or /G modifier. After  finding  a  match,  PCRE  is         requested  by  the  /g  or  /G modifier. After finding a match, PCRE is
141         called again to search the remainder of the subject string. The differ-         called again to search the remainder of the subject string. The differ-
142         ence between /g and /G is that the former uses the startoffset argument         ence between /g and /G is that the former uses the startoffset argument
143         to  pcre_exec()  to  start  searching  at a new point within the entire         to pcre_exec() to start searching at a  new  point  within  the  entire
144         string (which is in effect what Perl does), whereas the  latter  passes         string  (which  is in effect what Perl does), whereas the latter passes
145         over  a  shortened  substring.  This makes a difference to the matching         over a shortened substring. This makes a  difference  to  the  matching
146         process if the pattern begins with a lookbehind assertion (including \b         process if the pattern begins with a lookbehind assertion (including \b
147         or \B).         or \B).
148    
149         If  any  call  to  pcre_exec()  in a /g or /G sequence matches an empty         If any call to pcre_exec() in a /g or  /G  sequence  matches  an  empty
150         string, the next call is done with the PCRE_NOTEMPTY and  PCRE_ANCHORED         string,  the next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED
151         flags  set in order to search for another, non-empty, match at the same         flags set in order to search for another, non-empty, match at the  same
152         point.  If this second match fails, the start  offset  is  advanced  by         point.   If  this  second  match fails, the start offset is advanced by
153         one,  and  the normal match is retried. This imitates the way Perl han-         one, and the normal match is retried. This imitates the way  Perl  han-
154         dles such cases when using the /g modifier or the split() function.         dles such cases when using the /g modifier or the split() function.
155    
156         There are yet more modifiers for controlling the way pcretest operates.         There are yet more modifiers for controlling the way pcretest operates.
157    
158         The  /+ modifier requests that as well as outputting the substring that         The /+ modifier requests that as well as outputting the substring  that
159         matched the entire pattern, pcretest  should  in  addition  output  the         matched  the  entire  pattern,  pcretest  should in addition output the
160         remainder  of  the  subject  string. This is useful for tests where the         remainder of the subject string. This is useful  for  tests  where  the
161         subject contains multiple copies of the same substring.         subject contains multiple copies of the same substring.
162    
163         The /L modifier must be followed directly by the name of a locale,  for         The  /L modifier must be followed directly by the name of a locale, for
164         example,         example,
165    
166           /pattern/Lfr_FR           /pattern/Lfr_FR
167    
168         For this reason, it must be the last modifier. The given locale is set,         For this reason, it must be the last modifier. The given locale is set,
169         pcre_maketables() is called to build a set of character tables for  the         pcre_maketables()  is called to build a set of character tables for the
170         locale,  and  this  is then passed to pcre_compile() when compiling the         locale, and this is then passed to pcre_compile()  when  compiling  the
171         regular expression. Without an /L  modifier,  NULL  is  passed  as  the         regular  expression.  Without  an  /L  modifier,  NULL is passed as the
172         tables  pointer; that is, /L applies only to the expression on which it         tables pointer; that is, /L applies only to the expression on which  it
173         appears.         appears.
174    
175         The /I modifier requests that pcretest  output  information  about  the         The  /I  modifier  requests  that pcretest output information about the
176         compiled  pattern (whether it is anchored, has a fixed first character,         compiled pattern (whether it is anchored, has a fixed first  character,
177         and so on). It does this by calling pcre_fullinfo() after  compiling  a         and  so  on). It does this by calling pcre_fullinfo() after compiling a
178         pattern.  If  the pattern is studied, the results of that are also out-         pattern. If the pattern is studied, the results of that are  also  out-
179         put.         put.
180    
181         The /D modifier is a PCRE debugging feature, which also assumes /I.  It         The /D modifier is a PCRE debugging feature, which also assumes /I.  It
182         causes  the  internal form of compiled regular expressions to be output         causes the internal form of compiled regular expressions to  be  output
183         after compilation. If the pattern was studied, the information returned         after compilation. If the pattern was studied, the information returned
184         is also output.         is also output.
185    
186         The /F modifier causes pcretest to flip the byte order of the fields in         The /F modifier causes pcretest to flip the byte order of the fields in
187         the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This         the  compiled  pattern  that  contain  2-byte  and 4-byte numbers. This
188         facility  is  for testing the feature in PCRE that allows it to execute         facility is for testing the feature in PCRE that allows it  to  execute
189         patterns that were compiled on a host with a different endianness. This         patterns that were compiled on a host with a different endianness. This
190         feature  is  not  available  when  the POSIX interface to PCRE is being         feature is not available when the POSIX  interface  to  PCRE  is  being
191         used, that is, when the /P pattern modifier is specified. See also  the         used,  that is, when the /P pattern modifier is specified. See also the
192         section about saving and reloading compiled patterns below.         section about saving and reloading compiled patterns below.
193    
194         The  /S  modifier causes pcre_study() to be called after the expression         The /S modifier causes pcre_study() to be called after  the  expression
195         has been compiled, and the results used when the expression is matched.         has been compiled, and the results used when the expression is matched.
196    
197         The  /M  modifier causes the size of memory block used to hold the com-         The /M modifier causes the size of memory block used to hold  the  com-
198         piled pattern to be output.         piled pattern to be output.
199    
200         The /P modifier causes pcretest to call PCRE via the POSIX wrapper  API         The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
201         rather  than  its  native  API.  When this is done, all other modifiers         rather than its native API. When this  is  done,  all  other  modifiers
202         except /i, /m, and /+ are ignored. REG_ICASE is set if /i  is  present,         except  /i,  /m, and /+ are ignored. REG_ICASE is set if /i is present,
203         and  REG_NEWLINE  is  set if /m is present. The wrapper functions force         and REG_NEWLINE is set if /m is present. The  wrapper  functions  force
204         PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is  set.         PCRE_DOLLAR_ENDONLY  always, and PCRE_DOTALL unless REG_NEWLINE is set.
205    
206         The  /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option         The /8 modifier causes pcretest to call PCRE with the PCRE_UTF8  option
207         set. This turns on support for UTF-8 character handling in  PCRE,  pro-         set.  This  turns on support for UTF-8 character handling in PCRE, pro-
208         vided  that  it  was  compiled with this support enabled. This modifier         vided that it was compiled with this  support  enabled.  This  modifier
209         also causes any non-printing characters in output strings to be printed         also causes any non-printing characters in output strings to be printed
210         using the \x{hh...} notation if they are valid UTF-8 sequences.         using the \x{hh...} notation if they are valid UTF-8 sequences.
211    
212         If  the  /?  modifier  is  used  with  /8,  it  causes pcretest to call         If the /? modifier  is  used  with  /8,  it  causes  pcretest  to  call
213         pcre_compile() with the  PCRE_NO_UTF8_CHECK  option,  to  suppress  the         pcre_compile()  with  the  PCRE_NO_UTF8_CHECK  option,  to suppress the
214         checking of the string for UTF-8 validity.         checking of the string for UTF-8 validity.
215    
216    
217  DATA LINES  DATA LINES
218    
219         Before  each  data  line is passed to pcre_exec(), leading and trailing         Before each data line is passed to pcre_exec(),  leading  and  trailing
220         whitespace is removed, and it is then scanned for \  escapes.  Some  of         whitespace  is  removed,  and it is then scanned for \ escapes. Some of
221         these  are  pretty esoteric features, intended for checking out some of         these are pretty esoteric features, intended for checking out  some  of
222         the more complicated features of PCRE. If you are just  testing  "ordi-         the  more  complicated features of PCRE. If you are just testing "ordi-
223         nary"  regular  expressions,  you probably don't need any of these. The         nary" regular expressions, you probably don't need any  of  these.  The
224         following escapes are recognized:         following escapes are recognized:
225    
226           \a         alarm (= BEL)           \a         alarm (= BEL)
# Line 257  DATA LINES Line 260  DATA LINES
260                        ated by next non-alphanumeric character)                        ated by next non-alphanumeric character)
261           \L         call pcre_get_substringlist() after a           \L         call pcre_get_substringlist() after a
262                        successful match                        successful match
263           \M         discover the minimum MATCH_LIMIT setting           \M         discover the minimum MATCH_LIMIT and
264                          MATCH_LIMIT_RECURSION settings
265           \N         pass the PCRE_NOTEMPTY option to pcre_exec()           \N         pass the PCRE_NOTEMPTY option to pcre_exec()
266           \Odd       set the size of the output vector passed to           \Odd       set the size of the output vector passed to
267                        pcre_exec() to dd (any number of digits)                        pcre_exec() to dd (any number of digits)
# Line 271  DATA LINES Line 275  DATA LINES
275           \>dd       start the match at offset dd (any number of digits);           \>dd       start the match at offset dd (any number of digits);
276                        this sets the startoffset argument for pcre_exec()                        this sets the startoffset argument for pcre_exec()
277    
278         A backslash followed by anything else just escapes the  anything  else.         A  backslash  followed by anything else just escapes the anything else.
279         If  the very last character is a backslash, it is ignored. This gives a         If the very last character is a backslash, it is ignored. This gives  a
280         way of passing an empty line as data, since a real  empty  line  termi-         way  of  passing  an empty line as data, since a real empty line termi-
281         nates the data input.         nates the data input.
282    
283         If  \M  is present, pcretest calls pcre_exec() several times, with dif-         If \M is present, pcretest calls pcre_exec() several times,  with  dif-
284         ferent values in the match_limit field of the  pcre_extra  data  struc-         ferent  values  in  the match_limit and match_limit_recursion fields of
285         ture,  until it finds the minimum number that is needed for pcre_exec()         the pcre_extra data structure, until it finds the minimum  numbers  for
286         to complete. This number is a measure of the amount  of  recursion  and         each parameter that allow pcre_exec() to complete. The match_limit num-
287         backtracking  that takes place, and checking it out can be instructive.         ber is a measure of the amount of backtracking that  takes  place,  and
288         For most simple matches, the number is quite small,  but  for  patterns         checking it out can be instructive. For most simple matches, the number
289         with  very large numbers of matching possibilities, it can become large         is quite small, but for patterns with very large  numbers  of  matching
290         very quickly with increasing length of subject string.         possibilities,  it can become large very quickly with increasing length
291           of subject string. The match_limit_recursion number is a measure of how
292           much  stack  (or,  if  PCRE is compiled with NO_RECURSE, how much heap)
293           memory is needed to complete the match attempt.
294    
295         When \O is used, the value specified may be higher or  lower  than  the         When \O is used, the value specified may be higher or  lower  than  the
296         size set by the -O command line option (or defaulted to 45); \O applies         size set by the -O command line option (or defaulted to 45); \O applies
297         only to the call of pcre_exec() for the line in which it appears.         only to the call of pcre_exec() for the line in which it appears.
298    
299         If the /P modifier was present on the pattern, causing the POSIX  wrap-         If the /P modifier was present on the pattern, causing the POSIX  wrap-
300         per  API to be used, only \B and \Z have any effect, causing REG_NOTBOL         per  API  to  be  used, the only option-setting sequences that have any
301         and REG_NOTEOL to be passed to regexec() respectively.         effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL,  respectively,
302           to be passed to regexec().
303         The use of \x{hh...} to represent UTF-8 characters is not dependent  on  
304         the  use  of  the  /8 modifier on the pattern. It is recognized always.         The  use of \x{hh...} to represent UTF-8 characters is not dependent on
305         There may be any number of hexadecimal digits inside  the  braces.  The         the use of the /8 modifier on the pattern.  It  is  recognized  always.
306         result  is from one to six bytes, encoded according to the UTF-8 rules.         There  may  be  any number of hexadecimal digits inside the braces. The
307           result is from one to six bytes, encoded according to the UTF-8  rules.
308    
309    
310  THE ALTERNATIVE MATCHING FUNCTION  THE ALTERNATIVE MATCHING FUNCTION
311    
312         By  default,  pcretest  uses  the  standard  PCRE  matching   function,         By   default,  pcretest  uses  the  standard  PCRE  matching  function,
313         pcre_exec() to match each data line. From release 6.0, PCRE supports an         pcre_exec() to match each data line. From release 6.0, PCRE supports an
314         alternative matching function, pcre_dfa_test(),  which  operates  in  a         alternative  matching  function,  pcre_dfa_test(),  which operates in a
315         different  way,  and has some restrictions. The differences between the         different way, and has some restrictions. The differences  between  the
316         two functions are described in the pcrematching documentation.         two functions are described in the pcrematching documentation.
317    
318         If a data line contains the \D escape sequence, or if the command  line         If  a data line contains the \D escape sequence, or if the command line
319         contains  the -dfa option, the alternative matching function is called.         contains the -dfa option, the alternative matching function is  called.
320         This function finds all possible matches at a given point. If, however,         This function finds all possible matches at a given point. If, however,
321         the  \F escape sequence is present in the data line, it stops after the         the \F escape sequence is present in the data line, it stops after  the
322         first match is found. This is always the shortest possible match.         first match is found. This is always the shortest possible match.
323    
324    
325  DEFAULT OUTPUT FROM PCRETEST  DEFAULT OUTPUT FROM PCRETEST
326    
327         This section describes the output when the  normal  matching  function,         This  section  describes  the output when the normal matching function,
328         pcre_exec(), is being used.         pcre_exec(), is being used.
329    
330         When a match succeeds, pcretest outputs the list of captured substrings         When a match succeeds, pcretest outputs the list of captured substrings
331         that pcre_exec() returns, starting with number 0 for  the  string  that         that  pcre_exec()  returns,  starting with number 0 for the string that
332         matched the whole pattern. Otherwise, it outputs "No match" or "Partial         matched the whole pattern. Otherwise, it outputs "No match" or "Partial
333         match" when pcre_exec() returns PCRE_ERROR_NOMATCH  or  PCRE_ERROR_PAR-         match"  when  pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
334         TIAL,  respectively, and otherwise the PCRE negative error number. Here         TIAL, respectively, and otherwise the PCRE negative error number.  Here
335         is an example of an interactive pcretest run.         is an example of an interactive pcretest run.
336    
337           $ pcretest           $ pcretest
# Line 336  DEFAULT OUTPUT FROM PCRETEST Line 344  DEFAULT OUTPUT FROM PCRETEST
344           data> xyz           data> xyz
345           No match           No match
346    
347         If the strings contain any non-printing characters, they are output  as         If  the strings contain any non-printing characters, they are output as
348         \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on         \0x escapes, or as \x{...} escapes if the /8 modifier  was  present  on
349         the pattern. If the pattern has the /+ modifier, the  output  for  sub-         the  pattern.  If  the pattern has the /+ modifier, the output for sub-
350         string  0 is followed by the the rest of the subject string, identified         string 0 is followed by the the rest of the subject string,  identified
351         by "0+" like this:         by "0+" like this:
352    
353             re> /cat/+             re> /cat/+
# Line 347  DEFAULT OUTPUT FROM PCRETEST Line 355  DEFAULT OUTPUT FROM PCRETEST
355            0: cat            0: cat
356            0+ aract            0+ aract
357    
358         If the pattern has the /g or /G modifier,  the  results  of  successive         If  the  pattern  has  the /g or /G modifier, the results of successive
359         matching attempts are output in sequence, like this:         matching attempts are output in sequence, like this:
360    
361             re> /\Bi(\w\w)/g             re> /\Bi(\w\w)/g
# Line 361  DEFAULT OUTPUT FROM PCRETEST Line 369  DEFAULT OUTPUT FROM PCRETEST
369    
370         "No match" is output only if the first match attempt fails.         "No match" is output only if the first match attempt fails.
371    
372         If  any  of the sequences \C, \G, or \L are present in a data line that         If any of the sequences \C, \G, or \L are present in a data  line  that
373         is successfully matched, the substrings extracted  by  the  convenience         is  successfully  matched,  the substrings extracted by the convenience
374         functions are output with C, G, or L after the string number instead of         functions are output with C, G, or L after the string number instead of
375         a colon. This is in addition to the normal full list. The string length         a colon. This is in addition to the normal full list. The string length
376         (that  is,  the return from the extraction function) is given in paren-         (that is, the return from the extraction function) is given  in  paren-
377         theses after each string for \C and \G.         theses after each string for \C and \G.
378    
379         Note that while patterns can be continued over several lines  (a  plain         Note  that  while patterns can be continued over several lines (a plain
380         ">" prompt is used for continuations), data lines may not. However new-         ">" prompt is used for continuations), data lines may not. However new-
381         lines can be included in data by means of the \n escape.         lines can be included in data by means of the \n escape.
382    
383    
384  OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION  OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
385    
386         When the alternative matching function, pcre_dfa_exec(),  is  used  (by         When  the  alternative  matching function, pcre_dfa_exec(), is used (by
387         means  of  the \D escape sequence or the -dfa command line option), the         means of the \D escape sequence or the -dfa command line  option),  the
388         output consists of a list of all the matches that start  at  the  first         output  consists  of  a list of all the matches that start at the first
389         point in the subject where there is at least one match. For example:         point in the subject where there is at least one match. For example:
390    
391             re> /(tang|tangerine|tan)/             re> /(tang|tangerine|tan)/
# Line 386  OUTPUT FROM THE ALTERNATIVE MATCHING FUN Line 394  OUTPUT FROM THE ALTERNATIVE MATCHING FUN
394            1: tang            1: tang
395            2: tan            2: tan
396    
397         (Using  the  normal  matching function on this data finds only "tang".)         (Using the normal matching function on this data  finds  only  "tang".)
398         The longest matching string is always given first (and numbered  zero).         The  longest matching string is always given first (and numbered zero).
399    
400         If  /gP  is  present  on  the  pattern,  the search for further matches         If /gP is present on  the  pattern,  the  search  for  further  matches
401         resumes at the end of the longest match. For example:         resumes at the end of the longest match. For example:
402    
403             re> /(tang|tangerine|tan)/g             re> /(tang|tangerine|tan)/g
# Line 401  OUTPUT FROM THE ALTERNATIVE MATCHING FUN Line 409  OUTPUT FROM THE ALTERNATIVE MATCHING FUN
409            1: tan            1: tan
410            0: tan            0: tan
411    
412         Since the matching function does not  support  substring  capture,  the         Since  the  matching  function  does not support substring capture, the
413         escape  sequences  that  are concerned with captured substrings are not         escape sequences that are concerned with captured  substrings  are  not
414         relevant.         relevant.
415    
416    
417  RESTARTING AFTER A PARTIAL MATCH  RESTARTING AFTER A PARTIAL MATCH
418    
419         When the alternative matching function has given the PCRE_ERROR_PARTIAL         When the alternative matching function has given the PCRE_ERROR_PARTIAL
420         return,  indicating that the subject partially matched the pattern, you         return, indicating that the subject partially matched the pattern,  you
421         can restart the match with additional subject data by means of  the  \R         can  restart  the match with additional subject data by means of the \R
422         escape sequence. For example:         escape sequence. For example:
423    
424             re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/             re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/
# Line 419  RESTARTING AFTER A PARTIAL MATCH Line 427  RESTARTING AFTER A PARTIAL MATCH
427           data> n05\R\D           data> n05\R\D
428            0: n05            0: n05
429    
430         For  further  information  about  partial matching, see the pcrepartial         For further information about partial  matching,  see  the  pcrepartial
431         documentation.         documentation.
432    
433    
434  CALLOUTS  CALLOUTS
435    
436         If the pattern contains any callout requests, pcretest's callout  func-         If  the pattern contains any callout requests, pcretest's callout func-
437         tion  is  called  during  matching. This works with both matching func-         tion is called during matching. This works  with  both  matching  func-
438         tions. By default, the called function displays the callout number, the         tions. By default, the called function displays the callout number, the
439         start  and  current  positions in the text at the callout time, and the         start and current positions in the text at the callout  time,  and  the
440         next pattern item to be tested. For example, the output         next pattern item to be tested. For example, the output
441    
442           --->pqrabcdef           --->pqrabcdef
443             0    ^  ^     \d             0    ^  ^     \d
444    
445         indicates that callout number 0 occurred for a match  attempt  starting         indicates  that  callout number 0 occurred for a match attempt starting
446         at  the fourth character of the subject string, when the pointer was at         at the fourth character of the subject string, when the pointer was  at
447         the seventh character of the data, and when the next pattern  item  was         the  seventh  character of the data, and when the next pattern item was
448         \d.  Just  one  circumflex is output if the start and current positions         \d. Just one circumflex is output if the start  and  current  positions
449         are the same.         are the same.
450    
451         Callouts numbered 255 are assumed to be automatic callouts, inserted as         Callouts numbered 255 are assumed to be automatic callouts, inserted as
452         a  result  of the /C pattern modifier. In this case, instead of showing         a result of the /C pattern modifier. In this case, instead  of  showing
453         the callout number, the offset in the pattern, preceded by a  plus,  is         the  callout  number, the offset in the pattern, preceded by a plus, is
454         output. For example:         output. For example:
455    
456             re> /\d?[A-E]\*/C             re> /\d?[A-E]\*/C
# Line 454  CALLOUTS Line 462  CALLOUTS
462           +10 ^ ^           +10 ^ ^
463            0: E*            0: E*
464    
465         The  callout  function  in pcretest returns zero (carry on matching) by         The callout function in pcretest returns zero (carry  on  matching)  by
466         default, but you can use a \C item in a data line (as described  above)         default,  but you can use a \C item in a data line (as described above)
467         to change this.         to change this.
468    
469         Inserting  callouts can be helpful when using pcretest to check compli-         Inserting callouts can be helpful when using pcretest to check  compli-
470         cated regular expressions. For further information about callouts,  see         cated  regular expressions. For further information about callouts, see
471         the pcrecallout documentation.         the pcrecallout documentation.
472    
473    
474  SAVING AND RELOADING COMPILED PATTERNS  SAVING AND RELOADING COMPILED PATTERNS
475    
476         The  facilities  described  in  this section are not available when the         The facilities described in this section are  not  available  when  the
477         POSIX inteface to PCRE is being used, that is, when the /P pattern mod-         POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
478         ifier is specified.         ifier is specified.
479    
480         When the POSIX interface is not in use, you can cause pcretest to write         When the POSIX interface is not in use, you can cause pcretest to write
481         a compiled pattern to a file, by following the modifiers with >  and  a         a  compiled  pattern to a file, by following the modifiers with > and a
482         file name.  For example:         file name.  For example:
483    
484           /pattern/im >/some/file           /pattern/im >/some/file
485    
486         See  the pcreprecompile documentation for a discussion about saving and         See the pcreprecompile documentation for a discussion about saving  and
487         re-using compiled patterns.         re-using compiled patterns.
488    
489         The data that is written is binary.  The  first  eight  bytes  are  the         The  data  that  is  written  is  binary. The first eight bytes are the
490         length  of  the  compiled  pattern  data  followed by the length of the         length of the compiled pattern data  followed  by  the  length  of  the
491         optional study data, each written as four  bytes  in  big-endian  order         optional  study  data,  each  written as four bytes in big-endian order
492         (most  significant  byte  first). If there is no study data (either the         (most significant byte first). If there is no study  data  (either  the
493         pattern was not studied, or studying did not return any data), the sec-         pattern was not studied, or studying did not return any data), the sec-
494         ond  length  is  zero. The lengths are followed by an exact copy of the         ond length is zero. The lengths are followed by an exact  copy  of  the
495         compiled pattern. If there is additional study data, this follows imme-         compiled pattern. If there is additional study data, this follows imme-
496         diately  after  the  compiled pattern. After writing the file, pcretest         diately after the compiled pattern. After writing  the  file,  pcretest
497         expects to read a new pattern.         expects to read a new pattern.
498    
499         A saved pattern can be reloaded into pcretest by specifing < and a file         A saved pattern can be reloaded into pcretest by specifing < and a file
500         name  instead  of  a pattern. The name of the file must not contain a <         name instead of a pattern. The name of the file must not  contain  a  <
501         character, as otherwise pcretest will interpret the line as  a  pattern         character,  as  otherwise pcretest will interpret the line as a pattern
502         delimited by < characters.  For example:         delimited by < characters.  For example:
503    
504            re> </some/file            re> </some/file
505           Compiled regex loaded from /some/file           Compiled regex loaded from /some/file
506           No study data           No study data
507    
508         When  the pattern has been loaded, pcretest proceeds to read data lines         When the pattern has been loaded, pcretest proceeds to read data  lines
509         in the usual way.         in the usual way.
510    
511         You can copy a file written by pcretest to a different host and  reload         You  can copy a file written by pcretest to a different host and reload
512         it  there,  even  if the new host has opposite endianness to the one on         it there, even if the new host has opposite endianness to  the  one  on
513         which the pattern was compiled. For example, you can compile on an  i86         which  the pattern was compiled. For example, you can compile on an i86
514         machine and run on a SPARC machine.         machine and run on a SPARC machine.
515    
516         File  names  for  saving and reloading can be absolute or relative, but         File names for saving and reloading can be absolute  or  relative,  but
517         note that the shell facility of expanding a file name that starts  with         note  that the shell facility of expanding a file name that starts with
518         a tilde (~) is not available.         a tilde (~) is not available.
519    
520         The  ability to save and reload files in pcretest is intended for test-         The ability to save and reload files in pcretest is intended for  test-
521         ing and experimentation. It is not intended for production use  because         ing  and experimentation. It is not intended for production use because
522         only  a  single pattern can be written to a file. Furthermore, there is         only a single pattern can be written to a file. Furthermore,  there  is
523         no facility for supplying  custom  character  tables  for  use  with  a         no  facility  for  supplying  custom  character  tables  for use with a
524         reloaded  pattern.  If  the  original  pattern was compiled with custom         reloaded pattern. If the original  pattern  was  compiled  with  custom
525         tables, an attempt to match a subject string using a  reloaded  pattern         tables,  an  attempt to match a subject string using a reloaded pattern
526         is  likely to cause pcretest to crash.  Finally, if you attempt to load         is likely to cause pcretest to crash.  Finally, if you attempt to  load
527         a file that is not in the correct format, the result is undefined.         a file that is not in the correct format, the result is undefined.
528    
529    
# Line 525  AUTHOR Line 533  AUTHOR
533         University Computing Service,         University Computing Service,
534         Cambridge CB2 3QG, England.         Cambridge CB2 3QG, England.
535    
536  Last updated: 28 February 2005  Last updated: 18 January 2006
537  Copyright (c) 1997-2005 University of Cambridge.  Copyright (c) 1997-2006 University of Cambridge.

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