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1  NAME  PCRETEST(1)                                                        PCRETEST(1)
2       pcretest - a program  for  testing  Perl-compatible  regular  
3       expressions.  
4    
5    NAME
6           pcretest - a program for testing Perl-compatible regular expressions.
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 [-C] [-d] [-dfa] [-i] [-m] [-o osize] [-p] [-t] [source]
11       expression  library  itself,  but  it  can  also be used for              [destination]
      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.  
12    
13           pcretest  was written as a test program for the PCRE regular expression
14           library itself, but it can also be used for experimenting with  regular
15           expressions.  This document describes the features of the test program;
16           for details of the regular expressions themselves, see the  pcrepattern
17           documentation. For details of the PCRE library function calls and their
18           options, see the pcreapi documentation.
19    
 OPTIONS  
20    
21    OPTIONS
22    
23       -C        Output the version number of the PCRE library, and         -C        Output the version number of the PCRE library, and all avail-
24                 all   available  information  about  the  optional                   able   information  about  the  optional  features  that  are
25                 features that are included, and then exit.                   included, and then exit.
26    
27       -d        Behave as if each regex had the /D  modifier  (see         -d        Behave as if each regex has  the  /D  (debug)  modifier;  the
28                 below); the internal form is output after compila-                   internal form is output after compilation.
29                 tion.  
30           -dfa      Behave  as if each data line contains the \D escape sequence;
31       -i        Behave as if  each  regex  had  the  /I  modifier;                   this    causes    the    alternative    matching    function,
32                 information  about  the  compiled pattern is given                   pcre_dfa_exec(),   to   be   used  instead  of  the  standard
33                 after compilation.                   pcre_exec() function (more detail is given below).
34    
35       -m        Output the size of each compiled pattern after  it         -i        Behave as if each regex  has  the  /I  modifier;  information
36                 has been compiled. This is equivalent to adding /M                   about the compiled pattern is given after compilation.
37                 to each regular expression. For compatibility with  
38                 earlier  versions of pcretest, -s is a synonym for         -m        Output  the  size  of each compiled pattern after it has been
39                 -m.                   compiled. This is equivalent to adding  /M  to  each  regular
40                     expression.   For  compatibility  with  earlier  versions  of
41       -o osize  Set the number of elements in  the  output  vector                   pcretest, -s is a synonym for -m.
42                 that  is  used  when calling PCRE to be osize. The  
43                 default value is 45, which is enough for  14  cap-         -o osize  Set the number of elements in the output vector that is  used
44                 turing  subexpressions.  The  vector  size  can be                   when  calling  pcre_exec()  to be osize. The default value is
45                 changed for individual matching calls by including                   45, which is enough for 14 capturing subexpressions. The vec-
46                 \O in the data line (see below).                   tor  size  can  be  changed  for individual matching calls by
47                     including \O in the data line (see below).
48       -p        Behave as if each regex has /P modifier; the POSIX  
49                 wrapper  API  is  used  to  call PCRE. None of the         -p        Behave as if each regex has the /P modifier; the POSIX  wrap-
50                 other options has any effect when -p is set.                   per  API  is used to call PCRE. None of the other options has
51                     any effect when -p is set.
52       -t        Run each compile, study, and match many times with  
53                 a  timer, and output resulting time per compile or         -t        Run each compile, study, and match many times with  a  timer,
54                 match (in milliseconds). Do not set  -t  with  -m,                   and  output resulting time per compile or match (in millisec-
55                 because  you  will  then get the size output 20000                   onds). Do not set -m with -t, because you will then  get  the
56                 times and the timing will be distorted.                   size  output  a  zillion  times,  and the timing will be dis-
57                     torted.
58    
59    
60  DESCRIPTION  DESCRIPTION
61    
62       If pcretest is given two filename arguments, it  reads  from         If pcretest is given two filename arguments, it reads  from  the  first
63       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
64       filename argument, it reads from that  file  and  writes  to         reads from that file and writes to stdout.  Otherwise,  it  reads  from
65       stdout. Otherwise, it reads from stdin and writes to stdout,         stdin  and  writes to stdout, and prompts for each line of input, using
66       and prompts for each line of input, using  "re>"  to  prompt         "re>" to prompt for regular expressions, and "data>" to prompt for data
67       for  regular  expressions,  and  "data>"  to prompt for data         lines.
68       lines.  
69           The program handles any number of sets of input on a single input file.
70       The program handles any number of sets of input on a  single         Each set starts with a regular expression, and continues with any  num-
71       input  file.  Each set starts with a regular expression, and         ber of data lines to be matched against the pattern.
72       continues with any  number  of  data  lines  to  be  matched  
73       against the pattern.         Each  data line is matched separately and independently. If you want to
74           do multiple-line matches, you have to use the \n escape sequence  in  a
75       Each line is matched separately and  independently.  If  you         single  line  of  input  to  encode the newline characters. The maximum
76       want  to  do  multiple-line  matches, you have to use the \n         length of data line is 30,000 characters.
77       escape sequence in a single line of input to encode the new-  
78       line  characters.  The maximum length of data line is 30,000         An empty line signals the end of the data lines, at which point  a  new
79       characters.         regular  expression is read. The regular expressions are given enclosed
80           in any non-alphanumeric delimiters other than backslash, for example
81       An empty line signals the end of the data  lines,  at  which  
82       point  a new regular expression is read. The regular expres-           /(a|bc)x+yz/
83       sions are given enclosed in  any  non-alphameric  delimiters  
84       other than backslash, for example         White space before the initial delimiter is ignored. A regular  expres-
85           sion  may be continued over several input lines, in which case the new-
86         /(a|bc)x+yz/         line characters are included within it. It is possible to  include  the
87           delimiter within the pattern by escaping it, for example
88       White space before the initial delimiter is ignored. A regu-  
89       lar expression may be continued over several input lines, in           /abc\/def/
90       which case the newline characters are included within it. It  
91       is  possible  to include the delimiter within the pattern by         If  you  do  so, the escape and the delimiter form part of the pattern,
92       escaping it, for example         but since delimiters are always non-alphanumeric, this does not  affect
93           its  interpretation.   If the terminating delimiter is immediately fol-
94         /abc\/def/         lowed by a backslash, for example,
95    
96       If you do so, the escape and the delimiter form part of  the           /abc/\
97       pattern,  but  since  delimiters  are always non-alphameric,  
98       this does not affect its interpretation.  If the terminating         then a backslash is added to the end of the pattern. This  is  done  to
99       delimiter  is immediately followed by a backslash, for exam-         provide  a  way of testing the error condition that arises if a pattern
100       ple,         finishes with a backslash, because
101    
102         /abc/\           /abc\/
103    
104       then a backslash is added to the end of the pattern. This is         is interpreted as the first line of a pattern that starts with  "abc/",
105       done  to  provide  a way of testing the error condition that         causing pcretest to read the next line as a continuation of the regular
106       arises if a pattern finishes with a backslash, because         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.  
107    
108    
109  PATTERN MODIFIERS  PATTERN MODIFIERS
110    
111       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
112       PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED         single  characters.  Following  Perl usage, these are referred to below
113       options, respectively. For example:         as, for example, "the /i modifier", even though the  delimiter  of  the
114           pattern  need  not always be a slash, and no slash is used when writing
115         /caseless/i         modifiers. Whitespace may appear between the  final  pattern  delimiter
116           and the first modifier, and between the modifiers themselves.
117       These modifier letters have the same effect as  they  do  in  
118       Perl.  There  are  others which set PCRE options that do not         The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
119       correspond  to  anything  in  Perl:   /A,  /E,  and  /X  set         PCRE_DOTALL, or PCRE_EXTENDED  options,  respectively,  when  pcre_com-
120       PCRE_ANCHORED,  PCRE_DOLLAR_ENDONLY,  and PCRE_EXTRA respec-         pile()  is  called. These four modifier letters have the same effect as
121       tively.         they do in Perl. For example:
122    
123       Searching for  all  possible  matches  within  each  subject           /caseless/i
124       string  can  be  requested  by  the /g or /G modifier. After  
125       finding  a  match,  PCRE  is  called  again  to  search  the         The following table shows additional modifiers for setting PCRE options
126       remainder  of  the subject string. The difference between /g         that do not correspond to anything in Perl:
127       and /G is that the former uses the startoffset  argument  to  
128       pcre_exec()  to  start  searching  at a new point within the           /A    PCRE_ANCHORED
129       entire string (which is in effect what Perl  does),  whereas           /C    PCRE_AUTO_CALLOUT
130       the  latter  passes over a shortened substring. This makes a           /E    PCRE_DOLLAR_ENDONLY
131       difference to the matching process  if  the  pattern  begins           /f    PCRE_FIRSTLINE
132       with a lookbehind assertion (including \b or \B).           /N    PCRE_NO_AUTO_CAPTURE
133             /U    PCRE_UNGREEDY
134       If any call to pcre_exec() in a /g or /G sequence matches an           /X    PCRE_EXTRA
135       empty  string,  the next call is done with the PCRE_NOTEMPTY  
136       and PCRE_ANCHORED flags set in order to search for  another,         Searching  for  all  possible matches within each subject string can be
137       non-empty,  match  at  the same point.  If this second match         requested by the /g or /G modifier. After  finding  a  match,  PCRE  is
138       fails, the start offset is advanced by one, and  the  normal         called again to search the remainder of the subject string. The differ-
139       match  is  retried.  This imitates the way Perl handles such         ence between /g and /G is that the former uses the startoffset argument
140       cases when using the /g modifier or the split() function.         to  pcre_exec()  to  start  searching  at a new point within the entire
141           string (which is in effect what Perl does), whereas the  latter  passes
142       There are a number of other modifiers  for  controlling  the         over  a  shortened  substring.  This makes a difference to the matching
143       way pcretest operates.         process if the pattern begins with a lookbehind assertion (including \b
144           or \B).
145       The /+ modifier requests that as well as outputting the sub-  
146       string  that  matched the entire pattern, pcretest should in         If  any  call  to  pcre_exec()  in a /g or /G sequence matches an empty
147       addition output the remainder of the subject string. This is         string, the next call is done with the PCRE_NOTEMPTY and  PCRE_ANCHORED
148       useful  for tests where the subject contains multiple copies         flags  set in order to search for another, non-empty, match at the same
149       of the same substring.         point.  If this second match fails, the start  offset  is  advanced  by
150           one,  and  the normal match is retried. This imitates the way Perl han-
151       The /L modifier must be followed directly by the name  of  a         dles such cases when using the /g modifier or the split() function.
152       locale, for example,  
153           There are yet more modifiers for controlling the way pcretest operates.
154         /pattern/Lfr  
155           The  /+ modifier requests that as well as outputting the substring that
156       For this reason, it must be the last  modifier  letter.  The         matched the entire pattern, pcretest  should  in  addition  output  the
157       given  locale is set, pcre_maketables() is called to build a         remainder  of  the  subject  string. This is useful for tests where the
158       set of character tables for the locale,  and  this  is  then         subject contains multiple copies of the same substring.
159       passed  to pcre_compile() when compiling the regular expres-  
160       sion. Without an /L modifier, NULL is passed as  the  tables         The /L modifier must be followed directly by the name of a locale,  for
161       pointer; that is, /L applies only to the expression on which         example,
162       it appears.  
163             /pattern/Lfr_FR
164       The /I modifier requests that  pcretest  output  information  
165       about the compiled expression (whether it is anchored, has a         For this reason, it must be the last modifier. The given locale is set,
166       fixed first character, and so on). It does this  by  calling         pcre_maketables() is called to build a set of character tables for  the
167       pcre_fullinfo()  after  compiling an expression, and output-         locale,  and  this  is then passed to pcre_compile() when compiling the
168       ting the information it gets back. If the  pattern  is  stu-         regular expression. Without an /L  modifier,  NULL  is  passed  as  the
169       died, the results of that are also output.         tables  pointer; that is, /L applies only to the expression on which it
170           appears.
171       The /D modifier is a  PCRE  debugging  feature,  which  also  
172       assumes /I.  It causes the internal form of compiled regular         The /I modifier requests that pcretest  output  information  about  the
173       expressions to be output after compilation. If  the  pattern         compiled  pattern (whether it is anchored, has a fixed first character,
174       was studied, the information returned is also output.         and so on). It does this by calling pcre_fullinfo() after  compiling  a
175           pattern.  If  the pattern is studied, the results of that are also out-
176       The /S modifier causes pcre_study() to be called  after  the         put.
177       expression  has been compiled, and the results used when the  
178       expression is matched.         The /D modifier is a PCRE debugging feature, which also assumes /I.  It
179           causes  the  internal form of compiled regular expressions to be output
180       The /M modifier causes the size of memory block used to hold         after compilation. If the pattern was studied, the information returned
181       the compiled pattern to be output.         is also output.
182    
183       The /P modifier causes pcretest to call PCRE via  the  POSIX         The /F modifier causes pcretest to flip the byte order of the fields in
184       wrapper  API  rather than its native API. When this is done,         the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This
185       all other modifiers except  /i,  /m,  and  /+  are  ignored.         facility  is  for testing the feature in PCRE that allows it to execute
186       REG_ICASE is set if /i is present, and REG_NEWLINE is set if         patterns that were compiled on a host with a different endianness. This
187       /m    is    present.    The    wrapper    functions    force         feature  is  not  available  when  the POSIX interface to PCRE is being
188       PCRE_DOLLAR_ENDONLY    always,    and   PCRE_DOTALL   unless         used, that is, when the /P pattern modifier is specified. See also  the
189       REG_NEWLINE is set.         section about saving and reloading compiled patterns below.
190    
191       The /8 modifier  causes  pcretest  to  call  PCRE  with  the         The  /S  modifier causes pcre_study() to be called after the expression
192       PCRE_UTF8  option set. This turns on support for UTF-8 char-         has been compiled, and the results used when the expression is matched.
193       acter handling in PCRE, provided that it was  compiled  with  
194       this  support  enabled.  This  modifier also causes any non-         The  /M  modifier causes the size of memory block used to hold the com-
195       printing characters in output strings to  be  printed  using         piled pattern to be output.
196       the \x{hh...} notation if they are valid UTF-8 sequences.  
197           The /P modifier causes pcretest to call PCRE via the POSIX wrapper  API
198           rather  than  its  native  API.  When this is done, all other modifiers
199           except /i, /m, and /+ are ignored. REG_ICASE is set if /i  is  present,
200           and  REG_NEWLINE  is  set if /m is present. The wrapper functions force
201           PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is  set.
202    
203           The  /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
204           set. This turns on support for UTF-8 character handling in  PCRE,  pro-
205           vided  that  it  was  compiled with this support enabled. This modifier
206           also causes any non-printing characters in output strings to be printed
207           using the \x{hh...} notation if they are valid UTF-8 sequences.
208    
209           If  the  /?  modifier  is  used  with  /8,  it  causes pcretest to call
210           pcre_compile() with the  PCRE_NO_UTF8_CHECK  option,  to  suppress  the
211           checking of the string for UTF-8 validity.
212    
213    
214  CALLOUTS  DATA LINES
215    
216       If the pattern contains  any  callout  requests,  pcretest's         Before  each  data  line is passed to pcre_exec(), leading and trailing
217       callout function will be called. By default, it displays the         whitespace is removed, and it is then scanned for \  escapes.  Some  of
218       callout number, and the start and current positions  in  the         these  are  pretty esoteric features, intended for checking out some of
219       text at the callout time. For example, the output         the more complicated features of PCRE. If you are just  testing  "ordi-
220           nary"  regular  expressions,  you probably don't need any of these. The
221         --->pqrabcdef         following escapes are recognized:
222           0    ^  ^  
223             \a         alarm (= BEL)
224       indicates that callout number 0 occurred for a match attempt           \b         backspace
225       starting at the fourth character of the subject string, when           \e         escape
226       the pointer was at the seventh character. The callout  func-           \f         formfeed
227       tion returns zero (carry on matching) by default.           \n         newline
228             \r         carriage return
229       Inserting callouts may be helpful  when  using  pcretest  to           \t         tab
230       check  complicated regular expressions. For further informa-           \v         vertical tab
231       tion about callouts, see the pcrecallout documentation.           \nnn       octal character (up to 3 octal digits)
232             \xhh       hexadecimal character (up to 2 hex digits)
233       For testing the PCRE library, additional control of  callout           \x{hh...}  hexadecimal character, any number of digits
234       behaviour  is available via escape sequences in the data, as                        in UTF-8 mode
235       described in the following section.  In  particular,  it  is           \A         pass the PCRE_ANCHORED option to pcre_exec()
236       possible to pass in a number as callout data (the default is           \B         pass the PCRE_NOTBOL option to pcre_exec()
237       zero). If the callout function receives a  non-zero  number,           \Cdd       call pcre_copy_substring() for substring dd
238       it returns that value instead of zero.                        after a successful match (number less than 32)
239             \Cname     call pcre_copy_named_substring() for substring
240                          "name" after a successful match (name termin-
241                          ated by next non alphanumeric character)
242             \C+        show the current captured substrings at callout
243                          time
244             \C-        do not supply a callout function
245             \C!n       return 1 instead of 0 when callout number n is
246                          reached
247             \C!n!m     return 1 instead of 0 when callout number n is
248                          reached for the nth time
249             \C*n       pass the number n (may be negative) as callout
250                          data; this is used as the callout return value
251             \D         use the pcre_dfa_exec() match function
252             \F         only shortest match for pcre_dfa_exec()
253             \Gdd       call pcre_get_substring() for substring dd
254                          after a successful match (number less than 32)
255             \Gname     call pcre_get_named_substring() for substring
256                          "name" after a successful match (name termin-
257                          ated by next non-alphanumeric character)
258             \L         call pcre_get_substringlist() after a
259                          successful match
260             \M         discover the minimum MATCH_LIMIT setting
261             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
262             \Odd       set the size of the output vector passed to
263                          pcre_exec() to dd (any number of digits)
264             \P         pass the PCRE_PARTIAL option to pcre_exec()
265                          or pcre_dfa_exec()
266             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
267             \S         output details of memory get/free calls during matching
268             \Z         pass the PCRE_NOTEOL option to pcre_exec()
269             \?         pass the PCRE_NO_UTF8_CHECK option to
270                          pcre_exec()
271             \>dd       start the match at offset dd (any number of digits);
272                          this sets the startoffset argument for pcre_exec()
273    
274           A backslash followed by anything else just escapes the  anything  else.
275           If  the very last character is a backslash, it is ignored. This gives a
276           way of passing an empty line as data, since a real  empty  line  termi-
277           nates the data input.
278    
279           If  \M  is present, pcretest calls pcre_exec() several times, with dif-
280           ferent values in the match_limit field of the  pcre_extra  data  struc-
281           ture,  until it finds the minimum number that is needed for pcre_exec()
282           to complete. This number is a measure of the amount  of  recursion  and
283           backtracking  that takes place, and checking it out can be instructive.
284           For most simple matches, the number is quite small,  but  for  patterns
285           with  very large numbers of matching possibilities, it can become large
286           very quickly with increasing length of subject string.
287    
288           When \O is used, the value specified may be higher or  lower  than  the
289           size set by the -O command line option (or defaulted to 45); \O applies
290           only to the call of pcre_exec() for the line in which it appears.
291    
292           If the /P modifier was present on the pattern, causing the POSIX  wrap-
293           per  API to be used, only \B and \Z have any effect, causing REG_NOTBOL
294           and REG_NOTEOL to be passed to regexec() respectively.
295    
296           The use of \x{hh...} to represent UTF-8 characters is not dependent  on
297           the  use  of  the  /8 modifier on the pattern. It is recognized always.
298           There may be any number of hexadecimal digits inside  the  braces.  The
299           result  is from one to six bytes, encoded according to the UTF-8 rules.
300    
301    
302    THE ALTERNATIVE MATCHING FUNCTION
303    
304           By  default,  pcretest  uses  the  standard  PCRE  matching   function,
305           pcre_exec() to match each data line. From release 6.0, PCRE supports an
306           alternative matching function, pcre_dfa_test(),  which  operates  in  a
307           different  way,  and has some restrictions. The differences between the
308           two functions are described in the pcrematching documentation.
309    
310           If a data line contains the \D escape sequence, or if the command  line
311           contains  the -dfa option, the alternative matching function is called.
312           This function finds all possible matches at a given point. If, however,
313           the  \F escape sequence is present in the data line, it stops after the
314           first match is found. This is always the shortest possible match.
315    
316    
317    DEFAULT OUTPUT FROM PCRETEST
318    
319           This section describes the output when the  normal  matching  function,
320           pcre_exec(), is being used.
321    
322           When a match succeeds, pcretest outputs the list of captured substrings
323           that pcre_exec() returns, starting with number 0 for  the  string  that
324           matched the whole pattern. Otherwise, it outputs "No match" or "Partial
325           match" when pcre_exec() returns PCRE_ERROR_NOMATCH  or  PCRE_ERROR_PAR-
326           TIAL,  respectively, and otherwise the PCRE negative error number. Here
327           is an example of an interactive pcretest run.
328    
329             $ pcretest
330             PCRE version 5.00 07-Sep-2004
331    
332               re> /^abc(\d+)/
333             data> abc123
334              0: abc123
335              1: 123
336             data> xyz
337             No match
338    
339           If the strings contain any non-printing characters, they are output  as
340           \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
341           the pattern. If the pattern has the /+ modifier, the  output  for  sub-
342           string  0 is followed by the the rest of the subject string, identified
343           by "0+" like this:
344    
345               re> /cat/+
346             data> cataract
347              0: cat
348              0+ aract
349    
350           If the pattern has the /g or /G modifier,  the  results  of  successive
351           matching attempts are output in sequence, like this:
352    
353               re> /\Bi(\w\w)/g
354             data> Mississippi
355              0: iss
356              1: ss
357              0: iss
358              1: ss
359              0: ipp
360              1: pp
361    
362           "No match" is output only if the first match attempt fails.
363    
364           If  any  of the sequences \C, \G, or \L are present in a data line that
365           is successfully matched, the substrings extracted  by  the  convenience
366           functions are output with C, G, or L after the string number instead of
367           a colon. This is in addition to the normal full list. The string length
368           (that  is,  the return from the extraction function) is given in paren-
369           theses after each string for \C and \G.
370    
371           Note that while patterns can be continued over several lines  (a  plain
372           ">" prompt is used for continuations), data lines may not. However new-
373           lines can be included in data by means of the \n escape.
374    
375    
376    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
377    
378           When the alternative matching function, pcre_dfa_exec(),  is  used  (by
379           means  of  the \D escape sequence or the -dfa command line option), the
380           output consists of a list of all the matches that start  at  the  first
381           point in the subject where there is at least one match. For example:
382    
383               re> /(tang|tangerine|tan)/
384             data> yellow tangerine\D
385              0: tangerine
386              1: tang
387              2: tan
388    
389           (Using  the  normal  matching function on this data finds only "tang".)
390           The longest matching string is always given first (and numbered  zero).
391    
392           If  /gP  is  present  on  the  pattern,  the search for further matches
393           resumes at the end of the longest match. For example:
394    
395               re> /(tang|tangerine|tan)/g
396             data> yellow tangerine and tangy sultana\D
397              0: tangerine
398              1: tang
399              2: tan
400              0: tang
401              1: tan
402              0: tan
403    
404           Since the matching function does not  support  substring  capture,  the
405           escape  sequences  that  are concerned with captured substrings are not
406           relevant.
407    
408    
409    RESTARTING AFTER A PARTIAL MATCH
410    
411           When the alternative matching function has given the PCRE_ERROR_PARTIAL
412           return,  indicating that the subject partially matched the pattern, you
413           can restart the match with additional subject data by means of  the  \R
414           escape sequence. For example:
415    
416               re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/
417             data> 23ja\P\D
418             Partial match: 23ja
419             data> n05\R\D
420              0: n05
421    
422           For  further  information  about  partial matching, see the pcrepartial
423           documentation.
424    
 DATA LINES  
425    
426       Before each data line is passed to pcre_exec(), leading  and  CALLOUTS
427       trailing whitespace is removed, and it is then scanned for \  
428       escapes.  Some  of  these  are  pretty  esoteric   features,         If the pattern contains any callout requests, pcretest's callout  func-
429       intended  for  checking  out  some  of  the more complicated         tion  is  called  during  matching. This works with both matching func-
430       features of PCRE. If you are just testing "ordinary" regular         tions. By default, the called function displays the callout number, the
431       expressions,  you probably don't need any of these. The fol-         start  and  current  positions in the text at the callout time, and the
432       lowing escapes are recognized:         next pattern item to be tested. For example, the output
433    
434         \a         alarm (= BEL)           --->pqrabcdef
435         \b         backspace             0    ^  ^     \d
436         \e         escape  
437         \f         formfeed         indicates that callout number 0 occurred for a match  attempt  starting
438         \n         newline         at  the fourth character of the subject string, when the pointer was at
439         \r         carriage return         the seventh character of the data, and when the next pattern  item  was
440         \t         tab         \d.  Just  one  circumflex is output if the start and current positions
441         \v         vertical tab         are the same.
442         \nnn       octal character (up to 3 octal digits)  
443         \xhh       hexadecimal character (up to 2 hex digits)         Callouts numbered 255 are assumed to be automatic callouts, inserted as
444         \x{hh...}  hexadecimal character, any number of digits         a  result  of the /C pattern modifier. In this case, instead of showing
445                      in UTF-8 mode         the callout number, the offset in the pattern, preceded by a  plus,  is
446         \A         pass the PCRE_ANCHORED option to pcre_exec()         output. For example:
447         \B         pass the PCRE_NOTBOL option to pcre_exec()  
448         \Cdd       call pcre_copy_substring() for substring dd             re> /\d?[A-E]\*/C
449                      after a successful match (any decimal number           data> E*
450                      less than 32)           --->E*
451         \Cname     call pcre_copy_named_substring() for substring            +0 ^      \d?
452                      "name" after a successful match (name termin-            +3 ^      [A-E]
453                      ated by next non alphanumeric character)            +8 ^^     \*
454         \C+        show the current captured substrings at callout           +10 ^ ^
455                      time            0: E*
456    
457         C-        do not supply a callout function         The  callout  function  in pcretest returns zero (carry on matching) by
458         \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)
459                      reached         to change this.
460         \C!n!m     return 1 instead of 0 when callout number n is  
461                      reached for the nth time         Inserting  callouts can be helpful when using pcretest to check compli-
462         \C*n       pass the number n (may be negative) as callout         cated regular expressions. For further information about callouts,  see
463                      data         the pcrecallout documentation.
464         \Gdd       call pcre_get_substring() for substring dd  
465                      after a successful match (any decimal number  
466                      less than 32)  SAVING AND RELOADING COMPILED PATTERNS
467         \Gname     call pcre_get_named_substring() for substring  
468                      "name" after a successful match (name termin-         The  facilities  described  in  this section are not available when the
469                      ated by next non-alphanumeric character)         POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
470         \L         call pcre_get_substringlist() after a         ifier is specified.
471                      successful match  
472         \M         discover the minimum MATCH_LIMIT setting         When the POSIX interface is not in use, you can cause pcretest to write
473         \N         pass the PCRE_NOTEMPTY option to pcre_exec()         a compiled pattern to a file, by following the modifiers with >  and  a
474         \Odd       set the size of the output vector passed to         file name.  For example:
475                      pcre_exec() to dd (any number of decimal  
476                      digits)           /pattern/im >/some/file
477         \Z         pass the PCRE_NOTEOL option to pcre_exec()  
478           See  the pcreprecompile documentation for a discussion about saving and
479       If \M is present, pcretest calls pcre_exec() several  times,         re-using compiled patterns.
480       with  different  values  in  the  match_limit  field  of the  
481       pcre_extra data structure, until it finds the minimum number         The data that is written is binary.  The  first  eight  bytes  are  the
482       that is needed for pcre_exec() to complete. This number is a         length  of  the  compiled  pattern  data  followed by the length of the
483       measure of the amount of  recursion  and  backtracking  that         optional study data, each written as four  bytes  in  big-endian  order
484       takes  place,  and  checking  it out can be instructive. For         (most  significant  byte  first). If there is no study data (either the
485       most simple matches, the number is quite small, but for pat-         pattern was not studied, or studying did not return any data), the sec-
486       terns  with very large numbers of matching possibilities, it         ond  length  is  zero. The lengths are followed by an exact copy of the
487       can become large very quickly with increasing length of sub-         compiled pattern. If there is additional study data, this follows imme-
488       ject string.         diately  after  the  compiled pattern. After writing the file, pcretest
489           expects to read a new pattern.
490       When \O is used, it may be higher or lower than the size set  
491       by  the  -O  option (or defaulted to 45); \O applies only to         A saved pattern can be reloaded into pcretest by specifing < and a file
492       the call of pcre_exec() for the line in which it appears.         name  instead  of  a pattern. The name of the file must not contain a <
493           character, as otherwise pcretest will interpret the line as  a  pattern
494       A backslash followed by anything else just escapes the  any-         delimited by < characters.  For example:
495       thing else. If the very last character is a backslash, it is  
496       ignored. This gives a way of passing an empty line as  data,            re> </some/file
497       since a real empty line terminates the data input.           Compiled regex loaded from /some/file
498             No study data
499       If /P was present on the regex, causing  the  POSIX  wrapper  
500       API  to  be  used,  only  B,  and Z have any effect, causing         When  the pattern has been loaded, pcretest proceeds to read data lines
501       REG_NOTBOL and REG_NOTEOL to be passed to regexec()  respec-         in the usual way.
502       tively.  
503           You can copy a file written by pcretest to a different host and  reload
504       The use of \x{hh...} to represent UTF-8  characters  is  not         it  there,  even  if the new host has opposite endianness to the one on
505       dependent  on  the use of the /8 modifier on the pattern. It         which the pattern was compiled. For example, you can compile on an  i86
506       is recognized always. There may be any number of hexadecimal         machine and run on a SPARC machine.
507       digits  inside  the  braces.  The  result is from one to six  
508       bytes, encoded according to the UTF-8 rules.         File  names  for  saving and reloading can be absolute or relative, but
509           note that the shell facility of expanding a file name that starts  with
510           a tilde (~) is not available.
511  OUTPUT FROM PCRETEST  
512           The  ability to save and reload files in pcretest is intended for test-
513       When a match succeeds, pcretest outputs the list of captured         ing and experimentation. It is not intended for production use  because
514       substrings  that pcre_exec() returns, starting with number 0         only  a  single pattern can be written to a file. Furthermore, there is
515       for the string that matched the whole pattern.  Here  is  an         no facility for supplying  custom  character  tables  for  use  with  a
516       example of an interactive pcretest run.         reloaded  pattern.  If  the  original  pattern was compiled with custom
517           tables, an attempt to match a subject string using a  reloaded  pattern
518         $ pcretest         is  likely to cause pcretest to crash.  Finally, if you attempt to load
519         PCRE version 4.00 08-Jan-2003         a file that is not in the correct format, the result is undefined.
   
          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.  
520    
521    
522  AUTHOR  AUTHOR
523    
524       Philip Hazel <ph10@cam.ac.uk>         Philip Hazel
525       University Computing Service,         University Computing Service,
526       Cambridge CB2 3QG, England.         Cambridge CB2 3QG, England.
527    
528  Last updated: 03 February 2003  Last updated: 28 February 2005
529  Copyright (c) 1997-2003 University of Cambridge.  Copyright (c) 1997-2005 University of Cambridge.

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