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

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