/[pcre]/code/trunk/doc/pcretest.txt
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revision 79 by nigel, Sat Feb 24 21:40:52 2007 UTC revision 461 by ph10, Mon Oct 5 10:59:35 2009 UTC
# Line 7  NAME Line 7  NAME
7    
8  SYNOPSIS  SYNOPSIS
9    
10         pcretest [-C] [-d] [-dfa] [-i] [-m] [-o osize] [-p] [-t] [source]         pcretest [options] [source] [destination]
             [destination]  
11    
12         pcretest  was written as a test program for the PCRE regular expression         pcretest  was written as a test program for the PCRE regular expression
13         library itself, but it can also be used for experimenting with  regular         library itself, but it can also be used for experimenting with  regular
# Line 20  SYNOPSIS Line 19  SYNOPSIS
19    
20  OPTIONS  OPTIONS
21    
22           -b        Behave as if each regex has the /B (show bytecode)  modifier;
23                     the internal form is output after compilation.
24    
25         -C        Output the version number of the PCRE library, and all avail-         -C        Output the version number of the PCRE library, and all avail-
26                   able   information  about  the  optional  features  that  are                   able  information  about  the  optional  features  that   are
27                   included, and then exit.                   included, and then exit.
28    
29         -d        Behave as if each regex has  the  /D  (debug)  modifier;  the         -d        Behave  as  if  each  regex  has the /D (debug) modifier; the
30                   internal form is output after compilation.                   internal form and information about the compiled  pattern  is
31                     output after compilation; -d is equivalent to -b -i.
32    
33         -dfa      Behave  as if each data line contains the \D escape sequence;         -dfa      Behave  as if each data line contains the \D escape sequence;
34                   this    causes    the    alternative    matching    function,                   this    causes    the    alternative    matching    function,
35                   pcre_dfa_exec(),   to   be   used  instead  of  the  standard                   pcre_dfa_exec(),   to   be   used  instead  of  the  standard
36                   pcre_exec() function (more detail is given below).                   pcre_exec() function (more detail is given below).
37    
38           -help     Output a brief summary these options and then exit.
39    
40         -i        Behave as if each regex  has  the  /I  modifier;  information         -i        Behave as if each regex  has  the  /I  modifier;  information
41                   about the compiled pattern is given after compilation.                   about the compiled pattern is given after compilation.
42    
43         -m        Output  the  size  of each compiled pattern after it has been         -M        Behave  as if each data line contains the \M escape sequence;
44                   compiled. This is equivalent to adding  /M  to  each  regular                   this causes PCRE to  discover  the  minimum  MATCH_LIMIT  and
45                   expression.   For  compatibility  with  earlier  versions  of                   MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
46                     edly with different limits.
47    
48           -m        Output the size of each compiled pattern after  it  has  been
49                     compiled.  This  is  equivalent  to adding /M to each regular
50                     expression.  For  compatibility  with  earlier  versions   of
51                   pcretest, -s is a synonym for -m.                   pcretest, -s is a synonym for -m.
52    
53         -o osize  Set the number of elements in the output vector that is  used         -o osize  Set  the number of elements in the output vector that is used
54                   when  calling  pcre_exec()  to be osize. The default value is                   when calling pcre_exec() or pcre_dfa_exec() to be osize.  The
55                   45, which is enough for 14 capturing subexpressions. The vec-                   default  value is 45, which is enough for 14 capturing subex-
56                   tor  size  can  be  changed  for individual matching calls by                   pressions  for  pcre_exec()  or  22  different  matches   for
57                   including \O in the data line (see below).                   pcre_dfa_exec().  The vector size can be changed for individ-
58                     ual matching calls by including \O  in  the  data  line  (see
59                     below).
60    
61         -p        Behave as if each regex has the /P modifier; the POSIX  wrap-         -p        Behave  as if each regex has the /P modifier; the POSIX wrap-
62                   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
63                   any effect when -p is set.                   any effect when -p is set.
64    
65         -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
66                   and  output resulting time per compile or match (in millisec-                   execution.
67                   onds). Do not set -m with -t, because you will then  get  the  
68                   size  output  a  zillion  times,  and the timing will be dis-         -S size   On Unix-like systems, set the size of the  runtime  stack  to
69                   torted.                   size megabytes.
70    
71           -t        Run  each  compile, study, and match many times with a timer,
72                     and output resulting time per compile or match (in  millisec-
73                     onds).  Do  not set -m with -t, because you will then get the
74                     size output a zillion times, and  the  timing  will  be  dis-
75                     torted.  You  can  control  the number of iterations that are
76                     used for timing by following -t with a number (as a  separate
77                     item on the command line). For example, "-t 1000" would iter-
78                     ate 1000 times. The default is to iterate 500000 times.
79    
80           -tm       This is like -t except that it times only the matching phase,
81                     not the compile or study phases.
82    
83    
84  DESCRIPTION  DESCRIPTION
85    
86         If pcretest is given two filename arguments, it reads  from  the  first         If  pcretest  is  given two filename arguments, it reads from the first
87         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
88         reads from that file and writes to stdout.  Otherwise,  it  reads  from         reads  from  that  file  and writes to stdout. Otherwise, it reads from
89         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
90         "re>" to prompt for regular expressions, and "data>" to prompt for data         "re>" to prompt for regular expressions, and "data>" to prompt for data
91         lines.         lines.
92    
93           When pcretest is built, a configuration  option  can  specify  that  it
94           should  be  linked  with the libreadline library. When this is done, if
95           the input is from a terminal, it is read using the readline() function.
96           This  provides line-editing and history facilities. The output from the
97           -help option states whether or not readline() will be used.
98    
99         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.
100         Each set starts with a regular expression, and continues with any  num-         Each  set starts with a regular expression, and continues with any num-
101         ber of data lines to be matched against the pattern.         ber of data lines to be matched against the pattern.
102    
103         Each  data line is matched separately and independently. If you want to         Each data line is matched separately and independently. If you want  to
104         do multiple-line matches, you have to use the \n escape sequence  in  a         do multi-line matches, you have to use the \n escape sequence (or \r or
105         single  line  of  input  to  encode the newline characters. The maximum         \r\n, etc., depending on the newline setting) in a single line of input
106         length of data line is 30,000 characters.         to  encode  the  newline  sequences. There is no limit on the length of
107           data lines; the input buffer is automatically extended  if  it  is  too
108         An empty line signals the end of the data lines, at which point  a  new         small.
109         regular  expression is read. The regular expressions are given enclosed  
110         in any non-alphanumeric delimiters other than backslash, for example         An  empty  line signals the end of the data lines, at which point a new
111           regular expression is read. The regular expressions are given  enclosed
112           in any non-alphanumeric delimiters other than backslash, for example:
113    
114           /(a|bc)x+yz/           /(a|bc)x+yz/
115    
116         White space before the initial delimiter is ignored. A regular  expres-         White  space before the initial delimiter is ignored. A regular expres-
117         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-
118         line characters are included within it. It is possible to  include  the         line  characters  are included within it. It is possible to include the
119         delimiter within the pattern by escaping it, for example         delimiter within the pattern by escaping it, for example
120    
121           /abc\/def/           /abc\/def/
122    
123         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,
124         but since delimiters are always non-alphanumeric, this does not  affect         but  since delimiters are always non-alphanumeric, this does not affect
125         its  interpretation.   If the terminating delimiter is immediately fol-         its interpretation.  If the terminating delimiter is  immediately  fol-
126         lowed by a backslash, for example,         lowed by a backslash, for example,
127    
128           /abc/\           /abc/\
129    
130         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
131         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
132         finishes with a backslash, because         finishes with a backslash, because
133    
134           /abc\/           /abc\/
135    
136         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/",
137         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
138         expression.         expression.
139    
140    
141  PATTERN MODIFIERS  PATTERN MODIFIERS
142    
143         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
144         single  characters.  Following  Perl usage, these are referred to below         single characters. Following Perl usage, these are  referred  to  below
145         as, for example, "the /i modifier", even though the  delimiter  of  the         as,  for  example,  "the /i modifier", even though the delimiter of the
146         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
147         modifiers. Whitespace may appear between the  final  pattern  delimiter         modifiers.  Whitespace  may  appear between the final pattern delimiter
148         and the first modifier, and between the modifiers themselves.         and the first modifier, and between the modifiers themselves.
149    
150         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,
151         PCRE_DOTALL, or PCRE_EXTENDED  options,  respectively,  when  pcre_com-         PCRE_DOTALL,  or  PCRE_EXTENDED  options,  respectively, when pcre_com-
152         pile()  is  called. These four modifier letters have the same effect as         pile() is called. These four modifier letters have the same  effect  as
153         they do in Perl. For example:         they do in Perl. For example:
154    
155           /caseless/i           /caseless/i
# Line 125  PATTERN MODIFIERS Line 157  PATTERN MODIFIERS
157         The following table shows additional modifiers for setting PCRE options         The following table shows additional modifiers for setting PCRE options
158         that do not correspond to anything in Perl:         that do not correspond to anything in Perl:
159    
160           /A    PCRE_ANCHORED           /A              PCRE_ANCHORED
161           /C    PCRE_AUTO_CALLOUT           /C              PCRE_AUTO_CALLOUT
162           /E    PCRE_DOLLAR_ENDONLY           /E              PCRE_DOLLAR_ENDONLY
163           /f    PCRE_FIRSTLINE           /f              PCRE_FIRSTLINE
164           /N    PCRE_NO_AUTO_CAPTURE           /J              PCRE_DUPNAMES
165           /U    PCRE_UNGREEDY           /N              PCRE_NO_AUTO_CAPTURE
166           /X    PCRE_EXTRA           /U              PCRE_UNGREEDY
167             /X              PCRE_EXTRA
168             /<JS>           PCRE_JAVASCRIPT_COMPAT
169             /<cr>           PCRE_NEWLINE_CR
170             /<lf>           PCRE_NEWLINE_LF
171             /<crlf>         PCRE_NEWLINE_CRLF
172             /<anycrlf>      PCRE_NEWLINE_ANYCRLF
173             /<any>          PCRE_NEWLINE_ANY
174             /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
175             /<bsr_unicode>  PCRE_BSR_UNICODE
176    
177           Those specifying line ending sequences are literal  strings  as  shown,
178           but  the  letters  can  be  in either case. This example sets multiline
179           matching with CRLF as the line ending sequence:
180    
181             /^abc/m<crlf>
182    
183           Details of the meanings of these PCRE options are given in the  pcreapi
184           documentation.
185    
186       Finding all matches in a string
187    
188         Searching  for  all  possible matches within each subject string can be         Searching  for  all  possible matches within each subject string can be
189         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
# Line 144  PATTERN MODIFIERS Line 196  PATTERN MODIFIERS
196         or \B).         or \B).
197    
198         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
199         string, the next call is done with the PCRE_NOTEMPTY and  PCRE_ANCHORED         string, the next  call  is  done  with  the  PCRE_NOTEMPTY_ATSTART  and
200         flags  set in order to search for another, non-empty, match at the same         PCRE_ANCHORED  flags  set  in  order  to search for another, non-empty,
201         point.  If this second match fails, the start  offset  is  advanced  by         match at the same point. If this second match fails, the  start  offset
202         one,  and  the normal match is retried. This imitates the way Perl han-         is  advanced  by  one  character, and the normal match is retried. This
203         dles such cases when using the /g modifier or the split() function.         imitates the way Perl handles such cases when using the /g modifier  or
204           the split() function.
205    
206       Other modifiers
207    
208         There are yet more modifiers for controlling the way pcretest operates.         There are yet more modifiers for controlling the way pcretest operates.
209    
# Line 157  PATTERN MODIFIERS Line 212  PATTERN MODIFIERS
212         remainder  of  the  subject  string. This is useful for tests where the         remainder  of  the  subject  string. This is useful for tests where the
213         subject contains multiple copies of the same substring.         subject contains multiple copies of the same substring.
214    
215         The /L modifier must be followed directly by the name of a locale,  for         The /B modifier is a debugging feature. It requests that pcretest  out-
216           put  a representation of the compiled byte code after compilation. Nor-
217           mally this information contains length and offset values;  however,  if
218           /Z  is also present, this data is replaced by spaces. This is a special
219           feature for use in the automatic test scripts; it ensures that the same
220           output is generated for different internal link sizes.
221    
222           The  /L modifier must be followed directly by the name of a locale, for
223         example,         example,
224    
225           /pattern/Lfr_FR           /pattern/Lfr_FR
226    
227         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,
228         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
229         locale,  and  this  is then passed to pcre_compile() when compiling the         locale, and this is then passed to pcre_compile()  when  compiling  the
230         regular expression. Without an /L  modifier,  NULL  is  passed  as  the         regular  expression.  Without  an  /L  modifier,  NULL is passed as the
231         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
232         appears.         appears.
233    
234         The /I modifier requests that pcretest  output  information  about  the         The  /I  modifier  requests  that pcretest output information about the
235         compiled  pattern (whether it is anchored, has a fixed first character,         compiled pattern (whether it is anchored, has a fixed first  character,
236         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
237         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-
238         put.         put.
239    
240         The /D modifier is a PCRE debugging feature, which also assumes /I.  It         The  /D modifier is a PCRE debugging feature, and is equivalent to /BI,
241         causes  the  internal form of compiled regular expressions to be output         that is, both the /B and the /I modifiers.
        after compilation. If the pattern was studied, the information returned  
        is also output.  
242    
243         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
244         the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This         the  compiled  pattern  that  contain  2-byte  and 4-byte numbers. This
245         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
246         patterns that were compiled on a host with a different endianness. This         patterns that were compiled on a host with a different endianness. This
247         feature  is  not  available  when  the POSIX interface to PCRE is being         feature is not available when the POSIX  interface  to  PCRE  is  being
248         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
249         section about saving and reloading compiled patterns below.         section about saving and reloading compiled patterns below.
250    
251         The  /S  modifier causes pcre_study() to be called after the expression         The /S modifier causes pcre_study() to be called after  the  expression
252         has been compiled, and the results used when the expression is matched.         has been compiled, and the results used when the expression is matched.
253    
254         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-
# Line 198  PATTERN MODIFIERS Line 258  PATTERN MODIFIERS
258         rather  than  its  native  API.  When this is done, all other modifiers         rather  than  its  native  API.  When this is done, all other modifiers
259         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,
260         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
261         PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is  set.         PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
262    
263         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
264         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-
265         vided  that  it  was  compiled with this support enabled. This modifier         vided that it was compiled with this  support  enabled.  This  modifier
266         also causes any non-printing characters in output strings to be printed         also causes any non-printing characters in output strings to be printed
267         using the \x{hh...} notation if they are valid UTF-8 sequences.         using the \x{hh...} notation if they are valid UTF-8 sequences.
268    
269         If  the  /?  modifier  is  used  with  /8,  it  causes pcretest to call         If the /? modifier  is  used  with  /8,  it  causes  pcretest  to  call
270         pcre_compile() with the  PCRE_NO_UTF8_CHECK  option,  to  suppress  the         pcre_compile()  with  the  PCRE_NO_UTF8_CHECK  option,  to suppress the
271         checking of the string for UTF-8 validity.         checking of the string for UTF-8 validity.
272    
273    
274  DATA LINES  DATA LINES
275    
276         Before  each  data  line is passed to pcre_exec(), leading and trailing         Before each data line is passed to pcre_exec(),  leading  and  trailing
277         whitespace is removed, and it is then scanned for \  escapes.  Some  of         whitespace  is  removed,  and it is then scanned for \ escapes. Some of
278         these  are  pretty esoteric features, intended for checking out some of         these are pretty esoteric features, intended for checking out  some  of
279         the more complicated features of PCRE. If you are just  testing  "ordi-         the  more  complicated features of PCRE. If you are just testing "ordi-
280         nary"  regular  expressions,  you probably don't need any of these. The         nary" regular expressions, you probably don't need any  of  these.  The
281         following escapes are recognized:         following escapes are recognized:
282    
283           \a         alarm (= BEL)           \a         alarm (BEL, \x07)
284           \b         backspace           \b         backspace (\x08)
285           \e         escape           \e         escape (\x27)
286           \f         formfeed           \f         formfeed (\x0c)
287           \n         newline           \n         newline (\x0a)
288           \r         carriage return           \qdd       set the PCRE_MATCH_LIMIT limit to dd
289           \t         tab                        (any number of digits)
290           \v         vertical tab           \r         carriage return (\x0d)
291             \t         tab (\x09)
292             \v         vertical tab (\x0b)
293           \nnn       octal character (up to 3 octal digits)           \nnn       octal character (up to 3 octal digits)
294           \xhh       hexadecimal character (up to 2 hex digits)           \xhh       hexadecimal character (up to 2 hex digits)
295           \x{hh...}  hexadecimal character, any number of digits           \x{hh...}  hexadecimal character, any number of digits
296                        in UTF-8 mode                        in UTF-8 mode
297           \A         pass the PCRE_ANCHORED option to pcre_exec()           \A         pass the PCRE_ANCHORED option to pcre_exec()
298                          or pcre_dfa_exec()
299           \B         pass the PCRE_NOTBOL option to pcre_exec()           \B         pass the PCRE_NOTBOL option to pcre_exec()
300                          or pcre_dfa_exec()
301           \Cdd       call pcre_copy_substring() for substring dd           \Cdd       call pcre_copy_substring() for substring dd
302                        after a successful match (number less than 32)                        after a successful match (number less than 32)
303           \Cname     call pcre_copy_named_substring() for substring           \Cname     call pcre_copy_named_substring() for substring
# Line 257  DATA LINES Line 321  DATA LINES
321                        ated by next non-alphanumeric character)                        ated by next non-alphanumeric character)
322           \L         call pcre_get_substringlist() after a           \L         call pcre_get_substringlist() after a
323                        successful match                        successful match
324           \M         discover the minimum MATCH_LIMIT setting           \M         discover the minimum MATCH_LIMIT and
325                          MATCH_LIMIT_RECURSION settings
326           \N         pass the PCRE_NOTEMPTY option to pcre_exec()           \N         pass the PCRE_NOTEMPTY option to pcre_exec()
327                          or pcre_dfa_exec(); if used twice, pass the
328                          PCRE_NOTEMPTY_ATSTART option
329           \Odd       set the size of the output vector passed to           \Odd       set the size of the output vector passed to
330                        pcre_exec() to dd (any number of digits)                        pcre_exec() to dd (any number of digits)
331           \P         pass the PCRE_PARTIAL option to pcre_exec()           \P         pass the PCRE_PARTIAL_SOFT option to pcre_exec()
332                        or pcre_dfa_exec()                        or pcre_dfa_exec(); if used twice, pass the
333                          PCRE_PARTIAL_HARD option
334             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
335                          (any number of digits)
336           \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()           \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
337           \S         output details of memory get/free calls during matching           \S         output details of memory get/free calls during matching
338             \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
339                          or pcre_dfa_exec()
340           \Z         pass the PCRE_NOTEOL option to pcre_exec()           \Z         pass the PCRE_NOTEOL option to pcre_exec()
341                          or pcre_dfa_exec()
342           \?         pass the PCRE_NO_UTF8_CHECK option to           \?         pass the PCRE_NO_UTF8_CHECK option to
343                        pcre_exec()                        pcre_exec() or pcre_dfa_exec()
344           \>dd       start the match at offset dd (any number of digits);           \>dd       start the match at offset dd (any number of digits);
345                        this sets the startoffset argument for pcre_exec()                        this sets the startoffset argument for pcre_exec()
346                          or pcre_dfa_exec()
347             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
348                          or pcre_dfa_exec()
349             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
350                          or pcre_dfa_exec()
351             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
352                          or pcre_dfa_exec()
353             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
354                          or pcre_dfa_exec()
355             \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()
356                          or pcre_dfa_exec()
357    
358         A backslash followed by anything else just escapes the  anything  else.         The  escapes  that  specify  line ending sequences are literal strings,
359         If  the very last character is a backslash, it is ignored. This gives a         exactly as shown. No more than one newline setting should be present in
360         way of passing an empty line as data, since a real  empty  line  termi-         any data line.
361    
362           A  backslash  followed by anything else just escapes the anything else.
363           If the very last character is a backslash, it is ignored. This gives  a
364           way  of  passing  an empty line as data, since a real empty line termi-
365         nates the data input.         nates the data input.
366    
367         If  \M  is present, pcretest calls pcre_exec() several times, with dif-         If \M is present, pcretest calls pcre_exec() several times,  with  dif-
368         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
369         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
370         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-
371         backtracking  that takes place, and checking it out can be instructive.         ber is a measure of the amount of backtracking that  takes  place,  and
372         For most simple matches, the number is quite small,  but  for  patterns         checking it out can be instructive. For most simple matches, the number
373         with  very large numbers of matching possibilities, it can become large         is quite small, but for patterns with very large  numbers  of  matching
374         very quickly with increasing length of subject string.         possibilities,  it can become large very quickly with increasing length
375           of subject string. The match_limit_recursion number is a measure of how
376           much  stack  (or,  if  PCRE is compiled with NO_RECURSE, how much heap)
377           memory is needed to complete the match attempt.
378    
379         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
380         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
381         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.
382    
383         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-
384         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
385         and REG_NOTEOL to be passed to regexec() respectively.         effect are \B and \Z, causing REG_NOTBOL and REG_NOTEOL,  respectively,
386           to be passed to regexec().
387         The use of \x{hh...} to represent UTF-8 characters is not dependent  on  
388         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
389         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.
390         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
391           result is from one to six bytes,  encoded  according  to  the  original
392           UTF-8  rules  of  RFC  2279.  This  allows for values in the range 0 to
393           0x7FFFFFFF. Note that not all of those are valid Unicode  code  points,
394           or  indeed  valid  UTF-8 characters according to the later rules in RFC
395           3629.
396    
397    
398  THE ALTERNATIVE MATCHING FUNCTION  THE ALTERNATIVE MATCHING FUNCTION
# Line 321  DEFAULT OUTPUT FROM PCRETEST Line 417  DEFAULT OUTPUT FROM PCRETEST
417    
418         When a match succeeds, pcretest outputs the list of captured substrings         When a match succeeds, pcretest outputs the list of captured substrings
419         that pcre_exec() returns, starting with number 0 for  the  string  that         that pcre_exec() returns, starting with number 0 for  the  string  that
420         matched the whole pattern. Otherwise, it outputs "No match" or "Partial         matched  the  whole  pattern. Otherwise, it outputs "No match" when the
421         match" when pcre_exec() returns PCRE_ERROR_NOMATCH  or  PCRE_ERROR_PAR-         return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
422         TIAL,  respectively, and otherwise the PCRE negative error number. Here         tially  matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
423           For any other returns, it outputs the PCRE negative error number.  Here
424         is an example of an interactive pcretest run.         is an example of an interactive pcretest run.
425    
426           $ pcretest           $ pcretest
427           PCRE version 5.00 07-Sep-2004           PCRE version 7.0 30-Nov-2006
428    
429             re> /^abc(\d+)/             re> /^abc(\d+)/
430           data> abc123           data> abc123
# Line 336  DEFAULT OUTPUT FROM PCRETEST Line 433  DEFAULT OUTPUT FROM PCRETEST
433           data> xyz           data> xyz
434           No match           No match
435    
436           Note  that unset capturing substrings that are not followed by one that
437           is set are not returned by pcre_exec(), and are not shown by  pcretest.
438           In  the following example, there are two capturing substrings, but when
439           the first data line is matched, the  second,  unset  substring  is  not
440           shown.  An "internal" unset substring is shown as "<unset>", as for the
441           second data line.
442    
443               re> /(a)|(b)/
444             data> a
445              0: a
446              1: a
447             data> b
448              0: b
449              1: <unset>
450              2: b
451    
452         If the strings contain any non-printing characters, they are output  as         If the strings contain any non-printing characters, they are output  as
453         \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
454         the pattern. If the pattern has the /+ modifier, the  output  for  sub-         the pattern. See below for the definition of  non-printing  characters.
455         string  0 is followed by the the rest of the subject string, identified         If  the pattern has the /+ modifier, the output for substring 0 is fol-
456         by "0+" like this:         lowed by the the rest of the subject string, identified  by  "0+"  like
457           this:
458    
459             re> /cat/+             re> /cat/+
460           data> cataract           data> cataract
461            0: cat            0: cat
462            0+ aract            0+ aract
463    
464         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
465         matching attempts are output in sequence, like this:         matching attempts are output in sequence, like this:
466    
467             re> /\Bi(\w\w)/g             re> /\Bi(\w\w)/g
# Line 361  DEFAULT OUTPUT FROM PCRETEST Line 475  DEFAULT OUTPUT FROM PCRETEST
475    
476         "No match" is output only if the first match attempt fails.         "No match" is output only if the first match attempt fails.
477    
478         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
479         is successfully matched, the substrings extracted  by  the  convenience         is  successfully  matched,  the substrings extracted by the convenience
480         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
481         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
482         (that  is,  the return from the extraction function) is given in paren-         (that is, the return from the extraction function) is given  in  paren-
483         theses after each string for \C and \G.         theses after each string for \C and \G.
484    
485         Note that while patterns can be continued over several lines  (a  plain         Note that whereas patterns can be continued over several lines (a plain
486         ">" prompt is used for continuations), data lines may not. However new-         ">" prompt is used for continuations), data lines may not. However new-
487         lines can be included in data by means of the \n escape.         lines  can  be included in data by means of the \n escape (or \r, \r\n,
488           etc., depending on the newline sequence setting).
489    
490    
491  OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION  OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
# Line 388  OUTPUT FROM THE ALTERNATIVE MATCHING FUN Line 503  OUTPUT FROM THE ALTERNATIVE MATCHING FUN
503    
504         (Using  the  normal  matching function on this data finds only "tang".)         (Using  the  normal  matching function on this data finds only "tang".)
505         The longest matching string is always given first (and numbered  zero).         The longest matching string is always given first (and numbered  zero).
506           After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
507           lowed by the partially matching substring.
508    
509         If  /gP  is  present  on  the  pattern,  the search for further matches         If /g is present on the pattern, the search for further matches resumes
510         resumes at the end of the longest match. For example:         at the end of the longest match. For example:
511    
512             re> /(tang|tangerine|tan)/g             re> /(tang|tangerine|tan)/g
513           data> yellow tangerine and tangy sultana\D           data> yellow tangerine and tangy sultana\D
# Line 401  OUTPUT FROM THE ALTERNATIVE MATCHING FUN Line 518  OUTPUT FROM THE ALTERNATIVE MATCHING FUN
518            1: tan            1: tan
519            0: tan            0: tan
520    
521         Since the matching function does not  support  substring  capture,  the         Since  the  matching  function  does not support substring capture, the
522         escape  sequences  that  are concerned with captured substrings are not         escape sequences that are concerned with captured  substrings  are  not
523         relevant.         relevant.
524    
525    
526  RESTARTING AFTER A PARTIAL MATCH  RESTARTING AFTER A PARTIAL MATCH
527    
528         When the alternative matching function has given the PCRE_ERROR_PARTIAL         When the alternative matching function has given the PCRE_ERROR_PARTIAL
529         return,  indicating that the subject partially matched the pattern, you         return, indicating that the subject partially matched the pattern,  you
530         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
531         escape sequence. For example:         escape sequence. For example:
532    
533             re> /^?(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)$/             re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
534           data> 23ja\P\D           data> 23ja\P\D
535           Partial match: 23ja           Partial match: 23ja
536           data> n05\R\D           data> n05\R\D
537            0: n05            0: n05
538    
539         For  further  information  about  partial matching, see the pcrepartial         For further information about partial  matching,  see  the  pcrepartial
540         documentation.         documentation.
541    
542    
543  CALLOUTS  CALLOUTS
544    
545         If the pattern contains any callout requests, pcretest's callout  func-         If  the pattern contains any callout requests, pcretest's callout func-
546         tion  is  called  during  matching. This works with both matching func-         tion is called during matching. This works  with  both  matching  func-
547         tions. By default, the called function displays the callout number, the         tions. By default, the called function displays the callout number, the
548         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
549         next pattern item to be tested. For example, the output         next pattern item to be tested. For example, the output
550    
551           --->pqrabcdef           --->pqrabcdef
552             0    ^  ^     \d             0    ^  ^     \d
553    
554         indicates that callout number 0 occurred for a match  attempt  starting         indicates  that  callout number 0 occurred for a match attempt starting
555         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
556         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
557         \d.  Just  one  circumflex is output if the start and current positions         \d. Just one circumflex is output if the start  and  current  positions
558         are the same.         are the same.
559    
560         Callouts numbered 255 are assumed to be automatic callouts, inserted as         Callouts numbered 255 are assumed to be automatic callouts, inserted as
561         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
562         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
563         output. For example:         output. For example:
564    
565             re> /\d?[A-E]\*/C             re> /\d?[A-E]\*/C
# Line 454  CALLOUTS Line 571  CALLOUTS
571           +10 ^ ^           +10 ^ ^
572            0: E*            0: E*
573    
574         The  callout  function  in pcretest returns zero (carry on matching) by         The callout function in pcretest returns zero (carry  on  matching)  by
575         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)
576         to change this.         to change this.
577    
578         Inserting  callouts can be helpful when using pcretest to check compli-         Inserting callouts can be helpful when using pcretest to check  compli-
579         cated regular expressions. For further information about callouts,  see         cated  regular expressions. For further information about callouts, see
580         the pcrecallout documentation.         the pcrecallout documentation.
581    
582    
583    NON-PRINTING CHARACTERS
584    
585           When pcretest is outputting text in the compiled version of a  pattern,
586           bytes  other  than 32-126 are always treated as non-printing characters
587           are are therefore shown as hex escapes.
588    
589           When pcretest is outputting text that is a matched part  of  a  subject
590           string,  it behaves in the same way, unless a different locale has been
591           set for the  pattern  (using  the  /L  modifier).  In  this  case,  the
592           isprint() function to distinguish printing and non-printing characters.
593    
594    
595  SAVING AND RELOADING COMPILED PATTERNS  SAVING AND RELOADING COMPILED PATTERNS
596    
597         The  facilities  described  in  this section are not available when the         The  facilities  described  in  this section are not available when the
# Line 519  SAVING AND RELOADING COMPILED PATTERNS Line 648  SAVING AND RELOADING COMPILED PATTERNS
648         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.
649    
650    
651    SEE ALSO
652    
653           pcre(3), pcreapi(3), pcrecallout(3),  pcrematching(3),  pcrepartial(d),
654           pcrepattern(3), pcreprecompile(3).
655    
656    
657  AUTHOR  AUTHOR
658    
659         Philip Hazel         Philip Hazel
660         University Computing Service,         University Computing Service
661         Cambridge CB2 3QG, England.         Cambridge CB2 3QH, England.
662    
663    
664    REVISION
665    
666  Last updated: 28 February 2005         Last updated: 26 September 2009
667  Copyright (c) 1997-2005 University of Cambridge.         Copyright (c) 1997-2009 University of Cambridge.

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