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1  The pcretest program  PCRETEST(1)                                                        PCRETEST(1)
 --------------------  
2    
 This program is intended for testing PCRE, but it can also be used for  
 experimenting with regular expressions.  
3    
4  If it is given two filename arguments, it reads from the first and writes to  NAME
5  the second. If it is given only one filename argument, it reads from that file         pcretest - a program for testing Perl-compatible regular expressions.
 and writes to stdout. Otherwise, it reads from stdin and writes to stdout, and  
 prompts for each line of input, using "re>" to prompt for regular expressions,  
 and "data>" to prompt for data lines.  
   
 The program handles any number of sets of input on a single input file. Each  
 set starts with a regular expression, and continues with any number of data  
 lines to be matched against the pattern. An empty line signals the end of the  
 data lines, at which point a new regular expression is read. The regular  
 expressions are given enclosed in any non-alphameric delimiters other than  
 backslash, for example  
   
   /(a|bc)x+yz/  
   
 White space before the initial delimiter is ignored. A regular expression may  
 be continued over several input lines, in which case the newline characters are  
 included within it. See the test input files in the testdata directory for many  
 examples. It is possible to include the delimiter within the pattern by  
 escaping it, for example  
   
   /abc\/def/  
   
 If you do so, the escape and the delimiter form part of the pattern, but since  
 delimiters are always non-alphameric, this does not affect its interpretation.  
 If the terminating delimiter is immediately followed by a backslash, for  
 example,  
   
   /abc/\  
   
 then a backslash is added to the end of the pattern. This is done to provide a  
 way of testing the error condition that arises if a pattern finishes with a  
 backslash, because  
   
   /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.  
   
 The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,  
 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For  
 example:  
   
   /caseless/i  
   
 These modifier letters have the same effect as they do in Perl. There are  
 others which set PCRE options that do not correspond to anything in Perl: /A,  
 /E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.  
   
 Searching for all possible matches within each subject string can be requested  
 by the /g or /G modifier. After finding a match, PCRE is called again to search  
 the remainder of the subject string. The difference between /g and /G is that  
 the former uses the startoffset argument to pcre_exec() to start searching at  
 a new point within the entire string (which is in effect what Perl does),  
 whereas the latter passes over a shortened substring. This makes a difference  
 to the matching process if the pattern begins with a lookbehind assertion  
 (including \b or \B).  
   
 If any call to pcre_exec() in a /g or /G sequence matches an empty string, the  
 next call is done with the PCRE_NOTEMPTY and PCRE_ANCHORED flags set in order  
 to search for another, non-empty, match at the same point. If this second match  
 fails, the start offset is advanced by one, and the normal match is retried.  
 This imitates the way Perl handles such cases when using the /g modifier or the  
 split() function.  
   
 There are a number of other modifiers for controlling the way pcretest  
 operates.  
   
 The /+ modifier requests that as well as outputting the substring that matched  
 the entire pattern, pcretest should in addition output the remainder of the  
 subject string. This is useful for tests where the subject contains multiple  
 copies of the same substring.  
   
 The /L modifier must be followed directly by the name of a locale, for example,  
   
   /pattern/Lfr  
   
 For this reason, it must be the last modifier letter. The given locale is set,  
 pcre_maketables() is called to build a set of character tables for the locale,  
 and this is then passed to pcre_compile() when compiling the regular  
 expression. Without an /L modifier, NULL is passed as the tables pointer; that  
 is, /L applies only to the expression on which it appears.  
   
 The /I modifier requests that pcretest output information about the compiled  
 expression (whether it is anchored, has a fixed first character, and so on). It  
 does this by calling pcre_fullinfo() after compiling an expression, and  
 outputting the information it gets back. If the pattern is studied, the results  
 of that are also output.  
   
 The /D modifier is a PCRE debugging feature, which also assumes /I. It causes  
 the internal form of compiled regular expressions to be output after  
 compilation.  
   
 The /S modifier causes pcre_study() to be called after the expression has been  
 compiled, and the results used when the expression is matched.  
   
 The /M modifier causes the size of memory block used to hold the compiled  
 pattern to be output.  
   
 Finally, the /P modifier causes pcretest to call PCRE via the POSIX wrapper API  
 rather than its native API. When this is done, all other modifiers except /i,  
 /m, and /+ are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is  
 set if /m is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always,  
 and PCRE_DOTALL unless REG_NEWLINE is set.  
   
 Before each data line is passed to pcre_exec(), leading and trailing whitespace  
 is removed, and it is then scanned for \ escapes. The following are recognized:  
   
   \a     alarm (= BEL)  
   \b     backspace  
   \e     escape  
   \f     formfeed  
   \n     newline  
   \r     carriage return  
   \t     tab  
   \v     vertical tab  
   \nnn   octal character (up to 3 octal digits)  
   \xhh   hexadecimal character (up to 2 hex digits)  
   
   \A     pass the PCRE_ANCHORED option to pcre_exec()  
   \B     pass the PCRE_NOTBOL option to pcre_exec()  
   \Cdd   call pcre_copy_substring() for substring dd after a successful match  
            (any decimal number less than 32)  
   \Gdd   call pcre_get_substring() for substring dd after a successful match  
            (any decimal number less than 32)  
   \L     call pcre_get_substringlist() after a successful match  
   \N     pass the PCRE_NOTEMPTY option to pcre_exec()  
   \Odd   set the size of the output vector passed to pcre_exec() to dd  
            (any number of decimal digits)  
   \Z     pass the PCRE_NOTEOL option to pcre_exec()  
   
 A backslash followed by anything else just escapes the anything 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() respectively.  
   
 When a match succeeds, pcretest outputs the list of captured substrings that  
 pcre_exec() returns, starting with number 0 for the string that matched the  
 whole pattern. Here is an example of an interactive pcretest run.  
   
   $ pcretest  
   PCRE version 2.06 08-Jun-1999  
   
     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. 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 \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 addition 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.  
   
 If the -p option is given to pcretest, it is equivalent to adding /P to each  
 regular expression: the POSIX wrapper API is used to call PCRE. None of the  
 following flags has any effect in this case.  
   
 If the option -d is given to pcretest, it is equivalent to adding /D to each  
 regular expression: the internal form is output after compilation.  
   
 If the option -i is given to pcretest, it is equivalent to adding /I to each  
 regular expression: information about the compiled pattern is given after  
 compilation.  
   
 If the option -m is given to pcretest, it outputs the size of each compiled  
 pattern after it has been compiled. It is equivalent to adding /M to each  
 regular expression. For compatibility with earlier versions of pcretest, -s is  
 a synonym for -m.  
   
 If the -t option is given, each compile, study, and match is run 20000 times  
 while being timed, and the resulting time per compile or match is output in  
 milliseconds. Do not set -t with -s, because you will then get the size output  
 20000 times and the timing will be distorted. If you want to change the number  
 of repetitions used for timing, edit the definition of LOOPREPEAT at the top of  
 pcretest.c  
6    
7  Philip Hazel <ph10@cam.ac.uk>  
8  January 2000  SYNOPSIS
9    
10           pcretest [options] [source] [destination]
11    
12           pcretest  was written as a test program for the PCRE regular expression
13           library itself, but it can also be used for experimenting with  regular
14           expressions.  This document describes the features of the test program;
15           for details of the regular expressions themselves, see the  pcrepattern
16           documentation. For details of the PCRE library function calls and their
17           options, see the pcreapi documentation.
18    
19    
20    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-
26                     able  information  about  the  optional  features  that   are
27                     included, and then exit.
28    
29           -d        Behave  as  if  each  regex  has the /D (debug) modifier; the
30                     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;
34                     this    causes    the    alternative    matching    function,
35                     pcre_dfa_exec(),   to   be   used  instead  of  the  standard
36                     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
41                     about the compiled pattern is given after compilation.
42    
43           -M        Behave  as if each data line contains the \M escape sequence;
44                     this causes PCRE to  discover  the  minimum  MATCH_LIMIT  and
45                     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.
52    
53           -o osize  Set  the number of elements in the output vector that is used
54                     when calling pcre_exec() or pcre_dfa_exec() to be osize.  The
55                     default  value is 45, which is enough for 14 capturing subex-
56                     pressions  for  pcre_exec()  or  22  different  matches   for
57                     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-
62                     per API is used to call PCRE. None of the other  options  has
63                     any effect when -p is set.
64    
65           -q        Do  not output the version number of pcretest at the start of
66                     execution.
67    
68           -S size   On Unix-like systems, set the size of the  runtime  stack  to
69                     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
85    
86           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
88           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
90           "re>" to prompt for regular expressions, and "data>" to prompt for data
91           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.
100           Each  set starts with a regular expression, and continues with any num-
101           ber of data lines to be matched against the pattern.
102    
103           Each data line is matched separately and independently. If you want  to
104           do multi-line matches, you have to use the \n escape sequence (or \r or
105           \r\n, etc., depending on the newline setting) in a single line of input
106           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           small.
109    
110           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/
115    
116           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-
118           line  characters  are included within it. It is possible to include the
119           delimiter within the pattern by escaping it, for example
120    
121             /abc\/def/
122    
123           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
125           its interpretation.  If the terminating delimiter is  immediately  fol-
126           lowed by a backslash, for example,
127    
128             /abc/\
129    
130           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
132           finishes with a backslash, because
133    
134             /abc\/
135    
136           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
138           expression.
139    
140    
141    PATTERN MODIFIERS
142    
143           A  pattern may be followed by any number of modifiers, which are mostly
144           single characters. Following Perl usage, these are  referred  to  below
145           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
147           modifiers.  Whitespace  may  appear between the final pattern delimiter
148           and the first modifier, and between the modifiers themselves.
149    
150           The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
151           PCRE_DOTALL,  or  PCRE_EXTENDED  options,  respectively, when pcre_com-
152           pile() is called. These four modifier letters have the same  effect  as
153           they do in Perl. For example:
154    
155             /caseless/i
156    
157           The  following  table  shows additional modifiers for setting PCRE com-
158           pile-time options that do not correspond to anything in Perl:
159    
160             /8              PCRE_UTF8
161             /?              PCRE_NO_UTF8_CHECK
162             /A              PCRE_ANCHORED
163             /C              PCRE_AUTO_CALLOUT
164             /E              PCRE_DOLLAR_ENDONLY
165             /f              PCRE_FIRSTLINE
166             /J              PCRE_DUPNAMES
167             /N              PCRE_NO_AUTO_CAPTURE
168             /U              PCRE_UNGREEDY
169             /W              PCRE_UCP
170             /X              PCRE_EXTRA
171             /<JS>           PCRE_JAVASCRIPT_COMPAT
172             /<cr>           PCRE_NEWLINE_CR
173             /<lf>           PCRE_NEWLINE_LF
174             /<crlf>         PCRE_NEWLINE_CRLF
175             /<anycrlf>      PCRE_NEWLINE_ANYCRLF
176             /<any>          PCRE_NEWLINE_ANY
177             /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
178             /<bsr_unicode>  PCRE_BSR_UNICODE
179    
180           The modifiers that are enclosed in angle brackets are  literal  strings
181           as  shown,  including  the  angle  brackets,  but the letters can be in
182           either case. This example sets multiline matching with CRLF as the line
183           ending sequence:
184    
185             /^abc/m<crlf>
186    
187           As well as turning on the PCRE_UTF8 option, the /8 modifier also causes
188           any non-printing characters in output strings to be printed  using  the
189           \x{hh...}  notation  if they are valid UTF-8 sequences. Full details of
190           the PCRE options are given in the pcreapi documentation.
191    
192       Finding all matches in a string
193    
194           Searching for all possible matches within each subject  string  can  be
195           requested  by  the  /g  or  /G modifier. After finding a match, PCRE is
196           called again to search the remainder of the subject string. The differ-
197           ence between /g and /G is that the former uses the startoffset argument
198           to pcre_exec() to start searching at a  new  point  within  the  entire
199           string  (which  is in effect what Perl does), whereas the latter passes
200           over a shortened substring. This makes a  difference  to  the  matching
201           process if the pattern begins with a lookbehind assertion (including \b
202           or \B).
203    
204           If any call to pcre_exec() in a /g or  /G  sequence  matches  an  empty
205           string,  the  next  call  is  done  with  the PCRE_NOTEMPTY_ATSTART and
206           PCRE_ANCHORED flags set in order  to  search  for  another,  non-empty,
207           match  at  the same point. If this second match fails, the start offset
208           is advanced by one character, and the normal  match  is  retried.  This
209           imitates  the way Perl handles such cases when using the /g modifier or
210           the split() function.
211    
212       Other modifiers
213    
214           There are yet more modifiers for controlling the way pcretest operates.
215    
216           The /+ modifier requests that as well as outputting the substring  that
217           matched  the  entire  pattern,  pcretest  should in addition output the
218           remainder of the subject string. This is useful  for  tests  where  the
219           subject contains multiple copies of the same substring.
220    
221           The  /B modifier is a debugging feature. It requests that pcretest out-
222           put a representation of the compiled byte code after compilation.  Nor-
223           mally  this  information contains length and offset values; however, if
224           /Z is also present, this data is replaced by spaces. This is a  special
225           feature for use in the automatic test scripts; it ensures that the same
226           output is generated for different internal link sizes.
227    
228           The /D modifier is a PCRE debugging feature, and is equivalent to  /BI,
229           that is, both the /B and the /I modifiers.
230    
231           The /F modifier causes pcretest to flip the byte order of the fields in
232           the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This
233           facility  is  for testing the feature in PCRE that allows it to execute
234           patterns that were compiled on a host with a different endianness. This
235           feature  is  not  available  when  the POSIX interface to PCRE is being
236           used, that is, when the /P pattern modifier is specified. See also  the
237           section about saving and reloading compiled patterns below.
238    
239           The  /I  modifier  requests  that pcretest output information about the
240           compiled pattern (whether it is anchored, has a fixed first  character,
241           and  so  on). It does this by calling pcre_fullinfo() after compiling a
242           pattern. If the pattern is studied, the results of that are  also  out-
243           put.
244    
245           The  /K modifier requests pcretest to show names from backtracking con-
246           trol verbs that are returned  from  calls  to  pcre_exec().  It  causes
247           pcretest  to create a pcre_extra block if one has not already been cre-
248           ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
249           the mark field within it, every time that pcre_exec() is called. If the
250           variable that the mark field points to is non-NULL for  a  match,  non-
251           match, or partial match, pcretest prints the string to which it points.
252           For a match, this is shown on a line by itself, tagged with "MK:".  For
253           a non-match it is added to the message.
254    
255           The  /L modifier must be followed directly by the name of a locale, for
256           example,
257    
258             /pattern/Lfr_FR
259    
260           For this reason, it must be the last modifier. The given locale is set,
261           pcre_maketables()  is called to build a set of character tables for the
262           locale, and this is then passed to pcre_compile()  when  compiling  the
263           regular  expression.  Without an /L (or /T) modifier, NULL is passed as
264           the tables pointer; that is, /L applies only to the expression on which
265           it appears.
266    
267           The  /M  modifier causes the size of memory block used to hold the com-
268           piled pattern to be output.
269    
270           The /S modifier causes pcre_study() to be called after  the  expression
271           has been compiled, and the results used when the expression is matched.
272    
273           The  /T  modifier  must be followed by a single digit. It causes a spe-
274           cific set of built-in character tables to be passed to  pcre_compile().
275           It is used in the standard PCRE tests to check behaviour with different
276           character tables. The digit specifies the tables as follows:
277    
278             0   the default ASCII tables, as distributed in
279                   pcre_chartables.c.dist
280             1   a set of tables defining ISO 8859 characters
281    
282           In table 1, some characters whose codes are greater than 128 are  iden-
283           tified as letters, digits, spaces, etc.
284    
285       Using the POSIX wrapper API
286    
287           The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
288           rather than its native API. When /P is set, the following modifiers set
289           options for the regcomp() function:
290    
291             /i    REG_ICASE
292             /m    REG_NEWLINE
293             /N    REG_NOSUB
294             /s    REG_DOTALL     )
295             /U    REG_UNGREEDY   ) These options are not part of
296             /W    REG_UCP        )   the POSIX standard
297             /8    REG_UTF8       )
298    
299           The  /+  modifier  works  as  described  above. All other modifiers are
300           ignored.
301    
302    
303    DATA LINES
304    
305           Before each data line is passed to pcre_exec(),  leading  and  trailing
306           whitespace  is  removed,  and it is then scanned for \ escapes. Some of
307           these are pretty esoteric features, intended for checking out  some  of
308           the  more  complicated features of PCRE. If you are just testing "ordi-
309           nary" regular expressions, you probably don't need any  of  these.  The
310           following escapes are recognized:
311    
312             \a         alarm (BEL, \x07)
313             \b         backspace (\x08)
314             \e         escape (\x27)
315             \f         formfeed (\x0c)
316             \n         newline (\x0a)
317             \qdd       set the PCRE_MATCH_LIMIT limit to dd
318                          (any number of digits)
319             \r         carriage return (\x0d)
320             \t         tab (\x09)
321             \v         vertical tab (\x0b)
322             \nnn       octal character (up to 3 octal digits)
323             \xhh       hexadecimal character (up to 2 hex digits)
324             \x{hh...}  hexadecimal character, any number of digits
325                          in UTF-8 mode
326             \A         pass the PCRE_ANCHORED option to pcre_exec()
327                          or pcre_dfa_exec()
328             \B         pass the PCRE_NOTBOL option to pcre_exec()
329                          or pcre_dfa_exec()
330             \Cdd       call pcre_copy_substring() for substring dd
331                          after a successful match (number less than 32)
332             \Cname     call pcre_copy_named_substring() for substring
333                          "name" after a successful match (name termin-
334                          ated by next non alphanumeric character)
335             \C+        show the current captured substrings at callout
336                          time
337             \C-        do not supply a callout function
338             \C!n       return 1 instead of 0 when callout number n is
339                          reached
340             \C!n!m     return 1 instead of 0 when callout number n is
341                          reached for the nth time
342             \C*n       pass the number n (may be negative) as callout
343                          data; this is used as the callout return value
344             \D         use the pcre_dfa_exec() match function
345             \F         only shortest match for pcre_dfa_exec()
346             \Gdd       call pcre_get_substring() for substring dd
347                          after a successful match (number less than 32)
348             \Gname     call pcre_get_named_substring() for substring
349                          "name" after a successful match (name termin-
350                          ated by next non-alphanumeric character)
351             \L         call pcre_get_substringlist() after a
352                          successful match
353             \M         discover the minimum MATCH_LIMIT and
354                          MATCH_LIMIT_RECURSION settings
355             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
356                          or pcre_dfa_exec(); if used twice, pass the
357                          PCRE_NOTEMPTY_ATSTART option
358             \Odd       set the size of the output vector passed to
359                          pcre_exec() to dd (any number of digits)
360             \P         pass the PCRE_PARTIAL_SOFT option to pcre_exec()
361                          or pcre_dfa_exec(); if used twice, pass the
362                          PCRE_PARTIAL_HARD option
363             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
364                          (any number of digits)
365             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
366             \S         output details of memory get/free calls during matching
367             \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
368                          or pcre_dfa_exec()
369             \Z         pass the PCRE_NOTEOL option to pcre_exec()
370                          or pcre_dfa_exec()
371             \?         pass the PCRE_NO_UTF8_CHECK option to
372                          pcre_exec() or pcre_dfa_exec()
373             \>dd       start the match at offset dd (any number of digits);
374                          this sets the startoffset argument for pcre_exec()
375                          or pcre_dfa_exec()
376             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
377                          or pcre_dfa_exec()
378             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
379                          or pcre_dfa_exec()
380             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
381                          or pcre_dfa_exec()
382             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
383                          or pcre_dfa_exec()
384             \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()
385                          or pcre_dfa_exec()
386    
387           The  escapes  that  specify  line ending sequences are literal strings,
388           exactly as shown. No more than one newline setting should be present in
389           any data line.
390    
391           A  backslash  followed by anything else just escapes the anything else.
392           If the very last character is a backslash, it is ignored. This gives  a
393           way  of  passing  an empty line as data, since a real empty line termi-
394           nates the data input.
395    
396           If \M is present, pcretest calls pcre_exec() several times,  with  dif-
397           ferent  values  in  the match_limit and match_limit_recursion fields of
398           the pcre_extra data structure, until it finds the minimum  numbers  for
399           each parameter that allow pcre_exec() to complete. The match_limit num-
400           ber is a measure of the amount of backtracking that  takes  place,  and
401           checking it out can be instructive. For most simple matches, the number
402           is quite small, but for patterns with very large  numbers  of  matching
403           possibilities,  it can become large very quickly with increasing length
404           of subject string. The match_limit_recursion number is a measure of how
405           much  stack  (or,  if  PCRE is compiled with NO_RECURSE, how much heap)
406           memory is needed to complete the match attempt.
407    
408           When \O is used, the value specified may be higher or  lower  than  the
409           size set by the -O command line option (or defaulted to 45); \O applies
410           only to the call of pcre_exec() for the line in which it appears.
411    
412           If the /P modifier was present on the pattern, causing the POSIX  wrap-
413           per  API  to  be  used, the only option-setting sequences that have any
414           effect are \B,  \N,  and  \Z,  causing  REG_NOTBOL,  REG_NOTEMPTY,  and
415           REG_NOTEOL, respectively, to be passed to regexec().
416    
417           The  use of \x{hh...} to represent UTF-8 characters is not dependent on
418           the use of the /8 modifier on the pattern.  It  is  recognized  always.
419           There  may  be  any number of hexadecimal digits inside the braces. The
420           result is from one to six bytes,  encoded  according  to  the  original
421           UTF-8  rules  of  RFC  2279.  This  allows for values in the range 0 to
422           0x7FFFFFFF. Note that not all of those are valid Unicode  code  points,
423           or  indeed  valid  UTF-8 characters according to the later rules in RFC
424           3629.
425    
426    
427    THE ALTERNATIVE MATCHING FUNCTION
428    
429           By  default,  pcretest  uses  the  standard  PCRE  matching   function,
430           pcre_exec() to match each data line. From release 6.0, PCRE supports an
431           alternative matching function, pcre_dfa_test(),  which  operates  in  a
432           different  way,  and has some restrictions. The differences between the
433           two functions are described in the pcrematching documentation.
434    
435           If a data line contains the \D escape sequence, or if the command  line
436           contains  the -dfa option, the alternative matching function is called.
437           This function finds all possible matches at a given point. If, however,
438           the  \F escape sequence is present in the data line, it stops after the
439           first match is found. This is always the shortest possible match.
440    
441    
442    DEFAULT OUTPUT FROM PCRETEST
443    
444           This section describes the output when the  normal  matching  function,
445           pcre_exec(), is being used.
446    
447           When a match succeeds, pcretest outputs the list of captured substrings
448           that pcre_exec() returns, starting with number 0 for  the  string  that
449           matched  the  whole  pattern. Otherwise, it outputs "No match" when the
450           return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
451           tially  matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
452           For any other returns, it outputs the PCRE negative error number.  Here
453           is an example of an interactive pcretest run.
454    
455             $ pcretest
456             PCRE version 7.0 30-Nov-2006
457    
458               re> /^abc(\d+)/
459             data> abc123
460              0: abc123
461              1: 123
462             data> xyz
463             No match
464    
465           Note  that unset capturing substrings that are not followed by one that
466           is set are not returned by pcre_exec(), and are not shown by  pcretest.
467           In  the following example, there are two capturing substrings, but when
468           the first data line is matched, the  second,  unset  substring  is  not
469           shown.  An "internal" unset substring is shown as "<unset>", as for the
470           second data line.
471    
472               re> /(a)|(b)/
473             data> a
474              0: a
475              1: a
476             data> b
477              0: b
478              1: <unset>
479              2: b
480    
481           If the strings contain any non-printing characters, they are output  as
482           \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
483           the pattern. See below for the definition of  non-printing  characters.
484           If  the pattern has the /+ modifier, the output for substring 0 is fol-
485           lowed by the the rest of the subject string, identified  by  "0+"  like
486           this:
487    
488               re> /cat/+
489             data> cataract
490              0: cat
491              0+ aract
492    
493           If  the  pattern  has  the /g or /G modifier, the results of successive
494           matching attempts are output in sequence, like this:
495    
496               re> /\Bi(\w\w)/g
497             data> Mississippi
498              0: iss
499              1: ss
500              0: iss
501              1: ss
502              0: ipp
503              1: pp
504    
505           "No match" is output only if the first match attempt fails.
506    
507           If any of the sequences \C, \G, or \L are present in a data  line  that
508           is  successfully  matched,  the substrings extracted by the convenience
509           functions are output with C, G, or L after the string number instead of
510           a colon. This is in addition to the normal full list. The string length
511           (that is, the return from the extraction function) is given  in  paren-
512           theses after each string for \C and \G.
513    
514           Note that whereas patterns can be continued over several lines (a plain
515           ">" prompt is used for continuations), data lines may not. However new-
516           lines  can  be included in data by means of the \n escape (or \r, \r\n,
517           etc., depending on the newline sequence setting).
518    
519    
520    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
521    
522           When the alternative matching function, pcre_dfa_exec(),  is  used  (by
523           means  of  the \D escape sequence or the -dfa command line option), the
524           output consists of a list of all the matches that start  at  the  first
525           point in the subject where there is at least one match. For example:
526    
527               re> /(tang|tangerine|tan)/
528             data> yellow tangerine\D
529              0: tangerine
530              1: tang
531              2: tan
532    
533           (Using  the  normal  matching function on this data finds only "tang".)
534           The longest matching string is always given first (and numbered  zero).
535           After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
536           lowed by the partially matching substring.
537    
538           If /g is present on the pattern, the search for further matches resumes
539           at the end of the longest match. For example:
540    
541               re> /(tang|tangerine|tan)/g
542             data> yellow tangerine and tangy sultana\D
543              0: tangerine
544              1: tang
545              2: tan
546              0: tang
547              1: tan
548              0: tan
549    
550           Since  the  matching  function  does not support substring capture, the
551           escape sequences that are concerned with captured  substrings  are  not
552           relevant.
553    
554    
555    RESTARTING AFTER A PARTIAL MATCH
556    
557           When the alternative matching function has given the PCRE_ERROR_PARTIAL
558           return, indicating that the subject partially matched the pattern,  you
559           can  restart  the match with additional subject data by means of the \R
560           escape sequence. For example:
561    
562               re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
563             data> 23ja\P\D
564             Partial match: 23ja
565             data> n05\R\D
566              0: n05
567    
568           For further information about partial  matching,  see  the  pcrepartial
569           documentation.
570    
571    
572    CALLOUTS
573    
574           If  the pattern contains any callout requests, pcretest's callout func-
575           tion is called during matching. This works  with  both  matching  func-
576           tions. By default, the called function displays the callout number, the
577           start and current positions in the text at the callout  time,  and  the
578           next pattern item to be tested. For example, the output
579    
580             --->pqrabcdef
581               0    ^  ^     \d
582    
583           indicates  that  callout number 0 occurred for a match attempt starting
584           at the fourth character of the subject string, when the pointer was  at
585           the  seventh  character of the data, and when the next pattern item was
586           \d. Just one circumflex is output if the start  and  current  positions
587           are the same.
588    
589           Callouts numbered 255 are assumed to be automatic callouts, inserted as
590           a result of the /C pattern modifier. In this case, instead  of  showing
591           the  callout  number, the offset in the pattern, preceded by a plus, is
592           output. For example:
593    
594               re> /\d?[A-E]\*/C
595             data> E*
596             --->E*
597              +0 ^      \d?
598              +3 ^      [A-E]
599              +8 ^^     \*
600             +10 ^ ^
601              0: E*
602    
603           The callout function in pcretest returns zero (carry  on  matching)  by
604           default,  but you can use a \C item in a data line (as described above)
605           to change this.
606    
607           Inserting callouts can be helpful when using pcretest to check  compli-
608           cated  regular expressions. For further information about callouts, see
609           the pcrecallout documentation.
610    
611    
612    NON-PRINTING CHARACTERS
613    
614           When pcretest is outputting text in the compiled version of a  pattern,
615           bytes  other  than 32-126 are always treated as non-printing characters
616           are are therefore shown as hex escapes.
617    
618           When pcretest is outputting text that is a matched part  of  a  subject
619           string,  it behaves in the same way, unless a different locale has been
620           set for the  pattern  (using  the  /L  modifier).  In  this  case,  the
621           isprint() function to distinguish printing and non-printing characters.
622    
623    
624    SAVING AND RELOADING COMPILED PATTERNS
625    
626           The  facilities  described  in  this section are not available when the
627           POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
628           ifier is specified.
629    
630           When the POSIX interface is not in use, you can cause pcretest to write
631           a compiled pattern to a file, by following the modifiers with >  and  a
632           file name.  For example:
633    
634             /pattern/im >/some/file
635    
636           See  the pcreprecompile documentation for a discussion about saving and
637           re-using compiled patterns.
638    
639           The data that is written is binary.  The  first  eight  bytes  are  the
640           length  of  the  compiled  pattern  data  followed by the length of the
641           optional study data, each written as four  bytes  in  big-endian  order
642           (most  significant  byte  first). If there is no study data (either the
643           pattern was not studied, or studying did not return any data), the sec-
644           ond  length  is  zero. The lengths are followed by an exact copy of the
645           compiled pattern. If there is additional study data, this follows imme-
646           diately  after  the  compiled pattern. After writing the file, pcretest
647           expects to read a new pattern.
648    
649           A saved pattern can be reloaded into pcretest by specifing < and a file
650           name  instead  of  a pattern. The name of the file must not contain a <
651           character, as otherwise pcretest will interpret the line as  a  pattern
652           delimited by < characters.  For example:
653    
654              re> </some/file
655             Compiled regex loaded from /some/file
656             No study data
657    
658           When  the pattern has been loaded, pcretest proceeds to read data lines
659           in the usual way.
660    
661           You can copy a file written by pcretest to a different host and  reload
662           it  there,  even  if the new host has opposite endianness to the one on
663           which the pattern was compiled. For example, you can compile on an  i86
664           machine and run on a SPARC machine.
665    
666           File  names  for  saving and reloading can be absolute or relative, but
667           note that the shell facility of expanding a file name that starts  with
668           a tilde (~) is not available.
669    
670           The  ability to save and reload files in pcretest is intended for test-
671           ing and experimentation. It is not intended for production use  because
672           only  a  single pattern can be written to a file. Furthermore, there is
673           no facility for supplying  custom  character  tables  for  use  with  a
674           reloaded  pattern.  If  the  original  pattern was compiled with custom
675           tables, an attempt to match a subject string using a  reloaded  pattern
676           is  likely to cause pcretest to crash.  Finally, if you attempt to load
677           a file that is not in the correct format, the result is undefined.
678    
679    
680    SEE ALSO
681    
682           pcre(3), pcreapi(3), pcrecallout(3),  pcrematching(3),  pcrepartial(d),
683           pcrepattern(3), pcreprecompile(3).
684    
685    
686    AUTHOR
687    
688           Philip Hazel
689           University Computing Service
690           Cambridge CB2 3QH, England.
691    
692    
693    REVISION
694    
695           Last updated: 14 June 2010
696           Copyright (c) 1997-2010 University of Cambridge.

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