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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, and the normal match is retried.  This  imitates  the  way
209           Perl handles such cases when using the /g modifier or the split() func-
210           tion. Normally, the start offset is advanced by one character,  but  if
211           the  newline  convention  recognizes CRLF as a newline, and the current
212           character is CR followed by LF, an advance of two is used.
213    
214       Other modifiers
215    
216           There are yet more modifiers for controlling the way pcretest operates.
217    
218           The /+ modifier requests that as well as outputting the substring  that
219           matched  the  entire  pattern,  pcretest  should in addition output the
220           remainder of the subject string. This is useful  for  tests  where  the
221           subject contains multiple copies of the same substring.
222    
223           The  /B modifier is a debugging feature. It requests that pcretest out-
224           put a representation of the compiled byte code after compilation.  Nor-
225           mally  this  information contains length and offset values; however, if
226           /Z is also present, this data is replaced by spaces. This is a  special
227           feature for use in the automatic test scripts; it ensures that the same
228           output is generated for different internal link sizes.
229    
230           The /D modifier is a PCRE debugging feature, and is equivalent to  /BI,
231           that is, both the /B and the /I modifiers.
232    
233           The /F modifier causes pcretest to flip the byte order of the fields in
234           the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This
235           facility  is  for testing the feature in PCRE that allows it to execute
236           patterns that were compiled on a host with a different endianness. This
237           feature  is  not  available  when  the POSIX interface to PCRE is being
238           used, that is, when the /P pattern modifier is specified. See also  the
239           section about saving and reloading compiled patterns below.
240    
241           The  /I  modifier  requests  that pcretest output information about the
242           compiled pattern (whether it is anchored, has a fixed first  character,
243           and  so  on). It does this by calling pcre_fullinfo() after compiling a
244           pattern. If the pattern is studied, the results of that are  also  out-
245           put.
246    
247           The  /K modifier requests pcretest to show names from backtracking con-
248           trol verbs that are returned  from  calls  to  pcre_exec().  It  causes
249           pcretest  to create a pcre_extra block if one has not already been cre-
250           ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
251           the mark field within it, every time that pcre_exec() is called. If the
252           variable that the mark field points to is non-NULL for  a  match,  non-
253           match, or partial match, pcretest prints the string to which it points.
254           For a match, this is shown on a line by itself, tagged with "MK:".  For
255           a non-match it is added to the message.
256    
257           The  /L modifier must be followed directly by the name of a locale, for
258           example,
259    
260             /pattern/Lfr_FR
261    
262           For this reason, it must be the last modifier. The given locale is set,
263           pcre_maketables()  is called to build a set of character tables for the
264           locale, and this is then passed to pcre_compile()  when  compiling  the
265           regular  expression.  Without an /L (or /T) modifier, NULL is passed as
266           the tables pointer; that is, /L applies only to the expression on which
267           it appears.
268    
269           The  /M  modifier causes the size of memory block used to hold the com-
270           piled pattern to be output.
271    
272           The /S modifier causes pcre_study() to be called after  the  expression
273           has been compiled, and the results used when the expression is matched.
274    
275           The  /T  modifier  must be followed by a single digit. It causes a spe-
276           cific set of built-in character tables to be passed to  pcre_compile().
277           It is used in the standard PCRE tests to check behaviour with different
278           character tables. The digit specifies the tables as follows:
279    
280             0   the default ASCII tables, as distributed in
281                   pcre_chartables.c.dist
282             1   a set of tables defining ISO 8859 characters
283    
284           In table 1, some characters whose codes are greater than 128 are  iden-
285           tified as letters, digits, spaces, etc.
286    
287       Using the POSIX wrapper API
288    
289           The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
290           rather than its native API. When /P is set, the following modifiers set
291           options for the regcomp() function:
292    
293             /i    REG_ICASE
294             /m    REG_NEWLINE
295             /N    REG_NOSUB
296             /s    REG_DOTALL     )
297             /U    REG_UNGREEDY   ) These options are not part of
298             /W    REG_UCP        )   the POSIX standard
299             /8    REG_UTF8       )
300    
301           The  /+  modifier  works  as  described  above. All other modifiers are
302           ignored.
303    
304    
305    DATA LINES
306    
307           Before each data line is passed to pcre_exec(),  leading  and  trailing
308           whitespace  is  removed,  and it is then scanned for \ escapes. Some of
309           these are pretty esoteric features, intended for checking out  some  of
310           the  more  complicated features of PCRE. If you are just testing "ordi-
311           nary" regular expressions, you probably don't need any  of  these.  The
312           following escapes are recognized:
313    
314             \a         alarm (BEL, \x07)
315             \b         backspace (\x08)
316             \e         escape (\x27)
317             \f         formfeed (\x0c)
318             \n         newline (\x0a)
319             \qdd       set the PCRE_MATCH_LIMIT limit to dd
320                          (any number of digits)
321             \r         carriage return (\x0d)
322             \t         tab (\x09)
323             \v         vertical tab (\x0b)
324             \nnn       octal character (up to 3 octal digits)
325                          always a byte unless > 255 in UTF-8 mode
326             \xhh       hexadecimal byte (up to 2 hex digits)
327             \x{hh...}  hexadecimal character, any number of digits
328                          in UTF-8 mode
329             \A         pass the PCRE_ANCHORED option to pcre_exec()
330                          or pcre_dfa_exec()
331             \B         pass the PCRE_NOTBOL option to pcre_exec()
332                          or pcre_dfa_exec()
333             \Cdd       call pcre_copy_substring() for substring dd
334                          after a successful match (number less than 32)
335             \Cname     call pcre_copy_named_substring() for substring
336                          "name" after a successful match (name termin-
337                          ated by next non alphanumeric character)
338             \C+        show the current captured substrings at callout
339                          time
340             \C-        do not supply a callout function
341             \C!n       return 1 instead of 0 when callout number n is
342                          reached
343             \C!n!m     return 1 instead of 0 when callout number n is
344                          reached for the nth time
345             \C*n       pass the number n (may be negative) as callout
346                          data; this is used as the callout return value
347             \D         use the pcre_dfa_exec() match function
348             \F         only shortest match for pcre_dfa_exec()
349             \Gdd       call pcre_get_substring() for substring dd
350                          after a successful match (number less than 32)
351             \Gname     call pcre_get_named_substring() for substring
352                          "name" after a successful match (name termin-
353                          ated by next non-alphanumeric character)
354             \L         call pcre_get_substringlist() after a
355                          successful match
356             \M         discover the minimum MATCH_LIMIT and
357                          MATCH_LIMIT_RECURSION settings
358             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
359                          or pcre_dfa_exec(); if used twice, pass the
360                          PCRE_NOTEMPTY_ATSTART option
361             \Odd       set the size of the output vector passed to
362                          pcre_exec() to dd (any number of digits)
363             \P         pass the PCRE_PARTIAL_SOFT option to pcre_exec()
364                          or pcre_dfa_exec(); if used twice, pass the
365                          PCRE_PARTIAL_HARD option
366             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
367                          (any number of digits)
368             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
369             \S         output details of memory get/free calls during matching
370             \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
371                          or pcre_dfa_exec()
372             \Z         pass the PCRE_NOTEOL option to pcre_exec()
373                          or pcre_dfa_exec()
374             \?         pass the PCRE_NO_UTF8_CHECK option to
375                          pcre_exec() or pcre_dfa_exec()
376             \>dd       start the match at offset dd (optional "-"; then
377                          any number of digits); this sets the startoffset
378                          argument for pcre_exec() or pcre_dfa_exec()
379             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
380                          or pcre_dfa_exec()
381             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
382                          or pcre_dfa_exec()
383             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
384                          or pcre_dfa_exec()
385             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
386                          or pcre_dfa_exec()
387             \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()
388                          or pcre_dfa_exec()
389    
390           Note  that  \xhh  always  specifies  one byte, even in UTF-8 mode; this
391           makes it possible to construct invalid UTF-8 sequences for testing pur-
392           poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
393           UTF-8 mode, generating more than one byte if the value is greater  than
394           127. When not in UTF-8 mode, it generates one byte for values less than
395           256, and causes an error for greater values.
396    
397           The escapes that specify line ending  sequences  are  literal  strings,
398           exactly as shown. No more than one newline setting should be present in
399           any data line.
400    
401           A backslash followed by anything else just escapes the  anything  else.
402           If  the very last character is a backslash, it is ignored. This gives a
403           way of passing an empty line as data, since a real  empty  line  termi-
404           nates the data input.
405    
406           If  \M  is present, pcretest calls pcre_exec() several times, with dif-
407           ferent values in the match_limit and  match_limit_recursion  fields  of
408           the  pcre_extra  data structure, until it finds the minimum numbers for
409           each parameter that allow pcre_exec() to complete. The match_limit num-
410           ber  is  a  measure of the amount of backtracking that takes place, and
411           checking it out can be instructive. For most simple matches, the number
412           is  quite  small,  but for patterns with very large numbers of matching
413           possibilities, it can become large very quickly with increasing  length
414           of subject string. The match_limit_recursion number is a measure of how
415           much stack (or, if PCRE is compiled with  NO_RECURSE,  how  much  heap)
416           memory is needed to complete the match attempt.
417    
418           When  \O  is  used, the value specified may be higher or lower than the
419           size set by the -O command line option (or defaulted to 45); \O applies
420           only to the call of pcre_exec() for the line in which it appears.
421    
422           If  the /P modifier was present on the pattern, causing the POSIX wrap-
423           per API to be used, the only option-setting  sequences  that  have  any
424           effect  are  \B,  \N,  and  \Z,  causing  REG_NOTBOL, REG_NOTEMPTY, and
425           REG_NOTEOL, respectively, to be passed to regexec().
426    
427           The use of \x{hh...} to represent UTF-8 characters is not dependent  on
428           the  use  of  the  /8 modifier on the pattern. It is recognized always.
429           There may be any number of hexadecimal digits inside  the  braces.  The
430           result  is  from  one  to  six bytes, encoded according to the original
431           UTF-8 rules of RFC 2279. This allows for  values  in  the  range  0  to
432           0x7FFFFFFF.  Note  that not all of those are valid Unicode code points,
433           or indeed valid UTF-8 characters according to the later  rules  in  RFC
434           3629.
435    
436    
437    THE ALTERNATIVE MATCHING FUNCTION
438    
439           By   default,  pcretest  uses  the  standard  PCRE  matching  function,
440           pcre_exec() to match each data line. From release 6.0, PCRE supports an
441           alternative  matching  function,  pcre_dfa_test(),  which operates in a
442           different way, and has some restrictions. The differences  between  the
443           two functions are described in the pcrematching documentation.
444    
445           If  a data line contains the \D escape sequence, or if the command line
446           contains the -dfa option, the alternative matching function is  called.
447           This function finds all possible matches at a given point. If, however,
448           the \F escape sequence is present in the data line, it stops after  the
449           first match is found. This is always the shortest possible match.
450    
451    
452    DEFAULT OUTPUT FROM PCRETEST
453    
454           This  section  describes  the output when the normal matching function,
455           pcre_exec(), is being used.
456    
457           When a match succeeds, pcretest outputs the list of captured substrings
458           that  pcre_exec()  returns,  starting with number 0 for the string that
459           matched the whole pattern. Otherwise, it outputs "No  match"  when  the
460           return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
461           tially matching substring when pcre_exec() returns  PCRE_ERROR_PARTIAL.
462           (Note  that  this is the entire substring that was inspected during the
463           partial match; it may include characters before the actual match  start
464           if  a  lookbehind assertion, \K, \b, or \B was involved.) For any other
465           returns, it outputs the PCRE negative error number. Here is an  example
466           of an interactive pcretest run.
467    
468             $ pcretest
469             PCRE version 7.0 30-Nov-2006
470    
471               re> /^abc(\d+)/
472             data> abc123
473              0: abc123
474              1: 123
475             data> xyz
476             No match
477    
478           Note  that unset capturing substrings that are not followed by one that
479           is set are not returned by pcre_exec(), and are not shown by  pcretest.
480           In  the following example, there are two capturing substrings, but when
481           the first data line is matched, the  second,  unset  substring  is  not
482           shown.  An "internal" unset substring is shown as "<unset>", as for the
483           second data line.
484    
485               re> /(a)|(b)/
486             data> a
487              0: a
488              1: a
489             data> b
490              0: b
491              1: <unset>
492              2: b
493    
494           If the strings contain any non-printing characters, they are output  as
495           \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
496           the pattern. See below for the definition of  non-printing  characters.
497           If  the pattern has the /+ modifier, the output for substring 0 is fol-
498           lowed by the the rest of the subject string, identified  by  "0+"  like
499           this:
500    
501               re> /cat/+
502             data> cataract
503              0: cat
504              0+ aract
505    
506           If  the  pattern  has  the /g or /G modifier, the results of successive
507           matching attempts are output in sequence, like this:
508    
509               re> /\Bi(\w\w)/g
510             data> Mississippi
511              0: iss
512              1: ss
513              0: iss
514              1: ss
515              0: ipp
516              1: pp
517    
518           "No match" is output only if the first match attempt fails.
519    
520           If any of the sequences \C, \G, or \L are present in a data  line  that
521           is  successfully  matched,  the substrings extracted by the convenience
522           functions are output with C, G, or L after the string number instead of
523           a colon. This is in addition to the normal full list. The string length
524           (that is, the return from the extraction function) is given  in  paren-
525           theses after each string for \C and \G.
526    
527           Note that whereas patterns can be continued over several lines (a plain
528           ">" prompt is used for continuations), data lines may not. However new-
529           lines  can  be included in data by means of the \n escape (or \r, \r\n,
530           etc., depending on the newline sequence setting).
531    
532    
533    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
534    
535           When the alternative matching function, pcre_dfa_exec(),  is  used  (by
536           means  of  the \D escape sequence or the -dfa command line option), the
537           output consists of a list of all the matches that start  at  the  first
538           point in the subject where there is at least one match. For example:
539    
540               re> /(tang|tangerine|tan)/
541             data> yellow tangerine\D
542              0: tangerine
543              1: tang
544              2: tan
545    
546           (Using  the  normal  matching function on this data finds only "tang".)
547           The longest matching string is always given first (and numbered  zero).
548           After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
549           lowed by the partially matching  substring.  (Note  that  this  is  the
550           entire  substring  that  was inspected during the partial match; it may
551           include characters before the actual match start if a lookbehind asser-
552           tion, \K, \b, or \B was involved.)
553    
554           If /g is present on the pattern, the search for further matches resumes
555           at the end of the longest match. For example:
556    
557               re> /(tang|tangerine|tan)/g
558             data> yellow tangerine and tangy sultana\D
559              0: tangerine
560              1: tang
561              2: tan
562              0: tang
563              1: tan
564              0: tan
565    
566           Since the matching function does not  support  substring  capture,  the
567           escape  sequences  that  are concerned with captured substrings are not
568           relevant.
569    
570    
571    RESTARTING AFTER A PARTIAL MATCH
572    
573           When the alternative matching function has given the PCRE_ERROR_PARTIAL
574           return,  indicating that the subject partially matched the pattern, you
575           can restart the match with additional subject data by means of  the  \R
576           escape sequence. For example:
577    
578               re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
579             data> 23ja\P\D
580             Partial match: 23ja
581             data> n05\R\D
582              0: n05
583    
584           For  further  information  about  partial matching, see the pcrepartial
585           documentation.
586    
587    
588    CALLOUTS
589    
590           If the pattern contains any callout requests, pcretest's callout  func-
591           tion  is  called  during  matching. This works with both matching func-
592           tions. By default, the called function displays the callout number, the
593           start  and  current  positions in the text at the callout time, and the
594           next pattern item to be tested. For example, the output
595    
596             --->pqrabcdef
597               0    ^  ^     \d
598    
599           indicates that callout number 0 occurred for a match  attempt  starting
600           at  the fourth character of the subject string, when the pointer was at
601           the seventh character of the data, and when the next pattern  item  was
602           \d.  Just  one  circumflex is output if the start and current positions
603           are the same.
604    
605           Callouts numbered 255 are assumed to be automatic callouts, inserted as
606           a  result  of the /C pattern modifier. In this case, instead of showing
607           the callout number, the offset in the pattern, preceded by a  plus,  is
608           output. For example:
609    
610               re> /\d?[A-E]\*/C
611             data> E*
612             --->E*
613              +0 ^      \d?
614              +3 ^      [A-E]
615              +8 ^^     \*
616             +10 ^ ^
617              0: E*
618    
619           The  callout  function  in pcretest returns zero (carry on matching) by
620           default, but you can use a \C item in a data line (as described  above)
621           to change this.
622    
623           Inserting  callouts can be helpful when using pcretest to check compli-
624           cated regular expressions. For further information about callouts,  see
625           the pcrecallout documentation.
626    
627    
628    NON-PRINTING CHARACTERS
629    
630           When  pcretest is outputting text in the compiled version of a pattern,
631           bytes other than 32-126 are always treated as  non-printing  characters
632           are are therefore shown as hex escapes.
633    
634           When  pcretest  is  outputting text that is a matched part of a subject
635           string, it behaves in the same way, unless a different locale has  been
636           set  for  the  pattern  (using  the  /L  modifier).  In  this case, the
637           isprint() function to distinguish printing and non-printing characters.
638    
639    
640    SAVING AND RELOADING COMPILED PATTERNS
641    
642           The facilities described in this section are  not  available  when  the
643           POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
644           ifier is specified.
645    
646           When the POSIX interface is not in use, you can cause pcretest to write
647           a  compiled  pattern to a file, by following the modifiers with > and a
648           file name.  For example:
649    
650             /pattern/im >/some/file
651    
652           See the pcreprecompile documentation for a discussion about saving  and
653           re-using compiled patterns.
654    
655           The  data  that  is  written  is  binary. The first eight bytes are the
656           length of the compiled pattern data  followed  by  the  length  of  the
657           optional  study  data,  each  written as four bytes in big-endian order
658           (most significant byte first). If there is no study  data  (either  the
659           pattern was not studied, or studying did not return any data), the sec-
660           ond length is zero. The lengths are followed by an exact  copy  of  the
661           compiled pattern. If there is additional study data, this follows imme-
662           diately after the compiled pattern. After writing  the  file,  pcretest
663           expects to read a new pattern.
664    
665           A saved pattern can be reloaded into pcretest by specifing < and a file
666           name instead of a pattern. The name of the file must not  contain  a  <
667           character,  as  otherwise pcretest will interpret the line as a pattern
668           delimited by < characters.  For example:
669    
670              re> </some/file
671             Compiled regex loaded from /some/file
672             No study data
673    
674           When the pattern has been loaded, pcretest proceeds to read data  lines
675           in the usual way.
676    
677           You  can copy a file written by pcretest to a different host and reload
678           it there, even if the new host has opposite endianness to  the  one  on
679           which  the pattern was compiled. For example, you can compile on an i86
680           machine and run on a SPARC machine.
681    
682           File names for saving and reloading can be absolute  or  relative,  but
683           note  that the shell facility of expanding a file name that starts with
684           a tilde (~) is not available.
685    
686           The ability to save and reload files in pcretest is intended for  test-
687           ing  and experimentation. It is not intended for production use because
688           only a single pattern can be written to a file. Furthermore,  there  is
689           no  facility  for  supplying  custom  character  tables  for use with a
690           reloaded pattern. If the original  pattern  was  compiled  with  custom
691           tables,  an  attempt to match a subject string using a reloaded pattern
692           is likely to cause pcretest to crash.  Finally, if you attempt to  load
693           a file that is not in the correct format, the result is undefined.
694    
695    
696    SEE ALSO
697    
698           pcre(3),  pcreapi(3),  pcrecallout(3), pcrematching(3), pcrepartial(d),
699           pcrepattern(3), pcreprecompile(3).
700    
701    
702    AUTHOR
703    
704           Philip Hazel
705           University Computing Service
706           Cambridge CB2 3QH, England.
707    
708    
709    REVISION
710    
711           Last updated: 07 November 2010
712           Copyright (c) 1997-2010 University of Cambridge.

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