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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.  
   
 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  
 set. 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 testinput files 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 flag set so that it cannot match an  
 empty string again at the same point. If however, this second match fails, the  
 start offset is advanced by one, and the 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_info() 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             /Y              PCRE_NO_START_OPTIMIZE
172             /<JS>           PCRE_JAVASCRIPT_COMPAT
173             /<cr>           PCRE_NEWLINE_CR
174             /<lf>           PCRE_NEWLINE_LF
175             /<crlf>         PCRE_NEWLINE_CRLF
176             /<anycrlf>      PCRE_NEWLINE_ANYCRLF
177             /<any>          PCRE_NEWLINE_ANY
178             /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
179             /<bsr_unicode>  PCRE_BSR_UNICODE
180    
181           The modifiers that are enclosed in angle brackets are  literal  strings
182           as  shown,  including  the  angle  brackets,  but the letters can be in
183           either case. This example sets multiline matching with CRLF as the line
184           ending sequence:
185    
186             /^abc/m<crlf>
187    
188           As well as turning on the PCRE_UTF8 option, the /8 modifier also causes
189           any non-printing characters in output strings to be printed  using  the
190           \x{hh...}  notation  if they are valid UTF-8 sequences. Full details of
191           the PCRE options are given in the pcreapi documentation.
192    
193       Finding all matches in a string
194    
195           Searching for all possible matches within each subject  string  can  be
196           requested  by  the  /g  or  /G modifier. After finding a match, PCRE is
197           called again to search the remainder of the subject string. The differ-
198           ence between /g and /G is that the former uses the startoffset argument
199           to pcre_exec() to start searching at a  new  point  within  the  entire
200           string  (which  is in effect what Perl does), whereas the latter passes
201           over a shortened substring. This makes a  difference  to  the  matching
202           process if the pattern begins with a lookbehind assertion (including \b
203           or \B).
204    
205           If any call to pcre_exec() in a /g or  /G  sequence  matches  an  empty
206           string,  the  next  call  is  done  with  the PCRE_NOTEMPTY_ATSTART and
207           PCRE_ANCHORED flags set in order  to  search  for  another,  non-empty,
208           match  at  the same point. If this second match fails, the start offset
209           is advanced, and the normal match is retried.  This  imitates  the  way
210           Perl handles such cases when using the /g modifier or the split() func-
211           tion. Normally, the start offset is advanced by one character,  but  if
212           the  newline  convention  recognizes CRLF as a newline, and the current
213           character is CR followed by LF, an advance of two is used.
214    
215       Other modifiers
216    
217           There are yet more modifiers for controlling the way pcretest operates.
218    
219           The /+ modifier requests that as well as outputting the substring  that
220           matched  the  entire  pattern,  pcretest  should in addition output the
221           remainder of the subject string. This is useful  for  tests  where  the
222           subject contains multiple copies of the same substring.
223    
224           The  /B modifier is a debugging feature. It requests that pcretest out-
225           put a representation of the compiled byte code after compilation.  Nor-
226           mally  this  information contains length and offset values; however, if
227           /Z is also present, this data is replaced by spaces. This is a  special
228           feature for use in the automatic test scripts; it ensures that the same
229           output is generated for different internal link sizes.
230    
231           The /D modifier is a PCRE debugging feature, and is equivalent to  /BI,
232           that is, both the /B and the /I modifiers.
233    
234           The /F modifier causes pcretest to flip the byte order of the fields in
235           the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This
236           facility  is  for testing the feature in PCRE that allows it to execute
237           patterns that were compiled on a host with a different endianness. This
238           feature  is  not  available  when  the POSIX interface to PCRE is being
239           used, that is, when the /P pattern modifier is specified. See also  the
240           section about saving and reloading compiled patterns below.
241    
242           The  /I  modifier  requests  that pcretest output information about the
243           compiled pattern (whether it is anchored, has a fixed first  character,
244           and  so  on). It does this by calling pcre_fullinfo() after compiling a
245           pattern. If the pattern is studied, the results of that are  also  out-
246           put.
247    
248           The  /K modifier requests pcretest to show names from backtracking con-
249           trol verbs that are returned  from  calls  to  pcre_exec().  It  causes
250           pcretest  to create a pcre_extra block if one has not already been cre-
251           ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
252           the mark field within it, every time that pcre_exec() is called. If the
253           variable that the mark field points to is non-NULL for  a  match,  non-
254           match, or partial match, pcretest prints the string to which it points.
255           For a match, this is shown on a line by itself, tagged with "MK:".  For
256           a non-match it is added to the message.
257    
258           The  /L modifier must be followed directly by the name of a locale, for
259           example,
260    
261             /pattern/Lfr_FR
262    
263           For this reason, it must be the last modifier. The given locale is set,
264           pcre_maketables()  is called to build a set of character tables for the
265           locale, and this is then passed to pcre_compile()  when  compiling  the
266           regular  expression.  Without an /L (or /T) modifier, NULL is passed as
267           the tables pointer; that is, /L applies only to the expression on which
268           it appears.
269    
270           The  /M  modifier causes the size of memory block used to hold the com-
271           piled pattern to be output.
272    
273           The /S modifier causes pcre_study() to be called after  the  expression
274           has been compiled, and the results used when the expression is matched.
275    
276           The  /T  modifier  must be followed by a single digit. It causes a spe-
277           cific set of built-in character tables to be passed to  pcre_compile().
278           It is used in the standard PCRE tests to check behaviour with different
279           character tables. The digit specifies the tables as follows:
280    
281             0   the default ASCII tables, as distributed in
282                   pcre_chartables.c.dist
283             1   a set of tables defining ISO 8859 characters
284    
285           In table 1, some characters whose codes are greater than 128 are  iden-
286           tified as letters, digits, spaces, etc.
287    
288       Using the POSIX wrapper API
289    
290           The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
291           rather than its native API. When /P is set, the following modifiers set
292           options for the regcomp() function:
293    
294             /i    REG_ICASE
295             /m    REG_NEWLINE
296             /N    REG_NOSUB
297             /s    REG_DOTALL     )
298             /U    REG_UNGREEDY   ) These options are not part of
299             /W    REG_UCP        )   the POSIX standard
300             /8    REG_UTF8       )
301    
302           The  /+  modifier  works  as  described  above. All other modifiers are
303           ignored.
304    
305    
306    DATA LINES
307    
308           Before each data line is passed to pcre_exec(),  leading  and  trailing
309           whitespace  is  removed,  and it is then scanned for \ escapes. Some of
310           these are pretty esoteric features, intended for checking out  some  of
311           the  more  complicated features of PCRE. If you are just testing "ordi-
312           nary" regular expressions, you probably don't need any  of  these.  The
313           following escapes are recognized:
314    
315             \a         alarm (BEL, \x07)
316             \b         backspace (\x08)
317             \e         escape (\x27)
318             \f         formfeed (\x0c)
319             \n         newline (\x0a)
320             \qdd       set the PCRE_MATCH_LIMIT limit to dd
321                          (any number of digits)
322             \r         carriage return (\x0d)
323             \t         tab (\x09)
324             \v         vertical tab (\x0b)
325             \nnn       octal character (up to 3 octal digits)
326                          always a byte unless > 255 in UTF-8 mode
327             \xhh       hexadecimal byte (up to 2 hex digits)
328             \x{hh...}  hexadecimal character, any number of digits
329                          in UTF-8 mode
330             \A         pass the PCRE_ANCHORED option to pcre_exec()
331                          or pcre_dfa_exec()
332             \B         pass the PCRE_NOTBOL option to pcre_exec()
333                          or pcre_dfa_exec()
334             \Cdd       call pcre_copy_substring() for substring dd
335                          after a successful match (number less than 32)
336             \Cname     call pcre_copy_named_substring() for substring
337                          "name" after a successful match (name termin-
338                          ated by next non alphanumeric character)
339             \C+        show the current captured substrings at callout
340                          time
341             \C-        do not supply a callout function
342             \C!n       return 1 instead of 0 when callout number n is
343                          reached
344             \C!n!m     return 1 instead of 0 when callout number n is
345                          reached for the nth time
346             \C*n       pass the number n (may be negative) as callout
347                          data; this is used as the callout return value
348             \D         use the pcre_dfa_exec() match function
349             \F         only shortest match for pcre_dfa_exec()
350             \Gdd       call pcre_get_substring() for substring dd
351                          after a successful match (number less than 32)
352             \Gname     call pcre_get_named_substring() for substring
353                          "name" after a successful match (name termin-
354                          ated by next non-alphanumeric character)
355             \L         call pcre_get_substringlist() after a
356                          successful match
357             \M         discover the minimum MATCH_LIMIT and
358                          MATCH_LIMIT_RECURSION settings
359             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
360                          or pcre_dfa_exec(); if used twice, pass the
361                          PCRE_NOTEMPTY_ATSTART option
362             \Odd       set the size of the output vector passed to
363                          pcre_exec() to dd (any number of digits)
364             \P         pass the PCRE_PARTIAL_SOFT option to pcre_exec()
365                          or pcre_dfa_exec(); if used twice, pass the
366                          PCRE_PARTIAL_HARD option
367             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
368                          (any number of digits)
369             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
370             \S         output details of memory get/free calls during matching
371             \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
372                          or pcre_dfa_exec()
373             \Z         pass the PCRE_NOTEOL option to pcre_exec()
374                          or pcre_dfa_exec()
375             \?         pass the PCRE_NO_UTF8_CHECK option to
376                          pcre_exec() or pcre_dfa_exec()
377             \>dd       start the match at offset dd (optional "-"; then
378                          any number of digits); this sets the startoffset
379                          argument for pcre_exec() or pcre_dfa_exec()
380             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
381                          or pcre_dfa_exec()
382             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
383                          or pcre_dfa_exec()
384             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
385                          or pcre_dfa_exec()
386             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
387                          or pcre_dfa_exec()
388             \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()
389                          or pcre_dfa_exec()
390    
391           Note  that  \xhh  always  specifies  one byte, even in UTF-8 mode; this
392           makes it possible to construct invalid UTF-8 sequences for testing pur-
393           poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
394           UTF-8 mode, generating more than one byte if the value is greater  than
395           127. When not in UTF-8 mode, it generates one byte for values less than
396           256, and causes an error for greater values.
397    
398           The escapes that specify line ending  sequences  are  literal  strings,
399           exactly as shown. No more than one newline setting should be present in
400           any data line.
401    
402           A backslash followed by anything else just escapes the  anything  else.
403           If  the very last character is a backslash, it is ignored. This gives a
404           way of passing an empty line as data, since a real  empty  line  termi-
405           nates the data input.
406    
407           If  \M  is present, pcretest calls pcre_exec() several times, with dif-
408           ferent values in the match_limit and  match_limit_recursion  fields  of
409           the  pcre_extra  data structure, until it finds the minimum numbers for
410           each parameter that allow pcre_exec() to complete. The match_limit num-
411           ber  is  a  measure of the amount of backtracking that takes place, and
412           checking it out can be instructive. For most simple matches, the number
413           is  quite  small,  but for patterns with very large numbers of matching
414           possibilities, it can become large very quickly with increasing  length
415           of subject string. The match_limit_recursion number is a measure of how
416           much stack (or, if PCRE is compiled with  NO_RECURSE,  how  much  heap)
417           memory is needed to complete the match attempt.
418    
419           When  \O  is  used, the value specified may be higher or lower than the
420           size set by the -O command line option (or defaulted to 45); \O applies
421           only to the call of pcre_exec() for the line in which it appears.
422    
423           If  the /P modifier was present on the pattern, causing the POSIX wrap-
424           per API to be used, the only option-setting  sequences  that  have  any
425           effect  are  \B,  \N,  and  \Z,  causing  REG_NOTBOL, REG_NOTEMPTY, and
426           REG_NOTEOL, respectively, to be passed to regexec().
427    
428           The use of \x{hh...} to represent UTF-8 characters is not dependent  on
429           the  use  of  the  /8 modifier on the pattern. It is recognized always.
430           There may be any number of hexadecimal digits inside  the  braces.  The
431           result  is  from  one  to  six bytes, encoded according to the original
432           UTF-8 rules of RFC 2279. This allows for  values  in  the  range  0  to
433           0x7FFFFFFF.  Note  that not all of those are valid Unicode code points,
434           or indeed valid UTF-8 characters according to the later  rules  in  RFC
435           3629.
436    
437    
438    THE ALTERNATIVE MATCHING FUNCTION
439    
440           By   default,  pcretest  uses  the  standard  PCRE  matching  function,
441           pcre_exec() to match each data line. From release 6.0, PCRE supports an
442           alternative  matching  function,  pcre_dfa_test(),  which operates in a
443           different way, and has some restrictions. The differences  between  the
444           two functions are described in the pcrematching documentation.
445    
446           If  a data line contains the \D escape sequence, or if the command line
447           contains the -dfa option, the alternative matching function is  called.
448           This function finds all possible matches at a given point. If, however,
449           the \F escape sequence is present in the data line, it stops after  the
450           first match is found. This is always the shortest possible match.
451    
452    
453    DEFAULT OUTPUT FROM PCRETEST
454    
455           This  section  describes  the output when the normal matching function,
456           pcre_exec(), is being used.
457    
458           When a match succeeds, pcretest outputs the list of captured substrings
459           that  pcre_exec()  returns,  starting with number 0 for the string that
460           matched the whole pattern. Otherwise, it outputs "No  match"  when  the
461           return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
462           tially matching substring when pcre_exec() returns  PCRE_ERROR_PARTIAL.
463           (Note  that  this is the entire substring that was inspected during the
464           partial match; it may include characters before the actual match  start
465           if  a  lookbehind assertion, \K, \b, or \B was involved.) For any other
466           returns, it outputs the PCRE negative error number. Here is an  example
467           of an interactive pcretest run.
468    
469             $ pcretest
470             PCRE version 7.0 30-Nov-2006
471    
472               re> /^abc(\d+)/
473             data> abc123
474              0: abc123
475              1: 123
476             data> xyz
477             No match
478    
479           Note  that unset capturing substrings that are not followed by one that
480           is set are not returned by pcre_exec(), and are not shown by  pcretest.
481           In  the following example, there are two capturing substrings, but when
482           the first data line is matched, the  second,  unset  substring  is  not
483           shown.  An "internal" unset substring is shown as "<unset>", as for the
484           second data line.
485    
486               re> /(a)|(b)/
487             data> a
488              0: a
489              1: a
490             data> b
491              0: b
492              1: <unset>
493              2: b
494    
495           If the strings contain any non-printing characters, they are output  as
496           \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
497           the pattern. See below for the definition of  non-printing  characters.
498           If  the pattern has the /+ modifier, the output for substring 0 is fol-
499           lowed by the the rest of the subject string, identified  by  "0+"  like
500           this:
501    
502               re> /cat/+
503             data> cataract
504              0: cat
505              0+ aract
506    
507           If  the  pattern  has  the /g or /G modifier, the results of successive
508           matching attempts are output in sequence, like this:
509    
510               re> /\Bi(\w\w)/g
511             data> Mississippi
512              0: iss
513              1: ss
514              0: iss
515              1: ss
516              0: ipp
517              1: pp
518    
519           "No match" is output only if the first match attempt fails.
520    
521           If any of the sequences \C, \G, or \L are present in a data  line  that
522           is  successfully  matched,  the substrings extracted by the convenience
523           functions are output with C, G, or L after the string number instead of
524           a colon. This is in addition to the normal full list. The string length
525           (that is, the return from the extraction function) is given  in  paren-
526           theses after each string for \C and \G.
527    
528           Note that whereas patterns can be continued over several lines (a plain
529           ">" prompt is used for continuations), data lines may not. However new-
530           lines  can  be included in data by means of the \n escape (or \r, \r\n,
531           etc., depending on the newline sequence setting).
532    
533    
534    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
535    
536           When the alternative matching function, pcre_dfa_exec(),  is  used  (by
537           means  of  the \D escape sequence or the -dfa command line option), the
538           output consists of a list of all the matches that start  at  the  first
539           point in the subject where there is at least one match. For example:
540    
541               re> /(tang|tangerine|tan)/
542             data> yellow tangerine\D
543              0: tangerine
544              1: tang
545              2: tan
546    
547           (Using  the  normal  matching function on this data finds only "tang".)
548           The longest matching string is always given first (and numbered  zero).
549           After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
550           lowed by the partially matching  substring.  (Note  that  this  is  the
551           entire  substring  that  was inspected during the partial match; it may
552           include characters before the actual match start if a lookbehind asser-
553           tion, \K, \b, or \B was involved.)
554    
555           If /g is present on the pattern, the search for further matches resumes
556           at the end of the longest match. For example:
557    
558               re> /(tang|tangerine|tan)/g
559             data> yellow tangerine and tangy sultana\D
560              0: tangerine
561              1: tang
562              2: tan
563              0: tang
564              1: tan
565              0: tan
566    
567           Since the matching function does not  support  substring  capture,  the
568           escape  sequences  that  are concerned with captured substrings are not
569           relevant.
570    
571    
572    RESTARTING AFTER A PARTIAL MATCH
573    
574           When the alternative matching function has given the PCRE_ERROR_PARTIAL
575           return,  indicating that the subject partially matched the pattern, you
576           can restart the match with additional subject data by means of  the  \R
577           escape sequence. For example:
578    
579               re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
580             data> 23ja\P\D
581             Partial match: 23ja
582             data> n05\R\D
583              0: n05
584    
585           For  further  information  about  partial matching, see the pcrepartial
586           documentation.
587    
588    
589    CALLOUTS
590    
591           If the pattern contains any callout requests, pcretest's callout  func-
592           tion  is  called  during  matching. This works with both matching func-
593           tions. By default, the called function displays the callout number, the
594           start  and  current  positions in the text at the callout time, and the
595           next pattern item to be tested. For example, the output
596    
597             --->pqrabcdef
598               0    ^  ^     \d
599    
600           indicates that callout number 0 occurred for a match  attempt  starting
601           at  the fourth character of the subject string, when the pointer was at
602           the seventh character of the data, and when the next pattern  item  was
603           \d.  Just  one  circumflex is output if the start and current positions
604           are the same.
605    
606           Callouts numbered 255 are assumed to be automatic callouts, inserted as
607           a  result  of the /C pattern modifier. In this case, instead of showing
608           the callout number, the offset in the pattern, preceded by a  plus,  is
609           output. For example:
610    
611               re> /\d?[A-E]\*/C
612             data> E*
613             --->E*
614              +0 ^      \d?
615              +3 ^      [A-E]
616              +8 ^^     \*
617             +10 ^ ^
618              0: E*
619    
620           The  callout  function  in pcretest returns zero (carry on matching) by
621           default, but you can use a \C item in a data line (as described  above)
622           to change this.
623    
624           Inserting  callouts can be helpful when using pcretest to check compli-
625           cated regular expressions. For further information about callouts,  see
626           the pcrecallout documentation.
627    
628    
629    NON-PRINTING CHARACTERS
630    
631           When  pcretest is outputting text in the compiled version of a pattern,
632           bytes other than 32-126 are always treated as  non-printing  characters
633           are are therefore shown as hex escapes.
634    
635           When  pcretest  is  outputting text that is a matched part of a subject
636           string, it behaves in the same way, unless a different locale has  been
637           set  for  the  pattern  (using  the  /L  modifier).  In  this case, the
638           isprint() function to distinguish printing and non-printing characters.
639    
640    
641    SAVING AND RELOADING COMPILED PATTERNS
642    
643           The facilities described in this section are  not  available  when  the
644           POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
645           ifier is specified.
646    
647           When the POSIX interface is not in use, you can cause pcretest to write
648           a  compiled  pattern to a file, by following the modifiers with > and a
649           file name.  For example:
650    
651             /pattern/im >/some/file
652    
653           See the pcreprecompile documentation for a discussion about saving  and
654           re-using compiled patterns.
655    
656           The  data  that  is  written  is  binary. The first eight bytes are the
657           length of the compiled pattern data  followed  by  the  length  of  the
658           optional  study  data,  each  written as four bytes in big-endian order
659           (most significant byte first). If there is no study  data  (either  the
660           pattern was not studied, or studying did not return any data), the sec-
661           ond length is zero. The lengths are followed by an exact  copy  of  the
662           compiled pattern. If there is additional study data, this follows imme-
663           diately after the compiled pattern. After writing  the  file,  pcretest
664           expects to read a new pattern.
665    
666           A saved pattern can be reloaded into pcretest by specifing < and a file
667           name instead of a pattern. The name of the file must not  contain  a  <
668           character,  as  otherwise pcretest will interpret the line as a pattern
669           delimited by < characters.  For example:
670    
671              re> </some/file
672             Compiled regex loaded from /some/file
673             No study data
674    
675           When the pattern has been loaded, pcretest proceeds to read data  lines
676           in the usual way.
677    
678           You  can copy a file written by pcretest to a different host and reload
679           it there, even if the new host has opposite endianness to  the  one  on
680           which  the pattern was compiled. For example, you can compile on an i86
681           machine and run on a SPARC machine.
682    
683           File names for saving and reloading can be absolute  or  relative,  but
684           note  that the shell facility of expanding a file name that starts with
685           a tilde (~) is not available.
686    
687           The ability to save and reload files in pcretest is intended for  test-
688           ing  and experimentation. It is not intended for production use because
689           only a single pattern can be written to a file. Furthermore,  there  is
690           no  facility  for  supplying  custom  character  tables  for use with a
691           reloaded pattern. If the original  pattern  was  compiled  with  custom
692           tables,  an  attempt to match a subject string using a reloaded pattern
693           is likely to cause pcretest to crash.  Finally, if you attempt to  load
694           a file that is not in the correct format, the result is undefined.
695    
696    
697    SEE ALSO
698    
699           pcre(3),  pcreapi(3),  pcrecallout(3), pcrematching(3), pcrepartial(d),
700           pcrepattern(3), pcreprecompile(3).
701    
702    
703    AUTHOR
704    
705           Philip Hazel
706           University Computing Service
707           Cambridge CB2 3QH, England.
708    
709    
710    REVISION
711    
712           Last updated: 21 November 2010
713           Copyright (c) 1997-2010 University of Cambridge.

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