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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] [input file [output file]]
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. The input  for  pcretest  is  a
18           sequence  of  regular expression patterns and strings to be matched, as
19           described below. The output shows the result of each match. Options  on
20           the command line and the patterns control PCRE options and exactly what
21           is output.
22    
23    
24    COMMAND LINE OPTIONS
25    
26           -b        Behave as if each pattern has the /B (show byte  code)  modi-
27                     fier; the internal form is output after compilation.
28    
29           -C        Output the version number of the PCRE library, and all avail-
30                     able  information  about  the  optional  features  that   are
31                     included, and then exit.
32    
33           -d        Behave  as  if  each pattern has the /D (debug) modifier; the
34                     internal form and information about the compiled  pattern  is
35                     output after compilation; -d is equivalent to -b -i.
36    
37           -dfa      Behave  as if each data line contains the \D escape sequence;
38                     this    causes    the    alternative    matching    function,
39                     pcre_dfa_exec(),   to   be   used  instead  of  the  standard
40                     pcre_exec() function (more detail is given below).
41    
42           -help     Output a brief summary these options and then exit.
43    
44           -i        Behave as if each pattern has the  /I  modifier;  information
45                     about the compiled pattern is given after compilation.
46    
47           -M        Behave  as if each data line contains the \M escape sequence;
48                     this causes PCRE to  discover  the  minimum  MATCH_LIMIT  and
49                     MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
50                     edly with different limits.
51    
52           -m        Output the size of each compiled pattern after  it  has  been
53                     compiled.  This  is  equivalent  to adding /M to each regular
54                     expression.
55    
56           -o osize  Set the number of elements in the output vector that is  used
57                     when  calling pcre_exec() or pcre_dfa_exec() to be osize. The
58                     default value is 45, which is enough for 14 capturing  subex-
59                     pressions   for  pcre_exec()  or  22  different  matches  for
60                     pcre_dfa_exec(). The vector size can be changed for  individ-
61                     ual  matching  calls  by  including  \O in the data line (see
62                     below).
63    
64           -p        Behave as if each pattern has  the  /P  modifier;  the  POSIX
65                     wrapper  API  is used to call PCRE. None of the other options
66                     has any effect when -p is set.
67    
68           -q        Do not output the version number of pcretest at the start  of
69                     execution.
70    
71           -S size   On  Unix-like  systems, set the size of the run-time stack to
72                     size megabytes.
73    
74           -s or -s+ Behave as if each pattern  has  the  /S  modifier;  in  other
75                     words,  force each pattern to be studied. If -s+ is used, the
76                     PCRE_STUDY_JIT_COMPILE flag is passed to pcre_study(),  caus-
77                     ing  just-in-time  optimization  to be set up if it is avail-
78                     able. If the  /I  or  /D  option  is  present  on  a  pattern
79                     (requesting  output  about the compiled pattern), information
80                     about the result of studying is not included when studying is
81                     caused  only  by  -s  and neither -i nor -d is present on the
82                     command line. This behaviour means that the output from tests
83                     that  are run with and without -s should be identical, except
84                     when options that output information about the actual running
85                     of  a  match are set. The -M, -t, and -tm options, which give
86                     information about resources used, are likely to produce  dif-
87                     ferent  output with and without -s. Output may also differ if
88                     the /C option is present on an individual pattern. This  uses
89                     callouts  to  trace the the matching process, and this may be
90                     different between studied and non-studied  patterns.  If  the
91                     pattern contains (*MARK) items there may also be differences,
92                     for the same reason. The -s command line option can be  over-
93                     ridden  for  specific  patterns  that should never be studied
94                     (see the /S pattern modifier below).
95    
96           -t        Run each compile, study, and match many times with  a  timer,
97                     and  output resulting time per compile or match (in millisec-
98                     onds). Do not set -m with -t, because you will then  get  the
99                     size  output  a  zillion  times,  and the timing will be dis-
100                     torted. You can control the number  of  iterations  that  are
101                     used  for timing by following -t with a number (as a separate
102                     item on the command line). For example, "-t 1000" would iter-
103                     ate 1000 times. The default is to iterate 500000 times.
104    
105           -tm       This is like -t except that it times only the matching phase,
106                     not the compile or study phases.
107    
108    
109    DESCRIPTION
110    
111           If pcretest is given two filename arguments, it reads  from  the  first
112           and writes to the second. If it is given only one filename argument, it
113           reads from that file and writes to stdout.  Otherwise,  it  reads  from
114           stdin  and  writes to stdout, and prompts for each line of input, using
115           "re>" to prompt for regular expressions, and "data>" to prompt for data
116           lines.
117    
118           When  pcretest  is  built,  a  configuration option can specify that it
119           should be linked with the libreadline library. When this  is  done,  if
120           the input is from a terminal, it is read using the readline() function.
121           This provides line-editing and history facilities. The output from  the
122           -help option states whether or not readline() will be used.
123    
124           The program handles any number of sets of input on a single input file.
125           Each set starts with a regular expression, and continues with any  num-
126           ber of data lines to be matched against the pattern.
127    
128           Each  data line is matched separately and independently. If you want to
129           do multi-line matches, you have to use the \n escape sequence (or \r or
130           \r\n, etc., depending on the newline setting) in a single line of input
131           to encode the newline sequences. There is no limit  on  the  length  of
132           data  lines;  the  input  buffer is automatically extended if it is too
133           small.
134    
135           An empty line signals the end of the data lines, at which point  a  new
136           regular  expression is read. The regular expressions are given enclosed
137           in any non-alphanumeric delimiters other than backslash, for example:
138    
139             /(a|bc)x+yz/
140    
141           White space before the initial delimiter is ignored. A regular  expres-
142           sion  may be continued over several input lines, in which case the new-
143           line characters are included within it. It is possible to  include  the
144           delimiter within the pattern by escaping it, for example
145    
146             /abc\/def/
147    
148           If  you  do  so, the escape and the delimiter form part of the pattern,
149           but since delimiters are always non-alphanumeric, this does not  affect
150           its  interpretation.   If the terminating delimiter is immediately fol-
151           lowed by a backslash, for example,
152    
153             /abc/\
154    
155           then a backslash is added to the end of the pattern. This  is  done  to
156           provide  a  way of testing the error condition that arises if a pattern
157           finishes with a backslash, because
158    
159             /abc\/
160    
161           is interpreted as the first line of a pattern that starts with  "abc/",
162           causing pcretest to read the next line as a continuation of the regular
163           expression.
164    
165    
166    PATTERN MODIFIERS
167    
168           A pattern may be followed by any number of modifiers, which are  mostly
169           single  characters.  Following  Perl usage, these are referred to below
170           as, for example, "the /i modifier", even though the  delimiter  of  the
171           pattern  need  not always be a slash, and no slash is used when writing
172           modifiers. White space may appear between the final  pattern  delimiter
173           and the first modifier, and between the modifiers themselves.
174    
175           The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
176           PCRE_DOTALL, or PCRE_EXTENDED  options,  respectively,  when  pcre_com-
177           pile()  is  called. These four modifier letters have the same effect as
178           they do in Perl. For example:
179    
180             /caseless/i
181    
182           The following table shows additional modifiers for  setting  PCRE  com-
183           pile-time options that do not correspond to anything in Perl:
184    
185             /8              PCRE_UTF8
186             /?              PCRE_NO_UTF8_CHECK
187             /A              PCRE_ANCHORED
188             /C              PCRE_AUTO_CALLOUT
189             /E              PCRE_DOLLAR_ENDONLY
190             /f              PCRE_FIRSTLINE
191             /J              PCRE_DUPNAMES
192             /N              PCRE_NO_AUTO_CAPTURE
193             /U              PCRE_UNGREEDY
194             /W              PCRE_UCP
195             /X              PCRE_EXTRA
196             /Y              PCRE_NO_START_OPTIMIZE
197             /<JS>           PCRE_JAVASCRIPT_COMPAT
198             /<cr>           PCRE_NEWLINE_CR
199             /<lf>           PCRE_NEWLINE_LF
200             /<crlf>         PCRE_NEWLINE_CRLF
201             /<anycrlf>      PCRE_NEWLINE_ANYCRLF
202             /<any>          PCRE_NEWLINE_ANY
203             /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
204             /<bsr_unicode>  PCRE_BSR_UNICODE
205    
206           The  modifiers  that are enclosed in angle brackets are literal strings
207           as shown, including the angle brackets, but the letters within  can  be
208           in  either case.  This example sets multiline matching with CRLF as the
209           line ending sequence:
210    
211             /^abc/m<CRLF>
212    
213           As well as turning on the PCRE_UTF8 option, the /8 modifier also causes
214           any  non-printing  characters in output strings to be printed using the
215           \x{hh...} notation if they are valid UTF-8 sequences. Full  details  of
216           the PCRE options are given in the pcreapi documentation.
217    
218       Finding all matches in a string
219    
220           Searching  for  all  possible matches within each subject string can be
221           requested by the /g or /G modifier. After  finding  a  match,  PCRE  is
222           called again to search the remainder of the subject string. The differ-
223           ence between /g and /G is that the former uses the startoffset argument
224           to  pcre_exec()  to  start  searching  at a new point within the entire
225           string (which is in effect what Perl does), whereas the  latter  passes
226           over  a  shortened  substring.  This makes a difference to the matching
227           process if the pattern begins with a lookbehind assertion (including \b
228           or \B).
229    
230           If  any  call  to  pcre_exec()  in a /g or /G sequence matches an empty
231           string, the next  call  is  done  with  the  PCRE_NOTEMPTY_ATSTART  and
232           PCRE_ANCHORED  flags  set  in  order  to search for another, non-empty,
233           match at the same point. If this second match fails, the  start  offset
234           is  advanced,  and  the  normal match is retried. This imitates the way
235           Perl handles such cases when using the /g modifier or the split() func-
236           tion.  Normally,  the start offset is advanced by one character, but if
237           the newline convention recognizes CRLF as a newline,  and  the  current
238           character is CR followed by LF, an advance of two is used.
239    
240       Other modifiers
241    
242           There are yet more modifiers for controlling the way pcretest operates.
243    
244           The  /+ modifier requests that as well as outputting the substring that
245           matched the entire pattern, pcretest  should  in  addition  output  the
246           remainder  of  the  subject  string. This is useful for tests where the
247           subject contains multiple copies of the same substring. If the +  modi-
248           fier  appears  twice, the same action is taken for captured substrings.
249           In each case the remainder is output on the following line with a  plus
250           character  following  the  capture number. Note that this modifier must
251           not immediately follow the /S modifier because /S+ has another meaning.
252    
253           The /= modifier requests that the  values  of  all  potential  captured
254           parentheses  be  output  after a match by pcre_exec(). By default, only
255           those up to the highest one actually used in the match are output (cor-
256           responding  to the return code from pcre_exec()). Values in the offsets
257           vector corresponding to higher numbers should be set to -1,  and  these
258           are  output  as  "<unset>".  This modifier gives a way of checking that
259           this is happening.
260    
261           The /B modifier is a debugging feature. It requests that pcretest  out-
262           put  a representation of the compiled byte code after compilation. Nor-
263           mally this information contains length and offset values;  however,  if
264           /Z  is also present, this data is replaced by spaces. This is a special
265           feature for use in the automatic test scripts; it ensures that the same
266           output is generated for different internal link sizes.
267    
268           The  /D modifier is a PCRE debugging feature, and is equivalent to /BI,
269           that is, both the /B and the /I modifiers.
270    
271           The /F modifier causes pcretest to flip the byte order of the fields in
272           the  compiled  pattern  that  contain  2-byte  and 4-byte numbers. This
273           facility is for testing the feature in PCRE that allows it  to  execute
274           patterns that were compiled on a host with a different endianness. This
275           feature is not available when the POSIX  interface  to  PCRE  is  being
276           used,  that is, when the /P pattern modifier is specified. See also the
277           section about saving and reloading compiled patterns below.
278    
279           The /I modifier requests that pcretest  output  information  about  the
280           compiled  pattern (whether it is anchored, has a fixed first character,
281           and so on). It does this by calling pcre_fullinfo() after  compiling  a
282           pattern.  If  the pattern is studied, the results of that are also out-
283           put.
284    
285           The /K modifier requests pcretest to show names from backtracking  con-
286           trol  verbs  that  are  returned  from  calls to pcre_exec(). It causes
287           pcretest to create a pcre_extra block if one has not already been  cre-
288           ated by a call to pcre_study(), and to set the PCRE_EXTRA_MARK flag and
289           the mark field within it, every time that pcre_exec() is called. If the
290           variable  that  the  mark field points to is non-NULL for a match, non-
291           match, or partial match, pcretest prints the string to which it points.
292           For a match, this is shown on a line by itself, tagged with "MK:".  For
293           a non-match it is added to the message.
294    
295           The /L modifier must be followed directly by the name of a locale,  for
296           example,
297    
298             /pattern/Lfr_FR
299    
300           For this reason, it must be the last modifier. The given locale is set,
301           pcre_maketables() is called to build a set of character tables for  the
302           locale,  and  this  is then passed to pcre_compile() when compiling the
303           regular expression. Without an /L (or /T) modifier, NULL is  passed  as
304           the tables pointer; that is, /L applies only to the expression on which
305           it appears.
306    
307           The /M modifier causes the size of memory block used to hold  the  com-
308           piled  pattern to be output. This does not include the size of the pcre
309           block; it is just the actual compiled data. If the pattern is  success-
310           fully  studied  with the PCRE_STUDY_JIT_COMPILE option, the size of the
311           JIT compiled code is also output.
312    
313           If the /S modifier appears once, it causes pcre_study()  to  be  called
314           after  the  expression has been compiled, and the results used when the
315           expression is matched. If /S appears  twice,  it  suppresses  studying,
316           even if it was requested externally by the -s command line option. This
317           makes it possible to specify that certain patterns are always  studied,
318           and others are never studied, independently of -s. This feature is used
319           in the test files in a few cases where the output is different when the
320           pattern is studied.
321    
322           If  the  /S modifier is immediately followed by a + character, the call
323           to  pcre_study()  is  made  with  the  PCRE_STUDY_JIT_COMPILE   option,
324           requesting  just-in-time  optimization support if it is available. Note
325           that there is also a /+ modifier; it  must  not  be  given  immediately
326           after  /S  because this will be misinterpreted. If JIT studying is suc-
327           cessful, it will automatically be used when pcre_exec() is run,  except
328           when  incompatible  run-time  options  are specified. These include the
329           partial matching options; a complete list is given in the pcrejit docu-
330           mentation.  See  also the \J escape sequence below for a way of setting
331           the size of the JIT stack.
332    
333           The /T modifier must be followed by a single digit. It  causes  a  spe-
334           cific  set of built-in character tables to be passed to pcre_compile().
335           It is used in the standard PCRE tests to check behaviour with different
336           character tables. The digit specifies the tables as follows:
337    
338             0   the default ASCII tables, as distributed in
339                   pcre_chartables.c.dist
340             1   a set of tables defining ISO 8859 characters
341    
342           In  table 1, some characters whose codes are greater than 128 are iden-
343           tified as letters, digits, spaces, etc.
344    
345       Using the POSIX wrapper API
346    
347           The /P modifier causes pcretest to call PCRE via the POSIX wrapper  API
348           rather than its native API. When /P is set, the following modifiers set
349           options for the regcomp() function:
350    
351             /i    REG_ICASE
352             /m    REG_NEWLINE
353             /N    REG_NOSUB
354             /s    REG_DOTALL     )
355             /U    REG_UNGREEDY   ) These options are not part of
356             /W    REG_UCP        )   the POSIX standard
357             /8    REG_UTF8       )
358    
359           The /+ modifier works as  described  above.  All  other  modifiers  are
360           ignored.
361    
362    
363    DATA LINES
364    
365           Before  each  data  line is passed to pcre_exec(), leading and trailing
366           white space is removed, and it is then scanned for \ escapes.  Some  of
367           these  are  pretty esoteric features, intended for checking out some of
368           the more complicated features of PCRE. If you are just  testing  "ordi-
369           nary"  regular  expressions,  you probably don't need any of these. The
370           following escapes are recognized:
371    
372             \a         alarm (BEL, \x07)
373             \b         backspace (\x08)
374             \e         escape (\x27)
375             \f         form feed (\x0c)
376             \n         newline (\x0a)
377             \qdd       set the PCRE_MATCH_LIMIT limit to dd
378                          (any number of digits)
379             \r         carriage return (\x0d)
380             \t         tab (\x09)
381             \v         vertical tab (\x0b)
382             \nnn       octal character (up to 3 octal digits)
383                          always a byte unless > 255 in UTF-8 mode
384             \xhh       hexadecimal byte (up to 2 hex digits)
385             \x{hh...}  hexadecimal character, any number of digits
386                          in UTF-8 mode
387             \A         pass the PCRE_ANCHORED option to pcre_exec()
388                          or pcre_dfa_exec()
389             \B         pass the PCRE_NOTBOL option to pcre_exec()
390                          or pcre_dfa_exec()
391             \Cdd       call pcre_copy_substring() for substring dd
392                          after a successful match (number less than 32)
393             \Cname     call pcre_copy_named_substring() for substring
394                          "name" after a successful match (name termin-
395                          ated by next non alphanumeric character)
396             \C+        show the current captured substrings at callout
397                          time
398             \C-        do not supply a callout function
399             \C!n       return 1 instead of 0 when callout number n is
400                          reached
401             \C!n!m     return 1 instead of 0 when callout number n is
402                          reached for the nth time
403             \C*n       pass the number n (may be negative) as callout
404                          data; this is used as the callout return value
405             \D         use the pcre_dfa_exec() match function
406             \F         only shortest match for pcre_dfa_exec()
407             \Gdd       call pcre_get_substring() for substring dd
408                          after a successful match (number less than 32)
409             \Gname     call pcre_get_named_substring() for substring
410                          "name" after a successful match (name termin-
411                          ated by next non-alphanumeric character)
412             \Jdd       set up a JIT stack of dd kilobytes maximum (any
413                          number of digits)
414             \L         call pcre_get_substringlist() after a
415                          successful match
416             \M         discover the minimum MATCH_LIMIT and
417                          MATCH_LIMIT_RECURSION settings
418             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
419                          or pcre_dfa_exec(); if used twice, pass the
420                          PCRE_NOTEMPTY_ATSTART option
421             \Odd       set the size of the output vector passed to
422                          pcre_exec() to dd (any number of digits)
423             \P         pass the PCRE_PARTIAL_SOFT option to pcre_exec()
424                          or pcre_dfa_exec(); if used twice, pass the
425                          PCRE_PARTIAL_HARD option
426             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
427                          (any number of digits)
428             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
429             \S         output details of memory get/free calls during matching
430             \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre_exec()
431                          or pcre_dfa_exec()
432             \Z         pass the PCRE_NOTEOL option to pcre_exec()
433                          or pcre_dfa_exec()
434             \?         pass the PCRE_NO_UTF8_CHECK option to
435                          pcre_exec() or pcre_dfa_exec()
436             \>dd       start the match at offset dd (optional "-"; then
437                          any number of digits); this sets the startoffset
438                          argument for pcre_exec() or pcre_dfa_exec()
439             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
440                          or pcre_dfa_exec()
441             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
442                          or pcre_dfa_exec()
443             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
444                          or pcre_dfa_exec()
445             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
446                          or pcre_dfa_exec()
447             \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()
448                          or pcre_dfa_exec()
449    
450           Note that \xhh always specifies one byte,  even  in  UTF-8  mode;  this
451           makes it possible to construct invalid UTF-8 sequences for testing pur-
452           poses. On the other hand, \x{hh} is interpreted as a UTF-8 character in
453           UTF-8  mode, generating more than one byte if the value is greater than
454           127. When not in UTF-8 mode, it generates one byte for values less than
455           256, and causes an error for greater values.
456    
457           The  escapes  that  specify  line ending sequences are literal strings,
458           exactly as shown. No more than one newline setting should be present in
459           any data line.
460    
461           A  backslash  followed by anything else just escapes the anything else.
462           If the very last character is a backslash, it is ignored. This gives  a
463           way  of  passing  an empty line as data, since a real empty line termi-
464           nates the data input.
465    
466           The \J escape provides a way of setting the maximum stack size that  is
467           used  by the just-in-time optimization code. It is ignored if JIT opti-
468           mization is not being used. Providing a stack that is larger  than  the
469           default 32K is necessary only for very complicated patterns.
470    
471           If  \M  is present, pcretest calls pcre_exec() several times, with dif-
472           ferent values in the match_limit and  match_limit_recursion  fields  of
473           the  pcre_extra  data structure, until it finds the minimum numbers for
474           each parameter  that  allow  pcre_exec()  to  complete  without  error.
475           Because  this  is testing a specific feature of the normal interpretive
476           pcre_exec() execution, the use of any JIT optimization that might  have
477           been set up by the /S+ qualifier of -s+ option is disabled.
478    
479           The  match_limit number is a measure of the amount of backtracking that
480           takes place, and checking it out can be instructive.  For  most  simple
481           matches,  the  number  is quite small, but for patterns with very large
482           numbers of matching possibilities, it can  become  large  very  quickly
483           with  increasing  length  of  subject string. The match_limit_recursion
484           number is a measure of how much stack (or, if  PCRE  is  compiled  with
485           NO_RECURSE,  how  much  heap)  memory  is  needed to complete the match
486           attempt.
487    
488           When \O is used, the value specified may be higher or  lower  than  the
489           size set by the -O command line option (or defaulted to 45); \O applies
490           only to the call of pcre_exec() for the line in which it appears.
491    
492           If the /P modifier was present on the pattern, causing the POSIX  wrap-
493           per  API  to  be  used, the only option-setting sequences that have any
494           effect are \B,  \N,  and  \Z,  causing  REG_NOTBOL,  REG_NOTEMPTY,  and
495           REG_NOTEOL, respectively, to be passed to regexec().
496    
497           The  use of \x{hh...} to represent UTF-8 characters is not dependent on
498           the use of the /8 modifier on the pattern.  It  is  recognized  always.
499           There  may  be  any number of hexadecimal digits inside the braces. The
500           result is from one to six bytes,  encoded  according  to  the  original
501           UTF-8  rules  of  RFC  2279.  This  allows for values in the range 0 to
502           0x7FFFFFFF. Note that not all of those are valid Unicode  code  points,
503           or  indeed  valid  UTF-8 characters according to the later rules in RFC
504           3629.
505    
506    
507    THE ALTERNATIVE MATCHING FUNCTION
508    
509           By  default,  pcretest  uses  the  standard  PCRE  matching   function,
510           pcre_exec() to match each data line. From release 6.0, PCRE supports an
511           alternative matching function, pcre_dfa_test(),  which  operates  in  a
512           different  way,  and has some restrictions. The differences between the
513           two functions are described in the pcrematching documentation.
514    
515           If a data line contains the \D escape sequence, or if the command  line
516           contains  the -dfa option, the alternative matching function is called.
517           This function finds all possible matches at a given point. If, however,
518           the  \F escape sequence is present in the data line, it stops after the
519           first match is found. This is always the shortest possible match.
520    
521    
522    DEFAULT OUTPUT FROM PCRETEST
523    
524           This section describes the output when the  normal  matching  function,
525           pcre_exec(), is being used.
526    
527           When a match succeeds, pcretest outputs the list of captured substrings
528           that pcre_exec() returns, starting with number 0 for  the  string  that
529           matched  the  whole  pattern. Otherwise, it outputs "No match" when the
530           return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the par-
531           tially  matching substring when pcre_exec() returns PCRE_ERROR_PARTIAL.
532           (Note that this is the entire substring that was inspected  during  the
533           partial  match; it may include characters before the actual match start
534           if a lookbehind assertion, \K, \b, or \B was involved.) For  any  other
535           return,  pcretest  outputs  the  PCRE negative error number and a short
536           descriptive phrase. If the error is a failed UTF-8  string  check,  the
537           byte  offset  of the start of the failing character and the reason code
538           are also output, provided that the size of  the  output  vector  is  at
539           least two. Here is an example of an interactive pcretest run.
540    
541             $ pcretest
542             PCRE version 8.13 2011-04-30
543    
544               re> /^abc(\d+)/
545             data> abc123
546              0: abc123
547              1: 123
548             data> xyz
549             No match
550    
551           Unset capturing substrings that are not followed by one that is set are
552           not returned by pcre_exec(), and are not shown by pcretest. In the fol-
553           lowing  example, there are two capturing substrings, but when the first
554           data line is matched, the second, unset  substring  is  not  shown.  An
555           "internal"  unset  substring  is  shown as "<unset>", as for the second
556           data line.
557    
558               re> /(a)|(b)/
559             data> a
560              0: a
561              1: a
562             data> b
563              0: b
564              1: <unset>
565              2: b
566    
567           If the strings contain any non-printing characters, they are output  as
568           \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
569           the pattern. See below for the definition of  non-printing  characters.
570           If  the pattern has the /+ modifier, the output for substring 0 is fol-
571           lowed by the the rest of the subject string, identified  by  "0+"  like
572           this:
573    
574               re> /cat/+
575             data> cataract
576              0: cat
577              0+ aract
578    
579           If  the  pattern  has  the /g or /G modifier, the results of successive
580           matching attempts are output in sequence, like this:
581    
582               re> /\Bi(\w\w)/g
583             data> Mississippi
584              0: iss
585              1: ss
586              0: iss
587              1: ss
588              0: ipp
589              1: pp
590    
591           "No match" is output only if the first match attempt fails. Here is  an
592           example  of a failure message (the offset 4 that is specified by \>4 is
593           past the end of the subject string):
594    
595               re> /xyz/
596             data> xyz\>4
597             Error -24 (bad offset value)
598    
599           If any of the sequences \C, \G, or \L are present in a data  line  that
600           is  successfully  matched,  the substrings extracted by the convenience
601           functions are output with C, G, or L after the string number instead of
602           a colon. This is in addition to the normal full list. The string length
603           (that is, the return from the extraction function) is given  in  paren-
604           theses after each string for \C and \G.
605    
606           Note that whereas patterns can be continued over several lines (a plain
607           ">" prompt is used for continuations), data lines may not. However new-
608           lines  can  be included in data by means of the \n escape (or \r, \r\n,
609           etc., depending on the newline sequence setting).
610    
611    
612    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
613    
614           When the alternative matching function, pcre_dfa_exec(),  is  used  (by
615           means  of  the \D escape sequence or the -dfa command line option), the
616           output consists of a list of all the matches that start  at  the  first
617           point in the subject where there is at least one match. For example:
618    
619               re> /(tang|tangerine|tan)/
620             data> yellow tangerine\D
621              0: tangerine
622              1: tang
623              2: tan
624    
625           (Using  the  normal  matching function on this data finds only "tang".)
626           The longest matching string is always given first (and numbered  zero).
627           After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
628           lowed by the partially matching  substring.  (Note  that  this  is  the
629           entire  substring  that  was inspected during the partial match; it may
630           include characters before the actual match start if a lookbehind asser-
631           tion, \K, \b, or \B was involved.)
632    
633           If /g is present on the pattern, the search for further matches resumes
634           at the end of the longest match. For example:
635    
636               re> /(tang|tangerine|tan)/g
637             data> yellow tangerine and tangy sultana\D
638              0: tangerine
639              1: tang
640              2: tan
641              0: tang
642              1: tan
643              0: tan
644    
645           Since the matching function does not  support  substring  capture,  the
646           escape  sequences  that  are concerned with captured substrings are not
647           relevant.
648    
649    
650    RESTARTING AFTER A PARTIAL MATCH
651    
652           When the alternative matching function has given the PCRE_ERROR_PARTIAL
653           return,  indicating that the subject partially matched the pattern, you
654           can restart the match with additional subject data by means of  the  \R
655           escape sequence. For example:
656    
657               re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
658             data> 23ja\P\D
659             Partial match: 23ja
660             data> n05\R\D
661              0: n05
662    
663           For  further  information  about  partial matching, see the pcrepartial
664           documentation.
665    
666    
667    CALLOUTS
668    
669           If the pattern contains any callout requests, pcretest's callout  func-
670           tion  is  called  during  matching. This works with both matching func-
671           tions. By default, the called function displays the callout number, the
672           start  and  current  positions in the text at the callout time, and the
673           next pattern item to be tested. For example, the output
674    
675             --->pqrabcdef
676               0    ^  ^     \d
677    
678           indicates that callout number 0 occurred for a match  attempt  starting
679           at  the fourth character of the subject string, when the pointer was at
680           the seventh character of the data, and when the next pattern  item  was
681           \d.  Just  one  circumflex is output if the start and current positions
682           are the same.
683    
684           Callouts numbered 255 are assumed to be automatic callouts, inserted as
685           a  result  of the /C pattern modifier. In this case, instead of showing
686           the callout number, the offset in the pattern, preceded by a  plus,  is
687           output. For example:
688    
689               re> /\d?[A-E]\*/C
690             data> E*
691             --->E*
692              +0 ^      \d?
693              +3 ^      [A-E]
694              +8 ^^     \*
695             +10 ^ ^
696              0: E*
697    
698           If a pattern contains (*MARK) items, an additional line is output when-
699           ever a change of latest mark is passed to  the  callout  function.  For
700           example:
701    
702               re> /a(*MARK:X)bc/C
703             data> abc
704             --->abc
705              +0 ^       a
706              +1 ^^      (*MARK:X)
707             +10 ^^      b
708             Latest Mark: X
709             +11 ^ ^     c
710             +12 ^  ^
711              0: abc
712    
713           The  mark  changes between matching "a" and "b", but stays the same for
714           the rest of the match, so nothing more is output. If, as  a  result  of
715           backtracking,  the  mark  reverts to being unset, the text "<unset>" is
716           output.
717    
718           The callout function in pcretest returns zero (carry  on  matching)  by
719           default,  but you can use a \C item in a data line (as described above)
720           to change this and other parameters of the callout.
721    
722           Inserting callouts can be helpful when using pcretest to check  compli-
723           cated  regular expressions. For further information about callouts, see
724           the pcrecallout documentation.
725    
726    
727    NON-PRINTING CHARACTERS
728    
729           When pcretest is outputting text in the compiled version of a  pattern,
730           bytes  other  than 32-126 are always treated as non-printing characters
731           are are therefore shown as hex escapes.
732    
733           When pcretest is outputting text that is a matched part  of  a  subject
734           string,  it behaves in the same way, unless a different locale has been
735           set for the  pattern  (using  the  /L  modifier).  In  this  case,  the
736           isprint() function to distinguish printing and non-printing characters.
737    
738    
739    SAVING AND RELOADING COMPILED PATTERNS
740    
741           The  facilities  described  in  this section are not available when the
742           POSIX interface to PCRE is being used, that is,  when  the  /P  pattern
743           modifier is specified.
744    
745           When the POSIX interface is not in use, you can cause pcretest to write
746           a compiled pattern to a file, by following the modifiers with >  and  a
747           file name.  For example:
748    
749             /pattern/im >/some/file
750    
751           See  the pcreprecompile documentation for a discussion about saving and
752           re-using compiled patterns.  Note that if the pattern was  successfully
753           studied with JIT optimization, the JIT data cannot be saved.
754    
755           The  data  that  is  written  is  binary. The first eight bytes are the
756           length of the compiled pattern data  followed  by  the  length  of  the
757           optional  study  data,  each  written as four bytes in big-endian order
758           (most significant byte first). If there is no study  data  (either  the
759           pattern was not studied, or studying did not return any data), the sec-
760           ond length is zero. The lengths are followed by an exact  copy  of  the
761           compiled  pattern.  If  there is additional study data, this (excluding
762           any JIT data) follows immediately after  the  compiled  pattern.  After
763           writing the file, pcretest expects to read a new pattern.
764    
765           A  saved  pattern  can  be reloaded into pcretest by specifying < and a
766           file name instead of a pattern. The name of the file must not contain a
767           < character, as otherwise pcretest will interpret the line as a pattern
768           delimited by < characters.  For example:
769    
770              re> </some/file
771             Compiled pattern loaded from /some/file
772             No study data
773    
774           If the pattern was previously studied with the  JIT  optimization,  the
775           JIT  information cannot be saved and restored, and so is lost. When the
776           pattern has been loaded, pcretest proceeds to read data  lines  in  the
777           usual way.
778    
779           You  can copy a file written by pcretest to a different host and reload
780           it there, even if the new host has opposite endianness to  the  one  on
781           which  the pattern was compiled. For example, you can compile on an i86
782           machine and run on a SPARC machine.
783    
784           File names for saving and reloading can be absolute  or  relative,  but
785           note  that the shell facility of expanding a file name that starts with
786           a tilde (~) is not available.
787    
788           The ability to save and reload files in pcretest is intended for  test-
789           ing  and experimentation. It is not intended for production use because
790           only a single pattern can be written to a file. Furthermore,  there  is
791           no  facility  for  supplying  custom  character  tables  for use with a
792           reloaded pattern. If the original  pattern  was  compiled  with  custom
793           tables,  an  attempt to match a subject string using a reloaded pattern
794           is likely to cause pcretest to crash.  Finally, if you attempt to  load
795           a file that is not in the correct format, the result is undefined.
796    
797    
798    SEE ALSO
799    
800           pcre(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematching(3), pcrepar-
801           tial(d), pcrepattern(3), pcreprecompile(3).
802    
803    
804    AUTHOR
805    
806           Philip Hazel
807           University Computing Service
808           Cambridge CB2 3QH, England.
809    
810    
811    REVISION
812    
813           Last updated: 02 December 2011
814           Copyright (c) 1997-2011 University of Cambridge.

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