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1    PCRETEST(1)                                                        PCRETEST(1)
2    
3    
4  NAME  NAME
5       pcretest - a program  for  testing  Perl-compatible  regular         pcretest - a program for testing Perl-compatible regular expressions.
      expressions.  
6    
7    
8  SYNOPSIS  SYNOPSIS
      pcretest [-d] [-i] [-m] [-o osize] [-p] [-t] [source]  [des-  
      tination]  
9    
10       pcretest was written as a test program for the PCRE  regular         pcretest [options] [source] [destination]
11       expression  library  itself,  but  it  can  also be used for  
12       experimenting  with  regular  expressions.   This   document         pcretest  was written as a test program for the PCRE regular expression
13       describes  the  features of the test program; for details of         library itself, but it can also be used for experimenting with  regular
14       the regular  expressions  themselves,  see  the  pcrepattern         expressions.  This document describes the features of the test program;
15       documentation.  For details of PCRE and its options, see the         for details of the regular expressions themselves, see the  pcrepattern
16       pcreapi documentation.         documentation. For details of the PCRE library function calls and their
17           options, see the pcreapi documentation.
18    
19    
20  OPTIONS  OPTIONS
21    
22           -b        Behave as if each regex has the /B (show bytecode)  modifier;
23                     the internal form is output after compilation.
24    
25       -C        Output the version number of the PCRE library, and         -C        Output the version number of the PCRE library, and all avail-
26                 all   available  information  about  the  optional                   able  information  about  the  optional  features  that   are
27                 features that are included, and then exit.                   included, and then exit.
28    
29       -d        Behave as if each regex had the /D  modifier  (see         -d        Behave  as  if  each  regex  has the /D (debug) modifier; the
30                 below); the internal form is output after compila-                   internal form and information about the compiled  pattern  is
31                 tion.                   output after compilation; -d is equivalent to -b -i.
32    
33       -i        Behave as if  each  regex  had  the  /I  modifier;         -dfa      Behave  as if each data line contains the \D escape sequence;
34                 information  about  the  compiled pattern is given                   this    causes    the    alternative    matching    function,
35                 after compilation.                   pcre_dfa_exec(),   to   be   used  instead  of  the  standard
36                     pcre_exec() function (more detail is given below).
37       -m        Output the size of each compiled pattern after  it  
38                 has been compiled. This is equivalent to adding /M         -help     Output a brief summary these options and then exit.
39                 to each regular expression. For compatibility with  
40                 earlier  versions of pcretest, -s is a synonym for         -i        Behave as if each regex  has  the  /I  modifier;  information
41                 -m.                   about the compiled pattern is given after compilation.
42    
43       -o osize  Set the number of elements in  the  output  vector         -M        Behave  as if each data line contains the \M escape sequence;
44                 that  is  used  when calling PCRE to be osize. The                   this causes PCRE to  discover  the  minimum  MATCH_LIMIT  and
45                 default value is 45, which is enough for  14  cap-                   MATCH_LIMIT_RECURSION settings by calling pcre_exec() repeat-
46                 turing  subexpressions.  The  vector  size  can be                   edly with different limits.
47                 changed for individual matching calls by including  
48                 \O in the data line (see below).         -m        Output the size of each compiled pattern after  it  has  been
49                     compiled.  This  is  equivalent  to adding /M to each regular
50       -p        Behave as if each regex has /P modifier; the POSIX                   expression.  For  compatibility  with  earlier  versions   of
51                 wrapper  API  is  used  to  call PCRE. None of the                   pcretest, -s is a synonym for -m.
52                 other options has any effect when -p is set.  
53           -o osize  Set  the number of elements in the output vector that is used
54       -t        Run each compile, study, and match many times with                   when calling pcre_exec() or pcre_dfa_exec() to be osize.  The
55                 a  timer, and output resulting time per compile or                   default  value is 45, which is enough for 14 capturing subex-
56                 match (in milliseconds). Do not set  -t  with  -m,                   pressions  for  pcre_exec()  or  22  different  matches   for
57                 because  you  will  then get the size output 20000                   pcre_dfa_exec().  The vector size can be changed for individ-
58                 times and the timing will be distorted.                   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  DESCRIPTION
85    
86       If pcretest is given two filename arguments, it  reads  from         If  pcretest  is  given two filename arguments, it reads from the first
87       the  first and writes to the second. If it is given only one         and writes to the second. If it is given only one filename argument, it
88       filename argument, it reads from that  file  and  writes  to         reads  from  that  file  and writes to stdout. Otherwise, it reads from
89       stdout. Otherwise, it reads from stdin and writes to stdout,         stdin and writes to stdout, and prompts for each line of  input,  using
90       and prompts for each line of input, using  "re>"  to  prompt         "re>" to prompt for regular expressions, and "data>" to prompt for data
91       for  regular  expressions,  and  "data>"  to prompt for data         lines.
92       lines.  
93           When pcretest is built, a configuration  option  can  specify  that  it
94       The program handles any number of sets of input on a  single         should  be  linked  with the libreadline library. When this is done, if
95       input  file.  Each set starts with a regular expression, and         the input is from a terminal, it is read using the readline() function.
96       continues with any  number  of  data  lines  to  be  matched         This  provides line-editing and history facilities. The output from the
97       against the pattern.         -help option states whether or not readline() will be used.
98    
99       Each line is matched separately and  independently.  If  you         The program handles any number of sets of input on a single input file.
100       want  to  do  multiple-line  matches, you have to use the \n         Each  set starts with a regular expression, and continues with any num-
101       escape sequence in a single line of input to encode the new-         ber of data lines to be matched against the pattern.
102       line  characters.  The maximum length of data line is 30,000  
103       characters.         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       An empty line signals the end of the data  lines,  at  which         \r\n, etc., depending on the newline setting) in a single line of input
106       point  a new regular expression is read. The regular expres-         to  encode  the  newline  sequences. There is no limit on the length of
107       sions are given enclosed in  any  non-alphameric  delimiters         data lines; the input buffer is automatically extended  if  it  is  too
108       other than backslash, for example         small.
109    
110         /(a|bc)x+yz/         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       White space before the initial delimiter is ignored. A regu-         in any non-alphanumeric delimiters other than backslash, for example:
113       lar expression may be continued over several input lines, in  
114       which case the newline characters are included within it. It           /(a|bc)x+yz/
115       is  possible  to include the delimiter within the pattern by  
116       escaping it, for example         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         /abc\/def/         line  characters  are included within it. It is possible to include the
119           delimiter within the pattern by escaping it, for example
120       If you do so, the escape and the delimiter form part of  the  
121       pattern,  but  since  delimiters  are always non-alphameric,           /abc\/def/
122       this does not affect its interpretation.  If the terminating  
123       delimiter  is immediately followed by a backslash, for exam-         If you do so, the escape and the delimiter form part  of  the  pattern,
124       ple,         but  since delimiters are always non-alphanumeric, this does not affect
125           its interpretation.  If the terminating delimiter is  immediately  fol-
126         /abc/\         lowed by a backslash, for example,
127    
128       then a backslash is added to the end of the pattern. This is           /abc/\
129       done  to  provide  a way of testing the error condition that  
130       arises if a pattern finishes with a backslash, because         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         /abc\/         finishes with a backslash, because
133    
134       is interpreted as the first line of a  pattern  that  starts           /abc\/
135       with  "abc/",  causing  pcretest  to read the next line as a  
136       continuation of the regular expression.         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  PATTERN MODIFIERS
142    
143       The pattern may be followed by i, m, s,  or  x  to  set  the         A  pattern may be followed by any number of modifiers, which are mostly
144       PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED         single characters. Following Perl usage, these are  referred  to  below
145       options, respectively. For example:         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         /caseless/i         modifiers.  Whitespace  may  appear between the final pattern delimiter
148           and the first modifier, and between the modifiers themselves.
149       These modifier letters have the same effect as  they  do  in  
150       Perl.  There  are  others  that set PCRE options that do not         The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
151       correspond to anything in Perl:  /A, /E, /N, /U, and /X  set         PCRE_DOTALL,  or  PCRE_EXTENDED  options,  respectively, when pcre_com-
152       PCRE_ANCHORED,   PCRE_DOLLAR_ENDONLY,  PCRE_NO_AUTO_CAPTURE,         pile() is called. These four modifier letters have the same  effect  as
153       PCRE_UNGREEDY, and PCRE_EXTRA respectively.         they do in Perl. For example:
154    
155       Searching for  all  possible  matches  within  each  subject           /caseless/i
156       string  can  be  requested  by  the /g or /G modifier. After  
157       finding  a  match,  PCRE  is  called  again  to  search  the         The following table shows additional modifiers for setting PCRE options
158       remainder  of  the subject string. The difference between /g         that do not correspond to anything in Perl:
159       and /G is that the former uses the startoffset  argument  to  
160       pcre_exec()  to  start  searching  at a new point within the           /A              PCRE_ANCHORED
161       entire string (which is in effect what Perl  does),  whereas           /C              PCRE_AUTO_CALLOUT
162       the  latter  passes over a shortened substring. This makes a           /E              PCRE_DOLLAR_ENDONLY
163       difference to the matching process  if  the  pattern  begins           /f              PCRE_FIRSTLINE
164       with a lookbehind assertion (including \b or \B).           /J              PCRE_DUPNAMES
165             /N              PCRE_NO_AUTO_CAPTURE
166       If any call to pcre_exec() in a /g or /G sequence matches an           /U              PCRE_UNGREEDY
167       empty  string,  the next call is done with the PCRE_NOTEMPTY           /X              PCRE_EXTRA
168       and PCRE_ANCHORED flags set in order to search for  another,           /<JS>           PCRE_JAVASCRIPT_COMPAT
169       non-empty,  match  at  the same point.  If this second match           /<cr>           PCRE_NEWLINE_CR
170       fails, the start offset is advanced by one, and  the  normal           /<lf>           PCRE_NEWLINE_LF
171       match  is  retried.  This imitates the way Perl handles such           /<crlf>         PCRE_NEWLINE_CRLF
172       cases when using the /g modifier or the split() function.           /<anycrlf>      PCRE_NEWLINE_ANYCRLF
173             /<any>          PCRE_NEWLINE_ANY
174       There are a number of other modifiers  for  controlling  the           /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
175       way pcretest operates.           /<bsr_unicode>  PCRE_BSR_UNICODE
176    
177       The /+ modifier requests that as well as outputting the sub-         Those specifying line ending sequences are literal  strings  as  shown,
178       string  that  matched the entire pattern, pcretest should in         but  the  letters  can  be  in either case. This example sets multiline
179       addition output the remainder of the subject string. This is         matching with CRLF as the line ending sequence:
180       useful  for tests where the subject contains multiple copies  
181       of the same substring.           /^abc/m<crlf>
182    
183       The /L modifier must be followed directly by the name  of  a         Details of the meanings of these PCRE options are given in the  pcreapi
184       locale, for example,         documentation.
185    
186         /pattern/Lfr     Finding all matches in a string
187    
188       For this reason, it must be the last  modifier  letter.  The         Searching  for  all  possible matches within each subject string can be
189       given  locale is set, pcre_maketables() is called to build a         requested by the /g or /G modifier. After  finding  a  match,  PCRE  is
190       set of character tables for the locale,  and  this  is  then         called again to search the remainder of the subject string. The differ-
191       passed  to pcre_compile() when compiling the regular expres-         ence between /g and /G is that the former uses the startoffset argument
192       sion. Without an /L modifier, NULL is passed as  the  tables         to  pcre_exec()  to  start  searching  at a new point within the entire
193       pointer; that is, /L applies only to the expression on which         string (which is in effect what Perl does), whereas the  latter  passes
194       it appears.         over  a  shortened  substring.  This makes a difference to the matching
195           process if the pattern begins with a lookbehind assertion (including \b
196       The /I modifier requests that  pcretest  output  information         or \B).
197       about the compiled expression (whether it is anchored, has a  
198       fixed first character, and so on). It does this  by  calling         If  any  call  to  pcre_exec()  in a /g or /G sequence matches an empty
199       pcre_fullinfo()  after  compiling an expression, and output-         string, the next call is done with the PCRE_NOTEMPTY and  PCRE_ANCHORED
200       ting the information it gets back. If the  pattern  is  stu-         flags  set in order to search for another, non-empty, match at the same
201       died, the results of that are also output.         point.  If this second match fails, the start  offset  is  advanced  by
202           one,  and  the normal match is retried. This imitates the way Perl han-
203       The /D modifier is a  PCRE  debugging  feature,  which  also         dles such cases when using the /g modifier or the split() function.
204       assumes /I.  It causes the internal form of compiled regular  
205       expressions to be output after compilation. If  the  pattern     Other modifiers
206       was studied, the information returned is also output.  
207           There are yet more modifiers for controlling the way pcretest operates.
208       The /S modifier causes pcre_study() to be called  after  the  
209       expression  has been compiled, and the results used when the         The /+ modifier requests that as well as outputting the substring  that
210       expression is matched.         matched  the  entire  pattern,  pcretest  should in addition output the
211           remainder of the subject string. This is useful  for  tests  where  the
212       The /M modifier causes the size of memory block used to hold         subject contains multiple copies of the same substring.
213       the compiled pattern to be output.  
214           The  /B modifier is a debugging feature. It requests that pcretest out-
215       The /P modifier causes pcretest to call PCRE via  the  POSIX         put a representation of the compiled byte code after compilation.  Nor-
216       wrapper  API  rather than its native API. When this is done,         mally  this  information contains length and offset values; however, if
217       all other modifiers except  /i,  /m,  and  /+  are  ignored.         /Z is also present, this data is replaced by spaces. This is a  special
218       REG_ICASE is set if /i is present, and REG_NEWLINE is set if         feature for use in the automatic test scripts; it ensures that the same
219       /m    is    present.    The    wrapper    functions    force         output is generated for different internal link sizes.
220       PCRE_DOLLAR_ENDONLY    always,    and   PCRE_DOTALL   unless  
221       REG_NEWLINE is set.         The /L modifier must be followed directly by the name of a locale,  for
222           example,
223       The /8 modifier  causes  pcretest  to  call  PCRE  with  the  
224       PCRE_UTF8  option set. This turns on support for UTF-8 char-           /pattern/Lfr_FR
225       acter handling in PCRE, provided that it was  compiled  with  
226       this  support  enabled.  This  modifier also causes any non-         For this reason, it must be the last modifier. The given locale is set,
227       printing characters in output strings to  be  printed  using         pcre_maketables() is called to build a set of character tables for  the
228       the \x{hh...} notation if they are valid UTF-8 sequences.         locale,  and  this  is then passed to pcre_compile() when compiling the
229           regular expression. Without an /L  modifier,  NULL  is  passed  as  the
230       If the /? modifier is used with /8, it  causes  pcretest  to         tables  pointer; that is, /L applies only to the expression on which it
231       call  pcre_compile()  with the PCRE_NO_UTF8_CHECK option, to         appears.
232       suppress the checking of the string for UTF-8 validity.  
233           The /I modifier requests that pcretest  output  information  about  the
234           compiled  pattern (whether it is anchored, has a fixed first character,
235           and so on). It does this by calling pcre_fullinfo() after  compiling  a
236           pattern.  If  the pattern is studied, the results of that are also out-
237           put.
238    
239           The /D modifier is a PCRE debugging feature, and is equivalent to  /BI,
240           that is, both the /B and the /I modifiers.
241    
242           The /F modifier causes pcretest to flip the byte order of the fields in
243           the compiled pattern that  contain  2-byte  and  4-byte  numbers.  This
244           facility  is  for testing the feature in PCRE that allows it to execute
245           patterns that were compiled on a host with a different endianness. This
246           feature  is  not  available  when  the POSIX interface to PCRE is being
247           used, that is, when the /P pattern modifier is specified. See also  the
248           section about saving and reloading compiled patterns below.
249    
250           The  /S  modifier causes pcre_study() to be called after the expression
251           has been compiled, and the results used when the expression is matched.
252    
253           The /M modifier causes the size of memory block used to hold  the  com-
254           piled pattern to be output.
255    
256           The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
257           rather than its native API. When this  is  done,  all  other  modifiers
258           except  /i,  /m, and /+ are ignored. REG_ICASE is set if /i is present,
259           and REG_NEWLINE is set if /m is present. The  wrapper  functions  force
260           PCRE_DOLLAR_ENDONLY always, and PCRE_DOTALL unless REG_NEWLINE is set.
261    
262           The  /8 modifier causes pcretest to call PCRE with the PCRE_UTF8 option
263           set. This turns on support for UTF-8 character handling in  PCRE,  pro-
264           vided  that  it  was  compiled with this support enabled. This modifier
265           also causes any non-printing characters in output strings to be printed
266           using the \x{hh...} notation if they are valid UTF-8 sequences.
267    
268           If  the  /?  modifier  is  used  with  /8,  it  causes pcretest to call
269           pcre_compile() with the  PCRE_NO_UTF8_CHECK  option,  to  suppress  the
270           checking of the string for UTF-8 validity.
271    
272    
273    DATA LINES
274    
275           Before  each  data  line is passed to pcre_exec(), leading and trailing
276           whitespace is removed, and it is then scanned for \  escapes.  Some  of
277           these  are  pretty esoteric features, intended for checking out some of
278           the more complicated features of PCRE. If you are just  testing  "ordi-
279           nary"  regular  expressions,  you probably don't need any of these. The
280           following escapes are recognized:
281    
282             \a         alarm (BEL, \x07)
283             \b         backspace (\x08)
284             \e         escape (\x27)
285             \f         formfeed (\x0c)
286             \n         newline (\x0a)
287             \qdd       set the PCRE_MATCH_LIMIT limit to dd
288                          (any number of digits)
289             \r         carriage return (\x0d)
290             \t         tab (\x09)
291             \v         vertical tab (\x0b)
292             \nnn       octal character (up to 3 octal digits)
293             \xhh       hexadecimal character (up to 2 hex digits)
294             \x{hh...}  hexadecimal character, any number of digits
295                          in UTF-8 mode
296             \A         pass the PCRE_ANCHORED option to pcre_exec()
297                          or pcre_dfa_exec()
298             \B         pass the PCRE_NOTBOL option to pcre_exec()
299                          or pcre_dfa_exec()
300             \Cdd       call pcre_copy_substring() for substring dd
301                          after a successful match (number less than 32)
302             \Cname     call pcre_copy_named_substring() for substring
303                          "name" after a successful match (name termin-
304                          ated by next non alphanumeric character)
305             \C+        show the current captured substrings at callout
306                          time
307             \C-        do not supply a callout function
308             \C!n       return 1 instead of 0 when callout number n is
309                          reached
310             \C!n!m     return 1 instead of 0 when callout number n is
311                          reached for the nth time
312             \C*n       pass the number n (may be negative) as callout
313                          data; this is used as the callout return value
314             \D         use the pcre_dfa_exec() match function
315             \F         only shortest match for pcre_dfa_exec()
316             \Gdd       call pcre_get_substring() for substring dd
317                          after a successful match (number less than 32)
318             \Gname     call pcre_get_named_substring() for substring
319                          "name" after a successful match (name termin-
320                          ated by next non-alphanumeric character)
321             \L         call pcre_get_substringlist() after a
322                          successful match
323             \M         discover the minimum MATCH_LIMIT and
324                          MATCH_LIMIT_RECURSION settings
325             \N         pass the PCRE_NOTEMPTY option to pcre_exec()
326                          or pcre_dfa_exec()
327             \Odd       set the size of the output vector passed to
328                          pcre_exec() to dd (any number of digits)
329             \P         pass the PCRE_PARTIAL option to pcre_exec()
330                          or pcre_dfa_exec()
331             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
332                          (any number of digits)
333             \R         pass the PCRE_DFA_RESTART option to pcre_dfa_exec()
334             \S         output details of memory get/free calls during matching
335             \Z         pass the PCRE_NOTEOL option to pcre_exec()
336                          or pcre_dfa_exec()
337             \?         pass the PCRE_NO_UTF8_CHECK option to
338                          pcre_exec() or pcre_dfa_exec()
339             \>dd       start the match at offset dd (any number of digits);
340                          this sets the startoffset argument for pcre_exec()
341                          or pcre_dfa_exec()
342             \<cr>      pass the PCRE_NEWLINE_CR option to pcre_exec()
343                          or pcre_dfa_exec()
344             \<lf>      pass the PCRE_NEWLINE_LF option to pcre_exec()
345                          or pcre_dfa_exec()
346             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre_exec()
347                          or pcre_dfa_exec()
348             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre_exec()
349                          or pcre_dfa_exec()
350             \<any>     pass the PCRE_NEWLINE_ANY option to pcre_exec()
351                          or pcre_dfa_exec()
352    
353           The escapes that specify line ending  sequences  are  literal  strings,
354           exactly as shown. No more than one newline setting should be present in
355           any data line.
356    
357           A backslash followed by anything else just escapes the  anything  else.
358           If  the very last character is a backslash, it is ignored. This gives a
359           way of passing an empty line as data, since a real  empty  line  termi-
360           nates the data input.
361    
362           If  \M  is present, pcretest calls pcre_exec() several times, with dif-
363           ferent values in the match_limit and  match_limit_recursion  fields  of
364           the  pcre_extra  data structure, until it finds the minimum numbers for
365           each parameter that allow pcre_exec() to complete. The match_limit num-
366           ber  is  a  measure of the amount of backtracking that takes place, and
367           checking it out can be instructive. For most simple matches, the number
368           is  quite  small,  but for patterns with very large numbers of matching
369           possibilities, it can become large very quickly with increasing  length
370           of subject string. The match_limit_recursion number is a measure of how
371           much stack (or, if PCRE is compiled with  NO_RECURSE,  how  much  heap)
372           memory is needed to complete the match attempt.
373    
374           When  \O  is  used, the value specified may be higher or lower than the
375           size set by the -O command line option (or defaulted to 45); \O applies
376           only to the call of pcre_exec() for the line in which it appears.
377    
378           If  the /P modifier was present on the pattern, causing the POSIX wrap-
379           per API to be used, the only option-setting  sequences  that  have  any
380           effect  are \B and \Z, causing REG_NOTBOL and REG_NOTEOL, respectively,
381           to be passed to regexec().
382    
383           The use of \x{hh...} to represent UTF-8 characters is not dependent  on
384           the  use  of  the  /8 modifier on the pattern. It is recognized always.
385           There may be any number of hexadecimal digits inside  the  braces.  The
386           result  is  from  one  to  six bytes, encoded according to the original
387           UTF-8 rules of RFC 2279. This allows for  values  in  the  range  0  to
388           0x7FFFFFFF.  Note  that not all of those are valid Unicode code points,
389           or indeed valid UTF-8 characters according to the later  rules  in  RFC
390           3629.
391    
392    
393    THE ALTERNATIVE MATCHING FUNCTION
394    
395           By   default,  pcretest  uses  the  standard  PCRE  matching  function,
396           pcre_exec() to match each data line. From release 6.0, PCRE supports an
397           alternative  matching  function,  pcre_dfa_test(),  which operates in a
398           different way, and has some restrictions. The differences  between  the
399           two functions are described in the pcrematching documentation.
400    
401           If  a data line contains the \D escape sequence, or if the command line
402           contains the -dfa option, the alternative matching function is  called.
403           This function finds all possible matches at a given point. If, however,
404           the \F escape sequence is present in the data line, it stops after  the
405           first match is found. This is always the shortest possible match.
406    
407    
408    DEFAULT OUTPUT FROM PCRETEST
409    
410           This  section  describes  the output when the normal matching function,
411           pcre_exec(), is being used.
412    
413           When a match succeeds, pcretest outputs the list of captured substrings
414           that  pcre_exec()  returns,  starting with number 0 for the string that
415           matched the whole pattern. Otherwise, it outputs "No match" or "Partial
416           match"  when  pcre_exec() returns PCRE_ERROR_NOMATCH or PCRE_ERROR_PAR-
417           TIAL, respectively, and otherwise the PCRE negative error number.  Here
418           is an example of an interactive pcretest run.
419    
420             $ pcretest
421             PCRE version 7.0 30-Nov-2006
422    
423               re> /^abc(\d+)/
424             data> abc123
425              0: abc123
426              1: 123
427             data> xyz
428             No match
429    
430           Note  that unset capturing substrings that are not followed by one that
431           is set are not returned by pcre_exec(), and are not shown by  pcretest.
432           In  the following example, there are two capturing substrings, but when
433           the first data line is matched, the  second,  unset  substring  is  not
434           shown.  An "internal" unset substring is shown as "<unset>", as for the
435           second data line.
436    
437               re> /(a)|(b)/
438             data> a
439              0: a
440              1: a
441             data> b
442              0: b
443              1: <unset>
444              2: b
445    
446           If the strings contain any non-printing characters, they are output  as
447           \0x  escapes,  or  as \x{...} escapes if the /8 modifier was present on
448           the pattern. See below for the definition of  non-printing  characters.
449           If  the pattern has the /+ modifier, the output for substring 0 is fol-
450           lowed by the the rest of the subject string, identified  by  "0+"  like
451           this:
452    
453               re> /cat/+
454             data> cataract
455              0: cat
456              0+ aract
457    
458           If  the  pattern  has  the /g or /G modifier, the results of successive
459           matching attempts are output in sequence, like this:
460    
461               re> /\Bi(\w\w)/g
462             data> Mississippi
463              0: iss
464              1: ss
465              0: iss
466              1: ss
467              0: ipp
468              1: pp
469    
470           "No match" is output only if the first match attempt fails.
471    
472           If any of the sequences \C, \G, or \L are present in a data  line  that
473           is  successfully  matched,  the substrings extracted by the convenience
474           functions are output with C, G, or L after the string number instead of
475           a colon. This is in addition to the normal full list. The string length
476           (that is, the return from the extraction function) is given  in  paren-
477           theses after each string for \C and \G.
478    
479           Note that whereas patterns can be continued over several lines (a plain
480           ">" prompt is used for continuations), data lines may not. However new-
481           lines  can  be included in data by means of the \n escape (or \r, \r\n,
482           etc., depending on the newline sequence setting).
483    
484    
485    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
486    
487           When the alternative matching function, pcre_dfa_exec(),  is  used  (by
488           means  of  the \D escape sequence or the -dfa command line option), the
489           output consists of a list of all the matches that start  at  the  first
490           point in the subject where there is at least one match. For example:
491    
492               re> /(tang|tangerine|tan)/
493             data> yellow tangerine\D
494              0: tangerine
495              1: tang
496              2: tan
497    
498           (Using  the  normal  matching function on this data finds only "tang".)
499           The longest matching string is always given first (and numbered zero).
500    
501           If /g is present on the pattern, the search for further matches resumes
502           at the end of the longest match. For example:
503    
504               re> /(tang|tangerine|tan)/g
505             data> yellow tangerine and tangy sultana\D
506              0: tangerine
507              1: tang
508              2: tan
509              0: tang
510              1: tan
511              0: tan
512    
513           Since  the  matching  function  does not support substring capture, the
514           escape sequences that are concerned with captured  substrings  are  not
515           relevant.
516    
517    
518    RESTARTING AFTER A PARTIAL MATCH
519    
520           When the alternative matching function has given the PCRE_ERROR_PARTIAL
521           return, indicating that the subject partially matched the pattern,  you
522           can  restart  the match with additional subject data by means of the \R
523           escape sequence. For example:
524    
525               re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
526             data> 23ja\P\D
527             Partial match: 23ja
528             data> n05\R\D
529              0: n05
530    
531           For further information about partial  matching,  see  the  pcrepartial
532           documentation.
533    
534    
535  CALLOUTS  CALLOUTS
536    
537       If the pattern contains  any  callout  requests,  pcretest's         If  the pattern contains any callout requests, pcretest's callout func-
538       callout function will be called. By default, it displays the         tion is called during matching. This works  with  both  matching  func-
539       callout number, and the start and current positions  in  the         tions. By default, the called function displays the callout number, the
540       text at the callout time. For example, the output         start and current positions in the text at the callout  time,  and  the
541           next pattern item to be tested. For example, the output
542         --->pqrabcdef  
543           0    ^  ^           --->pqrabcdef
544               0    ^  ^     \d
545       indicates that callout number 0 occurred for a match attempt  
546       starting at the fourth character of the subject string, when         indicates  that  callout number 0 occurred for a match attempt starting
547       the pointer was at the seventh character. The callout  func-         at the fourth character of the subject string, when the pointer was  at
548       tion returns zero (carry on matching) by default.         the  seventh  character of the data, and when the next pattern item was
549           \d. Just one circumflex is output if the start  and  current  positions
550       Inserting callouts may be helpful  when  using  pcretest  to         are the same.
551       check  complicated regular expressions. For further informa-  
552       tion about callouts, see the pcrecallout documentation.         Callouts numbered 255 are assumed to be automatic callouts, inserted as
553           a result of the /C pattern modifier. In this case, instead  of  showing
554       For testing the PCRE library, additional control of  callout         the  callout  number, the offset in the pattern, preceded by a plus, is
555       behaviour  is available via escape sequences in the data, as         output. For example:
556       described in the following section.  In  particular,  it  is  
557       possible to pass in a number as callout data (the default is             re> /\d?[A-E]\*/C
558       zero). If the callout function receives a  non-zero  number,           data> E*
559       it returns that value instead of zero.           --->E*
560              +0 ^      \d?
561              +3 ^      [A-E]
562              +8 ^^     \*
563             +10 ^ ^
564              0: E*
565    
566           The callout function in pcretest returns zero (carry  on  matching)  by
567           default,  but you can use a \C item in a data line (as described above)
568           to change this.
569    
570           Inserting callouts can be helpful when using pcretest to check  compli-
571           cated  regular expressions. For further information about callouts, see
572           the pcrecallout documentation.
573    
574    
575    NON-PRINTING CHARACTERS
576    
577           When pcretest is outputting text in the compiled version of a  pattern,
578           bytes  other  than 32-126 are always treated as non-printing characters
579           are are therefore shown as hex escapes.
580    
581           When pcretest is outputting text that is a matched part  of  a  subject
582           string,  it behaves in the same way, unless a different locale has been
583           set for the  pattern  (using  the  /L  modifier).  In  this  case,  the
584           isprint() function to distinguish printing and non-printing characters.
585    
586    
587    SAVING AND RELOADING COMPILED PATTERNS
588    
589           The  facilities  described  in  this section are not available when the
590           POSIX inteface to PCRE is being used, that is, when the /P pattern mod-
591           ifier is specified.
592    
593           When the POSIX interface is not in use, you can cause pcretest to write
594           a compiled pattern to a file, by following the modifiers with >  and  a
595           file name.  For example:
596    
597             /pattern/im >/some/file
598    
599           See  the pcreprecompile documentation for a discussion about saving and
600           re-using compiled patterns.
601    
602           The data that is written is binary.  The  first  eight  bytes  are  the
603           length  of  the  compiled  pattern  data  followed by the length of the
604           optional study data, each written as four  bytes  in  big-endian  order
605           (most  significant  byte  first). If there is no study data (either the
606           pattern was not studied, or studying did not return any data), the sec-
607           ond  length  is  zero. The lengths are followed by an exact copy of the
608           compiled pattern. If there is additional study data, this follows imme-
609           diately  after  the  compiled pattern. After writing the file, pcretest
610           expects to read a new pattern.
611    
612           A saved pattern can be reloaded into pcretest by specifing < and a file
613           name  instead  of  a pattern. The name of the file must not contain a <
614           character, as otherwise pcretest will interpret the line as  a  pattern
615           delimited by < characters.  For example:
616    
617              re> </some/file
618             Compiled regex loaded from /some/file
619             No study data
620    
621           When  the pattern has been loaded, pcretest proceeds to read data lines
622           in the usual way.
623    
624           You can copy a file written by pcretest to a different host and  reload
625           it  there,  even  if the new host has opposite endianness to the one on
626           which the pattern was compiled. For example, you can compile on an  i86
627           machine and run on a SPARC machine.
628    
629           File  names  for  saving and reloading can be absolute or relative, but
630           note that the shell facility of expanding a file name that starts  with
631           a tilde (~) is not available.
632    
633           The  ability to save and reload files in pcretest is intended for test-
634           ing and experimentation. It is not intended for production use  because
635           only  a  single pattern can be written to a file. Furthermore, there is
636           no facility for supplying  custom  character  tables  for  use  with  a
637           reloaded  pattern.  If  the  original  pattern was compiled with custom
638           tables, an attempt to match a subject string using a  reloaded  pattern
639           is  likely to cause pcretest to crash.  Finally, if you attempt to load
640           a file that is not in the correct format, the result is undefined.
641    
642    
643  DATA LINES  SEE ALSO
644    
645       Before each data line is passed to pcre_exec(), leading  and         pcre(3), pcreapi(3), pcrecallout(3),  pcrematching(3),  pcrepartial(d),
646       trailing whitespace is removed, and it is then scanned for \         pcrepattern(3), pcreprecompile(3).
      escapes.  Some  of  these  are  pretty  esoteric   features,  
      intended  for  checking  out  some  of  the more complicated  
      features of PCRE. If you are just testing "ordinary" regular  
      expressions,  you probably don't need any of these. The fol-  
      lowing escapes 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)  
        \x{hh...}  hexadecimal character, any number of digits  
                     in UTF-8 mode  
        \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)  
        \Cname     call pcre_copy_named_substring() for substring  
   
                     "name" after a successful match (name termin-  
                     ated by next non alphanumeric character)  
        \C+        show the current captured substrings at callout  
                     time  
        \C-        do not supply a callout function  
        \C!n       return 1 instead of 0 when callout number n is  
                     reached  
        \C!n!m     return 1 instead of 0 when callout number n is  
                     reached for the nth time  
        \C*n       pass the number n (may be negative) as callout  
                     data  
        \Gdd       call pcre_get_substring() for substring dd  
                     after a successful match (any decimal number  
                     less than 32)  
        \Gname     call pcre_get_named_substring() for substring  
                     "name" after a successful match (name termin-  
                     ated by next non-alphanumeric character)  
        \L         call pcre_get_substringlist() after a  
                     successful match  
        \M         discover the minimum MATCH_LIMIT setting  
        \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()  
        \?         pass the PCRE_NO_UTF8_CHECK option to  
                     pcre_exec()  
   
      If \M is present, pcretest calls pcre_exec() several  times,  
      with  different  values  in  the  match_limit  field  of the  
      pcre_extra data structure, until it finds the minimum number  
      that is needed for pcre_exec() to complete. This number is a  
      measure of the amount of  recursion  and  backtracking  that  
      takes  place,  and  checking  it out can be instructive. For  
      most simple matches, the number is quite small, but for pat-  
      terns  with very large numbers of matching possibilities, it  
      can become large very quickly with increasing length of sub-  
      ject string.  
   
      When \O is used, it may be higher or lower than the size set  
      by  the  -O  option (or defaulted to 45); \O applies only to  
      the call of pcre_exec() for the line in which it appears.  
   
      A backslash followed by anything else just escapes the  any-  
      thing 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()  respec-  
      tively.  
      The use of \x{hh...} to represent UTF-8  characters  is  not  
      dependent  on  the use of the /8 modifier on the pattern. It  
      is recognized always. There may be any number of hexadecimal  
      digits  inside  the  braces.  The  result is from one to six  
      bytes, encoded according to the UTF-8 rules.  
   
   
 OUTPUT FROM PCRETEST  
   
      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 4.00 08-Jan-2003  
   
          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,  or  as  \x{...} escapes if the /8  
      modifier was present on the pattern. 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 the sequences \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 addi-  
      tion 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.  
647    
648    
649  AUTHOR  AUTHOR
650    
651       Philip Hazel <ph10@cam.ac.uk>         Philip Hazel
652       University Computing Service,         University Computing Service
653       Cambridge CB2 3QG, England.         Cambridge CB2 3QH, England.
654    
655    
656    REVISION
657    
658  Last updated: 20 August 2003         Last updated: 10 March 2009
659  Copyright (c) 1997-2003 University of Cambridge.         Copyright (c) 1997-2009 University of Cambridge.

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