/[pcre]/code/trunk/doc/pcretest.txt
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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] [input file [output file]]
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  and  pcre16  documentation.  The  input  for
18           pcretest is a sequence of regular expression patterns and strings to be
19  OPTIONS         matched, as described below. The output shows the result of each match.
20           Options  on  the command line and the patterns control PCRE options and
21           exactly what is output.
22       -C        Output the version number of the PCRE library, and  
23                 all   available  information  about  the  optional  
24                 features that are included, and then exit.  PCRE's 8-BIT and 16-BIT LIBRARIES
25    
26       -d        Behave as if each regex had the /D  modifier  (see         From release 8.30, two separate PCRE libraries can be built. The origi-
27                 below); the internal form is output after compila-         nal  one  supports  8-bit  character  strings, whereas the newer 16-bit
28                 tion.         library  supports  character  strings  encoded  in  16-bit  units.  The
29           pcretest  program  can  be  used to test both libraries. However, it is
30       -i        Behave as if  each  regex  had  the  /I  modifier;         itself still an 8-bit program, reading 8-bit input  and  writing  8-bit
31                 information  about  the  compiled pattern is given         output.  When testing the 16-bit library, the patterns and data strings
32                 after compilation.         are converted to 16-bit format before being passed to the PCRE  library
33           functions. Results are converted to 8-bit for output.
34       -m        Output the size of each compiled pattern after  it  
35                 has been compiled. This is equivalent to adding /M         References  to  functions  and structures of the form pcre[16]_xx below
36                 to each regular expression. For compatibility with         mean "pcre_xx when using the 8-bit library or pcre16_xx when using  the
37                 earlier  versions of pcretest, -s is a synonym for         16-bit library".
38                 -m.  
39    
40       -o osize  Set the number of elements in  the  output  vector  COMMAND LINE OPTIONS
41                 that  is  used  when calling PCRE to be osize. The  
42                 default value is 45, which is enough for  14  cap-         -16       If  both  the 8-bit and the 16-bit libraries have been built,
43                 turing  subexpressions.  The  vector  size  can be                   this option causes the 16-bit library to be used. If only the
44                 changed for individual matching calls by including                   16-bit library has been built, this is the default (so has no
45                 \O in the data line (see below).                   effect). If only the  8-bit  library  has  been  built,  this
46                     option causes an error.
47       -p        Behave as if each regex has /P modifier; the POSIX  
48                 wrapper  API  is  used  to  call PCRE. None of the         -b        Behave  as  if each pattern has the /B (show byte code) modi-
49                 other options has any effect when -p is set.                   fier; the internal form is output after compilation.
50    
51       -t        Run each compile, study, and match many times with         -C        Output the version number of the PCRE library, and all avail-
52                 a  timer, and output resulting time per compile or                   able   information  about  the  optional  features  that  are
53                 match (in milliseconds). Do not set  -t  with  -m,                   included, and then exit. All other options are ignored.
54                 because  you  will  then get the size output 20000  
55                 times and the timing will be distorted.         -C option Output information about a specific build-time  option,  then
56                     exit.  This functionality is intended for use in scripts such
57                     as RunTest. The following options output the value indicated:
58    
59                       linksize   the internal link size (2, 3, or 4)
60                       newline    the default newline setting:
61                                    CR, LF, CRLF, ANYCRLF, or ANY
62    
63                     The following options output 1 for true or zero for false:
64    
65                       jit        just-in-time support is available
66                       pcre16     the 16-bit library was built
67                       pcre8      the 8-bit library was built
68                       ucp        Unicode property support is available
69                       utf        UTF-8 and/or UTF-16 support is available
70    
71           -d        Behave as if each pattern has the /D  (debug)  modifier;  the
72                     internal  form  and information about the compiled pattern is
73                     output after compilation; -d is equivalent to -b -i.
74    
75           -dfa      Behave as if each data line contains the \D escape  sequence;
76                     this    causes    the    alternative    matching    function,
77                     pcre[16]_dfa_exec(), to  be  used  instead  of  the  standard
78                     pcre[16]_exec() function (more detail is given below).
79    
80           -help     Output a brief summary these options and then exit.
81    
82           -i        Behave  as  if  each pattern has the /I modifier; information
83                     about the compiled pattern is given after compilation.
84    
85           -M        Behave as if each data line contains the \M escape  sequence;
86                     this  causes  PCRE  to  discover  the minimum MATCH_LIMIT and
87                     MATCH_LIMIT_RECURSION  settings  by  calling  pcre[16]_exec()
88                     repeatedly with different limits.
89    
90           -m        Output  the  size  of each compiled pattern after it has been
91                     compiled. This is equivalent to adding  /M  to  each  regular
92                     expression. The size is given in bytes for both libraries.
93    
94           -o osize  Set  the number of elements in the output vector that is used
95                     when calling pcre[16]_exec()  or  pcre[16]_dfa_exec()  to  be
96                     osize.  The  default value is 45, which is enough for 14 cap-
97                     turing subexpressions for  pcre[16]_exec()  or  22  different
98                     matches  for  pcre[16]_dfa_exec().   The  vector  size can be
99                     changed for individual matching calls by including \O in  the
100                     data line (see below).
101    
102           -p        Behave  as  if  each  pattern  has the /P modifier; the POSIX
103                     wrapper API is used to call PCRE. None of the  other  options
104                     has  any  effect when -p is set. This option can be used only
105                     with the 8-bit library.
106    
107           -q        Do not output the version number of pcretest at the start  of
108                     execution.
109    
110           -S size   On  Unix-like  systems, set the size of the run-time stack to
111                     size megabytes.
112    
113           -s or -s+ Behave as if each pattern  has  the  /S  modifier;  in  other
114                     words,  force each pattern to be studied. If -s+ is used, all
115                     the JIT compile options are passed to pcre[16]_study(), caus-
116                     ing  just-in-time  optimization  to be set up if it is avail-
117                     able, for both full and partial matching. Specific  JIT  com-
118                     pile options can be selected by following -s+ with a digit in
119                     the range 1 to 7, which selects the JIT compile modes as fol-
120                     lows:
121    
122                       1  normal match only
123                       2  soft partial match only
124                       3  normal match and soft partial match
125                       4  hard partial match only
126                       6  soft and hard partial match
127                       7  all three modes (default)
128    
129                     If  -s++  is used instead of -s+ (with or without a following
130                     digit), the text "(JIT)" is added to the  first  output  line
131                     after a match or no match when JIT-compiled code was actually
132                     used.
133    
134           If the /I or /D option is present on a pattern (requesting output about
135           the  compiled pattern), information about the result of studying is not
136           included when studying is caused only by -s and neither -i  nor  -d  is
137           present  on the command line. This behaviour means that the output from
138           tests that are run with and without -s should be identical, except when
139           options that output information about the actual running of a match are
140           set.
141    
142           The -M, -t, and -tm options, which  give  information  about  resources
143           used,  are likely to produce different output with and without -s. Out-
144           put may also differ if the /C option is present on an  individual  pat-
145           tern.  This  uses  callouts to trace the the matching process, and this
146           may be different between studied and non-studied patterns. If the  pat-
147           tern contains (*MARK) items there may also be differences, for the same
148           reason. The -s command line option can be overridden for specific  pat-
149           terns that should never be studied (see the /S pattern modifier below).
150    
151           -t        Run  each  compile, study, and match many times with a timer,
152                     and output resulting time per compile or match (in  millisec-
153                     onds).  Do  not set -m with -t, because you will then get the
154                     size output a zillion times, and  the  timing  will  be  dis-
155                     torted.  You  can  control  the number of iterations that are
156                     used for timing by following -t with a number (as a  separate
157                     item on the command line). For example, "-t 1000" would iter-
158                     ate 1000 times. The default is to iterate 500000 times.
159    
160           -tm       This is like -t except that it times only the matching phase,
161                     not the compile or study phases.
162    
163    
164  DESCRIPTION  DESCRIPTION
165    
166       If pcretest is given two filename arguments, it  reads  from         If  pcretest  is  given two filename arguments, it reads from the first
167       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
168       filename argument, it reads from that  file  and  writes  to         reads  from  that  file  and writes to stdout. Otherwise, it reads from
169       stdout. Otherwise, it reads from stdin and writes to stdout,         stdin and writes to stdout, and prompts for each line of  input,  using
170       and prompts for each line of input, using  "re>"  to  prompt         "re>" to prompt for regular expressions, and "data>" to prompt for data
171       for  regular  expressions,  and  "data>"  to prompt for data         lines.
172       lines.  
173           When pcretest is built, a configuration  option  can  specify  that  it
174       The program handles any number of sets of input on a  single         should  be  linked  with the libreadline library. When this is done, if
175       input  file.  Each set starts with a regular expression, and         the input is from a terminal, it is read using the readline() function.
176       continues with any  number  of  data  lines  to  be  matched         This  provides line-editing and history facilities. The output from the
177       against the pattern.         -help option states whether or not readline() will be used.
178    
179       Each line is matched separately and  independently.  If  you         The program handles any number of sets of input on a single input file.
180       want  to  do  multiple-line  matches, you have to use the \n         Each  set starts with a regular expression, and continues with any num-
181       escape sequence in a single line of input to encode the new-         ber of data lines to be matched against the pattern.
182       line  characters.  The maximum length of data line is 30,000  
183       characters.         Each data line is matched separately and independently. If you want  to
184           do multi-line matches, you have to use the \n escape sequence (or \r or
185       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
186       point  a new regular expression is read. The regular expres-         to  encode  the  newline  sequences. There is no limit on the length of
187       sions are given enclosed in  any  non-alphameric  delimiters         data lines; the input buffer is automatically extended  if  it  is  too
188       other than backslash, for example         small.
189    
190         /(a|bc)x+yz/         An  empty  line signals the end of the data lines, at which point a new
191           regular expression is read. The regular expressions are given  enclosed
192       White space before the initial delimiter is ignored. A regu-         in any non-alphanumeric delimiters other than backslash, for example:
193       lar expression may be continued over several input lines, in  
194       which case the newline characters are included within it. It           /(a|bc)x+yz/
195       is  possible  to include the delimiter within the pattern by  
196       escaping it, for example         White  space before the initial delimiter is ignored. A regular expres-
197           sion may be continued over several input lines, in which case the  new-
198         /abc\/def/         line  characters  are included within it. It is possible to include the
199           delimiter within the pattern by escaping it, for example
200       If you do so, the escape and the delimiter form part of  the  
201       pattern,  but  since  delimiters  are always non-alphameric,           /abc\/def/
202       this does not affect its interpretation.  If the terminating  
203       delimiter  is immediately followed by a backslash, for exam-         If you do so, the escape and the delimiter form part  of  the  pattern,
204       ple,         but  since delimiters are always non-alphanumeric, this does not affect
205           its interpretation.  If the terminating delimiter is  immediately  fol-
206         /abc/\         lowed by a backslash, for example,
207    
208       then a backslash is added to the end of the pattern. This is           /abc/\
209       done  to  provide  a way of testing the error condition that  
210       arises if a pattern finishes with a backslash, because         then  a  backslash  is added to the end of the pattern. This is done to
211           provide a way of testing the error condition that arises if  a  pattern
212         /abc\/         finishes with a backslash, because
213    
214       is interpreted as the first line of a  pattern  that  starts           /abc\/
215       with  "abc/",  causing  pcretest  to read the next line as a  
216       continuation of the regular expression.         is  interpreted as the first line of a pattern that starts with "abc/",
217           causing pcretest to read the next line as a continuation of the regular
218           expression.
219    
220    
221  PATTERN MODIFIERS  PATTERN MODIFIERS
222    
223       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
224       PCRE_CASELESS, PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED         single characters. Following Perl usage, these are  referred  to  below
225       options, respectively. For example:         as,  for  example,  "the /i modifier", even though the delimiter of the
226           pattern need not always be a slash, and no slash is used  when  writing
227         /caseless/i         modifiers.  White  space may appear between the final pattern delimiter
228           and the first modifier, and between the modifiers themselves.
229       These modifier letters have the same effect as  they  do  in  
230       Perl.  There  are  others  that set PCRE options that do not         The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
231       correspond to anything in Perl:  /A, /E, /N, /U, and /X  set         PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre[16]_com-
232       PCRE_ANCHORED,   PCRE_DOLLAR_ENDONLY,  PCRE_NO_AUTO_CAPTURE,         pile() is called. These four modifier letters have the same  effect  as
233       PCRE_UNGREEDY, and PCRE_EXTRA respectively.         they do in Perl. For example:
234    
235       Searching for  all  possible  matches  within  each  subject           /caseless/i
236       string  can  be  requested  by  the /g or /G modifier. After  
237       finding  a  match,  PCRE  is  called  again  to  search  the         The  following  table  shows additional modifiers for setting PCRE com-
238       remainder  of  the subject string. The difference between /g         pile-time options that do not correspond to anything in Perl:
239       and /G is that the former uses the startoffset  argument  to  
240       pcre_exec()  to  start  searching  at a new point within the           /8              PCRE_UTF8           ) when using the 8-bit
241       entire string (which is in effect what Perl  does),  whereas           /?              PCRE_NO_UTF8_CHECK  )   library
242       the  latter  passes over a shortened substring. This makes a  
243       difference to the matching process  if  the  pattern  begins           /8              PCRE_UTF16          ) when using the 16-bit
244       with a lookbehind assertion (including \b or \B).           /?              PCRE_NO_UTF16_CHECK )   library
245    
246       If any call to pcre_exec() in a /g or /G sequence matches an           /A              PCRE_ANCHORED
247       empty  string,  the next call is done with the PCRE_NOTEMPTY           /C              PCRE_AUTO_CALLOUT
248       and PCRE_ANCHORED flags set in order to search for  another,           /E              PCRE_DOLLAR_ENDONLY
249       non-empty,  match  at  the same point.  If this second match           /f              PCRE_FIRSTLINE
250       fails, the start offset is advanced by one, and  the  normal           /J              PCRE_DUPNAMES
251       match  is  retried.  This imitates the way Perl handles such           /N              PCRE_NO_AUTO_CAPTURE
252       cases when using the /g modifier or the split() function.           /U              PCRE_UNGREEDY
253             /W              PCRE_UCP
254       There are a number of other modifiers  for  controlling  the           /X              PCRE_EXTRA
255       way pcretest operates.           /Y              PCRE_NO_START_OPTIMIZE
256             /<JS>           PCRE_JAVASCRIPT_COMPAT
257       The /+ modifier requests that as well as outputting the sub-           /<cr>           PCRE_NEWLINE_CR
258       string  that  matched the entire pattern, pcretest should in           /<lf>           PCRE_NEWLINE_LF
259       addition output the remainder of the subject string. This is           /<crlf>         PCRE_NEWLINE_CRLF
260       useful  for tests where the subject contains multiple copies           /<anycrlf>      PCRE_NEWLINE_ANYCRLF
261       of the same substring.           /<any>          PCRE_NEWLINE_ANY
262             /<bsr_anycrlf>  PCRE_BSR_ANYCRLF
263       The /L modifier must be followed directly by the name  of  a           /<bsr_unicode>  PCRE_BSR_UNICODE
264       locale, for example,  
265           The modifiers that are enclosed in angle brackets are  literal  strings
266         /pattern/Lfr         as  shown,  including the angle brackets, but the letters within can be
267           in either case.  This example sets multiline matching with CRLF as  the
268       For this reason, it must be the last  modifier  letter.  The         line ending sequence:
269       given  locale is set, pcre_maketables() is called to build a  
270       set of character tables for the locale,  and  this  is  then           /^abc/m<CRLF>
271       passed  to pcre_compile() when compiling the regular expres-  
272       sion. Without an /L modifier, NULL is passed as  the  tables         As  well  as turning on the PCRE_UTF8/16 option, the /8 modifier causes
273       pointer; that is, /L applies only to the expression on which         all non-printing characters in output strings to be printed  using  the
274       it appears.         \x{hh...}  notation. Otherwise, those less than 0x100 are output in hex
275           without the curly brackets.
276       The /I modifier requests that  pcretest  output  information  
277       about the compiled expression (whether it is anchored, has a         Full details of the PCRE options are given in  the  pcreapi  documenta-
278       fixed first character, and so on). It does this  by  calling         tion.
279       pcre_fullinfo()  after  compiling an expression, and output-  
280       ting the information it gets back. If the  pattern  is  stu-     Finding all matches in a string
281       died, the results of that are also output.  
282           Searching  for  all  possible matches within each subject string can be
283       The /D modifier is a  PCRE  debugging  feature,  which  also         requested by the /g or /G modifier. After  finding  a  match,  PCRE  is
284       assumes /I.  It causes the internal form of compiled regular         called again to search the remainder of the subject string. The differ-
285       expressions to be output after compilation. If  the  pattern         ence between /g and /G is that the former uses the startoffset argument
286       was studied, the information returned is also output.         to  pcre[16]_exec() to start searching at a new point within the entire
287           string (which is in effect what Perl does), whereas the  latter  passes
288       The /S modifier causes pcre_study() to be called  after  the         over  a  shortened  substring.  This makes a difference to the matching
289       expression  has been compiled, and the results used when the         process if the pattern begins with a lookbehind assertion (including \b
290       expression is matched.         or \B).
291    
292       The /M modifier causes the size of memory block used to hold         If  any call to pcre[16]_exec() in a /g or /G sequence matches an empty
293       the compiled pattern to be output.         string, the next  call  is  done  with  the  PCRE_NOTEMPTY_ATSTART  and
294           PCRE_ANCHORED  flags  set  in  order  to search for another, non-empty,
295       The /P modifier causes pcretest to call PCRE via  the  POSIX         match at the same point. If this second match fails, the  start  offset
296       wrapper  API  rather than its native API. When this is done,         is  advanced,  and  the  normal match is retried. This imitates the way
297       all other modifiers except  /i,  /m,  and  /+  are  ignored.         Perl handles such cases when using the /g modifier or the split() func-
298       REG_ICASE is set if /i is present, and REG_NEWLINE is set if         tion.  Normally,  the start offset is advanced by one character, but if
299       /m    is    present.    The    wrapper    functions    force         the newline convention recognizes CRLF as a newline,  and  the  current
300       PCRE_DOLLAR_ENDONLY    always,    and   PCRE_DOTALL   unless         character is CR followed by LF, an advance of two is used.
301       REG_NEWLINE is set.  
302       Other modifiers
303       The /8 modifier  causes  pcretest  to  call  PCRE  with  the  
304       PCRE_UTF8  option set. This turns on support for UTF-8 char-         There are yet more modifiers for controlling the way pcretest operates.
305       acter handling in PCRE, provided that it was  compiled  with  
306       this  support  enabled.  This  modifier also causes any non-         The  /+ modifier requests that as well as outputting the substring that
307       printing characters in output strings to  be  printed  using         matched the entire pattern, pcretest  should  in  addition  output  the
308       the \x{hh...} notation if they are valid UTF-8 sequences.         remainder  of  the  subject  string. This is useful for tests where the
309           subject contains multiple copies of the same substring. If the +  modi-
310       If the /? modifier is used with /8, it  causes  pcretest  to         fier  appears  twice, the same action is taken for captured substrings.
311       call  pcre_compile()  with the PCRE_NO_UTF8_CHECK option, to         In each case the remainder is output on the following line with a  plus
312       suppress the checking of the string for UTF-8 validity.         character  following  the  capture number. Note that this modifier must
313           not immediately follow the /S modifier because /S+ and /S++ have  other
314           meanings.
315    
316           The  /=  modifier  requests  that  the values of all potential captured
317           parentheses be output after a match. By default, only those up  to  the
318           highest one actually used in the match are output (corresponding to the
319           return code from pcre[16]_exec()). Values in the offsets vector  corre-
320           sponding to higher numbers should be set to -1, and these are output as
321           "<unset>". This modifier gives a way of checking that this  is  happen-
322           ing.
323    
324           The  /B modifier is a debugging feature. It requests that pcretest out-
325           put a representation of the compiled code after  compilation.  Normally
326           this  information  contains length and offset values; however, if /Z is
327           also present, this data is replaced by spaces. This is a  special  fea-
328           ture  for  use  in the automatic test scripts; it ensures that the same
329           output is generated for different internal link sizes.
330    
331           The /D modifier is a PCRE debugging feature, and is equivalent to  /BI,
332           that is, both the /B and the /I modifiers.
333    
334           The  /F  modifier  causes pcretest to flip the byte order of the 2-byte
335           and 4-byte fields in the compiled pattern. This facility is for testing
336           the  feature  in PCRE that allows it to execute patterns that were com-
337           piled on a host with a different endianness. This feature is not avail-
338           able  when the POSIX interface to PCRE is being used, that is, when the
339           /P pattern modifier is specified. See also the section about saving and
340           reloading compiled patterns below.
341    
342           The  /I  modifier  requests  that pcretest output information about the
343           compiled pattern (whether it is anchored, has a fixed first  character,
344           and so on). It does this by calling pcre[16]_fullinfo() after compiling
345           a pattern. If the pattern is studied, the results of that are also out-
346           put.
347    
348           The  /K modifier requests pcretest to show names from backtracking con-
349           trol verbs that are returned from calls to pcre[16]_exec().  It  causes
350           pcretest  to  create a pcre[16]_extra block if one has not already been
351           created by a call to pcre[16]_study(), and to set  the  PCRE_EXTRA_MARK
352           flag  and  the mark field within it, every time that pcre[16]_exec() is
353           called. If the variable that the mark field points to is non-NULL for a
354           match, non-match, or partial match, pcretest prints the string to which
355           it points. For a match, this is shown on a line by itself, tagged  with
356           "MK:". For a non-match it is added to the message.
357    
358           The  /L modifier must be followed directly by the name of a locale, for
359           example,
360    
361             /pattern/Lfr_FR
362    
363           For this reason, it must be the last modifier. The given locale is set,
364           pcre[16]_maketables()  is called to build a set of character tables for
365           the locale, and this is then passed to pcre[16]_compile() when  compil-
366           ing  the  regular  expression.  Without an /L (or /T) modifier, NULL is
367           passed as the tables pointer; that is, /L applies only to  the  expres-
368           sion on which it appears.
369    
370           The  /M  modifier  causes the size in bytes of the memory block used to
371           hold the compiled pattern to be output. This does not include the  size
372           of the pcre[16] block; it is just the actual compiled data. If the pat-
373           tern is successfully studied with  the  PCRE_STUDY_JIT_COMPILE  option,
374           the size of the JIT compiled code is also output.
375    
376           If  the  /S  modifier  appears  once,  it causes pcre[16]_study() to be
377           called after the expression has been compiled,  and  the  results  used
378           when  the  expression  is  matched.  If /S appears twice, it suppresses
379           studying, even if it was requested externally by the  -s  command  line
380           option.  This  makes  it  possible to specify that certain patterns are
381           always studied, and others are never studied, independently of -s. This
382           feature  is  used  in the test files in a few cases where the output is
383           different when the pattern is studied.
384    
385           If the /S modifier is immediately followed by a + character,  the  call
386           to  pcre[16]_study() is made with all the JIT study options, requesting
387           just-in-time optimization support if it is available, for  both  normal
388           and  partial matching. If you want to restrict the JIT compiling modes,
389           you can follow /S+ with a digit in the range 1 to 7:
390    
391             1  normal match only
392             2  soft partial match only
393             3  normal match and soft partial match
394             4  hard partial match only
395             6  soft and hard partial match
396             7  all three modes (default)
397    
398           If /S++ is used instead of /S+ (with or without a following digit), the
399           text  "(JIT)"  is  added  to  the first output line after a match or no
400           match when JIT-compiled code was actually used.
401    
402           Note that there is also an independent /+  modifier;  it  must  not  be
403           given immediately after /S or /S+ because this will be misinterpreted.
404    
405           If JIT studying is successful, the compiled JIT code will automatically
406           be used when pcre[16]_exec() is run, except when incompatible  run-time
407           options are specified. For more details, see the pcrejit documentation.
408           See also the \J escape sequence below for a way of setting the size  of
409           the JIT stack.
410    
411           The  /T  modifier  must be followed by a single digit. It causes a spe-
412           cific set of built-in character tables to be  passed  to  pcre[16]_com-
413           pile().  It  is used in the standard PCRE tests to check behaviour with
414           different character tables. The digit specifies the tables as follows:
415    
416             0   the default ASCII tables, as distributed in
417                   pcre_chartables.c.dist
418             1   a set of tables defining ISO 8859 characters
419    
420           In table 1, some characters whose codes are greater than 128 are  iden-
421           tified as letters, digits, spaces, etc.
422    
423       Using the POSIX wrapper API
424    
425           The  /P modifier causes pcretest to call PCRE via the POSIX wrapper API
426           rather than its native API. This supports only the 8-bit library.  When
427           /P  is set, the following modifiers set options for the regcomp() func-
428           tion:
429    
430             /i    REG_ICASE
431             /m    REG_NEWLINE
432             /N    REG_NOSUB
433             /s    REG_DOTALL     )
434             /U    REG_UNGREEDY   ) These options are not part of
435             /W    REG_UCP        )   the POSIX standard
436             /8    REG_UTF8       )
437    
438           The /+ modifier works as  described  above.  All  other  modifiers  are
439           ignored.
440    
441    
442    DATA LINES
443    
444           Before  each data line is passed to pcre[16]_exec(), leading and trail-
445           ing white space is removed, and it is then scanned for \ escapes.  Some
446           of  these  are pretty esoteric features, intended for checking out some
447           of the more complicated features of  PCRE.  If  you  are  just  testing
448           "ordinary"  regular  expressions, you probably don't need any of these.
449           The following escapes are recognized:
450    
451             \a         alarm (BEL, \x07)
452             \b         backspace (\x08)
453             \e         escape (\x27)
454             \f         form feed (\x0c)
455             \n         newline (\x0a)
456             \qdd       set the PCRE_MATCH_LIMIT limit to dd
457                          (any number of digits)
458             \r         carriage return (\x0d)
459             \t         tab (\x09)
460             \v         vertical tab (\x0b)
461             \nnn       octal character (up to 3 octal digits); always
462                          a byte unless > 255 in UTF-8 or 16-bit mode
463             \xhh       hexadecimal byte (up to 2 hex digits)
464             \x{hh...}  hexadecimal character (any number of hex digits)
465             \A         pass the PCRE_ANCHORED option to pcre[16]_exec()
466                          or pcre[16]_dfa_exec()
467             \B         pass the PCRE_NOTBOL option to pcre[16]_exec()
468                          or pcre[16]_dfa_exec()
469             \Cdd       call pcre[16]_copy_substring() for substring dd
470                          after a successful match (number less than 32)
471             \Cname     call pcre[16]_copy_named_substring() for substring
472                          "name" after a successful match (name termin-
473                          ated by next non alphanumeric character)
474             \C+        show the current captured substrings at callout
475                          time
476             \C-        do not supply a callout function
477             \C!n       return 1 instead of 0 when callout number n is
478                          reached
479             \C!n!m     return 1 instead of 0 when callout number n is
480                          reached for the nth time
481             \C*n       pass the number n (may be negative) as callout
482                          data; this is used as the callout return value
483             \D         use the pcre[16]_dfa_exec() match function
484             \F         only shortest match for pcre[16]_dfa_exec()
485             \Gdd       call pcre[16]_get_substring() for substring dd
486                          after a successful match (number less than 32)
487             \Gname     call pcre[16]_get_named_substring() for substring
488                          "name" after a successful match (name termin-
489                          ated by next non-alphanumeric character)
490             \Jdd       set up a JIT stack of dd kilobytes maximum (any
491                          number of digits)
492             \L         call pcre[16]_get_substringlist() after a
493                          successful match
494             \M         discover the minimum MATCH_LIMIT and
495                          MATCH_LIMIT_RECURSION settings
496             \N         pass the PCRE_NOTEMPTY option to pcre[16]_exec()
497                          or pcre[16]_dfa_exec(); if used twice, pass the
498                          PCRE_NOTEMPTY_ATSTART option
499             \Odd       set the size of the output vector passed to
500                          pcre[16]_exec() to dd (any number of digits)
501             \P         pass the PCRE_PARTIAL_SOFT option to pcre[16]_exec()
502                          or pcre[16]_dfa_exec(); if used twice, pass the
503                          PCRE_PARTIAL_HARD option
504             \Qdd       set the PCRE_MATCH_LIMIT_RECURSION limit to dd
505                          (any number of digits)
506             \R         pass the PCRE_DFA_RESTART option to pcre[16]_dfa_exec()
507             \S         output details of memory get/free calls during matching
508             \Y         pass the PCRE_NO_START_OPTIMIZE option to pcre[16]_exec()
509                          or pcre[16]_dfa_exec()
510             \Z         pass the PCRE_NOTEOL option to pcre[16]_exec()
511                          or pcre[16]_dfa_exec()
512             \?         pass the PCRE_NO_UTF[8|16]_CHECK option to
513                          pcre[16]_exec() or pcre[16]_dfa_exec()
514             \>dd       start the match at offset dd (optional "-"; then
515                          any number of digits); this sets the startoffset
516                          argument for pcre[16]_exec() or pcre[16]_dfa_exec()
517             \<cr>      pass the PCRE_NEWLINE_CR option to pcre[16]_exec()
518                          or pcre[16]_dfa_exec()
519             \<lf>      pass the PCRE_NEWLINE_LF option to pcre[16]_exec()
520                          or pcre[16]_dfa_exec()
521             \<crlf>    pass the PCRE_NEWLINE_CRLF option to pcre[16]_exec()
522                          or pcre[16]_dfa_exec()
523             \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre[16]_exec()
524                          or pcre[16]_dfa_exec()
525             \<any>     pass the PCRE_NEWLINE_ANY option to pcre[16]_exec()
526                          or pcre[16]_dfa_exec()
527    
528           The use of \x{hh...} is not dependent on the use of the /8 modifier  on
529           the  pattern. It is recognized always. There may be any number of hexa-
530           decimal digits inside the braces; invalid  values  provoke  error  mes-
531           sages.
532    
533           Note  that  \xhh  specifies one byte rather than one character in UTF-8
534           mode; this makes it possible to construct invalid UTF-8  sequences  for
535           testing  purposes.  On the other hand, \x{hh} is interpreted as a UTF-8
536           character in UTF-8 mode, generating more than one byte if the value  is
537           greater  than  127.   When testing the 8-bit library not in UTF-8 mode,
538           \x{hh} generates one byte for values less than 256, and causes an error
539           for greater values.
540    
541           In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
542           possible to construct invalid UTF-16 sequences for testing purposes.
543    
544           The escapes that specify line ending  sequences  are  literal  strings,
545           exactly as shown. No more than one newline setting should be present in
546           any data line.
547    
548           A backslash followed by anything else just escapes the  anything  else.
549           If  the very last character is a backslash, it is ignored. This gives a
550           way of passing an empty line as data, since a real  empty  line  termi-
551           nates the data input.
552    
553           The  \J escape provides a way of setting the maximum stack size that is
554           used by the just-in-time optimization code. It is ignored if JIT  opti-
555           mization  is  not being used. Providing a stack that is larger than the
556           default 32K is necessary only for very complicated patterns.
557    
558           If \M is present, pcretest calls pcre[16]_exec()  several  times,  with
559           different values in the match_limit and match_limit_recursion fields of
560           the pcre[16]_extra data structure, until it finds the  minimum  numbers
561           for  each  parameter  that  allow  pcre[16]_exec()  to complete without
562           error. Because this is testing a specific feature of the normal  inter-
563           pretive pcre[16]_exec() execution, the use of any JIT optimization that
564           might have been set up by the /S+ qualifier of -s+ option is disabled.
565    
566           The match_limit number is a measure of the amount of backtracking  that
567           takes  place,  and  checking it out can be instructive. For most simple
568           matches, the number is quite small, but for patterns  with  very  large
569           numbers  of  matching  possibilities,  it can become large very quickly
570           with increasing length of  subject  string.  The  match_limit_recursion
571           number  is  a  measure  of how much stack (or, if PCRE is compiled with
572           NO_RECURSE, how much heap) memory  is  needed  to  complete  the  match
573           attempt.
574    
575           When  \O  is  used, the value specified may be higher or lower than the
576           size set by the -O command line option (or defaulted to 45); \O applies
577           only to the call of pcre[16]_exec() for the line in which it appears.
578    
579           If  the /P modifier was present on the pattern, causing the POSIX wrap-
580           per API to be used, the only option-setting  sequences  that  have  any
581           effect  are  \B,  \N,  and  \Z,  causing  REG_NOTBOL, REG_NOTEMPTY, and
582           REG_NOTEOL, respectively, to be passed to regexec().
583    
584    
585    THE ALTERNATIVE MATCHING FUNCTION
586    
587           By  default,  pcretest  uses  the  standard  PCRE  matching   function,
588           pcre[16]_exec() to match each data line. PCRE also supports an alterna-
589           tive matching function, pcre[16]_dfa_test(), which operates in  a  dif-
590           ferent  way, and has some restrictions. The differences between the two
591           functions are described in the pcrematching documentation.
592    
593           If a data line contains the \D escape sequence, or if the command  line
594           contains  the  -dfa  option, the alternative matching function is used.
595           This function finds all possible matches at a given point. If, however,
596           the  \F escape sequence is present in the data line, it stops after the
597           first match is found. This is always the shortest possible match.
598    
599    
600    DEFAULT OUTPUT FROM PCRETEST
601    
602           This section describes the output when the  normal  matching  function,
603           pcre[16]_exec(), is being used.
604    
605           When a match succeeds, pcretest outputs the list of captured substrings
606           that pcre[16]_exec() returns, starting with number  0  for  the  string
607           that  matched  the whole pattern. Otherwise, it outputs "No match" when
608           the return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by  the
609           partially    matching    substring    when    pcre[16]_exec()   returns
610           PCRE_ERROR_PARTIAL. (Note that this is the entire  substring  that  was
611           inspected  during  the  partial match; it may include characters before
612           the actual match start if a lookbehind assertion, \K,  \b,  or  \B  was
613           involved.)  For  any  other  return, pcretest outputs the PCRE negative
614           error number and a short descriptive phrase. If the error is  a  failed
615           UTF  string check, the offset of the start of the failing character and
616           the reason code are also output, provided that the size of  the  output
617           vector  is  at least two. Here is an example of an interactive pcretest
618           run.
619    
620             $ pcretest
621             PCRE version 8.13 2011-04-30
622    
623               re> /^abc(\d+)/
624             data> abc123
625              0: abc123
626              1: 123
627             data> xyz
628             No match
629    
630           Unset capturing substrings that are not followed by one that is set are
631           not  returned by pcre[16]_exec(), and are not shown by pcretest. In the
632           following example, there are two capturing  substrings,  but  when  the
633           first  data  line is matched, the second, unset substring is not shown.
634           An "internal" unset substring is shown as "<unset>", as for the  second
635           data line.
636    
637               re> /(a)|(b)/
638             data> a
639              0: a
640              1: a
641             data> b
642              0: b
643              1: <unset>
644              2: b
645    
646           If  the strings contain any non-printing characters, they are output as
647           \xhh escapes if the value is less than 256 and UTF  mode  is  not  set.
648           Otherwise they are output as \x{hh...} escapes. See below for the defi-
649           nition of non-printing characters. If the pattern has the /+  modifier,
650           the  output  for substring 0 is followed by the the rest of the subject
651           string, identified by "0+" like this:
652    
653               re> /cat/+
654             data> cataract
655              0: cat
656              0+ aract
657    
658           If the pattern has the /g or /G modifier,  the  results  of  successive
659           matching attempts are output in sequence, like this:
660    
661               re> /\Bi(\w\w)/g
662             data> Mississippi
663              0: iss
664              1: ss
665              0: iss
666              1: ss
667              0: ipp
668              1: pp
669    
670           "No  match" is output only if the first match attempt fails. Here is an
671           example of a failure message (the offset 4 that is specified by \>4  is
672           past the end of the subject string):
673    
674               re> /xyz/
675             data> xyz\>4
676             Error -24 (bad offset value)
677    
678           If  any  of the sequences \C, \G, or \L are present in a data line that
679           is successfully matched, the substrings extracted  by  the  convenience
680           functions are output with C, G, or L after the string number instead of
681           a colon. This is in addition to the normal full list. The string length
682           (that  is,  the return from the extraction function) is given in paren-
683           theses after each string for \C and \G.
684    
685           Note that whereas patterns can be continued over several lines (a plain
686           ">" prompt is used for continuations), data lines may not. However new-
687           lines can be included in data by means of the \n escape (or  \r,  \r\n,
688           etc., depending on the newline sequence setting).
689    
690    
691    OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION
692    
693           When  the  alternative  matching function, pcre[16]_dfa_exec(), is used
694           (by means of the \D escape sequence or the -dfa command  line  option),
695           the  output  consists  of  a  list of all the matches that start at the
696           first point in the subject where there is at least one match. For exam-
697           ple:
698    
699               re> /(tang|tangerine|tan)/
700             data> yellow tangerine\D
701              0: tangerine
702              1: tang
703              2: tan
704    
705           (Using  the  normal  matching function on this data finds only "tang".)
706           The longest matching string is always given first (and numbered  zero).
707           After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol-
708           lowed by the partially matching  substring.  (Note  that  this  is  the
709           entire  substring  that  was inspected during the partial match; it may
710           include characters before the actual match start if a lookbehind asser-
711           tion, \K, \b, or \B was involved.)
712    
713           If /g is present on the pattern, the search for further matches resumes
714           at the end of the longest match. For example:
715    
716               re> /(tang|tangerine|tan)/g
717             data> yellow tangerine and tangy sultana\D
718              0: tangerine
719              1: tang
720              2: tan
721              0: tang
722              1: tan
723              0: tan
724    
725           Since the matching function does not  support  substring  capture,  the
726           escape  sequences  that  are concerned with captured substrings are not
727           relevant.
728    
729    
730    RESTARTING AFTER A PARTIAL MATCH
731    
732           When the alternative matching function has given the PCRE_ERROR_PARTIAL
733           return,  indicating that the subject partially matched the pattern, you
734           can restart the match with additional subject data by means of  the  \R
735           escape sequence. For example:
736    
737               re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/
738             data> 23ja\P\D
739             Partial match: 23ja
740             data> n05\R\D
741              0: n05
742    
743           For  further  information  about  partial matching, see the pcrepartial
744           documentation.
745    
746    
747  CALLOUTS  CALLOUTS
748    
749       If the pattern contains  any  callout  requests,  pcretest's         If the pattern contains any callout requests, pcretest's callout  func-
750       callout function will be called. By default, it displays the         tion  is  called  during  matching. This works with both matching func-
751       callout number, and the start and current positions  in  the         tions. By default, the called function displays the callout number, the
752       text at the callout time. For example, the output         start  and  current  positions in the text at the callout time, and the
753           next pattern item to be tested. For example:
754         --->pqrabcdef  
755           0    ^  ^           --->pqrabcdef
756               0    ^  ^     \d
757       indicates that callout number 0 occurred for a match attempt  
758       starting at the fourth character of the subject string, when         This output indicates that  callout  number  0  occurred  for  a  match
759       the pointer was at the seventh character. The callout  func-         attempt  starting  at  the fourth character of the subject string, when
760       tion returns zero (carry on matching) by default.         the pointer was at the seventh character of the data, and when the next
761           pattern  item  was  \d.  Just one circumflex is output if the start and
762       Inserting callouts may be helpful  when  using  pcretest  to         current positions are the same.
763       check  complicated regular expressions. For further informa-  
764       tion about callouts, see the pcrecallout documentation.         Callouts numbered 255 are assumed to be automatic callouts, inserted as
765           a  result  of the /C pattern modifier. In this case, instead of showing
766       For testing the PCRE library, additional control of  callout         the callout number, the offset in the pattern, preceded by a  plus,  is
767       behaviour  is available via escape sequences in the data, as         output. For example:
768       described in the following section.  In  particular,  it  is  
769       possible to pass in a number as callout data (the default is             re> /\d?[A-E]\*/C
770       zero). If the callout function receives a  non-zero  number,           data> E*
771       it returns that value instead of zero.           --->E*
772              +0 ^      \d?
773              +3 ^      [A-E]
774              +8 ^^     \*
775             +10 ^ ^
776              0: E*
777    
778           If a pattern contains (*MARK) items, an additional line is output when-
779           ever a change of latest mark is passed to  the  callout  function.  For
780           example:
781    
782               re> /a(*MARK:X)bc/C
783             data> abc
784             --->abc
785              +0 ^       a
786              +1 ^^      (*MARK:X)
787             +10 ^^      b
788             Latest Mark: X
789             +11 ^ ^     c
790             +12 ^  ^
791              0: abc
792    
793           The  mark  changes between matching "a" and "b", but stays the same for
794           the rest of the match, so nothing more is output. If, as  a  result  of
795           backtracking,  the  mark  reverts to being unset, the text "<unset>" is
796           output.
797    
798           The callout function in pcretest returns zero (carry  on  matching)  by
799           default,  but you can use a \C item in a data line (as described above)
800           to change this and other parameters of the callout.
801    
802           Inserting callouts can be helpful when using pcretest to check  compli-
803           cated  regular expressions. For further information about callouts, see
804           the pcrecallout documentation.
805    
806    
807    NON-PRINTING CHARACTERS
808    
809           When pcretest is outputting text in the compiled version of a  pattern,
810           bytes  other  than 32-126 are always treated as non-printing characters
811           are are therefore shown as hex escapes.
812    
813           When pcretest is outputting text that is a matched part  of  a  subject
814           string,  it behaves in the same way, unless a different locale has been
815           set for the  pattern  (using  the  /L  modifier).  In  this  case,  the
816           isprint() function to distinguish printing and non-printing characters.
817    
818    
819    SAVING AND RELOADING COMPILED PATTERNS
820    
821           The  facilities  described  in  this section are not available when the
822           POSIX interface to PCRE is being used, that is,  when  the  /P  pattern
823           modifier is specified.
824    
825           When the POSIX interface is not in use, you can cause pcretest to write
826           a compiled pattern to a file, by following the modifiers with >  and  a
827           file name.  For example:
828    
829             /pattern/im >/some/file
830    
831           See  the pcreprecompile documentation for a discussion about saving and
832           re-using compiled patterns.  Note that if the pattern was  successfully
833           studied with JIT optimization, the JIT data cannot be saved.
834    
835           The  data  that  is  written  is  binary. The first eight bytes are the
836           length of the compiled pattern data  followed  by  the  length  of  the
837           optional  study  data,  each  written as four bytes in big-endian order
838           (most significant byte first). If there is no study  data  (either  the
839           pattern was not studied, or studying did not return any data), the sec-
840           ond length is zero. The lengths are followed by an exact  copy  of  the
841           compiled  pattern.  If  there is additional study data, this (excluding
842           any JIT data) follows immediately after  the  compiled  pattern.  After
843           writing the file, pcretest expects to read a new pattern.
844    
845           A  saved  pattern  can  be reloaded into pcretest by specifying < and a
846           file name instead of a pattern. The name of the file must not contain a
847           < character, as otherwise pcretest will interpret the line as a pattern
848           delimited by < characters.  For example:
849    
850              re> </some/file
851             Compiled pattern loaded from /some/file
852             No study data
853    
854           If the pattern was previously studied with the  JIT  optimization,  the
855           JIT  information cannot be saved and restored, and so is lost. When the
856           pattern has been loaded, pcretest proceeds to read data  lines  in  the
857           usual way.
858    
859           You  can copy a file written by pcretest to a different host and reload
860           it there, even if the new host has opposite endianness to  the  one  on
861           which  the pattern was compiled. For example, you can compile on an i86
862           machine and run on a SPARC machine. When a pattern  is  reloaded  on  a
863           host with different endianness, the confirmation message is changed to:
864    
865             Compiled pattern (byte-inverted) loaded from /some/file
866    
867           The test suite contains some saved pre-compiled patterns with different
868           endianness. These are reloaded using "<!" instead  of  just  "<".  This
869           suppresses the "(byte-inverted)" text so that the output is the same on
870           all hosts. It also forces debugging output once the  pattern  has  been
871           reloaded.
872    
873           File  names  for  saving and reloading can be absolute or relative, but
874           note that the shell facility of expanding a file name that starts  with
875           a tilde (~) is not available.
876    
877           The  ability to save and reload files in pcretest is intended for test-
878           ing and experimentation. It is not intended for production use  because
879           only  a  single pattern can be written to a file. Furthermore, there is
880           no facility for supplying  custom  character  tables  for  use  with  a
881           reloaded  pattern.  If  the  original  pattern was compiled with custom
882           tables, an attempt to match a subject string using a  reloaded  pattern
883           is  likely to cause pcretest to crash.  Finally, if you attempt to load
884           a file that is not in the correct format, the result is undefined.
885    
886    
887  DATA LINES  SEE ALSO
888    
889       Before each data line is passed to pcre_exec(), leading  and         pcre(3), pcre16(3),  pcreapi(3),  pcrecallout(3),  pcrejit,  pcrematch-
890       trailing whitespace is removed, and it is then scanned for \         ing(3), pcrepartial(d), 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.  
891    
892    
893  AUTHOR  AUTHOR
894    
895       Philip Hazel <ph10@cam.ac.uk>         Philip Hazel
896       University Computing Service,         University Computing Service
897       Cambridge CB2 3QG, England.         Cambridge CB2 3QH, England.
898    
899    
900    REVISION
901    
902  Last updated: 20 August 2003         Last updated: 21 February 2012
903  Copyright (c) 1997-2003 University of Cambridge.         Copyright (c) 1997-2012 University of Cambridge.

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