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1  README file for PCRE (Perl-compatible regular expressions)  README file for PCRE (Perl-compatible regular expression library)
2  ----------------------------------------------------------  -----------------------------------------------------------------
3    
4  *******************************************************************************  The latest release of PCRE is always available from
 *           IMPORTANT FOR THOSE UPGRADING FROM VERSIONS BEFORE 2.00           *  
 *                                                                             *  
 * Please note that there has been a change in the API such that a larger      *  
 * ovector is required at matching time, to provide some additional workspace. *  
 * The new man page has details. This change was necessary in order to support *  
 * some of the new functionality in Perl 5.005.                                *  
 *                                                                             *  
 *           IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.00                   *  
 *                                                                             *  
 * Another (I hope this is the last!) change has been made to the API for the  *  
 * pcre_compile() function. An additional argument has been added to make it   *  
 * possible to pass over a pointer to character tables built in the current    *  
 * locale by pcre_maketables(). To use the default tables, this new arguement  *  
 * should be passed as NULL.                                                   *  
 *                                                                             *  
 *           IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.05                   *  
 *                                                                             *  
 * Yet another (and again I hope this really is the last) change has been made *  
 * to the API for the pcre_exec() function. An additional argument has been    *  
 * added to make it possible to start the match other than at the start of the *  
 * subject string. This is important if there are lookbehinds. The new man     *  
 * page has the details, but you just want to convert existing programs, all   *  
 * you need to do is to stick in a new fifth argument to pcre_exec(), with a   *  
 * value of zero. For example, change                                          *  
 *                                                                             *  
 *   pcre_exec(pattern, extra, subject, length, options, ovec, ovecsize)       *  
 * to                                                                          *  
 *   pcre_exec(pattern, extra, subject, length, 0, options, ovec, ovecsize)    *  
 *******************************************************************************  
5    
6      ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.tar.gz
7    
8  The distribution should contain the following files:  Please read the NEWS file if you are upgrading from a previous release.
9    
10    PCRE has its own native API, but a set of "wrapper" functions that are based on
11    the POSIX API are also supplied in the library libpcreposix. Note that this
12    just provides a POSIX calling interface to PCRE: the regular expressions
13    themselves still follow Perl syntax and semantics. The header file
14    for the POSIX-style functions is called pcreposix.h. The official POSIX name is
15    regex.h, but I didn't want to risk possible problems with existing files of
16    that name by distributing it that way. To use it with an existing program that
17    uses the POSIX API, it will have to be renamed or pointed at by a link.
18    
19    
20    Contributions by users of PCRE
21    ------------------------------
22    
23    You can find contributions from PCRE users in the directory
24    
25      ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/Contrib
26    
27    where there is also a README file giving brief descriptions of what they are.
28    Several of them provide support for compiling PCRE on various flavours of
29    Windows systems (I myself do not use Windows). Some are complete in themselves;
30    others are pointers to URLs containing relevant files.
31    
32    
33    Building PCRE on a Unix-like system
34    -----------------------------------
35    
36    To build PCRE on a Unix-like system, first run the "configure" command from the
37    PCRE distribution directory, with your current directory set to the directory
38    where you want the files to be created. This command is a standard GNU
39    "autoconf" configuration script, for which generic instructions are supplied in
40    INSTALL.
41    
42    Most commonly, people build PCRE within its own distribution directory, and in
43    this case, on many systems, just running "./configure" is sufficient, but the
44    usual methods of changing standard defaults are available. For example,
45    
46    CFLAGS='-O2 -Wall' ./configure --prefix=/opt/local
47    
48    specifies that the C compiler should be run with the flags '-O2 -Wall' instead
49    of the default, and that "make install" should install PCRE under /opt/local
50    instead of the default /usr/local.
51    
52    If you want to build in a different directory, just run "configure" with that
53    directory as current. For example, suppose you have unpacked the PCRE source
54    into /source/pcre/pcre-xxx, but you want to build it in /build/pcre/pcre-xxx:
55    
56    cd /build/pcre/pcre-xxx
57    /source/pcre/pcre-xxx/configure
58    
59    There are some optional features that can be included or omitted from the PCRE
60    library. You can read more about them in the pcrebuild man page.
61    
62    . If you want to make use of the support for UTF-8 character strings in PCRE,
63      you must add --enable-utf8 to the "configure" command. Without it, the code
64      for handling UTF-8 is not included in the library. (Even when included, it
65      still has to be enabled by an option at run time.)
66    
67    . You can build PCRE to recognized CR or NL as the newline character, instead
68      of whatever your compiler uses for "\n", by adding --newline-is-cr or
69      --newline-is-nl to the "configure" command, respectively. Only do this if you
70      really understand what you are doing. On traditional Unix-like systems, the
71      newline character is NL.
72    
73    . When called via the POSIX interface, PCRE uses malloc() to get additional
74      storage for processing capturing parentheses if there are more than 10 of
75      them. You can increase this threshold by setting, for example,
76    
77      --with-posix-malloc-threshold=20
78    
79      on the "configure" command.
80    
81    . PCRE has a counter which can be set to limit the amount of resources it uses.
82      If the limit is exceeded during a match, the match fails. The default is ten
83      million. You can change the default by setting, for example,
84    
85      --with-match-limit=500000
86    
87      on the "configure" command. This is just the default; individual calls to
88      pcre_exec() can supply their own value. There is discussion on the pcreapi
89      man page.
90    
91    . The default maximum compiled pattern size is around 64K. You can increase
92      this by adding --with-link-size=3 to the "configure" command. You can
93      increase it even more by setting --with-link-size=4, but this is unlikely
94      ever to be necessary. If you build PCRE with an increased link size, test 2
95      (and 5 if you are using UTF-8) will fail. Part of the output of these tests
96      is a representation of the compiled pattern, and this changes with the link
97      size.
98    
99    The "configure" script builds five files:
100    
101    . libtool is a script that builds shared and/or static libraries
102    . Makefile is built by copying Makefile.in and making substitutions.
103    . config.h is built by copying config.in and making substitutions.
104    . pcre-config is built by copying pcre-config.in and making substitutions.
105    . RunTest is a script for running tests
106    
107    Once "configure" has run, you can run "make". It builds two libraries called
108    libpcre and libpcreposix, a test program called pcretest, and the pcregrep
109    command. You can use "make install" to copy these, the public header files
110    pcre.h and pcreposix.h, and the man pages to appropriate live directories on
111    your system, in the normal way.
112    
113    Running "make install" also installs the command pcre-config, which can be used
114    to recall information about the PCRE configuration and installation. For
115    example,
116    
117    ChangeLog         log of changes to the code    pcre-config --version
   LICENCE           conditions for the use of PCRE  
   Makefile          for building PCRE in Unix systems  
   README            this file  
   RunTest           a Unix shell script for running tests  
   Tech.Notes        notes on the encoding  
   pcre.3            man page source for the functions  
   pcre.3.txt        plain text version  
   pcre.3.html       HTML version  
   pcreposix.3       man page source for the POSIX wrapper API  
   pcreposix.3.txt   plain text version  
   pcreposix.3.HTML  HTML version  
   dftables.c        auxiliary program for building chartables.c  
   get.c             )  
   maketables.c      )  
   study.c           ) source of  
   pcre.c            )   the functions  
   pcreposix.c       )  
   pcre.h            header for the external API  
   pcreposix.h       header for the external POSIX wrapper API  
   internal.h        header for internal use  
   pcretest.c        test program  
   pgrep.1           man page source for pgrep  
   pgrep.1.txt       plain text version  
   pgrep.1.HTML      HTML version  
   pgrep.c           source of a grep utility that uses PCRE  
   perltest          Perl test program  
   testinput1        test data, compatible with Perl 5.004 and 5.005  
   testinput2        test data for error messages and non-Perl things  
   testinput3        test data, compatible with Perl 5.005  
   testinput4        test data for locale-specific tests  
   testoutput1       test results corresponding to testinput1  
   testoutput2       test results corresponding to testinput2  
   testoutput3       test results corresponding to testinput3  
   testoutput4       test results corresponding to testinput4  
   dll.mk            for Win32 DLL  
   pcre.def          ditto  
   
 To build PCRE on a Unix system, first edit Makefile for your system. It is a  
 fairly simple make file, and there are some comments near the top, after the  
 text "On a Unix system". Then run "make". It builds two libraries called  
 libpcre.a and libpcreposix.a, a test program called pcretest, and the pgrep  
 command. You can use "make install" to copy these, and the public header file  
 pcre.h, to appropriate live directories on your system. These installation  
 directories are defined at the top of the Makefile, and you should edit them if  
 necessary.  
   
 For a non-Unix system, read the comments at the top of Makefile, which give  
 some hints on what needs to be done. PCRE has been compiled on Windows systems  
 and on Macintoshes, but I don't know the details as I don't use those systems.  
 It should be straightforward to build PCRE on any system that has a Standard C  
 compiler.  
   
 Some help in building a Win32 DLL of PCRE in GnuWin32 environments was  
 contributed by Paul.Sokolovsky@technologist.com. These environments are  
 Mingw32 (http://www.xraylith.wisc.edu/~khan/software/gnu-win32/) and  
 CygWin  (http://sourceware.cygnus.com/cygwin/). Paul comments:  
   
   For CygWin, set CFLAGS=-mno-cygwin, and do 'make dll'. You'll get  
   pcre.dll (containing pcreposix also), libpcre.dll.a, and dynamically  
   linked pgrep and pcretest. If you have /bin/sh, run RunTest (three  
   main test go ok, locale not supported).  
   
 To test PCRE, run the RunTest script in the pcre directory. This can also be  
 run by "make runtest". It runs the pcretest test program (which is documented  
 below) on each of the testinput files in turn, and compares the output with the  
 contents of the corresponding testoutput file. A file called testtry is used to  
 hold the output from pcretest. To run pcretest on just one of the test files,  
 give its number as an argument to RunTest, for example:  
   
   RunTest 3  
   
 The first and third test files can also be fed directly into the perltest  
 script to check that Perl gives the same results. The third file requires the  
 additional features of release 5.005, which is why it is kept separate from the  
 main test input, which needs only Perl 5.004. In the long run, when 5.005 is  
 widespread, these two test files may get amalgamated.  
   
 The second set of tests check pcre_info(), pcre_study(), pcre_copy_substring(),  
 pcre_get_substring(), pcre_get_substring_list(), error detection and run-time  
 flags that are specific to PCRE, as well as the POSIX wrapper API.  
118    
119  The fourth set of tests checks pcre_maketables(), the facility for building a  prints the version number, and
120    
121     pcre-config --libs
122    
123    outputs information about where the library is installed. This command can be
124    included in makefiles for programs that use PCRE, saving the programmer from
125    having to remember too many details.
126    
127    
128    Shared libraries on Unix-like systems
129    -------------------------------------
130    
131    The default distribution builds PCRE as two shared libraries and two static
132    libraries, as long as the operating system supports shared libraries. Shared
133    library support relies on the "libtool" script which is built as part of the
134    "configure" process.
135    
136    The libtool script is used to compile and link both shared and static
137    libraries. They are placed in a subdirectory called .libs when they are newly
138    built. The programs pcretest and pcregrep are built to use these uninstalled
139    libraries (by means of wrapper scripts in the case of shared libraries). When
140    you use "make install" to install shared libraries, pcregrep and pcretest are
141    automatically re-built to use the newly installed shared libraries before being
142    installed themselves. However, the versions left in the source directory still
143    use the uninstalled libraries.
144    
145    To build PCRE using static libraries only you must use --disable-shared when
146    configuring it. For example
147    
148    ./configure --prefix=/usr/gnu --disable-shared
149    
150    Then run "make" in the usual way. Similarly, you can use --disable-static to
151    build only shared libraries.
152    
153    
154    Cross-compiling on a Unix-like system
155    -------------------------------------
156    
157    You can specify CC and CFLAGS in the normal way to the "configure" command, in
158    order to cross-compile PCRE for some other host. However, during the building
159    process, the dftables.c source file is compiled *and run* on the local host, in
160    order to generate the default character tables (the chartables.c file). It
161    therefore needs to be compiled with the local compiler, not the cross compiler.
162    You can do this by specifying HOST_CC (and if necessary HOST_CFLAGS) when
163    calling the "configure" command. If they are not specified, they default to the
164    values of CC and CFLAGS.
165    
166    
167    Building on non-Unix systems
168    ----------------------------
169    
170    For a non-Unix system, read the comments in the file NON-UNIX-USE. PCRE has
171    been compiled on Windows systems and on Macintoshes, but I don't know the
172    details because I don't use those systems. It should be straightforward to
173    build PCRE on any system that has a Standard C compiler, because it uses only
174    Standard C functions.
175    
176    
177    Testing PCRE
178    ------------
179    
180    To test PCRE on a Unix system, run the RunTest script that is created by the
181    configuring process. (This can also be run by "make runtest", "make check", or
182    "make test".) For other systems, see the instruction in NON-UNIX-USE.
183    
184    The script runs the pcretest test program (which is documented in its own man
185    page) on each of the testinput files (in the testdata directory) in turn,
186    and compares the output with the contents of the corresponding testoutput file.
187    A file called testtry is used to hold the output from pcretest. To run pcretest
188    on just one of the test files, give its number as an argument to RunTest, for
189    example:
190    
191      RunTest 2
192    
193    The first file can also be fed directly into the perltest script to check that
194    Perl gives the same results. The only difference you should see is in the first
195    few lines, where the Perl version is given instead of the PCRE version.
196    
197    The second set of tests check pcre_fullinfo(), pcre_info(), pcre_study(),
198    pcre_copy_substring(), pcre_get_substring(), pcre_get_substring_list(), error
199    detection, and run-time flags that are specific to PCRE, as well as the POSIX
200    wrapper API. It also uses the debugging flag to check some of the internals of
201    pcre_compile().
202    
203    If you build PCRE with a locale setting that is not the standard C locale, the
204    character tables may be different (see next paragraph). In some cases, this may
205    cause failures in the second set of tests. For example, in a locale where the
206    isprint() function yields TRUE for characters in the range 128-255, the use of
207    [:isascii:] inside a character class defines a different set of characters, and
208    this shows up in this test as a difference in the compiled code, which is being
209    listed for checking. Where the comparison test output contains [\x00-\x7f] the
210    test will contain [\x00-\xff], and similarly in some other cases. This is not a
211    bug in PCRE.
212    
213    The third set of tests checks pcre_maketables(), the facility for building a
214  set of character tables for a specific locale and using them instead of the  set of character tables for a specific locale and using them instead of the
215  default tables. The tests make use of the "fr" (French) locale. Before running  default tables. The tests make use of the "fr" (French) locale. Before running
216  the test, the script checks for the presence of this locale by running the  the test, the script checks for the presence of this locale by running the
217  "locale" command. If that command fails, or if it doesn't include "fr" in the  "locale" command. If that command fails, or if it doesn't include "fr" in the
218  list of available locales, the fourth test cannot be run, and a comment is  list of available locales, the third test cannot be run, and a comment is
219  output to say why. If running this test produces instances of the error  output to say why. If running this test produces instances of the error
220    
221    ** Failed to set locale "fr"    ** Failed to set locale "fr"
# Line 130  output to say why. If running this test Line 223  output to say why. If running this test
223  in the comparison output, it means that locale is not available on your system,  in the comparison output, it means that locale is not available on your system,
224  despite being listed by "locale". This does not mean that PCRE is broken.  despite being listed by "locale". This does not mean that PCRE is broken.
225    
226  PCRE has its own native API, but a set of "wrapper" functions that are based on  The fourth test checks the UTF-8 support. It is not run automatically unless
227  the POSIX API are also supplied in the library libpcreposix.a. Note that this  PCRE is built with UTF-8 support. To do this you must set --enable-utf8 when
228  just provides a POSIX calling interface to PCRE: the regular expressions  running "configure". This file can be also fed directly to the perltest script,
229  themselves still follow Perl syntax and semantics. The header file  provided you are running Perl 5.8 or higher. (For Perl 5.6, a small patch,
230  for the POSIX-style functions is called pcreposix.h. The official POSIX name is  commented in the script, can be be used.)
231  regex.h, but I didn't want to risk possible problems with existing files of  
232  that name by distributing it that way. To use it with an existing program that  The fifth and final file tests error handling with UTF-8 encoding, and internal
233  uses the POSIX API, it will have to be renamed or pointed at by a link.  UTF-8 features of PCRE that are not relevant to Perl.
234    
235    
236  Character tables  Character tables
# Line 179  You should not alter the set of characte Line 272  You should not alter the set of characte
272  will cause PCRE to malfunction.  will cause PCRE to malfunction.
273    
274    
275  The pcretest program  Manifest
276  --------------------  --------
   
 This program is intended for testing PCRE, but it can also be used for  
 experimenting with regular expressions.  
277    
278  If it is given two filename arguments, it reads from the first and writes to  The distribution should contain the following files:
 the second. If it is given only one filename argument, it reads from that file  
 and writes to stdout. Otherwise, it reads from stdin and writes to stdout, and  
 prompts for each line of input.  
   
 The program handles any number of sets of input on a single input file. Each  
 set starts with a regular expression, and continues with any number of data  
 lines to be matched against the pattern. An empty line signals the end of the  
 set. The regular expressions are given enclosed in any non-alphameric  
 delimiters other than backslash, for example  
   
   /(a|bc)x+yz/  
   
 White space before the initial delimiter is ignored. A regular expression may  
 be continued over several input lines, in which case the newline characters are  
 included within it. See the testinput files for many examples. It is possible  
 to include the delimiter within the pattern by escaping it, for example  
   
   /abc\/def/  
   
 If you do so, the escape and the delimiter form part of the pattern, but since  
 delimiters are always non-alphameric, this does not affect its interpretation.  
 If the terminating delimiter is immediately followed by a backslash, for  
 example,  
   
   /abc/\  
279    
280  then a backslash is added to the end of the pattern. This is done to provide a  (A) The actual source files of the PCRE library functions and their
281  way of testing the error condition that arises if a pattern finishes with a      headers:
 backslash, because  
282    
283    /abc\/    dftables.c            auxiliary program for building chartables.c
284      get.c                 )
285      maketables.c          )
286      study.c               ) source of
287      pcre.c                )   the functions
288      pcreposix.c           )
289      printint.c            )
290      pcre.in               "source" for the header for the external API; pcre.h
291                              is built from this by "configure"
292      pcreposix.h           header for the external POSIX wrapper API
293      internal.h            header for internal use
294      config.in             template for config.h, which is built by configure
295    
296    (B) Auxiliary files:
297    
298      AUTHORS               information about the author of PCRE
299      ChangeLog             log of changes to the code
300      INSTALL               generic installation instructions
301      LICENCE               conditions for the use of PCRE
302      COPYING               the same, using GNU's standard name
303      Makefile.in           template for Unix Makefile, which is built by configure
304      NEWS                  important changes in this release
305      NON-UNIX-USE          notes on building PCRE on non-Unix systems
306      README                this file
307      RunTest.in            template for a Unix shell script for running tests
308      config.guess          ) files used by libtool,
309      config.sub            )   used only when building a shared library
310      configure             a configuring shell script (built by autoconf)
311      configure.in          the autoconf input used to build configure
312      doc/Tech.Notes        notes on the encoding
313      doc/*.3               man page sources for the PCRE functions
314      doc/*.1               man page sources for pcregrep and pcretest
315      doc/html/*            HTML documentation
316      doc/pcre.txt          plain text version of the man pages
317      doc/pcretest.txt      plain text documentation of test program
318      doc/perltest.txt      plain text documentation of Perl test program
319      install-sh            a shell script for installing files
320      ltmain.sh             file used to build a libtool script
321      pcretest.c            comprehensive test program
322      pcredemo.c            simple demonstration of coding calls to PCRE
323      perltest              Perl test program
324      pcregrep.c            source of a grep utility that uses PCRE
325      pcre-config.in        source of script which retains PCRE information
326      testdata/testinput1   test data, compatible with Perl
327      testdata/testinput2   test data for error messages and non-Perl things
328      testdata/testinput3   test data for locale-specific tests
329      testdata/testinput4   test data for UTF-8 tests compatible with Perl
330      testdata/testinput5   test data for other UTF-8 tests
331      testdata/testoutput1  test results corresponding to testinput1
332      testdata/testoutput2  test results corresponding to testinput2
333      testdata/testoutput3  test results corresponding to testinput3
334      testdata/testoutput4  test results corresponding to testinput4
335      testdata/testoutput5  test results corresponding to testinput5
336    
337  is interpreted as the first line of a pattern that starts with "abc/", causing  (C) Auxiliary files for Win32 DLL
 pcretest to read the next line as a continuation of the regular expression.  
338    
339  The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,    dll.mk
340  PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For    pcre.def
 example:  
341    
342    /caseless/i  (D) Auxiliary file for VPASCAL
343    
344  These modifier letters have the same effect as they do in Perl. There are    makevp.bat
 others which set PCRE options that do not correspond to anything in Perl: /A,  
 /E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.  
   
 Searching for all possible matches within each subject string can be requested  
 by the /g or /G modifier. After finding a match, PCRE is called again to search  
 the remainder of the subject string. The difference between /g and /G is that  
 the former uses the startoffset argument to pcre_exec() to start searching at  
 a new point within the entire string (which is in effect what Perl does),  
 whereas the latter passes over a shortened substring. This makes a difference  
 to the matching process if the pattern begins with a lookbehind assertion  
 (including \b or \B).  
   
 If any call to pcre_exec() in a /g or /G sequence matches an empty string, the  
 next call is done with the PCRE_NOTEMPTY flag set so that it cannot match an  
 empty string again. This imitates the way Perl handles such cases when using  
 the /g modifier or the split() function.  
   
 There are a number of other modifiers for controlling the way pcretest  
 operates.  
   
 The /+ modifier requests that as well as outputting the substring that matched  
 the entire pattern, pcretest should in addition output the remainder of the  
 subject string. This is useful for tests where the subject contains multiple  
 copies of the same substring.  
   
 The /L modifier must be followed directly by the name of a locale, for example,  
   
   /pattern/Lfr  
   
 For this reason, it must be the last modifier letter. The given locale is set,  
 pcre_maketables() is called to build a set of character tables for the locale,  
 and this is then passed to pcre_compile() when compiling the regular  
 expression. Without an /L modifier, NULL is passed as the tables pointer; that  
 is, /L applies only to the expression on which it appears.  
   
 The /I modifier requests that pcretest output information about the compiled  
 expression (whether it is anchored, has a fixed first character, and so on). It  
 does this by calling pcre_info() after compiling an expression, and outputting  
 the information it gets back. If the pattern is studied, the results of that  
 are also output.  
   
 The /D modifier is a PCRE debugging feature, which also assumes /I. It causes  
 the internal form of compiled regular expressions to be output after  
 compilation.  
   
 The /S modifier causes pcre_study() to be called after the expression has been  
 compiled, and the results used when the expression is matched.  
   
 The /M modifier causes the size of memory block used to hold the compiled  
 pattern to be output.  
   
 Finally, the /P modifier causes pcretest to call PCRE via the POSIX wrapper API  
 rather than its native API. When this is done, all other modifiers except /i,  
 /m, and /+ are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is  
 set if /m is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always,  
 and PCRE_DOTALL unless REG_NEWLINE is set.  
   
 Before each data line is passed to pcre_exec(), leading and trailing whitespace  
 is removed, and it is then scanned for \ escapes. The following are recognized:  
   
   \a     alarm (= BEL)  
   \b     backspace  
   \e     escape  
   \f     formfeed  
   \n     newline  
   \r     carriage return  
   \t     tab  
   \v     vertical tab  
   \nnn   octal character (up to 3 octal digits)  
   \xhh   hexadecimal character (up to 2 hex digits)  
   
   \A     pass the PCRE_ANCHORED option to pcre_exec()  
   \B     pass the PCRE_NOTBOL option to pcre_exec()  
   \Cdd   call pcre_copy_substring() for substring dd after a successful match  
            (any decimal number less than 32)  
   \Gdd   call pcre_get_substring() for substring dd after a successful match  
            (any decimal number less than 32)  
   \L     call pcre_get_substringlist() after a successful match  
   \N     pass the PCRE_NOTEMPTY option to pcre_exec()  
   \Odd   set the size of the output vector passed to pcre_exec() to dd  
            (any number of decimal digits)  
   \Z     pass the PCRE_NOTEOL option to pcre_exec()  
   
 A backslash followed by anything else just escapes the anything else. If the  
 very last character is a backslash, it is ignored. This gives a way of passing  
 an empty line as data, since a real empty line terminates the data input.  
   
 If /P was present on the regex, causing the POSIX wrapper API to be used, only  
 \B, and \Z have any effect, causing REG_NOTBOL and REG_NOTEOL to be passed to  
 regexec() respectively.  
   
 When a match succeeds, pcretest outputs the list of captured substrings that  
 pcre_exec() returns, starting with number 0 for the string that matched the  
 whole pattern. Here is an example of an interactive pcretest run.  
   
   $ pcretest  
   PCRE version 2.06 08-Jun-1999  
   
     re> /^abc(\d+)/  
   data> abc123  
    0: abc123  
    1: 123  
   data> xyz  
   No match  
   
 If the strings contain any non-printing characters, they are output as \0x  
 escapes. If the pattern has the /+ modifier, then the output for substring 0 is  
 followed by the the rest of the subject string, identified by "0+" like this:  
   
     re> /cat/+  
   data> cataract  
    0: cat  
    0+ aract  
   
 If the pattern has the /g or /G modifier, the results of successive matching  
 attempts are output in sequence, like this:  
   
     re> /\Bi(\w\w)/g  
   data> Mississippi  
    0: iss  
    1: ss  
    0: iss  
    1: ss  
    0: ipp  
    1: pp  
   
 "No match" is output only if the first match attempt fails.  
   
 If any of \C, \G, or \L are present in a data line that is successfully  
 matched, the substrings extracted by the convenience functions are output with  
 C, G, or L after the string number instead of a colon. This is in addition to  
 the normal full list. The string length (that is, the return from the  
 extraction function) is given in parentheses after each string for \C and \G.  
   
 Note that while patterns can be continued over several lines (a plain ">"  
 prompt is used for continuations), data lines may not. However newlines can be  
 included in data by means of the \n escape.  
   
 If the -p option is given to pcretest, it is equivalent to adding /P to each  
 regular expression: the POSIX wrapper API is used to call PCRE. None of the  
 following flags has any effect in this case.  
   
 If the option -d is given to pcretest, it is equivalent to adding /D to each  
 regular expression: the internal form is output after compilation.  
   
 If the option -i is given to pcretest, it is equivalent to adding /I to each  
 regular expression: information about the compiled pattern is given after  
 compilation.  
   
 If the option -m is given to pcretest, it outputs the size of each compiled  
 pattern after it has been compiled. It is equivalent to adding /M to each  
 regular expression. For compatibility with earlier versions of pcretest, -s is  
 a synonym for -m.  
   
 If the -t option is given, each compile, study, and match is run 20000 times  
 while being timed, and the resulting time per compile or match is output in  
 milliseconds. Do not set -t with -s, because you will then get the size output  
 20000 times and the timing will be distorted. If you want to change the number  
 of repetitions used for timing, edit the definition of LOOPREPEAT at the top of  
 pcretest.c  
   
   
   
 The perltest program  
 --------------------  
   
 The perltest program tests Perl's regular expressions; it has the same  
 specification as pcretest, and so can be given identical input, except that  
 input patterns can be followed only by Perl's lower case modifiers. The  
 contents of testinput1 and testinput3 meet this condition.  
   
 The data lines are processed as Perl double-quoted strings, so if they contain  
 " \ $ or @ characters, these have to be escaped. For this reason, all such  
 characters in testinput1 and testinput3 are escaped so that they can be used  
 for perltest as well as for pcretest, and the special upper case modifiers such  
 as /A that pcretest recognizes are not used in these files. The output should  
 be identical, apart from the initial identifying banner.  
   
 The testinput2 and testinput4 files are not suitable for feeding to perltest,  
 since they do make use of the special upper case modifiers and escapes that  
 pcretest uses to test some features of PCRE. The first of these files also  
 contains malformed regular expressions, in order to check that PCRE diagnoses  
 them correctly.  
345    
346  Philip Hazel <ph10@cam.ac.uk>  Philip Hazel <ph10@cam.ac.uk>
347  July 1999  February 2003

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