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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.                                                   *  
 *******************************************************************************  
5    
6  The distribution should contain the following files:    ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.tar.gz
   
   ChangeLog         log of changes to the code  
   LICENCE           conditions for the use of PCRE  
   Makefile          for building PCRE  
   README            this file  
   RunTest           a shell script for running tests  
   Tech.Notes        notes on the encoding  
   pcre.3            man page for the functions  
   pcreposix.3       man page for the POSIX wrapper API  
   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 for pgrep  
   pgrep.c           source of a grep utility that uses PCRE  
   perltest          Perl test program  
   testinput         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  
   testoutput        test results corresponding to testinput  
   testoutput2       test results corresponding to testinput2  
   testoutput3       test results corresponding to testinput3  
   testoutput4       test results corresponding to testinput4  
   
 To build PCRE, edit Makefile for your system (it is a fairly simple make file,  
 and there are some comments at the top) and then run it. It builds two  
 libraries called libpcre.a and libpcreposix.a, a test program called pcretest,  
 and the pgrep command.  
   
 To test PCRE, run the RunTest script in the pcre directory. This runs pcretest  
 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 (which is documented below).  
   
 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  
 program 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.  
   
 The fourth set of tests checks pcre_maketables(), the facility for building a  
 set of character tables for a specific locale and using them instead of the  
 default tables. The tests make use of the "fr" (French) locale. Before running  
 the test, the script checks for the presence of this locale by running the  
 "locale" command. If that command fails, or if it doesn't include "fr" in the  
 list of available locales, the fourth test cannot be run, and a comment is  
 output to say why. If running this test produces instances of the error  
7    
8    ** Failed to set locale "fr"  Please read the NEWS file if you are upgrading from a previous release.
   
 in the comparison output, it means that locale is not available on your system,  
 despite being listed by "locale". This does not mean that PCRE is broken.  
   
 To install PCRE, copy libpcre.a to any suitable library directory (e.g.  
 /usr/local/lib), pcre.h to any suitable include directory (e.g.  
 /usr/local/include), and pcre.3 to any suitable man directory (e.g.  
 /usr/local/man/man3).  
   
 To install the pgrep command, copy it to any suitable binary directory, (e.g.  
 /usr/local/bin) and pgrep.1 to any suitable man directory (e.g.  
 /usr/local/man/man1).  
9    
10  PCRE has its own native API, but a set of "wrapper" functions that are based on  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.a. Note that this  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  just provides a POSIX calling interface to PCRE: the regular expressions
13  themselves still follow Perl syntax and semantics. The header file  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  for the POSIX-style functions is called pcreposix.h. The official POSIX name is
# Line 106  regex.h, but I didn't want to risk possi Line 16  regex.h, but I didn't want to risk possi
16  that name by distributing it that way. To use it with an existing program that  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.  uses the POSIX API, it will have to be renamed or pointed at by a link.
18    
19    If you are using the POSIX interface to PCRE and there is already a POSIX regex
20    library installed on your system, you must take care when linking programs to
21    ensure that they link with PCRE's libpcreposix library. Otherwise they may pick
22    up the "real" POSIX functions of the same name.
23    
24    
25    Documentation for PCRE
26    ----------------------
27    
28    If you install PCRE in the normal way, you will end up with an installed set of
29    man pages whose names all start with "pcre". The one that is called "pcre"
30    lists all the others. In addition to these man pages, the PCRE documentation is
31    supplied in two other forms; however, as there is no standard place to install
32    them, they are left in the doc directory of the unpacked source distribution.
33    These forms are:
34    
35      1. Files called doc/pcre.txt, doc/pcregrep.txt, and doc/pcretest.txt. The
36         first of these is a concatenation of the text forms of all the section 3
37         man pages except those that summarize individual functions. The other two
38         are the text forms of the section 1 man pages for the pcregrep and
39         pcretest commands. Text forms are provided for ease of scanning with text
40         editors or similar tools.
41    
42      2. A subdirectory called doc/html contains all the documentation in HTML
43         form, hyperlinked in various ways, and rooted in a file called
44         doc/index.html.
45    
46    
47    Contributions by users of PCRE
48    ------------------------------
49    
50    You can find contributions from PCRE users in the directory
51    
52      ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/Contrib
53    
54    where there is also a README file giving brief descriptions of what they are.
55    Several of them provide support for compiling PCRE on various flavours of
56    Windows systems (I myself do not use Windows). Some are complete in themselves;
57    others are pointers to URLs containing relevant files.
58    
59    
60    Building PCRE on a Unix-like system
61    -----------------------------------
62    
63    To build PCRE on a Unix-like system, first run the "configure" command from the
64    PCRE distribution directory, with your current directory set to the directory
65    where you want the files to be created. This command is a standard GNU
66    "autoconf" configuration script, for which generic instructions are supplied in
67    INSTALL.
68    
69    Most commonly, people build PCRE within its own distribution directory, and in
70    this case, on many systems, just running "./configure" is sufficient, but the
71    usual methods of changing standard defaults are available. For example:
72    
73    CFLAGS='-O2 -Wall' ./configure --prefix=/opt/local
74    
75    specifies that the C compiler should be run with the flags '-O2 -Wall' instead
76    of the default, and that "make install" should install PCRE under /opt/local
77    instead of the default /usr/local.
78    
79    If you want to build in a different directory, just run "configure" with that
80    directory as current. For example, suppose you have unpacked the PCRE source
81    into /source/pcre/pcre-xxx, but you want to build it in /build/pcre/pcre-xxx:
82    
83    cd /build/pcre/pcre-xxx
84    /source/pcre/pcre-xxx/configure
85    
86    There are some optional features that can be included or omitted from the PCRE
87    library. You can read more about them in the pcrebuild man page.
88    
89    . If you want to make use of the support for UTF-8 character strings in PCRE,
90      you must add --enable-utf8 to the "configure" command. Without it, the code
91      for handling UTF-8 is not included in the library. (Even when included, it
92      still has to be enabled by an option at run time.)
93    
94    . If, in addition to support for UTF-8 character strings, you want to include
95      support for the \P, \p, and \X sequences that recognize Unicode character
96      properties, you must add --enable-unicode-properties to the "configure"
97      command. This adds about 90K to the size of the library (in the form of a
98      property table); only the basic two-letter properties such as Lu are
99      supported.
100    
101    . You can build PCRE to recognized CR or NL as the newline character, instead
102      of whatever your compiler uses for "\n", by adding --newline-is-cr or
103      --newline-is-nl to the "configure" command, respectively. Only do this if you
104      really understand what you are doing. On traditional Unix-like systems, the
105      newline character is NL.
106    
107    . When called via the POSIX interface, PCRE uses malloc() to get additional
108      storage for processing capturing parentheses if there are more than 10 of
109      them. You can increase this threshold by setting, for example,
110    
111      --with-posix-malloc-threshold=20
112    
113      on the "configure" command.
114    
115    . PCRE has a counter which can be set to limit the amount of resources it uses.
116      If the limit is exceeded during a match, the match fails. The default is ten
117      million. You can change the default by setting, for example,
118    
119      --with-match-limit=500000
120    
121      on the "configure" command. This is just the default; individual calls to
122      pcre_exec() can supply their own value. There is discussion on the pcreapi
123      man page.
124    
125    . The default maximum compiled pattern size is around 64K. You can increase
126      this by adding --with-link-size=3 to the "configure" command. You can
127      increase it even more by setting --with-link-size=4, but this is unlikely
128      ever to be necessary. If you build PCRE with an increased link size, test 2
129      (and 5 if you are using UTF-8) will fail. Part of the output of these tests
130      is a representation of the compiled pattern, and this changes with the link
131      size.
132    
133    . You can build PCRE so that its match() function does not call itself
134      recursively. Instead, it uses blocks of data from the heap via special
135      functions pcre_stack_malloc() and pcre_stack_free() to save data that would
136      otherwise be saved on the stack. To build PCRE like this, use
137    
138      --disable-stack-for-recursion
139    
140      on the "configure" command. PCRE runs more slowly in this mode, but it may be
141      necessary in environments with limited stack sizes.
142    
143    The "configure" script builds seven files:
144    
145    . pcre.h is build by copying pcre.in and making substitutions
146    . Makefile is built by copying Makefile.in and making substitutions.
147    . config.h is built by copying config.in and making substitutions.
148    . pcre-config is built by copying pcre-config.in and making substitutions.
149    . libpcre.pc is data for the pkg-config command, built from libpcre.pc.in
150    . libtool is a script that builds shared and/or static libraries
151    . RunTest is a script for running tests
152    
153    Once "configure" has run, you can run "make". It builds two libraries called
154    libpcre and libpcreposix, a test program called pcretest, and the pcregrep
155    command. You can use "make install" to copy these, the public header files
156    pcre.h and pcreposix.h, and the man pages to appropriate live directories on
157    your system, in the normal way.
158    
159    
160    Retrieving configuration information on Unix-like systems
161    ---------------------------------------------------------
162    
163    Running "make install" also installs the command pcre-config, which can be used
164    to recall information about the PCRE configuration and installation. For
165    example:
166    
167      pcre-config --version
168    
169    prints the version number, and
170    
171      pcre-config --libs
172    
173    outputs information about where the library is installed. This command can be
174    included in makefiles for programs that use PCRE, saving the programmer from
175    having to remember too many details.
176    
177    The pkg-config command is another system for saving and retrieving information
178    about installed libraries. Instead of separate commands for each library, a
179    single command is used. For example:
180    
181      pkg-config --cflags pcre
182    
183    The data is held in *.pc files that are installed in a directory called
184    pkgconfig.
185    
186    
187    Shared libraries on Unix-like systems
188    -------------------------------------
189    
190    The default distribution builds PCRE as two shared libraries and two static
191    libraries, as long as the operating system supports shared libraries. Shared
192    library support relies on the "libtool" script which is built as part of the
193    "configure" process.
194    
195    The libtool script is used to compile and link both shared and static
196    libraries. They are placed in a subdirectory called .libs when they are newly
197    built. The programs pcretest and pcregrep are built to use these uninstalled
198    libraries (by means of wrapper scripts in the case of shared libraries). When
199    you use "make install" to install shared libraries, pcregrep and pcretest are
200    automatically re-built to use the newly installed shared libraries before being
201    installed themselves. However, the versions left in the source directory still
202    use the uninstalled libraries.
203    
204    To build PCRE using static libraries only you must use --disable-shared when
205    configuring it. For example:
206    
207    ./configure --prefix=/usr/gnu --disable-shared
208    
209    Then run "make" in the usual way. Similarly, you can use --disable-static to
210    build only shared libraries.
211    
212    
213    Cross-compiling on a Unix-like system
214    -------------------------------------
215    
216    You can specify CC and CFLAGS in the normal way to the "configure" command, in
217    order to cross-compile PCRE for some other host. However, during the building
218    process, the dftables.c source file is compiled *and run* on the local host, in
219    order to generate the default character tables (the chartables.c file). It
220    therefore needs to be compiled with the local compiler, not the cross compiler.
221    You can do this by specifying CC_FOR_BUILD (and if necessary CFLAGS_FOR_BUILD)
222    when calling the "configure" command. If they are not specified, they default
223    to the values of CC and CFLAGS.
224    
225    
226    Building on non-Unix systems
227    ----------------------------
228    
229    For a non-Unix system, read the comments in the file NON-UNIX-USE, though if
230    the system supports the use of "configure" and "make" you may be able to build
231    PCRE in the same way as for Unix systems.
232    
233    PCRE has been compiled on Windows systems and on Macintoshes, but I don't know
234    the details because I don't use those systems. It should be straightforward to
235    build PCRE on any system that has a Standard C compiler, because it uses only
236    Standard C functions.
237    
238    
239    Testing PCRE
240    ------------
241    
242    To test PCRE on a Unix system, run the RunTest script that is created by the
243    configuring process. (This can also be run by "make runtest", "make check", or
244    "make test".) For other systems, see the instructions in NON-UNIX-USE.
245    
246    The script runs the pcretest test program (which is documented in its own man
247    page) on each of the testinput files (in the testdata directory) in turn,
248    and compares the output with the contents of the corresponding testoutput file.
249    A file called testtry is used to hold the main output from pcretest
250    (testsavedregex is also used as a working file). To run pcretest on just one of
251    the test files, give its number as an argument to RunTest, for example:
252    
253      RunTest 2
254    
255    The first file can also be fed directly into the perltest script to check that
256    Perl gives the same results. The only difference you should see is in the first
257    few lines, where the Perl version is given instead of the PCRE version.
258    
259    The second set of tests check pcre_fullinfo(), pcre_info(), pcre_study(),
260    pcre_copy_substring(), pcre_get_substring(), pcre_get_substring_list(), error
261    detection, and run-time flags that are specific to PCRE, as well as the POSIX
262    wrapper API. It also uses the debugging flag to check some of the internals of
263    pcre_compile().
264    
265    If you build PCRE with a locale setting that is not the standard C locale, the
266    character tables may be different (see next paragraph). In some cases, this may
267    cause failures in the second set of tests. For example, in a locale where the
268    isprint() function yields TRUE for characters in the range 128-255, the use of
269    [:isascii:] inside a character class defines a different set of characters, and
270    this shows up in this test as a difference in the compiled code, which is being
271    listed for checking. Where the comparison test output contains [\x00-\x7f] the
272    test will contain [\x00-\xff], and similarly in some other cases. This is not a
273    bug in PCRE.
274    
275    The third set of tests checks pcre_maketables(), the facility for building a
276    set of character tables for a specific locale and using them instead of the
277    default tables. The tests make use of the "fr_FR" (French) locale. Before
278    running the test, the script checks for the presence of this locale by running
279    the "locale" command. If that command fails, or if it doesn't include "fr_FR"
280    in the list of available locales, the third test cannot be run, and a comment
281    is output to say why. If running this test produces instances of the error
282    
283      ** Failed to set locale "fr_FR"
284    
285    in the comparison output, it means that locale is not available on your system,
286    despite being listed by "locale". This does not mean that PCRE is broken.
287    
288    The fourth test checks the UTF-8 support. It is not run automatically unless
289    PCRE is built with UTF-8 support. To do this you must set --enable-utf8 when
290    running "configure". This file can be also fed directly to the perltest script,
291    provided you are running Perl 5.8 or higher. (For Perl 5.6, a small patch,
292    commented in the script, can be be used.)
293    
294    The fifth test checks error handling with UTF-8 encoding, and internal UTF-8
295    features of PCRE that are not relevant to Perl.
296    
297    The sixth and final test checks the support for Unicode character properties.
298    It it not run automatically unless PCRE is built with Unicode property support.
299    To to this you must set --enable-unicode-properties when running "configure".
300    
301    
302  Character tables  Character tables
303  ----------------  ----------------
304    
305  PCRE uses four tables for manipulating and identifying characters. The final  PCRE uses four tables for manipulating and identifying characters whose values
306  argument of the pcre_compile() function is a pointer to a block of memory  are less than 256. The final argument of the pcre_compile() function is a
307  containing the concatenated tables. A call to pcre_maketables() is used to  pointer to a block of memory containing the concatenated tables. A call to
308  generate a set of tables in the current locale. However, if the final argument  pcre_maketables() can be used to generate a set of tables in the current
309  is passed as NULL, a set of default tables that is built into the binary is  locale. If the final argument for pcre_compile() is passed as NULL, a set of
310  used.  default tables that is built into the binary is used.
311    
312  The source file called chartables.c contains the default set of tables. This is  The source file called chartables.c contains the default set of tables. This is
313  not supplied in the distribution, but is built by the program dftables  not supplied in the distribution, but is built by the program dftables
314  (compiled from dftables.c), which uses the ANSI C character handling functions  (compiled from dftables.c), which uses the ANSI C character handling functions
315  such as isalnum(), isalpha(), isupper(), islower(), etc. to build the table  such as isalnum(), isalpha(), isupper(), islower(), etc. to build the table
316  sources. This means that the default C locale set your system will control the  sources. This means that the default C locale which is set for your system will
317  contents of the tables. You can change the default tables by editing  control the contents of these default tables. You can change the default tables
318  chartables.c and then re-building PCRE. If you do this, you should probably  by editing chartables.c and then re-building PCRE. If you do this, you should
319  also edit Makefile to ensure that the file doesn't ever get re-generated.  probably also edit Makefile to ensure that the file doesn't ever get
320    re-generated.
321    
322  The first two 256-byte tables provide lower casing and case flipping functions,  The first two 256-byte tables provide lower casing and case flipping functions,
323  respectively. The next table consists of three 32-byte bit maps which identify  respectively. The next table consists of three 32-byte bit maps which identify
# Line 145  You should not alter the set of characte Line 338  You should not alter the set of characte
338  will cause PCRE to malfunction.  will cause PCRE to malfunction.
339    
340    
341  The pcretest program  Manifest
342  --------------------  --------
343    
344    The distribution should contain the following files:
345    
346    (A) The actual source files of the PCRE library functions and their
347        headers:
348    
349      dftables.c            auxiliary program for building chartables.c
350    
351      get.c                 )
352      maketables.c          )
353      study.c               ) source of the functions
354      pcre.c                )   in the library
355      pcreposix.c           )
356      printint.c            )
357    
358      ucp.c                 )
359      ucp.h                 ) source for the code that is used for
360      ucpinternal.h         )   Unicode property handling
361      ucptable.c            )
362      ucptypetable.c        )
363    
364      pcre.in               "source" for the header for the external API; pcre.h
365                              is built from this by "configure"
366      pcreposix.h           header for the external POSIX wrapper API
367      internal.h            header for internal use
368      config.in             template for config.h, which is built by configure
369    
370    (B) Auxiliary files:
371    
372      AUTHORS               information about the author of PCRE
373      ChangeLog             log of changes to the code
374      INSTALL               generic installation instructions
375      LICENCE               conditions for the use of PCRE
376      COPYING               the same, using GNU's standard name
377      Makefile.in           template for Unix Makefile, which is built by configure
378      NEWS                  important changes in this release
379      NON-UNIX-USE          notes on building PCRE on non-Unix systems
380      README                this file
381      RunTest.in            template for a Unix shell script for running tests
382      config.guess          ) files used by libtool,
383      config.sub            )   used only when building a shared library
384      configure             a configuring shell script (built by autoconf)
385      configure.in          the autoconf input used to build configure
386      doc/Tech.Notes        notes on the encoding
387      doc/*.3               man page sources for the PCRE functions
388      doc/*.1               man page sources for pcregrep and pcretest
389      doc/html/*            HTML documentation
390      doc/pcre.txt          plain text version of the man pages
391      doc/pcretest.txt      plain text documentation of test program
392      doc/perltest.txt      plain text documentation of Perl test program
393      install-sh            a shell script for installing files
394      libpcre.pc.in         "source" for libpcre.pc for pkg-config
395      ltmain.sh             file used to build a libtool script
396      mkinstalldirs         script for making install directories
397      pcretest.c            comprehensive test program
398      pcredemo.c            simple demonstration of coding calls to PCRE
399      perltest              Perl test program
400      pcregrep.c            source of a grep utility that uses PCRE
401      pcre-config.in        source of script which retains PCRE information
402      testdata/testinput1   test data, compatible with Perl
403      testdata/testinput2   test data for error messages and non-Perl things
404      testdata/testinput3   test data for locale-specific tests
405      testdata/testinput4   test data for UTF-8 tests compatible with Perl
406      testdata/testinput5   test data for other UTF-8 tests
407      testdata/testinput6   test data for Unicode property support tests
408      testdata/testoutput1  test results corresponding to testinput1
409      testdata/testoutput2  test results corresponding to testinput2
410      testdata/testoutput3  test results corresponding to testinput3
411      testdata/testoutput4  test results corresponding to testinput4
412      testdata/testoutput5  test results corresponding to testinput5
413      testdata/testoutput6  test results corresponding to testinput6
414    
415    (C) Auxiliary files for Win32 DLL
416    
417      dll.mk
418      libpcre.def
419      libpcreposix.def
420      pcre.def
421    
422  This program is intended for testing PCRE, but it can also be used for  (D) Auxiliary file for VPASCAL
 experimenting with regular expressions.  
423    
424  If it is given two filename arguments, it reads from the first and writes to    makevp.bat
 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/\  
   
 then a backslash is added to the end of the pattern. This provides a way of  
 testing the error condition that arises if a pattern finishes with a backslash,  
 because  
   
   /abc\/  
   
 is interpreted as the first line of a pattern that starts with "abc/", causing  
 pcretest to read the next line as a continuation of the regular expression.  
   
 The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,  
 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. These  
 options have the same effect as they do in Perl.  
   
 There are also some upper case options that do not match Perl options: /A, /E,  
 and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.  
   
 The /L option must be followed directly by the name of a locale, for example,  
   
   /pattern/Lfr  
   
 For this reason, it must be the last option 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 option, NULL is passed as the tables pointer; that  
 is, /L applies only to the expression on which it appears.  
   
 The /I option 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 option 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 option causes pcre_study() to be called after the expression has been  
 compiled, and the results used when the expression is matched.  
   
 The /M option causes information about the size of memory block used to hold  
 the compile pattern to be output.  
   
 Finally, the /P option causes pcretest to call PCRE via the POSIX wrapper API  
 rather than its native API. When this is done, all other options except /i and  
 /m 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  
   \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  
   Testing Perl-Compatible Regular Expressions  
   PCRE version 0.90 08-Sep-1997  
   
     re> /^abc(\d+)/  
   data> abc123  
     0: abc123  
     1: 123  
   data> xyz  
   No match  
   
 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 options. The contents  
 of testinput and testinput3 meet this condition.  
   
 The data lines are processed as Perl strings, so if they contain $ or @  
 characters, these have to be escaped. For this reason, all such characters in  
 the testinput file are escaped so that it can be used for perltest as well as  
 for pcretest, and the special upper case options such as /A that pcretest  
 recognizes are not used in this file. 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 options 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.  
425    
426  Philip Hazel <ph10@cam.ac.uk>  Philip Hazel <ph10@cam.ac.uk>
427  February 1999  September 2004

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