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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    
11    The PCRE APIs
12    -------------
13    
14    PCRE is written in C, and it has its own API. The distribution now includes a
15    set of C++ wrapper functions, courtesy of Google Inc. (see the pcrecpp man page
16    for details).
17    
18    Also included are a set of C wrapper functions that are based on the POSIX
19    API. These end up in the library called libpcreposix. Note that this just
20    provides a POSIX calling interface to PCRE: the regular expressions themselves
21    still follow Perl syntax and semantics. The header file for the POSIX-style
22    functions is called pcreposix.h. The official POSIX name is regex.h, but I
23    didn't want to risk possible problems with existing files of that name by
24    distributing it that way. To use it with an existing program that uses the
25    POSIX API, it will have to be renamed or pointed at by a link.
26    
27    If you are using the POSIX interface to PCRE and there is already a POSIX regex
28    library installed on your system, you must take care when linking programs to
29    ensure that they link with PCRE's libpcreposix library. Otherwise they may pick
30    up the "real" POSIX functions of the same name.
31    
32    
33    Documentation for PCRE
34    ----------------------
35    
36    If you install PCRE in the normal way, you will end up with an installed set of
37    man pages whose names all start with "pcre". The one that is just called "pcre"
38    lists all the others. In addition to these man pages, the PCRE documentation is
39    supplied in two other forms; however, as there is no standard place to install
40    them, they are left in the doc directory of the unpacked source distribution.
41    These forms are:
42    
43      1. Files called doc/pcre.txt, doc/pcregrep.txt, and doc/pcretest.txt. The
44         first of these is a concatenation of the text forms of all the section 3
45         man pages except those that summarize individual functions. The other two
46         are the text forms of the section 1 man pages for the pcregrep and
47         pcretest commands. Text forms are provided for ease of scanning with text
48         editors or similar tools.
49    
50      2. A subdirectory called doc/html contains all the documentation in HTML
51         form, hyperlinked in various ways, and rooted in a file called
52         doc/index.html.
53    
54    
55    Contributions by users of PCRE
56    ------------------------------
57    
58    You can find contributions from PCRE users in the directory
59    
60      ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/Contrib
61    
62    where there is also a README file giving brief descriptions of what they are.
63    Several of them provide support for compiling PCRE on various flavours of
64    Windows systems (I myself do not use Windows). Some are complete in themselves;
65    others are pointers to URLs containing relevant files.
66    
67    
68    Building on non-Unix systems
69    ----------------------------
70    
71    For a non-Unix system, read the comments in the file NON-UNIX-USE, though if
72    the system supports the use of "configure" and "make" you may be able to build
73    PCRE in the same way as for Unix systems.
74    
75    PCRE has been compiled on Windows systems and on Macintoshes, but I don't know
76    the details because I don't use those systems. It should be straightforward to
77    build PCRE on any system that has a Standard C compiler and library, because it
78    uses only Standard C functions.
79    
80    
81    Building PCRE on a Unix-like system
82    -----------------------------------
83    
84    If you are using HP's ANSI C++ compiler (aCC), please see the special note
85    in the section entitled "Using HP's ANSI C++ compiler (aCC)" below.
86    
87    To build PCRE on a Unix-like system, first run the "configure" command from the
88    PCRE distribution directory, with your current directory set to the directory
89    where you want the files to be created. This command is a standard GNU
90    "autoconf" configuration script, for which generic instructions are supplied in
91    INSTALL.
92    
93    Most commonly, people build PCRE within its own distribution directory, and in
94    this case, on many systems, just running "./configure" is sufficient, but the
95    usual methods of changing standard defaults are available. For example:
96    
97    CFLAGS='-O2 -Wall' ./configure --prefix=/opt/local
98    
99    specifies that the C compiler should be run with the flags '-O2 -Wall' instead
100    of the default, and that "make install" should install PCRE under /opt/local
101    instead of the default /usr/local.
102    
103    If you want to build in a different directory, just run "configure" with that
104    directory as current. For example, suppose you have unpacked the PCRE source
105    into /source/pcre/pcre-xxx, but you want to build it in /build/pcre/pcre-xxx:
106    
107    cd /build/pcre/pcre-xxx
108    /source/pcre/pcre-xxx/configure
109    
110    PCRE is written in C and is normally compiled as a C library. However, it is
111    possible to build it as a C++ library, though the provided building apparatus
112    does not have any features to support this.
113    
114    There are some optional features that can be included or omitted from the PCRE
115    library. You can read more about them in the pcrebuild man page.
116    
117    . If you want to suppress the building of the C++ wrapper library, you can add
118      --disable-cpp to the "configure" command. Otherwise, when "configure" is run,
119      will try to find a C++ compiler and C++ header files, and if it succeeds, it
120      will try to build the C++ wrapper.
121    
122    . If you want to make use of the support for UTF-8 character strings in PCRE,
123      you must add --enable-utf8 to the "configure" command. Without it, the code
124      for handling UTF-8 is not included in the library. (Even when included, it
125      still has to be enabled by an option at run time.)
126    
127    . If, in addition to support for UTF-8 character strings, you want to include
128      support for the \P, \p, and \X sequences that recognize Unicode character
129      properties, you must add --enable-unicode-properties to the "configure"
130      command. This adds about 30K to the size of the library (in the form of a
131      property table); only the basic two-letter properties such as Lu are
132      supported.
133    
134    . You can build PCRE to recognize either CR or LF or the sequence CRLF or any
135      of the Unicode newline sequences as indicating the end of a line. Whatever
136      you specify at build time is the default; the caller of PCRE can change the
137      selection at run time. The default newline indicator is a single LF character
138      (the Unix standard). You can specify the default newline indicator by adding
139      --newline-is-cr or --newline-is-lf or --newline-is-crlf or --newline-is-any
140      to the "configure" command, respectively.
141    
142      If you specify --newline-is-cr or --newline-is-crlf, some of the standard
143      tests will fail, because the lines in the test files end with LF. Even if
144      the files are edited to change the line endings, there are likely to be some
145      failures. With --newline-is-any, many tests should succeed, but there may be
146      some failures.
147    
148    . When called via the POSIX interface, PCRE uses malloc() to get additional
149      storage for processing capturing parentheses if there are more than 10 of
150      them. You can increase this threshold by setting, for example,
151    
152      --with-posix-malloc-threshold=20
153    
154      on the "configure" command.
155    
156    . PCRE has a counter that can be set to limit the amount of resources it uses.
157      If the limit is exceeded during a match, the match fails. The default is ten
158      million. You can change the default by setting, for example,
159    
160      --with-match-limit=500000
161    
162      on the "configure" command. This is just the default; individual calls to
163      pcre_exec() can supply their own value. There is discussion on the pcreapi
164      man page.
165    
166    . There is a separate counter that limits the depth of recursive function calls
167      during a matching process. This also has a default of ten million, which is
168      essentially "unlimited". You can change the default by setting, for example,
169    
170      --with-match-limit-recursion=500000
171    
172      Recursive function calls use up the runtime stack; running out of stack can
173      cause programs to crash in strange ways. There is a discussion about stack
174      sizes in the pcrestack man page.
175    
176    . The default maximum compiled pattern size is around 64K. You can increase
177      this by adding --with-link-size=3 to the "configure" command. You can
178      increase it even more by setting --with-link-size=4, but this is unlikely
179      ever to be necessary. If you build PCRE with an increased link size, test 2
180      (and 5 if you are using UTF-8) will fail. Part of the output of these tests
181      is a representation of the compiled pattern, and this changes with the link
182      size.
183    
184    . You can build PCRE so that its internal match() function that is called from
185      pcre_exec() does not call itself recursively. Instead, it uses blocks of data
186      from the heap via special functions pcre_stack_malloc() and pcre_stack_free()
187      to save data that would otherwise be saved on the stack. To build PCRE like
188      this, use
189    
190      --disable-stack-for-recursion
191    
192      on the "configure" command. PCRE runs more slowly in this mode, but it may be
193      necessary in environments with limited stack sizes. This applies only to the
194      pcre_exec() function; it does not apply to pcre_dfa_exec(), which does not
195      use deeply nested recursion.
196    
197    The "configure" script builds eight files for the basic C library:
198    
199    . Makefile is the makefile that builds the library
200    . config.h contains build-time configuration options for the library
201    . pcre-config is a script that shows the settings of "configure" options
202    . libpcre.pc is data for the pkg-config command
203    . libtool is a script that builds shared and/or static libraries
204    . RunTest is a script for running tests on the library
205    . RunGrepTest is a script for running tests on the pcregrep command
206    
207    In addition, if a C++ compiler is found, the following are also built:
208    
209    . pcrecpp.h is the header file for programs that call PCRE via the C++ wrapper
210    . pcre_stringpiece.h is the header for the C++ "stringpiece" functions
211    
212    ChangeLog         log of changes to the code  The "configure" script also creates config.status, which is an executable
213    LICENCE           conditions for the use of PCRE  script that can be run to recreate the configuration, and config.log, which
214    Makefile          for building PCRE  contains compiler output from tests that "configure" runs.
   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  
   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  
   
 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.  
215    
216  The fourth set of tests checks pcre_maketables(), the facility for building a  Once "configure" has run, you can run "make". It builds two libraries, called
217    libpcre and libpcreposix, a test program called pcretest, and the pcregrep
218    command. If a C++ compiler was found on your system, it also builds the C++
219    wrapper library, which is called libpcrecpp, and some test programs called
220    pcrecpp_unittest, pcre_scanner_unittest, and pcre_stringpiece_unittest.
221    
222    The command "make test" runs all the appropriate tests. Details of the PCRE
223    tests are given in a separate section of this document, below.
224    
225    You can use "make install" to copy the libraries, the public header files
226    pcre.h, pcreposix.h, pcrecpp.h, and pcre_stringpiece.h (the last two only if
227    the C++ wrapper was built), and the man pages to appropriate live directories
228    on your system, in the normal way.
229    
230    If you want to remove PCRE from your system, you can run "make uninstall".
231    This removes all the files that "make install" installed. However, it does not
232    remove any directories, because these are often shared with other programs.
233    
234    
235    Retrieving configuration information on Unix-like systems
236    ---------------------------------------------------------
237    
238    Running "make install" also installs the command pcre-config, which can be used
239    to recall information about the PCRE configuration and installation. For
240    example:
241    
242      pcre-config --version
243    
244    prints the version number, and
245    
246      pcre-config --libs
247    
248    outputs information about where the library is installed. This command can be
249    included in makefiles for programs that use PCRE, saving the programmer from
250    having to remember too many details.
251    
252    The pkg-config command is another system for saving and retrieving information
253    about installed libraries. Instead of separate commands for each library, a
254    single command is used. For example:
255    
256      pkg-config --cflags pcre
257    
258    The data is held in *.pc files that are installed in a directory called
259    pkgconfig.
260    
261    
262    Shared libraries on Unix-like systems
263    -------------------------------------
264    
265    The default distribution builds PCRE as shared libraries and static libraries,
266    as long as the operating system supports shared libraries. Shared library
267    support relies on the "libtool" script which is built as part of the
268    "configure" process.
269    
270    The libtool script is used to compile and link both shared and static
271    libraries. They are placed in a subdirectory called .libs when they are newly
272    built. The programs pcretest and pcregrep are built to use these uninstalled
273    libraries (by means of wrapper scripts in the case of shared libraries). When
274    you use "make install" to install shared libraries, pcregrep and pcretest are
275    automatically re-built to use the newly installed shared libraries before being
276    installed themselves. However, the versions left in the source directory still
277    use the uninstalled libraries.
278    
279    To build PCRE using static libraries only you must use --disable-shared when
280    configuring it. For example:
281    
282    ./configure --prefix=/usr/gnu --disable-shared
283    
284    Then run "make" in the usual way. Similarly, you can use --disable-static to
285    build only shared libraries.
286    
287    
288    Cross-compiling on a Unix-like system
289    -------------------------------------
290    
291    You can specify CC and CFLAGS in the normal way to the "configure" command, in
292    order to cross-compile PCRE for some other host. However, during the building
293    process, the dftables.c source file is compiled *and run* on the local host, in
294    order to generate the default character tables (the chartables.c file). It
295    therefore needs to be compiled with the local compiler, not the cross compiler.
296    You can do this by specifying CC_FOR_BUILD (and if necessary CFLAGS_FOR_BUILD;
297    there are also CXX_FOR_BUILD and CXXFLAGS_FOR_BUILD for the C++ wrapper)
298    when calling the "configure" command. If they are not specified, they default
299    to the values of CC and CFLAGS.
300    
301    
302    Using HP's ANSI C++ compiler (aCC)
303    ----------------------------------
304    
305    Unless C++ support is disabled by specifying the "--disable-cpp" option of the
306    "configure" script, you *must* include the "-AA" option in the CXXFLAGS
307    environment variable in order for the C++ components to compile correctly.
308    
309    Also, note that the aCC compiler on PA-RISC platforms may have a defect whereby
310    needed libraries fail to get included when specifying the "-AA" compiler
311    option. If you experience unresolved symbols when linking the C++ programs,
312    use the workaround of specifying the following environment variable prior to
313    running the "configure" script:
314    
315      CXXLDFLAGS="-lstd_v2 -lCsup_v2"
316    
317    
318    Testing PCRE
319    ------------
320    
321    To test PCRE on a Unix system, run the RunTest script that is created by the
322    configuring process. There is also a script called RunGrepTest that tests the
323    options of the pcregrep command. If the C++ wrapper library is build, three
324    test programs called pcrecpp_unittest, pcre_scanner_unittest, and
325    pcre_stringpiece_unittest are provided.
326    
327    Both the scripts and all the program tests are run if you obey "make runtest",
328    "make check", or "make test". For other systems, see the instructions in
329    NON-UNIX-USE.
330    
331    The RunTest script runs the pcretest test program (which is documented in its
332    own man page) on each of the testinput files (in the testdata directory) in
333    turn, and compares the output with the contents of the corresponding testoutput
334    files. A file called testtry is used to hold the main output from pcretest
335    (testsavedregex is also used as a working file). To run pcretest on just one of
336    the test files, give its number as an argument to RunTest, for example:
337    
338      RunTest 2
339    
340    The first test file can also be fed directly into the perltest script to check
341    that Perl gives the same results. The only difference you should see is in the
342    first few lines, where the Perl version is given instead of the PCRE version.
343    
344    The second set of tests check pcre_fullinfo(), pcre_info(), pcre_study(),
345    pcre_copy_substring(), pcre_get_substring(), pcre_get_substring_list(), error
346    detection, and run-time flags that are specific to PCRE, as well as the POSIX
347    wrapper API. It also uses the debugging flag to check some of the internals of
348    pcre_compile().
349    
350    If you build PCRE with a locale setting that is not the standard C locale, the
351    character tables may be different (see next paragraph). In some cases, this may
352    cause failures in the second set of tests. For example, in a locale where the
353    isprint() function yields TRUE for characters in the range 128-255, the use of
354    [:isascii:] inside a character class defines a different set of characters, and
355    this shows up in this test as a difference in the compiled code, which is being
356    listed for checking. Where the comparison test output contains [\x00-\x7f] the
357    test will contain [\x00-\xff], and similarly in some other cases. This is not a
358    bug in PCRE.
359    
360    The third set of tests checks pcre_maketables(), the facility for building a
361  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
362  default tables. The tests make use of the "fr" (French) locale. Before running  default tables. The tests make use of the "fr_FR" (French) locale. Before
363  the test, the script checks for the presence of this locale by running the  running the test, the script checks for the presence of this locale by running
364  "locale" command. If that command fails, or if it doesn't include "fr" in the  the "locale" command. If that command fails, or if it doesn't include "fr_FR"
365  list of available locales, the fourth test cannot be run, and a comment is  in the list of available locales, the third test cannot be run, and a comment
366  output to say why. If running this test produces instances of the error  is output to say why. If running this test produces instances of the error
367    
368    ** Failed to set locale "fr"    ** Failed to set locale "fr_FR"
369    
370  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,
371  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.
372    
373  To install PCRE, copy libpcre.a to any suitable library directory (e.g.  The fourth test checks the UTF-8 support. It is not run automatically unless
374  /usr/local/lib), pcre.h to any suitable include directory (e.g.  PCRE is built with UTF-8 support. To do this you must set --enable-utf8 when
375  /usr/local/include), and pcre.3 to any suitable man directory (e.g.  running "configure". This file can be also fed directly to the perltest script,
376  /usr/local/man/man3).  provided you are running Perl 5.8 or higher. (For Perl 5.6, a small patch,
377    commented in the script, can be be used.)
378  To install the pgrep command, copy it to any suitable binary directory, (e.g.  
379  /usr/local/bin) and pgrep.1 to any suitable man directory (e.g.  The fifth test checks error handling with UTF-8 encoding, and internal UTF-8
380  /usr/local/man/man1).  features of PCRE that are not relevant to Perl.
381    
382  PCRE has its own native API, but a set of "wrapper" functions that are based on  The sixth and test checks the support for Unicode character properties. It it
383  the POSIX API are also supplied in the library libpcreposix.a. Note that this  not run automatically unless PCRE is built with Unicode property support. To to
384  just provides a POSIX calling interface to PCRE: the regular expressions  this you must set --enable-unicode-properties when running "configure".
385  themselves still follow Perl syntax and semantics. The header file  
386  for the POSIX-style functions is called pcreposix.h. The official POSIX name is  The seventh, eighth, and ninth tests check the pcre_dfa_exec() alternative
387  regex.h, but I didn't want to risk possible problems with existing files of  matching function, in non-UTF-8 mode, UTF-8 mode, and UTF-8 mode with Unicode
388  that name by distributing it that way. To use it with an existing program that  property support, respectively. The eighth and ninth tests are not run
389  uses the POSIX API, it will have to be renamed or pointed at by a link.  automatically unless PCRE is build with the relevant support.
390    
391    
392  Character tables  Character tables
393  ----------------  ----------------
394    
395  PCRE uses four tables for manipulating and identifying characters. The final  PCRE uses four tables for manipulating and identifying characters whose values
396  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
397  containing the concatenated tables. A call to pcre_maketables() can be used to  pointer to a block of memory containing the concatenated tables. A call to
398  generate a set of tables in the current locale. If the final argument for  pcre_maketables() can be used to generate a set of tables in the current
399  pcre_compile() is passed as NULL, a set of default tables that is built into  locale. If the final argument for pcre_compile() is passed as NULL, a set of
400  the binary is used.  default tables that is built into the binary is used.
401    
402  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
403  not supplied in the distribution, but is built by the program dftables  not supplied in the distribution, but is built by the program dftables
# Line 161  You should not alter the set of characte Line 428  You should not alter the set of characte
428  will cause PCRE to malfunction.  will cause PCRE to malfunction.
429    
430    
431  The pcretest program  Manifest
432  --------------------  --------
433    
434  This program is intended for testing PCRE, but it can also be used for  The distribution should contain the following files:
 experimenting with regular expressions.  
   
 If it is given two filename arguments, it reads from the first and writes to  
 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 is done to provide a  
 way of testing the error condition that arises if a pattern finishes with a  
 backslash, because  
   
   /abc\/  
   
 is interpreted as the first line of a pattern that starts with "abc/", causing  
 pcretest to read the next line as a continuation of the regular expression.  
   
 The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,  
 PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For  
 example:  
435    
436    /caseless/i  (A) The actual source files of the PCRE library functions and their
437        headers:
438    
439  These modifier letters have the same effect as they do in Perl. There are    dftables.c            auxiliary program for building chartables.c
 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. The /g modifier behaves similarly to the way it does  
 in Perl. 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 start_offset argument to pcre_exec() to start searching at a new point  
 within the entire string, 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).  
   
 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 information about the size of memory block used to hold  
 the compile 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  
   \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 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.  
440    
441  Philip Hazel <ph10@cam.ac.uk>    pcreposix.c           )
442  June 1999    pcre_compile.c        )
443      pcre_config.c         )
444      pcre_dfa_exec.c       )
445      pcre_exec.c           )
446      pcre_fullinfo.c       )
447      pcre_get.c            ) sources for the functions in the library,
448      pcre_globals.c        )   and some internal functions that they use
449      pcre_info.c           )
450      pcre_maketables.c     )
451      pcre_newline.c        )
452      pcre_ord2utf8.c       )
453      pcre_refcount.c       )
454      pcre_study.c          )
455      pcre_tables.c         )
456      pcre_try_flipped.c    )
457      pcre_ucp_searchfuncs.c)
458      pcre_valid_utf8.c     )
459      pcre_version.c        )
460      pcre_xclass.c         )
461    
462      pcre_printint.src     ) debugging function that is #included in pcretest, and
463                            )   can also be #included in pcre_compile()
464    
465      pcre.h                the public PCRE header file
466      pcreposix.h           header for the external POSIX wrapper API
467      pcre_internal.h       header for internal use
468      ucp.h                 ) headers concerned with
469      ucpinternal.h         )   Unicode property handling
470      ucptable.h            ) (this one is the data table)
471      config.in             template for config.h, which is built by configure
472    
473      pcrecpp.h             the header file for the C++ wrapper
474      pcrecpparg.h.in       "source" for another C++ header file
475      pcrecpp.cc            )
476      pcre_scanner.cc       ) source for the C++ wrapper library
477    
478      pcre_stringpiece.h.in "source" for pcre_stringpiece.h, the header for the
479                              C++ stringpiece functions
480      pcre_stringpiece.cc   source for the C++ stringpiece functions
481    
482    (B) Auxiliary files:
483    
484      AUTHORS               information about the author of PCRE
485      ChangeLog             log of changes to the code
486      INSTALL               generic installation instructions
487      LICENCE               conditions for the use of PCRE
488      COPYING               the same, using GNU's standard name
489      Makefile.in           template for Unix Makefile, which is built by configure
490      NEWS                  important changes in this release
491      NON-UNIX-USE          notes on building PCRE on non-Unix systems
492      README                this file
493      RunTest.in            template for a Unix shell script for running tests
494      RunGrepTest.in        template for a Unix shell script for pcregrep tests
495      config.guess          ) files used by libtool,
496      config.sub            )   used only when building a shared library
497      config.h.in           "source" for the config.h header file
498      configure             a configuring shell script (built by autoconf)
499      configure.ac          the autoconf input used to build configure
500      doc/Tech.Notes        notes on the encoding
501      doc/*.3               man page sources for the PCRE functions
502      doc/*.1               man page sources for pcregrep and pcretest
503      doc/html/*            HTML documentation
504      doc/pcre.txt          plain text version of the man pages
505      doc/pcretest.txt      plain text documentation of test program
506      doc/perltest.txt      plain text documentation of Perl test program
507      install-sh            a shell script for installing files
508      libpcre.pc.in         "source" for libpcre.pc for pkg-config
509      ltmain.sh             file used to build a libtool script
510      mkinstalldirs         script for making install directories
511      pcretest.c            comprehensive test program
512      pcredemo.c            simple demonstration of coding calls to PCRE
513      perltest.pl           Perl test program
514      pcregrep.c            source of a grep utility that uses PCRE
515      pcre-config.in        source of script which retains PCRE information
516      pcrecpp_unittest.c           )
517      pcre_scanner_unittest.c      ) test programs for the C++ wrapper
518      pcre_stringpiece_unittest.c  )
519      testdata/testinput*   test data for main library tests
520      testdata/testoutput*  expected test results
521      testdata/grep*        input and output for pcregrep tests
522    
523    (C) Auxiliary files for Win32 DLL
524    
525      libpcre.def
526      libpcreposix.def
527    
528    (D) Auxiliary file for VPASCAL
529    
530      makevp.bat
531    
532    Philip Hazel
533    Email local part: ph10
534    Email domain: cam.ac.uk
535    March 2007

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