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1 nigel 41 README file for PCRE (Perl-compatible regular expression library)
2     -----------------------------------------------------------------
3 nigel 3
4 nigel 43 The latest release of PCRE is always available from
5    
6     ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.tar.gz
7    
8 nigel 41 Please read the NEWS file if you are upgrading from a previous release.
9 nigel 23
10 nigel 35
11 nigel 77 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 nigel 73 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 nigel 49
32 nigel 73
33 nigel 75 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 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 nigel 53 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 nigel 63 Building PCRE on a Unix-like system
69     -----------------------------------
70 nigel 3
71 nigel 63 To build PCRE on a Unix-like system, first run the "configure" command from the
72     PCRE distribution directory, with your current directory set to the directory
73     where you want the files to be created. This command is a standard GNU
74     "autoconf" configuration script, for which generic instructions are supplied in
75     INSTALL.
76 nigel 3
77 nigel 53 Most commonly, people build PCRE within its own distribution directory, and in
78     this case, on many systems, just running "./configure" is sufficient, but the
79 nigel 75 usual methods of changing standard defaults are available. For example:
80 nigel 53
81 nigel 41 CFLAGS='-O2 -Wall' ./configure --prefix=/opt/local
82    
83     specifies that the C compiler should be run with the flags '-O2 -Wall' instead
84     of the default, and that "make install" should install PCRE under /opt/local
85 nigel 49 instead of the default /usr/local.
86 nigel 41
87 nigel 53 If you want to build in a different directory, just run "configure" with that
88     directory as current. For example, suppose you have unpacked the PCRE source
89     into /source/pcre/pcre-xxx, but you want to build it in /build/pcre/pcre-xxx:
90    
91     cd /build/pcre/pcre-xxx
92     /source/pcre/pcre-xxx/configure
93    
94 nigel 63 There are some optional features that can be included or omitted from the PCRE
95     library. You can read more about them in the pcrebuild man page.
96 nigel 49
97 nigel 83 . If you want to suppress the building of the C++ wrapper library, you can add
98     --disable-cpp to the "configure" command. Otherwise, when "configure" is run,
99     will try to find a C++ compiler and C++ header files, and if it succeeds, it
100     will try to build the C++ wrapper.
101    
102 nigel 63 . If you want to make use of the support for UTF-8 character strings in PCRE,
103     you must add --enable-utf8 to the "configure" command. Without it, the code
104     for handling UTF-8 is not included in the library. (Even when included, it
105     still has to be enabled by an option at run time.)
106    
107 nigel 75 . If, in addition to support for UTF-8 character strings, you want to include
108     support for the \P, \p, and \X sequences that recognize Unicode character
109     properties, you must add --enable-unicode-properties to the "configure"
110     command. This adds about 90K to the size of the library (in the form of a
111     property table); only the basic two-letter properties such as Lu are
112     supported.
113    
114 nigel 63 . You can build PCRE to recognized CR or NL as the newline character, instead
115     of whatever your compiler uses for "\n", by adding --newline-is-cr or
116     --newline-is-nl to the "configure" command, respectively. Only do this if you
117     really understand what you are doing. On traditional Unix-like systems, the
118     newline character is NL.
119    
120     . When called via the POSIX interface, PCRE uses malloc() to get additional
121     storage for processing capturing parentheses if there are more than 10 of
122     them. You can increase this threshold by setting, for example,
123    
124     --with-posix-malloc-threshold=20
125    
126     on the "configure" command.
127    
128 nigel 77 . PCRE has a counter that can be set to limit the amount of resources it uses.
129 nigel 63 If the limit is exceeded during a match, the match fails. The default is ten
130     million. You can change the default by setting, for example,
131    
132     --with-match-limit=500000
133    
134     on the "configure" command. This is just the default; individual calls to
135     pcre_exec() can supply their own value. There is discussion on the pcreapi
136     man page.
137    
138     . The default maximum compiled pattern size is around 64K. You can increase
139     this by adding --with-link-size=3 to the "configure" command. You can
140     increase it even more by setting --with-link-size=4, but this is unlikely
141     ever to be necessary. If you build PCRE with an increased link size, test 2
142     (and 5 if you are using UTF-8) will fail. Part of the output of these tests
143     is a representation of the compiled pattern, and this changes with the link
144     size.
145    
146 nigel 77 . You can build PCRE so that its internal match() function that is called from
147     pcre_exec() does not call itself recursively. Instead, it uses blocks of data
148     from the heap via special functions pcre_stack_malloc() and pcre_stack_free()
149     to save data that would otherwise be saved on the stack. To build PCRE like
150     this, use
151 nigel 73
152     --disable-stack-for-recursion
153    
154     on the "configure" command. PCRE runs more slowly in this mode, but it may be
155 nigel 77 necessary in environments with limited stack sizes. This applies only to the
156     pcre_exec() function; it does not apply to pcre_dfa_exec(), which does not
157     use deeply nested recursion.
158 nigel 73
159 nigel 77 The "configure" script builds eight files for the basic C library:
160 nigel 49
161 nigel 77 . pcre.h is the header file for C programs that call PCRE
162     . Makefile is the makefile that builds the library
163     . config.h contains build-time configuration options for the library
164     . pcre-config is a script that shows the settings of "configure" options
165     . libpcre.pc is data for the pkg-config command
166 nigel 75 . libtool is a script that builds shared and/or static libraries
167 nigel 77 . RunTest is a script for running tests on the library
168     . RunGrepTest is a script for running tests on the pcregrep command
169 nigel 41
170 nigel 77 In addition, if a C++ compiler is found, the following are also built:
171    
172     . pcrecpp.h is the header file for programs that call PCRE via the C++ wrapper
173     . pcre_stringpiece.h is the header for the C++ "stringpiece" functions
174    
175     The "configure" script also creates config.status, which is an executable
176     script that can be run to recreate the configuration, and config.log, which
177     contains compiler output from tests that "configure" runs.
178    
179     Once "configure" has run, you can run "make". It builds two libraries, called
180 nigel 49 libpcre and libpcreposix, a test program called pcretest, and the pcregrep
181 nigel 77 command. If a C++ compiler was found on your system, it also builds the C++
182     wrapper library, which is called libpcrecpp, and some test programs called
183     pcrecpp_unittest, pcre_scanner_unittest, and pcre_stringpiece_unittest.
184 nigel 3
185 nigel 77 The command "make test" runs all the appropriate tests. Details of the PCRE
186     tests are given in a separate section of this document, below.
187 nigel 75
188 nigel 77 You can use "make install" to copy the libraries, the public header files
189     pcre.h, pcreposix.h, pcrecpp.h, and pcre_stringpiece.h (the last two only if
190     the C++ wrapper was built), and the man pages to appropriate live directories
191     on your system, in the normal way.
192    
193     If you want to remove PCRE from your system, you can run "make uninstall".
194     This removes all the files that "make install" installed. However, it does not
195     remove any directories, because these are often shared with other programs.
196    
197    
198 nigel 75 Retrieving configuration information on Unix-like systems
199     ---------------------------------------------------------
200    
201 nigel 43 Running "make install" also installs the command pcre-config, which can be used
202     to recall information about the PCRE configuration and installation. For
203 nigel 75 example:
204 nigel 37
205 nigel 43 pcre-config --version
206    
207     prints the version number, and
208    
209 nigel 75 pcre-config --libs
210 nigel 43
211     outputs information about where the library is installed. This command can be
212     included in makefiles for programs that use PCRE, saving the programmer from
213     having to remember too many details.
214    
215 nigel 75 The pkg-config command is another system for saving and retrieving information
216     about installed libraries. Instead of separate commands for each library, a
217     single command is used. For example:
218 nigel 43
219 nigel 75 pkg-config --cflags pcre
220    
221     The data is held in *.pc files that are installed in a directory called
222     pkgconfig.
223    
224    
225 nigel 63 Shared libraries on Unix-like systems
226     -------------------------------------
227 nigel 53
228 nigel 77 The default distribution builds PCRE as shared libraries and static libraries,
229     as long as the operating system supports shared libraries. Shared library
230     support relies on the "libtool" script which is built as part of the
231 nigel 53 "configure" process.
232 nigel 39
233 nigel 53 The libtool script is used to compile and link both shared and static
234     libraries. They are placed in a subdirectory called .libs when they are newly
235     built. The programs pcretest and pcregrep are built to use these uninstalled
236     libraries (by means of wrapper scripts in the case of shared libraries). When
237     you use "make install" to install shared libraries, pcregrep and pcretest are
238     automatically re-built to use the newly installed shared libraries before being
239     installed themselves. However, the versions left in the source directory still
240     use the uninstalled libraries.
241    
242     To build PCRE using static libraries only you must use --disable-shared when
243 nigel 75 configuring it. For example:
244 nigel 3
245 nigel 43 ./configure --prefix=/usr/gnu --disable-shared
246 nigel 41
247 nigel 53 Then run "make" in the usual way. Similarly, you can use --disable-static to
248     build only shared libraries.
249 nigel 41
250 nigel 43
251 nigel 63 Cross-compiling on a Unix-like system
252     -------------------------------------
253    
254     You can specify CC and CFLAGS in the normal way to the "configure" command, in
255     order to cross-compile PCRE for some other host. However, during the building
256     process, the dftables.c source file is compiled *and run* on the local host, in
257     order to generate the default character tables (the chartables.c file). It
258     therefore needs to be compiled with the local compiler, not the cross compiler.
259 nigel 77 You can do this by specifying CC_FOR_BUILD (and if necessary CFLAGS_FOR_BUILD;
260     there are also CXX_FOR_BUILD and CXXFLAGS_FOR_BUILD for the C++ wrapper)
261 nigel 73 when calling the "configure" command. If they are not specified, they default
262     to the values of CC and CFLAGS.
263 nigel 63
264    
265 nigel 41 Building on non-Unix systems
266     ----------------------------
267    
268 nigel 73 For a non-Unix system, read the comments in the file NON-UNIX-USE, though if
269     the system supports the use of "configure" and "make" you may be able to build
270     PCRE in the same way as for Unix systems.
271    
272     PCRE has been compiled on Windows systems and on Macintoshes, but I don't know
273     the details because I don't use those systems. It should be straightforward to
274 nigel 41 build PCRE on any system that has a Standard C compiler, because it uses only
275     Standard C functions.
276    
277    
278     Testing PCRE
279     ------------
280    
281 nigel 53 To test PCRE on a Unix system, run the RunTest script that is created by the
282 nigel 77 configuring process. There is also a script called RunGrepTest that tests the
283     options of the pcregrep command. If the C++ wrapper library is build, three
284     test programs called pcrecpp_unittest, pcre_scanner_unittest, and
285     pcre_stringpiece_unittest are provided.
286 nigel 41
287 nigel 77 Both the scripts and all the program tests are run if you obey "make runtest",
288     "make check", or "make test". For other systems, see the instructions in
289     NON-UNIX-USE.
290    
291     The RunTest script runs the pcretest test program (which is documented in its
292     own man page) on each of the testinput files (in the testdata directory) in
293     turn, and compares the output with the contents of the corresponding testoutput
294     file. A file called testtry is used to hold the main output from pcretest
295 nigel 75 (testsavedregex is also used as a working file). To run pcretest on just one of
296     the test files, give its number as an argument to RunTest, for example:
297 nigel 41
298 nigel 63 RunTest 2
299 nigel 3
300 nigel 63 The first file can also be fed directly into the perltest script to check that
301     Perl gives the same results. The only difference you should see is in the first
302     few lines, where the Perl version is given instead of the PCRE version.
303 nigel 3
304 nigel 49 The second set of tests check pcre_fullinfo(), pcre_info(), pcre_study(),
305     pcre_copy_substring(), pcre_get_substring(), pcre_get_substring_list(), error
306     detection, and run-time flags that are specific to PCRE, as well as the POSIX
307     wrapper API. It also uses the debugging flag to check some of the internals of
308     pcre_compile().
309 nigel 7
310 nigel 49 If you build PCRE with a locale setting that is not the standard C locale, the
311     character tables may be different (see next paragraph). In some cases, this may
312     cause failures in the second set of tests. For example, in a locale where the
313     isprint() function yields TRUE for characters in the range 128-255, the use of
314     [:isascii:] inside a character class defines a different set of characters, and
315     this shows up in this test as a difference in the compiled code, which is being
316     listed for checking. Where the comparison test output contains [\x00-\x7f] the
317     test will contain [\x00-\xff], and similarly in some other cases. This is not a
318     bug in PCRE.
319    
320 nigel 63 The third set of tests checks pcre_maketables(), the facility for building a
321 nigel 25 set of character tables for a specific locale and using them instead of the
322 nigel 73 default tables. The tests make use of the "fr_FR" (French) locale. Before
323     running the test, the script checks for the presence of this locale by running
324     the "locale" command. If that command fails, or if it doesn't include "fr_FR"
325     in the list of available locales, the third test cannot be run, and a comment
326     is output to say why. If running this test produces instances of the error
327 nigel 25
328 nigel 73 ** Failed to set locale "fr_FR"
329 nigel 25
330     in the comparison output, it means that locale is not available on your system,
331     despite being listed by "locale". This does not mean that PCRE is broken.
332    
333 nigel 63 The fourth test checks the UTF-8 support. It is not run automatically unless
334     PCRE is built with UTF-8 support. To do this you must set --enable-utf8 when
335     running "configure". This file can be also fed directly to the perltest script,
336     provided you are running Perl 5.8 or higher. (For Perl 5.6, a small patch,
337     commented in the script, can be be used.)
338 nigel 3
339 nigel 75 The fifth test checks error handling with UTF-8 encoding, and internal UTF-8
340     features of PCRE that are not relevant to Perl.
341 nigel 3
342 nigel 77 The sixth and test checks the support for Unicode character properties. It it
343     not run automatically unless PCRE is built with Unicode property support. To to
344     this you must set --enable-unicode-properties when running "configure".
345 nigel 63
346 nigel 77 The seventh, eighth, and ninth tests check the pcre_dfa_exec() alternative
347     matching function, in non-UTF-8 mode, UTF-8 mode, and UTF-8 mode with Unicode
348     property support, respectively. The eighth and ninth tests are not run
349     automatically unless PCRE is build with the relevant support.
350 nigel 75
351 nigel 77
352 nigel 3 Character tables
353     ----------------
354    
355 nigel 75 PCRE uses four tables for manipulating and identifying characters whose values
356     are less than 256. The final argument of the pcre_compile() function is a
357     pointer to a block of memory containing the concatenated tables. A call to
358     pcre_maketables() can be used to generate a set of tables in the current
359     locale. If the final argument for pcre_compile() is passed as NULL, a set of
360     default tables that is built into the binary is used.
361 nigel 3
362 nigel 25 The source file called chartables.c contains the default set of tables. This is
363 nigel 27 not supplied in the distribution, but is built by the program dftables
364     (compiled from dftables.c), which uses the ANSI C character handling functions
365 nigel 25 such as isalnum(), isalpha(), isupper(), islower(), etc. to build the table
366 nigel 35 sources. This means that the default C locale which is set for your system will
367     control the contents of these default tables. You can change the default tables
368     by editing chartables.c and then re-building PCRE. If you do this, you should
369     probably also edit Makefile to ensure that the file doesn't ever get
370     re-generated.
371 nigel 3
372 nigel 25 The first two 256-byte tables provide lower casing and case flipping functions,
373     respectively. The next table consists of three 32-byte bit maps which identify
374     digits, "word" characters, and white space, respectively. These are used when
375     building 32-byte bit maps that represent character classes.
376    
377     The final 256-byte table has bits indicating various character types, as
378 nigel 3 follows:
379    
380     1 white space character
381     2 letter
382     4 decimal digit
383     8 hexadecimal digit
384     16 alphanumeric or '_'
385     128 regular expression metacharacter or binary zero
386    
387     You should not alter the set of characters that contain the 128 bit, as that
388     will cause PCRE to malfunction.
389    
390    
391 nigel 41 Manifest
392     --------
393 nigel 3
394 nigel 41 The distribution should contain the following files:
395 nigel 3
396 nigel 41 (A) The actual source files of the PCRE library functions and their
397     headers:
398 nigel 3
399 nigel 41 dftables.c auxiliary program for building chartables.c
400 nigel 75
401 nigel 41 pcreposix.c )
402 nigel 77 pcre_compile.c )
403     pcre_config.c )
404     pcre_dfa_exec.c )
405     pcre_exec.c )
406     pcre_fullinfo.c )
407     pcre_get.c ) sources for the functions in the library,
408     pcre_globals.c ) and some internal functions that they use
409     pcre_info.c )
410     pcre_maketables.c )
411     pcre_ord2utf8.c )
412     pcre_printint.c )
413     pcre_study.c )
414     pcre_tables.c )
415     pcre_try_flipped.c )
416     pcre_ucp_findchar.c )
417     pcre_valid_utf8.c )
418     pcre_version.c )
419     pcre_xclass.c )
420 nigel 75
421 nigel 77 ucp_findchar.c )
422 nigel 75 ucp.h ) source for the code that is used for
423     ucpinternal.h ) Unicode property handling
424     ucptable.c )
425     ucptypetable.c )
426    
427 nigel 43 pcre.in "source" for the header for the external API; pcre.h
428     is built from this by "configure"
429 nigel 41 pcreposix.h header for the external POSIX wrapper API
430 nigel 77 pcre_internal.h header for internal use
431 nigel 41 config.in template for config.h, which is built by configure
432 nigel 3
433 nigel 77 pcrecpp.h.in "source" for the header file for the C++ wrapper
434     pcrecpp.cc )
435     pcre_scanner.cc ) source for the C++ wrapper library
436    
437     pcre_stringpiece.h.in "source" for pcre_stringpiece.h, the header for the
438     C++ stringpiece functions
439     pcre_stringpiece.cc source for the C++ stringpiece functions
440    
441 nigel 41 (B) Auxiliary files:
442 nigel 3
443 nigel 41 AUTHORS information about the author of PCRE
444     ChangeLog log of changes to the code
445     INSTALL generic installation instructions
446     LICENCE conditions for the use of PCRE
447 nigel 43 COPYING the same, using GNU's standard name
448 nigel 41 Makefile.in template for Unix Makefile, which is built by configure
449     NEWS important changes in this release
450     NON-UNIX-USE notes on building PCRE on non-Unix systems
451     README this file
452 nigel 49 RunTest.in template for a Unix shell script for running tests
453 nigel 77 RunGrepTest.in template for a Unix shell script for pcregrep tests
454 nigel 41 config.guess ) files used by libtool,
455     config.sub ) used only when building a shared library
456     configure a configuring shell script (built by autoconf)
457     configure.in the autoconf input used to build configure
458     doc/Tech.Notes notes on the encoding
459 nigel 63 doc/*.3 man page sources for the PCRE functions
460     doc/*.1 man page sources for pcregrep and pcretest
461     doc/html/* HTML documentation
462     doc/pcre.txt plain text version of the man pages
463     doc/pcretest.txt plain text documentation of test program
464     doc/perltest.txt plain text documentation of Perl test program
465 nigel 41 install-sh a shell script for installing files
466 nigel 75 libpcre.pc.in "source" for libpcre.pc for pkg-config
467 nigel 53 ltmain.sh file used to build a libtool script
468 nigel 75 mkinstalldirs script for making install directories
469 nigel 53 pcretest.c comprehensive test program
470     pcredemo.c simple demonstration of coding calls to PCRE
471 nigel 41 perltest Perl test program
472 nigel 49 pcregrep.c source of a grep utility that uses PCRE
473 nigel 43 pcre-config.in source of script which retains PCRE information
474 nigel 77 pcrecpp_unittest.c )
475     pcre_scanner_unittest.c ) test programs for the C++ wrapper
476     pcre_stringpiece_unittest.c )
477     testdata/testinput* test data for main library tests
478     testdata/testoutput* expected test results
479     testdata/grep* input and output for pcregrep tests
480 nigel 3
481 nigel 41 (C) Auxiliary files for Win32 DLL
482 nigel 29
483 nigel 75 libpcre.def
484     libpcreposix.def
485 nigel 41 pcre.def
486 nigel 29
487 nigel 63 (D) Auxiliary file for VPASCAL
488    
489     makevp.bat
490    
491 nigel 77 Philip Hazel
492     Email local part: ph10
493     Email domain: cam.ac.uk
494 nigel 83 August 2005

webmaster@exim.org
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