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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
6     ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.tar.gz
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     -------------
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).
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.
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     ----------------------
36     If you install PCRE in the normal way, you will end up with an installed set of
37 nigel 91 man pages whose names all start with "pcre". The one that is just called "pcre"
38 nigel 75 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:
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.
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.
55 nigel 53 Contributions by users of PCRE
56     ------------------------------
58     You can find contributions from PCRE users in the directory
60     ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/Contrib
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.
68 nigel 63 Building PCRE on a Unix-like system
69     -----------------------------------
70 nigel 3
71 nigel 87 If you are using HP's ANSI C++ compiler (aCC), please see the special note
72     in the section entitled "Using HP's ANSI C++ compiler (aCC)" below.
74 nigel 63 To build PCRE on a Unix-like system, first run the "configure" command from the
75     PCRE distribution directory, with your current directory set to the directory
76     where you want the files to be created. This command is a standard GNU
77     "autoconf" configuration script, for which generic instructions are supplied in
78     INSTALL.
79 nigel 3
80 nigel 53 Most commonly, people build PCRE within its own distribution directory, and in
81     this case, on many systems, just running "./configure" is sufficient, but the
82 nigel 75 usual methods of changing standard defaults are available. For example:
83 nigel 53
84 nigel 41 CFLAGS='-O2 -Wall' ./configure --prefix=/opt/local
86     specifies that the C compiler should be run with the flags '-O2 -Wall' instead
87     of the default, and that "make install" should install PCRE under /opt/local
88 nigel 49 instead of the default /usr/local.
89 nigel 41
90 nigel 53 If you want to build in a different directory, just run "configure" with that
91     directory as current. For example, suppose you have unpacked the PCRE source
92     into /source/pcre/pcre-xxx, but you want to build it in /build/pcre/pcre-xxx:
94     cd /build/pcre/pcre-xxx
95     /source/pcre/pcre-xxx/configure
97 nigel 87 PCRE is written in C and is normally compiled as a C library. However, it is
98     possible to build it as a C++ library, though the provided building apparatus
99     does not have any features to support this.
101 nigel 63 There are some optional features that can be included or omitted from the PCRE
102     library. You can read more about them in the pcrebuild man page.
103 nigel 49
104 nigel 83 . If you want to suppress the building of the C++ wrapper library, you can add
105     --disable-cpp to the "configure" command. Otherwise, when "configure" is run,
106     will try to find a C++ compiler and C++ header files, and if it succeeds, it
107     will try to build the C++ wrapper.
109 nigel 63 . If you want to make use of the support for UTF-8 character strings in PCRE,
110     you must add --enable-utf8 to the "configure" command. Without it, the code
111     for handling UTF-8 is not included in the library. (Even when included, it
112     still has to be enabled by an option at run time.)
114 nigel 75 . If, in addition to support for UTF-8 character strings, you want to include
115     support for the \P, \p, and \X sequences that recognize Unicode character
116     properties, you must add --enable-unicode-properties to the "configure"
117 nigel 91 command. This adds about 30K to the size of the library (in the form of a
118 nigel 75 property table); only the basic two-letter properties such as Lu are
119     supported.
121 nigel 93 . You can build PCRE to recognize either CR or LF or the sequence CRLF or any
122     of the Unicode newline sequences as indicating the end of a line. Whatever
123     you specify at build time is the default; the caller of PCRE can change the
124     selection at run time. The default newline indicator is a single LF character
125     (the Unix standard). You can specify the default newline indicator by adding
126     --newline-is-cr or --newline-is-lf or --newline-is-crlf or --newline-is-any
127     to the "configure" command, respectively.
128 nigel 63
129     . When called via the POSIX interface, PCRE uses malloc() to get additional
130     storage for processing capturing parentheses if there are more than 10 of
131     them. You can increase this threshold by setting, for example,
133     --with-posix-malloc-threshold=20
135     on the "configure" command.
137 nigel 77 . PCRE has a counter that can be set to limit the amount of resources it uses.
138 nigel 63 If the limit is exceeded during a match, the match fails. The default is ten
139     million. You can change the default by setting, for example,
141     --with-match-limit=500000
143     on the "configure" command. This is just the default; individual calls to
144     pcre_exec() can supply their own value. There is discussion on the pcreapi
145     man page.
147 nigel 91 . There is a separate counter that limits the depth of recursive function calls
148     during a matching process. This also has a default of ten million, which is
149     essentially "unlimited". You can change the default by setting, for example,
151     --with-match-limit-recursion=500000
153     Recursive function calls use up the runtime stack; running out of stack can
154     cause programs to crash in strange ways. There is a discussion about stack
155     sizes in the pcrestack man page.
157 nigel 63 . The default maximum compiled pattern size is around 64K. You can increase
158     this by adding --with-link-size=3 to the "configure" command. You can
159     increase it even more by setting --with-link-size=4, but this is unlikely
160     ever to be necessary. If you build PCRE with an increased link size, test 2
161     (and 5 if you are using UTF-8) will fail. Part of the output of these tests
162     is a representation of the compiled pattern, and this changes with the link
163     size.
165 nigel 77 . You can build PCRE so that its internal match() function that is called from
166     pcre_exec() does not call itself recursively. Instead, it uses blocks of data
167     from the heap via special functions pcre_stack_malloc() and pcre_stack_free()
168     to save data that would otherwise be saved on the stack. To build PCRE like
169     this, use
170 nigel 73
171     --disable-stack-for-recursion
173     on the "configure" command. PCRE runs more slowly in this mode, but it may be
174 nigel 77 necessary in environments with limited stack sizes. This applies only to the
175     pcre_exec() function; it does not apply to pcre_dfa_exec(), which does not
176     use deeply nested recursion.
177 nigel 73
178 nigel 77 The "configure" script builds eight files for the basic C library:
179 nigel 49
180 nigel 77 . Makefile is the makefile that builds the library
181     . config.h contains build-time configuration options for the library
182     . pcre-config is a script that shows the settings of "configure" options
183     . libpcre.pc is data for the pkg-config command
184 nigel 75 . libtool is a script that builds shared and/or static libraries
185 nigel 77 . RunTest is a script for running tests on the library
186     . RunGrepTest is a script for running tests on the pcregrep command
187 nigel 41
188 nigel 77 In addition, if a C++ compiler is found, the following are also built:
190     . pcrecpp.h is the header file for programs that call PCRE via the C++ wrapper
191     . pcre_stringpiece.h is the header for the C++ "stringpiece" functions
193     The "configure" script also creates config.status, which is an executable
194     script that can be run to recreate the configuration, and config.log, which
195     contains compiler output from tests that "configure" runs.
197     Once "configure" has run, you can run "make". It builds two libraries, called
198 nigel 49 libpcre and libpcreposix, a test program called pcretest, and the pcregrep
199 nigel 77 command. If a C++ compiler was found on your system, it also builds the C++
200     wrapper library, which is called libpcrecpp, and some test programs called
201     pcrecpp_unittest, pcre_scanner_unittest, and pcre_stringpiece_unittest.
202 nigel 3
203 nigel 77 The command "make test" runs all the appropriate tests. Details of the PCRE
204     tests are given in a separate section of this document, below.
205 nigel 75
206 nigel 77 You can use "make install" to copy the libraries, the public header files
207     pcre.h, pcreposix.h, pcrecpp.h, and pcre_stringpiece.h (the last two only if
208     the C++ wrapper was built), and the man pages to appropriate live directories
209     on your system, in the normal way.
211     If you want to remove PCRE from your system, you can run "make uninstall".
212     This removes all the files that "make install" installed. However, it does not
213     remove any directories, because these are often shared with other programs.
216 nigel 75 Retrieving configuration information on Unix-like systems
217     ---------------------------------------------------------
219 nigel 43 Running "make install" also installs the command pcre-config, which can be used
220     to recall information about the PCRE configuration and installation. For
221 nigel 75 example:
222 nigel 37
223 nigel 43 pcre-config --version
225     prints the version number, and
227 nigel 75 pcre-config --libs
228 nigel 43
229     outputs information about where the library is installed. This command can be
230     included in makefiles for programs that use PCRE, saving the programmer from
231     having to remember too many details.
233 nigel 75 The pkg-config command is another system for saving and retrieving information
234     about installed libraries. Instead of separate commands for each library, a
235     single command is used. For example:
236 nigel 43
237 nigel 75 pkg-config --cflags pcre
239     The data is held in *.pc files that are installed in a directory called
240     pkgconfig.
243 nigel 63 Shared libraries on Unix-like systems
244     -------------------------------------
245 nigel 53
246 nigel 77 The default distribution builds PCRE as shared libraries and static libraries,
247     as long as the operating system supports shared libraries. Shared library
248     support relies on the "libtool" script which is built as part of the
249 nigel 53 "configure" process.
250 nigel 39
251 nigel 53 The libtool script is used to compile and link both shared and static
252     libraries. They are placed in a subdirectory called .libs when they are newly
253     built. The programs pcretest and pcregrep are built to use these uninstalled
254     libraries (by means of wrapper scripts in the case of shared libraries). When
255     you use "make install" to install shared libraries, pcregrep and pcretest are
256     automatically re-built to use the newly installed shared libraries before being
257     installed themselves. However, the versions left in the source directory still
258     use the uninstalled libraries.
260     To build PCRE using static libraries only you must use --disable-shared when
261 nigel 75 configuring it. For example:
262 nigel 3
263 nigel 43 ./configure --prefix=/usr/gnu --disable-shared
264 nigel 41
265 nigel 53 Then run "make" in the usual way. Similarly, you can use --disable-static to
266     build only shared libraries.
267 nigel 41
268 nigel 43
269 nigel 63 Cross-compiling on a Unix-like system
270     -------------------------------------
272     You can specify CC and CFLAGS in the normal way to the "configure" command, in
273     order to cross-compile PCRE for some other host. However, during the building
274     process, the dftables.c source file is compiled *and run* on the local host, in
275     order to generate the default character tables (the chartables.c file). It
276     therefore needs to be compiled with the local compiler, not the cross compiler.
277 nigel 77 You can do this by specifying CC_FOR_BUILD (and if necessary CFLAGS_FOR_BUILD;
278     there are also CXX_FOR_BUILD and CXXFLAGS_FOR_BUILD for the C++ wrapper)
279 nigel 73 when calling the "configure" command. If they are not specified, they default
280     to the values of CC and CFLAGS.
281 nigel 63
283 nigel 87 Using HP's ANSI C++ compiler (aCC)
284     ----------------------------------
286 nigel 93 Unless C++ support is disabled by specifying the "--disable-cpp" option of the
287 nigel 87 "configure" script, you *must* include the "-AA" option in the CXXFLAGS
288     environment variable in order for the C++ components to compile correctly.
290     Also, note that the aCC compiler on PA-RISC platforms may have a defect whereby
291     needed libraries fail to get included when specifying the "-AA" compiler
292     option. If you experience unresolved symbols when linking the C++ programs,
293     use the workaround of specifying the following environment variable prior to
294     running the "configure" script:
296     CXXLDFLAGS="-lstd_v2 -lCsup_v2"
299 nigel 41 Building on non-Unix systems
300     ----------------------------
302 nigel 73 For a non-Unix system, read the comments in the file NON-UNIX-USE, though if
303     the system supports the use of "configure" and "make" you may be able to build
304     PCRE in the same way as for Unix systems.
306     PCRE has been compiled on Windows systems and on Macintoshes, but I don't know
307     the details because I don't use those systems. It should be straightforward to
308 nigel 93 build PCRE on any system that has a Standard C compiler and library, because it
309     uses only Standard C functions.
310 nigel 41
312     Testing PCRE
313     ------------
315 nigel 53 To test PCRE on a Unix system, run the RunTest script that is created by the
316 nigel 77 configuring process. There is also a script called RunGrepTest that tests the
317     options of the pcregrep command. If the C++ wrapper library is build, three
318     test programs called pcrecpp_unittest, pcre_scanner_unittest, and
319     pcre_stringpiece_unittest are provided.
320 nigel 41
321 nigel 77 Both the scripts and all the program tests are run if you obey "make runtest",
322     "make check", or "make test". For other systems, see the instructions in
323     NON-UNIX-USE.
325     The RunTest script runs the pcretest test program (which is documented in its
326     own man page) on each of the testinput files (in the testdata directory) in
327     turn, and compares the output with the contents of the corresponding testoutput
328 nigel 93 files. A file called testtry is used to hold the main output from pcretest
329 nigel 75 (testsavedregex is also used as a working file). To run pcretest on just one of
330     the test files, give its number as an argument to RunTest, for example:
331 nigel 41
332 nigel 63 RunTest 2
333 nigel 3
334 nigel 93 The first test file can also be fed directly into the perltest script to check
335     that Perl gives the same results. The only difference you should see is in the
336     first few lines, where the Perl version is given instead of the PCRE version.
337 nigel 3
338 nigel 49 The second set of tests check pcre_fullinfo(), pcre_info(), pcre_study(),
339     pcre_copy_substring(), pcre_get_substring(), pcre_get_substring_list(), error
340     detection, and run-time flags that are specific to PCRE, as well as the POSIX
341     wrapper API. It also uses the debugging flag to check some of the internals of
342     pcre_compile().
343 nigel 7
344 nigel 49 If you build PCRE with a locale setting that is not the standard C locale, the
345     character tables may be different (see next paragraph). In some cases, this may
346     cause failures in the second set of tests. For example, in a locale where the
347     isprint() function yields TRUE for characters in the range 128-255, the use of
348     [:isascii:] inside a character class defines a different set of characters, and
349     this shows up in this test as a difference in the compiled code, which is being
350     listed for checking. Where the comparison test output contains [\x00-\x7f] the
351     test will contain [\x00-\xff], and similarly in some other cases. This is not a
352     bug in PCRE.
354 nigel 63 The third set of tests checks pcre_maketables(), the facility for building a
355 nigel 25 set of character tables for a specific locale and using them instead of the
356 nigel 73 default tables. The tests make use of the "fr_FR" (French) locale. Before
357     running the test, the script checks for the presence of this locale by running
358     the "locale" command. If that command fails, or if it doesn't include "fr_FR"
359     in the list of available locales, the third test cannot be run, and a comment
360     is output to say why. If running this test produces instances of the error
361 nigel 25
362 nigel 73 ** Failed to set locale "fr_FR"
363 nigel 25
364     in the comparison output, it means that locale is not available on your system,
365     despite being listed by "locale". This does not mean that PCRE is broken.
367 nigel 63 The fourth test checks the UTF-8 support. It is not run automatically unless
368     PCRE is built with UTF-8 support. To do this you must set --enable-utf8 when
369     running "configure". This file can be also fed directly to the perltest script,
370     provided you are running Perl 5.8 or higher. (For Perl 5.6, a small patch,
371     commented in the script, can be be used.)
372 nigel 3
373 nigel 75 The fifth test checks error handling with UTF-8 encoding, and internal UTF-8
374     features of PCRE that are not relevant to Perl.
375 nigel 3
376 nigel 77 The sixth and test checks the support for Unicode character properties. It it
377     not run automatically unless PCRE is built with Unicode property support. To to
378     this you must set --enable-unicode-properties when running "configure".
379 nigel 63
380 nigel 77 The seventh, eighth, and ninth tests check the pcre_dfa_exec() alternative
381     matching function, in non-UTF-8 mode, UTF-8 mode, and UTF-8 mode with Unicode
382     property support, respectively. The eighth and ninth tests are not run
383     automatically unless PCRE is build with the relevant support.
384 nigel 75
385 nigel 77
386 nigel 3 Character tables
387     ----------------
389 nigel 75 PCRE uses four tables for manipulating and identifying characters whose values
390     are less than 256. The final argument of the pcre_compile() function is a
391     pointer to a block of memory containing the concatenated tables. A call to
392     pcre_maketables() can be used to generate a set of tables in the current
393     locale. If the final argument for pcre_compile() is passed as NULL, a set of
394     default tables that is built into the binary is used.
395 nigel 3
396 nigel 25 The source file called chartables.c contains the default set of tables. This is
397 nigel 27 not supplied in the distribution, but is built by the program dftables
398     (compiled from dftables.c), which uses the ANSI C character handling functions
399 nigel 25 such as isalnum(), isalpha(), isupper(), islower(), etc. to build the table
400 nigel 35 sources. This means that the default C locale which is set for your system will
401     control the contents of these default tables. You can change the default tables
402     by editing chartables.c and then re-building PCRE. If you do this, you should
403     probably also edit Makefile to ensure that the file doesn't ever get
404     re-generated.
405 nigel 3
406 nigel 25 The first two 256-byte tables provide lower casing and case flipping functions,
407     respectively. The next table consists of three 32-byte bit maps which identify
408     digits, "word" characters, and white space, respectively. These are used when
409     building 32-byte bit maps that represent character classes.
411     The final 256-byte table has bits indicating various character types, as
412 nigel 3 follows:
414     1 white space character
415     2 letter
416     4 decimal digit
417     8 hexadecimal digit
418     16 alphanumeric or '_'
419     128 regular expression metacharacter or binary zero
421     You should not alter the set of characters that contain the 128 bit, as that
422     will cause PCRE to malfunction.
425 nigel 41 Manifest
426     --------
427 nigel 3
428 nigel 41 The distribution should contain the following files:
429 nigel 3
430 nigel 41 (A) The actual source files of the PCRE library functions and their
431     headers:
432 nigel 3
433 nigel 41 dftables.c auxiliary program for building chartables.c
434 nigel 75
435 nigel 41 pcreposix.c )
436 nigel 77 pcre_compile.c )
437     pcre_config.c )
438     pcre_dfa_exec.c )
439     pcre_exec.c )
440     pcre_fullinfo.c )
441     pcre_get.c ) sources for the functions in the library,
442     pcre_globals.c ) and some internal functions that they use
443     pcre_info.c )
444     pcre_maketables.c )
445 nigel 93 pcre_newline.c )
446 nigel 77 pcre_ord2utf8.c )
447 nigel 91 pcre_refcount.c )
448 nigel 77 pcre_study.c )
449     pcre_tables.c )
450     pcre_try_flipped.c )
451 nigel 91 pcre_ucp_searchfuncs.c)
452 nigel 77 pcre_valid_utf8.c )
453     pcre_version.c )
454     pcre_xclass.c )
455 nigel 75 ucptable.c )
457 nigel 91 pcre_printint.src ) debugging function that is #included in pcretest, and
458     ) can also be #included in pcre_compile()
460     pcre.h the public PCRE header file
461 nigel 41 pcreposix.h header for the external POSIX wrapper API
462 nigel 77 pcre_internal.h header for internal use
463 nigel 91 ucp.h ) headers concerned with
464     ucpinternal.h ) Unicode property handling
465 nigel 41 config.in template for config.h, which is built by configure
466 nigel 3
467 nigel 87 pcrecpp.h the header file for the C++ wrapper
468     pcrecpparg.h.in "source" for another C++ header file
469 nigel 77 pcrecpp.cc )
470     pcre_scanner.cc ) source for the C++ wrapper library
472     pcre_stringpiece.h.in "source" for pcre_stringpiece.h, the header for the
473     C++ stringpiece functions
474     pcre_stringpiece.cc source for the C++ stringpiece functions
476 nigel 41 (B) Auxiliary files:
477 nigel 3
478 nigel 41 AUTHORS information about the author of PCRE
479     ChangeLog log of changes to the code
480     INSTALL generic installation instructions
481     LICENCE conditions for the use of PCRE
482 nigel 43 COPYING the same, using GNU's standard name
483 nigel 41 Makefile.in template for Unix Makefile, which is built by configure
484     NEWS important changes in this release
485     NON-UNIX-USE notes on building PCRE on non-Unix systems
486     README this file
487 nigel 49 RunTest.in template for a Unix shell script for running tests
488 nigel 77 RunGrepTest.in template for a Unix shell script for pcregrep tests
489 nigel 41 config.guess ) files used by libtool,
490     config.sub ) used only when building a shared library
491 nigel 91 config.h.in "source" for the config.h header file
492 nigel 41 configure a configuring shell script (built by autoconf)
493 nigel 91 configure.ac the autoconf input used to build configure
494 nigel 41 doc/Tech.Notes notes on the encoding
495 nigel 63 doc/*.3 man page sources for the PCRE functions
496     doc/*.1 man page sources for pcregrep and pcretest
497     doc/html/* HTML documentation
498     doc/pcre.txt plain text version of the man pages
499     doc/pcretest.txt plain text documentation of test program
500     doc/perltest.txt plain text documentation of Perl test program
501 nigel 41 install-sh a shell script for installing files
502 nigel 75 libpcre.pc.in "source" for libpcre.pc for pkg-config
503 nigel 53 ltmain.sh file used to build a libtool script
504 nigel 75 mkinstalldirs script for making install directories
505 nigel 53 pcretest.c comprehensive test program
506     pcredemo.c simple demonstration of coding calls to PCRE
507 nigel 41 perltest Perl test program
508 nigel 49 pcregrep.c source of a grep utility that uses PCRE
509 nigel 43 pcre-config.in source of script which retains PCRE information
510 nigel 77 pcrecpp_unittest.c )
511     pcre_scanner_unittest.c ) test programs for the C++ wrapper
512     pcre_stringpiece_unittest.c )
513     testdata/testinput* test data for main library tests
514     testdata/testoutput* expected test results
515     testdata/grep* input and output for pcregrep tests
516 nigel 3
517 nigel 41 (C) Auxiliary files for Win32 DLL
518 nigel 29
519 nigel 75 libpcre.def
520     libpcreposix.def
521 nigel 29
522 nigel 63 (D) Auxiliary file for VPASCAL
524     makevp.bat
526 nigel 77 Philip Hazel
527     Email local part: ph10
528     Email domain: cam.ac.uk
529 nigel 93 November 2006

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