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1  README file for PCRE (Perl-compatible regular expressions)  README file for PCRE (Perl-compatible regular expression library)
2  ----------------------------------------------------------  -----------------------------------------------------------------
3    
4  *******************************************************************************  The latest release of PCRE is always available from
 *           IMPORTANT FOR THOSE UPGRADING FROM VERSIONS BEFORE 2.00           *  
 *                                                                             *  
 * Please note that there has been a change in the API such that a larger      *  
 * ovector is required at matching time, to provide some additional workspace. *  
 * The new man page has details. This change was necessary in order to support *  
 * some of the new functionality in Perl 5.005.                                *  
 *                                                                             *  
 *           IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.00                   *  
 *                                                                             *  
 * Another (I hope this is the last!) change has been made to the API for the  *  
 * pcre_compile() function. An additional argument has been added to make it   *  
 * possible to pass over a pointer to character tables built in the current    *  
 * locale by pcre_maketables(). To use the default tables, this new arguement  *  
 * should be passed as NULL.                                                   *  
 *******************************************************************************  
5    
6  The distribution should contain the following files:    ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre-xxx.tar.gz
7    
8    Please read the NEWS file if you are upgrading from a previous release.
9    
10    PCRE has its own native API, but a set of "wrapper" functions that are based on
11    the POSIX API are also supplied in the library libpcreposix. Note that this
12    just provides a POSIX calling interface to PCRE: the regular expressions
13    themselves still follow Perl syntax and semantics. The header file
14    for the POSIX-style functions is called pcreposix.h. The official POSIX name is
15    regex.h, but I didn't want to risk possible problems with existing files of
16    that name by distributing it that way. To use it with an existing program that
17    uses the POSIX API, it will have to be renamed or pointed at by a link.
18    
19    
20    Building PCRE on a Unix system
21    ------------------------------
22    
23    To build PCRE on a Unix system, run the "configure" command in the PCRE
24    distribution directory. This is a standard GNU "autoconf" configuration script,
25    for which generic instructions are supplied in INSTALL. On many systems just
26    running "./configure" is sufficient, but the usual methods of changing standard
27    defaults are available. For example,
28    
29    CFLAGS='-O2 -Wall' ./configure --prefix=/opt/local
30    
31    specifies that the C compiler should be run with the flags '-O2 -Wall' instead
32    of the default, and that "make install" should install PCRE under /opt/local
33    instead of the default /usr/local.
34    
35    If you want to make use of the experimential, incomplete support for UTF-8
36    character strings in PCRE, you must add --enable-utf8 to the "configure"
37    command. Without it, the code for handling UTF-8 is not included in the
38    library. (Even when included, it still has to be enabled by an option at run
39    time.)
40    
41    The "configure" script builds four files:
42    
43    . Makefile is built by copying Makefile.in and making substitutions.
44    . config.h is built by copying config.in and making substitutions.
45    . pcre-config is built by copying pcre-config.in and making substitutions.
46    . RunTest is a script for running tests
47    
48    Once "configure" has run, you can run "make". It builds two libraries called
49    libpcre and libpcreposix, a test program called pcretest, and the pcregrep
50    command. You can use "make install" to copy these, and the public header file
51    pcre.h, to appropriate live directories on your system, in the normal way.
52    
53    Running "make install" also installs the command pcre-config, which can be used
54    to recall information about the PCRE configuration and installation. For
55    example,
56    
57      pcre-config --version
58    
59    prints the version number, and
60    
61     pcre-config --libs
62    
63    outputs information about where the library is installed. This command can be
64    included in makefiles for programs that use PCRE, saving the programmer from
65    having to remember too many details.
66    
   ChangeLog         log of changes to the code  
   Makefile          for building PCRE  
   README            this file  
   RunTest           a shell script for running tests  
   Tech.Notes        notes on the encoding  
   pcre.3            man page for the functions  
   pcreposix.3       man page for the POSIX wrapper API  
   deftables.c       auxiliary program for building chartables.c  
   maketables.c      )  
   study.c           ) source of  
   pcre.c            )   the functions  
   pcreposix.c       )  
   pcre.h            header for the external API  
   pcreposix.h       header for the external POSIX wrapper API  
   internal.h        header for internal use  
   pcretest.c        test program  
   pgrep.1           man page for pgrep  
   pgrep.c           source of a grep utility that uses PCRE  
   perltest          Perl test program  
   testinput         test data, compatible with Perl 5.004 and 5.005  
   testinput2        test data for error messages and non-Perl things  
   testinput3        test data, compatible with Perl 5.005  
   testinput4        test data for locale-specific tests  
   testoutput        test results corresponding to testinput  
   testoutput2       test results corresponding to testinput2  
   testoutput3       test results corresponding to testinput3  
   testoutput4       test results corresponding to testinput4  
   
 To build PCRE, edit Makefile for your system (it is a fairly simple make file,  
 and there are some comments at the top) and then run it. It builds two  
 libraries called libpcre.a and libpcreposix.a, a test program called pcretest,  
 and the pgrep command.  
   
 To test PCRE, run the RunTest script in the pcre directory. This runs pcretest  
 on each of the testinput files in turn, and compares the output with the  
 contents of the corresponding testoutput file. A file called testtry is used to  
 hold the output from pcretest (which is documented below).  
67    
68  To run pcretest on just one of the test files, give its number as an argument  Shared libraries on Unix systems
69  to RunTest, for example:  --------------------------------
70    
71    The default distribution builds PCRE as two shared libraries. This support is
72    new and experimental and may not work on all systems. It relies on the
73    "libtool" scripts - these are distributed with PCRE. It should build a
74    "libtool" script and use this to compile and link shared libraries, which are
75    placed in a subdirectory called .libs. The programs pcretest and pcregrep are
76    built to use these uninstalled libraries by means of wrapper scripts. When you
77    use "make install" to install shared libraries, pcregrep and pcretest are
78    automatically re-built to use the newly installed libraries. However, only
79    pcregrep is installed, as pcretest is really just a test program.
80    
81    To build PCRE using static libraries you must use --disable-shared when
82    configuring it. For example
83    
84    ./configure --prefix=/usr/gnu --disable-shared
85    
86    Then run "make" in the usual way.
87    
88    
89    Building on non-Unix systems
90    ----------------------------
91    
92    For a non-Unix system, read the comments in the file NON-UNIX-USE. PCRE has
93    been compiled on Windows systems and on Macintoshes, but I don't know the
94    details because I don't use those systems. It should be straightforward to
95    build PCRE on any system that has a Standard C compiler, because it uses only
96    Standard C functions.
97    
98    
99    Testing PCRE
100    ------------
101    
102    To test PCRE on a Unix system, run the RunTest script in the pcre directory.
103    (This can also be run by "make runtest", "make check", or "make test".) For
104    other systems, see the instruction in NON-UNIX-USE.
105    
106    The script runs the pcretest test program (which is documented in
107    doc/pcretest.txt) on each of the testinput files (in the testdata directory) in
108    turn, and compares the output with the contents of the corresponding testoutput
109    file. A file called testtry is used to hold the output from pcretest. To run
110    pcretest on just one of the test files, give its number as an argument to
111    RunTest, for example:
112    
113    RunTest 3    RunTest 3
114    
115  The first and third test files can also be fed directly into the perltest  The first and third test files can also be fed directly into the perltest
116  program to check that Perl gives the same results. The third file requires the  script to check that Perl gives the same results. The third file requires the
117  additional features of release 5.005, which is why it is kept separate from the  additional features of release 5.005, which is why it is kept separate from the
118  main test input, which needs only Perl 5.004. In the long run, when 5.005 is  main test input, which needs only Perl 5.004. In the long run, when 5.005 (or
119  widespread, these two test files may get amalgamated.  higher) is widespread, these two test files may get amalgamated.
120    
121  The second set of tests check pcre_info(), pcre_study(), error detection and  The second set of tests check pcre_fullinfo(), pcre_info(), pcre_study(),
122  run-time flags that are specific to PCRE, as well as the POSIX wrapper API.  pcre_copy_substring(), pcre_get_substring(), pcre_get_substring_list(), error
123    detection, and run-time flags that are specific to PCRE, as well as the POSIX
124    wrapper API. It also uses the debugging flag to check some of the internals of
125    pcre_compile().
126    
127    If you build PCRE with a locale setting that is not the standard C locale, the
128    character tables may be different (see next paragraph). In some cases, this may
129    cause failures in the second set of tests. For example, in a locale where the
130    isprint() function yields TRUE for characters in the range 128-255, the use of
131    [:isascii:] inside a character class defines a different set of characters, and
132    this shows up in this test as a difference in the compiled code, which is being
133    listed for checking. Where the comparison test output contains [\x00-\x7f] the
134    test will contain [\x00-\xff], and similarly in some other cases. This is not a
135    bug in PCRE.
136    
137  The fourth set of tests checks pcre_maketables(), the facility for building a  The fourth set of tests checks pcre_maketables(), the facility for building a
138  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
# Line 85  output to say why. If running this test Line 147  output to say why. If running this test
147  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,
148  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.
149    
150  To install PCRE, copy libpcre.a to any suitable library directory (e.g.  The fifth test checks the experimental, incomplete UTF-8 support. It is not run
151  /usr/local/lib), pcre.h to any suitable include directory (e.g.  automatically unless PCRE is built with UTF-8 support. This file can be fed
152  /usr/local/include), and pcre.3 to any suitable man directory (e.g.  directly to the perltest8 script, which requires Perl 5.6 or higher. The sixth
153  /usr/local/man/man3).  file tests internal UTF-8 features of PCRE that are not relevant to Perl.
   
 To install the pgrep command, copy it to any suitable binary directory, (e.g.  
 /usr/local/bin) and pgrep.1 to any suitable man directory (e.g.  
 /usr/local/man/man1).  
   
 PCRE has its own native API, but a set of "wrapper" functions that are based on  
 the POSIX API are also supplied in the library libpcreposix.a. Note that this  
 just provides a POSIX calling interface to PCRE: the regular expressions  
 themselves still follow Perl syntax and semantics. The header file  
 for the POSIX-style functions is called pcreposix.h. The official POSIX name is  
 regex.h, but I didn't want to risk possible problems with existing files of  
 that name by distributing it that way. To use it with an existing program that  
 uses the POSIX API, it will have to be renamed or pointed at by a link.  
154    
155    
156  Character tables  Character tables
# Line 109  Character tables Line 158  Character tables
158    
159  PCRE uses four tables for manipulating and identifying characters. The final  PCRE uses four tables for manipulating and identifying characters. The final
160  argument of the pcre_compile() function is a pointer to a block of memory  argument of the pcre_compile() function is a pointer to a block of memory
161  containing the concatenated tables. A call to pcre_maketables() is used to  containing the concatenated tables. A call to pcre_maketables() can be used to
162  generate a set of tables in the current locale. However, if the final argument  generate a set of tables in the current locale. If the final argument for
163  is passed as NULL, a set of default tables that is built into the binary is  pcre_compile() is passed as NULL, a set of default tables that is built into
164  used.  the binary is used.
165    
166  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
167  not supplied in the distribution, but is built by the program deftables  not supplied in the distribution, but is built by the program dftables
168  (compiled from deftables.c), which uses the ANSI C character handling functions  (compiled from dftables.c), which uses the ANSI C character handling functions
169  such as isalnum(), isalpha(), isupper(), islower(), etc. to build the table  such as isalnum(), isalpha(), isupper(), islower(), etc. to build the table
170  sources. This means that the default C locale set your system will control the  sources. This means that the default C locale which is set for your system will
171  contents of the tables. You can change the default tables by editing  control the contents of these default tables. You can change the default tables
172  chartables.c and then re-building PCRE. If you do this, you should probably  by editing chartables.c and then re-building PCRE. If you do this, you should
173  also edit Makefile to ensure that the file doesn't ever get re-generated.  probably also edit Makefile to ensure that the file doesn't ever get
174    re-generated.
175    
176  The first two 256-byte tables provide lower casing and case flipping functions,  The first two 256-byte tables provide lower casing and case flipping functions,
177  respectively. The next table consists of three 32-byte bit maps which identify  respectively. The next table consists of three 32-byte bit maps which identify
# Line 142  You should not alter the set of characte Line 192  You should not alter the set of characte
192  will cause PCRE to malfunction.  will cause PCRE to malfunction.
193    
194    
195  The pcretest program  Manifest
196  --------------------  --------
197    
198    The distribution should contain the following files:
199    
200    (A) The actual source files of the PCRE library functions and their
201        headers:
202    
203      dftables.c            auxiliary program for building chartables.c
204      get.c                 )
205      maketables.c          )
206      study.c               ) source of
207      pcre.c                )   the functions
208      pcreposix.c           )
209      pcre.in               "source" for the header for the external API; pcre.h
210                              is built from this by "configure"
211      pcreposix.h           header for the external POSIX wrapper API
212      internal.h            header for internal use
213      config.in             template for config.h, which is built by configure
214    
215    (B) Auxiliary files:
216    
217      AUTHORS               information about the author of PCRE
218      ChangeLog             log of changes to the code
219      INSTALL               generic installation instructions
220      LICENCE               conditions for the use of PCRE
221      COPYING               the same, using GNU's standard name
222      Makefile.in           template for Unix Makefile, which is built by configure
223      NEWS                  important changes in this release
224      NON-UNIX-USE          notes on building PCRE on non-Unix systems
225      README                this file
226      RunTest.in            template for a Unix shell script for running tests
227      config.guess          ) files used by libtool,
228      config.sub            )   used only when building a shared library
229      configure             a configuring shell script (built by autoconf)
230      configure.in          the autoconf input used to build configure
231      doc/Tech.Notes        notes on the encoding
232      doc/pcre.3            man page source for the PCRE functions
233      doc/pcre.html         HTML version
234      doc/pcre.txt          plain text version
235      doc/pcreposix.3       man page source for the POSIX wrapper API
236      doc/pcreposix.html    HTML version
237      doc/pcreposix.txt     plain text version
238      doc/pcretest.txt      documentation of test program
239      doc/perltest.txt      documentation of Perl test program
240      doc/pcregrep.1        man page source for the pcregrep utility
241      doc/pcregrep.html     HTML version
242      doc/pcregrep.txt      plain text version
243      install-sh            a shell script for installing files
244      ltconfig              ) files used to build "libtool",
245      ltmain.sh             )   used only when building a shared library
246      pcretest.c            test program
247      perltest              Perl test program
248      perltest8             Perl test program for UTF-8 tests
249      pcregrep.c            source of a grep utility that uses PCRE
250      pcre-config.in        source of script which retains PCRE information
251      testdata/testinput1   test data, compatible with Perl 5.004 and 5.005
252      testdata/testinput2   test data for error messages and non-Perl things
253      testdata/testinput3   test data, compatible with Perl 5.005
254      testdata/testinput4   test data for locale-specific tests
255      testdata/testinput5   test data for UTF-8 tests compatible with Perl 5.6
256      testdata/testinput6   test data for other UTF-8 tests
257      testdata/testoutput1  test results corresponding to testinput1
258      testdata/testoutput2  test results corresponding to testinput2
259      testdata/testoutput3  test results corresponding to testinput3
260      testdata/testoutput4  test results corresponding to testinput4
261      testdata/testoutput5  test results corresponding to testinput5
262      testdata/testoutput6  test results corresponding to testinput6
263    
264  This program is intended for testing PCRE, but it can also be used for  (C) Auxiliary files for Win32 DLL
 experimenting with regular expressions.  
265    
266  If it is given two filename arguments, it reads from the first and writes to    dll.mk
267  the second. If it is given only one filename argument, it reads from that file    pcre.def
 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, for example  
   
   /(a|bc)x+yz/  
   
 and may be followed by i, m, s, or x to set the PCRE_CASELESS, PCRE_MULTILINE,  
 PCRE_DOTALL, or PCRE_EXTENDED options, respectively. These options have the  
 same effect as they do in Perl.  
   
 There are also some upper case options that do not match Perl options: /A, /E,  
 and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.  
   
 The /L option must be followed directly by the name of a locale, for example,  
   
   /pattern/Lfr  
   
 For this reason, it must be the last option letter. The given locale is set,  
 pcre_maketables() is called to build a set of character tables for the locale,  
 and this is then passed to pcre_compile() when compiling the regular  
 expression. Without an /L option, NULL is passed as the tables pointer; that  
 is, /L applies only to the expression on which it appears.  
   
 The /I option requests that pcretest output information about the compiled  
 expression (whether it is anchored, has a fixed first character, and so on). It  
 does this by calling pcre_info() after compiling an expression, and outputting  
 the information it gets back. If the pattern is studied, the results of that  
 are also output.  
   
 The /D option is a PCRE debugging feature, which also assumes /I. It causes the  
 internal form of compiled regular expressions to be output after compilation.  
   
 The /S option causes pcre_study() to be called after the expression has been  
 compiled, and the results used when the expression is matched.  
   
 Finally, the /P option causes pcretest to call PCRE via the POSIX wrapper API  
 rather than its native API. When this is done, all other options except /i and  
 /m are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is set if /m  
 is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always, and  
 PCRE_DOTALL unless REG_NEWLINE is set.  
   
 A regular expression can extend over several lines of input; the newlines are  
 included in it. See the testinput files for many examples.  
   
 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()  
   \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 identified substrings that  
 pcre_exec() returns, starting with number 0 for the string that matched the  
 whole pattern. Here is an example of an interactive pcretest run.  
   
   $ pcretest  
   Testing Perl-Compatible Regular Expressions  
   PCRE version 0.90 08-Sep-1997  
   
     re> /^abc(\d+)/  
   data> abc123  
     0: abc123  
     1: 123  
   data> xyz  
   No match  
   
 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 -s is given to pcretest, it outputs the size of each compiled  
 pattern after it has been compiled.  
   
 If the -t option is given, each compile, study, and match is run 10000 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  
 10000 times and the timing will be distorted. If you want to change the number  
 of repetitions used for timing, edit the definition of LOOPREPEAT at the top of  
 pcretest.c  
   
   
   
 The perltest program  
 --------------------  
   
 The perltest program tests Perl's regular expressions; it has the same  
 specification as pcretest, and so can be given identical input, except that  
 input patterns can be followed only by Perl's lower case options. The contents  
 of testinput and testinput3 meet this condition.  
   
 The data lines are processed as Perl strings, so if they contain $ or @  
 characters, these have to be escaped. For this reason, all such characters in  
 the testinput file are escaped so that it can be used for perltest as well as  
 for pcretest, and the special upper case options such as /A that pcretest  
 recognizes are not used in this file. The output should be identical, apart  
 from the initial identifying banner.  
   
 The testinput2 and testinput4 files are not suitable for feeding to Perltest,  
 since they do make use of the special upper case options and escapes that  
 pcretest uses to test some features of PCRE. The first of these files also  
 contains malformed regular expressions, in order to check that PCRE diagnoses  
 them correctly.  
268    
269  Philip Hazel <ph10@cam.ac.uk>  Philip Hazel <ph10@cam.ac.uk>
270  October 1998  August 2000

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