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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  *******************************************************************************  Please read the NEWS file if you are upgrading from a previous release.
 *           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    
7  The distribution should contain the following files:  Building PCRE on a Unix system
8    ------------------------------
9    
10    To build PCRE on a Unix system, run the "configure" command in the PCRE
11    distribution directory. This is a standard GNU "autoconf" configuration script,
12    for which generic instructions are supplied in INSTALL. On many systems just
13    running "./configure" is sufficient, but the usual methods of changing standard
14    defaults are available. For example
15    
16    CFLAGS='-O2 -Wall' ./configure --prefix=/opt/local
17    
18    specifies that the C compiler should be run with the flags '-O2 -Wall' instead
19    of the default, and that "make install" should install PCRE under /opt/local
20    instead of the default /usr/local. The "configure" script builds two files:
21    
22    . Makefile is built by copying Makefile.in and making certain substitutions.
23    . config.h is built by copying config.in and making certain substitutions.
24    
25    Once "configure" has run, you can run "make". It builds two libraries called
26    libpcre.a and libpcreposix.a, a test program called pcretest, and the pgrep
27    command. You can use "make install" to copy these, and the public header file
28    pcre.h, to appropriate live directories on your system, in the normal way.
29    
30    
31    Shared libraries on Unix systems
32    --------------------------------
33    
34    The default distribution builds static libraries. It is also possible to build
35    PCRE as two shared libraries. This support is new and experimental and may not
36    work on all systems. It relies on the "libtool" scripts - these are distributed
37    with PCRE. To build PCRE using shared libraries you must use --enable-shared
38    when configuring it. For example
39    
40    ./configure --prefix=/usr/gnu --enable-shared
41    
42    Then run "make" in the usual way. It should build a "libtool" script and use
43    this to compile and link shared libraries, which are placed in a subdirectory
44    called .libs. The programs pcretest and pgrep are built to use these
45    uninstalled libraries by means of wrapper scripts. When you use "make install"
46    to install shared libraries, pgrep is automatically re-built to use the newly
47    installed library before it itself is installed.
48    
   ChangeLog         log of changes to the code  
   LICENCE           conditions for the use of PCRE  
   Makefile          for building PCRE  
   README            this file  
   RunTest           a shell script for running tests  
   Tech.Notes        notes on the encoding  
   pcre.3            man page for the functions  
   pcreposix.3       man page for the POSIX wrapper API  
   dftables.c        auxiliary program for building chartables.c  
   get.c             )  
   maketables.c      )  
   study.c           ) source of  
   pcre.c            )   the functions  
   pcreposix.c       )  
   pcre.h            header for the external API  
   pcreposix.h       header for the external POSIX wrapper API  
   internal.h        header for internal use  
   pcretest.c        test program  
   pgrep.1           man page for pgrep  
   pgrep.c           source of a grep utility that uses PCRE  
   perltest          Perl test program  
   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).  
49    
50  To run pcretest on just one of the test files, give its number as an argument  Building on non-Unix systems
51  to RunTest, for example:  ----------------------------
52    
53    For a non-Unix system, read the comments in the file NON-UNIX-USE. PCRE has
54    been compiled on Windows systems and on Macintoshes, but I don't know the
55    details because I don't use those systems. It should be straightforward to
56    build PCRE on any system that has a Standard C compiler, because it uses only
57    Standard C functions.
58    
59    
60    Testing PCRE
61    ------------
62    
63    To test PCRE on a Unix system, run the RunTest script in the pcre directory.
64    (This can also be run by "make runtest" or "make check".) For other systems,
65    see the instruction in NON-UNIX-USE.
66    
67    The script runs the pcretest test program (which is documented in
68    doc/pcretest.txt) on each of the testinput files (in the testdata directory) in
69    turn, and compares the output with the contents of the corresponding testoutput
70    file. A file called testtry is used to hold the output from pcretest. To run
71    pcretest on just one of the test files, give its number as an argument to
72    RunTest, for example:
73    
74    RunTest 3    RunTest 3
75    
76  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
77  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
78  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
79  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 is
80  widespread, these two test files may get amalgamated.  widespread, these two test files may get amalgamated.
# Line 103  output to say why. If running this test Line 96  output to say why. If running this test
96  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,
97  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.
98    
 To install PCRE, copy libpcre.a to any suitable library directory (e.g.  
 /usr/local/lib), pcre.h to any suitable include directory (e.g.  
 /usr/local/include), and pcre.3 to any suitable man directory (e.g.  
 /usr/local/man/man3).  
   
 To install the pgrep command, copy it to any suitable binary directory, (e.g.  
 /usr/local/bin) and pgrep.1 to any suitable man directory (e.g.  
 /usr/local/man/man1).  
   
99  PCRE has its own native API, but a set of "wrapper" functions that are based on  PCRE has its own native API, but a set of "wrapper" functions that are based on
100  the POSIX API are also supplied in the library libpcreposix.a. Note that this  the POSIX API are also supplied in the library libpcreposix.a. Note that this
101  just provides a POSIX calling interface to PCRE: the regular expressions  just provides a POSIX calling interface to PCRE: the regular expressions
# Line 161  You should not alter the set of characte Line 145  You should not alter the set of characte
145  will cause PCRE to malfunction.  will cause PCRE to malfunction.
146    
147    
148  The pcretest program  Manifest
149  --------------------  --------
150    
151    The distribution should contain the following files:
152    
153    (A) The actual source files of the PCRE library functions and their
154        headers:
155    
156      dftables.c            auxiliary program for building chartables.c
157      get.c                 )
158      maketables.c          )
159      study.c               ) source of
160      pcre.c                )   the functions
161      pcreposix.c           )
162      pcre.h                header for the external API
163      pcreposix.h           header for the external POSIX wrapper API
164      internal.h            header for internal use
165      config.in             template for config.h, which is built by configure
166    
167    (B) Auxiliary files:
168    
169      AUTHORS               information about the author of PCRE
170      ChangeLog             log of changes to the code
171      INSTALL               generic installation instructions
172      LICENCE               conditions for the use of PCRE
173      Makefile.in           template for Unix Makefile, which is built by configure
174      NEWS                  important changes in this release
175      NON-UNIX-USE          notes on building PCRE on non-Unix systems
176      README                this file
177      RunTest               a Unix shell script for running tests
178      config.guess          ) files used by libtool,
179      config.sub            )   used only when building a shared library
180      configure             a configuring shell script (built by autoconf)
181      configure.in          the autoconf input used to build configure
182      doc/Tech.Notes        notes on the encoding
183      doc/pcre.3            man page source for the PCRE functions
184      doc/pcre.html         HTML version
185      doc/pcre.txt          plain text version
186      doc/pcreposix.3       man page source for the POSIX wrapper API
187      doc/pcreposix.html    HTML version
188      doc/pcreposix.txt     plain text version
189      doc/pcretest.txt      documentation of test program
190      doc/perltest.txt      documentation of Perl test program
191      doc/pgrep.1           man page source for the pgrep utility
192      doc/pgrep.html        HTML version
193      doc/pgrep.txt         plain text version
194      install-sh            a shell script for installing files
195      ltconfig              ) files used to build "libtool",
196      ltmain.sh             )   used only when building a shared library
197      pcretest.c            test program
198      perltest              Perl test program
199      pgrep.c               source of a grep utility that uses PCRE
200      testdata/testinput1   test data, compatible with Perl 5.004 and 5.005
201      testdata/testinput2   test data for error messages and non-Perl things
202      testdata/testinput3   test data, compatible with Perl 5.005
203      testdata/testinput4   test data for locale-specific tests
204      testdata/testoutput1  test results corresponding to testinput1
205      testdata/testoutput2  test results corresponding to testinput2
206      testdata/testoutput3  test results corresponding to testinput3
207      testdata/testoutput4  test results corresponding to testinput4
208    
209  This program is intended for testing PCRE, but it can also be used for  (C) Auxiliary files for Win32 DLL
 experimenting with regular expressions.  
210    
211  If it is given two filename arguments, it reads from the first and writes to    dll.mk
212  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 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:  
   
   /caseless/i  
   
 These modifier letters have the same effect as they do in Perl. There are  
 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.  
213    
214  Philip Hazel <ph10@cam.ac.uk>  Philip Hazel <ph10@cam.ac.uk>
215  June 1999  January 2000

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