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Regexp::Common::balanced -- provide regexes for strings with balanced parenthesized delimiters or arbitrary delimiters.


    use Regexp::Common qw /balanced/;

    while (<>) {
                                   and print q{balanced parentheses\n};


Please consult the manual of Regexp::Common for a general description of the works of this interface.

Do not use this module directly, but load it via Regexp::Common.


Returns a pattern that matches a string that starts with the nominated opening parenthesis or bracket, contains characters and properly nested parenthesized subsequences, and ends in the matching parenthesis.

More than one type of parenthesis can be specified:


in which case all specified parenthesis types must be correctly balanced within the string.

If we are using C{-keep} (See Regexp::Common):


captures the entire expression

$RE{balanced}{-begin => "begin"}{-end => "end"}

Returns a pattern that matches a string that is properly balanced using the begin and end strings as start and end delimiters. Multiple sets of begin and end strings can be given by separating them by |s (which can be escaped with a backslash).

    qr/$RE{balanced}{-begin => "do|if|case"}{-end => "done|fi|esac"}/

will match properly balanced strings that either start with do and end with done, start with if and end with fi, or start with case and end with esac.

If -end contains less cases than -begin, the last case of -end is repeated. If it contains more cases than -begin, the extra cases are ignored. If either of -begin or -end isn't given, or is empty, -begin => '(' and -end => ')' are assumed.

If we are using C{-keep} (See Regexp::Common):


captures the entire expression


 $Log: balanced.pm,v $
 Revision 2.101  2003/02/01 22:55:31  abigail
 Changed Copyright years

 Revision 2.100  2003/01/21 23:19:40  abigail
 The whole world understands RCS/CVS version numbers, that 1.9 is an
 older version than 1.10. Except CPAN. Curse the idiot(s) who think
 that version numbers are floats (in which universe do floats have
 more than one decimal dot?).
 Everything is bumped to version 2.100 because CPAN couldn't deal
 with the fact one file had version 1.10.

 Revision 1.6  2002/08/20 15:20:48  abigail
 Documented -begin and -end

 Revision 1.5  2002/08/08 23:57:33  abigail
 Added HISTORY section.

 Revision 1.4  2002/08/08 23:53:54  abigail
 Reworked and extended $RE{balanced}. It now takes multiple arbitrary
 length delimiters. -parens is just a short-cut for some of the common,
 simpler cases.

 Revision 1.3  2002/08/05 12:16:58  abigail
 Fixed 'Regex::' and 'Rexexp::' typos to 'Regexp::'
 (Found my Mike Castle).

 Revision 1.2  2002/07/25 22:37:44  abigail
 Added 'use strict'.
 Added 'no_defaults' to 'use Regexp::Common' to prevent loaded of all

 Revision 1.1  2002/07/25 22:14:44  abigail
 Factored out from Regexp::Common.


Regexp::Common for a general description of how to use this interface.


Damian Conway (damian@conway.org)


This package is maintained by Abigail (regexp-common@abigail.nl).


Bound to be plenty.

For a start, there are many common regexes missing. Send them in to regexp-common@abigail.nl.


     Copyright (c) 2001 - 2003, Damian Conway. All Rights Reserved.
       This module is free software. It may be used, redistributed
      and/or modified under the terms of the Perl Artistic License
            (see http://www.perl.com/perl/misc/Artistic.html)