Regexp::Common balanced brackets non-capture multiple occurances

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

#!/usr/bin/perl
use strict;
use diagnostics;

use Data::Dumper;
use Regexp::Common qw(balanced);

my $re=$RE{balanced}{-parens=>'[]'};

# a valid string is: beginning, one or more [things] perhaps seperated
+ by whitespace, end
foreach (
    'a [foo]  [bar][quux] grmbl42', #1  ok
    'a [foo]  [bar]bla[quux] grmbl42', #2 nok: has random crap instead
+ of whitespace
    'a [foo]  [bar] grmbl42',    #3 ok
    'a [foo] grmbl42',  #4 ok
    'a [fo grmbl42',    #5 nok: unbalanced
    'a [fo]o] grmbl42',    #6 nok: unbalanced
    'a [fo[o] grmbl42',    #7 nok: unbalanced
    'a o] grmbl42',    #8 nok: unbalanced
    'a grmbl42', #9 nok: no [] at all
) {
    my $didit=/^
        a         # literal a
        \s*       # optional whitespace
        (?:
            $re
            \s*
        )+
        .*        # something
        42        # literal 42
    $/x;
    print Dumper $_, $didit;
};
[download]

Should fail #2 and #6, but doesn't. Why?

Comment on Regexp::Common balanced brackets non-capture multiple occurances Download Code

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Re: Regexp::Common balanced brackets non-capture multiple occurances by davidrw (Prior) on Jul 03, 2006 at 15:20 UTC
If you add capturing you can see what it's doing .. `my $didit=/^ a # literal a \s* # optional whitespace ((?: $re \s* )+) (.) # something 42 # literal 42 $/x; print Dumper [$_, $didit?($1,$2):(undef,undef), $didit];` [download] For exampl, with #2 & #6 that gives: `# 2 $VAR1 = [ 'a [foo] [bar]bla[quux] grmbl42', '[foo] [bar]', 'bla[quux] grmbl', '1' ]; # 6 $VAR1 = [ 'a [fo]o] grmbl42', '[fo]', 'o] grmbl', '1' ];` [download] The issue is with the "something" `.` -- it just sucks up anything bad.	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re: Regexp::Common balanced brackets non-capture multiple occurances
by davidrw (Prior) on Jul 03, 2006 at 15:20 UTC

    my $didit=/^
        a         # literal a
        \s*       # optional whitespace
        ((?:
            $re
            \s*
        )+)
        (.*)        # something
        42        # literal 42
    $/x;
    print Dumper [$_, $didit?($1,$2):(undef,undef),  $didit];
[download]

# 2
$VAR1 = [
          'a [foo]  [bar]bla[quux] grmbl42',
          '[foo]  [bar]',
          'bla[quux] grmbl',
          '1'
        ];
# 6
$VAR1 = [
          'a [fo]o] grmbl42',
          '[fo]',
          'o] grmbl',
          '1'
        ];
[download]

.*

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