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

Monks, I've got a very long list of data that I need to parse but I'm unable to get my regex to stop being greedy. The data is formatted as follows... [[{bunches of data}, {more data}, {etc}], [{hey more data}, {etc}, {etc}], [{etc}, {etc}, {etc}]] and my regex looks like this, 
#counter is equal to the number of [] pairs
while($counter)
{

    if($content =~ /\[{(.*)?}\](.+)/)
        {
                   print OUT "$counter\n";
        print OUT "$1\n";

                $content = $2;
        }

    #}]], "plt":
    --$counter;
}

[download]
The idea is to get the regex to grab each [] pair one at a time but instead the first pass grabs everything up to the ending }]] Help me perl monks, you are my only hope

Replies are listed 'Best First'.
Re: Non Greedy?
by zwon (Abbot) on Jun 02, 2009 at 21:48 UTC
    $content =~ /\[{(.*?)}\](.+)/

    Update: also you can rewrite your loop as follows: 

    while ( $content =~ /\[{(.*?)}\]/g ) {
    print "$1\n";
}

    [download]
    note, that this doesn't use counter and just prints all occurrences.
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      gracias, I feel like a dummy
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Re: Non Greedy?
by ikegami (Patriarch) on Jun 02, 2009 at 21:53 UTC

    Your "?" is modifying "()" instead of "*". You want 

    / \[{ ( .*? ) }\] /x

    [download]
    or 
    / \[{ ( [^\]]* ) }\] /x

    [download]

    Note that your strategy only works if all the content is two-level deep.

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Re: Non Greedy?
by carlin (Beadle) on Jun 02, 2009 at 21:51 UTC
    Should

    /\[{(.*)?}\](.+)/

    not be

    /\[{(.*?)}\](.+)/

    With the question mark inside the brackets?
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Re: Non Greedy?
by citromatik (Curate) on Jun 02, 2009 at 23:54 UTC

    Some gave you hints to solve your regexp problem. I will give you a quick-n-dirty non-regexp related solution (I will never put a code like this in production):

    use strict;
use warnings;
use Data::Dumper;

my $i = "[[{bunches_of_data}, {more_data}, {etc}], [{hey_more_data}, {
+etc}, {etc}], [{etc}, {etc}, {etc}]]";

$i =~ s/{|}//g;
$i =~ s/([^\[\],\s]+)/'$1'/g;

my $iv = eval "$i";
print Dumper $iv;

    [download]

    Outputs:

    $VAR1 = [
          [
            'bunches_of_data',
            'more_data',
            'etc'
          ],
          [
            'hey_more_data',
            'etc',
            'etc'
          ],
          [
            'etc',
            'etc',
            'etc'
          ]
        ];

    [download]

    citromatik

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Re: Non Greedy?
by Devasundaram (Initiate) on Jun 03, 2009 at 07:50 UTC
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