#!/user/bin/perl
use strict;
use warnings;
use feature 'say';
# use Benchmark qw(:all) ; # WindowsOS
use Benchmark::Forking qw( timethese cmpthese ); # UnixOS

my( %DetailSheet ) =    (
    'ColumnName' => {
    'ID' => {
        'PositionAdjustment' => 0,
        'RecordName' => 'Identification',
        'RecordNumber' => 0,
        'RecordValue' => '',
        'XlsName' => 'Reference',
        'XlsColumn' => 1,
        'XlsFormat' => '',
        'XlsWidth' => 15,
        'XlsLock' => 1,
        'GuiName' => 'Number',
        'GuiNumber' => 2,
        'GuiValue' => '',
        'Switch' => [
            ['O','0'],
            ['l','1']
        ]
    },
        'DESCRIPTION' => {
        'PositionAdjustment' => 0,
            'RecordName' => 'Description',
            'RecordNumber' => 1,
            'RecordValue' => '',
            'XlsName' => 'Description',
            'XlsColumn' => 2,
            'XlsFormat' => '',
            'XlsWidth' => 15,
            'XlsLock' => 1,
            'GuiName' => 'Description',
            'GuiNumber' => 3,
            'GuiValue' => '',
            'Switch' => [
            [' AND ', ' & '],
            [' WITH ', ' W/ ']
            ]
    }
    }
    );

sub getKeyByIteration {
    my ( $DetailSheet ) = @_;
    for my $key ( keys %$DetailSheet ) {
    for my $secondLevelKeys ( keys %{ $DetailSheet->{$key}} ) {
        while (my ($key, $value) = each %{ $DetailSheet->{$key}{$secon
+dLevelKeys} }) {
        return $secondLevelKeys if ($key eq 'XlsColumn' && $value == 2
+);
        }
    }
    }
}

# say getKeyByIteration(\%DetailSheet);

sub getKeyByGrep {
    my ( $DetailSheet ) = @_;
    return grep { $DetailSheet{ColumnName}{$_}{XlsColumn} == 2 }
    keys %{$DetailSheet{ColumnName}};
}

# say getKeyByGrep(\%DetailSheet);

my $results = timethese(100000000, { Grep => \&getKeyByGrep,
                     ForEach => \&getKeyByIteration, }, 'none');
cmpthese( $results );

__END__

$ perl test.pl
             Rate    Grep ForEach
Grep    1972776/s      --    -51%
ForEach 4011231/s    103%      --
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