use warnings;
use strict;
use Benchmark qw/cmpthese/;
use Algorithm::Loops qw/NestedLoops/;
use Test::More 'no_plan';

my @outer = ( 'aa' .. 'jj' );
my @inner = ( 'AA' .. 'JJ' );


my $count = 100;

my $control = \&sliced;

foreach my $compare ( \&for_each, \&nested_loops, \&mapped ) {
    is_deeply( 
        $compare->( \@outer, \@inner ),
        $control->( \@outer, \@inner ),
        "Control matched."
    );
}



cmpthese( $count, {
    foreach     => sub{ my $res =     for_each( \@outer, \@inner )  },
    NestedLoops => sub{ my $res = nested_loops( \@outer, \@inner )  },
    mapped      => sub{ my $res =       mapped( \@outer, \@inner )  },
    sliced      => sub{ my $res =       sliced( \@outer, \@inner )  },
} );
    
    
sub for_each {
    my %hash;
    foreach my $out (  @{ $_[0] }  ) {
        foreach my $in (  @{ $_[1] }  ) {
            $hash{$out}{$in} = 1;
        }
    }
    return \%hash;
}


sub nested_loops {
    my %hash;
    NestedLoops(
        [  $_[0],  $_[1]  ],
        sub {  $hash{ $_[0] }{ $_[1] } = 1;  }
    );
    return \%hash;
}


sub mapped {
    my %hash = map{ $_ => 
        {  map {  $_ => 1  } @{ $_[1] }  }
    } @{ $_[0] };
    return \%hash;
}


sub sliced {
    my %hash;
    @{ $hash{$_} }{ @{ $_[1] } } 
        = (1) x @{ $_[1] } for @{ $_[0] };
    return \%hash;
}