use strict;
use warnings;

sub hashIteratorFactory {
    my $h = shift;
    my @both;
    my $exhausted = 0;
    return sub {
        my $i = 0;
        return sub {
            my ($k, $v);
            if( !defined $both[$i] ) {
                if( !$exhausted and (( $k, $v ) = each %$h) ) {
                    push @both, [ $k, $v ];
                } else {
                    $exhausted = 1;
                    $i = 0;
                    return wantarray() ? () : undef();
                }
            } else {
                ( $k, $v ) = @{$both[$i]};
            }
            $i++;
            return wantarray() ? ( $k, $v ) : $k;
        }
    }
}

my %h;
@h{'a'..'d'} = 1..4;

my $factory = hashIteratorFactory( \%h );
my $i1 = $factory->();
my $i2 = $factory->();

print "1:",$i1->(),"\n";
print "1:",$i1->(),"\n";
print "2:",$i2->(),"\n";
print "1:",$i1->(),"\n";
print "1:",$i1->(),"\n";
print "2:",$i2->(),"\n";
print "2:",$i2->(),"\n";
print "1:",$i1->(),"\n";
print "1:",$i1->(),"\n";
print "2:",$i2->(),"\n";
print "2:",$i2->(),"\n";

my $i3 = $factory->();
while( my ($k, $v) = $i3->() ) {
    print "3:$k$v\n";
}

print "2:",$i2->(),"\n";
print "1:",$i1->(),"\n";