File Coverage

blib/lib/Number/Natural/SetTheory.pm

Criterion	Covered	Total	%
statement	59	63	93.6
branch	20	30	66.6
condition	8	18	44.4
subroutine	11	11	100.0
pod	4	4	100.0
total	102	126	80.9

package Number::Natural::SetTheory;

use 5.010;
use boolean;
use JSON qw/to_json/;
use strict;
use utf8;

our (@EXPORT, @EXPORT_OK, %EXPORT_TAGS);

BEGIN
{
	$Number::Natural::SetTheory::AUTHORITY = 'cpan:TOBYINK';
	$Number::Natural::SetTheory::VERSION   = '0.004';

	@EXPORT    = qw/ /;
	@EXPORT_OK = qw/ set_is_number set_to_number number_to_set set_to_string /;
	$EXPORT_TAGS{'all'} = \@EXPORT_OK;
	$EXPORT_TAGS{'default'} = $EXPORT_TAGS{'standard'} = \@EXPORT;
}

use base qw/Exporter/;

sub set_is_number
{
	my ($set, $number) = @_;
	return undef unless int($number)==$number;

	if (!ref $set and $set =~ /^\d+$/ and int($set)==$set)
	{
		return ($set==$number) ? true : false;
	}

	return undef unless ref $set eq 'ARRAY';

	my $count = scalar @$set;

	return false
		if ($count != $number);

	return true
		if ($count == 0);

	my %accounted_for = map { $_ => false } 0..($count - 1);

	foreach my $member (@$set)
	{
		my $number = set_to_number($member);

		if (defined $number and exists $accounted_for{$number})
		{
			if ($accounted_for{$number})
			{
				return false;
			}
			elsif (not $accounted_for{$number})
			{
				$accounted_for{$number} = true;
			}
		}
	}

	if (grep { !$_ } values %accounted_for)
	{
		return false;
	}

	return true;
}

sub number_to_set
{
	my ($num) = @_;

	unless ($num =~ /^\d+$/ and int($num)==$num)
	{
		return undef;
	}

	return [] if $num==0;
	my @set = map { number_to_set($_) } 0 .. ($num-1);
	return \@set;
}

sub set_to_number
{
	my ($set) = @_;

	if (!ref $set and $set =~ /^\d+$/ and int($set)==$set)
	{
		return $set;
	}

	return undef unless ref $set eq 'ARRAY';

	if (set_is_number($set, scalar @$set))
	{
		return scalar @$set;
	}

	return undef;
}

sub set_to_string
{
	my ($set) = @_;
	my $string = to_json($set);
	$string =~ s/\[/\{/g;
	$string =~ s/\]/\}/g;
	return $string;
}

'What exactly is zero?';

__END__