package A2B::PartialPath;

use strict;

use vars qw(@ISA);

use Heap::Elem;

@ISA = qw(Heap::Elem);

sub new {
 	my ($package, $from) = @_;
	return bless {
		path => A2B::Path->new,
		nodes => {$from => 1},
		node => $from,
		heap_data => undef,
	}, $package;
}

sub goodness {
	my $self = shift;
	return $self->{path}->goodness;
}

sub node {
	my $self = shift;
	return $self->{node};
}

sub contains_node {
	my $self = shift;
	my $node = shift;
	return $self->{nodes}{$node};
}

sub path {
	my $self = shift;
	return $self->{path};
}

sub new_step {
	my ($self, $step) = @_;
	my $step_to = $step->to;
	return bless {
		path => $self->{path}->new_step($step),
		nodes => {%{$self->{nodes}}, $step_to => 1},
		node => $step_to,
	}, ref $self;
}

# comparitor for the priority queue - we want HIGH goodness values to be
# returned first
sub cmp {
	my ($a, $b) = @_;
	return $b->{path}->goodness <=> $a->{path}->goodness;
}

# get or set value slot
sub val {
	if (@_ > 1) { die "can't set value"; }
	return $_[0]->{path}->goodness;
}

# get or set heap slot
sub heap {
    @_ > 1 ? ($_[0]{heap_data} = $_[1]) : $_[0]{heap_data};
}

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