# $Id: Traversal.pm,v 1.7 2004/11/10 09:40:06 radams Exp $
#
# BioPerl module for Bio::Graph::SimpleGraph::Traversal;
#
# You may distribute this module under the same terms as perl itself
# POD documentation - main docs before the code

=head1 NAME

Bio::Graph::SimpleGraph::Traversal;

=head1 SYNOPSIS

=head1 DESCRIPTION

=head1 FEEDBACK

=head2 Mailing Lists

User feedback is an integral part of the evolution of this and other
Bioperl modules. Send your comments and suggestions preferably to one
of the Bioperl mailing lists. Your participation is much appreciated.

  bioperl-l@bioperl.org              - General discussion
  http://bio.perl.org/MailList.html  - About the mailing lists

=head2 Reporting Bugs

Report bugs to the Bioperl bug tracking system to help us keep track
the bugs and their resolution.  Bug reports can be submitted via email
or the web:

  bioperl-bugs@bioperl.org
  http://bugzilla.bioperl.org/

=head1 AUTHOR - Richard Adams

Email richard.adams@ed.ac.uk

=cut

package Bio::Graph::SimpleGraph::Traversal;
use vars qw(@ISA @AUTO_ATTRIBUTES @OTHER_ATTRIBUTES %SYNONYMS %DEFAULTS);
use Class::AutoClass;
use Bio::Graph::SimpleGraph;
use strict;
@ISA = qw(Class::AutoClass); # AutoClass must be first!!

@AUTO_ATTRIBUTES=qw(order what graph start is_initialized
		    _past _present _future);
@OTHER_ATTRIBUTES=qw();
%SYNONYMS=();
%DEFAULTS=(order   => 'dfs',
	        what   => 'node',
	       _past   => {},
	      _future  => []);
Class::AutoClass::declare(__PACKAGE__);

sub _init_self {
	my($self,$class,$args)=@_;
	return unless $class eq __PACKAGE__; 
	# to prevent subclasses from re-running this
	$self->graph or $self->graph(new Bio::Graph::SimpleGraph);
	# can't be in DEFAULTS - circular includes!
}

sub has_next {
  my($self)=@_;
  $self->reset unless $self->is_initialized;
  @{$self->_future}>0;
}

sub get_next {
  my($self)= @_;
  $self->reset unless $self->is_initialized;
  my $past   = $self->_past;
  my $future = $self->_future;
  my $present;
  my $graph  = $self->graph;
  while (@$future) {
    $present = shift @$future;
    unless($past->{$present}) {	# this is a new node
      $self->_present($present);
      $past->{$present}=1;
      if ($self->order =~ /^d/i) {
		unshift(@$future,$graph->neighbors($present,$self->what));
      } else {
		push(@$future,$graph->neighbors($present,$self->what));
      }
       return $present;
    }
  }
  $self->_present(undef);
}

sub get_all {
  my($self, $val)   = @_;
  $self->reset unless $self->is_initialized;
  my $past    = $self->_past;
  my $future  = $self->_future;
  my $i = 0; 
  my $present;
  my $graph   = $self->graph;
  my $nodes   = $graph->_nodes;

  my $results =[];
  while (@$future) {
    $present = shift @$future;
     if(!$past->{$present}) {	# this is a new node
         $past->{$present} = 1;

         push(@$results,$present);
		 $i++;
         if ($self->order =~ /^d/i) {
		    unshift(@$future,$graph->neighbors($present,$self->what));
             } else {
			push(@$future,$graph->neighbors($present,$self->what));
           }
        }
  }
  $self->_present(undef);
  wantarray? @$results: $results;
}

sub get_this {
  my($self)=@_;
  $self->reset unless $self->is_initialized;
  $self->_present;
}

sub reset {
  my($self)= @_;
  $self->_past({});
  $self->order('d');
  $self->_present(undef);
  $self->_future([]);
  $self->is_initialized(1);
  my $graph = $self->graph;
  my $start = $self->start;
  my $what  = $self->what || 'node';
  if ($what=~/^n/i) {
    defined $start or $start=$graph->nodes->[0];
  } elsif ($what=~/^e/i) {
    $start=defined $start? $graph->edge($start): $graph->edges->[0];
  } else {
    $self->throw("Unrecognized \$what parameter $what: should be 'node' or 'edge'");
  }
  return unless defined $start;
  $self->_future([$start]);
}

1;
