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NUFFIN / Algorithm-Dependency-Objects-0.04 / lib / Algorithm / Dependency / Objects / Ordered.pm 

            

              
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#!/usr/bin/perl
package Algorithm::Dependency::Objects::Ordered;
use base qw/Algorithm::Dependency::Objects/;
use strict;
use warnings;
use Scalar::Util qw/refaddr/;
use Carp qw/croak/;
sub schedule {
        my ( $self, @args ) = @_;
        $self->_order($self->SUPER::schedule(@args));
}
sub schedule_all {
        my ( $self, @args ) = @_;
        $self->_order($self->SUPER::schedule_all(@args));
}
sub _order {
        my ( $self, @queue ) = @_;
        my $selected = Set::Object->new( $self->selected->members );
        my $error_marker;
        my @schedule;
        my %dep_set; 
        while (@queue){
                my $obj = shift @queue;
                if ( defined($error_marker) and refaddr($error_marker) == refaddr($obj) ) {
                        $self->circular_dep($obj, @queue);
                }
                 
                my $dep_set = $dep_set{refaddr $obj} ||= Set::Object->new( $self->get_deps($obj) );
                unless ( $selected->superset($dep_set) ) {
                        # we have some missing deps
                        # put the object back in the queue
                        push @queue, $obj;
                        # if we encounter it again without any change
                        # then a circular dependency is detected
                        $error_marker = $obj unless defined $error_marker;
                } else {
                        # the dependancies are a subset of the selected objects,
                        # so they are all resolved.
                        push @schedule, $obj;
                        # mark the object as selected
                        $selected->insert($obj);
                        # since something changed we can forget about the error marker
                        undef $error_marker;
                }
        }
        # return the ordered list
        @schedule;
}
sub circular_dep {
        my ( $self, $obj, @queue ) = @_;
        croak "Circular dependency detected at $obj (queue: @queue)"
}
__PACKAGE__
__END__
=pod
=head1 NAME
Algorithm::Dependency::Objects::Ordered - An ordered dependency set
=head1 SYNOPSIS
        use Algorithm::Dependency::Objects::Ordered;
        my $o = Algorithm::Dependency::Ordered->new(
                objects => \@some_objects,
        );
        foreach my $object ( $o->schedule_all ) {
                print "$object, then...\n";             
        }
        print "done\n";
=head1 DESCRIPTION
=head1 METHODS
=over 4
=item B<new>
=item B<objects>
=item B<selected>
=item B<depends>
=item B<schedule>
=item B<schedule_all>
=item B<circular_dep>
=back
=head1 SEE ALSO
Adam Kennedy's excellent L<Algorithm::Dependency::Ordered> module, upon which this is based.
=head1 AUTHORS
Yuval Kogman
Stevan Little
COPYRIGHT AND LICENSE 
Copyright (C) 2005, 2007 Yuval Kogman, Stevan Little
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
=cut