1package Heap::Elem::RefRev; 2 3use strict; 4use vars qw($VERSION @ISA @EXPORT @EXPORT_OK); 5use Heap::Elem; 6 7require Exporter; 8 9@ISA = qw(Exporter Heap::Elem); 10 11# No names exported. 12@EXPORT = ( ); 13 14# Available for export: RefRElem (to allocate a new Heap::Elem::RefRev value) 15@EXPORT_OK = qw( RefRElem ); 16 17$VERSION = '0.80'; 18 19sub RefRElem { # exportable synonym for new 20 Heap::Elem::RefRev->new(@_); 21} 22 23# compare two RefRev elems - the objects must have a compatible cmp method 24sub cmp { 25 return $_[1][0]->cmp( $_[0][0] ); 26} 27 281; 29__END__ 30 31=head1 NAME 32 33Heap::Elem::RefRev - Reversed Object Reverence Heap Elements 34 35=head1 SYNOPSIS 36 37 use Heap::Elem::RefRev( RefRElem ); 38 use Heap::Fibonacci; 39 40 my $heap = Heap::Fibonacci->new; 41 my $elem; 42 43 foreach $i ( 1..100 ) { 44 $obj = myObject->new( $i ); 45 $elem = RefRElem( $obj ); 46 $heap->add( $elem ); 47 } 48 49 while( defined( $elem = $heap->extract_top ) ) { 50 # assume that myObject object have a method I<printable> 51 print "Largest is ", $elem->val->printable, "\n"; 52 } 53 54=head1 DESCRIPTION 55 56Heap::Elem::RefRev is used to wrap object reference values into an 57element that can be managed on a heap. Each referenced object must 58have a method I<cmp> which can compare itself with any of the other 59objects that have references on the same heap. These comparisons 60must be consistant with normal arithmetic. The top of the heap will 61have the largest (according to I<cmp>) element still remaining. 62(See L<Heap::Elem::Ref> if you want the heap to always return the 63smallest element.) 64 65The details of the Elem interface are described in L<Heap::Elem>. 66 67The details of using a Heap interface are described in L<Heap>. 68 69=head1 AUTHOR 70 71John Macdonald, john@perlwolf.com 72 73=head1 COPYRIGHT 74 75Copyright 1998-2007, O'Reilly & Associates. 76 77This code is distributed under the same copyright terms as perl itself. 78 79=head1 SEE ALSO 80 81Heap(3), Heap::Elem(3), Heap::Elem::Ref(3). 82 83=cut 84