/usr/share/perl5/Tree/Simple/Visitor/PostOrderTraversal.pm is in libtree-simple-visitorfactory-perl 0.15-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 | package Tree::Simple::Visitor::PostOrderTraversal;
use strict;
use warnings;
our $VERSION = '0.15';
use Scalar::Util qw(blessed);
use base qw(Tree::Simple::Visitor);
sub new {
my ($_class) = @_;
my $class = ref($_class) || $_class;
my $visitor = {};
bless($visitor, $class);
$visitor->_init();
return $visitor;
}
sub visit {
my ($self, $tree) = @_;
(blessed($tree) && $tree->isa("Tree::Simple"))
|| die "Insufficient Arguments : You must supply a valid Tree::Simple object";
# get our filter function
my $filter_function = $self->getNodeFilter();
# use an inner subroutine to accomplish
# this traversal using recursion
my $_postOrderTraversal = sub {
my ($current_tree, $traversal_function) = @_;
# get a temporary results container
my @results;
# process each child
foreach my $child ($current_tree->getAllChildren()) {
# recurse our inner subroutine by passing itself
# to itself, and then collect the results of this
# recursion
push @results => $traversal_function->($child, $traversal_function);
}
# if we are root and we are not including the trunk then
# we can return our results now
return @results if $current_tree->isRoot() && !$self->includeTrunk();
# however, if we don't meet those conditions, then we
# need to process the current tree and add it to our
# results
push @results => (($filter_function) ?
$filter_function->($current_tree)
:
$current_tree->getNodeValue());
# and then return the results
return @results;
};
# now store the results in our object
$self->setResults($_postOrderTraversal->($tree, $_postOrderTraversal));
}
1;
__END__
=head1 NAME
Tree::Simple::Visitor::PostOrderTraversal - A Visitor for post-order traversal a Tree::Simple hierarchy
=head1 SYNOPSIS
use Tree::Simple::Visitor::PostOrderTraversal;
# create an visitor
my $visitor = Tree::Simple::Visitor::PostOrderTraversal->new();
# pass our visitor to the tree
$tree->accept($visitor);
# print our results
print join ", " => $visitor->getResults();
# this will print this:
# 1.1.1 1.1 1.2 1 2.1 2 3.1 3
# assuming your tree is like this:
# 1
# 1.1
# 1.1.1
# 1.2
# 2
# 2.1
# 3
# 3.1
=head1 DESCRIPTION
Post-order traversal is a variation of the depth-first traversal in which the sub-tree's are processed I<before> the parent. It is another alternative to Tree::Simple's C<traverse> method which implements a depth-first, pre-order traversal.
=head1 METHODS
=over 4
=item B<new>
There are no arguments to the constructor the object will be in its default state. You can use the C<setNodeFilter> method to customize its behavior.
=item B<includeTrunk ($boolean)>
Based upon the value of C<$boolean>, this will tell the visitor to include the trunk of the tree in the traversal as well.
=item B<setNodeFilter ($filter_function)>
This method accepts a CODE reference as its C<$filter_function> argument and throws an exception if it is not a code reference. This code reference is used to filter the tree nodes as they are collected. This can be used to customize output, or to gather specific information from a more complex tree node. The filter function should accept a single argument, which is the current Tree::Simple object.
=item B<visit ($tree)>
This is the method that is used by Tree::Simple's C<accept> method. It can also be used on its own, it requires the C<$tree> argument to be a Tree::Simple object (or derived from a Tree::Simple object), and will throw and exception otherwise.
=item B<getResults>
This method returns the accumulated results of the application of the node filter to the tree.
=back
=head1 BUGS
None that I am aware of. Of course, if you find a bug, let me know, and I will be sure to fix it.
=head1 CODE COVERAGE
See the B<CODE COVERAGE> section in L<Tree::Simple::VisitorFactory> for more information.
=head1 SEE ALSO
These Visitor classes are all subclasses of B<Tree::Simple::Visitor>, which can be found in the B<Tree::Simple> module, you should refer to that module for more information.
=head1 AUTHOR
stevan little, E<lt>stevan@iinteractive.comE<gt>
=head1 COPYRIGHT AND LICENSE
Copyright 2004, 2005 by Infinity Interactive, Inc.
L<http://www.iinteractive.com>
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
=cut
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