2 package Tree::Simple::Visitor::PostOrderTraversal;
9 use Scalar::Util qw(blessed);
11 use base qw(Tree::Simple::Visitor);
15 my $class = ref($_class) || $_class;
17 bless($visitor, $class);
23 my ($self, $tree) = @_;
24 (blessed($tree) && $tree->isa("Tree::Simple"))
25 || die "Insufficient Arguments : You must supply a valid Tree::Simple object";
26 # get our filter function
27 my $filter_function = $self->getNodeFilter();
28 # use an inner subroutine to accomplish
29 # this traversal using recursion
30 my $_postOrderTraversal = sub {
31 my ($current_tree, $traversal_function) = @_;
32 # get a temporary results container
35 foreach my $child ($current_tree->getAllChildren()) {
36 # recurse our inner subroutine by passing itself
37 # to itself, and then collect the results of this
39 push @results => $traversal_function->($child, $traversal_function);
41 # if we are root and we are not including the trunk then
42 # we can return our results now
43 return @results if $current_tree->isRoot() && !$self->includeTrunk();
44 # however, if we dont meet those conditions, then we
45 # need to process the current tree and add it to our
47 push @results => (($filter_function) ?
48 $filter_function->($current_tree)
50 $current_tree->getNodeValue());
51 # and then return the results
54 # now store the results in our object
55 $self->setResults($_postOrderTraversal->($tree, $_postOrderTraversal));
64 Tree::Simple::Visitor::PostOrderTraversal - A Visitor for post-order traversal a Tree::Simple hierarchy
68 use Tree::Simple::Visitor::PostOrderTraversal;
71 my $visitor = Tree::Simple::Visitor::PostOrderTraversal->new();
73 # pass our visitor to the tree
74 $tree->accept($visitor);
77 print join ", " => $visitor->getResults();
79 # this will print this:
80 # 1.1.1 1.1 1.2 1 2.1 2 3.1 3
81 # assuming your tree is like this:
93 Post-order traversal is a variation of the depth-first traversal in which the sub-tree's are processed I<before> the parent. It is another alternative to Tree::Simple's C<traverse> method which implements a depth-first, pre-order traversal.
101 There are no arguments to the constructor the object will be in its default state. You can use the C<setNodeFilter> method to customize its behavior.
103 =item B<includeTrunk ($boolean)>
105 Based upon the value of C<$boolean>, this will tell the visitor to include the trunk of the tree in the traversal as well.
107 =item B<setNodeFilter ($filter_function)>
109 This method accepts a CODE reference as its C<$filter_function> argument and throws an exception if it is not a code reference. This code reference is used to filter the tree nodes as they are collected. This can be used to customize output, or to gather specific information from a more complex tree node. The filter function should accept a single argument, which is the current Tree::Simple object.
111 =item B<visit ($tree)>
113 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.
117 This method returns the accumulated results of the application of the node filter to the tree.
123 None that I am aware of. Of course, if you find a bug, let me know, and I will be sure to fix it.
127 See the B<CODE COVERAGE> section in L<Tree::Simple::VisitorFactory> for more inforamtion.
131 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.
135 stevan little, E<lt>stevan@iinteractive.comE<gt>
137 =head1 COPYRIGHT AND LICENSE
139 Copyright 2004, 2005 by Infinity Interactive, Inc.
141 L<http://www.iinteractive.com>
143 This library is free software; you can redistribute it and/or modify
144 it under the same terms as Perl itself.