1 2package Tree::Simple::Visitor::PreOrderTraversal; 3 4use strict; 5use warnings; 6 7our $VERSION = '0.01'; 8 9use base qw(Tree::Simple::Visitor); 10 11# make sure we use the "new" interface 12# so we enforce it here 13sub new { 14 my ($_class) = @_; 15 my $class = ref($_class) || $_class; 16 my $visitor = $class->SUPER::new(); 17 return $visitor; 18} 19 201; 21 22__END__ 23 24=head1 NAME 25 26Tree::Simple::Visitor::PreOrderTraversal - A Visitor for pre-order traversal a Tree::Simple hierarchy 27 28=head1 SYNOPSIS 29 30 use Tree::Simple::Visitor::PreOrderTraversal; 31 32 # create an visitor 33 my $visitor = Tree::Simple::Visitor::PreOrderTraversal->new(); 34 35 # pass our visitor to the tree 36 $tree->accept($visitor); 37 38 # print our results 39 print join ", " => $visitor->getResults(); 40 41 # this will print this: 42 # 1 1.1 1.1.1 1.2 2 2.1 3 3.1 43 # assuming your tree is like this: 44 # 1 45 # 1.1 46 # 1.1.1 47 # 1.2 48 # 2 49 # 2.1 50 # 3 51 # 3.1 52 53=head1 DESCRIPTION 54 55Pre-order traversal is a depth-first traversal method in which the sub-tree's are processed I<after> the parent. It is essentially a wrapper around the base Tree::Simple::Visitor class, and is a seperate module here for completeness. (If you have a post-order, you should have a pre-order too). 56 57=head1 METHODS 58 59=over 4 60 61=item B<new> 62 63There are no arguments to the constructor the object will be in its default state. You can use the C<setNodeFilter> method to customize its behavior. 64 65=item B<includeTrunk ($boolean)> 66 67Based upon the value of C<$boolean>, this will tell the visitor to include the trunk of the tree in the traversal as well. 68 69=item B<setNodeFilter ($filter_function)> 70 71This method accepts a CODE reference as its C<$filter_function> argument and throws an exception if it is not a code reference. This code reference is used to filter the tree nodes as they are collected. This can be used to customize output, or to gather specific information from a more complex tree node. The filter function should accept a single argument, which is the current Tree::Simple object. 72 73=item B<visit ($tree)> 74 75This 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. 76 77=item B<getResults> 78 79This method returns the accumulated results of the application of the node filter to the tree. 80 81=back 82 83=head1 BUGS 84 85None that I am aware of. Of course, if you find a bug, let me know, and I will be sure to fix it. 86 87=head1 CODE COVERAGE 88 89See the B<CODE COVERAGE> section in L<Tree::Simple::VisitorFactory> for more inforamtion. 90 91=head1 SEE ALSO 92 93These 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. 94 95=head1 AUTHOR 96 97stevan little, E<lt>stevan@iinteractive.comE<gt> 98 99=head1 COPYRIGHT AND LICENSE 100 101Copyright 2004, 2005 by Infinity Interactive, Inc. 102 103L<http://www.iinteractive.com> 104 105This library is free software; you can redistribute it and/or modify 106it under the same terms as Perl itself. 107 108=cut 109 110