Tree::Simple::Visitor::PreOrderTraversal - A Visitor for pre-order traversal a Tree::Simple hierarchy


  use Tree::Simple::Visitor::PreOrderTraversal;

  # create an visitor
  my $visitor = Tree::Simple::Visitor::PreOrderTraversal->new();

  # pass our visitor to the tree

  # print our results
  print join ", " => $visitor->getResults();

  # this will print this:
  #   1 1.1 1.1.1 1.2 2 2.1 3 3.1
  # assuming your tree is like this:
  #   1
  #     1.1
  #       1.1.1
  #     1.2
  #   2
  #     2.1
  #   3
  #     3.1


Pre-order traversal is a depth-first traversal method in which the sub-tree's are processed after the parent. It is essentially a wrapper around the base Tree::Simple::Visitor class, and is a separate module here for completeness. (If you have a post-order, you should have a pre-order too).



There are no arguments to the constructor the object will be in its default state. You can use the setNodeFilter method to customize its behavior.

includeTrunk ($boolean)

Based upon the value of $boolean, this will tell the visitor to include the trunk of the tree in the traversal as well.

setNodeFilter ($filter_function)

This method accepts a CODE reference as its $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.

visit ($tree)

This is the method that is used by Tree::Simple's accept method. It can also be used on its own, it requires the $tree argument to be a Tree::Simple object (or derived from a Tree::Simple object), and will throw and exception otherwise.


This method returns the accumulated results of the application of the node filter to the tree.


None that I am aware of. Of course, if you find a bug, let me know, and I will be sure to fix it.


See the CODE COVERAGE section in Tree::Simple::VisitorFactory for more information.


These Visitor classes are all subclasses of Tree::Simple::Visitor, which can be found in the Tree::Simple module, you should refer to that module for more information.


stevan little, <>


Copyright 2004, 2005 by Infinity Interactive, Inc.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.