NAME

       Tree::Binary - An implementation of a binary tree

SYNOPSIS

         my $tree = Tree::Binary->new( 'root' );

         my $left = Tree::Binary->new( 'left' );
         $tree->left( $left );

         my $right = Tree::Binary->new( 'left' );
         $tree->right( $right );

         my $right_child = $tree->right;

         $tree->right( undef ); # Unset the right child.

         my @nodes = $tree->traverse( $tree->POST_ORDER );

         my $traversal = $tree->traverse( $tree->IN_ORDER );
         while ( my $node = $traversal->() ) {
             # Do something with $node here
         }

DESCRIPTION

       This is an implementation of a binary tree. This class inherits from Tree, which is an
       N-ary tree implemenation. Because of this, this class actually provides an implementation
       of a complete binary tree vs. a sparse binary tree.  The empty nodes are instances of
       Tree::Null, which is described in Tree.  This should have no effect on your usage of this
       class.

METHODS

       In addition to the methods provided by Tree, the following items are provided or
       overriden.

       •   "left([$child])" / "right([$child])"

           These access the left and right children, respectively. They are mutators, which means
           that their behavior changes depending on if you pass in a value.

           If you do not pass in any parameters, then it will act as a getter for the specific
           child, return the child (if set) or undef (if not).

           If you pass in a child, it will act as a setter for the specific child, setting the
           child to the passed-in value and returning the $tree. (Thus, this method chains.)

           If you wish to unset the child, do "$tree>left( undef );"

       •   "children()"

           This will return the children of the tree.

           NOTE: There will be two children, always. Tree::Binary implements a complete binary
           tree, filling in missing children with Tree::Null objects.  (Please see Tree::Fast for
           more information on Tree::Null.)

       •   traverse( [$order] )

           When called in list context ("my @traversal = $tree->traverse()"), this will return a
           list of the nodes in the given traversal order. When called in scalar context ("my
           $traversal = $tree->traverse()"), this will return a closure that will, over
           successive calls, iterate over the nodes in the given traversal order. When finished
           it will return false.

           The default traversal order is pre-order.

           In addition to the traversal orders provided by Tree, Tree::Binary provides in-order
           traversals.

           •   In-order

               This will return the result of an in-order traversal on the left node (if any),
               then the node, then the result of an in-order traversal on the right node (if
               any).

       NOTE: You have access to all the methods provided by Tree, but it is not recommended that
       you use many of them, unless you know what you're doing. This list includes "add_child()"
       and "remove_child()".

TODO

       •   Make in-order closure traversal work iteratively

       •   Make post-order closure traversal work iteratively

CODE COVERAGE

       Please see the relevant sections of Tree.

SUPPORT

       Please see the relevant sections of Tree.

AUTHORS

       Rob Kinyon <rob.kinyon@iinteractive.com>

       Stevan Little <stevan.little@iinteractive.com>

       Thanks to Infinity Interactive for generously donating our time.

COPYRIGHT AND LICENSE

       Copyright 2004, 2005 by Infinity Interactive, Inc.

       <http://www.iinteractive.com>

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