Redmine/vendor/gems/rubytree-0.5.2/lib/tree/binarytree.rb

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# binarytree.rb
#
# $Revision: 1.5 $ by $Author: anupamsg $
# $Name: $
#
# = binarytree.rb - Binary Tree implementation
#
# Provides a generic tree data structure with ability to
# store keyed node elements in the tree. The implementation
# mixes in the Enumerable module.
#
# Author:: Anupam Sengupta (anupamsg@gmail.com)
#
# Copyright (c) 2007 Anupam Sengupta
#
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification,
# are permitted provided that the following conditions are met:
#
# - Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# - Redistributions in binary form must reproduce the above copyright notice, this
# list of conditions and the following disclaimer in the documentation and/or
# other materials provided with the distribution.
#
# - Neither the name of the organization nor the names of its contributors may
# be used to endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
# ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
require 'tree'
module Tree
# Provides a Binary tree implementation. This tree node allows only two child
# nodes (left and right childs). It also provides direct access to the left
# and right children, including assignment to the same.
class BinaryTreeNode < TreeNode
# Adds the specified child node to the receiver node. The child node's
# parent is set to be the receiver. The child nodes are added in the order
# of addition, i.e., the first child added becomes the left node, and the
# second child will be the second node.
# If only one child is present, then this will be the left child.
def add(child)
raise "Already has two child nodes" if @children.size == 2
super(child)
end
# Returns the left child node. Note that
# left Child == first Child
def leftChild
children.first
end
# Returns the right child node. Note that
# right child == last child unless there is only one child.
# Returns nil if the right child does not exist.
def rightChild
children[1]
end
# Sets the left child. If a previous child existed, it is replaced.
def leftChild=(child)
@children[0] = child
@childrenHash[child.name] = child if child # Assign the name mapping
end
# Sets the right child. If a previous child existed, it is replaced.
def rightChild=(child)
@children[1] = child
@childrenHash[child.name] = child if child # Assign the name mapping
end
# Returns true if this is the left child of its parent. Always returns false
# if this is the root node.
def isLeftChild?
return nil if isRoot?
self == parent.leftChild
end
# Returns true if this is the right child of its parent. Always returns false
# if this is the root node.
def isRightChild?
return nil if isRoot?
self == parent.rightChild
end
# Swaps the left and right children with each other
def swap_children
tempChild = leftChild
self.leftChild= rightChild
self.rightChild= tempChild
end
end
end
# $Log: binarytree.rb,v $
# Revision 1.5 2007/12/18 23:11:29 anupamsg
# Minor documentation changes in the binarytree class.
#
# Revision 1.4 2007/08/30 22:08:58 anupamsg
# Added a new swap_children method for Binary Tree. Also added minor
# documentation and test updates.
#
# Revision 1.3 2007/07/21 03:24:25 anupamsg
# Minor edits to parameter names. User visible functionality does not change.
#
# Revision 1.2 2007/07/18 20:15:06 anupamsg
# Added two predicate methods in BinaryTreeNode to determine whether a node
# is a left or a right node.
#
# Revision 1.1 2007/07/18 19:33:27 anupamsg
# Added a new binary tree implementation.
#