Class binaryTree.NullNode

class NullNode
extends binaryTree.ANode
Represents the empty state of a BiTree. Uses the singleton pattern to model the uniqueness of "emptiness".

Author:
Dung X. Nguyen - Copyright 1999 - All rights reserved.

Variable Index

o Singleton
Singleton pattern

Constructor Index

o NullNode ()

Method Index

o execute (IVisitor, Object, BiTree)
Calls the visitor's nullCase () method to execute the visiting algorithm
o getLeftSubTree (BiTree)
Throws java
o getRightSubTree (BiTree)
Throws java
o getRootDat (BiTree)
Throws java
o insertRoot (Object, BiTree)
Asks the parent tree to set the root node to a new DatNode containing dat,
o remOurParent (BiTree, BiTree)
Removes and return the root element of the grandparent of this node,
o remParent (BiTree, BiTree, BiTree)
Removes and return the root element of the grandparent of this node,
o remRoot (BiTree)
Throws java
o setLeftSubTree (BiTree, BiTree)
Throws java
o setRightSubTree (BiTree, BiTree)
Throws java
o setRootDat (Object, BiTree)
Throws java

Variables

o Singleton 
public static final NullNode Singleton
Singleton pattern.

Constructors

o NullNode 
private  NullNode()

Methods

o getRootDat 
Object getRootDat(BiTree parent)
Throws java.util.NoSuchElementException.

o setRootDat 
void setRootDat(Object dat, BiTree parent)
Throws java.util.NoSuchElementException.

o getLeftSubTree 
BiTree getLeftSubTree(BiTree parent)
Throws java.util.NoSuchElementException.

o getRightSubTree 
BiTree getRightSubTree(BiTree parent)
Throws java.util.NoSuchElementException.

o setLeftSubTree 
void setLeftSubTree(BiTree biTree, BiTree parent)
Throws java.util.NoSuchElementException.

o setRightSubTree 
void setRightSubTree(BiTree biTree, BiTree parent)
Throws java.util.NoSuchElementException.

o insertRoot 
void insertRoot(Object dat, BiTree parent)
Asks the parent tree to set the root node to a new DatNode containing dat, resulting in a state change from empty to non-empty.

Parameters:
dat -
parent - the context of this state.
o remRoot 
Object remRoot(BiTree parent)
Throws java.util.NoSuchElementException.

o remParent 
Object remParent(BiTree aunt, BiTree grandPo, BiTree mom)
Removes and return the root element of the grandparent of this node, asking the sibbling of the parent tree to do it if necessary.

Parameters:
aunt - the sibbling of the parent of this node.
grandPo - the grand parent of this node.
mom - the parent (i.e. context) of this node.
Returns:
the root data of the grandparent of this node.
o remOurParent 
Object remOurParent(BiTree grandParent, BiTree parent)
Removes and return the root element of the grandparent of this node, knowing the sibbling of the parent tree is empty.

Parameters:
grandParent - the grand parent of this BiTree.
parent - the context of this node.
Returns:
the root data of the grandparent of this node.
o execute 
Object execute(IVisitor algo, Object input, BiTree parent)
Calls the visitor's nullCase () method to execute the visiting algorithm.

Parameters:
algo - the visiting algorithm
input - the input the algorithm needs.
parent - the context of this node.
Returns:
the output for the nullCase() of the algorithm.