package binaryTree.visitor;

import binaryTree.BiTree;

/**
 * Represents all extrinsic algorithms on a <code>BiTree<code> as a visitor to the
 * the BiTree host structure.  The BiTree host will make the appropriate call on
 * this IVisitor's methods.
 * @author Dung X. Nguyen - Copyright 1999 - All rights reserved.
 * @dependency binaryTree.BiTree 
 * @dependency binaryTree.BiTree 
 */
public abstract interface IVisitor
{
	/**
    * Called by the host when the host is empty.
	 * @param host
	 * @param input the input needed for this IVisitor to perform its task.
	 */
	public abstract Object nullCase(BiTree host, Object input);

	/**
    * Called by the host when the host is not empty.
	 * @param host
	 * @param input the input needed for this IVisitor to perform its task.
	 */
	public abstract Object nonNullCase(BiTree host, Object input);
}