package binaryTree.visitor;

import binaryTree.*;
import ordering.*;

public class OOBSTDeleter implements IVisitor
{
	public final static OOBSTDeleter Singleton = new OOBSTDeleter ();

	private OOBSTDeleter()
	{
		}

	/**
   * Returns null.
	 * @param host satisfies Binary Search Tree Property (BSTP).
	 * @param input an IOrdered.
	 * @return
	 */
	public Object emptyCase(BiTree host, Object input)
	{
		return null;
	}

	/**
    * Returns input if host contains input, otherwise returns null.
	 * @param host satifies BST property
	 * @param input an IOrdered.
	 */
	public Object nonEmptyCase(BiTree host, Object input)
	{
      IOrdered root = (IOrdered)host.getRootDat();
      IOrdered inp = (IOrdered)input;
      int inpCompRoot = inp.compare (root);
      if (inpCompRoot == IOrdered.LESS)
      {
         return host.getLeftSubTree().execute(this, input);
      }
      else if (inpCompRoot == IOrdered.GREATER)
      {
         return host.getRightSubTree().execute(this, input);
      }
		else
      {
         host.getLeftSubTree().execute(LeftDeleter.Singleton, host);
         return input;
      }
	}
}