package binaryTree.visitor;

import binaryTree.BiTree;

/**
 * Returns the subtree of the host with the min value in the root if the tree is not empty,
 otherwise returns the host itself.
 */
public class MinTreeFinder implements IVisitor
{
	/** @SBGen Singleton Variable   */
	public final static MinTreeFinder Singleton = new MinTreeFinder ();

	/** @SBGen Constructor   */
	private MinTreeFinder()
	{
	}

	/**
	 * @param host satisfies the binary search tree property.
	 * @param input == null, not used.
	 * @return host
	 */
	public Object nullCase(BiTree host, Object input)
	{
		return host;
	}

	/**
	 * @param host satisfies the binary search tree property.
	 * @param input == null, not used.
	 * @return subtree with minimum root.
	 */
	public Object nonNullCase(BiTree host, Object input)
	{
      Boolean isLeftEmpty = (Boolean)host.getLeftSubTree().execute (EmptyChecker.Singleton, null);
		return isLeftEmpty.booleanValue()? host: host.getLeftSubTree ().execute (this, null);
	}
}