package t234;

/**
* This is an object-oriented implementation 2-3-4 trees using the state design pattern.
* The classic discussion for 2-3-4 trees is outlined in Sedgewick's "Algorithms in C++",
* Addison-Wesley 1992, pp. 215-219.  Other elucidating discussions of balanced trees can
* be found in Stubbs/Webre's "Data Structures", and Aho/Hopcroft/Ullman's "Data Structures
* and Algorithms".  For the sake of definiteness, we desing the tree to store Integer
* objects only.
* @since 12/03/00
* @author Dung X. Nguyen, Copyright 2000 - All Rights Reserved.
*/
public class Tree234
{
   /** @SBGen Variable (,,,64)   */
	private ANode234 _rootNode;

   /**
   * Initializes this Tree234 to empty.
   */
   public Tree234 ()
   {
  	   _rootNode = EmptyNode.Singleton;
   }

   /**
   * Initializes this Tree234 to contain exactly one data element, an empty left
   * subtree, and an empty right subtrees.  The subtrees are Tree234.
   <pre>
   This constructor is not intrinsically needed.  It exists as a convenience only.
   </pre>
   * @param n != null.
   */
   public Tree234 (Integer n)
   {
  	   _rootNode = new Node2 (n);
   }

   public final boolean isEmpty ()
   {
      return _rootNode.isEmpty (this);
   }

   /**
   * Inserts an Integer into this Tree234 without duplication.
   * @param n != null.
   */
   public final void insert (Integer n)
   {
	   _rootNode.insert (this,n);
   }

   /**
	 * For debugging purpose.
	 * EXERCISE FOR STUDENTS: Write the toString() method instead.
	 *  Hint: see the binary tree example.
	 */
	public final void draw ()
   {
      drawAtLevel (0);
   }

  ///////////////////////////////////////
  //Not visible outside of package

   Tree234(ANode234 root)
   {
      _rootNode = root;
   }

   Tree234(Tree234 lTree, Integer n, Tree234 rTree)
   {
      _rootNode = new Node2 (lTree, n, rTree);
   }

   final void drawAtLevel (int level)
   {
	   _rootNode.drawAtLevel (level);
   }

   final void changeRoot (ANode234 newRoot)
   {
	   _rootNode = newRoot;
   }

   final ANode234 root()
   {
	   return _rootNode;
   }

   final void insertHelper (Tree234 parent, Integer n)
   {
      _rootNode.insertHelper (parent, this, n);
   }

   final void attach (Tree234 lTree, Integer n, Tree234 rTree)
   {
      _rootNode.attach (this, lTree, n, rTree);
   }
}