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 design the tree to store Integer only.
* @since 11/13/01
* @author Dung X. Nguyen, Copyright 2001 - 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.
    
    This constructor is not intrinsically needed.  It exists as a convenience only.
    

    * @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);
    }
}