package t234;

/**
* Represents the abstract state of a 2-3-4 tree.
* @since 12/03/00
* @author Dung X. Nguyen, Copyright 2000 - All Rights Reserved.
*/

abstract class ANode234
{
   /**
   * Checks the owner tree for emptiness.
   <pre>
   EXERCISE FOR STUDENTS: Remove this isEmpty method and rewrite the insertion algorithm
   without checking for emptiness.
   </pre>
   */
   abstract boolean isEmpty (Tree234 owner);

   /**
   * Inserts an Integer into the owner without duplication.
   * @param owner the owner of this ANode234.
   * @param n data object to be inserted.
   */
   abstract void insert (Tree234 owner, Integer n);


   /**
   * Help insert an Integer into the owner, reconnecting the owner's parent subtrees if needed.
   * Called from insert.
   * @param ownerPo the parent tree of the owner tree.
   * @param owner the owner of this ANode234.
   * @param n data object to be inserted.
   */
   abstract void insertHelper (Tree234 ownerPo, Tree234 owner, Integer n);

   /**
   * Adds a data element with its left and right subtrees to this ANode234
   * and re-attaches it to the owner tree.
   * @param owner
   * @param lTree a Tree234 whose elmements are less than n.
   * @param n the data element to be added.
   * @param rTree a Tree234 whose elements are greater than n.
   */
   abstract void attach (Tree234 owner, Tree234 lTree, Integer n, Tree234 rTree);
   
   abstract void drawRootAndSubtrees (int level);

   final void drawAtLevel (int level)  //invariant behavior
   {
  	   drawSpaces (level);
  	   drawRootAndSubtrees (level);
   }

   final void drawSpaces (int n)		//invariant behavior
   {
  	   for (int i = 0; i < n; i++)
  	   System.out.print ("   ");
   }
}