package t234;

/**
 * Represents the abstract state of a 2-3-4 tree.
 *
 * @since 04/18/01
 * @author Dung X. Nguyen, Copyright 2000 - All Rights Reserved.
 * @author Alan L. Cox
 */

abstract class ANode234
{
  /**
   * Checks the owner tree for emptiness.
   *
   * EXERCISE FOR STUDENTS: Remove this isEmpty method and rewrite the
   *  insertion algorithm without checking for emptiness.
   */
  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 reattaches 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("   ");
  }
}