/*
06/25/97  DXN

This file contains the code for the abstract class ANode234 which represents
the abstract state of a 2-3-4 tree.

Copyright 1997,  Dung X. Nguyen - All Rights Reserved.
*/

abstract class ANode234
{
  abstract boolean isEmpty ();
  abstract void insert (Tree234 parent, Integer n);
  abstract void insertHelper (Tree234 grandPo, Tree234 parent, Integer n);
  abstract void attach (Tree234 parent, 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 ("   ");
  }
}