// Textbook fragment 10.09
/** Realization of a dictionary by means of a red-black tree. */
public class RBTree<K,V>
  extends BinarySearchTree<K,V> implements Dictionary<K,V> {
  public RBTree() { super(); }
  public RBTree(Comparator<K> C) { super(C); }
  /** Nested class for the nodes of a red-black tree */
  protected static class RBNode<K,V> extends BTNode<Entry<K,V>> {
    protected boolean isRed;  // we add a color field to a BTNode
    RBNode() {/* default constructor */}
    /** Preferred constructor */
    RBNode(Entry<K,V> element, BTPosition<Entry<K,V>> parent,
           BTPosition<Entry<K,V>> left, BTPosition<Entry<K,V>> right) {
      super(element, parent, left, right);
      isRed = false;
    }
    public boolean isRed()  {return isRed;}
    public void makeRed()  {isRed = true;}
    public void makeBlack()  {isRed = false;}
    public void setColor(boolean color)  {isRed = color;}
  }