package pattpack.tree;

/**
 *  This class implements the leaves of a binary tree.
 */

public class Leaf<E extends Comparable<E>> implements BinaryTree<E> {

    /**
     *  Tests if this binary tree is a leaf.
     *  @return true.
     */
    public boolean isLeaf () { return true; }
    /**
     *  Compute the left child of this binary tree.
     *  @return never, it throws a RuntimeException.
     */
    public BinaryTree<E> left () {
	throw new RuntimeException ("\"left()\" of empty tree");
    }
    /**
     *  Compute the right child of this binary tree.
     *  @return never, it throws a RuntimeException.
     */
    public BinaryTree<E> right () {
	throw new RuntimeException ("\"right()\" of empty tree");
    }
    /**
     *  Compute the root of this binary tree.
     *  @return never, it throws a RuntimeException.
     */
    public E root () {
	throw new RuntimeException ("\"root()\" of empty tree");
    }
    /**
     *  Construct a new tree which is the result of inserting of an element
     *  into in this binary tree.
     *  @param x The element to insert in a tree.
     *  @return A new tree representing this object with a new element
     *               inserted into it.
     */
    public BinaryTree<E> insert (E x) {
	return new Branch<E> (x, new Leaf<E>(), new Leaf<E>() );
    }
    /**
     *  Pretty print this tree (nothing needs to be printed).
     *  @param level The print indentation level (ignored).
     */
    public void print (int level) {}
}