/**
 * A simple binary tree.  Most of the manipulation is done via
 * BinaryTreeCursors.
 *
 * @author Samuel A. Rebelsky
 * @version 1.0 of April 1999
 */
public interface BinaryTree {
  // +---------+-------------------------------------------------
  // | Methods |
  // +---------+

  /**
   * Determine the number of elements in the tree.
   * Pre: The tree is initialized.
   * Post: Returns the number of elements in the tree.
   */
  public int size();

  /**
   * Determine the depth of the tree.
   * Pre: The tree is initialized and nonempty.
   * Post: Returns the depth of the tree.
   */
  public int depth();

  /**
   * Create a new cursor at the root of the tree.
   * Pre: The tree is initialized and nonempty.
   * Post: Returns a cursor at the root of the tree.
   */
  public BinaryTreeCursor rootCursor();

  /**
   * Set the value at the root of the tree. 
   * Pre: The tree is initialized and empty.
   * Post: The value at the root of the tree is newValue.
   */
  public void setRoot(Object newValue);

} // interface BinaryTree