// Source code example for "A Practical Introduction
// to Data Structures and Algorithm Analysis"
// by Clifford A. Shaffer, Prentice Hall, 1998.
// Copyright 1998 by Clifford A. Shaffer

interface GTNode {                    // General tree node ADT
  public Object value();              // Return the value
  public boolean isLeaf();            // TRUE if this node is a leaf
  public GTNode parent();             // Return the parent
  public GTNode leftmost_child();     // Return the leftmost child
  public GTNode right_sibling();      // Return the right sibling
  public void setValue(Object value); // Set the value
  public void setParent(GTNode par);  // Set the parent
  public void insert_first(GTNode n); // Add a new leftmost child
  public void insert_next(GTNode n);  // Insert a new right sibling
  public void remove_first();         // Remove the leftmost child
  public void remove_next();          // Remove the right sibling
} // interface GTNode