/**
 * Very simple dictionaries that map keys to values.
 *
 * @author Samuel A. Rebelsky
 * @version 1.0 of November 1999
 */
public interface Dictionary {
  /**
   * Add an entry to the dictionary.
   * Pre: The key and value are non-null.
   * Pre: The key can be compared to other values in the dictionary.
   * Post: Subsequent calls to get(key) will return value.
   *
   * @exception Exception
   *   If the key cannot be compared.
   */
  public void put(Object key, Object value)
    throws Exception;

  /**
   * Look up an entry in the dictionary.
   * Pre: The key is non-null.
   * Pre: The key can be compared to other values in the dictionary.
   * Post: Returns the value most recently "put" with the key.  
   *
   * @exception Exception
   *   If the key cannot be compared or there is no such entry.
   */
  public Object get(Object key)
    throws Exception;

} // interface Dictionary