package rpi.goldsd.container;

/**
 * The <tt>Linkable</tt> interface defines the methods required by any
 * object that can be linked into a linked list or other such linked
 * structure.  Note that the <tt>Linkable</tt> interface defines methods
 * for a doubly-linked structure.  If a singly-linked structure is to be
 * used, the <tt>getPrevious()</tt> and <tt>setPrevious()</tt> methods
 * may be implemented as empty methods.
 *
 * @see ListNode
 * @see LinkedList
 * @version 1.0, 3/15/98
 * @author David Goldschmidt
 */
public interface Linkable
{
  /**
   * Returns a reference to the next element in the list.
   * @return a reference to the next element in the list.
   */
  public Linkable getNext();


  /**
   * Returns a reference to the previous element in the list.
   * @return a reference to the previous element in the list.
   */
  public Linkable getPrevious();


  /**
   * Establishes a link to the next element in the list.
   * @param node a reference to the next element in the list to
   *             be linked to this <tt>Linkable</tt> object.
   */
  public void setNext( Linkable node );


  /**
   * Establishes a link to the previous element in the list.
   * @param node a reference to the previous element in the list
   *             to be linked to this <tt>Linkable</tt> object.
   */
  public void setPrevious( Linkable node );
}