/*
Copyright (c) 1998-2005 The Regents of the University of California
All rights reserved.
Permission is hereby granted, without written agreement and without
license or royalty fees, to use, copy, modify, and distribute this
software and its documentation for any purpose, provided that the above
copyright notice and the following two paragraphs appear in all copies
of this software.
IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
PROVIDED HEREUNDER IS ON AN BASIS, AND THE UNIVERSITY OF
CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
ENHANCEMENTS, OR MODIFICATIONS.
PT_COPYRIGHT_VERSION_2
COPYRIGHTENDKEY
*/
package diva.graph.modular;
/**
* An edge is an object that is contained by a graph and connects
* nodes. An edge has a "head" and a "tail" as if it was directed,
* but also has a method isDirected() that says whether or not the
* edge should be treated as directed (e.g. should there be an arrow
* drawn on the head). An edge has a semantic object that is its
* semantic equivalent in the application and may have a visual object
* which is its syntactic representation in the user interface.
*
* @author Michael Shilman
* @version $Id$
* @Pt.AcceptedRating Red
*/
public interface EdgeModel {
/**
* Return the node at the head of this edge.
*/
public Object getHead(Object edge);
/**
* Return the node at the tail of this edge.
*/
public Object getTail(Object edge);
/**
* Return whether or not this edge is directed.
*/
public boolean isDirected(Object edge);
}