org.jgrapht.graph.AsUnweightedGraph Maven / Gradle / Ivy
/*
* (C) Copyright 2018, by Lukas Harzenetter and Contributors.
*
* JGraphT : a free Java graph-theory library
*
* See the CONTRIBUTORS.md file distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0, or the
* GNU Lesser General Public License v2.1 or later
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html.
*
* SPDX-License-Identifier: EPL-2.0 OR LGPL-2.1-or-later
*/
package org.jgrapht.graph;
import org.jgrapht.*;
import java.io.*;
import java.util.*;
/**
* Provides an unweighted view on a graph.
*
* Algorithms designed for unweighted graphs should also work on weighted graphs. This class
* emulates an unweighted graph based on a weighted one by returning Graph.DEFAULT_EDGE_WEIGHT
* for each edge weight. The underlying weighted graph is provided at the constructor.
* Modifying operations (adding/removing vertexes/edges) are also passed through to the underlying
* weighted graph. As edge weight, Graph.DEFAULT_EDGE_WEIGHT is used. Setting an edge weight is not
* supported. The edges are not modified. So, if an edge is asked for, the one from the underlying
* weighted graph is returned. In case the underlying graph is serializable, this one is
* serializable, too.
*
* @param the graph vertex type
* @param the graph edge type
*/
public class AsUnweightedGraph
extends
GraphDelegator
implements
Serializable,
Graph
{
private static final long serialVersionUID = -5186421272597767751L;
private static final String EDGE_WEIGHT_IS_NOT_SUPPORTED = "Edge weight is not supported";
/**
* Constructor for AsUnweightedGraph.
*
* @param g the backing directed graph over which an undirected view is to be created.
* @throws NullPointerException if the graph is null
*/
public AsUnweightedGraph(Graph g)
{
super(Objects.requireNonNull(g));
}
@Override
public double getEdgeWeight(E e)
{
return Graph.DEFAULT_EDGE_WEIGHT;
}
@Override
public void setEdgeWeight(E e, double weight)
{
throw new UnsupportedOperationException(EDGE_WEIGHT_IS_NOT_SUPPORTED);
}
@Override
public GraphType getType()
{
return super.getType().asUnweighted();
}
}