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/*
 * (C) Copyright 2003-2016, by Barak Naveh and Contributors.
 *
 * JGraphT : a free Java graph-theory library
 *
 * This program and the accompanying materials are dual-licensed under
 * either
 *
 * (a) the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation, or (at your option) any
 * later version.
 *
 * or (per the licensee's choosing)
 *
 * (b) the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation.
 */
package org.jgrapht.graph;

import java.util.*;

import org.jgrapht.*;

/**
 * An undirected graph that is a subgraph on other graph.
 *
 * @param  the graph vertex type
 * @param  the graph edge type
 *
 * @see Subgraph
 */
public class UndirectedSubgraph
    extends Subgraph>
    implements UndirectedGraph
{
    private static final long serialVersionUID = 3256728359772631350L;

    /**
     * Creates a new undirected subgraph.
     *
     * @param base the base (backing) graph on which the subgraph will be based.
     * @param vertexSubset vertices to include in the subgraph. If 
     * null then all vertices are included.
     * @param edgeSubset edges to in include in the subgraph. If 
     * null then all the edges whose vertices found in the graph are included.
     */
    public UndirectedSubgraph(UndirectedGraph base, Set vertexSubset, Set edgeSubset)
    {
        super(base, vertexSubset, edgeSubset);
    }

    /**
     * @see UndirectedGraph#degreeOf(Object)
     */
    @Override
    public int degreeOf(V vertex)
    {
        assertVertexExist(vertex);

        int degree = 0;

        for (E e : getBase().edgesOf(vertex)) {
            if (containsEdge(e)) {
                degree++;

                if (getEdgeSource(e).equals(getEdgeTarget(e))) {
                    degree++;
                }
            }
        }

        return degree;
    }
}

// End UndirectedSubgraph.java