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Graph implementations for the JUNG project
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/*
 * Created on Oct 18, 2005
 *
 * Copyright (c) 2005, The JUNG Authors 
 *
 * All rights reserved.
 *
 * This software is open-source under the BSD license; see either
 * "license.txt" or
 * https://github.com/jrtom/jung/blob/master/LICENSE for a description.
 */
package edu.uci.ics.jung.graph;

import java.util.Comparator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;

import com.google.common.base.Supplier;
import com.google.common.collect.Ordering;

import edu.uci.ics.jung.graph.util.Pair;

/**
 * An implementation of Graph that is suitable for sparse graphs,
 * orders its vertex and edge collections according to either specified Comparator
 * instances or the natural ordering of their elements, and permits directed, undirected,
 * and parallel edges. 
 * 
 * @author Joshua O'Madadhain
 */
@SuppressWarnings("serial")
public class SortedSparseMultigraph 
    extends OrderedSparseMultigraph
    implements MultiGraph 
{
    /**
     * @param  the vertex type for the graph Supplier
     * @param  the edge type for the graph Supplier
     * @return a {@code Supplier} that creates an instance of this graph type.
     */
	public static  Supplier> getFactory() 
	{ 
		return new Supplier> () 
		{
			public Graph get() 
			{
				return new SortedSparseMultigraph();
			}
		};
	}
    
    /**
     * Comparator used in ordering vertices.  Defaults to util.ComparableComparator
     * if no comparators are specified in the constructor.
     */
    protected Comparator vertex_comparator;

    /**
     * Comparator used in ordering edges.  Defaults to util.ComparableComparator
     * if no comparators are specified in the constructor.
     */
    protected Comparator edge_comparator;
    
    /**
     * Creates a new instance which sorts its vertices and edges according to the 
     * specified {@code Comparator}s.
     * @param vertex_comparator specifies how the vertices are to be compared 
     * @param edge_comparator specifies how the edges are to be compared
     */
    public SortedSparseMultigraph(Comparator vertex_comparator, Comparator edge_comparator)
    {
        this.vertex_comparator = vertex_comparator;
        this.edge_comparator = edge_comparator;
        vertices = new TreeMap>>(vertex_comparator);
        edges = new TreeMap>(edge_comparator);
        directedEdges = new TreeSet(edge_comparator);
    }
    
    /**
     * Creates a new instance which sorts its vertices and edges according to 
     * their natural ordering.
     */
    public SortedSparseMultigraph()
    {
        this(new Ordering(){
			@SuppressWarnings("unchecked")
			public int compare(V v1, V v2) {
				return ((Comparable) v1).compareTo(v2);
			}},
        		new Ordering(){
					@SuppressWarnings("unchecked")
					public int compare(E e1, E e2) {
						return ((Comparable) e1).compareTo(e2);
					}});
    }

    /**
     * Provides a new {@code Comparator} to be used in sorting the vertices.
     * @param vertex_comparator the comparator that defines the new ordering
     */
    public void setVertexComparator(Comparator vertex_comparator)
    {
        this.vertex_comparator = vertex_comparator;
        Map>> tmp_vertices = new TreeMap>>(vertex_comparator);
        for (Map.Entry>> entry : vertices.entrySet())
            tmp_vertices.put(entry.getKey(), entry.getValue());
        this.vertices = tmp_vertices;
    }
    
    @Override
    public boolean addVertex(V vertex) {
        if(vertex == null) {
            throw new IllegalArgumentException("vertex may not be null");
        }
        if (!containsVertex(vertex)) 
        {
            vertices.put(vertex, new Pair>(new TreeSet(edge_comparator), 
                new TreeSet(edge_comparator)));
            return true;
        } 
        else 
        {
        	return false;
        }
    }
}