edu.uci.ics.jung.graph.UndirectedSparseGraph Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jung-graph-impl Show documentation
Graph implementations for the JUNG project
There is a newer version: 2.1.1
/*
 * Created on Apr 1, 2007
 *
 * Copyright (c) 2007, 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.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import com.google.common.base.Supplier;

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

/**
 * An implementation of UndirectedGraph that is suitable
 * for sparse graphs.
 */
@SuppressWarnings("serial")
public class UndirectedSparseGraph extends AbstractTypedGraph
        implements UndirectedGraph
{

    /**
     * @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 UndirectedGraph get() {
                return new UndirectedSparseGraph();
            }
        };
    }

    protected Map> vertices; // Map of vertices to adjacency maps of vertices to incident edges
    protected Map> edges;    // Map of edges to incident vertex sets

    /**
     * Creates an instance.
     */
    public UndirectedSparseGraph() {
    	super(EdgeType.UNDIRECTED);
        vertices = new HashMap>();
        edges = new HashMap>();
    }

    @Override
    public boolean addEdge(E edge, Pair endpoints, EdgeType edgeType)
    {
    	this.validateEdgeType(edgeType);
        Pair new_endpoints = getValidatedEndpoints(edge, endpoints);
        if (new_endpoints == null)
            return false;
        
        V v1 = new_endpoints.getFirst();
        V v2 = new_endpoints.getSecond();
        
        if (findEdge(v1, v2) != null)
            return false;
        
        edges.put(edge, new_endpoints);

        if (!vertices.containsKey(v1))
            this.addVertex(v1);
        
        if (!vertices.containsKey(v2))
            this.addVertex(v2);
        
        // map v1 to  and vice versa
        vertices.get(v1).put(v2, edge);
        vertices.get(v2).put(v1, edge);

        return true;
    }

    public Collection getInEdges(V vertex)
    {
        return this.getIncidentEdges(vertex);
    }

    public Collection getOutEdges(V vertex)
    {
        return this.getIncidentEdges(vertex);
    }

    public Collection getPredecessors(V vertex)
    {
        return this.getNeighbors(vertex);
    }

    public Collection getSuccessors(V vertex)
    {
        return this.getNeighbors(vertex);
    }

    @Override
    public E findEdge(V v1, V v2)
    {
        if (!containsVertex(v1) || !containsVertex(v2))
            return null;
        return vertices.get(v1).get(v2);
    }
    
    @Override
    public Collection findEdgeSet(V v1, V v2)
    {
        if (!containsVertex(v1) || !containsVertex(v2))
            return null;
        ArrayList edge_collection = new ArrayList(1);
//        if (!containsVertex(v1) || !containsVertex(v2))
//            return edge_collection;
        E e = findEdge(v1, v2);
        if (e == null)
            return edge_collection;
        edge_collection.add(e);
        return edge_collection;
    }
    
    public Pair getEndpoints(E edge)
    {
        return edges.get(edge);
    }

    public V getSource(E directed_edge)
    {
        return null;
    }

    public V getDest(E directed_edge)
    {
        return null;
    }

    public boolean isSource(V vertex, E edge)
    {
        return false;
    }

    public boolean isDest(V vertex, E edge)
    {
        return false;
    }

    public Collection getEdges()
    {
        return Collections.unmodifiableCollection(edges.keySet());
    }

    public Collection getVertices()
    {
        return Collections.unmodifiableCollection(vertices.keySet());
    }

    public boolean containsVertex(V vertex)
    {
        return vertices.containsKey(vertex);
    }

    public boolean containsEdge(E edge)
    {
        return edges.containsKey(edge);
    }

    public int getEdgeCount()
    {
        return edges.size();
    }

    public int getVertexCount()
    {
        return vertices.size();
    }

    public Collection getNeighbors(V vertex)
    {
        if (!containsVertex(vertex))
            return null;
        return Collections.unmodifiableCollection(vertices.get(vertex).keySet());
    }

    public Collection getIncidentEdges(V vertex)
    {
        if (!containsVertex(vertex))
            return null;
        return Collections.unmodifiableCollection(vertices.get(vertex).values());
    }

    public boolean addVertex(V vertex)
    {
        if(vertex == null) {
            throw new IllegalArgumentException("vertex may not be null");
        }
        if (!containsVertex(vertex)) {
            vertices.put(vertex, new HashMap());
            return true;
        } else {
            return false;
        }
    }

    public boolean removeVertex(V vertex)
    {
        if (!containsVertex(vertex))
            return false;

        // iterate over copy of incident edge collection
        for (E edge : new ArrayList(vertices.get(vertex).values()))
            removeEdge(edge);
        
        vertices.remove(vertex);
        return true;
    }

    public boolean removeEdge(E edge)
    {
        if (!containsEdge(edge))
            return false;
        
        Pair endpoints = getEndpoints(edge);
        V v1 = endpoints.getFirst();
        V v2 = endpoints.getSecond();
        
        // remove incident vertices from each others' adjacency maps
        vertices.get(v1).remove(v2);
        vertices.get(v2).remove(v1);

        edges.remove(edge);
        return true;
    }
}