/*
* Created on Mar 6, 2007
*
* Copyright (c) 2007, the JUNG Project and the Regents of the University
* of California
* All rights reserved.
*
* This software is open-source under the BSD license; see either
* "license.txt" or
* http://jung.sourceforge.net/license.txt for a description.
*/
/*
* Created on Oct 18, 2005
*
* Copyright (c) 2005, the JUNG Project and the Regents of the University
* of California
* All rights reserved.
*
* This software is open-source under the BSD license; see either
* "license.txt" or
* http://jung.sourceforge.net/license.txt 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.HashSet;
import java.util.Map;
import java.util.Set;
import org.apache.commons.collections15.Factory;
import edu.uci.ics.jung.graph.util.EdgeType;
import edu.uci.ics.jung.graph.util.Pair;
/**
* An implementation of <code>UndirectedGraph</code> that is suitable for sparse
* graphs and permits parallel edges.
*/
@SuppressWarnings("serial")
public class UndirectedSparseMultigraph<V, E> extends AbstractTypedGraph<V, E>
implements UndirectedGraph<V, E>, MultiGraph<V, E> {
/**
* Returns a {@code Factory} that creates an instance of this graph type.
*
* @param <V>
* the vertex type for the graph factory
* @param <E>
* the edge type for the graph factory
*/
public static <V, E> Factory<UndirectedGraph<V, E>> getFactory() {
return new Factory<UndirectedGraph<V, E>>() {
@Override
public UndirectedGraph<V, E> create() {
return new UndirectedSparseMultigraph<V, E>();
}
};
}
protected Map<V, Set<E>> vertices; // Map of vertices to adjacency sets
protected Map<E, Pair<V>> edges; // Map of edges to incident vertex sets
/**
* Creates a new instance.
*/
public UndirectedSparseMultigraph() {
super(EdgeType.UNDIRECTED);
vertices = new HashMap<V, Set<E>>();
edges = new HashMap<E, Pair<V>>();
}
@Override
public Collection<E> getEdges() {
return Collections.unmodifiableCollection(edges.keySet());
}
@Override
public Collection<V> getVertices() {
return Collections.unmodifiableCollection(vertices.keySet());
}
@Override
public boolean containsVertex(V vertex) {
return vertices.keySet().contains(vertex);
}
@Override
public boolean containsEdge(E edge) {
return edges.keySet().contains(edge);
}
protected Collection<E> getIncident_internal(V vertex) {
return vertices.get(vertex);
}
@Override
public boolean addVertex(V vertex) {
if (vertex == null) {
throw new IllegalArgumentException("vertex may not be null");
}
if (!containsVertex(vertex)) {
vertices.put(vertex, new HashSet<E>());
return true;
}
return false;
}
@Override
public boolean removeVertex(V vertex) {
if (!containsVertex(vertex)) {
return false;
}
for (E edge : new ArrayList<E>(getIncident_internal(vertex))) {
removeEdge(edge);
}
vertices.remove(vertex);
return true;
}
@Override
public boolean addEdge(E edge, V v1, V v2, EdgeType edgeType) {
return addEdge(edge, new Pair<V>(v1, v2), edgeType);
}
@Override
public boolean addEdge(E edge, Pair<? extends V> endpoints,
EdgeType edge_type) {
validateEdgeType(edge_type);
Pair<V> new_endpoints = getValidatedEndpoints(edge, endpoints);
if (new_endpoints == null) {
return false;
}
V v1 = endpoints.getFirst();
V v2 = endpoints.getSecond();
edges.put(edge, new_endpoints);
if (!containsVertex(v1)) {
this.addVertex(v1);
}
if (!containsVertex(v2)) {
this.addVertex(v2);
}
vertices.get(v1).add(edge);
vertices.get(v2).add(edge);
return true;
}
@Override
public boolean removeEdge(E edge) {
if (!containsEdge(edge)) {
return false;
}
Pair<V> endpoints = getEndpoints(edge);
V v1 = endpoints.getFirst();
V v2 = endpoints.getSecond();
// remove edge from incident vertices' adjacency sets
vertices.get(v1).remove(edge);
vertices.get(v2).remove(edge);
edges.remove(edge);
return true;
}
@Override
public Collection<E> getInEdges(V vertex) {
return this.getIncidentEdges(vertex);
}
@Override
public Collection<E> getOutEdges(V vertex) {
return this.getIncidentEdges(vertex);
}
@Override
public Collection<V> getPredecessors(V vertex) {
return this.getNeighbors(vertex);
}
@Override
public Collection<V> getSuccessors(V vertex) {
return this.getNeighbors(vertex);
}
@Override
public Collection<V> getNeighbors(V vertex) {
if (!containsVertex(vertex)) {
return null;
}
Set<V> neighbors = new HashSet<V>();
for (E edge : getIncident_internal(vertex)) {
Pair<V> endpoints = this.getEndpoints(edge);
V e_a = endpoints.getFirst();
V e_b = endpoints.getSecond();
if (vertex.equals(e_a)) {
neighbors.add(e_b);
} else {
neighbors.add(e_a);
}
}
return Collections.unmodifiableCollection(neighbors);
}
@Override
public Collection<E> getIncidentEdges(V vertex) {
if (!containsVertex(vertex)) {
return null;
}
return Collections.unmodifiableCollection(getIncident_internal(vertex));
}
@Override
public E findEdge(V v1, V v2) {
if (!containsVertex(v1) || !containsVertex(v2)) {
return null;
}
for (E edge : getIncident_internal(v1)) {
Pair<V> endpoints = this.getEndpoints(edge);
V e_a = endpoints.getFirst();
V e_b = endpoints.getSecond();
if ((v1.equals(e_a) && v2.equals(e_b))
|| (v1.equals(e_b) && v2.equals(e_a))) {
return edge;
}
}
return null;
}
@Override
public Pair<V> getEndpoints(E edge) {
return edges.get(edge);
}
@Override
public V getDest(E directed_edge) {
return null;
}
@Override
public V getSource(E directed_edge) {
return null;
}
@Override
public boolean isDest(V vertex, E edge) {
return false;
}
@Override
public boolean isSource(V vertex, E edge) {
return false;
}
@Override
public int getEdgeCount() {
return edges.size();
}
@Override
public int getVertexCount() {
return vertices.size();
}
@Override
public UndirectedSparseMultigraph<V, E> newInstance() {
return new UndirectedSparseMultigraph<V, E>();
}
}