/*
* Created on Apr 15, 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.
*/
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 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>Graph</code> that is suitable for sparse graphs
* and permits both directed and undirected edges.
*/
@SuppressWarnings("serial")
public class SparseGraph<V, E> extends AbstractGraph<V, E>
implements Graph<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<Graph<V, E>> getFactory() {
return new Factory<Graph<V, E>>() {
@Override
public Graph<V, E> create() {
return new SparseGraph<V, E>();
}
};
}
protected static final int INCOMING = 0;
protected static final int OUTGOING = 1;
protected static final int INCIDENT = 2;
protected Map<V, Map<V, E>[]> vertex_maps; // Map of vertices to adjacency
// maps of vertices to
// {incoming, outgoing,
// incident} edges
protected Map<E, Pair<V>> directed_edges; // Map of directed edges to
// incident vertex sets
protected Map<E, Pair<V>> undirected_edges; // Map of undirected edges to
// incident vertex sets
/**
* Creates an instance.
*/
public SparseGraph() {
vertex_maps = new HashMap<V, Map<V, E>[]>();
directed_edges = new HashMap<E, Pair<V>>();
undirected_edges = new HashMap<E, Pair<V>>();
}
@Override
public E findEdge(V v1, V v2) {
if (!containsVertex(v1) || !containsVertex(v2)) {
return null;
}
E edge = vertex_maps.get(v1)[OUTGOING].get(v2);
if (edge == null) {
edge = vertex_maps.get(v1)[INCIDENT].get(v2);
}
return edge;
}
@Override
public Collection<E> findEdgeSet(V v1, V v2) {
if (!containsVertex(v1) || !containsVertex(v2)) {
return null;
}
Collection<E> edges = new ArrayList<E>(2);
E e1 = vertex_maps.get(v1)[OUTGOING].get(v2);
if (e1 != null) {
edges.add(e1);
}
E e2 = vertex_maps.get(v1)[INCIDENT].get(v2);
if (e1 != null) {
edges.add(e2);
}
return edges;
}
@Override
public boolean addEdge(E edge, Pair<? extends V> endpoints,
EdgeType edgeType) {
Pair<V> new_endpoints = getValidatedEndpoints(edge, endpoints);
if (new_endpoints == null) {
return false;
}
V v1 = new_endpoints.getFirst();
V v2 = new_endpoints.getSecond();
// undirected edges and directed edges are not considered to be parallel
// to each other,
// so as long as anything that's returned by findEdge is not of the same
// type as
// edge, we're fine
E connection = findEdge(v1, v2);
if (connection != null && getEdgeType(connection) == edgeType) {
return false;
}
if (!containsVertex(v1)) {
this.addVertex(v1);
}
if (!containsVertex(v2)) {
this.addVertex(v2);
}
// map v1 to <v2, edge> and vice versa
if (edgeType == EdgeType.DIRECTED) {
vertex_maps.get(v1)[OUTGOING].put(v2, edge);
vertex_maps.get(v2)[INCOMING].put(v1, edge);
directed_edges.put(edge, new_endpoints);
} else {
vertex_maps.get(v1)[INCIDENT].put(v2, edge);
vertex_maps.get(v2)[INCIDENT].put(v1, edge);
undirected_edges.put(edge, new_endpoints);
}
return true;
}
@Override
public Collection<E> getInEdges(V vertex) {
if (!containsVertex(vertex)) {
return null;
}
// combine directed inedges and undirected
Collection<E> in = new HashSet<E>(
vertex_maps.get(vertex)[INCOMING].values());
in.addAll(vertex_maps.get(vertex)[INCIDENT].values());
return Collections.unmodifiableCollection(in);
}
@Override
public Collection<E> getOutEdges(V vertex) {
if (!containsVertex(vertex)) {
return null;
}
// combine directed outedges and undirected
Collection<E> out = new HashSet<E>(
vertex_maps.get(vertex)[OUTGOING].values());
out.addAll(vertex_maps.get(vertex)[INCIDENT].values());
return Collections.unmodifiableCollection(out);
}
@Override
public Collection<V> getPredecessors(V vertex) {
if (!containsVertex(vertex)) {
return null;
}
// consider directed inedges and undirected
Collection<V> preds = new HashSet<V>(
vertex_maps.get(vertex)[INCOMING].keySet());
preds.addAll(vertex_maps.get(vertex)[INCIDENT].keySet());
return Collections.unmodifiableCollection(preds);
}
@Override
public Collection<V> getSuccessors(V vertex) {
if (!containsVertex(vertex)) {
return null;
}
// consider directed outedges and undirected
Collection<V> succs = new HashSet<V>(
vertex_maps.get(vertex)[OUTGOING].keySet());
succs.addAll(vertex_maps.get(vertex)[INCIDENT].keySet());
return Collections.unmodifiableCollection(succs);
}
@Override
public Collection<E> getEdges(EdgeType edgeType) {
if (edgeType == EdgeType.DIRECTED) {
return Collections.unmodifiableCollection(directed_edges.keySet());
} else if (edgeType == EdgeType.UNDIRECTED) {
return Collections
.unmodifiableCollection(undirected_edges.keySet());
} else {
return null;
}
}
@Override
public Pair<V> getEndpoints(E edge) {
Pair<V> endpoints;
endpoints = directed_edges.get(edge);
if (endpoints == null) {
return undirected_edges.get(edge);
}
return endpoints;
}
@Override
public EdgeType getEdgeType(E edge) {
if (directed_edges.containsKey(edge)) {
return EdgeType.DIRECTED;
} else if (undirected_edges.containsKey(edge)) {
return EdgeType.UNDIRECTED;
} else {
return null;
}
}
@Override
public V getSource(E directed_edge) {
if (getEdgeType(directed_edge) == EdgeType.DIRECTED) {
return directed_edges.get(directed_edge).getFirst();
}
return null;
}
@Override
public V getDest(E directed_edge) {
if (getEdgeType(directed_edge) == EdgeType.DIRECTED) {
return directed_edges.get(directed_edge).getSecond();
}
return null;
}
@Override
public boolean isSource(V vertex, E edge) {
if (!containsVertex(vertex) || !containsEdge(edge)) {
return false;
}
V source = getSource(edge);
if (source != null) {
return source.equals(vertex);
}
return false;
}
@Override
public boolean isDest(V vertex, E edge) {
if (!containsVertex(vertex) || !containsEdge(edge)) {
return false;
}
V dest = getDest(edge);
if (dest != null) {
return dest.equals(vertex);
}
return false;
}
@Override
public Collection<E> getEdges() {
Collection<E> edges = new ArrayList<E>(directed_edges.keySet());
edges.addAll(undirected_edges.keySet());
return Collections.unmodifiableCollection(edges);
}
@Override
public Collection<V> getVertices() {
return Collections.unmodifiableCollection(vertex_maps.keySet());
}
@Override
public boolean containsVertex(V vertex) {
return vertex_maps.containsKey(vertex);
}
@Override
public boolean containsEdge(E edge) {
return directed_edges.containsKey(edge)
|| undirected_edges.containsKey(edge);
}
@Override
public int getEdgeCount() {
return directed_edges.size() + undirected_edges.size();
}
@Override
public int getVertexCount() {
return vertex_maps.size();
}
@Override
public Collection<V> getNeighbors(V vertex) {
if (!containsVertex(vertex)) {
return null;
}
// consider directed edges and undirected edges
Collection<V> neighbors = new HashSet<V>(
vertex_maps.get(vertex)[INCOMING].keySet());
neighbors.addAll(vertex_maps.get(vertex)[OUTGOING].keySet());
neighbors.addAll(vertex_maps.get(vertex)[INCIDENT].keySet());
return Collections.unmodifiableCollection(neighbors);
}
@Override
public Collection<E> getIncidentEdges(V vertex) {
if (!containsVertex(vertex)) {
return null;
}
Collection<E> incident = new HashSet<E>(
vertex_maps.get(vertex)[INCOMING].values());
incident.addAll(vertex_maps.get(vertex)[OUTGOING].values());
incident.addAll(vertex_maps.get(vertex)[INCIDENT].values());
return Collections.unmodifiableCollection(incident);
}
@Override
@SuppressWarnings("unchecked")
public boolean addVertex(V vertex) {
if (vertex == null) {
throw new IllegalArgumentException("vertex may not be null");
}
if (!containsVertex(vertex)) {
vertex_maps.put(vertex, new HashMap[] { new HashMap<V, E>(),
new HashMap<V, E>(), new HashMap<V, E>() });
return true;
}
return false;
}
@Override
public boolean removeVertex(V vertex) {
if (!containsVertex(vertex)) {
return false;
}
// copy to avoid concurrent modification in removeEdge
Collection<E> incident = new ArrayList<E>(getIncidentEdges(vertex));
for (E edge : incident) {
removeEdge(edge);
}
vertex_maps.remove(vertex);
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 maps
if (getEdgeType(edge) == EdgeType.DIRECTED) {
vertex_maps.get(v1)[OUTGOING].remove(v2);
vertex_maps.get(v2)[INCOMING].remove(v1);
directed_edges.remove(edge);
} else {
vertex_maps.get(v1)[INCIDENT].remove(v2);
vertex_maps.get(v2)[INCIDENT].remove(v1);
undirected_edges.remove(edge);
}
return true;
}
@Override
public int getEdgeCount(EdgeType edge_type) {
if (edge_type == EdgeType.DIRECTED) {
return directed_edges.size();
}
if (edge_type == EdgeType.UNDIRECTED) {
return undirected_edges.size();
}
return 0;
}
@Override
public EdgeType getDefaultEdgeType() {
return EdgeType.UNDIRECTED;
}
@Override
public SparseGraph<V, E> newInstance() {
return new SparseGraph<V, E>();
}
}