/*

  * Created on Oct 17, 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.Collection;

 import java.util.Collections;

 import java.util.LinkedHashMap;

 import java.util.LinkedHashSet;

 import java.util.Set;

 import org.apache.commons.collections15.Factory;

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

 /**

  * An implementation of <code>DirectedGraph</code>, suitable for sparse graphs, 

  * that orders its vertex and edge collections

  * according to insertion time.

  */

 @SuppressWarnings("serial")

 public class DirectedOrderedSparseMultigraph<V,E> 

     extends DirectedSparseMultigraph<V,E>

     implements DirectedGraph<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<DirectedGraph<V,E>> getFactory() {

                 return new Factory<DirectedGraph<V,E>> () {

                         public DirectedGraph<V,E> create() {

                                 return new DirectedOrderedSparseMultigraph<V,E>();

                         }

                 };

         }

     /**

      * Creates a new instance.

      */

     public DirectedOrderedSparseMultigraph() {

         vertices = new LinkedHashMap<V, Pair<Set<E>>>();

         edges = new LinkedHashMap<E, Pair<V>>();

     }

     @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<Set<E>>(new LinkedHashSet<E>(), new LinkedHashSet<E>()));

             return true;

         } else {

             return false;

         }

     }

     @Override

     public Collection<V> getPredecessors(V vertex) {

         if (!containsVertex(vertex)) 

             return null;

         Set<V> preds = new LinkedHashSet<V>();

         for (E edge : getIncoming_internal(vertex))

             preds.add(this.getSource(edge));

         return Collections.unmodifiableCollection(preds);

     }

     @Override

     public Collection<V> getSuccessors(V vertex) {

         if (!containsVertex(vertex)) 

             return null;

         Set<V> succs = new LinkedHashSet<V>();

         for (E edge : getOutgoing_internal(vertex))

             succs.add(this.getDest(edge));

         return Collections.unmodifiableCollection(succs);

     }

     @Override

     public Collection<V> getNeighbors(V vertex) {

         if (!containsVertex(vertex)) 

             return null;

         Collection<V> neighbors = new LinkedHashSet<V>();

         for (E edge : getIncoming_internal(vertex))

             neighbors.add(this.getSource(edge));

         for (E edge : getOutgoing_internal(vertex))

             neighbors.add(this.getDest(edge));

         return Collections.unmodifiableCollection(neighbors);

     }

     @Override

     public Collection<E> getIncidentEdges(V vertex) {

         if (!containsVertex(vertex)) 

             return null;

         Collection<E> incident = new LinkedHashSet<E>();

         incident.addAll(getIncoming_internal(vertex));

         incident.addAll(getOutgoing_internal(vertex));

         return incident;

     }

 }