001/* Copyright (C) 2013 TU Dortmund
002 * This file is part of AutomataLib, http://www.automatalib.net/.
003 * 
004 * AutomataLib is free software; you can redistribute it and/or
005 * modify it under the terms of the GNU Lesser General Public
006 * License version 3.0 as published by the Free Software Foundation.
007 * 
008 * AutomataLib is distributed in the hope that it will be useful,
009 * but WITHOUT ANY WARRANTY; without even the implied warranty of
010 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
011 * Lesser General Public License for more details.
012 * 
013 * You should have received a copy of the GNU Lesser General Public
014 * License along with AutomataLib; if not, see
015 * http://www.gnu.de/documents/lgpl.en.html.
016 */
017package net.automatalib.graphs;
018
019import java.util.Collection;
020
021/**
022 * Interface for bidirectional graph. A bidirectional graph is conceptually the same as
023 * a normal (directed) graph, but provides direct access to not only the outgoing, but also
024 * the incoming edges of each state.
025 * 
026 * @author Malte Isberner <malte.isberner@gmail.com>
027 *
028 * @param <N> node class
029 * @param <E> edge class
030 */
031public interface BidirectionalGraph<N, E> extends Graph<N, E> {
032        /**
033         * Retrieves the incoming edges of a given node.
034         * @param node the node
035         * @return all incoming edges of the specified node.
036         */
037        public Collection<E> getIncomingEdges(N node);
038        
039        /**
040         * Retrieves the source node of a given edge.
041         * @param edge the edge
042         * @return the source node of the given edge
043         */
044        public N getSource(E edge);
045}