001/*
002 * Copyright 2006 - 2013
003 *     Stefan Balev     <stefan.balev@graphstream-project.org>
004 *     Julien Baudry    <julien.baudry@graphstream-project.org>
005 *     Antoine Dutot    <antoine.dutot@graphstream-project.org>
006 *     Yoann Pigné      <yoann.pigne@graphstream-project.org>
007 *     Guilhelm Savin   <guilhelm.savin@graphstream-project.org>
008 * 
009 * This file is part of GraphStream <http://graphstream-project.org>.
010 * 
011 * GraphStream is a library whose purpose is to handle static or dynamic
012 * graph, create them from scratch, file or any source and display them.
013 * 
014 * This program is free software distributed under the terms of two licenses, the
015 * CeCILL-C license that fits European law, and the GNU Lesser General Public
016 * License. You can  use, modify and/ or redistribute the software under the terms
017 * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
018 * URL <http://www.cecill.info> or under the terms of the GNU LGPL as published by
019 * the Free Software Foundation, either version 3 of the License, or (at your
020 * option) any later version.
021 * 
022 * This program is distributed in the hope that it will be useful, but WITHOUT ANY
023 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
024 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
025 * 
026 * You should have received a copy of the GNU Lesser General Public License
027 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
028 * 
029 * The fact that you are presently reading this means that you have had
030 * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
031 */
032package org.graphstream.graph;
033
034import java.util.Iterator;
035import java.util.NoSuchElementException;
036
037public class BreadthFirstIterator<T extends Node> implements Iterator<T> {
038        protected boolean directed;
039        protected Graph graph;
040        protected Node[] queue;
041        protected int[] depth;
042        protected int qHead, qTail;
043
044        public BreadthFirstIterator(Node startNode, boolean directed) {
045                this.directed = directed;
046                graph = startNode.getGraph();
047                int n = graph.getNodeCount();
048                queue = new Node[n];
049                depth = new int[n];
050
051                int s = startNode.getIndex();
052                for (int i = 0; i < n; i++)
053                        depth[i] = i == s ? 0 : -1;
054                queue[0] = startNode;
055                qHead = 0;
056                qTail = 1;
057        }
058
059        public BreadthFirstIterator(Node startNode) {
060                this(startNode, true);
061        }
062
063        public boolean hasNext() {
064                return qHead < qTail;
065        }
066
067        @SuppressWarnings("unchecked")
068        public T next() {
069                if (qHead >= qTail)
070                        throw new NoSuchElementException();
071                Node current = queue[qHead++];
072                int level = depth[current.getIndex()] + 1;
073                Iterable<Edge> edges = directed ? current.getEachLeavingEdge()
074                                : current.getEachEdge();
075                for (Edge e : edges) {
076                        Node node = e.getOpposite(current);
077                        int j = node.getIndex();
078                        if (depth[j] == -1) {
079                                queue[qTail++] = node;
080                                depth[j] = level;
081                        }
082                }
083                return (T)current;
084        }
085
086        public void remove() {
087                throw new UnsupportedOperationException(
088                                "This iterator does not support remove");
089        }
090
091        public int getDepthOf(Node node) {
092                return depth[node.getIndex()];
093        }
094
095        public int getDepthMax() {
096                return depth[queue[qTail - 1].getIndex()];
097        }
098
099        public boolean tabu(Node node) {
100                return depth[node.getIndex()] != -1;
101        }
102
103        public boolean isDirected() {
104                return directed;
105        }
106}