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 DepthFirstIterator<T extends Node> implements Iterator<T> {
038        boolean directed;
039        Graph graph;
040
041        Node[] parent;
042        Iterator<Edge>[] iterator;
043        int depth[];
044        Node next;
045        int maxDepth;
046
047        @SuppressWarnings("unchecked")
048        public DepthFirstIterator(Node startNode, boolean directed) {
049                this.directed = directed;
050                graph = startNode.getGraph();
051                int n = graph.getNodeCount();
052                parent = new Node[n];
053                iterator = new Iterator[n];
054                depth = new int[n];
055
056                int s = startNode.getIndex();
057                for (int i = 0; i < n; i++)
058                        depth[i] = i == s ? 0 : -1;
059                next = startNode;
060        }
061
062        protected void gotoNext() {
063                while (next != null) {
064                        int i = next.getIndex();
065                        while (iterator[i].hasNext()) {
066                                Node neighbor = iterator[i].next().getOpposite(next);
067                                int j = neighbor.getIndex();
068                                if (iterator[j] == null) {
069                                        parent[j] = next;
070                                        iterator[j] = directed ? neighbor.getLeavingEdgeIterator()
071                                                        : neighbor.getEnteringEdgeIterator();
072                                        depth[j] = depth[i] + 1;
073                                        if (depth[j] > maxDepth)
074                                                maxDepth = depth[j];
075                                        next = neighbor;
076                                        return;
077                                }
078                        }
079                        next = parent[i];
080                }
081        }
082
083        public DepthFirstIterator(Node startNode) {
084                this(startNode, true);
085        }
086
087        public boolean hasNext() {
088                return next != null;
089        }
090
091        @SuppressWarnings("unchecked")
092        public T next() {
093                if (next == null)
094                        throw new NoSuchElementException();
095                iterator[next.getIndex()] = directed ? next.getLeavingEdgeIterator()
096                                : next.getEnteringEdgeIterator();
097                Node previous = next;
098                gotoNext();
099                return (T) previous;
100        }
101
102        public void remove() {
103                throw new UnsupportedOperationException(
104                                "This iterator does not support remove");
105        }
106
107        public int getDepthOf(Node node) {
108                return depth[node.getIndex()];
109        }
110
111        public int getDepthMax() {
112                return maxDepth;
113        }
114
115        public boolean tabu(Node node) {
116                return depth[node.getIndex()] != -1;
117        }
118
119        public boolean isDirected() {
120                return directed;
121        }
122}