org.graphstream.graph.DepthFirstIterator Maven / Gradle / Ivy

/*
 * This file is part of GraphStream .
 * 
 * GraphStream is a library whose purpose is to handle static or dynamic
 * graph, create them from scratch, file or any source and display them.
 * 
 * This program is free software distributed under the terms of two licenses, the
 * CeCILL-C license that fits European law, and the GNU Lesser General Public
 * License. You can  use, modify and/ or redistribute the software under the terms
 * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
 * URL  or under the terms of the GNU LGPL as published by
 * the Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see .
 * 
 * The fact that you are presently reading this means that you have had
 * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
 */

/**
 * @since 2009-02-19
 * 
 * @author Guilhelm Savin 
 * @author Yoann Pigné 
 * @author Antoine Dutot 
 * @author Stefan Balev 
 * @author Hicham Brahimi 
 */
package org.graphstream.graph;

import java.util.Iterator;
import java.util.NoSuchElementException;

public class DepthFirstIterator implements Iterator {
	boolean directed;
	Graph graph;

	Node[] parent;
	Iterator[] iterator;
	int depth[];
	Node next;
	int maxDepth;

	@SuppressWarnings("unchecked")
	public DepthFirstIterator(Node startNode, boolean directed) {
		this.directed = directed;
		graph = startNode.getGraph();
		int n = graph.getNodeCount();
		parent = new Node[n];
		iterator = new Iterator[n];
		depth = new int[n];

		int s = startNode.getIndex();
		for (int i = 0; i < n; i++)
			depth[i] = i == s ? 0 : -1;
		next = startNode;
	}

	protected void gotoNext() {
		while (next != null) {
			int i = next.getIndex();
			while (iterator[i].hasNext()) {
				Node neighbor = iterator[i].next().getOpposite(next);
				int j = neighbor.getIndex();
				if (iterator[j] == null) {
					parent[j] = next;
					iterator[j] = directed ? neighbor.leavingEdges().iterator() : neighbor.enteringEdges().iterator();
					depth[j] = depth[i] + 1;
					if (depth[j] > maxDepth)
						maxDepth = depth[j];
					next = neighbor;
					return;
				}
			}
			next = parent[i];
		}
	}

	public DepthFirstIterator(Node startNode) {
		this(startNode, true);
	}

	public boolean hasNext() {
		return next != null;
	}

	public Node next() {
		if (next == null)
			throw new NoSuchElementException();
		iterator[next.getIndex()] = directed ? next.leavingEdges().iterator() : next.enteringEdges().iterator();
		Node previous = next;
		gotoNext();
		return previous;
	}

	public void remove() {
		throw new UnsupportedOperationException("This iterator does not support remove");
	}

	public int getDepthOf(Node node) {
		return depth[node.getIndex()];
	}

	public int getDepthMax() {
		return maxDepth;
	}

	public boolean tabu(Node node) {
		return depth[node.getIndex()] != -1;
	}

	public boolean isDirected() {
		return directed;
	}
}