SingleRouteTraverser.java

/**
 * This file is part of Relation Analyzer for OSM.
 * Copyright (c) 2001 by Adrian Stabiszewski, as@grundid.de
 *
 * Relation Analyzer is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Relation Analyzer 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Relation Analyzer.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.osmtools.ra.traverse;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;

import org.osmtools.ra.AnalyzerException;
import org.osmtools.ra.data.Node;
import org.osmtools.ra.graph.IntersectionNode;

public class SingleRouteTraverser {

	private List<Node> path = new ArrayList<Node>();
	private Collection<IntersectionNode> visitedNodes = new HashSet<IntersectionNode>();
	private IntersectionNode endNode;

	public SingleRouteTraverser(IntersectionNode startNode, IntersectionNode endNode) {
		this.endNode = endNode;
		traverseNodes(startNode);
	}

	public List<Node> getPath() {
		return path;
	}

	private void traverseNodes(IntersectionNode startNode) {
		path.add(startNode.getNode());
		do {
			visitedNodes.add(startNode);
			IntersectionNode nextNode = getNextNode(startNode);

			path.add(nextNode.getNode());
			startNode = nextNode;
		} while (!startNode.equals(endNode));
	}

	private IntersectionNode getNextNode(IntersectionNode startNode) {
		Iterator<IntersectionNode> edgeIterator = startNode.getEdgesIterator();
		IntersectionNode nextNode = edgeIterator.next();

		IntersectionNode possibleEndNode = nextNode.equals(endNode) ? nextNode : null;
		while (visitedNodes.contains(nextNode)) {
			if (edgeIterator.hasNext()) {
				nextNode = edgeIterator.next();
				if (nextNode.equals(endNode))
					possibleEndNode = nextNode;
			}
			else {
				if (nextNode.equals(endNode)) {
					break;
				}
				else if (possibleEndNode != null) {
					nextNode = possibleEndNode;
				}
				else
					throw new AnalyzerException("No way to go. All nodes visited before.");
			}
		}
		return nextNode;
	}
}