/**********************************************************************
 * $Id: ConnectedSubgraphFinder.h 2556 2009-06-06 22:22:28Z strk $
 *
 * GEOS - Geometry Engine Open Source
 * http://geos.refractions.net
 *
 * Copyright (C) 2001-2002 Vivid Solutions Inc.
 * Copyright (C) 2005-2006 Refractions Research Inc.
 *
 * This is free software; you can redistribute and/or modify it under
 * the terms of the GNU Lesser General Public Licence as published
 * by the Free Software Foundation. 
 * See the COPYING file for more information.
 *
 **********************************************************************/

#ifndef GEOS_PLANARGRAPH_ALGO_CONNECTEDSUBGRAPHFINDER_H
#define GEOS_PLANARGRAPH_ALGO_CONNECTEDSUBGRAPHFINDER_H

#include <geos/export.h>
#include <geos/planargraph/PlanarGraph.h> // for inlines

#include <stack>
#include <vector>

// Forward declarations
namespace geos {
	namespace planargraph { 
		class PlanarGraph;
		class Subgraph;
		class Node;
	}
}

namespace geos {
namespace planargraph { // geos::planargraph
namespace algorithm { // geos::planargraph::algorithm

/** \brief
 * Finds all connected {@link Subgraph}s of a PlanarGraph.
 * 
 * <b>Note:</b> uses the <code>isVisited</code> flag on the nodes.
 */
class GEOS_DLL ConnectedSubgraphFinder
{
private:
	PlanarGraph& graph;

	/// Returns a newly allocated Subgraph
	Subgraph* findSubgraph(Node* node);


	/**
	 * Adds all nodes and edges reachable from this node to the subgraph.
	 * Uses an explicit stack to avoid a large depth of recursion.
	 *
	 * @param node a node known to be in the subgraph
	 */
	void addReachable(Node* node, Subgraph* subgraph);

	/**
	 * Adds the argument node and all its out edges to the subgraph.
	 * @param node the node to add
	 * @param nodeStack the current set of nodes being traversed
	 */
	void addEdges(Node* node, std::stack<Node *>& nodeStack,
			Subgraph* subgraph);

public:

	ConnectedSubgraphFinder(PlanarGraph& newGraph)
		:
		graph(newGraph)
		{}

	/// \brief
	/// Store newly allocated connected Subgraphs into the
	/// given std::vector
	///
	/// Caller take responsibility in releasing memory associated
	/// with the subgraphs themself.
	///
	///
	void getConnectedSubgraphs(std::vector<Subgraph *>& dest);

};

} // namespace geos::planargraph::algorithm
} // namespace geos::planargraph
} // namespace geos

#endif // GEOS_PLANARGRAPH_ALGO_CONNECTEDSUBGRAPHFINDER_H

