/**********************************************************************
 * $Id: Subgraph.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_SUBGRAPH_H
#define GEOS_PLANARGRAPH_SUBGRAPH_H

#include <geos/export.h>
#include <geos/planargraph/NodeMap.h> // for composition

#include <vector> 

// Forward declarations
namespace geos {
	namespace planargraph { 
		class PlanarGraph;
		class DirectedEdge;
		class Edge;
	}
}

namespace geos {
namespace planargraph { // geos.planargraph

/// A subgraph of a PlanarGraph.
//
/// A subgraph may contain any subset of geomgraph::Edges
/// from the parent graph.
/// It will also automatically contain all geomgraph::DirectedEdge
/// and geomgraph::Node associated with those edges.
/// No new objects are created when edges are added -
/// all associated components must already exist in the parent graph.
///
/// @@ Actually we'll be copying Coordinates in NodeMap.
/// I guess that'll need to be changed soon.
///
class GEOS_DLL Subgraph
{
protected:
	PlanarGraph &parentGraph;
	std::set<Edge*> edges;
	std::vector<const DirectedEdge*> dirEdges;
	NodeMap nodeMap;

public:
	/**
	 * Creates a new subgraph of the given PlanarGraph
	 *
	 * @param parent the parent graph
	 */
	Subgraph(PlanarGraph &parent)
		:
		parentGraph(parent)
		{}

	/**
	 * Gets the {@link PlanarGraph} which this subgraph
	 * is part of.
	 *
	 * @return the parent PlanarGraph
	 */
	PlanarGraph& getParent() const { return parentGraph; }

	/**
	 * Adds an {@link Edge} to the subgraph.
	 * The associated {@link DirectedEdge}s and {@link planarNode}s
	 * are also added.
	 *
	 * @param e the edge to add
	 *
	 * @return a pair with first element being an iterator
	 *         to the Edge in set and second element
	 *	   being a boolean value indicating wheter
	 *	   the Edge has been inserted now or was
	 *	   already in the set.
	 */
	std::pair<std::set<Edge*>::iterator, bool> add(Edge *e);

	/**
	 * Returns an iterator over the DirectedEdge in this graph,
	 * in the order in which they were added.
	 *
	 * @return an iterator over the directed edges
	 *
	 * @see add(Edge)
	 */
	std::vector<const DirectedEdge*>::iterator getDirEdgeBegin() {
		return dirEdges.begin();
	}

	
	/**
	 * Returns an {@link Iterator} over the {@link Edge}s in this
	 * graph, in the order in which they were added.
	 *
	 * @return an iterator over the edges
	 *
	 * @see add(Edge)
	 */
	std::set<Edge*>::iterator edgeBegin() { return edges.begin(); }
	std::set<Edge*>::iterator edgeEnd() { return edges.end(); }

	/**
	 * Returns a iterators over the planarNodesMap::container
	 * in this graph.
	 */
	NodeMap::container::iterator nodeBegin() {
		return nodeMap.begin(); 
	}
	NodeMap::container::const_iterator nodeEnd() const {
		return nodeMap.end(); 
	}
	NodeMap::container::iterator nodeEnd() {
		return nodeMap.end(); 
	}
	NodeMap::container::const_iterator nodeBegin() const {
		return nodeMap.begin(); 
	}

	/**
	 * Tests whether an {@link Edge} is contained in this subgraph
	 * @param e the edge to test
	 * @return <code>true</code> if the edge is contained in this subgraph
	 */
	bool contains(Edge *e) { return (edges.find(e) != edges.end()); }

	
};


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

#endif // GEOS_PLANARGRAPH_SUBGRAPH_H

/**********************************************************************
 * $Log$
 * Revision 1.1  2006/03/21 21:42:54  strk
 * planargraph.h header split, planargraph:: classes renamed to match JTS symbols
 *
 **********************************************************************/

