#ifndef EDGE_MAP_BASE_H

#define EDGE_MAP_BASE_H

/**

	Template base class for implementing mapping on edges.

	\param The first template parameter is the Graph class. The Graph

		must have an \emp edge_maps member with \emp EdgeMapRegistry class.

	\param The second template parameter is the Edge type of the class.

*/

template <typename G, typename K>

class EdgeMapBase {

public:

	typedef G Graph;

	typedef K KeyType;

	/** 

		Default constructor.

	*/	

	EdgeMapBase() : graph(0) {}

	/** 

		Simple constructor to register into a graph.

	*/

	EdgeMapBase(Graph& g) : graph(&g) {

		graph->edge_maps.add(*this);

	}

	/** 

		Copy constructor with registering into the map.

	*/	

	EdgeMapBase(const EdgeMapBase& copy) : graph(copy.graph) {

		if (graph) {

			graph->edge_maps.add(*this);

		}

	} 

	/** 

		Assign operator.

	*/	

	const EdgeMapBase& operator=(const EdgeMapBase& copy) {

		if (graph) {

			graph.edge_maps.erase(*this);

		}

		graph = copy.graph;

		if (graph) {

			graph->edge_maps.add(*this);

		}

	}

	/** 

		Destructor.

	*/	

	virtual ~EdgeMapBase() {

		if (graph) {

			graph.edge_maps.erase(*this);

		}

	}

protected:

	Graph* graph;

	int graph_index;

	/**

		Helper function to implement the default constructor in the subclasses.

	*/

	void init() {

		for (Graph::EdgeIt it(g); g.valid(it); g.next(it)) {

			add(it);

		}

	}

	/**

		Helper function to implement the destructor in the subclasses.

	*/

	void destroy() {

		for (Graph::EdgeIt it(g); g.valid(it); g.next(it)) {

			erase(it);

		}

	}

	/** 

		The add member function should be overloaded in the subclasses.

		\e Add extends the map with the new edge.

	*/

	virtual void add(const KeyType&) = 0;

	/** 

		The erase member function should be overloaded in the subclasses.

		\e Erase removes the edge from the map.

	*/

	virtual void erase(const KeyType&) = 0;

	/**

		Exception class to throw at unsupported operation.

	*/

	class NotSupportedOperationException {};

	friend class Graph;

};

#endif