// -*- c++ -*-

#ifndef LEMON_EXTENDABLE_GRAPH_EXTENDER_H

#define LEMON_EXTENDABLE_GRAPH_EXTENDER_H

namespace lemon {

  template <typename _Base> 

  class ExtendableGraphExtender : public _Base {

  public:

    typedef ExtendableGraphExtender Graph;

    typedef _Base Parent;

    typedef typename Parent::Node Node;

    typedef typename Parent::Edge Edge;

    Node addNode() {

      Node node = Parent::addNode();

      Parent::getObserverRegistry(Node()).add(node);

      return node;

    }

    Edge addEdge(const Node& from, const Node& to) {

      Edge edge = Parent::addEdge(from, to);

      Parent::getObserverRegistry(Edge()).add(edge);

      return edge;

    }

  };

}

#endif