// -*- 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