diff -r d8475431bbbb -r 8e85e6bbefdf lemon/concept/graph_component.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lemon/concept/graph_component.h	Mon May 23 04:48:14 2005 +0000
@@ -0,0 +1,982 @@
+/* -*- C++ -*-
+ * lemon/concept/graph_component.h - Part of LEMON, a generic C++ optimization library
+ *
+ * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+///\ingroup graph_concepts
+///\file
+///\brief The graph components.
+
+
+#ifndef LEMON_CONCEPT_GRAPH_COMPONENT_H
+#define LEMON_CONCEPT_GRAPH_COMPONENT_H
+
+#include <lemon/invalid.h>
+#include <lemon/concept/maps.h>
+
+#include <lemon/bits/alteration_notifier.h>
+
+namespace lemon {
+  namespace concept {
+
+    /// \addtogroup graph_concepts
+    /// @{
+
+    /****************   Graph iterator concepts   ****************/
+
+    /// Skeleton class for graph Node and Edge types
+
+    /// This class describes the interface of Node and Edge (and UndirEdge
+    /// in undirected graphs) subtypes of graph types.
+    ///
+    /// \note This class is a template class so that we can use it to
+    /// create graph skeleton classes. The reason for this is than Node
+    /// and Edge types should \em not derive from the same base class.
+    /// For Node you should instantiate it with character 'n' and for Edge
+    /// with 'e'.
+
+#ifndef DOXYGEN
+    template <char _selector = '0'>
+#endif
+    class GraphItem {
+    public:
+      /// Default constructor.
+      
+      /// \warning The default constructor is not required to set
+      /// the item to some well-defined value. So you should consider it
+      /// as uninitialized.
+      GraphItem() {}
+      /// Copy constructor.
+      
+      /// Copy constructor.
+      ///
+      GraphItem(GraphItem const&) {}
+      /// Invalid constructor \& conversion.
+
+      /// This constructor initializes the item to be invalid.
+      /// \sa Invalid for more details.
+      GraphItem(Invalid) {}
+      /// Assign operator for nodes.
+
+      /// The nodes are assignable. 
+      ///
+      GraphItem& operator=(GraphItem const&) { return *this; }
+      /// Equality operator.
+      
+      /// Two iterators are equal if and only if they represents the
+      /// same node in the graph or both are invalid.
+      bool operator==(GraphItem) const { return false; }
+      /// Inequality operator.
+	
+      /// \sa operator==(const Node& n)
+      ///
+      bool operator!=(GraphItem) const { return false; }
+
+      /// Artificial ordering operator.
+
+      /// To allow the use of graph descriptors as key type in std::map or
+      /// similar associative container we require this.
+      ///
+      /// \note This operator only have to define some strict ordering of
+      /// the items; this order has nothing to do with the iteration
+      /// ordering of the items.
+      ///
+      /// \bug This is a technical requirement. Do we really need this?
+      bool operator<(GraphItem) const { return false; }
+
+      template<typename _GraphItem>
+      struct Constraints {
+	void constraints() {
+	  _GraphItem i1;
+	  _GraphItem i2 = i1;
+	  _GraphItem i3 = INVALID;
+	  
+	  i1 = i2 = i3;
+
+	  bool b;
+	  //	  b = (ia == ib) && (ia != ib) && (ia < ib);
+	  b = (ia == ib) && (ia != ib);
+	  b = (ia == INVALID) && (ib != INVALID);
+	  //	  b = (ia < ib);
+	}
+
+	const _GraphItem &ia;
+	const _GraphItem &ib;
+      };
+    };
+
+    /// A type describing the concept of graph node
+
+    /// This is an instantiation of \ref GraphItem which can be used as a
+    /// Node subtype in graph skeleton definitions
+    typedef GraphItem<'n'> GraphNode;
+
+    /// A type describing the concept of graph edge
+
+    /// This is an instantiation of \ref GraphItem which can be used as a
+    /// Edge subtype in graph skeleton definitions
+    typedef GraphItem<'e'> GraphEdge;
+
+
+    /**************** Basic features of graphs ****************/
+
+    /// An empty base graph class.
+  
+    /// This class provides the minimal set of features needed for a graph
+    /// structure. All graph concepts have to be conform to this base
+    /// graph.
+    ///
+    /// \bug This is not true. The minimal graph concept is the
+    /// BaseIterableGraphComponent.
+
+    class BaseGraphComponent {
+    public:
+
+      typedef BaseGraphComponent Graph;
+      
+      /// Node class of the graph.
+
+      /// This class represents the Nodes of the graph. 
+      ///
+      typedef GraphItem<'n'> Node;
+
+      /// Edge class of the graph.
+
+      /// This class represents the Edges of the graph. 
+      ///
+      typedef GraphItem<'e'> Edge;
+
+      ///Gives back the target node of an edge.
+
+      ///Gives back the target node of an edge.
+      ///
+      Node target(const Edge&) const { return INVALID;}
+
+      ///Gives back the source node of an edge.
+
+      ///Gives back the source node of an edge.
+      ///
+      Node source(const Edge&) const { return INVALID;}
+
+
+      template <typename _Graph>
+      struct Constraints {
+	typedef typename _Graph::Node Node;
+	typedef typename _Graph::Edge Edge;
+      
+	void constraints() {
+	  checkConcept<GraphItem<'n'>, Node>();
+	  checkConcept<GraphItem<'e'>, Edge>();
+	  {
+	    Node n;
+	    Edge e;
+	    n = graph.source(e);
+	    n = graph.target(e);
+	  }      
+	}
+      
+	const _Graph& graph;
+      };
+    };
+
+    /// An empty iterable base graph class.
+  
+    /// This class provides beside the core graph features
+    /// core iterable interface for the graph structure.
+    /// Most of the base graphs should be conform to this concept.
+
+    class BaseIterableGraphComponent : virtual public BaseGraphComponent {
+    public:
+
+      typedef BaseGraphComponent::Node Node;
+      typedef BaseGraphComponent::Edge Edge;
+
+      /// Gives back the first Node in the iterating order.
+      
+      /// Gives back the first Node in the iterating order.
+      ///     
+      void first(Node&) const {}
+
+      /// Gives back the next Node in the iterating order.
+      
+      /// Gives back the next Node in the iterating order.
+      ///     
+      void next(Node&) const {}
+
+      /// Gives back the first Edge in the iterating order.
+      
+      /// Gives back the first Edge in the iterating order.
+      ///     
+      void first(Edge&) const {}
+      /// Gives back the next Edge in the iterating order.
+      
+      /// Gives back the next Edge in the iterating order.
+      ///     
+      void next(Edge&) const {}
+
+
+      /// Gives back the first of the Edges point to the given Node.
+      
+      /// Gives back the first of the Edges point to the given Node.
+      ///     
+      void firstIn(Edge&, const Node&) const {}
+
+      /// Gives back the next of the Edges points to the given Node.
+
+
+      /// Gives back the next of the Edges points to the given Node.
+      ///
+      void nextIn(Edge&) const {}
+
+      /// Gives back the first of the Edges start from the given Node.
+      
+      /// Gives back the first of the Edges start from the given Node.
+      ///     
+      void firstOut(Edge&, const Node&) const {}
+
+      /// Gives back the next of the Edges start from the given Node.
+      
+      /// Gives back the next of the Edges start from the given Node.
+      ///     
+      void nextOut(Edge&) const {}
+
+
+      template <typename _Graph>
+      struct Constraints {
+      
+	void constraints() {
+	  checkConcept< BaseGraphComponent, _Graph >();
+	  typename _Graph::Node node;      
+	  typename _Graph::Edge edge;
+	  {
+	    graph.first(node);
+	    graph.next(node);
+	  }
+	  {
+	    graph.first(edge);
+	    graph.next(edge);
+	  }
+	  {
+	    graph.firstIn(edge, node);
+	    graph.nextIn(edge);
+	  }
+	  {
+	    graph.firstOut(edge, node);
+	    graph.nextOut(edge);
+	  }
+	}
+
+	const _Graph& graph;
+      };
+    };
+
+    /// An empty idable base graph class.
+  
+    /// This class provides beside the core graph features
+    /// core id functions for the graph structure.
+    /// The most of the base graphs should be conform to this concept.
+    /// The id's are unique and immutable.
+    class IDableGraphComponent : virtual public BaseGraphComponent {
+    public:
+
+      typedef BaseGraphComponent::Node Node;
+      typedef BaseGraphComponent::Edge Edge;
+
+      /// Gives back an unique integer id for the Node. 
+
+      /// Gives back an unique integer id for the Node. 
+      ///
+      int id(const Node&) const { return -1;}
+
+      /// \brief Gives back the node by the unique id.
+      ///
+      /// Gives back the node by the unique id.
+      /// If the graph does not contain node with the given id
+      /// then the result of the function is undetermined. 
+      Node fromId(int , Node) const { return INVALID;}
+
+      /// \brief Gives back an unique integer id for the Edge. 
+      ///
+      /// Gives back an unique integer id for the Edge. 
+      ///
+      int id(const Edge&) const { return -1;}
+
+      /// \brief Gives back the edge by the unique id.
+      ///
+      /// Gives back the edge by the unique id.
+      /// If the graph does not contain edge with the given id
+      /// then the result of the function is undetermined. 
+      Edge fromId(int, Edge) const { return INVALID;}
+
+      template <typename _Graph>
+      struct Constraints {
+
+	void constraints() {
+	  checkConcept< BaseGraphComponent, _Graph >();
+	  typename _Graph::Node node;
+	  int nid = graph.id(node);
+	  nid = graph.id(node);
+	  node = graph.fromId(nid, Node());
+	  typename _Graph::Edge edge;
+	  int eid = graph.id(edge);
+	  eid = graph.id(edge);
+	  edge = graph.fromId(eid, Edge());
+	}
+
+	const _Graph& graph;
+      };
+    };
+
+
+    /// An empty max-idable base graph class.
+  
+    /// This class provides beside the core graph features
+    /// core max id functions for the graph structure.
+    /// The most of the base graphs should be conform to this concept.
+    /// The id's are unique and immutable.
+    class MaxIDableGraphComponent : virtual public BaseGraphComponent {
+    public:
+
+      /// Gives back an integer greater or equal to the maximum Node id. 
+
+      /// Gives back an integer greater or equal to the maximum Node id. 
+      ///
+      int maxId(Node = INVALID) const { return -1;}
+
+      /// Gives back an integer greater or equal to the maximum Edge id. 
+
+      /// Gives back an integer greater or equal to the maximum Edge id. 
+      ///
+      int maxId(Edge = INVALID) const { return -1;}
+
+      template <typename _Graph>
+      struct Constraints {
+
+	void constraints() {
+	  checkConcept<BaseGraphComponent, _Graph>();
+	  int nid = graph.maxId(typename _Graph::Node());
+	  ignore_unused_variable_warning(nid);
+	  int eid = graph.maxId(typename _Graph::Edge());
+	  ignore_unused_variable_warning(eid);
+	}
+      
+	const _Graph& graph;
+      };
+    };
+
+    /// An empty extendable base graph class.
+  
+    /// This class provides beside the core graph features
+    /// core graph extend interface for the graph structure.
+    /// The most of the base graphs should be conform to this concept.
+    class BaseExtendableGraphComponent : virtual public BaseGraphComponent {
+    public:
+
+      typedef BaseGraphComponent::Node Node;
+      typedef BaseGraphComponent::Edge Edge;
+
+      /// Adds a new Node to the graph.
+
+      /// Adds a new Node to the graph.
+      ///
+      Node addNode() {
+	return INVALID;
+      }
+    
+      /// Adds a new Edge connects the two Nodes to the graph.
+
+      /// Adds a new Edge connects the two Nodes to the graph.
+      ///
+      Edge addEdge(const Node&, const Node&) {
+	return INVALID;
+      }
+
+      template <typename _Graph>
+      struct Constraints {
+	void constraints() {
+	  checkConcept<BaseGraphComponent, _Graph >();
+	  typename _Graph::Node node_a, node_b;
+	  node_a = graph.addNode();
+	  typename _Graph::Edge edge;
+	  edge = graph.addEdge(node_a, node_b);
+	}
+
+	_Graph& graph;
+      };
+    };
+
+    /// An empty erasable base graph class.
+  
+    /// This class provides beside the core graph features
+    /// core erase functions for the graph structure.
+    /// The most of the base graphs should be conform to this concept.
+    class BaseErasableGraphComponent : virtual public BaseGraphComponent {
+    public:
+
+      typedef BaseGraphComponent::Node Node;
+      typedef BaseGraphComponent::Edge Edge;
+
+      /// Erase a Node from the graph.
+      
+      /// Erase a Node from the graph. This function should not
+      /// erase edges connecting to the Node.
+      void erase(const Node&) {}    
+
+      /// Erase an Edge from the graph.
+
+      /// Erase an Edge from the graph.
+      ///
+      void erase(const Edge&) {}
+
+      template <typename _Graph>
+      struct Constraints {
+	void constraints() {
+	  checkConcept<BaseGraphComponent, _Graph>();
+	  typename _Graph::Node node;
+	  graph.erase(node);
+	  typename _Graph::Edge edge;
+	  graph.erase(edge);
+	}
+
+	_Graph& graph;
+      };
+    };
+
+    /// An empty clearable base graph class.
+  
+    /// This class provides beside the core graph features
+    /// core clear functions for the graph structure.
+    /// The most of the base graphs should be conform to this concept.
+    class ClearableGraphComponent : virtual public BaseGraphComponent {
+    public:
+
+      /// Erase all the Nodes and Edges from the graph.
+
+      /// Erase all the Nodes and Edges from the graph.
+      ///
+      void clear() {}    
+
+      template <typename _Graph>
+      struct Constraints {
+	void constraints() {
+	  checkConcept<BaseGraphComponent, _Graph>();
+	  graph.clear();
+	}
+
+	_Graph graph;
+      };
+    };
+
+
+    /// Skeleton class for graph NodeIt and EdgeIt
+
+    /// Skeleton class for graph NodeIt and EdgeIt.
+    ///
+    template <typename _Graph, typename _Item>
+    class GraphIterator : public _Item {
+    public:
+      /// \todo Don't we need the Item type as typedef?
+
+      /// Default constructor.
+      
+      /// @warning The default constructor sets the iterator
+      /// to an undefined value.
+      GraphIterator() {}
+      /// Copy constructor.
+      
+      /// Copy constructor.
+      ///
+      GraphIterator(GraphIterator const&) {}
+      /// Sets the iterator to the first item.
+      
+      /// Sets the iterator to the first item of \c the graph.
+      ///
+      explicit GraphIterator(const _Graph&) {}
+      /// Invalid constructor \& conversion.
+
+      /// This constructor initializes the item to be invalid.
+      /// \sa Invalid for more details.
+      GraphIterator(Invalid) {}
+      /// Assign operator for items.
+
+      /// The items are assignable. 
+      ///
+      GraphIterator& operator=(GraphIterator const&) { return *this; }      
+      /// Next item.
+
+      /// Assign the iterator to the next item.
+      ///
+      GraphIterator& operator++() { return *this; }
+      //	Node operator*() const { return INVALID; }
+      /// Equality operator
+
+      /// Two iterators are equal if and only if they point to the
+      /// same object or both are invalid.
+      bool operator==(const GraphIterator&) const { return true;}
+      /// Inequality operator
+	
+      /// \sa operator==(Node n)
+      ///
+      bool operator!=(const GraphIterator&) const { return true;}
+      
+      template<typename _GraphIterator>
+      struct Constraints {
+	void constraints() {
+	  //	  checkConcept< Item, _GraphIterator >();
+	  _GraphIterator it1(g);
+	
+	  /// \todo Do we need NodeIt(Node) kind of constructor?
+	  //	_GraphIterator it2(bj);
+	  _GraphIterator it2;
+
+	  it2 = ++it1;
+	  ++it2 = it1;
+	  ++(++it1);
+	  /// \bug This should be: is_base_and_derived<BaseItem, _GraphIterator>
+	  _Item bi = it1;
+	  bi = it2;
+	}
+	_Graph& g;
+      };
+    };
+
+    /// Skeleton class for graph InEdgeIt and OutEdgeIt
+
+    /// \note Because InEdgeIt and OutEdgeIt may not inherit from the same
+    /// base class, the _selector is a additional template parameter. For 
+    /// InEdgeIt you should instantiate it with character 'i' and for 
+    /// OutEdgeIt with 'o'.
+    /// \todo Is this a good name for this concept?
+    template <typename Graph,
+	      typename Edge = typename Graph::Edge,
+	      char _selector = '0'>
+    class GraphIncIterator : public Edge {
+    public:
+      /// Default constructor.
+      
+      /// @warning The default constructor sets the iterator
+      /// to an undefined value.
+      GraphIncIterator() {}
+      /// Copy constructor.
+      
+      /// Copy constructor.
+      ///
+      GraphIncIterator(GraphIncIterator const& gi) :Edge(gi) {}
+      /// Sets the iterator to the first edge incoming into or outgoing 
+      /// from the node.
+      
+      /// Sets the iterator to the first edge incoming into or outgoing 
+      /// from the node.
+      ///
+      explicit GraphIncIterator(const Graph&, const typename Graph::Node&) {}
+      /// Invalid constructor \& conversion.
+
+      /// This constructor initializes the item to be invalid.
+      /// \sa Invalid for more details.
+      GraphIncIterator(Invalid) {}
+      /// Assign operator for nodes.
+
+      /// The nodes are assignable. 
+      ///
+      GraphIncIterator& operator=(GraphIncIterator const&) { return *this; }      
+      /// Next edge.
+
+      /// Assign the iterator to the next node.
+      ///
+      GraphIncIterator& operator++() { return *this; }
+
+      //	Node operator*() const { return INVALID; }
+
+      /// Equality operator
+
+      /// Two iterators are equal if and only if they point to the
+      /// same object or both are invalid.
+      bool operator==(const GraphIncIterator&) const { return true;}
+
+      /// Inequality operator
+	
+      /// \sa operator==(Node n)
+      ///
+      bool operator!=(const GraphIncIterator&) const { return true;}
+
+      template <typename _GraphIncIterator>
+      struct Constraints {
+	typedef typename Graph::Node Node;
+	void constraints() {
+	  checkConcept<GraphItem<'e'>, _GraphIncIterator>();
+	  _GraphIncIterator it1(graph, node);
+	  /// \todo Do we need OutEdgeIt(Edge) kind of constructor?
+	  //	_GraphIncIterator it2(edge);
+	  _GraphIncIterator it2;
+
+	  it2 = ++it1;
+	  ++it2 = it1;
+	  ++(++it1);
+	  Edge e = it1;
+	  e = it2;
+
+	  const_constraits();
+	}
+
+	void const_constraits() {
+	  Node n = graph.baseNode(it);
+	  n = graph.runningNode(it);
+	}
+
+	Edge edge;
+	Node node;
+	Graph graph;
+	_GraphIncIterator it;
+      };
+    };
+
+
+    /// An empty iterable base graph class.
+  
+    /// This class provides beside the core graph features
+    /// iterator based iterable interface for the graph structure.
+    /// This concept is part of the StaticGraphConcept.
+    class IterableGraphComponent : virtual public BaseGraphComponent {
+
+    public:
+    
+      typedef IterableGraphComponent Graph;
+
+      typedef BaseGraphComponent::Node Node;
+      typedef BaseGraphComponent::Edge Edge;
+
+      /// This iterator goes through each node.
+
+      /// This iterator goes through each node.
+      ///
+      typedef GraphIterator<Graph, Node> NodeIt;
+      /// This iterator goes through each node.
+
+      /// This iterator goes through each node.
+      ///
+      typedef GraphIterator<Graph, Edge> EdgeIt;
+      /// This iterator goes trough the incoming edges of a node.
+
+      /// This iterator goes trough the \e inccoming edges of a certain node
+      /// of a graph.
+      typedef GraphIncIterator<Graph, Edge, 'i'> InEdgeIt;
+      /// This iterator goes trough the outgoing edges of a node.
+
+      /// This iterator goes trough the \e outgoing edges of a certain node
+      /// of a graph.
+      typedef GraphIncIterator<Graph, Edge, 'o'> OutEdgeIt;
+    };
+    
+    template <typename _Graph> 
+    struct Constraints {
+      void constraints() {
+  	checkConcept< BaseGraphComponent, _Graph>();
+
+	checkConcept<GraphIterator<_Graph, typename _Graph::Edge>,
+	  typename _Graph::EdgeIt >();
+	checkConcept<GraphIterator<_Graph, typename _Graph::Node>,
+	  typename _Graph::NodeIt >();
+	checkConcept<GraphIncIterator<_Graph>, typename _Graph::InEdgeIt >();
+	checkConcept<GraphIncIterator<_Graph>, typename _Graph::OutEdgeIt >();
+      }
+    };
+
+    /// An empty alteration notifier base graph class.
+  
+    /// This class provides beside the core graph features
+    /// alteration notifier interface for the graph structure.
+    /// This is an observer-notifier pattern. More Obsevers can
+    /// be registered into the notifier and whenever an alteration
+    /// occured in the graph all the observers will notified about it.
+    class AlterableGraphComponent : virtual public BaseGraphComponent {
+    public:
+
+      /// The edge observer registry.
+      typedef AlterationNotifier<Edge> EdgeNotifier;
+      /// The node observer registry.
+      typedef AlterationNotifier<Node> NodeNotifier;
+      
+      /// \brief Gives back the edge alteration notifier.
+      ///
+      /// Gives back the edge alteration notifier.
+      EdgeNotifier getNotifier(Edge) const {
+	return EdgeNotifier();
+      }
+      
+      /// \brief Gives back the node alteration notifier.
+      ///
+      /// Gives back the node alteration notifier.
+      NodeNotifier getNotifier(Node) const {
+	return NodeNotifier();
+      }
+      
+    };
+
+
+    /// Class describing the concept of graph maps
+
+    /// This class describes the common interface of the graph maps
+    /// (NodeMap, EdgeMap), that is \ref maps-pages "maps" which can be used to
+    /// associate data to graph descriptors (nodes or edges).
+    template <typename Graph, typename Item, typename _Value>
+    class GraphMap : public ReadWriteMap<Item, _Value> {
+    protected:      
+      GraphMap() {}
+    public:
+      /// \brief Construct a new map.
+      ///
+      /// Construct a new map for the graph.
+      explicit GraphMap(const Graph&) {}
+      /// \brief Construct a new map with default value.
+      ///
+      /// Construct a new map for the graph and initalise the values.
+      GraphMap(const Graph&, const _Value&) {}
+      /// \brief Copy constructor.
+      ///
+      /// Copy Constructor.
+      GraphMap(const GraphMap& gm) :ReadWriteMap<Item, _Value>(gm) {}
+      
+      /// \brief Assign operator.
+      ///
+      /// Assign operator.
+      GraphMap& operator=(const GraphMap&) { return *this;}
+
+      template<typename _Map>
+      struct Constraints {
+	void constraints() {
+	  checkConcept<ReadWriteMap<Item, _Value>, _Map >();
+	  // Construction with a graph parameter
+	  _Map a(g);
+	  // Constructor with a graph and a default value parameter
+	  _Map a2(g,t);
+	  // Copy constructor. Do we need it?
+	  _Map b=c;
+	  // Copy operator. Do we need it?
+	  a=b;
+
+	  ignore_unused_variable_warning(a2);
+	}
+
+	const _Map &c;
+	const Graph &g;
+	const typename GraphMap::Value &t;
+      };
+
+    };
+
+    /// An empty mappable base graph class.
+  
+    /// This class provides beside the core graph features
+    /// map interface for the graph structure.
+    /// This concept is part of the StaticGraphConcept.
+    class MappableGraphComponent : virtual public BaseGraphComponent {
+    public:
+
+      typedef MappableGraphComponent Graph;
+
+      typedef BaseGraphComponent::Node Node;
+      typedef BaseGraphComponent::Edge Edge;
+
+      /// ReadWrite map of the nodes.
+    
+      /// ReadWrite map of the nodes.
+      ///
+      template <typename _Value>
+      class NodeMap : public GraphMap<Graph, Node, _Value> {
+      private:
+	NodeMap();
+      public:
+	/// \brief Construct a new map.
+	///
+	/// Construct a new map for the graph.
+	/// \todo call the right parent class constructor
+	explicit NodeMap(const Graph&) {}
+	/// \brief Construct a new map with default value.
+	///
+	/// Construct a new map for the graph and initalise the values.
+	NodeMap(const Graph&, const _Value&) {}
+	/// \brief Copy constructor.
+	///
+	/// Copy Constructor.
+	NodeMap(const NodeMap& nm) : GraphMap<Graph, Node, _Value>(nm) {}
+
+	/// \brief Assign operator.
+	///
+	/// Assign operator.
+	NodeMap& operator=(const NodeMap&) { return *this;}
+
+      };
+
+      /// ReadWrite map of the edges.
+    
+      /// ReadWrite map of the edges.
+      ///
+      template <typename _Value>
+      class EdgeMap : public GraphMap<Graph, Edge, _Value> {
+      private:
+	EdgeMap();
+      public:
+	/// \brief Construct a new map.
+	///
+	/// Construct a new map for the graph.
+	/// \todo call the right parent class constructor
+	explicit EdgeMap(const Graph&) {}
+	/// \brief Construct a new map with default value.
+	///
+	/// Construct a new map for the graph and initalise the values.
+	EdgeMap(const Graph&, const _Value&) {}
+	/// \brief Copy constructor.
+	///
+	/// Copy Constructor.
+	EdgeMap(const EdgeMap& em) :GraphMap<Graph, Edge, _Value>(em) {}
+
+	/// \brief Assign operator.
+	///
+	/// Assign operator.
+	EdgeMap& operator=(const EdgeMap&) { return *this;}
+
+      };
+
+      template <typename _Graph>
+      struct Constraints {
+
+	struct Type {
+	  int value;
+	  Type() : value(0) {}
+	  Type(int _v) : value(_v) {}
+	};
+
+	void constraints() {
+	  checkConcept<BaseGraphComponent, _Graph>();
+	  { // int map test
+	    typedef typename _Graph::template NodeMap<int> IntNodeMap;
+	    checkConcept<GraphMap<_Graph, typename _Graph::Node, int>, 
+	      IntNodeMap >();
+	  } { // bool map test
+	    typedef typename _Graph::template NodeMap<bool> BoolNodeMap;
+	    checkConcept<GraphMap<_Graph, typename _Graph::Node, bool>,
+	      BoolNodeMap >();
+	  } { // Type map test
+	    typedef typename _Graph::template NodeMap<Type> TypeNodeMap;
+	    checkConcept<GraphMap<_Graph, typename _Graph::Node, Type>,
+	      TypeNodeMap >();
+	  } 
+
+	  { // int map test
+	    typedef typename _Graph::template EdgeMap<int> IntEdgeMap;
+	    checkConcept<GraphMap<_Graph, typename _Graph::Edge, int>,
+	      IntEdgeMap >();
+	  } { // bool map test
+	    typedef typename _Graph::template EdgeMap<bool> BoolEdgeMap;
+	    checkConcept<GraphMap<_Graph, typename _Graph::Edge, bool>,
+	      BoolEdgeMap >();
+	  } { // Type map test
+	    typedef typename _Graph::template EdgeMap<Type> TypeEdgeMap;
+	    checkConcept<GraphMap<_Graph, typename _Graph::Edge, Type>, 
+	      TypeEdgeMap >();
+	  } 
+	}
+
+	_Graph& graph;
+      };
+    };
+
+    /// \brief An empty extendable extended graph class.
+    ///
+    /// This class provides beside the core graph features
+    /// item addition interface for the graph structure.
+    /// The difference between this class and the 
+    /// \c BaseExtendableGraphComponent is that it should
+    /// notify the item alteration observers.
+    class ExtendableGraphComponent : virtual public BaseGraphComponent {
+    public:
+
+      typedef ExtendableGraphComponent Graph;
+
+      typedef BaseGraphComponent::Node Node;
+      typedef BaseGraphComponent::Edge Edge;
+
+      /// \brief Add a node to the graph.
+      ///
+      /// Add a node to the graph and notify the observers.
+      Node addNode() {
+	return INVALID;
+      }
+    
+      /// \brief Add an edge to the graph.
+      ///
+      /// Add an edge to the graph and notify the observers.
+      Edge addEdge(const Node&, const Node&) {
+	return INVALID;
+      }
+
+      template <typename _Graph>
+      struct Constraints {
+	void constraints() {
+	  checkConcept<BaseGraphComponent, _Graph >();
+	  typename _Graph::Node node_a, node_b;
+	  node_a = graph.addNode();
+	  typename _Graph::Edge edge;
+	  edge = graph.addEdge(node_a, node_b);      
+	}
+	_Graph& graph;
+      };
+    };
+
+    /// \brief An empty erasable extended graph class.
+    ///
+    /// This class provides beside the core graph features
+    /// item erase interface for the graph structure.
+    /// The difference between this class and the 
+    /// \c BaseErasableGraphComponent is that it should
+    /// notify the item alteration observers.
+    class ErasableGraphComponent : virtual public BaseGraphComponent {
+    public:
+
+      typedef ErasableGraphComponent Graph;
+
+      typedef BaseGraphComponent::Node Node;
+      typedef BaseGraphComponent::Edge Edge;
+
+      /// \brief Erase the Node and notify the node alteration observers.
+      ///
+      ///  Erase the Node and notify the node alteration observers.
+      void erase(const Node&) {}    
+
+      /// \brief Erase the Edge and notify the edge alteration observers.
+      ///
+      ///  Erase the Edge and notify the edge alteration observers.
+      void erase(const Edge&) {}
+
+      template <typename _Graph>
+      struct Constraints {
+	void constraints() {
+	  checkConcept<BaseGraphComponent, _Graph >();
+	  typename _Graph::Node node;
+	  graph.erase(node);
+	  typename _Graph::Edge edge;
+	  graph.erase(edge);      
+	}
+
+	_Graph& graph;
+      };
+    };
+
+    /// @}
+
+  }
+
+}
+
+#endif