RhodeCode

      };

      /// The directed arc type.

      /// The directed arc type. It can be converted to the

      /// edge or it should be inherited from the undirected

      public:

        /// Default constructor

        /// @warning The default constructor sets the iterator

        /// to an undefined value.

        Arc() { }

        /// Copy constructor.

        /// Copy constructor.

        ///

        /// Initialize the iterator to be invalid.

        /// Initialize the iterator to be invalid.

        ///

        Arc(Invalid) { }

        /// Equality operator

        ///

        /// \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.

        bool operator<(Arc) const { return false; }

      };

      /// This iterator goes through each directed arc.

      /// This iterator goes through each arc of a graph.

      /// Its usage is quite simple, for example you can count the number

      /// of arcs in a graph \c g of type \c Graph as follows: