RhodeCode

      /// \brief Constructor for conversion from \c INVALID.

      ///

      /// Constructor for conversion from \c INVALID.

      /// It initializes the item to be invalid.

      /// \sa Invalid for more details.

      GraphItem(Invalid) {}

      /// \brief Assignment operator.

      ///

      /// Assignment operator for the item.

      GraphItem& operator=(const GraphItem&) { return *this; }

      /// \brief Equality operator.

      ///

      /// Equality operator.

      bool operator==(const GraphItem&) const { return false; }

      /// \brief Inequality operator.

      ///

      /// Inequality operator.

      bool operator!=(const GraphItem&) const { return false; }

      /// \brief Ordering operator.

      ///

      /// It makes possible to use graph item types as key types in 

      /// associative containers (e.g. \c std::map).

      ///

      /// \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<(const 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);

          b = (ia == INVALID) && (ib != INVALID);

          b = (ia < ib);

        }

        const _GraphItem &ia;

        ///

        /// Constructor for conversion from \c INVALID.

        /// It initializes the item to be invalid.

        /// \sa Invalid for more details.

        Edge(Invalid) {}

        /// \brief Constructor for conversion from an arc.

        ///

        /// Constructor for conversion from an arc.

        /// Besides the core graph item functionality each arc should

        /// be convertible to the represented edge.

        Edge(const Arc&) {}

      };

      /// \brief Return one end node of an edge.

      ///

      /// This function returns one end node of an edge.

      Node u(const Edge&) const { return INVALID; }

      /// \brief Return the other end node of an edge.

      ///

      /// This function returns the other end node of an edge.

      Node v(const Edge&) const { return INVALID; }

      /// arc id.

      ///

      /// This function returns an integer greater or equal to the

      /// maximum arc id.

      int maxArcId() const { return -1; }

      template <typename _Digraph>

      struct Constraints {

        void constraints() {

          checkConcept<Base, _Digraph >();

          typename _Digraph::Node node;

          int nid = digraph.id(node);

          nid = digraph.id(node);

          node = digraph.nodeFromId(nid);

          typename _Digraph::Arc arc;

          int eid = digraph.id(arc);

          eid = digraph.id(arc);

          arc = digraph.arcFromId(eid);

          nid = digraph.maxNodeId();

          ignore_unused_variable_warning(nid);

          eid = digraph.maxArcId();

          ignore_unused_variable_warning(eid);

        }

        const _Digraph& digraph;

      };