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/*===========================================================================*\
 *                                                                           *             
 *   $Revision: 1258 $                                                         *
 *   $Date: 2015-04-28 15:07:46 +0200 (Di, 28 Apr 2015) $                   *
 *                                                                           *
\*===========================================================================*/

#ifndef OPENMESH_CIRCULATORS_HH
#define OPENMESH_CIRCULATORS_HH
//=============================================================================
//
//  Vertex and Face circulators for PolyMesh/TriMesh
//
//=============================================================================



//== INCLUDES =================================================================

#include <OpenMesh/Core/System/config.h>
#include <cassert>
#include <cstddef>
#include <iterator>

//== NAMESPACES ===============================================================

namespace OpenMesh {
namespace Iterators {

template<class Mesh, class CenterEntityHandle, bool CW>
class GenericCirculator_CenterEntityFnsT {
    public:
        static void increment(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter);
        static void decrement(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter);
};

template<class Mesh>
class GenericCirculator_CenterEntityFnsT<Mesh, typename Mesh::VertexHandle, true> {
    public:
        inline static void increment(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            heh = mesh->cw_rotated_halfedge_handle(heh);
            if (heh == start) ++lap_counter;
        }
        inline static void decrement(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            if (heh == start) --lap_counter;
            heh = mesh->ccw_rotated_halfedge_handle(heh);
        }
};

template<class Mesh>
class GenericCirculator_CenterEntityFnsT<Mesh, typename Mesh::FaceHandle, true> {
    public:
        inline static void increment(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            heh = mesh->next_halfedge_handle(heh);
            if (heh == start) ++lap_counter;
        }
        inline static void decrement(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            if (heh == start) --lap_counter;
            heh = mesh->prev_halfedge_handle(heh);
        }
};

/////////////////////////////////////////////////////////////
// CCW

template<class Mesh>
class GenericCirculator_CenterEntityFnsT<Mesh, typename Mesh::VertexHandle, false> {
    public:
        inline static void increment(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            heh = mesh->ccw_rotated_halfedge_handle(heh);
            if (heh == start) ++lap_counter;
        }
        inline static void decrement(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            if (heh == start) --lap_counter;
            heh = mesh->cw_rotated_halfedge_handle(heh);
        }
};

template<class Mesh>
class GenericCirculator_CenterEntityFnsT<Mesh, typename Mesh::FaceHandle, false>  {
    public:
        inline static void increment(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            heh = mesh->prev_halfedge_handle(heh);
            if (heh == start) ++lap_counter;
        }
        inline static void decrement(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            if (heh == start) --lap_counter;
            heh = mesh->next_halfedge_handle(heh);
        }
};
/////////////////////////////////////////////////////////////

template<class Mesh, class CenterEntityHandle, class ValueHandle>
class GenericCirculator_DereferenciabilityCheckT {
    public:
        //inline static bool isDereferenciable(const Mesh *mesh, const typename Mesh::HalfedgeHandle &heh, const typename Mesh::HalfedgeHandle &start, const int &lap_counter);
};

template<class Mesh>
class GenericCirculator_DereferenciabilityCheckT<Mesh, typename Mesh::FaceHandle, typename Mesh::FaceHandle> {
    public:
        inline static bool isDereferenciable(const Mesh *mesh, const typename Mesh::HalfedgeHandle &heh) {
            return mesh->face_handle(mesh->opposite_halfedge_handle(heh)).is_valid();
        }
};

template<class Mesh>
class GenericCirculator_DereferenciabilityCheckT<Mesh, typename Mesh::VertexHandle, typename Mesh::FaceHandle> {
    public:
        inline static bool isDereferenciable(const Mesh *mesh, const typename Mesh::HalfedgeHandle &heh) {
            return mesh->face_handle(heh).is_valid();
        }
};

template<class Mesh, class CenterEntityHandle, class ValueHandle, bool CW = true>
class GenericCirculator_ValueHandleFnsT {
    public:
        inline static bool is_valid(const typename Mesh::HalfedgeHandle &heh, const int lap_counter) {
            return ( heh.is_valid() && (lap_counter == 0 ) );
        }
        inline static void init(const Mesh*, typename Mesh::HalfedgeHandle&, typename Mesh::HalfedgeHandle&, int&) {};
        inline static void increment(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            GenericCirculator_CenterEntityFnsT<Mesh, CenterEntityHandle, CW>::increment(mesh, heh, start, lap_counter);
        }
        inline static void decrement(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            GenericCirculator_CenterEntityFnsT<Mesh, CenterEntityHandle, CW>::decrement(mesh, heh, start, lap_counter);
        }
};

template<class Mesh, class CenterEntityHandle, bool CW>
class GenericCirculator_ValueHandleFnsT<Mesh, CenterEntityHandle, typename Mesh::FaceHandle, CW> {
    public:
        typedef GenericCirculator_DereferenciabilityCheckT<Mesh, CenterEntityHandle, typename Mesh::FaceHandle> GenericCirculator_DereferenciabilityCheck;

        inline static bool is_valid(const typename Mesh::HalfedgeHandle &heh, const int lap_counter) {
            return ( heh.is_valid() &&  (lap_counter == 0));
        }
        inline static void init(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            if (heh.is_valid() && !GenericCirculator_DereferenciabilityCheck::isDereferenciable(mesh, heh) && lap_counter == 0 )
                increment(mesh, heh, start, lap_counter);
        };
        inline static void increment(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            do {
                GenericCirculator_CenterEntityFnsT<Mesh, CenterEntityHandle, CW>::increment(mesh, heh, start, lap_counter);
            } while (is_valid(heh, lap_counter) && !GenericCirculator_DereferenciabilityCheck::isDereferenciable(mesh, heh));
        }
        inline static void decrement(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            do {
                GenericCirculator_CenterEntityFnsT<Mesh, CenterEntityHandle, CW>::decrement(mesh, heh, start, lap_counter);
            } while (is_valid(heh, lap_counter) && !GenericCirculator_DereferenciabilityCheck::isDereferenciable(mesh, heh));
        }
};

template<class Mesh>
class GenericCirculatorBaseT {
    public:
        typedef const Mesh* mesh_ptr;
        typedef const Mesh& mesh_ref;

    public:
        GenericCirculatorBaseT() : mesh_(0), lap_counter_(0) {}

        GenericCirculatorBaseT(mesh_ref mesh, HalfedgeHandle heh, bool end = false) :
            mesh_(&mesh), start_(heh), heh_(heh), lap_counter_(static_cast<int>(end)) {}

        GenericCirculatorBaseT(const GenericCirculatorBaseT &rhs) :
            mesh_(rhs.mesh_), start_(rhs.start_), heh_(rhs.heh_), lap_counter_(rhs.lap_counter_) {}

        inline typename Mesh::FaceHandle toFaceHandle() const {
            return mesh_->face_handle(heh_);
        }

        inline typename Mesh::FaceHandle toOppositeFaceHandle() const {
            return mesh_->face_handle(toOppositeHalfedgeHandle());
        }

        inline typename Mesh::EdgeHandle toEdgeHandle() const {
            return mesh_->edge_handle(heh_);
        }

        inline typename Mesh::HalfedgeHandle toHalfedgeHandle() const {
            return heh_;
        }

        inline typename Mesh::HalfedgeHandle toOppositeHalfedgeHandle() const {
            return mesh_->opposite_halfedge_handle(heh_);
        }

        inline typename Mesh::VertexHandle toVertexHandle() const {
            return mesh_->to_vertex_handle(heh_);
        }

        inline GenericCirculatorBaseT &operator=(const GenericCirculatorBaseT &rhs) {
            mesh_ = rhs.mesh_;
            start_ = rhs.start_;
            heh_ = rhs.heh_;
            lap_counter_ = rhs.lap_counter_;
            return *this;
        }

        inline bool operator==(const GenericCirculatorBaseT &rhs) const {
            return mesh_ == rhs.mesh_ && start_ == rhs.start_ && heh_ == rhs.heh_ && lap_counter_ == rhs.lap_counter_;
        }

        inline bool operator!=(const GenericCirculatorBaseT &rhs) const {
            return !operator==(rhs);
        }

    protected:
        mesh_ptr mesh_;
        typename Mesh::HalfedgeHandle start_, heh_;
        int lap_counter_;
};

template<class Mesh, class CenterEntityHandle, class ValueHandle,
        ValueHandle (GenericCirculatorBaseT<Mesh>::*Handle2Value)() const, bool CW = true >
class GenericCirculatorT : protected GenericCirculatorBaseT<Mesh> {
    public:
        typedef std::ptrdiff_t difference_type;
        typedef ValueHandle value_type;
        typedef const value_type& reference;
        typedef const value_type* pointer;
        typedef std::bidirectional_iterator_tag iterator_category;

        typedef typename GenericCirculatorBaseT<Mesh>::mesh_ptr mesh_ptr;
        typedef typename GenericCirculatorBaseT<Mesh>::mesh_ref mesh_ref;
        typedef GenericCirculator_ValueHandleFnsT<Mesh, CenterEntityHandle, ValueHandle, CW> GenericCirculator_ValueHandleFns;

    public:
        GenericCirculatorT() {}
        GenericCirculatorT(mesh_ref mesh, CenterEntityHandle start, bool end = false) :
            GenericCirculatorBaseT<Mesh>(mesh, mesh.halfedge_handle(start), end) {

            GenericCirculator_ValueHandleFns::init(this->mesh_, this->heh_, this->start_, this->lap_counter_);
        }
        GenericCirculatorT(mesh_ref mesh, HalfedgeHandle heh, bool end = false) :
            GenericCirculatorBaseT<Mesh>(mesh, heh, end) {

            GenericCirculator_ValueHandleFns::init(this->mesh_, this->heh_, this->start_, this->lap_counter_);
        }
        GenericCirculatorT(const GenericCirculatorT &rhs) : GenericCirculatorBaseT<Mesh>(rhs) {}

        friend class GenericCirculatorT<Mesh,CenterEntityHandle,ValueHandle,Handle2Value,!CW>;
        explicit GenericCirculatorT( const GenericCirculatorT<Mesh,CenterEntityHandle,ValueHandle,Handle2Value,!CW>& rhs )
        :GenericCirculatorBaseT<Mesh>(rhs){}

        GenericCirculatorT& operator++() {
            assert(this->mesh_);
            GenericCirculator_ValueHandleFns::increment(this->mesh_, this->heh_, this->start_, this->lap_counter_);
            return *this;
        }
        GenericCirculatorT& operator--() {
            assert(this->mesh_);
            GenericCirculator_ValueHandleFns::decrement(this->mesh_, this->heh_, this->start_, this->lap_counter_);
            return *this;
        }

        /// Post-increment
        GenericCirculatorT operator++(int) {
            assert(this->mesh_);
            GenericCirculatorT cpy(*this);
            ++(*this);
            return cpy;
        }

        /// Post-decrement
        GenericCirculatorT operator--(int) {
            assert(this->mesh_);
            GenericCirculatorT cpy(*this);
            --(*this);
            return cpy;
        }

        /// Standard dereferencing operator.
        value_type operator*() const {
#ifndef NDEBUG
            assert(this->heh_.is_valid());
            value_type res = (this->*Handle2Value)();
            assert(res.is_valid());
            return res;
#else
            return (this->*Handle2Value)();
#endif
        }

        /**
         * @brief Pointer dereferentiation.
         *
         * This returns a pointer which points to a handle
         * that loses its validity once this dereferentiation is
         * invoked again. Thus, do not store the result of
         * this operation.
         */
        pointer operator->() const {
            pointer_deref_value = **this;
            return &pointer_deref_value;
        }

        GenericCirculatorT &operator=(const GenericCirculatorT &rhs) {
            GenericCirculatorBaseT<Mesh>::operator=(rhs);
            return *this;
        };

        bool operator==(const GenericCirculatorT &rhs) const {
            return GenericCirculatorBaseT<Mesh>::operator==(rhs);
        }

        bool operator!=(const GenericCirculatorT &rhs) const {
            return GenericCirculatorBaseT<Mesh>::operator!=(rhs);
        }

        bool is_valid() const {
            return GenericCirculator_ValueHandleFns::is_valid(this->heh_, this->lap_counter_);
        }

        template<typename STREAM>
        friend STREAM &operator<< (STREAM &s, const GenericCirculatorT &self) {
            return s << self.mesh_ << ", " << self.start_.idx() << ", " << self.heh_.idx() << ", " << self.lap_counter_;
        }

    private:
        mutable value_type pointer_deref_value;
};

//////////////////////////////////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////           OLD           ///////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////////////////////////////////
// OLD CIRCULATORS
// deprecated circulators, will be removed soon
// if you remove these circulators and go to the old ones, PLEASE ENABLE FOLLOWING UNITTESTS:
//
// OpenMeshTrimeshCirculatorVertexIHalfEdge.VertexIHalfEdgeIterCheckInvalidationAtEnds
// OpenMeshTrimeshCirculatorVertexEdge.VertexEdgeIterCheckInvalidationAtEnds
// OpenMeshTrimeshCirculatorVertexVertex.VertexVertexIterCheckInvalidationAtEnds
// OpenMeshTrimeshCirculatorVertexOHalfEdge.VertexOHalfEdgeIterCheckInvalidationAtEnds
// OpenMeshTrimeshCirculatorVertexFace.VertexFaceIterCheckInvalidationAtEnds
// OpenMeshTrimeshCirculatorVertexFace.VertexFaceIterWithoutHolesDecrement
// OpenMeshTrimeshCirculatorFaceEdge.FaceEdgeIterCheckInvalidationAtEnds
// OpenMeshTrimeshCirculatorFaceFace.FaceFaceIterCheckInvalidationAtEnds
// OpenMeshTrimeshCirculatorFaceHalfEdge.FaceHalfedgeIterWithoutHolesIncrement
// OpenMeshTrimeshCirculatorFaceVertex.FaceVertexIterCheckInvalidationAtEnds
// OpenMeshTrimeshCirculatorFaceHalfEdge.FaceHalfedgeIterCheckInvalidationAtEnds
//

template<class Mesh, class CenterEntityHandle, class ValueHandle>
class GenericCirculator_ValueHandleFnsT_DEPRECATED {
    public:
        inline static bool is_valid(const typename Mesh::HalfedgeHandle &heh,const typename Mesh::HalfedgeHandle &start, const int lap_counter) {
            return ( heh.is_valid() && ((start != heh) || (lap_counter == 0 )) );
        }
        inline static void init(const Mesh*, typename Mesh::HalfedgeHandle&, typename Mesh::HalfedgeHandle&, int&) {};
        inline static void increment(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            GenericCirculator_CenterEntityFnsT<Mesh, CenterEntityHandle, true>::increment(mesh, heh, start, lap_counter);
        }
        inline static void decrement(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            GenericCirculator_CenterEntityFnsT<Mesh, CenterEntityHandle, true>::decrement(mesh, heh, start, lap_counter);
        }
};

template<class Mesh, class CenterEntityHandle>
class GenericCirculator_ValueHandleFnsT_DEPRECATED<Mesh, CenterEntityHandle, typename Mesh::FaceHandle> {
    public:
        typedef GenericCirculator_DereferenciabilityCheckT<Mesh, CenterEntityHandle, typename Mesh::FaceHandle> GenericCirculator_DereferenciabilityCheck;

        inline static bool is_valid(const typename Mesh::HalfedgeHandle &heh, const typename Mesh::HalfedgeHandle &start, const int lap_counter) {
            return ( heh.is_valid() &&  ((start != heh) || (lap_counter == 0 )));
        }
        inline static void init(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            if (heh.is_valid() && !GenericCirculator_DereferenciabilityCheck::isDereferenciable(mesh, heh) && lap_counter == 0 )
                increment(mesh, heh, start, lap_counter);
        };
        inline static void increment(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            do {
                GenericCirculator_CenterEntityFnsT<Mesh, CenterEntityHandle, true>::increment(mesh, heh, start, lap_counter);
            } while (is_valid(heh, start, lap_counter) && !GenericCirculator_DereferenciabilityCheck::isDereferenciable(mesh, heh));
        }
        inline static void decrement(const Mesh *mesh, typename Mesh::HalfedgeHandle &heh, typename Mesh::HalfedgeHandle &start, int &lap_counter) {
            do {
                GenericCirculator_CenterEntityFnsT<Mesh, CenterEntityHandle, true>::decrement(mesh, heh, start, lap_counter);
            } while (is_valid(heh, start, lap_counter) && !GenericCirculator_DereferenciabilityCheck::isDereferenciable(mesh, heh));
        }
};

template<class Mesh, class CenterEntityHandle, class ValueHandle,
        ValueHandle (GenericCirculatorBaseT<Mesh>::*Handle2Value)() const>
class GenericCirculatorT_DEPRECATED : protected GenericCirculatorBaseT<Mesh> {
    public:
        typedef std::ptrdiff_t difference_type;
        typedef ValueHandle value_type;
        typedef const value_type& reference;
        typedef const value_type* pointer;
        typedef std::bidirectional_iterator_tag iterator_category;

        typedef typename GenericCirculatorBaseT<Mesh>::mesh_ptr mesh_ptr;
        typedef typename GenericCirculatorBaseT<Mesh>::mesh_ref mesh_ref;
        typedef GenericCirculator_ValueHandleFnsT_DEPRECATED<Mesh, CenterEntityHandle, ValueHandle> GenericCirculator_ValueHandleFns;

    public:
        GenericCirculatorT_DEPRECATED() {}
        GenericCirculatorT_DEPRECATED(mesh_ref mesh, CenterEntityHandle start, bool end = false) :
            GenericCirculatorBaseT<Mesh>(mesh, mesh.halfedge_handle(start), end) {

          GenericCirculator_ValueHandleFns::init(this->mesh_, this->heh_, this->start_, this->lap_counter_);
        }
        GenericCirculatorT_DEPRECATED(mesh_ref mesh, HalfedgeHandle heh, bool end = false) :
            GenericCirculatorBaseT<Mesh>(mesh, heh, end) {

          GenericCirculator_ValueHandleFns::init(this->mesh_, this->heh_, this->start_, this->lap_counter_);
        }
        GenericCirculatorT_DEPRECATED(const GenericCirculatorT_DEPRECATED &rhs) : GenericCirculatorBaseT<Mesh>(rhs) {}

        GenericCirculatorT_DEPRECATED& operator++() {
            assert(this->mesh_);
            GenericCirculator_ValueHandleFns::increment(this->mesh_, this->heh_, this->start_, this->lap_counter_);
            return *this;
        }
#ifndef NO_DECREMENT_DEPRECATED_WARNINGS
#define DECREMENT_DEPRECATED_WARNINGS_TEXT "The current decrement operator has the unintended behavior that it stays\
    valid when iterating below the start and will visit the first entity\
    twice before getting invalid. Furthermore it gets valid again, if you\
    increment at the end.\
    When you are sure that you don't iterate below the start anywhere in\
    your code or rely on this behaviour, you can disable this warning by\
    setting the define NO_DECREMENT_DEPRECATED_WARNINGS at the command line (or enable it via the\
    cmake flags).\
    To be save, you can use the CW/CCW circulator definitions, which behave\
    the same as the original ones, without the previously mentioned issues."

        DEPRECATED( DECREMENT_DEPRECATED_WARNINGS_TEXT )
#endif // NO_DECREMENT_DEPRECATED_WARNINGS
        GenericCirculatorT_DEPRECATED& operator--() {
            assert(this->mesh_);
            GenericCirculator_ValueHandleFns::decrement(this->mesh_, this->heh_, this->start_, this->lap_counter_);
            return *this;
        }

        /// Post-increment
        GenericCirculatorT_DEPRECATED operator++(int) {
            assert(this->mesh_);
            GenericCirculatorT_DEPRECATED cpy(*this);
            ++(*this);
            return cpy;
        }

        /// Post-decrement
#ifndef NO_DECREMENT_DEPRECATED_WARNINGS
        DEPRECATED( DECREMENT_DEPRECATED_WARNINGS_TEXT )
#undef DECREMENT_DEPRECATED_WARNINGS_TEXT
#endif //NO_DECREMENT_DEPRECATED_WARNINGS
        GenericCirculatorT_DEPRECATED operator--(int) {
            assert(this->mesh_);
            GenericCirculatorT_DEPRECATED cpy(*this);
            --(*this);
            return cpy;
        }

        /// Standard dereferencing operator.
        value_type operator*() const {
#ifndef NDEBUG
            assert(this->heh_.is_valid());
            value_type res = (this->*Handle2Value)();
            assert(res.is_valid());
            return res;
#else
            return (this->*Handle2Value)();
#endif
        }

        /**
         * @brief Pointer dereferentiation.
         *
         * This returns a pointer which points to a handle
         * that loses its validity once this dereferentiation is
         * invoked again. Thus, do not store the result of
         * this operation.
         */
        pointer operator->() const {
            pointer_deref_value = **this;
            return &pointer_deref_value;
        }

        GenericCirculatorT_DEPRECATED &operator=(const GenericCirculatorT_DEPRECATED &rhs) {
            GenericCirculatorBaseT<Mesh>::operator=(rhs);
            return *this;
        };

        bool operator==(const GenericCirculatorT_DEPRECATED &rhs) const {
            return GenericCirculatorBaseT<Mesh>::operator==(rhs);
        }

        bool operator!=(const GenericCirculatorT_DEPRECATED &rhs) const {
            return GenericCirculatorBaseT<Mesh>::operator!=(rhs);
        }

        bool is_valid() const {
            return GenericCirculator_ValueHandleFns::is_valid(this->heh_,this->start_, this->lap_counter_);
        }

        DEPRECATED("current_halfedge_handle() is an implementation detail and should not be accessed from outside the iterator class.")
        /**
         * \deprecated
         * current_halfedge_handle() is an implementation detail and should not
         * be accessed from outside the iterator class.
         */
        const HalfedgeHandle &current_halfedge_handle() const {
            return this->heh_;
        }

        DEPRECATED("Do not use this error prone implicit cast. Compare to end-iterator or use is_valid(), instead.")
        /**
         * \deprecated
         * Do not use this error prone implicit cast. Compare to the
         * end-iterator or use is_valid() instead.
         */
        operator bool() const {
            return is_valid();
        }

        /**
         * \brief Return the handle of the current target.
         * \deprecated
         * This function clutters your code. Use dereferencing operators -> and * instead.
         */
        DEPRECATED("This function clutters your code. Use dereferencing operators -> and * instead.")
        value_type handle() const {
          return **this;
        }

        /**
         * \brief Cast to the handle of the current target.
         * \deprecated
         * Implicit casts of iterators are unsafe. Use dereferencing operators
         * -> and * instead.
         */
        DEPRECATED("Implicit casts of iterators are unsafe. Use dereferencing operators -> and * instead.")
        operator value_type() const {
          return **this;
        }

        template<typename STREAM>
        friend STREAM &operator<< (STREAM &s, const GenericCirculatorT_DEPRECATED &self) {
            return s << self.mesh_ << ", " << self.start_.idx() << ", " << self.heh_.idx() << ", " << self.lap_counter_;
        }

    private:
        mutable value_type pointer_deref_value;
};

} // namespace Iterators
} // namespace OpenMesh

#endif
