ref.h

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/*
  This file is part of MADNESS.

  Copyright (C) 2007,2010 Oak Ridge National Laboratory

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

  For more information please contact:

  Robert J. Harrison
  Oak Ridge National Laboratory
  One Bethel Valley Road
  P.O. Box 2008, MS-6367

  email: harrisonrj@ornl.gov
  tel:   865-241-3937
  fax:   865-572-0680


  $Id$
*/

#ifndef MADNESS_WORLD_REF_H__INCLUDED
#define MADNESS_WORLD_REF_H__INCLUDED

#include <madness/world/worldexc.h>
#include <madness/world/type_traits.h>

//  ref.hpp - ref/cref, useful helper functions
//
//  Copyright (C) 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi)
//  Copyright (C) 2001, 2002 Peter Dimov
//  Copyright (C) 2002 David Abrahams
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
//  See http://www.boost.org/libs/bind/ref.html for documentation.
//
//  Ported by JAC into madness 6/27/2012

namespace madness {
    namespace detail {


        template<class T>
        class ReferenceWrapper {
        private:
            T* t_; 

        public:
            typedef T type; 


            ReferenceWrapper() : t_(NULL) { }


            explicit ReferenceWrapper(T& t) : t_(&t) { }

            // Compiler generated copy constructor and assignment operator are OK here


            T& get() const {
                MADNESS_ASSERT(t_);
                return *t_;
            }


            operator T& () const { return get(); }


            T* get_pointer() const { return t_; }


            template <typename Archive>
            void serialize(const Archive&) {
                MADNESS_EXCEPTION("ReferenceWrapper serialization not supported.", 0);
            }

        }; // class ReferenceWrapper

    }  // namespace detail



    template<class T>
    inline detail::ReferenceWrapper<T> const ref(T& t) {  return detail::ReferenceWrapper<T>(t); }


    template<class T>
    inline detail::ReferenceWrapper<const T> const cref(const T& t) { return detail::ReferenceWrapper<const T>(t); }



    template<typename T>
    class is_reference_wrapper : public std::false_type { };

    template<typename T>
    class UnwrapReference {
    public:
        typedef T type; 
    }; // class UnwrapReference

    template<typename T>
    class is_reference_wrapper<detail::ReferenceWrapper<T> > : public std::true_type { };

    template<typename T>
    class is_reference_wrapper<detail::ReferenceWrapper<T> const> : public std::true_type { };

    template<typename T>
    class is_reference_wrapper<detail::ReferenceWrapper<T> volatile> : public std::true_type { };

    template<typename T>
    class is_reference_wrapper<detail::ReferenceWrapper<T> const volatile> : public std::true_type { };

    template<typename T>
    class UnwrapReference<detail::ReferenceWrapper<T> > {
    public:
        typedef T type;
    }; // class UnwrapReference<ReferenceWrapper<T> >

    template<typename T>
    class UnwrapReference<detail::ReferenceWrapper<T> const> {
    public:
        typedef T type;
    }; // class UnwrapReference<ReferenceWrapper<T> const>

    template<typename T>
    class UnwrapReference<detail::ReferenceWrapper<T> volatile> {
    public:
        typedef T type;
    }; // class UnwrapReference<ReferenceWrapper<T> volatile>

    template<typename T>
    class UnwrapReference<detail::ReferenceWrapper<T> const volatile> {
    public:
        typedef T type;
    }; // class UnwrapReference<ReferenceWrapper<T> const volatile>



    template <class T>
    inline typename UnwrapReference<T>::type& unwrap_ref(T& t) { return t; }


    template<class T>
    inline T* get_pointer(const detail::ReferenceWrapper<T>& r ) { return r.get_pointer(); }

    // Forward declairation
    template <typename> class Future;


    template <typename T>
    class Future<detail::ReferenceWrapper<T> > {
    private:
        detail::ReferenceWrapper<T> ref_;

        // Not needed
        Future(const Future<detail::ReferenceWrapper<T> >&);
        Future<detail::ReferenceWrapper<T> >&
        operator=(const Future<detail::ReferenceWrapper<T> >&);

    public:

        Future(const detail::ReferenceWrapper<T>& ref) :
            ref_(ref)
        { }

        // Not needed right now. Uncomment these lines if that changes.
//        Future() : ref_() { }
//        Future(const Future<detail::ReferenceWrapper<T> >& other) :
//            ref_(other.ref_)
//        { }
//        Future<detail::ReferenceWrapper<T> >&
//        operator=(const Future<detail::ReferenceWrapper<T> >& other) {
//            ref_ = other.ref_;
//            return *this;
//        }


        bool probe() const { return true; }


        void register_callback(CallbackInterface* callback) {
            callback->notify();
        }

        operator T&() const { return ref_.get(); }

    }; // class Future<detail::ReferenceWrapper<T>  >

} // namespace madness

#endif // MADNESS_WORLD_REF_H__INCLUDED