ElementTraits.hpp

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/*CXXR $Id: ElementTraits.hpp 1375 2013-04-15 17:16:50Z arr $
 *CXXR
 *CXXR This file is part of CXXR, a project to refactor the R interpreter
 *CXXR into C++.  It may consist in whole or in part of program code and
 *CXXR documentation taken from the R project itself, incorporated into
 *CXXR CXXR (and possibly MODIFIED) under the terms of the GNU General Public
 *CXXR Licence.
 *CXXR 
 *CXXR CXXR is Copyright (C) 2008-13 Andrew R. Runnalls, subject to such other
 *CXXR copyrights and copyright restrictions as may be stated below.
 *CXXR 
 *CXXR CXXR is not part of the R project, and bugs and other issues should
 *CXXR not be reported via r-bugs or other R project channels; instead refer
 *CXXR to the CXXR website.
 *CXXR */

/*
 *  R : A Computer Language for Statistical Data Analysis
 *
 *  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 2.1 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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, a copy is available at
 *  http://www.r-project.org/Licenses/
 */

#ifndef ELEMENTTRAITS_HPP
#define ELEMENTTRAITS_HPP 1

#include <boost/mpl/bool.hpp>
#include "CXXR/GCNode.hpp"

namespace CXXR {
    namespace ElementTraits {
        template <typename T>
        struct Data {
            typedef T type;

            static const type& get(const T& t)
            {
                return t;
            }
        };  // struct Data

        template <typename T>
        inline const typename ElementTraits::Data<T>::type&
        data(const T& t)
        {
            return Data<T>::get(t);
        }

        template <typename T>
        struct DetachReferents : std::unary_function<T, void> {
            void operator()(T& t) const
            {}
        };

        template <typename T>
        struct HasReferents : boost::mpl::false_
        {};

        template <typename T>
        struct MustConstruct : boost::mpl::false_
        {};

        template <typename T>
        struct MustDestruct : boost::mpl::false_
        {};

        template <typename T>
        struct Serialize {
            template <class Archive>
            void operator()(Archive& ar, T& item)
            {
                typename ElementTraits::Data<T>::type payload
                    = ElementTraits::data(item); 
                ar & boost::serialization::make_nvp("item", payload);
                item = payload;
            }
        };
            
        template <typename T>
        struct VisitReferents : std::unary_function<T, void> {
            VisitReferents(GCNode::const_visitor* v)
            {}

            void operator()(const T& t) const
            {}
        };

        template <typename T>
        struct NAFunc {
            const T& operator()() const;
        };

        template <typename T> struct IsNA {
            bool operator()(const T& t) const
            {
                return t == NAFunc<T>()();
            }
        };

        template <typename T>
        inline bool hasDistinctNA()
        {
            return isNA(NAFunc<T>()());
        }
    }  // namespace ElementTraits

    template <typename T> bool isNA(const T& t)
    {
        return ElementTraits::IsNA<T>()(t);
    }

    template <typename T> const T& NA()
    {
        return ElementTraits::NAFunc<T>()();
    }
}  // namespace CXXR;

#endif  // ELEMENTTRAITS_HPP