RHandle.hpp

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/*CXXR $Id: RHandle.hpp 1351 2013-03-08 15:12:28Z 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
 *  Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
 *  Copyright (C) 1999-2007   The R Development Core Team.
 *
 *  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 RHANDLE_HPP
#define RHANDLE_HPP

#include "CXXR/ElementTraits.hpp"
#include "CXXR/GCEdge.hpp"

namespace CXXR {
    class RObject;

    template <class T = RObject>
    class RHandle : public GCEdge<T> {
    public:
        RHandle()
        {}

        explicit RHandle(T* target)
            : GCEdge<T>(target)
        {}

        RHandle(const RHandle<T>& pattern)
            : GCEdge<T>(cloneOrSelf(pattern))
        {}

        RHandle<T>& operator=(const RHandle<T>& source)
        {
            GCEdge<T>::operator=(cloneOrSelf(source));
            return *this;
        }

        RHandle<T>& operator=(T* newtarget)
        {
            GCEdge<T>::operator=(newtarget);
            return *this;
        }
    private:
        static T* cloneOrSelf(T*);
    };  // class template RHandle

    // Partial specializations of ElementTraits:
    namespace ElementTraits {
        template <class T>
        struct DetachReferents<RHandle<T> >
            : std::unary_function<T, void> {
            void operator()(RHandle<T>& t) const
            {
                t = 0;
            }
        };

        template <class T>
        struct HasReferents<RHandle<T> > : boost::mpl::true_
        {};

        template <class T>
        struct MustConstruct<RHandle<T> > : boost::mpl::true_
        {};

        template <class T>
        struct MustDestruct<RHandle<T> >  : boost::mpl::true_
        {};

        template <class T>
        struct Serialize<RHandle<T> > {
            template <class Archive>
            void operator()(Archive& ar, RHandle<T>& item)
            {
                GCNPTR_SERIALIZE(ar, item);
            }
        };

        template <class T>
        class VisitReferents<RHandle<T> >
            : public std::unary_function<T, void> {
        public:
            VisitReferents(GCNode::const_visitor* v)
                : m_v(v)
            {}

            void operator()(const RHandle<T>& t) const
            {
                if (t.get())
                    (*m_v)(t);
            }
        private:
            GCNode::const_visitor* m_v;
        };

        template <class T>
        struct NAFunc<RHandle<T> > {
            const RHandle<T>& operator()() const
            {
                static RHandle<T> na;
                return na;
            }
        };

        template <class T>
        struct IsNA<RHandle<T> > {
            bool operator()(const RHandle<T>& t) const
            {
                return false;
            }
        };
    }  // namespace ElementTraits
}  // namespace CXXR


// ***** Implementations of non-inlined templated functions. *****

template <class T>
T* CXXR::RHandle<T>::cloneOrSelf(T* pattern)
{
    T* t = pattern ? static_cast<T*>(pattern->clone()) : 0;
    return (t ? t : pattern);
}

#endif // RHANDLE_HPP