// Copyright (c) 2014
// INRIA Saclay-Ile de France (France)
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v5.6.1/NewKernel_d/include/CGAL/NewKernel_d/store_kernel.h $
// $Id: store_kernel.h a03eff6 2020-04-08T16:03:18+02:00 Marc Glisse
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s)     : Marc Glisse

#ifndef CGAL_STORE_KERNEL_H
#define CGAL_STORE_KERNEL_H

#include <CGAL/assertions.h>
#include <type_traits>

namespace CGAL {
namespace internal {
BOOST_MPL_HAS_XXX_TRAIT_DEF(Do_not_store_kernel)
template<class T,bool=std::is_empty<T>::value,bool=has_Do_not_store_kernel<T>::value> struct Do_not_store_kernel {
        enum { value=false };
        typedef Tag_false type;
};
template<class T> struct Do_not_store_kernel<T,true,false> {
        enum { value=true };
        typedef Tag_true type;
};
template<class T,bool b> struct Do_not_store_kernel<T,b,true> {
        typedef typename T::Do_not_store_kernel type;
        enum { value=type::value };
};
}

template<class R_,bool=internal::Do_not_store_kernel<R_>::value>
struct Store_kernel {
        Store_kernel(){}
        Store_kernel(R_ const&){}
        enum { kernel_is_stored = false };
        R_ kernel()const{return R_();}
        typedef R_ reference_type;
        void set_kernel(R_ const&){}
};
template<class R_>
struct Store_kernel<R_,false> {
        Store_kernel():rp(0){
                CGAL_warning_msg(true,"I should know my kernel");
        }
        Store_kernel(R_ const& r):rp(&r){}
        enum { kernel_is_stored = true };
        R_ const& kernel()const{
                CGAL_warning_msg(rp!=0,"I should know my kernel");
                return *rp;
        }
        typedef R_ const& reference_type;
        void set_kernel(R_ const&r){rp=&r;}
        private:
        R_ const* rp;
};

//For a second kernel. TODO: find something more elegant
template<class R_,bool=internal::Do_not_store_kernel<R_>::value>
struct Store_kernel2 {
        Store_kernel2(){}
        Store_kernel2(R_ const&){}
        enum { kernel2_is_stored = false };
        R_ kernel2()const{return R_();}
        typedef R_ reference2_type;
        void set_kernel2(R_ const&){}
};
template<class R_>
struct Store_kernel2<R_,false> {
        Store_kernel2(){
                //CGAL_warning_msg(true,"I should know my kernel");
        }
        Store_kernel2(R_ const& r):rp(&r){}
        enum { kernel2_is_stored = true };
        R_ const& kernel2()const{
                CGAL_warning_msg(rp==0,"I should know my kernel");
                return *rp;
        }
        typedef R_ const& reference2_type;
        void set_kernel2(R_ const&r){rp=&r;}
        private:
        R_ const* rp;
};
}
#define CGAL_BASE_INIT(X,Y) \
        X():Y(){} \
        X(R_ const&r):Y(r){}
#define CGAL_FUNCTOR_INIT_STORE(X) CGAL_BASE_INIT(X,Store_kernel<R_>)
#define CGAL_FUNCTOR_INIT_IGNORE(X) \
        X(){} \
        X(R_ const&){}

#endif // CGAL_STORE_KERNEL_H

