custom_operator.h

 
//          Copyright John McFarlane 2019.
// 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)
 
#if !defined(CNL_IMPL_ELASTIC_TAG_GENERIC_H)
#define CNL_IMPL_ELASTIC_TAG_GENERIC_H
 
#include "../../constant.h"
#include "../custom_operator/overloads.h"
#include "../num_traits/set_digits.h"
#include "../num_traits/width.h"
#include "../numbers/set_signedness.h"
#include "definition.h"
#include "policy.h"
 
#include <type_traits>
 
namespace cnl {
    template<
            typename Source, int SrcDigits, class SrcNarrowest,
            typename Destination, int DestDigits, class DestNarrowest>
    struct custom_operator<
            _impl::convert_op,
            op_value<Source, cnl::elastic_tag<SrcDigits, SrcNarrowest>>,
            op_value<Destination, cnl::elastic_tag<DestDigits, DestNarrowest>>>
        : custom_operator<
                  _impl::convert_op,
                  op_value<Source>,
                  op_value<Destination>> {
    };
 
    template<typename Source, typename Destination, int DestDigits, class DestNarrowest>
    struct custom_operator<
            _impl::convert_op,
            op_value<Source>,
            op_value<Destination, cnl::elastic_tag<DestDigits, DestNarrowest>>> : custom_operator<_impl::convert_op, op_value<Source>, op_value<Destination>> {
    };
 
    template<typename Source, int Digits, class Narrowest, typename Destination>
    struct custom_operator<
            _impl::convert_op,
            op_value<Source, cnl::elastic_tag<Digits, Narrowest>>,
            op_value<Destination>>
        : custom_operator<_impl::convert_op, op_value<Source>, op_value<Destination>> {
    };
 
    template<
            _impl::binary_arithmetic_op Operator,
            typename Lhs, int LhsDigits, class LhsNarrowest,
            typename Rhs, int RhsDigits, class RhsNarrowest>
    struct custom_operator<
            Operator,
            op_value<Lhs, elastic_tag<LhsDigits, LhsNarrowest>>,
            op_value<Rhs, elastic_tag<RhsDigits, RhsNarrowest>>> {
        static_assert(digits_v<Lhs> >= LhsDigits, "LHS number is not wide enough");
        static_assert(digits_v<Rhs> >= RhsDigits, "RHS number is not wide enough");
 
        using result_tag = decltype(Operator{}(
                std::declval<elastic_tag<LhsDigits, LhsNarrowest>>(),
                std::declval<elastic_tag<RhsDigits, RhsNarrowest>>()));
        using result_rep = typename result_tag::rep;
 
        [[nodiscard]] constexpr auto operator()(Lhs const& lhs, Rhs const& rhs) const
        {
            return Operator()(static_cast<result_rep>(lhs), static_cast<result_rep>(rhs));
        }
    };
 
    // shift_operator of scaled_integer and scaled_integer
    template<_impl::shift_op Operator, typename Lhs, int LhsDigits, typename LhsNarrowest, typename Rhs>
    requires(!_impl::is_constant<Rhs>::value) struct custom_operator<
            Operator,
            op_value<Lhs, elastic_tag<LhsDigits, LhsNarrowest>>,
            op_value<Rhs>> {
        [[nodiscard]] constexpr auto operator()(Lhs const& lhs, Rhs const& rhs) const
        {
            return Operator{}(lhs, rhs);
        }
    };
 
    // shift_operator of scaled_integer and something else
    template<
            _impl::shift_op Operator,
            typename Lhs, int LhsDigits, typename LhsNarrowest, int RhsDigits,
            typename Rhs, typename RhsNarrowest>
    struct custom_operator<
            Operator,
            op_value<Lhs, elastic_tag<LhsDigits, LhsNarrowest>>,
            op_value<Rhs, elastic_tag<RhsDigits, RhsNarrowest>>>
        : custom_operator<
                  Operator,
                  op_value<Lhs, elastic_tag<LhsDigits, LhsNarrowest>>,
                  op_value<Rhs, _impl::native_tag>> {
    };
}
 
#endif  // CNL_IMPL_ELASTIC_TAG_GENERIC_H