throwing.h

 
//          Copyright John McFarlane 2018.
// 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_OVERFLOW_THROWING_H)
#define CNL_IMPL_OVERFLOW_THROWING_H
 
#include "../polarity.h"
#include "../throw_exception.h"
#include "is_overflow_tag.h"
#include "is_tag.h"
#include "overflow_operator.h"
 
#include <stdexcept>
 
namespace cnl::_impl {
    struct throwing_overflow_tag
        : _impl::homogeneous_deduction_tag_base
        , _impl::homogeneous_operator_tag_base {
    };
 
    template<>
    struct is_overflow_tag<throwing_overflow_tag> : std::true_type {
    };
 
    template<typename Operator>
    struct overflow_operator<Operator, throwing_overflow_tag, polarity::positive> {
        template<typename Destination, typename Source>
        [[nodiscard]] constexpr auto operator()(Source const&) const
        {
            return throw_exception<Destination, std::overflow_error>("positive overflow");
        }
 
        template<class... Operands>
        [[nodiscard]] constexpr auto operator()(Operands const&...) const
        {
            return throw_exception<op_result<Operator, Operands...>, std::overflow_error>(
                    "positive overflow");
        }
    };
 
    template<typename Operator>
    struct overflow_operator<Operator, throwing_overflow_tag, polarity::negative> {
        template<typename Destination, typename Source>
        [[nodiscard]] constexpr auto operator()(Source const&) const
        {
            return throw_exception<Destination, std::overflow_error>("negative overflow");
        }
 
        template<class... Operands>
        [[nodiscard]] constexpr auto operator()(Operands const&...) const
        {
            return throw_exception<op_result<Operator, Operands...>, std::overflow_error>(
                    "negative overflow");
        }
    };
}
 
#endif  // CNL_IMPL_OVERFLOW_THROWING_H