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safe_numerics/include/native.hpp

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3.3 KiB
C++

#ifndef BOOST_NUMERIC_NATIVE_HPP
#define BOOST_NUMERIC_NATIVE_HPP
// MS compatible compilers support #pragma once
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
// Copyright (c) 2012 Robert Ramey
//
// 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)
#include <type_traits>
#include <limits>
#include "checked.hpp"
// policy which creates results types and values equal to that of C++ promotions.
// When used in conjunction with a desired exception policy, traps errors but
// does not otherwise alter the results produced by the program using it.
namespace boost {
namespace numeric {
struct native {
// Standard C++ type promotion for expressions doesn't depend
// on the operation being performed so we can just as well
// use any operation to determine it. We choose + for this
// purpose.
template<typename T, typename U>
using additive_operator_type =
decltype(
typename base_type<T>::type()
+ typename base_type<U>::type()
);
template<typename T, typename U>
using multiplicative_operator_type =
decltype(
typename base_type<T>::type()
* typename base_type<U>::type()
);
// note: right/left shift require integer arguments
template<typename T, typename U>
using bitwise_shift_operator_type =
decltype(
typename base_type<T>::type()
<< typename base_type<U>::type()
);
template<typename T, typename U>
using bitwise_logic_operator_type =
decltype(
typename base_type<T>::type()
& typename base_type<U>::type()
);
template<typename T, typename U>
struct addition_result {
using type = additive_operator_type<T, U>;
};
template<typename T, typename U>
struct subtraction_result {
using type = additive_operator_type<T, U>;
};
template<typename T, typename U>
struct multiplication_result {
using type = multiplicative_operator_type<T, U>;
};
template<typename T, typename U>
struct division_result {
using type = multiplicative_operator_type<T, U>;
};
// forward to correct divide implementation
template<class R, class T, class U>
checked_result<R>
static constexpr divide(
const T & t,
const U & u
){
return checked::divide<R>(t, u);
}
template<typename T, typename U>
struct modulus_result {
using type = multiplicative_operator_type<T, U>;
};
// forward to correct modulus implementation
template<class R, class T, class U>
checked_result<R>
static constexpr modulus(
const T & t,
const U & u
){
return checked::modulus<R>(t, u);
}
template<typename T, typename U>
struct left_shift_result {
using type = bitwise_shift_operator_type<T, U>;
};
template<typename T, typename U>
struct right_shift_result {
using type = bitwise_shift_operator_type<T, U>;
};
template<typename T, typename U>
struct bitwise_result {
using type = bitwise_logic_operator_type<T, U>;
};
};
} // numeric
} // boost
#endif // BOOST_NUMERIC_NATIVE_HPP