#ifndef BOOST_NUMERIC_CPP_HPP
#define BOOST_NUMERIC_CPP_HPP
// 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)
// policy which creates results types equal to that of C++ promotions.
// Using the policy will permit the program to build and run in release
// mode which is identical to that in debug mode except for the fact
// that errors aren't trapped.
#include <type_traits> // integral constant, remove_cv, conditional
#include <limits>
#include <boost/integer.hpp> // integer type selection
#include "safe_common.hpp"
#include "checked_result.hpp"
namespace boost {
namespace safe_numerics {
// in C++ the following rules govern integer arithmetic
// This policy is use to emulate another compiler/machine architecture
// For example, a Z80 has 8 bit char, 16 bit short, 16 bit int, 32 bit long. So one
// would use cpp<8, 16, 16, 32, 32> to test programs destined to run on a Z80
// Follow section 5 of the standard.
template<
int CharBits,
int ShortBits,
int IntBits,
int LongBits,
int LongLongBits
>
struct cpp {
public:
using local_char_type = typename boost::int_t<CharBits>::exact;
using local_short_type = typename boost::int_t<ShortBits>::exact;
using local_int_type = typename boost::int_t<IntBits>::exact;
using local_long_type = typename boost::int_t<LongBits>::exact;
using local_long_long_type = typename boost::int_t<LongLongBits>::exact;
template<class T>
using rank =
typename std::conditional<
std::is_same<local_char_type, typename std::make_signed<T>::type>::value,
std::integral_constant<int, 1>,
typename std::conditional<
std::is_same<local_short_type, typename std::make_signed<T>::type>::value,
std::integral_constant<int, 2>,
typename std::conditional<
std::is_same<local_int_type, typename std::make_signed<T>::type>::value,
std::integral_constant<int, 3>,
typename std::conditional<
std::is_same<local_long_type, typename std::make_signed<T>::type>::value,
std::integral_constant<int, 4>,
typename std::conditional<
std::is_same<local_long_long_type, typename std::make_signed<T>::type>::value,
std::integral_constant<int, 5>,
std::integral_constant<int, 6> // catch all - never promote integral
>::type >::type >::type >::type >::type;
// section 4.5 integral promotions
// convert smaller of two types to the size of the larger
template<class T, class U>
using higher_ranked_type = typename std::conditional<
(rank<T>::value < rank<U>::value),
U,
T
>::type;
template<class T, class U>
using copy_sign = typename std::conditional<
std::is_signed<U>::value,
typename std::make_signed<T>::type,
typename std::make_unsigned<T>::type
>::type;
template<class T>
using integral_promotion = copy_sign<
higher_ranked_type<local_int_type, T>,
T
>;
// note presumption that T & U don't have he same sign
// if that's not true, these won't work
template<class T, class U>
using select_signed = typename std::conditional<
std::numeric_limits<T>::is_signed,
T,
U
>::type;
template<class T, class U>
using select_unsigned = typename std::conditional<
std::numeric_limits<T>::is_signed,
U,
T
>::type;
// section 5 clause 11 - usual arithmetic conversions
template<typename T, typename U>
using usual_arithmetic_conversions =
// clause 0 - if both operands have the same type
typename std::conditional<
std::is_same<T, U>::value,
// no further conversion is needed
T,
// clause 1 - otherwise if both operands have the same sign
typename std::conditional<
std::numeric_limits<T>::is_signed
== std::numeric_limits<U>::is_signed,
// convert to the higher ranked type
higher_ranked_type<T, U>,
// clause 2 - otherwise if the rank of he unsigned type exceeds
// the rank of the of the signed type
typename std::conditional<
rank<select_unsigned<T, U>>::value
>= rank< select_signed<T, U>>::value,
// use unsigned type
select_unsigned<T, U>,
// clause 3 - otherwise if the type of the signed integer type can
// represent all the values of the unsigned type
typename std::conditional<
std::numeric_limits< select_signed<T, U>>::digits >=
std::numeric_limits< select_unsigned<T, U>>::digits,
// use signed type
select_signed<T, U>,
// clause 4 - otherwise use unsigned version of the signed type
std::make_signed< select_signed<T, U>>
>::type >::type >::type
>;
template<typename T, typename U>
using result_type = typename usual_arithmetic_conversions<
integral_promotion<typename base_type<T>::type>,
integral_promotion<typename base_type<U>::type>
>::type;
public:
template<typename T, typename U>
struct addition_result {
using type = result_type<T, U>;
};
template<typename T, typename U>
struct subtraction_result {
using type = result_type<T, U>;
};
template<typename T, typename U>
struct multiplication_result {
using type = result_type<T, U>;
};
template<typename T, typename U>
struct division_result {
using type = result_type<T, U>;
};
template<typename T, typename U>
struct modulus_result {
using type = result_type<T, U>;
};
// note: comparison_result (<, >, ...) is special.
// The return value is always a bool. The type returned here is
// the intermediate type applied to make the values comparable.
template<typename T, typename U>
struct comparison_result {
using type = result_type<T, U>;
};
template<typename T, typename U>
struct left_shift_result {
using type = result_type<T, U>;
};
template<typename T, typename U>
struct right_shift_result {
using type = result_type<T, U>;
};
template<typename T, typename U>
struct bitwise_and_result {
using type = result_type<T, U>;
};
template<typename T, typename U>
struct bitwise_or_result {
using type = result_type<T, U>;
};
template<typename T, typename U>
struct bitwise_xor_result {
using type = result_type<T, U>;
};
};
} // safe_numerics
} // boost
#endif // BOOST_NUMERIC_cpp_HPP