Sprout/sprout/math/round.hpp
2012-11-12 17:11:48 +09:00

60 lines
1.8 KiB
C++

#ifndef SPROUT_MATH_ROUND_HPP
#define SPROUT_MATH_ROUND_HPP
#include <cstdint>
#include <limits>
#include <type_traits>
#include <stdexcept>
#include <sprout/config.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/isinf.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
template<typename FloatType>
inline SPROUT_CONSTEXPR FloatType
round_impl_positive(FloatType x, FloatType x0) {
return x - x0 < FloatType(0.5) ? x0
: x0 + 1
;
}
template<typename FloatType>
inline SPROUT_CONSTEXPR FloatType
round_impl_nagative(FloatType x, FloatType x0) {
return x0 - x < FloatType(0.5) ? x0
: x0 - 1
;
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
round(FloatType x) {
return sprout::math::isinf(x) ? x
: std::numeric_limits<std::uintmax_t>::max() < x || std::numeric_limits<std::uintmax_t>::max() < -x
? throw std::domain_error("round: Sorry, not implemented.")
: x < 0 ? sprout::math::detail::round_impl_nagative(x, -static_cast<FloatType>(static_cast<std::uintmax_t>(-x)))
: sprout::math::detail::round_impl_positive(x, static_cast<FloatType>(static_cast<std::uintmax_t>(x)))
;
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
round(IntType x) {
return sprout::math::detail::round(static_cast<double>(x));
}
} // namespace detail
using NS_SPROUT_MATH_DETAIL::round;
} // namespace math
using sprout::math::round;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_ROUND_HPP