Sprout/sprout/math/trunc.hpp
2013-03-18 19:12:21 +09:00

47 lines
1.5 KiB
C++

#ifndef SPROUT_MATH_TRUNC_HPP
#define SPROUT_MATH_TRUNC_HPP
#include <cstdint>
#include <limits>
#include <type_traits>
#include <stdexcept>
#include <sprout/config.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
trunc(FloatType x) {
return x == 0 ? FloatType(0)
: x == std::numeric_limits<FloatType>::infinity() ? std::numeric_limits<FloatType>::infinity()
: x == -std::numeric_limits<FloatType>::infinity() ? -std::numeric_limits<FloatType>::infinity()
: std::numeric_limits<std::uintmax_t>::max() < x || std::numeric_limits<std::uintmax_t>::max() < -x
? SPROUT_MATH_THROW_LARGE_FLOAT_ROUNDING(std::runtime_error("trunc: large float rounding."), x)
: x < 0 ? -static_cast<FloatType>(static_cast<std::uintmax_t>(-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
trunc(IntType x) {
return sprout::math::detail::trunc(static_cast<double>(x));
}
} // namespace detail
using NS_SPROUT_MATH_DETAIL::trunc;
} // namespace math
using sprout::math::trunc;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_TRUNC_HPP