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add detail/float.hpp

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bolero-MURAKAMI 2012-04-18 17:46:27 +09:00
parent 22f13db2a0
commit 80763fd432
2 changed files with 124 additions and 54 deletions
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118
sprout/detail/float.hpp Normal file
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#ifndef SPROUT_DETAIL_FLOAT_HPP
#define SPROUT_DETAIL_FLOAT_HPP
#include <cmath>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/utility/enabler_if.hpp>
namespace sprout {
namespace detail {
//
// float_pow10
//
template<typename FloatType>
inline SPROUT_CONSTEXPR FloatType
float_pow10_positive(int exponent) {
return exponent ? sprout::detail::float_pow10_positive<FloatType>(exponent - 1) * 10
: FloatType(1)
;
}
template<typename FloatType>
inline SPROUT_CONSTEXPR FloatType
float_pow10_negative(int exponent) {
return exponent ? sprout::detail::float_pow10_negative<FloatType>(exponent + 1) / 10
: FloatType(1)
;
}
template<typename FloatType, typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler>
inline SPROUT_CONSTEXPR FloatType
float_pow10(int exponent) {
return exponent < 0
? sprout::detail::float_pow10_negative<FloatType>(exponent)
: sprout::detail::float_pow10_positive<FloatType>(exponent)
;
}
//
// float_exponent10
//
template<typename FloatType>
inline SPROUT_CONSTEXPR int
float_exponent10_positive(FloatType val) {
return val < 10 ? 0
: 1 + sprout::detail::float_exponent10_positive(val / 10)
;
}
template<typename FloatType>
inline SPROUT_CONSTEXPR int
float_exponent10_negative(FloatType val) {
return val < 1 ? 1 + sprout::detail::float_exponent10_negative(val * 10)
: 0
;
}
template<typename FloatType, typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler>
inline SPROUT_CONSTEXPR int
float_exponent10(FloatType val) {
return val < 0
? val > -1
? sprout::detail::float_exponent10_negative(-val)
: sprout::detail::float_exponent10_positive(-val)
: val < 1
? sprout::detail::float_exponent10_negative(val)
: sprout::detail::float_exponent10_positive(val)
;
}
//
// float_digits
//
template<typename FloatType, typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler>
inline SPROUT_CONSTEXPR int
float_digits_impl(FloatType val) {
return val < 1 ? 0
: 1 + sprout::detail::float_digits_impl(val / 10)
;
}
template<typename FloatType>
inline SPROUT_CONSTEXPR int
float_digits(FloatType val) {
return val < 0
? val > -1 ? 1 : 1 + sprout::detail::float_digits_impl(-val / 10)
: val < 1 ? 1 : 1 + sprout::detail::float_digits_impl(val / 10)
;
}
//
// float_digit_at
//
template<typename FloatType, typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler>
inline SPROUT_CONSTEXPR int
float_digit_of_impl(FloatType val) {
using std::floor;
return static_cast<int>((val - floor(val)) * 10);
}
template<typename FloatType>
inline SPROUT_CONSTEXPR int
float_digit_at(FloatType val, int digits) {
return sprout::detail::float_digit_of_impl(val / sprout::detail::float_pow10<FloatType>(digits + 1));
}
//
// float_round_at
//
template<typename FloatType, typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler>
inline SPROUT_CONSTEXPR FloatType
float_round_impl(FloatType val, FloatType p10) {
using std::round;
return round(val * p10) / p10;
}
template<typename FloatType>
inline SPROUT_CONSTEXPR FloatType
float_round_at(FloatType val, int digits) {
return sprout::detail::float_round_impl(val, sprout::detail::float_pow10<FloatType>(digits));
}
} // namespace detail
} // namespace sprout
#endif // #ifndef SPROUT_DETAIL_FLOAT_HPP