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add float_to_string_exp

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This commit is contained in:
bolero-MURAKAMI 2012-04-19 15:39:01 +09:00
parent 47ec95c7ff
commit 9ff67fe582
1 changed files with 85 additions and 0 deletions
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85
sprout/string/float_to_string.hpp
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@ -6,10 +6,13 @@
#include <limits>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/index_tuple.hpp>
#include <sprout/string/string.hpp>
#include <sprout/utility/enabler_if.hpp>
#include <sprout/detail/char_conversion.hpp>
#include <sprout/detail/int.hpp>
#include <sprout/detail/float.hpp>
#include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
namespace sprout {
namespace detail {
@ -74,6 +77,88 @@ namespace sprout {
);
}
namespace detail {
template<typename FloatType>
struct printed_float_exponent10_digits
: public std::integral_constant<
std::size_t,
NS_SSCRISK_CEL_OR_SPROUT::max(sprout::detail::int_digits(std::numeric_limits<FloatType>::max_exponent10), 2)
>
{};
} // namespace detail
//
// printed_float_exp_digits
//
template<typename FloatType>
struct printed_float_exp_digits
: public std::integral_constant<
std::size_t,
5 + sprout::detail::decimal_places_length + sprout::detail::printed_float_exponent10_digits<FloatType>::value
>
{};
namespace detail {
template<typename Elem, typename FloatType, sprout::index_t... Indexes>
inline SPROUT_CONSTEXPR sprout::basic_string<Elem, sprout::printed_float_exp_digits<FloatType>::value>
float_to_string_exp(FloatType val, bool negative, int exponent10, int e10_digits, sprout::index_tuple<Indexes...>) {
return negative ? sprout::basic_string<Elem, sprout::printed_float_exp_digits<FloatType>::value>{
{
static_cast<Elem>('-'),
(Indexes == 0 ? sprout::detail::int_to_char<Elem>(sprout::detail::float_digit_at(val, 0))
: Indexes == 1 ? static_cast<Elem>('.')
: Indexes < 2 + sprout::detail::decimal_places_length
? sprout::detail::int_to_char<Elem>(sprout::detail::float_digit_at(val, 1 - Indexes))
: Indexes == 2 + sprout::detail::decimal_places_length ? static_cast<Elem>('e')
: Indexes == 3 + sprout::detail::decimal_places_length ? static_cast<Elem>(exponent10 < 0 ? '-' : '+')
: Indexes < 4 + sprout::detail::decimal_places_length + e10_digits
? sprout::detail::int_to_char<Elem>(sprout::detail::int_digit_at(exponent10, 3 + sprout::detail::decimal_places_length + e10_digits - Indexes))
: Elem()
)...
},
static_cast<std::size_t>(5 + sprout::detail::decimal_places_length + e10_digits)
}
: sprout::basic_string<Elem, sprout::printed_float_exp_digits<FloatType>::value>{
{
(Indexes == 0 ? sprout::detail::int_to_char<Elem>(sprout::detail::float_digit_at(val, 0))
: Indexes == 1 ? static_cast<Elem>('.')
: Indexes < 2 + sprout::detail::decimal_places_length
? sprout::detail::int_to_char<Elem>(sprout::detail::float_digit_at(val, 1 - Indexes))
: Indexes == 2 + sprout::detail::decimal_places_length ? static_cast<Elem>('e')
: Indexes == 3 + sprout::detail::decimal_places_length ? static_cast<Elem>(exponent10 < 0 ? '-' : '+')
: Indexes < 4 + sprout::detail::decimal_places_length + e10_digits
? sprout::detail::int_to_char<Elem>(sprout::detail::int_digit_at(exponent10, 3 + sprout::detail::decimal_places_length + e10_digits - Indexes))
: Elem()
)...
},
static_cast<std::size_t>(4 + sprout::detail::decimal_places_length + e10_digits)
}
;
}
} // namespace detail
//
// float_to_string_exp
//
template<
typename Elem,
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR sprout::basic_string<Elem, sprout::printed_float_exp_digits<FloatType>::value>
float_to_string_exp(FloatType val) {
return sprout::detail::float_to_string_exp<Elem>(
sprout::detail::float_round_at(
(val < 0 ? -val : val) / sprout::detail::float_pow10<FloatType>(sprout::detail::float_exponent10(val)),
sprout::detail::decimal_places_length
),
val < 0,
sprout::detail::float_exponent10(val),
NS_SSCRISK_CEL_OR_SPROUT::max(sprout::detail::int_digits(sprout::detail::float_exponent10(val)), 2),
sprout::index_range<0, sprout::printed_float_exp_digits<FloatType>::value - 1>::make()
);
}
//
// to_string_of
//