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Sprout/sprout/cstdlib/str_to_float.hpp
2017-07-29 14:20:01 +09:00

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/*=============================================================================
Copyright (c) 2011-2017 Bolero MURAKAMI
https://github.com/bolero-MURAKAMI/Sprout
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)
=============================================================================*/
#ifndef SPROUT_CSTDLIB_STR_TO_FLOAT_HPP
#define SPROUT_CSTDLIB_STR_TO_FLOAT_HPP
#include <cstdlib>
#include <cmath>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/workaround/std/cstddef.hpp>
#include <sprout/limits.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/ctype/ascii.hpp>
#include <sprout/detail/char_literal.hpp>
#include <sprout/detail/char_type_of_consecutive.hpp>
namespace sprout {
namespace detail {
template<typename FloatType, typename NullTerminatedIterator>
inline SPROUT_CONSTEXPR FloatType
str_to_float_impl_scale(
NullTerminatedIterator const& str,
bool negative,
FloatType number = FloatType(),
std::size_t num_digits = 0,
std::size_t num_decimals = 0,
long exponent = 0,
long n = 0,
FloatType p10 = FloatType(10)
)
{
return n ? sprout::detail::str_to_float_impl_scale<FloatType>(
str,
negative,
n & 1 ? (exponent < 0 ? number / p10 : number * p10) : number,
num_digits,
num_decimals,
exponent,
n >> 1,
p10 * p10
)
: number
;
}
template<typename FloatType, typename NullTerminatedIterator>
inline SPROUT_CONSTEXPR FloatType
str_to_float_impl_exponent_2(
NullTerminatedIterator const& str,
bool negative,
FloatType number = FloatType(),
std::size_t num_digits = 0,
std::size_t num_decimals = 0,
long exponent = 0
)
{
return exponent >= sprout::numeric_limits<FloatType>::min_exponent
&& exponent <= sprout::numeric_limits<FloatType>::max_exponent
? sprout::detail::str_to_float_impl_scale<FloatType>(
str,
negative,
number,
num_digits,
num_decimals,
exponent,
exponent < 0 ? -exponent : exponent
)
: HUGE_VAL
;
}
template<typename FloatType, typename NullTerminatedIterator>
inline SPROUT_CONSTEXPR FloatType
str_to_float_impl_exponent_1(
NullTerminatedIterator const& str,
bool negative,
FloatType number = FloatType(),
std::size_t num_digits = 0,
std::size_t num_decimals = 0,
long exponent = 0,
long n = 0
)
{
typedef typename std::iterator_traits<NullTerminatedIterator>::value_type char_type;
SPROUT_STATIC_ASSERT(sprout::detail::is_char_type_of_consecutive_digits<char_type>::value);
return sprout::ascii::isdigit(*str) ? sprout::detail::str_to_float_impl_exponent_1<FloatType>(
sprout::next(str),
negative,
number,
num_digits,
num_decimals,
exponent,
n * 10 + (*str - SPROUT_CHAR_LITERAL('0', char_type))
)
: sprout::detail::str_to_float_impl_exponent_2<FloatType>(
str,
negative,
number,
num_digits,
num_decimals,
negative ? exponent + n : exponent - n
)
;
}
template<typename FloatType, typename NullTerminatedIterator>
inline SPROUT_CONSTEXPR FloatType
str_to_float_impl_exponent(
NullTerminatedIterator const& str,
bool negative,
FloatType number = FloatType(),
std::size_t num_digits = 0,
std::size_t num_decimals = 0,
long exponent = 0
)
{
typedef typename std::iterator_traits<NullTerminatedIterator>::value_type char_type;
return (*str == SPROUT_CHAR_LITERAL('e', char_type) || *str == SPROUT_CHAR_LITERAL('E', char_type))
? *sprout::next(str) == SPROUT_CHAR_LITERAL('-', char_type)
? sprout::detail::str_to_float_impl_exponent_1<FloatType>(
sprout::next(str, 2),
true,
number,
num_digits,
num_decimals,
exponent
)
: sprout::detail::str_to_float_impl_exponent_1<FloatType>(
sprout::next(str, 2),
false,
number,
num_digits,
num_decimals,
exponent
)
: sprout::detail::str_to_float_impl_exponent_2<FloatType>(
str,
negative,
number,
num_digits,
num_decimals,
exponent
)
;
}
template<typename FloatType, typename NullTerminatedIterator>
inline SPROUT_CONSTEXPR FloatType
str_to_float_impl_decimal_1(
NullTerminatedIterator const& str,
bool negative,
FloatType number = FloatType(),
std::size_t num_digits = 0,
std::size_t num_decimals = 0,
long exponent = 0
)
{
return num_digits == 0 ? FloatType()
: sprout::detail::str_to_float_impl_exponent<FloatType>(
str,
negative,
negative ? -number : number,
num_digits,
num_decimals,
exponent
)
;
}
template<typename FloatType, typename NullTerminatedIterator>
inline SPROUT_CONSTEXPR FloatType
str_to_float_impl_decimal(
NullTerminatedIterator const& str,
bool negative,
FloatType number = FloatType(),
std::size_t num_digits = 0,
std::size_t num_decimals = 0,
long exponent = 0
)
{
typedef typename std::iterator_traits<NullTerminatedIterator>::value_type char_type;
SPROUT_STATIC_ASSERT(sprout::detail::is_char_type_of_consecutive_digits<char_type>::value);
return sprout::ascii::isdigit(*str) ? sprout::detail::str_to_float_impl_decimal<FloatType>(
sprout::next(str),
negative,
number * 10 + (*str - SPROUT_CHAR_LITERAL('0', char_type)),
num_digits + 1,
num_decimals + 1,
exponent
)
: sprout::detail::str_to_float_impl_decimal_1<FloatType>(
str,
negative,
number,
num_digits,
num_decimals,
exponent - num_decimals
)
;
}
template<typename FloatType, typename NullTerminatedIterator>
inline SPROUT_CONSTEXPR FloatType
str_to_float_impl(
NullTerminatedIterator const& str,
bool negative,
FloatType number = FloatType(),
std::size_t num_digits = 0
)
{
typedef typename std::iterator_traits<NullTerminatedIterator>::value_type char_type;
SPROUT_STATIC_ASSERT(sprout::detail::is_char_type_of_consecutive_digits<char_type>::value);
return sprout::ascii::isdigit(*str) ? sprout::detail::str_to_float_impl<FloatType>(
sprout::next(str),
negative,
number * 10 + (*str - SPROUT_CHAR_LITERAL('0', char_type)),
num_digits + 1
)
: *str == SPROUT_CHAR_LITERAL('.', char_type) ? sprout::detail::str_to_float_impl_decimal<FloatType>(
sprout::next(str),
negative,
number,
num_digits
)
: sprout::detail::str_to_float_impl_decimal_1<FloatType>(
str,
negative,
number,
num_digits
)
;
}
template<typename FloatType, typename NullTerminatedIterator>
inline SPROUT_CONSTEXPR FloatType
str_to_float(NullTerminatedIterator const& str) {
typedef typename std::iterator_traits<NullTerminatedIterator>::value_type char_type;
return sprout::ascii::isspace(*str)
? sprout::detail::str_to_float<FloatType>(sprout::next(str))
: *str == SPROUT_CHAR_LITERAL('-', char_type)
? sprout::detail::str_to_float_impl<FloatType>(sprout::next(str), true)
: *str == SPROUT_CHAR_LITERAL('+', char_type)
? sprout::detail::str_to_float_impl<FloatType>(sprout::next(str), false)
: sprout::detail::str_to_float_impl<FloatType>(str, false)
;
}
template<typename FloatType, typename NullTerminatedIterator, typename CharPtr>
inline SPROUT_CONSTEXPR FloatType
str_to_float(NullTerminatedIterator const& str, CharPtr* endptr) {
return !endptr ? sprout::detail::str_to_float<FloatType>(str)
#if defined(__MINGW32__)
: std::is_same<typename std::remove_cv<FloatType>::type, float>::value ? ::strtof(&*str, endptr)
: std::is_same<typename std::remove_cv<FloatType>::type, double>::value ? std::strtod(&*str, endptr)
: ::strtold(&*str, endptr)
#else
: std::is_same<typename std::remove_cv<FloatType>::type, float>::value ? std::strtof(&*str, endptr)
: std::is_same<typename std::remove_cv<FloatType>::type, double>::value ? std::strtod(&*str, endptr)
: std::strtold(&*str, endptr)
#endif
;
}
} // namespace detail
//
// str_to_float
//
template<typename FloatType, typename Char>
inline SPROUT_CONSTEXPR typename std::enable_if<
std::is_floating_point<FloatType>::value,
FloatType
>::type
str_to_float(Char const* str, Char** endptr) {
return sprout::detail::str_to_float<FloatType>(str, endptr);
}
template<typename FloatType, typename Char>
inline SPROUT_CONSTEXPR typename std::enable_if<
std::is_floating_point<FloatType>::value,
FloatType
>::type
str_to_float(Char const* str, std::nullptr_t) {
return sprout::detail::str_to_float<FloatType>(str);
}
template<typename FloatType, typename Char>
inline SPROUT_CONSTEXPR typename std::enable_if<
std::is_floating_point<FloatType>::value,
FloatType
>::type
str_to_float(Char const* str) {
return sprout::detail::str_to_float<FloatType>(str);
}
} // namespace sprout
#endif // #ifndef SPROUT_CSTDLIB_STR_TO_FLOAT_HPP