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Sprout/sprout/detail/math/int.hpp
2015-12-09 19:54:35 +09:00

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3.3 KiB
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/*=============================================================================
Copyright (c) 2011-2015 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_DETAIL_INT_HPP
#define SPROUT_DETAIL_INT_HPP
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/type_traits/enabler_if.hpp>
#include <sprout/type_traits/is_sint.hpp>
#include <sprout/type_traits/is_uint.hpp>
namespace sprout {
namespace detail {
//
// int_digits_mf
//
template<typename IntType, IntType Val, int Base = 10, bool = Val != 0>
struct int_digits_mf_impl;
template<typename IntType, IntType Val, int Base>
struct int_digits_mf_impl<IntType, Val, Base, false>
: public sprout::integral_constant<IntType, 0>
{};
template<typename IntType, IntType Val, int Base>
struct int_digits_mf_impl<IntType, Val, Base, true>
: public sprout::integral_constant<IntType, 1 + sprout::detail::int_digits_mf_impl<IntType, Val / Base, Base>::value>
{};
template<typename IntType, IntType Val, int Base = 10, bool = Val != 0>
struct int_digits_mf;
template<typename IntType, IntType Val, int Base>
struct int_digits_mf<IntType, Val, Base, false>
: public sprout::integral_constant<IntType, 1>
{};
template<typename IntType, IntType Val, int Base>
struct int_digits_mf<IntType, Val, Base, true>
: public sprout::integral_constant<IntType, 1 + sprout::detail::int_digits_mf_impl<IntType, Val / Base, Base>::value>
{};
//
// int_pow
//
template<
typename IntType, int Base = 10,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR IntType
int_pow(int exponent) {
return exponent ? Base * sprout::detail::int_pow<IntType, Base>(exponent - 1)
: 1
;
}
//
// int_digits
//
template<int Base = 10, typename IntType>
inline SPROUT_CONSTEXPR int
int_digits_impl(IntType val) {
return val ? 1 + sprout::detail::int_digits_impl<Base>(val / Base)
: 0
;
}
template<
int Base = 10, typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR int
int_digits(IntType val) {
return val ? 1 + sprout::detail::int_digits_impl<Base>(val / Base)
: 1
;
}
//
// int_digit_at
//
template<
int Base = 10, typename IntType,
typename sprout::enabler_if<sprout::is_sint<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR int
int_digit_at(IntType val, int digits) {
return val < 0 ? -((val / sprout::detail::int_pow<IntType, Base>(digits)) % Base)
: (val / sprout::detail::int_pow<IntType, Base>(digits)) % Base
;
}
template<
int Base = 10, typename IntType,
typename sprout::enabler_if<sprout::is_uint<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR int
int_digit_at(IntType val, int digits) {
return (val / sprout::detail::int_pow<IntType, Base>(digits)) % Base;
}
} // namespace detail
} // namespace sprout
#endif // #ifndef SPROUT_DETAIL_INT_HPP