Sprout/sprout/detail/param_at.hpp
2016-02-25 18:48:28 +09:00

53 lines
1.8 KiB
C++

/*=============================================================================
Copyright (c) 2011-2016 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_PARAM_AT_HPP
#define SPROUT_DETAIL_PARAM_AT_HPP
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/workaround/std/cstddef.hpp>
namespace sprout {
namespace detail {
template<typename R, typename T, typename... Values>
inline SPROUT_CONSTEXPR typename std::enable_if<
sizeof...(Values) == 0,
R
>::type
param_at(std::size_t, T const& v, Values const&...) {
return v;
}
template<typename R, typename T, typename... Values>
inline SPROUT_CONSTEXPR typename std::enable_if<
sizeof...(Values) != 0,
R
>::type
param_at(std::size_t n, T const& v, Values const&... values) {
return n == 0 ? v : sprout::detail::param_at<R>(n - 1, values...);
}
template<typename R, typename T, typename... Values>
inline SPROUT_CONSTEXPR typename std::enable_if<
sizeof...(Values) == 0,
R
>::type
param_seq_at(std::size_t, std::size_t m, T const& v, Values const&...) {
return v[m];
}
template<typename R, typename T, typename... Values>
inline SPROUT_CONSTEXPR typename std::enable_if<
sizeof...(Values) != 0,
R
>::type
param_seq_at(std::size_t n, std::size_t m, T const& v, Values const&... values) {
return n == 0 ? v[m] : sprout::detail::param_seq_at<R>(n - 1, m, values...);
}
} // namespace detail
} // namespace sprout
#endif // #ifndef SPROUT_DETAIL_PARAM_AT_HPP