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Sprout/sprout/index_tuple/index_n.hpp
2013-01-25 15:14:29 +09:00

77 lines
2.1 KiB
C++

#ifndef SPROUT_INDEX_TUPLE_INDEX_N_HPP
#define SPROUT_INDEX_TUPLE_INDEX_N_HPP
#include <cstddef>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/index_tuple/index_tuple.hpp>
#include <sprout/index_tuple/detail/make_indexes_helper.hpp>
namespace sprout {
//
// index_n
//
namespace detail {
template<typename IndexTuple>
struct index_n_next;
template<sprout::index_t... Indexes>
struct index_n_next<sprout::index_tuple<Indexes...>> {
public:
typedef sprout::index_tuple<Indexes..., Indexes...> type;
};
template<typename IndexTuple, sprout::index_t Tail>
struct index_n_next2;
template<sprout::index_t... Indexes, sprout::index_t Tail>
struct index_n_next2<sprout::index_tuple<Indexes...>, Tail> {
public:
typedef sprout::index_tuple<Indexes..., Indexes..., Tail> type;
};
template<sprout::index_t I, std::size_t N, typename Enable = void>
struct index_n_impl;
template<sprout::index_t I, std::size_t N>
struct index_n_impl<
I, N,
typename std::enable_if<(N == 0)>::type
> {
public:
typedef sprout::index_tuple<> type;
};
template<sprout::index_t I, std::size_t N>
struct index_n_impl<
I, N,
typename std::enable_if<(N == 1)>::type
> {
public:
typedef sprout::index_tuple<I> type;
};
template<sprout::index_t I, std::size_t N>
struct index_n_impl<
I, N,
typename std::enable_if<(N > 1 && N % 2 == 0)>::type
>
: public sprout::detail::index_n_next<
typename sprout::detail::index_n_impl<I, N / 2>::type
>
{};
template<sprout::index_t I, std::size_t N>
struct index_n_impl<
I, N,
typename std::enable_if<(N > 1 && N % 2 == 1)>::type
>
: public sprout::detail::index_n_next2<
typename sprout::detail::index_n_impl<I, N / 2>::type,
I
>
{};
} // namespace detail
template<sprout::index_t I, std::size_t N>
struct index_n
: public sprout::detail::make_indexes_helper<
sprout::detail::index_n_impl<I, N>
>
{};
} // namespace sprout
#endif // #ifndef SPROUT_INDEX_TUPLE_INDEX_N_HPP