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https://github.com/bolero-MURAKAMI/Sprout.git
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74 lines
2 KiB
C++
74 lines
2 KiB
C++
#ifndef SPROUT_UTILITY_PACK_HPP
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#define SPROUT_UTILITY_PACK_HPP
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#include <cstddef>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/utility/forward.hpp>
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#include <sprout/type_traits/enabler_if.hpp>
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namespace sprout {
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//
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// tppack_at
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//
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namespace detail {
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template<std::size_t N, typename Head, typename... Tail>
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struct tppack_at_impl_1 {
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public:
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typedef typename sprout::detail::tppack_at_impl_1<N - 1, Tail...>::type type;
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};
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template<typename Head, typename... Tail>
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struct tppack_at_impl_1<0, Head, Tail...> {
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public:
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typedef Head type;
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};
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template<
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std::size_t N,
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typename... Args
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>
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struct tppack_at_impl
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: public sprout::detail::tppack_at_impl_1<N, Args...>
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{
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static_assert(N < sizeof...(Args), "N < sizeof...(Args)");
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};
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} // namespace detail
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template<std::size_t N, typename... Args>
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struct tppack_at
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: public sprout::detail::tppack_at_impl<N, Args...>
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{};
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//
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// fppack_at
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//
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namespace detail {
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template<
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std::size_t N,
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typename R,
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typename Head,
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typename... Tail,
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typename sprout::enabler_if<N == 0>::type = sprout::enabler
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>
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inline SPROUT_CONSTEXPR R fppack_at_impl(Head&& head, Tail&&... tail) {
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return sprout::forward<Head>(head);
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}
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template<
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std::size_t N,
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typename R,
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typename Head,
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typename... Tail,
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typename sprout::enabler_if<N != 0>::type = sprout::enabler
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>
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inline SPROUT_CONSTEXPR R fppack_at_impl(Head&& head, Tail&&... tail) {
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return sprout::detail::fppack_at_impl<N - 1, R>(sprout::forward<Tail>(tail)...);
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}
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} // namespace detail
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template<std::size_t N, typename... Args>
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inline SPROUT_CONSTEXPR typename sprout::tppack_at<N, Args&&...>::type fppack_at(Args&&... args) {
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return sprout::detail::fppack_at_impl<
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N,
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typename sprout::tppack_at<N, Args&&...>::type
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>(sprout::forward<Args>(args)...);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_UTILITY_PACK_HPP
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