型リストを逆順にするメタ関数です。
template <int N, class Seq> struct reverse_impl; template <int N, class Head, class... Tail> struct reverse_impl<N, tuple<Head, Tail...>> { typedef typename concat<typename reverse_impl<N-1, tuple<Tail...>>::type, tuple<Head> >::type type; }; template <class... Seq> struct reverse_impl<0, tuple<Seq...>> { typedef tuple<Seq...> type; }; template <class Seq> struct reverse; template <class... Seq> struct reverse<tuple<Seq...>> { typedef typename reverse_impl<sizeof...(Seq), tuple<Seq...>>::type type; };
reverse<tuple<int, double, long>>::type → tuple<long, double, int>
