template <class T> struct tuple_size;
Remarks: All specializations of tuple_size<T> shall meet the UnaryTypeTrait requirements ([meta.rqmts]) with a BaseCharacteristic of integral_constant<size_t, N> for some N.
template <class... Types>
class tuple_size<tuple<Types...> >
: public integral_constant<size_t, sizeof...(Types)> { };
template <size_t I, class... Types>
class tuple_element<I, tuple<Types...> > {
public:
typedef TI type;
};
Requires: I < sizeof...(Types). The program is ill-formed if I is out of bounds.
Type: TI is the type of the Ith element of Types, where indexing is zero-based.
template <class T> class tuple_size<const T>;
template <class T> class tuple_size<volatile T>;
template <class T> class tuple_size<const volatile T>;
Let TS denote tuple_size<T> of the cv-unqualified type T. Then each of the three templates shall meet the UnaryTypeTrait requirements ([meta.rqmts]) with a BaseCharacteristic of
integral_constant<size_t, TS::value>
template <size_t I, class T> class tuple_element<I, const T>;
template <size_t I, class T> class tuple_element<I, volatile T>;
template <size_t I, class T> class tuple_element<I, const volatile T>;
Let TE denote tuple_element<I, T> of the cv-unqualified type T. Then each of the three templates shall meet the TransformationTrait requirements ([meta.rqmts]) with a member typedef type that names the following type: