cxx/test/utilities/tuple/tuple.tuple/tuple.helper/tuple_size.pass.cpp

//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// <tuple>

// template <class... Types> class tuple;

// template <class... Types>
//   class tuple_size<tuple<Types...>>
//     : public integral_constant<size_t, sizeof...(Types)> { };

#include <tuple>
#include <type_traits>

template <class T, std::size_t N>
void test()
{
    static_assert((std::is_base_of<std::integral_constant<std::size_t, N>,
                                   std::tuple_size<T> >::value), "");
    static_assert((std::is_base_of<std::integral_constant<std::size_t, N>,
                                   std::tuple_size<const T> >::value), "");
    static_assert((std::is_base_of<std::integral_constant<std::size_t, N>,
                                   std::tuple_size<volatile T> >::value), "");
    static_assert((std::is_base_of<std::integral_constant<std::size_t, N>,
                                   std::tuple_size<const volatile T> >::value), "");
}

int main()
{
    test<std::tuple<>, 0>();
    test<std::tuple<int>, 1>();
    test<std::tuple<char, int>, 2>();
    test<std::tuple<char, char*, int>, 3>();
}