#include <cstddef>
#include <cstdlib>
#include <iostream>
#include <string>

namespace
{
    namespace detail
    {
        template<typename>
        struct is_aggregated_type_available_helper
        {
            typedef void type;
        };
    }

    template<typename T, typename enable = void >
    struct is_aggregated_type_available
    {
        enum
        {
            value = false
        };
    };

    template<typename T>
    struct is_aggregated_type_available<
        T,
        typename detail::is_aggregated_type_available_helper<typename T::aggregated_type>::type >
    {
        enum
        {
            value = true
        };
    };
}

namespace
{
    struct x
    {
        typedef std::string aggregated_type;
    };

    struct y
    {
    };
}

int main(int, char*)
{
    std::cout << is_aggregated_type_available<x>::value << std::endl;
    std::cout << is_aggregated_type_available<y>::value << std::endl;
}