gistfile1.txt

template<class T, class = void>
struct is_buffers_generator
    : std::false_type
{
};

template<class T, class = void>
struct is_buffers_generator<T, detail::void_t<
    std::is_constructible<
        typename T::const_buffers_type, decltype(
        std::declval<T&>().prepare(
            std::declval<error_code&>()))>,
    std::declval<T&>().consume(
        std::declval<std::size_t>())>
    > : std::true_type
{
};

/** A buffer sequence generator.
*/
struct BuffersGenerator
{
    using const_buffers_type = __implementation_defined__;

    const_buffers_type prepare( error_code& ec );
    void consume( std::size_t n );
};