Function TupleRef

layers/external/parallel_hashmap/phmap.h:691–694

// ----------------------------------------------------------------------------
template <class T>
auto TupleRef(T&& t) -> decltype(TupleRefImpl(std::forward<T>(t),
                                              phmap::make_index_sequence<std::tuple_size<typename std::decay<T>::type>::value>())) {
    return TupleRefImpl(std::forward<T>(t), phmap::make_index_sequence<std::tuple_size<typename std::decay<T>::type>::value>());
}

template <class F, class K, class V>
decltype(std::declval<F>()(std::declval<const K&>(), std::piecewise_construct, std::declval<std::tuple<K>>(), std::declval<V>()))