HPX_HOST_DEVICE HPX_FORCEINLINE std::pair< typename hpx::util::tuple_element< 0, typename Iter::iterator_tuple_type >::type, typename hpx::util::tuple_element< 1, typename Iter::iterator_tuple_type >::type > operator()(Iter part_begin, std::size_t part_size, std::size_t /*part_index*/) { auto iters = part_begin.get_iterator_tuple(); return util::transform_loop_n(policy_, hpx::util::get<0>(iters), part_size, hpx::util::get<1>(iters), transform_projected<F, Proj>{f_, proj_}); }