make_opstate.hpp

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#ifndef KOKKOS_EXECUTION_IMPL_MAKE_OPSTATE_HPP
#define KOKKOS_EXECUTION_IMPL_MAKE_OPSTATE_HPP
 
#include "kokkos-execution/stdexec.hpp"
 
#include "kokkos-execution/impl/sender_concepts.hpp"
 
namespace Kokkos::Execution::Impl {
 
template <typename DomainType, template <typename...> typename OpStateType>
struct MakeOpState {
 
    template <typename Sndr, typename Rcvr, typename... Clsrs>
    struct Huddle {
        using type = OpStateType<Sndr, Rcvr, Clsrs...>;
 
        // NOLINTNEXTLINE(cppcoreguidelines-rvalue-reference-param-not-moved)
        constexpr auto operator()(Sndr&& sndr, Rcvr rcvr, Clsrs... clsrs) const
            noexcept(std::is_nothrow_constructible_v<type, Sndr&&, Rcvr&&, Clsrs&&...>) -> type {
            return type(std::forward<Sndr>(sndr), std::move(rcvr), std::move(clsrs)...);
        }
    };
 
    template <Impl::dispatching_sender Sndr, typename Rcvr, typename... Clsrs>
    struct Huddle<Sndr, Rcvr, Clsrs...> {
        using child_of_sndr_t = stdexec::__child_of<Sndr>;
        using clsr_of_sndr_t = typename stdexec::transform_sender_result_t<Sndr, stdexec::env_of_t<Rcvr>>::closure_t;
 
        using huddle_fn_t = Huddle<child_of_sndr_t, Rcvr, clsr_of_sndr_t, Clsrs...>;
        using type = typename huddle_fn_t::type;
 
        static constexpr bool sndr_has_nothrow_transform_sender = stdexec::__detail::__has_nothrow_transform_sender<
            DomainType,
            stdexec::set_value_t,
            Sndr&&,
            stdexec::env_of_t<Rcvr>
        >;
 
        static constexpr bool is_nothrow_huddle =
            std::is_nothrow_invocable_v<huddle_fn_t, child_of_sndr_t&&, Rcvr&&, clsr_of_sndr_t&&, Clsrs&&...>;

        // NOLINTNEXTLINE(cppcoreguidelines-rvalue-reference-param-not-moved)
        constexpr auto operator()(Sndr&& sndr, Rcvr&& rcvr, Clsrs... clsrs) const
            noexcept(sndr_has_nothrow_transform_sender && is_nothrow_huddle) -> type {
            auto trnsfrmd_sndr = stdexec::transform_sender(std::forward<Sndr>(sndr), stdexec::get_env(rcvr));
            return huddle_fn_t{}(
                stdexec::__forward_like<Sndr>(trnsfrmd_sndr.sndr),
                std::forward<Rcvr>(rcvr),
                std::move(trnsfrmd_sndr.clsr),
                std::move(clsrs)...);
        }
    };
};
 
} // namespace Kokkos::Execution::Impl
 
#endif // KOKKOS_EXECUTION_IMPL_MAKE_OPSTATE_HPP