static auto on()

in Source/Shared/arcana/scheduling/state_machine.h [255:292]

• 29 lines of code
• 2 McCabe index (conditional complexity)

            static auto on(state_machine_driver& driver,
                           state_machine_state<ResultT>& state,
                           DispatcherT& dispatcher,
                           cancellation& cancel,
                           CallableT&& callable)
            {
                struct pending_data
                {
                    ResultT data{};
                };

                auto node_data = std::make_shared<pending_data>();

                ResultT* dataptr = &node_data->data;

                using callable_traits = internal::callable_traits<CallableT, ResultT>;
                static_assert(std::is_same_v<typename callable_traits::error_propagation_type, std::error_code>, "state machine only supports error_codes for now");

                auto work = [ callable = std::forward<CallableT>(callable), dataptr ]() noexcept
                {
                    return callable(*dataptr);
                };

                return driver.enter(state, cancel)
                    .then(dispatcher, cancel, std::move(work))
                    .then(inline_scheduler,
                          cancellation::none(),
                          [&, node_data = std::move(node_data) ](const typename callable_traits::expected_return_type& result) mutable noexcept {
                              ResultT data = std::move(node_data->data);
                              // remove ourselves as a cancellation listener, as we were
                              // only listening in order to avoid getting stuck on enter.
                              node_data.reset();

                              driver.exit(state, data);

                              return result;
                          });
            }