| [/ |
| / Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com) |
| / |
| / Distributed under the Boost Software License, Version 1.0. (See accompanying |
| / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| /] |
| |
| [section:Sender Sender concepts] |
| |
| [heading sender and sender_to] |
| |
| template<class S> |
| concept sender = |
| move_constructible<remove_cvref_t<S>> && |
| !requires { |
| typename sender_traits<remove_cvref_t<S>>::__unspecialized; // exposition only |
| }; |
| |
| template<class S, class R> |
| concept sender_to = |
| sender<S> && |
| receiver<R> && |
| requires (S&& s, R&& r) { |
| execution::connect((S&&) s, (R&&) r); |
| }; |
| |
| None of these operations shall introduce data races as a result of concurrent |
| invocations of those functions from different threads. |
| |
| A sender type's destructor shall not block pending completion of the submitted |
| function objects. |
| |
| [inline_note The ability to wait for completion of submitted function objects |
| may be provided by the associated execution context.] |
| |
| [heading typed_sender] |
| |
| A sender is [*typed] if it declares what types it sends through a receiver's |
| channels. The `typed_sender` concept is defined as: |
| |
| template<template<template<class...> class Tuple, template<class...> class Variant> class> |
| struct has-value-types; // exposition only |
| |
| template<template<class...> class Variant> |
| struct has-error-types; // exposition only |
| |
| template<class S> |
| concept has-sender-types = // exposition only |
| requires { |
| typename has-value-types<S::template value_types>; |
| typename has-error-types<S::template error_types>; |
| typename bool_constant<S::sends_done>; |
| }; |
| |
| template<class S> |
| concept typed_sender = |
| sender<S> && |
| has-sender-types<sender_traits<remove_cvref_t<S>>>; |
| |
| [endsect] |
