projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| b32b8144 FG |
1 | // |
| 2 | // uses_executor.hpp | |
| 3 | // ~~~~~~~~~~~~~~~~~ | |
| 4 | // | |
| 92f5a8d4 | 5 | // Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com) |
| b32b8144 FG |
6 | // |
| 7 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
| 8 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
| 9 | // | |
| 10 | ||
| 11 | #ifndef BOOST_ASIO_USES_EXECUTOR_HPP | |
| 12 | #define BOOST_ASIO_USES_EXECUTOR_HPP | |
| 13 | ||
| 14 | #if defined(_MSC_VER) && (_MSC_VER >= 1200) | |
| 15 | # pragma once | |
| 16 | #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) | |
| 17 | ||
| 18 | #include <boost/asio/detail/config.hpp> | |
| 19 | #include <boost/asio/detail/type_traits.hpp> | |
| 20 | ||
| 21 | #include <boost/asio/detail/push_options.hpp> | |
| 22 | ||
| 23 | namespace boost { | |
| 24 | namespace asio { | |
| 25 | ||
| 26 | /// A special type, similar to std::nothrow_t, used to disambiguate | |
| 27 | /// constructors that accept executor arguments. | |
| 28 | /** | |
| 29 | * The executor_arg_t struct is an empty structure type used as a unique type | |
| 30 | * to disambiguate constructor and function overloading. Specifically, some | |
| 31 | * types have constructors with executor_arg_t as the first argument, | |
| 32 | * immediately followed by an argument of a type that satisfies the Executor | |
| 33 | * type requirements. | |
| 34 | */ | |
| 35 | struct executor_arg_t | |
| 36 | { | |
| 37 | /// Constructor. | |
| 38 | BOOST_ASIO_CONSTEXPR executor_arg_t() BOOST_ASIO_NOEXCEPT | |
| 39 | { | |
| 40 | } | |
| 41 | }; | |
| 42 | ||
| 43 | /// A special value, similar to std::nothrow, used to disambiguate constructors | |
| 44 | /// that accept executor arguments. | |
| 45 | /** | |
| 46 | * See boost::asio::executor_arg_t and boost::asio::uses_executor | |
| 47 | * for more information. | |
| 48 | */ | |
| 49 | #if defined(BOOST_ASIO_HAS_CONSTEXPR) || defined(GENERATING_DOCUMENTATION) | |
| 50 | constexpr executor_arg_t executor_arg; | |
| 51 | #elif defined(BOOST_ASIO_MSVC) | |
| 52 | __declspec(selectany) executor_arg_t executor_arg; | |
| 53 | #endif | |
| 54 | ||
| 55 | /// The uses_executor trait detects whether a type T has an associated executor | |
| 56 | /// that is convertible from type Executor. | |
| 57 | /** | |
| 58 | * Meets the BinaryTypeTrait requirements. The Asio library provides a | |
| 59 | * definition that is derived from false_type. A program may specialize this | |
| 60 | * template to derive from true_type for a user-defined type T that can be | |
| 61 | * constructed with an executor, where the first argument of a constructor has | |
| 62 | * type executor_arg_t and the second argument is convertible from type | |
| 63 | * Executor. | |
| 64 | */ | |
| 65 | template <typename T, typename Executor> | |
| 66 | struct uses_executor : false_type {}; | |
| 67 | ||
| 68 | } // namespace asio | |
| 69 | } // namespace boost | |
| 70 | ||
| 71 | #include <boost/asio/detail/pop_options.hpp> | |
| 72 | ||
| 73 | #endif // BOOST_ASIO_USES_EXECUTOR_HPP |