blob: 6398816fabbfaa335a721e2e6a73efc0a10e446c (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
|
//
// uses_executor.hpp
// ~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2018 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)
//
#ifndef BOOST_ASIO_USES_EXECUTOR_HPP
#define BOOST_ASIO_USES_EXECUTOR_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include <boost/asio/detail/config.hpp>
#include <boost/asio/detail/type_traits.hpp>
#include <boost/asio/detail/push_options.hpp>
namespace boost {
namespace asio {
/// A special type, similar to std::nothrow_t, used to disambiguate
/// constructors that accept executor arguments.
/**
* The executor_arg_t struct is an empty structure type used as a unique type
* to disambiguate constructor and function overloading. Specifically, some
* types have constructors with executor_arg_t as the first argument,
* immediately followed by an argument of a type that satisfies the Executor
* type requirements.
*/
struct executor_arg_t
{
/// Constructor.
BOOST_ASIO_CONSTEXPR executor_arg_t() BOOST_ASIO_NOEXCEPT
{
}
};
/// A special value, similar to std::nothrow, used to disambiguate constructors
/// that accept executor arguments.
/**
* See boost::asio::executor_arg_t and boost::asio::uses_executor
* for more information.
*/
#if defined(BOOST_ASIO_HAS_CONSTEXPR) || defined(GENERATING_DOCUMENTATION)
constexpr executor_arg_t executor_arg;
#elif defined(BOOST_ASIO_MSVC)
__declspec(selectany) executor_arg_t executor_arg;
#endif
/// The uses_executor trait detects whether a type T has an associated executor
/// that is convertible from type Executor.
/**
* Meets the BinaryTypeTrait requirements. The Asio library provides a
* definition that is derived from false_type. A program may specialize this
* template to derive from true_type for a user-defined type T that can be
* constructed with an executor, where the first argument of a constructor has
* type executor_arg_t and the second argument is convertible from type
* Executor.
*/
template <typename T, typename Executor>
struct uses_executor : false_type {};
} // namespace asio
} // namespace boost
#include <boost/asio/detail/pop_options.hpp>
#endif // BOOST_ASIO_USES_EXECUTOR_HPP
|
