5 // Copyright (c) 2003-2014 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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)
11 #ifndef BOOST_ASIO_IMPL_USE_FUTURE_HPP
12 #define BOOST_ASIO_IMPL_USE_FUTURE_HPP
14 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
16 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
18 #include <boost/asio/detail/config.hpp>
20 #include <boost/asio/async_result.hpp>
21 #include <boost/system/error_code.hpp>
22 #include <boost/asio/handler_type.hpp>
23 #include <boost/system/system_error.hpp>
25 #include <boost/asio/detail/push_options.hpp>
31 // Completion handler to adapt a promise as a completion handler.
36 // Construct from use_future special value.
37 template <typename Allocator>
38 promise_handler(use_future_t<Allocator> uf)
39 : promise_(std::allocate_shared<std::promise<T> >(
40 uf.get_allocator(), std::allocator_arg, uf.get_allocator()))
46 promise_->set_value(t);
49 void operator()(const boost::system::error_code& ec, T t)
52 promise_->set_exception(
53 std::make_exception_ptr(
54 boost::system::system_error(ec)));
56 promise_->set_value(t);
60 std::shared_ptr<std::promise<T> > promise_;
63 // Completion handler to adapt a void promise as a completion handler.
65 class promise_handler<void>
68 // Construct from use_future special value. Used during rebinding.
69 template <typename Allocator>
70 promise_handler(use_future_t<Allocator> uf)
71 : promise_(std::allocate_shared<std::promise<void> >(
72 uf.get_allocator(), std::allocator_arg, uf.get_allocator()))
78 promise_->set_value();
81 void operator()(const boost::system::error_code& ec)
84 promise_->set_exception(
85 std::make_exception_ptr(
86 boost::system::system_error(ec)));
88 promise_->set_value();
92 std::shared_ptr<std::promise<void> > promise_;
95 // Ensure any exceptions thrown from the handler are propagated back to the
96 // caller via the future.
97 template <typename Function, typename T>
98 void asio_handler_invoke(Function f, promise_handler<T>* h)
100 std::shared_ptr<std::promise<T> > p(h->promise_);
107 p->set_exception(std::current_exception());
111 } // namespace detail
113 #if !defined(GENERATING_DOCUMENTATION)
115 // Handler traits specialisation for promise_handler.
116 template <typename T>
117 class async_result<detail::promise_handler<T> >
120 // The initiating function will return a future.
121 typedef std::future<T> type;
123 // Constructor creates a new promise for the async operation, and obtains the
124 // corresponding future.
125 explicit async_result(detail::promise_handler<T>& h)
127 value_ = h.promise_->get_future();
130 // Obtain the future to be returned from the initiating function.
131 type get() { return std::move(value_); }
137 // Handler type specialisation for use_future.
138 template <typename Allocator, typename ReturnType>
139 struct handler_type<use_future_t<Allocator>, ReturnType()>
141 typedef detail::promise_handler<void> type;
144 // Handler type specialisation for use_future.
145 template <typename Allocator, typename ReturnType, typename Arg1>
146 struct handler_type<use_future_t<Allocator>, ReturnType(Arg1)>
148 typedef detail::promise_handler<Arg1> type;
151 // Handler type specialisation for use_future.
152 template <typename Allocator, typename ReturnType>
153 struct handler_type<use_future_t<Allocator>,
154 ReturnType(boost::system::error_code)>
156 typedef detail::promise_handler<void> type;
159 // Handler type specialisation for use_future.
160 template <typename Allocator, typename ReturnType, typename Arg2>
161 struct handler_type<use_future_t<Allocator>,
162 ReturnType(boost::system::error_code, Arg2)>
164 typedef detail::promise_handler<Arg2> type;
167 #endif // !defined(GENERATING_DOCUMENTATION)
172 #include <boost/asio/detail/pop_options.hpp>
174 #endif // BOOST_ASIO_IMPL_USE_FUTURE_HPP