5 // Copyright (c) 2003-2017 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>
24 #include <boost/asio/detail/memory.hpp>
26 #include <boost/asio/detail/push_options.hpp>
32 // Completion handler to adapt a promise as a completion handler.
37 // Construct from use_future special value.
38 template <typename Alloc>
39 promise_handler(use_future_t<Alloc> uf)
40 : promise_(std::allocate_shared<std::promise<T> >(
41 BOOST_ASIO_REBIND_ALLOC(Alloc, char)(uf.get_allocator()),
43 BOOST_ASIO_REBIND_ALLOC(Alloc, char)(uf.get_allocator())))
49 promise_->set_value(t);
52 void operator()(const boost::system::error_code& ec, T t)
55 promise_->set_exception(
56 std::make_exception_ptr(
57 boost::system::system_error(ec)));
59 promise_->set_value(t);
63 std::shared_ptr<std::promise<T> > promise_;
66 // Completion handler to adapt a void promise as a completion handler.
68 class promise_handler<void>
71 // Construct from use_future special value. Used during rebinding.
72 template <typename Alloc>
73 promise_handler(use_future_t<Alloc> uf)
74 : promise_(std::allocate_shared<std::promise<void> >(
75 BOOST_ASIO_REBIND_ALLOC(Alloc, char)(uf.get_allocator()),
77 BOOST_ASIO_REBIND_ALLOC(Alloc, char)(uf.get_allocator())))
83 promise_->set_value();
86 void operator()(const boost::system::error_code& ec)
89 promise_->set_exception(
90 std::make_exception_ptr(
91 boost::system::system_error(ec)));
93 promise_->set_value();
97 std::shared_ptr<std::promise<void> > promise_;
100 // Ensure any exceptions thrown from the handler are propagated back to the
101 // caller via the future.
102 template <typename Function, typename T>
103 void asio_handler_invoke(Function f, promise_handler<T>* h)
105 std::shared_ptr<std::promise<T> > p(h->promise_);
112 p->set_exception(std::current_exception());
116 } // namespace detail
118 #if !defined(GENERATING_DOCUMENTATION)
120 // Handler traits specialisation for promise_handler.
121 template <typename T>
122 class async_result<detail::promise_handler<T> >
125 // The initiating function will return a future.
126 typedef std::future<T> type;
128 // Constructor creates a new promise for the async operation, and obtains the
129 // corresponding future.
130 explicit async_result(detail::promise_handler<T>& h)
132 value_ = h.promise_->get_future();
135 // Obtain the future to be returned from the initiating function.
136 type get() { return std::move(value_); }
142 // Handler type specialisation for use_future.
143 template <typename Allocator, typename ReturnType>
144 struct handler_type<use_future_t<Allocator>, ReturnType()>
146 typedef detail::promise_handler<void> type;
149 // Handler type specialisation for use_future.
150 template <typename Allocator, typename ReturnType, typename Arg1>
151 struct handler_type<use_future_t<Allocator>, ReturnType(Arg1)>
153 typedef detail::promise_handler<Arg1> type;
156 // Handler type specialisation for use_future.
157 template <typename Allocator, typename ReturnType>
158 struct handler_type<use_future_t<Allocator>,
159 ReturnType(boost::system::error_code)>
161 typedef detail::promise_handler<void> type;
164 // Handler type specialisation for use_future.
165 template <typename Allocator, typename ReturnType, typename Arg2>
166 struct handler_type<use_future_t<Allocator>,
167 ReturnType(boost::system::error_code, Arg2)>
169 typedef detail::promise_handler<Arg2> type;
172 #endif // !defined(GENERATING_DOCUMENTATION)
177 #include <boost/asio/detail/pop_options.hpp>
179 #endif // BOOST_ASIO_IMPL_USE_FUTURE_HPP