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1 | // | |
2 | // Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com) | |
3 | // | |
4 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
5 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
6 | // | |
7 | ||
8 | #ifndef BEAST_BIND_HANDLER_HPP | |
9 | #define BEAST_BIND_HANDLER_HPP | |
10 | ||
11 | #include <beast/config.hpp> | |
12 | #include <beast/core/handler_concepts.hpp> | |
13 | #include <beast/core/detail/bind_handler.hpp> | |
14 | #include <type_traits> | |
15 | #include <utility> | |
16 | ||
17 | namespace beast { | |
18 | ||
19 | /** Bind parameters to a completion handler, creating a new handler. | |
20 | ||
21 | This function creates a new handler which, when invoked with no | |
22 | parameters, calls the original handler with the list of bound | |
23 | arguments. The passed handler and arguments are forwarded into | |
24 | the returned handler, which provides the same `io_service` | |
25 | execution guarantees as the original handler. | |
26 | ||
27 | Unlike `io_service::wrap`, the returned handler can be used in | |
28 | a subsequent call to `io_service::post` instead of | |
29 | `io_service::dispatch`, to ensure that the handler will not be | |
30 | invoked immediately by the calling function. | |
31 | ||
32 | Example: | |
33 | ||
34 | @code | |
35 | ||
36 | template<class AsyncReadStream, class ReadHandler> | |
37 | void | |
38 | do_cancel(AsyncReadStream& stream, ReadHandler&& handler) | |
39 | { | |
40 | stream.get_io_service().post( | |
41 | bind_handler(std::forward<ReadHandler>(handler), | |
42 | boost::asio::error::operation_aborted, 0)); | |
43 | } | |
44 | ||
45 | @endcode | |
46 | ||
47 | @param handler The handler to wrap. | |
48 | ||
49 | @param args A list of arguments to bind to the handler. The | |
50 | arguments are forwarded into the returned object. | |
51 | */ | |
52 | template<class Handler, class... Args> | |
53 | #if BEAST_DOXYGEN | |
54 | implementation_defined | |
55 | #else | |
56 | detail::bound_handler< | |
57 | typename std::decay<Handler>::type, Args...> | |
58 | #endif | |
59 | bind_handler(Handler&& handler, Args&&... args) | |
60 | { | |
61 | static_assert(is_CompletionHandler< | |
62 | Handler, void(Args...)>::value, | |
63 | "Handler requirements not met"); | |
64 | return detail::bound_handler<typename std::decay< | |
65 | Handler>::type, Args...>(std::forward< | |
66 | Handler>(handler), std::forward<Args>(args)...); | |
67 | } | |
68 | ||
69 | } // beast | |
70 | ||
71 | #endif |