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1 | // |
2 | // Copyright (c) 2016-2017 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 | // Official repository: https://github.com/boostorg/beast | |
8 | // | |
9 | ||
10 | #ifndef BOOST_BEAST_BIND_HANDLER_HPP | |
11 | #define BOOST_BEAST_BIND_HANDLER_HPP | |
12 | ||
13 | #include <boost/beast/core/detail/config.hpp> | |
14 | #include <boost/beast/core/type_traits.hpp> | |
15 | #include <boost/beast/core/detail/bind_handler.hpp> | |
16 | #include <type_traits> | |
17 | #include <utility> | |
18 | ||
19 | namespace boost { | |
20 | namespace beast { | |
21 | ||
22 | /** Bind parameters to a completion handler, creating a new handler. | |
23 | ||
24 | This function creates a new handler which, when invoked, calls | |
25 | the original handler with the list of bound arguments. Any | |
26 | parameters passed in the invocation will be subtituted for | |
27 | placeholders present in the list of bound arguments. Parameters | |
28 | which are not matched to placeholders are silently discarded. | |
29 | The passed handler and arguments are forwarded into the returned | |
30 | handler, which provides the same `io_context` execution guarantees | |
31 | as the original handler. | |
32 | ||
33 | Unlike `boost::asio::io_context::wrap`, the returned handler can | |
34 | be used in a subsequent call to `boost::asio::io_context::post` | |
35 | instead of `boost::asio::io_context::dispatch`, to ensure that | |
36 | the handler will not be invoked immediately by the calling | |
37 | function. | |
38 | ||
39 | Example: | |
40 | ||
41 | @code | |
42 | template<class AsyncReadStream, class ReadHandler> | |
43 | void | |
44 | signal_aborted(AsyncReadStream& stream, ReadHandler&& handler) | |
45 | { | |
46 | boost::asio::post( | |
47 | stream.get_executor(), | |
48 | bind_handler(std::forward<ReadHandler>(handler), | |
49 | boost::asio::error::operation_aborted, 0)); | |
50 | } | |
51 | @endcode | |
52 | ||
53 | @param handler The handler to wrap. | |
54 | ||
55 | @param args A list of arguments to bind to the handler. The | |
56 | arguments are forwarded into the returned object. | |
57 | */ | |
58 | template<class Handler, class... Args> | |
59 | #if BOOST_BEAST_DOXYGEN | |
60 | implementation_defined | |
61 | #else | |
62 | detail::bound_handler< | |
63 | typename std::decay<Handler>::type, Args...> | |
64 | #endif | |
65 | bind_handler(Handler&& handler, Args&&... args) | |
66 | { | |
67 | #if 0 | |
68 | static_assert(is_completion_handler< | |
69 | Handler, void(Args...)>::value, | |
70 | "Handler requirements not met"); | |
71 | #endif | |
72 | return detail::bound_handler<typename std::decay< | |
73 | Handler>::type, Args...>(std::forward< | |
74 | Handler>(handler), std::forward<Args>(args)...); | |
75 | } | |
76 | ||
77 | } // beast | |
78 | } // boost | |
79 | ||
80 | #endif |