137 lines
4.2 KiB
C++
137 lines
4.2 KiB
C++
//
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// compose.hpp
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// ~~~~~~~~~~~
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//
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// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef ASIO_COMPOSE_HPP
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#define ASIO_COMPOSE_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
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#include "asio/detail/config.hpp"
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#include "asio/async_result.hpp"
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#include "asio/detail/push_options.hpp"
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namespace asio {
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#if defined(ASIO_HAS_VARIADIC_TEMPLATES) \
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|| defined(GENERATING_DOCUMENTATION)
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/// Launch an asynchronous operation with a stateful implementation.
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/**
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* The async_compose function simplifies the implementation of composed
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* asynchronous operations automatically wrapping a stateful function object
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* with a conforming intermediate completion handler.
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*
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* @param implementation A function object that contains the implementation of
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* the composed asynchronous operation. The first argument to the function
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* object is a non-const reference to the enclosing intermediate completion
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* handler. The remaining arguments are any arguments that originate from the
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* completion handlers of any asynchronous operations performed by the
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* implementation.
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* @param token The completion token.
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*
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* @param io_objects_or_executors Zero or more I/O objects or I/O executors for
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* which outstanding work must be maintained.
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*
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* @par Example:
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*
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* @code struct async_echo_implementation
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* {
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* tcp::socket& socket_;
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* asio::mutable_buffer buffer_;
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* enum { starting, reading, writing } state_;
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*
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* template <typename Self>
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* void operator()(Self& self,
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* asio::error_code error = {},
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* std::size_t n = 0)
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* {
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* switch (state_)
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* {
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* case starting:
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* state_ = reading;
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* socket_.async_read_some(
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* buffer_, std::move(self));
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* break;
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* case reading:
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* if (error)
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* {
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* self.complete(error, 0);
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* }
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* else
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* {
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* state_ = writing;
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* asio::async_write(socket_, buffer_,
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* asio::transfer_exactly(n),
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* std::move(self));
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* }
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* break;
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* case writing:
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* self.complete(error, n);
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* break;
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* }
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* }
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* };
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*
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* template <typename CompletionToken>
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* auto async_echo(tcp::socket& socket,
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* asio::mutable_buffer buffer,
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* CompletionToken&& token) ->
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* typename asio::async_result<
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* typename std::decay<CompletionToken>::type,
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* void(asio::error_code, std::size_t)>::return_type
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* {
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* return asio::async_compose<CompletionToken,
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* void(asio::error_code, std::size_t)>(
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* async_echo_implementation{socket, buffer,
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* async_echo_implementation::starting},
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* token, socket);
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* } @endcode
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*/
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template <typename CompletionToken, typename Signature,
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typename Implementation, typename... IoObjectsOrExecutors>
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ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, Signature)
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async_compose(ASIO_MOVE_ARG(Implementation) implementation,
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ASIO_NONDEDUCED_MOVE_ARG(CompletionToken) token,
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ASIO_MOVE_ARG(IoObjectsOrExecutors)... io_objects_or_executors);
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#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
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// || defined(GENERATING_DOCUMENTATION)
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template <typename CompletionToken, typename Signature, typename Implementation>
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ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, Signature)
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async_compose(ASIO_MOVE_ARG(Implementation) implementation,
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ASIO_NONDEDUCED_MOVE_ARG(CompletionToken) token);
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#define ASIO_PRIVATE_ASYNC_COMPOSE_DEF(n) \
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template <typename CompletionToken, typename Signature, \
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typename Implementation, ASIO_VARIADIC_TPARAMS(n)> \
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ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, Signature) \
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async_compose(ASIO_MOVE_ARG(Implementation) implementation, \
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ASIO_NONDEDUCED_MOVE_ARG(CompletionToken) token, \
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ASIO_VARIADIC_MOVE_PARAMS(n));
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/**/
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ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_ASYNC_COMPOSE_DEF)
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#undef ASIO_PRIVATE_ASYNC_COMPOSE_DEF
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#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
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// || defined(GENERATING_DOCUMENTATION)
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} // namespace asio
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#include "asio/detail/pop_options.hpp"
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#include "asio/impl/compose.hpp"
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#endif // ASIO_COMPOSE_HPP
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