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- //
- // defer.hpp
- // ~~~~~~~~~
- //
- // Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- //
- // Distributed under the Boost Software License, Version 1.0. (See accompanying
- // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- //
-
- #ifndef ASIO_DEFER_HPP
- #define ASIO_DEFER_HPP
-
- #if defined(_MSC_VER) && (_MSC_VER >= 1200)
- # pragma once
- #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
-
- #include "asio/detail/config.hpp"
- #include "asio/async_result.hpp"
- #include "asio/detail/type_traits.hpp"
- #include "asio/execution_context.hpp"
- #include "asio/is_executor.hpp"
-
- #include "asio/detail/push_options.hpp"
-
- namespace asio {
-
- /// Submits a completion token or function object for execution.
- /**
- * This function submits an object for execution using the object's associated
- * executor. The function object is queued for execution, and is never called
- * from the current thread prior to returning from <tt>defer()</tt>.
- *
- * The use of @c defer(), rather than @ref post(), indicates the caller's
- * preference that the executor defer the queueing of the function object. This
- * may allow the executor to optimise queueing for cases when the function
- * object represents a continuation of the current call context.
- *
- * This function has the following effects:
- *
- * @li Constructs a function object handler of type @c Handler, initialized
- * with <tt>handler(forward<CompletionToken>(token))</tt>.
- *
- * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
- * initializing the object as <tt>result(handler)</tt>.
- *
- * @li Obtains the handler's associated executor object @c ex by performing
- * <tt>get_associated_executor(handler)</tt>.
- *
- * @li Obtains the handler's associated allocator object @c alloc by performing
- * <tt>get_associated_allocator(handler)</tt>.
- *
- * @li Performs <tt>ex.defer(std::move(handler), alloc)</tt>.
- *
- * @li Returns <tt>result.get()</tt>.
- */
- template <typename CompletionToken>
- ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) defer(
- ASIO_MOVE_ARG(CompletionToken) token);
-
- /// Submits a completion token or function object for execution.
- /**
- * This function submits an object for execution using the specified executor.
- * The function object is queued for execution, and is never called from the
- * current thread prior to returning from <tt>defer()</tt>.
- *
- * The use of @c defer(), rather than @ref post(), indicates the caller's
- * preference that the executor defer the queueing of the function object. This
- * may allow the executor to optimise queueing for cases when the function
- * object represents a continuation of the current call context.
- *
- * This function has the following effects:
- *
- * @li Constructs a function object handler of type @c Handler, initialized
- * with <tt>handler(forward<CompletionToken>(token))</tt>.
- *
- * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
- * initializing the object as <tt>result(handler)</tt>.
- *
- * @li Obtains the handler's associated executor object @c ex1 by performing
- * <tt>get_associated_executor(handler)</tt>.
- *
- * @li Creates a work object @c w by performing <tt>make_work(ex1)</tt>.
- *
- * @li Obtains the handler's associated allocator object @c alloc by performing
- * <tt>get_associated_allocator(handler)</tt>.
- *
- * @li Constructs a function object @c f with a function call operator that
- * performs <tt>ex1.dispatch(std::move(handler), alloc)</tt> followed by
- * <tt>w.reset()</tt>.
- *
- * @li Performs <tt>Executor(ex).defer(std::move(f), alloc)</tt>.
- *
- * @li Returns <tt>result.get()</tt>.
- */
- template <typename Executor, typename CompletionToken>
- ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) defer(
- const Executor& ex, ASIO_MOVE_ARG(CompletionToken) token,
- typename enable_if<is_executor<Executor>::value>::type* = 0);
-
- /// Submits a completion token or function object for execution.
- /**
- * @returns <tt>defer(ctx.get_executor(), forward<CompletionToken>(token))</tt>.
- */
- template <typename ExecutionContext, typename CompletionToken>
- ASIO_INITFN_RESULT_TYPE(CompletionToken, void()) defer(
- ExecutionContext& ctx, ASIO_MOVE_ARG(CompletionToken) token,
- typename enable_if<is_convertible<
- ExecutionContext&, execution_context&>::value>::type* = 0);
-
- } // namespace asio
-
- #include "asio/detail/pop_options.hpp"
-
- #include "asio/impl/defer.hpp"
-
- #endif // ASIO_DEFER_HPP
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