// defer.hpp
// ~~~~~~~~~
//
-// Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+// Copyright (c) 2003-2022 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)
* 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:
+ * @param token The @ref completion_token that will be used to produce a
+ * completion handler. The function signature of the completion handler must be:
+ * @code void handler(); @endcode
*
- * @li Constructs a function object handler of type @c Handler, initialized
- * with <tt>handler(forward<CompletionToken>(token))</tt>.
+ * @returns This function returns <tt>async_initiate<NullaryToken,
+ * void()>(Init{}, token)</tt>, where @c Init is a function object type defined
+ * as:
*
- * @li Constructs an object @c result of type <tt>async_result<Handler></tt>,
- * initializing the object as <tt>result(handler)</tt>.
+ * @code class Init
+ * {
+ * public:
+ * template <typename CompletionHandler>
+ * void operator()(CompletionHandler&& completion_handler) const;
+ * }; @endcode
*
- * @li Obtains the handler's associated executor object @c ex by performing
- * <tt>get_associated_executor(handler)</tt>.
+ * The function call operator of @c Init:
*
- * @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 Obtains the handler's associated executor object @c ex of type @c Ex by
+ * performing @code auto ex = get_associated_executor(handler); @endcode
*
- * @li Returns <tt>result.get()</tt>.
+ * @li Obtains the handler's associated allocator object @c alloc by performing
+ * @code auto alloc = get_associated_allocator(handler); @endcode
+ *
+ * @li If <tt>execution::is_executor<Ex>::value</tt> is true, performs
+ * @code execution::execute(
+ * prefer(
+ * require(ex, execution::blocking.never),
+ * execution::relationship.continuation,
+ * execution::allocator(alloc)),
+ * std::forward<CompletionHandler>(completion_handler)); @endcode
+ *
+ * @li If <tt>execution::is_executor<Ex>::value</tt> is false, performs
+ * @code ex.defer(
+ * std::forward<CompletionHandler>(completion_handler),
+ * alloc); @endcode
+ *
+ * @par Completion Signature
+ * @code void() @endcode
*/
-template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) CompletionToken>
-BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, void()) defer(
- BOOST_ASIO_MOVE_ARG(CompletionToken) token);
+template <BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken>
+BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(NullaryToken, void()) defer(
+ BOOST_ASIO_MOVE_ARG(NullaryToken) token);
/// Submits a completion token or function object for execution.
/**
* 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>.
+ * @param ex The target executor.
*
- * @li Obtains the handler's associated executor object @c ex1 by performing
- * <tt>get_associated_executor(handler)</tt>.
+ * @param token The @ref completion_token that will be used to produce a
+ * completion handler. The function signature of the completion handler must be:
+ * @code void handler(); @endcode
*
- * @li Creates a work object @c w by performing <tt>make_work(ex1)</tt>.
+ * @returns This function returns <tt>async_initiate<NullaryToken,
+ * void()>(Init{ex}, token)</tt>, where @c Init is a function object type
+ * defined as:
*
- * @li Obtains the handler's associated allocator object @c alloc by performing
- * <tt>get_associated_allocator(handler)</tt>.
+ * @code class Init
+ * {
+ * public:
+ * using executor_type = Executor;
+ * explicit Init(const Executor& ex) : ex_(ex) {}
+ * executor_type get_executor() const noexcept { return ex_; }
+ * template <typename CompletionHandler>
+ * void operator()(CompletionHandler&& completion_handler) const;
+ * private:
+ * Executor ex_; // exposition only
+ * }; @endcode
*
- * @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>.
+ * The function call operator of @c Init:
*
- * @li Performs <tt>Executor(ex).defer(std::move(f), alloc)</tt>.
+ * @li Obtains the handler's associated executor object @c ex1 of type @c Ex1 by
+ * performing @code auto ex1 = get_associated_executor(handler, ex); @endcode
*
- * @li Returns <tt>result.get()</tt>.
+ * @li Obtains the handler's associated allocator object @c alloc by performing
+ * @code auto alloc = get_associated_allocator(handler); @endcode
+ *
+ * @li If <tt>execution::is_executor<Ex1>::value</tt> is true, constructs a
+ * function object @c f with a member @c executor_ that is initialised with
+ * <tt>prefer(ex1, execution::outstanding_work.tracked)</tt>, a member @c
+ * handler_ that is a decay-copy of @c completion_handler, and a function call
+ * operator that performs:
+ * @code auto a = get_associated_allocator(handler_);
+ * execution::execute(
+ * prefer(executor_,
+ * execution::blocking.possibly,
+ * execution::allocator(a)),
+ * std::move(handler_)); @endcode
+ *
+ * @li If <tt>execution::is_executor<Ex1>::value</tt> is false, constructs a
+ * function object @c f with a member @c work_ that is initialised with
+ * <tt>make_work_guard(ex1)</tt>, a member @c handler_ that is a decay-copy of
+ * @c completion_handler, and a function call operator that performs:
+ * @code auto a = get_associated_allocator(handler_);
+ * work_.get_executor().dispatch(std::move(handler_), a);
+ * work_.reset(); @endcode
+ *
+ * @li If <tt>execution::is_executor<Ex>::value</tt> is true, performs
+ * @code execution::execute(
+ * prefer(
+ * require(ex, execution::blocking.never),
+ * execution::relationship.continuation,
+ * execution::allocator(alloc)),
+ * std::move(f)); @endcode
+ *
+ * @li If <tt>execution::is_executor<Ex>::value</tt> is false, performs
+ * @code ex.defer(std::move(f), alloc); @endcode
+ *
+ * @par Completion Signature
+ * @code void() @endcode
*/
template <typename Executor,
- BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) CompletionToken
+ BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(Executor)>
-BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, void()) defer(
+BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(NullaryToken, void()) defer(
const Executor& ex,
- BOOST_ASIO_MOVE_ARG(CompletionToken) token
+ BOOST_ASIO_MOVE_ARG(NullaryToken) token
BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(Executor),
- typename enable_if<
+ typename constraint<
execution::is_executor<Executor>::value || is_executor<Executor>::value
- >::type* = 0);
+ >::type = 0);
/// Submits a completion token or function object for execution.
/**
- * @returns <tt>defer(ctx.get_executor(), forward<CompletionToken>(token))</tt>.
+ * @param ctx An execution context, from which the target executor is obtained.
+ *
+ * @param token The @ref completion_token that will be used to produce a
+ * completion handler. The function signature of the completion handler must be:
+ * @code void handler(); @endcode
+ *
+ * @returns <tt>defer(ctx.get_executor(), forward<NullaryToken>(token))</tt>.
+ *
+ * @par Completion Signature
+ * @code void() @endcode
*/
template <typename ExecutionContext,
- BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) CompletionToken
+ BOOST_ASIO_COMPLETION_TOKEN_FOR(void()) NullaryToken
BOOST_ASIO_DEFAULT_COMPLETION_TOKEN_TYPE(
typename ExecutionContext::executor_type)>
-BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(CompletionToken, void()) defer(
+BOOST_ASIO_INITFN_AUTO_RESULT_TYPE(NullaryToken, void()) defer(
ExecutionContext& ctx,
- BOOST_ASIO_MOVE_ARG(CompletionToken) token
+ BOOST_ASIO_MOVE_ARG(NullaryToken) token
BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(
typename ExecutionContext::executor_type),
- typename enable_if<is_convertible<
- ExecutionContext&, execution_context&>::value>::type* = 0);
+ typename constraint<is_convertible<
+ ExecutionContext&, execution_context&>::value>::type = 0);
} // namespace asio
} // namespace boost
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