// // bind_executor.hpp // ~~~~~~~~~~~~~~~~~ // // Copyright (c) 2003-2023 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_BIND_EXECUTOR_HPP #define ASIO_BIND_EXECUTOR_HPP #if defined(_MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) #include "asio/detail/config.hpp" #include "asio/detail/type_traits.hpp" #include "asio/detail/variadic_templates.hpp" #include "asio/associated_executor.hpp" #include "asio/associator.hpp" #include "asio/async_result.hpp" #include "asio/execution/executor.hpp" #include "asio/execution_context.hpp" #include "asio/is_executor.hpp" #include "asio/uses_executor.hpp" #include "asio/detail/push_options.hpp" namespace asio { namespace detail { // Helper to automatically define nested typedef result_type. template struct executor_binder_result_type { protected: typedef void result_type_or_void; }; template struct executor_binder_result_type::type> { typedef typename T::result_type result_type; protected: typedef result_type result_type_or_void; }; template struct executor_binder_result_type { typedef R result_type; protected: typedef result_type result_type_or_void; }; template struct executor_binder_result_type { typedef R result_type; protected: typedef result_type result_type_or_void; }; template struct executor_binder_result_type { typedef R result_type; protected: typedef result_type result_type_or_void; }; template struct executor_binder_result_type { typedef R result_type; protected: typedef result_type result_type_or_void; }; template struct executor_binder_result_type { typedef R result_type; protected: typedef result_type result_type_or_void; }; template struct executor_binder_result_type { typedef R result_type; protected: typedef result_type result_type_or_void; }; // Helper to automatically define nested typedef argument_type. template struct executor_binder_argument_type {}; template struct executor_binder_argument_type::type> { typedef typename T::argument_type argument_type; }; template struct executor_binder_argument_type { typedef A1 argument_type; }; template struct executor_binder_argument_type { typedef A1 argument_type; }; // Helper to automatically define nested typedefs first_argument_type and // second_argument_type. template struct executor_binder_argument_types {}; template struct executor_binder_argument_types::type> { typedef typename T::first_argument_type first_argument_type; typedef typename T::second_argument_type second_argument_type; }; template struct executor_binder_argument_type { typedef A1 first_argument_type; typedef A2 second_argument_type; }; template struct executor_binder_argument_type { typedef A1 first_argument_type; typedef A2 second_argument_type; }; // Helper to perform uses_executor construction of the target type, if // required. template class executor_binder_base; template class executor_binder_base { protected: template executor_binder_base(ASIO_MOVE_ARG(E) e, ASIO_MOVE_ARG(U) u) : executor_(ASIO_MOVE_CAST(E)(e)), target_(executor_arg_t(), executor_, ASIO_MOVE_CAST(U)(u)) { } Executor executor_; T target_; }; template class executor_binder_base { protected: template executor_binder_base(ASIO_MOVE_ARG(E) e, ASIO_MOVE_ARG(U) u) : executor_(ASIO_MOVE_CAST(E)(e)), target_(ASIO_MOVE_CAST(U)(u)) { } Executor executor_; T target_; }; // Helper to enable SFINAE on zero-argument operator() below. template struct executor_binder_result_of0 { typedef void type; }; template struct executor_binder_result_of0::type>::type> { typedef typename result_of::type type; }; } // namespace detail /// A call wrapper type to bind an executor of type @c Executor to an object of /// type @c T. template class executor_binder #if !defined(GENERATING_DOCUMENTATION) : public detail::executor_binder_result_type, public detail::executor_binder_argument_type, public detail::executor_binder_argument_types, private detail::executor_binder_base< T, Executor, uses_executor::value> #endif // !defined(GENERATING_DOCUMENTATION) { public: /// The type of the target object. typedef T target_type; /// The type of the associated executor. typedef Executor executor_type; #if defined(GENERATING_DOCUMENTATION) /// The return type if a function. /** * The type of @c result_type is based on the type @c T of the wrapper's * target object: * * @li if @c T is a pointer to function type, @c result_type is a synonym for * the return type of @c T; * * @li if @c T is a class type with a member type @c result_type, then @c * result_type is a synonym for @c T::result_type; * * @li otherwise @c result_type is not defined. */ typedef see_below result_type; /// The type of the function's argument. /** * The type of @c argument_type is based on the type @c T of the wrapper's * target object: * * @li if @c T is a pointer to a function type accepting a single argument, * @c argument_type is a synonym for the return type of @c T; * * @li if @c T is a class type with a member type @c argument_type, then @c * argument_type is a synonym for @c T::argument_type; * * @li otherwise @c argument_type is not defined. */ typedef see_below argument_type; /// The type of the function's first argument. /** * The type of @c first_argument_type is based on the type @c T of the * wrapper's target object: * * @li if @c T is a pointer to a function type accepting two arguments, @c * first_argument_type is a synonym for the return type of @c T; * * @li if @c T is a class type with a member type @c first_argument_type, * then @c first_argument_type is a synonym for @c T::first_argument_type; * * @li otherwise @c first_argument_type is not defined. */ typedef see_below first_argument_type; /// The type of the function's second argument. /** * The type of @c second_argument_type is based on the type @c T of the * wrapper's target object: * * @li if @c T is a pointer to a function type accepting two arguments, @c * second_argument_type is a synonym for the return type of @c T; * * @li if @c T is a class type with a member type @c first_argument_type, * then @c second_argument_type is a synonym for @c T::second_argument_type; * * @li otherwise @c second_argument_type is not defined. */ typedef see_below second_argument_type; #endif // defined(GENERATING_DOCUMENTATION) /// Construct an executor wrapper for the specified object. /** * This constructor is only valid if the type @c T is constructible from type * @c U. */ template executor_binder(executor_arg_t, const executor_type& e, ASIO_MOVE_ARG(U) u) : base_type(e, ASIO_MOVE_CAST(U)(u)) { } /// Copy constructor. executor_binder(const executor_binder& other) : base_type(other.get_executor(), other.get()) { } /// Construct a copy, but specify a different executor. executor_binder(executor_arg_t, const executor_type& e, const executor_binder& other) : base_type(e, other.get()) { } /// Construct a copy of a different executor wrapper type. /** * This constructor is only valid if the @c Executor type is constructible * from type @c OtherExecutor, and the type @c T is constructible from type * @c U. */ template executor_binder(const executor_binder& other) : base_type(other.get_executor(), other.get()) { } /// Construct a copy of a different executor wrapper type, but specify a /// different executor. /** * This constructor is only valid if the type @c T is constructible from type * @c U. */ template executor_binder(executor_arg_t, const executor_type& e, const executor_binder& other) : base_type(e, other.get()) { } #if defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION) /// Move constructor. executor_binder(executor_binder&& other) : base_type(ASIO_MOVE_CAST(executor_type)(other.get_executor()), ASIO_MOVE_CAST(T)(other.get())) { } /// Move construct the target object, but specify a different executor. executor_binder(executor_arg_t, const executor_type& e, executor_binder&& other) : base_type(e, ASIO_MOVE_CAST(T)(other.get())) { } /// Move construct from a different executor wrapper type. template executor_binder(executor_binder&& other) : base_type(ASIO_MOVE_CAST(OtherExecutor)(other.get_executor()), ASIO_MOVE_CAST(U)(other.get())) { } /// Move construct from a different executor wrapper type, but specify a /// different executor. template executor_binder(executor_arg_t, const executor_type& e, executor_binder&& other) : base_type(e, ASIO_MOVE_CAST(U)(other.get())) { } #endif // defined(ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION) /// Destructor. ~executor_binder() { } /// Obtain a reference to the target object. target_type& get() ASIO_NOEXCEPT { return this->target_; } /// Obtain a reference to the target object. const target_type& get() const ASIO_NOEXCEPT { return this->target_; } /// Obtain the associated executor. executor_type get_executor() const ASIO_NOEXCEPT { return this->executor_; } #if defined(GENERATING_DOCUMENTATION) template auto operator()(Args&& ...); template auto operator()(Args&& ...) const; #elif defined(ASIO_HAS_VARIADIC_TEMPLATES) /// Forwarding function call operator. template typename result_of::type operator()( ASIO_MOVE_ARG(Args)... args) { return this->target_(ASIO_MOVE_CAST(Args)(args)...); } /// Forwarding function call operator. template typename result_of::type operator()( ASIO_MOVE_ARG(Args)... args) const { return this->target_(ASIO_MOVE_CAST(Args)(args)...); } #elif defined(ASIO_HAS_STD_TYPE_TRAITS) && !defined(_MSC_VER) typename detail::executor_binder_result_of0::type operator()() { return this->target_(); } typename detail::executor_binder_result_of0::type operator()() const { return this->target_(); } #define ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF(n) \ template \ typename result_of::type operator()( \ ASIO_VARIADIC_MOVE_PARAMS(n)) \ { \ return this->target_(ASIO_VARIADIC_MOVE_ARGS(n)); \ } \ \ template \ typename result_of::type operator()( \ ASIO_VARIADIC_MOVE_PARAMS(n)) const \ { \ return this->target_(ASIO_VARIADIC_MOVE_ARGS(n)); \ } \ /**/ ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF) #undef ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF #else // defined(ASIO_HAS_STD_TYPE_TRAITS) && !defined(_MSC_VER) typedef typename detail::executor_binder_result_type::result_type_or_void result_type_or_void; result_type_or_void operator()() { return this->target_(); } result_type_or_void operator()() const { return this->target_(); } #define ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF(n) \ template \ result_type_or_void operator()( \ ASIO_VARIADIC_MOVE_PARAMS(n)) \ { \ return this->target_(ASIO_VARIADIC_MOVE_ARGS(n)); \ } \ \ template \ result_type_or_void operator()( \ ASIO_VARIADIC_MOVE_PARAMS(n)) const \ { \ return this->target_(ASIO_VARIADIC_MOVE_ARGS(n)); \ } \ /**/ ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF) #undef ASIO_PRIVATE_BIND_EXECUTOR_CALL_DEF #endif // defined(ASIO_HAS_STD_TYPE_TRAITS) && !defined(_MSC_VER) private: typedef detail::executor_binder_base::value> base_type; }; /// Associate an object of type @c T with an executor of type @c Executor. template ASIO_NODISCARD inline executor_binder::type, Executor> bind_executor(const Executor& ex, ASIO_MOVE_ARG(T) t, typename constraint< is_executor::value || execution::is_executor::value >::type = 0) { return executor_binder::type, Executor>( executor_arg_t(), ex, ASIO_MOVE_CAST(T)(t)); } /// Associate an object of type @c T with an execution context's executor. template ASIO_NODISCARD inline executor_binder::type, typename ExecutionContext::executor_type> bind_executor(ExecutionContext& ctx, ASIO_MOVE_ARG(T) t, typename constraint::value>::type = 0) { return executor_binder::type, typename ExecutionContext::executor_type>( executor_arg_t(), ctx.get_executor(), ASIO_MOVE_CAST(T)(t)); } #if !defined(GENERATING_DOCUMENTATION) template struct uses_executor, Executor> : true_type {}; namespace detail { template class executor_binder_completion_handler_async_result { public: template explicit executor_binder_completion_handler_async_result(T&) { } }; template class executor_binder_completion_handler_async_result< TargetAsyncResult, Executor, typename void_type< typename TargetAsyncResult::completion_handler_type >::type> { public: typedef executor_binder< typename TargetAsyncResult::completion_handler_type, Executor> completion_handler_type; explicit executor_binder_completion_handler_async_result( typename TargetAsyncResult::completion_handler_type& handler) : target_(handler) { } typename TargetAsyncResult::return_type get() { return target_.get(); } private: TargetAsyncResult target_; }; template struct executor_binder_async_result_return_type { }; template struct executor_binder_async_result_return_type< TargetAsyncResult, typename void_type< typename TargetAsyncResult::return_type >::type> { typedef typename TargetAsyncResult::return_type return_type; }; } // namespace detail template class async_result, Signature> : public detail::executor_binder_completion_handler_async_result< async_result, Executor>, public detail::executor_binder_async_result_return_type< async_result > { public: explicit async_result(executor_binder& b) : detail::executor_binder_completion_handler_async_result< async_result, Executor>(b.get()) { } template struct init_wrapper { template init_wrapper(const Executor& ex, ASIO_MOVE_ARG(Init) init) : ex_(ex), initiation_(ASIO_MOVE_CAST(Init)(init)) { } #if defined(ASIO_HAS_VARIADIC_TEMPLATES) template void operator()( ASIO_MOVE_ARG(Handler) handler, ASIO_MOVE_ARG(Args)... args) { ASIO_MOVE_CAST(Initiation)(initiation_)( executor_binder::type, Executor>( executor_arg_t(), ex_, ASIO_MOVE_CAST(Handler)(handler)), ASIO_MOVE_CAST(Args)(args)...); } template void operator()( ASIO_MOVE_ARG(Handler) handler, ASIO_MOVE_ARG(Args)... args) const { initiation_( executor_binder::type, Executor>( executor_arg_t(), ex_, ASIO_MOVE_CAST(Handler)(handler)), ASIO_MOVE_CAST(Args)(args)...); } #else // defined(ASIO_HAS_VARIADIC_TEMPLATES) template void operator()( ASIO_MOVE_ARG(Handler) handler) { ASIO_MOVE_CAST(Initiation)(initiation_)( executor_binder::type, Executor>( executor_arg_t(), ex_, ASIO_MOVE_CAST(Handler)(handler))); } template void operator()( ASIO_MOVE_ARG(Handler) handler) const { initiation_( executor_binder::type, Executor>( executor_arg_t(), ex_, ASIO_MOVE_CAST(Handler)(handler))); } #define ASIO_PRIVATE_INIT_WRAPPER_DEF(n) \ template \ void operator()( \ ASIO_MOVE_ARG(Handler) handler, \ ASIO_VARIADIC_MOVE_PARAMS(n)) \ { \ ASIO_MOVE_CAST(Initiation)(initiation_)( \ executor_binder::type, Executor>( \ executor_arg_t(), ex_, ASIO_MOVE_CAST(Handler)(handler)), \ ASIO_VARIADIC_MOVE_ARGS(n)); \ } \ \ template \ void operator()( \ ASIO_MOVE_ARG(Handler) handler, \ ASIO_VARIADIC_MOVE_PARAMS(n)) const \ { \ initiation_( \ executor_binder::type, Executor>( \ executor_arg_t(), ex_, ASIO_MOVE_CAST(Handler)(handler)), \ ASIO_VARIADIC_MOVE_ARGS(n)); \ } \ /**/ ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_INIT_WRAPPER_DEF) #undef ASIO_PRIVATE_INIT_WRAPPER_DEF #endif // defined(ASIO_HAS_VARIADIC_TEMPLATES) Executor ex_; Initiation initiation_; }; #if defined(ASIO_HAS_VARIADIC_TEMPLATES) template static ASIO_INITFN_DEDUCED_RESULT_TYPE(T, Signature, (async_initiate( declval::type> >(), declval().get(), declval()...))) initiate( ASIO_MOVE_ARG(Initiation) initiation, ASIO_MOVE_ARG(RawCompletionToken) token, ASIO_MOVE_ARG(Args)... args) { return async_initiate( init_wrapper::type>( token.get_executor(), ASIO_MOVE_CAST(Initiation)(initiation)), token.get(), ASIO_MOVE_CAST(Args)(args)...); } #else // defined(ASIO_HAS_VARIADIC_TEMPLATES) template static ASIO_INITFN_DEDUCED_RESULT_TYPE(T, Signature, (async_initiate( declval::type> >(), declval().get()))) initiate( ASIO_MOVE_ARG(Initiation) initiation, ASIO_MOVE_ARG(RawCompletionToken) token) { return async_initiate( init_wrapper::type>( token.get_executor(), ASIO_MOVE_CAST(Initiation)(initiation)), token.get()); } #define ASIO_PRIVATE_INITIATE_DEF(n) \ template \ static ASIO_INITFN_DEDUCED_RESULT_TYPE(T, Signature, \ (async_initiate( \ declval::type> >(), \ declval().get(), \ ASIO_VARIADIC_MOVE_DECLVAL(n)))) \ initiate( \ ASIO_MOVE_ARG(Initiation) initiation, \ ASIO_MOVE_ARG(RawCompletionToken) token, \ ASIO_VARIADIC_MOVE_PARAMS(n)) \ { \ return async_initiate( \ init_wrapper::type>( \ token.get_executor(), ASIO_MOVE_CAST(Initiation)(initiation)), \ token.get(), ASIO_VARIADIC_MOVE_ARGS(n)); \ } \ /**/ ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_INITIATE_DEF) #undef ASIO_PRIVATE_INITIATE_DEF #endif // defined(ASIO_HAS_VARIADIC_TEMPLATES) private: async_result(const async_result&) ASIO_DELETED; async_result& operator=(const async_result&) ASIO_DELETED; }; template