| // |
| // experimental/as_single.hpp |
| // ~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| // |
| // Copyright (c) 2003-2020 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_EXPERIMENTAL_AS_SINGLE_HPP |
| #define ASIO_EXPERIMENTAL_AS_SINGLE_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/error_code.hpp" |
| |
| #include "asio/detail/push_options.hpp" |
| |
| namespace asio { |
| namespace experimental { |
| |
| /// Completion token type used to specify that an error produced by an |
| /// asynchronous operation is captured to an error_code variable. |
| /** |
| * The as_single_t class is used to indicate that any error_code produced |
| * by an asynchronous operation is captured to a specified variable. |
| */ |
| template <typename CompletionToken> |
| class as_single_t |
| { |
| public: |
| /// Default constructor. |
| /** |
| * This constructor is only valid if the underlying completion token is |
| * default constructible. |
| */ |
| ASIO_CONSTEXPR as_single_t() |
| : token_() |
| { |
| } |
| |
| /// Constructor. |
| template <typename T> |
| ASIO_CONSTEXPR explicit as_single_t( |
| ASIO_MOVE_ARG(T) completion_token) |
| : token_(ASIO_MOVE_CAST(T)(completion_token)) |
| { |
| } |
| |
| /// Adapts an executor to add the @c as_single_t completion token as the |
| /// default. |
| template <typename InnerExecutor> |
| struct executor_with_default : InnerExecutor |
| { |
| /// Specify @c as_single_t as the default completion token type. |
| typedef as_single_t default_completion_token_type; |
| |
| /// Construct the adapted executor from the inner executor type. |
| executor_with_default(const InnerExecutor& ex) ASIO_NOEXCEPT |
| : InnerExecutor(ex) |
| { |
| } |
| |
| /// Convert the specified executor to the inner executor type, then use |
| /// that to construct the adapted executor. |
| template <typename OtherExecutor> |
| executor_with_default(const OtherExecutor& ex, |
| typename enable_if< |
| is_convertible<OtherExecutor, InnerExecutor>::value |
| >::type* = 0) ASIO_NOEXCEPT |
| : InnerExecutor(ex) |
| { |
| } |
| }; |
| |
| /// Type alias to adapt an I/O object to use @c as_single_t as its |
| /// default completion token type. |
| #if defined(ASIO_HAS_ALIAS_TEMPLATES) \ |
| || defined(GENERATING_DOCUMENTATION) |
| template <typename T> |
| using as_default_on_t = typename T::template rebind_executor< |
| executor_with_default<typename T::executor_type> >::other; |
| #endif // defined(ASIO_HAS_ALIAS_TEMPLATES) |
| // || defined(GENERATING_DOCUMENTATION) |
| |
| /// Function helper to adapt an I/O object to use @c as_single_t as its |
| /// default completion token type. |
| template <typename T> |
| static typename decay<T>::type::template rebind_executor< |
| executor_with_default<typename decay<T>::type::executor_type> |
| >::other |
| as_default_on(ASIO_MOVE_ARG(T) object) |
| { |
| return typename decay<T>::type::template rebind_executor< |
| executor_with_default<typename decay<T>::type::executor_type> |
| >::other(ASIO_MOVE_CAST(T)(object)); |
| } |
| |
| //private: |
| CompletionToken token_; |
| }; |
| |
| /// Create a completion token to capture error_code values to a variable. |
| template <typename CompletionToken> |
| inline ASIO_CONSTEXPR as_single_t<typename decay<CompletionToken>::type> |
| as_single(ASIO_MOVE_ARG(CompletionToken) completion_token) |
| { |
| return as_single_t<typename decay<CompletionToken>::type>( |
| ASIO_MOVE_CAST(CompletionToken)(completion_token)); |
| } |
| |
| } // namespace experimental |
| } // namespace asio |
| |
| #include "asio/detail/pop_options.hpp" |
| |
| #include "asio/experimental/impl/as_single.hpp" |
| |
| #endif // ASIO_EXPERIMENTAL_AS_SINGLE_HPP |