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 //
 // basic_readable_pipe.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 BOOST_ASIO_BASIC_READABLE_PIPE_HPP
 #define BOOST_ASIO_BASIC_READABLE_PIPE_HPP
 
 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
 # pragma once
 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
 #include <boost/asio/detail/config.hpp>
 
 #if defined(BOOST_ASIO_HAS_PIPE) \
   || defined(GENERATING_DOCUMENTATION)
 
 #include <string>
 #include <utility>
 #include <boost/asio/any_io_executor.hpp>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/handler_type_requirements.hpp>
 #include <boost/asio/detail/io_object_impl.hpp>
 #include <boost/asio/detail/non_const_lvalue.hpp>
 #include <boost/asio/detail/throw_error.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/error.hpp>
 #include <boost/asio/execution_context.hpp>
 #if defined(BOOST_ASIO_HAS_IOCP)
 # include <boost/asio/detail/win_iocp_handle_service.hpp>
 #elif defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
 # include <boost/asio/detail/io_uring_descriptor_service.hpp>
 #else
 # include <boost/asio/detail/reactive_descriptor_service.hpp>
 #endif
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
 
 /// Provides pipe functionality.
 /**
  * The basic_readable_pipe class provides a wrapper over pipe
  * functionality.
  *
  * @par Thread Safety
  * @e Distinct @e objects: Safe.@n
  * @e Shared @e objects: Unsafe.
  */
 template <typename Executor = any_io_executor>
 class basic_readable_pipe
 {
 private:
   class initiate_async_read_some;
 
 public:
   /// The type of the executor associated with the object.
   typedef Executor executor_type;
 
   /// Rebinds the pipe type to another executor.
   template <typename Executor1>
   struct rebind_executor
   {
     /// The pipe type when rebound to the specified executor.
     typedef basic_readable_pipe<Executor1> other;
   };
 
   /// The native representation of a pipe.
 #if defined(GENERATING_DOCUMENTATION)
   typedef implementation_defined native_handle_type;
 #elif defined(BOOST_ASIO_HAS_IOCP)
   typedef detail::win_iocp_handle_service::native_handle_type
     native_handle_type;
 #elif defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
   typedef detail::io_uring_descriptor_service::native_handle_type
     native_handle_type;
 #else
   typedef detail::reactive_descriptor_service::native_handle_type
     native_handle_type;
 #endif
 
   /// A basic_readable_pipe is always the lowest layer.
   typedef basic_readable_pipe lowest_layer_type;
 
   /// Construct a basic_readable_pipe without opening it.
   /**
    * This constructor creates a pipe without opening it.
    *
    * @param ex The I/O executor that the pipe will use, by default, to dispatch
    * handlers for any asynchronous operations performed on the pipe.
    */
   explicit basic_readable_pipe(const executor_type& ex)
     : impl_(0, ex)
   {
   }
 
   /// Construct a basic_readable_pipe without opening it.
   /**
    * This constructor creates a pipe without opening it.
    *
    * @param context An execution context which provides the I/O executor that
    * the pipe will use, by default, to dispatch handlers for any asynchronous
    * operations performed on the pipe.
    */
   template <typename ExecutionContext>
   explicit basic_readable_pipe(ExecutionContext& context,
       constraint_t<
         is_convertible<ExecutionContext&, execution_context&>::value,
         defaulted_constraint
       > = defaulted_constraint())
     : impl_(0, 0, context)
   {
   }
 
   /// Construct a basic_readable_pipe on an existing native pipe.
   /**
    * This constructor creates a pipe object to hold an existing native
    * pipe.
    *
    * @param ex The I/O executor that the pipe will use, by default, to
    * dispatch handlers for any asynchronous operations performed on the
    * pipe.
    *
    * @param native_pipe A native pipe.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
   basic_readable_pipe(const executor_type& ex,
       const native_handle_type& native_pipe)
     : impl_(0, ex)
   {
     boost::system::error_code ec;
     impl_.get_service().assign(impl_.get_implementation(),
         native_pipe, ec);
     boost::asio::detail::throw_error(ec, "assign");
   }
 
   /// Construct a basic_readable_pipe on an existing native pipe.
   /**
    * This constructor creates a pipe object to hold an existing native
    * pipe.
    *
    * @param context An execution context which provides the I/O executor that
    * the pipe will use, by default, to dispatch handlers for any
    * asynchronous operations performed on the pipe.
    *
    * @param native_pipe A native pipe.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
   template <typename ExecutionContext>
   basic_readable_pipe(ExecutionContext& context,
       const native_handle_type& native_pipe,
       constraint_t<
         is_convertible<ExecutionContext&, execution_context&>::value
       > = 0)
     : impl_(0, 0, context)
   {
     boost::system::error_code ec;
     impl_.get_service().assign(impl_.get_implementation(),
         native_pipe, ec);
     boost::asio::detail::throw_error(ec, "assign");
   }
 
   /// Move-construct a basic_readable_pipe from another.
   /**
    * This constructor moves a pipe from one object to another.
    *
    * @param other The other basic_readable_pipe object from which the move will
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
    * constructed using the @c basic_readable_pipe(const executor_type&)
    * constructor.
    */
   basic_readable_pipe(basic_readable_pipe&& other)
     : impl_(std::move(other.impl_))
   {
   }
 
   /// Move-assign a basic_readable_pipe from another.
   /**
    * This assignment operator moves a pipe from one object to another.
    *
    * @param other The other basic_readable_pipe object from which the move will
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
    * constructed using the @c basic_readable_pipe(const executor_type&)
    * constructor.
    */
   basic_readable_pipe& operator=(basic_readable_pipe&& other)
   {
     impl_ = std::move(other.impl_);
     return *this;
   }
 
   // All pipes have access to each other's implementations.
   template <typename Executor1>
   friend class basic_readable_pipe;
 
   /// Move-construct a basic_readable_pipe from a pipe of another executor type.
   /**
    * This constructor moves a pipe from one object to another.
    *
    * @param other The other basic_readable_pipe object from which the move will
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
    * constructed using the @c basic_readable_pipe(const executor_type&)
    * constructor.
    */
   template <typename Executor1>
   basic_readable_pipe(basic_readable_pipe<Executor1>&& other,
       constraint_t<
         is_convertible<Executor1, Executor>::value,
         defaulted_constraint
       > = defaulted_constraint())
     : impl_(std::move(other.impl_))
   {
   }
 
   /// Move-assign a basic_readable_pipe from a pipe of another executor type.
   /**
    * This assignment operator moves a pipe from one object to another.
    *
    * @param other The other basic_readable_pipe object from which the move will
    * occur.
    *
    * @note Following the move, the moved-from object is in the same state as if
    * constructed using the @c basic_readable_pipe(const executor_type&)
    * constructor.
    */
   template <typename Executor1>
   constraint_t<
     is_convertible<Executor1, Executor>::value,
     basic_readable_pipe&
   > operator=(basic_readable_pipe<Executor1>&& other)
   {
     basic_readable_pipe tmp(std::move(other));
     impl_ = std::move(tmp.impl_);
     return *this;
   }
 
   /// Destroys the pipe.
   /**
    * This function destroys the pipe, cancelling any outstanding
    * asynchronous wait operations associated with the pipe as if by
    * calling @c cancel.
    */
   ~basic_readable_pipe()
   {
   }
 
   /// Get the executor associated with the object.
   const executor_type& get_executor() noexcept
   {
     return impl_.get_executor();
   }
 
   /// Get a reference to the lowest layer.
   /**
    * This function returns a reference to the lowest layer in a stack of
    * layers. Since a basic_readable_pipe cannot contain any further layers, it
    * simply returns a reference to itself.
    *
    * @return A reference to the lowest layer in the stack of layers. Ownership
    * is not transferred to the caller.
    */
   lowest_layer_type& lowest_layer()
   {
     return *this;
   }
 
   /// Get a const reference to the lowest layer.
   /**
    * This function returns a const reference to the lowest layer in a stack of
    * layers. Since a basic_readable_pipe cannot contain any further layers, it
    * simply returns a reference to itself.
    *
    * @return A const reference to the lowest layer in the stack of layers.
    * Ownership is not transferred to the caller.
    */
   const lowest_layer_type& lowest_layer() const
   {
     return *this;
   }
 
   /// Assign an existing native pipe to the pipe.
   /*
    * This function opens the pipe to hold an existing native pipe.
    *
    * @param native_pipe A native pipe.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
   void assign(const native_handle_type& native_pipe)
   {
     boost::system::error_code ec;
     impl_.get_service().assign(impl_.get_implementation(), native_pipe, ec);
     boost::asio::detail::throw_error(ec, "assign");
   }
 
   /// Assign an existing native pipe to the pipe.
   /*
    * This function opens the pipe to hold an existing native pipe.
    *
    * @param native_pipe A native pipe.
    *
    * @param ec Set to indicate what error occurred, if any.
    */
   BOOST_ASIO_SYNC_OP_VOID assign(const native_handle_type& native_pipe,
       boost::system::error_code& ec)
   {
     impl_.get_service().assign(impl_.get_implementation(), native_pipe, ec);
     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Determine whether the pipe is open.
   bool is_open() const
   {
     return impl_.get_service().is_open(impl_.get_implementation());
   }
 
   /// Close the pipe.
   /**
    * This function is used to close the pipe. Any asynchronous read operations
    * will be cancelled immediately, and will complete with the
    * boost::asio::error::operation_aborted error.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
   void close()
   {
     boost::system::error_code ec;
     impl_.get_service().close(impl_.get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "close");
   }
 
   /// Close the pipe.
   /**
    * This function is used to close the pipe. Any asynchronous read operations
    * will be cancelled immediately, and will complete with the
    * boost::asio::error::operation_aborted error.
    *
    * @param ec Set to indicate what error occurred, if any.
    */
   BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
   {
     impl_.get_service().close(impl_.get_implementation(), ec);
     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Release ownership of the underlying native pipe.
   /**
    * This function causes all outstanding asynchronous read operations to
    * finish immediately, and the handlers for cancelled operations will be
    * passed the boost::asio::error::operation_aborted error. Ownership of the
    * native pipe is then transferred to the caller.
    *
    * @throws boost::system::system_error Thrown on failure.
    *
    * @note This function is unsupported on Windows versions prior to Windows
    * 8.1, and will fail with boost::asio::error::operation_not_supported on
    * these platforms.
    */
 #if defined(BOOST_ASIO_MSVC) && (BOOST_ASIO_MSVC >= 1400) \
   && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0603)
   __declspec(deprecated("This function always fails with "
         "operation_not_supported when used on Windows versions "
         "prior to Windows 8.1."))
 #endif
   native_handle_type release()
   {
     boost::system::error_code ec;
     native_handle_type s = impl_.get_service().release(
         impl_.get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "release");
     return s;
   }
 
   /// Release ownership of the underlying native pipe.
   /**
    * This function causes all outstanding asynchronous read operations to
    * finish immediately, and the handlers for cancelled operations will be
    * passed the boost::asio::error::operation_aborted error. Ownership of the
    * native pipe is then transferred to the caller.
    *
    * @param ec Set to indicate what error occurred, if any.
    *
    * @note This function is unsupported on Windows versions prior to Windows
    * 8.1, and will fail with boost::asio::error::operation_not_supported on
    * these platforms.
    */
 #if defined(BOOST_ASIO_MSVC) && (BOOST_ASIO_MSVC >= 1400) \
   && (!defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0603)
   __declspec(deprecated("This function always fails with "
         "operation_not_supported when used on Windows versions "
         "prior to Windows 8.1."))
 #endif
   native_handle_type release(boost::system::error_code& ec)
   {
     return impl_.get_service().release(impl_.get_implementation(), ec);
   }
 
   /// Get the native pipe representation.
   /**
    * This function may be used to obtain the underlying representation of the
    * pipe. This is intended to allow access to native pipe
    * functionality that is not otherwise provided.
    */
   native_handle_type native_handle()
   {
     return impl_.get_service().native_handle(impl_.get_implementation());
   }
 
   /// Cancel all asynchronous operations associated with the pipe.
   /**
    * This function causes all outstanding asynchronous read operations to finish
    * immediately, and the handlers for cancelled operations will be passed the
    * boost::asio::error::operation_aborted error.
    *
    * @throws boost::system::system_error Thrown on failure.
    */
   void cancel()
   {
     boost::system::error_code ec;
     impl_.get_service().cancel(impl_.get_implementation(), ec);
     boost::asio::detail::throw_error(ec, "cancel");
   }
 
   /// Cancel all asynchronous operations associated with the pipe.
   /**
    * This function causes all outstanding asynchronous read operations to finish
    * immediately, and the handlers for cancelled operations will be passed the
    * boost::asio::error::operation_aborted error.
    *
    * @param ec Set to indicate what error occurred, if any.
    */
   BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
   {
     impl_.get_service().cancel(impl_.get_implementation(), ec);
     BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
   }
 
   /// Read some data from the pipe.
   /**
    * This function is used to read data from the pipe. The function call will
    * block until one or more bytes of data has been read successfully, or until
    * an error occurs.
    *
    * @param buffers One or more buffers into which the data will be read.
    *
    * @returns The number of bytes read.
    *
    * @throws boost::system::system_error Thrown on failure. An error code of
    * boost::asio::error::eof indicates that the connection was closed by the
    * peer.
    *
    * @note The read_some operation may not read all of the requested number of
    * bytes. Consider using the @ref read function if you need to ensure that
    * the requested amount of data is read before the blocking operation
    * completes.
    *
    * @par Example
    * To read into a single data buffer use the @ref buffer function as follows:
    * @code
    * basic_readable_pipe.read_some(boost::asio::buffer(data, size));
    * @endcode
    * See the @ref buffer documentation for information on reading into multiple
    * buffers in one go, and how to use it with arrays, boost::array or
    * std::vector.
    */
   template <typename MutableBufferSequence>
   std::size_t read_some(const MutableBufferSequence& buffers)
   {
     boost::system::error_code ec;
     std::size_t s = impl_.get_service().read_some(
         impl_.get_implementation(), buffers, ec);
     boost::asio::detail::throw_error(ec, "read_some");
     return s;
   }
 
   /// Read some data from the pipe.
   /**
    * This function is used to read data from the pipe. The function call will
    * block until one or more bytes of data has been read successfully, or until
    * an error occurs.
    *
    * @param buffers One or more buffers into which the data will be read.
    *
    * @param ec Set to indicate what error occurred, if any.
    *
    * @returns The number of bytes read. Returns 0 if an error occurred.
    *
    * @note The read_some operation may not read all of the requested number of
    * bytes. Consider using the @ref read function if you need to ensure that
    * the requested amount of data is read before the blocking operation
    * completes.
    */
   template <typename MutableBufferSequence>
   std::size_t read_some(const MutableBufferSequence& buffers,
       boost::system::error_code& ec)
   {
     return impl_.get_service().read_some(
         impl_.get_implementation(), buffers, ec);
   }
 
   /// Start an asynchronous read.
   /**
    * This function is used to asynchronously read data from the pipe. It is an
    * initiating function for an @ref asynchronous_operation, and always returns
    * immediately.
    *
    * @param buffers One or more buffers into which the data will be read.
    * Although the buffers object may be copied as necessary, ownership of the
    * underlying memory blocks is retained by the caller, which must guarantee
    * that they remain valid until the completion handler is called.
    *
    * @param token The @ref completion_token that will be used to produce a
    * completion handler, which will be called when the read completes.
    * Potential completion tokens include @ref use_future, @ref use_awaitable,
    * @ref yield_context, or a function object with the correct completion
    * signature. The function signature of the completion handler must be:
    * @code void handler(
    *   const boost::system::error_code& error, // Result of operation.
    *   std::size_t bytes_transferred // Number of bytes read.
    * ); @endcode
    * Regardless of whether the asynchronous operation completes immediately or
    * not, the completion handler will not be invoked from within this function.
    * On immediate completion, invocation of the handler will be performed in a
    * manner equivalent to using boost::asio::post().
    *
    * @par Completion Signature
    * @code void(boost::system::error_code, std::size_t) @endcode
    *
    * @note The read operation may not read all of the requested number of bytes.
    * Consider using the @ref async_read function if you need to ensure that the
    * requested amount of data is read before the asynchronous operation
    * completes.
    *
    * @par Example
    * To read into a single data buffer use the @ref buffer function as follows:
    * @code
    * basic_readable_pipe.async_read_some(
    *     boost::asio::buffer(data, size), handler);
    * @endcode
    * See the @ref buffer documentation for information on reading into multiple
    * buffers in one go, and how to use it with arrays, boost::array or
    * std::vector.
    */
   template <typename MutableBufferSequence,
       BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code,
         std::size_t)) ReadToken = default_completion_token_t<executor_type>>
   auto async_read_some(const MutableBufferSequence& buffers,
       ReadToken&& token = default_completion_token_t<executor_type>())
     -> decltype(
       async_initiate<ReadToken,
         void (boost::system::error_code, std::size_t)>(
           declval<initiate_async_read_some>(), token, buffers))
   {
     return async_initiate<ReadToken,
       void (boost::system::error_code, std::size_t)>(
         initiate_async_read_some(this), token, buffers);
   }
 
 private:
   // Disallow copying and assignment.
   basic_readable_pipe(const basic_readable_pipe&) = delete;
   basic_readable_pipe& operator=(const basic_readable_pipe&) = delete;
 
   class initiate_async_read_some
   {
   public:
     typedef Executor executor_type;
 
     explicit initiate_async_read_some(basic_readable_pipe* self)
       : self_(self)
     {
     }
 
     const executor_type& get_executor() const noexcept
     {
       return self_->get_executor();
     }
 
     template <typename ReadHandler, typename MutableBufferSequence>
     void operator()(ReadHandler&& handler,
         const MutableBufferSequence& buffers) const
     {
       // If you get an error on the following line it means that your handler
       // does not meet the documented type requirements for a ReadHandler.
       BOOST_ASIO_READ_HANDLER_CHECK(ReadHandler, handler) type_check;
 
       detail::non_const_lvalue<ReadHandler> handler2(handler);
       self_->impl_.get_service().async_read_some(
           self_->impl_.get_implementation(), buffers,
           handler2.value, self_->impl_.get_executor());
     }
 
   private:
     basic_readable_pipe* self_;
   };
 
 #if defined(BOOST_ASIO_HAS_IOCP)
   detail::io_object_impl<detail::win_iocp_handle_service, Executor> impl_;
 #elif defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
   detail::io_object_impl<detail::io_uring_descriptor_service, Executor> impl_;
 #else
   detail::io_object_impl<detail::reactive_descriptor_service, Executor> impl_;
 #endif
 };
 
 } // namespace asio
 } // namespace boost
 
 #include <boost/asio/detail/pop_options.hpp>
 
 #endif // defined(BOOST_ASIO_HAS_PIPE)
        //   || defined(GENERATING_DOCUMENTATION)
 
 #endif // BOOST_ASIO_BASIC_READABLE_PIPE_HPP

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