text: //
  // windows/basic_random_access_handle.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 BOOST_ASIO_WINDOWS_BASIC_RANDOM_ACCESS_HANDLE_HPP
  #define BOOST_ASIO_WINDOWS_BASIC_RANDOM_ACCESS_HANDLE_HPP
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  # pragma once
  #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  
  #include <boost/asio/detail/config.hpp>
  #include <boost/asio/windows/basic_overlapped_handle.hpp>
  
  #if defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE) \
    || defined(GENERATING_DOCUMENTATION)
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  namespace windows {
  
  /// Provides random-access handle functionality.
  /**
   * The windows::basic_random_access_handle class provides asynchronous and
   * blocking random-access handle functionality.
   *
   * @par Thread Safety
   * @e Distinct @e objects: Safe.@n
   * @e Shared @e objects: Unsafe.
   */
  template <typename Executor = executor>
  class basic_random_access_handle
    : public basic_overlapped_handle<Executor>
  {
  public:
    /// The type of the executor associated with the object.
    typedef Executor executor_type;
  
    /// The native representation of a handle.
  #if defined(GENERATING_DOCUMENTATION)
    typedef implementation_defined native_handle_type;
  #else
    typedef boost::asio::detail::win_iocp_handle_service::native_handle_type
      native_handle_type;
  #endif
  
    /// Construct a random-access handle without opening it.
    /**
     * This constructor creates a random-access handle without opening it.
     *
     * @param ex The I/O executor that the random-access handle will use, by
     * default, to dispatch handlers for any asynchronous operations performed on
     * the random-access handle.
     */
    explicit basic_random_access_handle(const executor_type& ex)
      : basic_overlapped_handle<Executor>(ex)
    {
    }
  
    /// Construct a random-access handle without opening it.
    /**
     * This constructor creates a random-access handle without opening it. The
     * handle needs to be opened or assigned before data can be sent or received
     * on it.
     *
     * @param context An execution context which provides the I/O executor that
     * the random-access handle will use, by default, to dispatch handlers for any
     * asynchronous operations performed on the random-access handle.
     */
    template <typename ExecutionContext>
    explicit basic_random_access_handle(ExecutionContext& context,
        typename enable_if<
          is_convertible<ExecutionContext&, execution_context&>::value,
          basic_random_access_handle
        >::type* = 0)
      : basic_overlapped_handle<Executor>(context)
    {
    }
  
    /// Construct a random-access handle on an existing native handle.
    /**
     * This constructor creates a random-access handle object to hold an existing
     * native handle.
     *
     * @param ex The I/O executor that the random-access handle will use, by
     * default, to dispatch handlers for any asynchronous operations performed on
     * the random-access handle.
     *
     * @param handle The new underlying handle implementation.
     *
     * @throws boost::system::system_error Thrown on failure.
     */
    basic_random_access_handle(const executor_type& ex,
        const native_handle_type& handle)
      : basic_overlapped_handle<Executor>(ex, handle)
    {
    }
  
    /// Construct a random-access handle on an existing native handle.
    /**
     * This constructor creates a random-access handle object to hold an existing
     * native handle.
     *
     * @param context An execution context which provides the I/O executor that
     * the random-access handle will use, by default, to dispatch handlers for any
     * asynchronous operations performed on the random-access handle.
     *
     * @param handle The new underlying handle implementation.
     *
     * @throws boost::system::system_error Thrown on failure.
     */
    template <typename ExecutionContext>
    basic_random_access_handle(ExecutionContext& context,
        const native_handle_type& handle,
        typename enable_if<
          is_convertible<ExecutionContext&, execution_context&>::value
        >::type* = 0)
      : basic_overlapped_handle<Executor>(context, handle)
    {
    }
  
  #if defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
    /// Move-construct a random-access handle from another.
    /**
     * This constructor moves a random-access handle from one object to another.
     *
     * @param other The other random-access handle 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_random_access_handle(const executor_type&)
     * constructor.
     */
    basic_random_access_handle(basic_random_access_handle&& other)
      : basic_overlapped_handle<Executor>(std::move(other))
    {
    }
  
    /// Move-assign a random-access handle from another.
    /**
     * This assignment operator moves a random-access handle from one object to
     * another.
     *
     * @param other The other random-access handle 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_random_access_handle(const executor_type&)
     * constructor.
     */
    basic_random_access_handle& operator=(basic_random_access_handle&& other)
    {
      basic_overlapped_handle<Executor>::operator=(std::move(other));
      return *this;
    }
  #endif // defined(BOOST_ASIO_HAS_MOVE) || defined(GENERATING_DOCUMENTATION)
  
    /// Write some data to the handle at the specified offset.
    /**
     * This function is used to write data to the random-access handle. The
     * function call will block until one or more bytes of the data has been
     * written successfully, or until an error occurs.
     *
     * @param offset The offset at which the data will be written.
     *
     * @param buffers One or more data buffers to be written to the handle.
     *
     * @returns The number of bytes written.
     *
     * @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 write_some_at operation may not write all of the data. Consider
     * using the @ref write_at function if you need to ensure that all data is
     * written before the blocking operation completes.
     *
     * @par Example
     * To write a single data buffer use the @ref buffer function as follows:
     * @code
     * handle.write_some_at(42, boost::asio::buffer(data, size));
     * @endcode
     * See the @ref buffer documentation for information on writing multiple
     * buffers in one go, and how to use it with arrays, boost::array or
     * std::vector.
     */
    template <typename ConstBufferSequence>
    std::size_t write_some_at(uint64_t offset,
        const ConstBufferSequence& buffers)
    {
      boost::system::error_code ec;
      std::size_t s = this->impl_.get_service().write_some_at(
          this->impl_.get_implementation(), offset, buffers, ec);
      boost::asio::detail::throw_error(ec, "write_some_at");
      return s;
    }
  
    /// Write some data to the handle at the specified offset.
    /**
     * This function is used to write data to the random-access handle. The
     * function call will block until one or more bytes of the data has been
     * written successfully, or until an error occurs.
     *
     * @param offset The offset at which the data will be written.
     *
     * @param buffers One or more data buffers to be written to the handle.
     *
     * @param ec Set to indicate what error occurred, if any.
     *
     * @returns The number of bytes written. Returns 0 if an error occurred.
     *
     * @note The write_some operation may not transmit all of the data to the
     * peer. Consider using the @ref write_at function if you need to ensure that
     * all data is written before the blocking operation completes.
     */
    template <typename ConstBufferSequence>
    std::size_t write_some_at(uint64_t offset,
        const ConstBufferSequence& buffers, boost::system::error_code& ec)
    {
      return this->impl_.get_service().write_some_at(
          this->impl_.get_implementation(), offset, buffers, ec);
    }
  
    /// Start an asynchronous write at the specified offset.
    /**
     * This function is used to asynchronously write data to the random-access
     * handle. The function call always returns immediately.
     *
     * @param offset The offset at which the data will be written.
     *
     * @param buffers One or more data buffers to be written to the handle.
     * 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 handler is called.
     *
     * @param handler The handler to be called when the write operation completes.
     * Copies will be made of the handler as required. The function signature of
     * the handler must be:
     * @code void handler(
     *   const boost::system::error_code& error, // Result of operation.
     *   std::size_t bytes_transferred           // Number of bytes written.
     * ); @endcode
     * Regardless of whether the asynchronous operation completes immediately or
     * not, the 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().
     *
     * @note The write operation may not transmit all of the data to the peer.
     * Consider using the @ref async_write_at function if you need to ensure that
     * all data is written before the asynchronous operation completes.
     *
     * @par Example
     * To write a single data buffer use the @ref buffer function as follows:
     * @code
     * handle.async_write_some_at(42, boost::asio::buffer(data, size), handler);
     * @endcode
     * See the @ref buffer documentation for information on writing multiple
     * buffers in one go, and how to use it with arrays, boost::array or
     * std::vector.
     */
    template <typename ConstBufferSequence, typename WriteHandler>
    BOOST_ASIO_INITFN_RESULT_TYPE(WriteHandler,
        void (boost::system::error_code, std::size_t))
    async_write_some_at(uint64_t offset,
        const ConstBufferSequence& buffers,
        BOOST_ASIO_MOVE_ARG(WriteHandler) handler)
    {
      // If you get an error on the following line it means that your handler does
      // not meet the documented type requirements for a WriteHandler.
      BOOST_ASIO_WRITE_HANDLER_CHECK(WriteHandler, handler) type_check;
  
      boost::asio::async_completion<WriteHandler,
        void (boost::system::error_code, std::size_t)> init(handler);
  
      this->impl_.get_service().async_write_some_at(
          this->impl_.get_implementation(), offset,
          buffers, init.completion_handler,
          this->impl_.get_implementation_executor());
  
      return init.result.get();
    }
  
    /// Read some data from the handle at the specified offset.
    /**
     * This function is used to read data from the random-access handle. The
     * function call will block until one or more bytes of data has been read
     * successfully, or until an error occurs.
     *
     * @param offset The offset at which the data will be read.
     *
     * @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_at 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
     * handle.read_some_at(42, 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_at(uint64_t offset,
        const MutableBufferSequence& buffers)
    {
      boost::system::error_code ec;
      std::size_t s = this->impl_.get_service().read_some_at(
          this->impl_.get_implementation(), offset, buffers, ec);
      boost::asio::detail::throw_error(ec, "read_some_at");
      return s;
    }
  
    /// Read some data from the handle at the specified offset.
    /**
     * This function is used to read data from the random-access handle. The
     * function call will block until one or more bytes of data has been read
     * successfully, or until an error occurs.
     *
     * @param offset The offset at which the data will be read.
     *
     * @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_at 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_at(uint64_t offset,
        const MutableBufferSequence& buffers, boost::system::error_code& ec)
    {
      return this->impl_.get_service().read_some_at(
          this->impl_.get_implementation(), offset, buffers, ec);
    }
  
    /// Start an asynchronous read at the specified offset.
    /**
     * This function is used to asynchronously read data from the random-access
     * handle. The function call always returns immediately.
     *
     * @param offset The offset at which the data will be read.
     *
     * @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 handler is called.
     *
     * @param handler The handler to be called when the read operation completes.
     * Copies will be made of the handler as required. The function signature of
     * the 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 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().
     *
     * @note The read operation may not read all of the requested number of bytes.
     * Consider using the @ref async_read_at 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
     * handle.async_read_some_at(42, 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, typename ReadHandler>
    BOOST_ASIO_INITFN_RESULT_TYPE(ReadHandler,
        void (boost::system::error_code, std::size_t))
    async_read_some_at(uint64_t offset,
        const MutableBufferSequence& buffers,
        BOOST_ASIO_MOVE_ARG(ReadHandler) handler)
    {
      // 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;
  
      boost::asio::async_completion<ReadHandler,
        void (boost::system::error_code, std::size_t)> init(handler);
  
      this->impl_.get_service().async_read_some_at(
          this->impl_.get_implementation(), offset,
          buffers, init.completion_handler,
          this->impl_.get_implementation_executor());
  
      return init.result.get();
    }
  };
  
  } // namespace windows
  } // namespace asio
  } // namespace boost
  
  #include <boost/asio/detail/pop_options.hpp>
  
  #endif // defined(BOOST_ASIO_HAS_WINDOWS_RANDOM_ACCESS_HANDLE)
         //   || defined(GENERATING_DOCUMENTATION)
  
  #endif // BOOST_ASIO_WINDOWS_BASIC_RANDOM_ACCESS_HANDLE_HPP
  