text: //
  // detail/winrt_ssocket_service_base.hpp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2015 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_DETAIL_WINRT_SSOCKET_SERVICE_BASE_HPP
  #define ASIO_DETAIL_WINRT_SSOCKET_SERVICE_BASE_HPP
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  # pragma once
  #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  
  #include "asio/detail/config.hpp"
  
  #if defined(ASIO_WINDOWS_RUNTIME)
  
  #include "asio/buffer.hpp"
  #include "asio/error.hpp"
  #include "asio/io_service.hpp"
  #include "asio/socket_base.hpp"
  #include "asio/detail/addressof.hpp"
  #include "asio/detail/buffer_sequence_adapter.hpp"
  #include "asio/detail/socket_types.hpp"
  #include "asio/detail/winrt_async_manager.hpp"
  #include "asio/detail/winrt_socket_recv_op.hpp"
  #include "asio/detail/winrt_socket_send_op.hpp"
  
  #include "asio/detail/push_options.hpp"
  
  namespace asio {
  namespace detail {
  
  class winrt_ssocket_service_base
  {
  public:
    // The native type of a socket.
    typedef Windows::Networking::Sockets::StreamSocket^ native_handle_type;
  
    // The implementation type of the socket.
    struct base_implementation_type
    {
      // Default constructor.
      base_implementation_type()
        : socket_(nullptr),
          next_(0),
          prev_(0)
      {
      }
  
      // The underlying native socket.
      native_handle_type socket_;
  
      // Pointers to adjacent socket implementations in linked list.
      base_implementation_type* next_;
      base_implementation_type* prev_;
    };
  
    // Constructor.
    ASIO_DECL winrt_ssocket_service_base(
        asio::io_service& io_service);
  
    // Destroy all user-defined handler objects owned by the service.
    ASIO_DECL void shutdown_service();
  
    // Construct a new socket implementation.
    ASIO_DECL void construct(base_implementation_type&);
  
    // Move-construct a new socket implementation.
    ASIO_DECL void base_move_construct(base_implementation_type& impl,
        base_implementation_type& other_impl);
  
    // Move-assign from another socket implementation.
    ASIO_DECL void base_move_assign(base_implementation_type& impl,
        winrt_ssocket_service_base& other_service,
        base_implementation_type& other_impl);
  
    // Destroy a socket implementation.
    ASIO_DECL void destroy(base_implementation_type& impl);
  
    // Determine whether the socket is open.
    bool is_open(const base_implementation_type& impl) const
    {
      return impl.socket_ != nullptr;
    }
  
    // Destroy a socket implementation.
    ASIO_DECL asio::error_code close(
        base_implementation_type& impl, asio::error_code& ec);
  
    // Get the native socket representation.
    native_handle_type native_handle(base_implementation_type& impl)
    {
      return impl.socket_;
    }
  
    // Cancel all operations associated with the socket.
    asio::error_code cancel(base_implementation_type&,
        asio::error_code& ec)
    {
      ec = asio::error::operation_not_supported;
      return ec;
    }
  
    // Determine whether the socket is at the out-of-band data mark.
    bool at_mark(const base_implementation_type&,
        asio::error_code& ec) const
    {
      ec = asio::error::operation_not_supported;
      return false;
    }
  
    // Determine the number of bytes available for reading.
    std::size_t available(const base_implementation_type&,
        asio::error_code& ec) const
    {
      ec = asio::error::operation_not_supported;
      return 0;
    }
  
    // Perform an IO control command on the socket.
    template <typename IO_Control_Command>
    asio::error_code io_control(base_implementation_type&,
        IO_Control_Command&, asio::error_code& ec)
    {
      ec = asio::error::operation_not_supported;
      return ec;
    }
  
    // Gets the non-blocking mode of the socket.
    bool non_blocking(const base_implementation_type&) const
    {
      return false;
    }
  
    // Sets the non-blocking mode of the socket.
    asio::error_code non_blocking(base_implementation_type&,
        bool, asio::error_code& ec)
    {
      ec = asio::error::operation_not_supported;
      return ec;
    }
  
    // Gets the non-blocking mode of the native socket implementation.
    bool native_non_blocking(const base_implementation_type&) const
    {
      return false;
    }
  
    // Sets the non-blocking mode of the native socket implementation.
    asio::error_code native_non_blocking(base_implementation_type&,
        bool, asio::error_code& ec)
    {
      ec = asio::error::operation_not_supported;
      return ec;
    }
  
    // Disable sends or receives on the socket.
    asio::error_code shutdown(base_implementation_type&,
        socket_base::shutdown_type, asio::error_code& ec)
    {
      ec = asio::error::operation_not_supported;
      return ec;
    }
  
    // Send the given data to the peer.
    template <typename ConstBufferSequence>
    std::size_t send(base_implementation_type& impl,
        const ConstBufferSequence& buffers,
        socket_base::message_flags flags, asio::error_code& ec)
    {
      return do_send(impl,
          buffer_sequence_adapter<asio::const_buffer,
            ConstBufferSequence>::first(buffers), flags, ec);
    }
  
    // Wait until data can be sent without blocking.
    std::size_t send(base_implementation_type&, const null_buffers&,
        socket_base::message_flags, asio::error_code& ec)
    {
      ec = asio::error::operation_not_supported;
      return 0;
    }
  
    // Start an asynchronous send. The data being sent must be valid for the
    // lifetime of the asynchronous operation.
    template <typename ConstBufferSequence, typename Handler>
    void async_send(base_implementation_type& impl,
        const ConstBufferSequence& buffers,
        socket_base::message_flags flags, Handler& handler)
    {
      bool is_continuation =
        asio_handler_cont_helpers::is_continuation(handler);
  
      // Allocate and construct an operation to wrap the handler.
      typedef winrt_socket_send_op<ConstBufferSequence, Handler> op;
      typename op::ptr p = { asio::detail::addressof(handler),
        asio_handler_alloc_helpers::allocate(
          sizeof(op), handler), 0 };
      p.p = new (p.v) op(buffers, handler);
  
      ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_send"));
  
      start_send_op(impl,
          buffer_sequence_adapter<asio::const_buffer,
            ConstBufferSequence>::first(buffers),
          flags, p.p, is_continuation);
      p.v = p.p = 0;
    }
  
    // Start an asynchronous wait until data can be sent without blocking.
    template <typename Handler>
    void async_send(base_implementation_type&, const null_buffers&,
        socket_base::message_flags, Handler& handler)
    {
      asio::error_code ec = asio::error::operation_not_supported;
      const std::size_t bytes_transferred = 0;
      io_service_.get_io_service().post(
          detail::bind_handler(handler, ec, bytes_transferred));
    }
  
    // Receive some data from the peer. Returns the number of bytes received.
    template <typename MutableBufferSequence>
    std::size_t receive(base_implementation_type& impl,
        const MutableBufferSequence& buffers,
        socket_base::message_flags flags, asio::error_code& ec)
    {
      return do_receive(impl,
          buffer_sequence_adapter<asio::mutable_buffer,
            MutableBufferSequence>::first(buffers), flags, ec);
    }
  
    // Wait until data can be received without blocking.
    std::size_t receive(base_implementation_type&, const null_buffers&,
        socket_base::message_flags, asio::error_code& ec)
    {
      ec = asio::error::operation_not_supported;
      return 0;
    }
  
    // Start an asynchronous receive. The buffer for the data being received
    // must be valid for the lifetime of the asynchronous operation.
    template <typename MutableBufferSequence, typename Handler>
    void async_receive(base_implementation_type& impl,
        const MutableBufferSequence& buffers,
        socket_base::message_flags flags, Handler& handler)
    {
      bool is_continuation =
        asio_handler_cont_helpers::is_continuation(handler);
  
      // Allocate and construct an operation to wrap the handler.
      typedef winrt_socket_recv_op<MutableBufferSequence, Handler> op;
      typename op::ptr p = { asio::detail::addressof(handler),
        asio_handler_alloc_helpers::allocate(
          sizeof(op), handler), 0 };
      p.p = new (p.v) op(buffers, handler);
  
      ASIO_HANDLER_CREATION((p.p, "socket", &impl, "async_receive"));
  
      start_receive_op(impl,
          buffer_sequence_adapter<asio::mutable_buffer,
            MutableBufferSequence>::first(buffers),
          flags, p.p, is_continuation);
      p.v = p.p = 0;
    }
  
    // Wait until data can be received without blocking.
    template <typename Handler>
    void async_receive(base_implementation_type&, const null_buffers&,
        socket_base::message_flags, Handler& handler)
    {
      asio::error_code ec = asio::error::operation_not_supported;
      const std::size_t bytes_transferred = 0;
      io_service_.get_io_service().post(
          detail::bind_handler(handler, ec, bytes_transferred));
    }
  
  protected:
    // Helper function to obtain endpoints associated with the connection.
    ASIO_DECL std::size_t do_get_endpoint(
        const base_implementation_type& impl, bool local,
        void* addr, std::size_t addr_len, asio::error_code& ec) const;
  
    // Helper function to set a socket option.
    ASIO_DECL asio::error_code do_set_option(
        base_implementation_type& impl,
        int level, int optname, const void* optval,
        std::size_t optlen, asio::error_code& ec);
  
    // Helper function to get a socket option.
    ASIO_DECL void do_get_option(
        const base_implementation_type& impl,
        int level, int optname, void* optval,
        std::size_t* optlen, asio::error_code& ec) const;
  
    // Helper function to perform a synchronous connect.
    ASIO_DECL asio::error_code do_connect(
        base_implementation_type& impl,
        const void* addr, asio::error_code& ec);
  
    // Helper function to start an asynchronous connect.
    ASIO_DECL void start_connect_op(
        base_implementation_type& impl, const void* addr,
        winrt_async_op<void>* op, bool is_continuation);
  
    // Helper function to perform a synchronous send.
    ASIO_DECL std::size_t do_send(
        base_implementation_type& impl, const asio::const_buffer& data,
        socket_base::message_flags flags, asio::error_code& ec);
  
    // Helper function to start an asynchronous send.
    ASIO_DECL void start_send_op(base_implementation_type& impl,
        const asio::const_buffer& data, socket_base::message_flags flags,
        winrt_async_op<unsigned int>* op, bool is_continuation);
  
    // Helper function to perform a synchronous receive.
    ASIO_DECL std::size_t do_receive(
        base_implementation_type& impl, const asio::mutable_buffer& data,
        socket_base::message_flags flags, asio::error_code& ec);
  
    // Helper function to start an asynchronous receive.
    ASIO_DECL void start_receive_op(base_implementation_type& impl,
        const asio::mutable_buffer& data, socket_base::message_flags flags,
        winrt_async_op<Windows::Storage::Streams::IBuffer^>* op,
        bool is_continuation);
  
    // The io_service implementation used for delivering completions.
    io_service_impl& io_service_;
  
    // The manager that keeps track of outstanding operations.
    winrt_async_manager& async_manager_;
  
    // Mutex to protect access to the linked list of implementations. 
    asio::detail::mutex mutex_;
  
    // The head of a linked list of all implementations.
    base_implementation_type* impl_list_;
  };
  
  } // namespace detail
  } // namespace asio
  
  #include "asio/detail/pop_options.hpp"
  
  #if defined(ASIO_HEADER_ONLY)
  # include "asio/detail/impl/winrt_ssocket_service_base.ipp"
  #endif // defined(ASIO_HEADER_ONLY)
  
  #endif // defined(ASIO_WINDOWS_RUNTIME)
  
  #endif // ASIO_DETAIL_WINRT_SSOCKET_SERVICE_BASE_HPP
  