text: //
  // detail/descriptor_write_op.hpp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2017 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_DETAIL_DESCRIPTOR_WRITE_OP_HPP
  #define BOOST_ASIO_DETAIL_DESCRIPTOR_WRITE_OP_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_WINDOWS) && !defined(__CYGWIN__)
  
  #include <boost/asio/detail/bind_handler.hpp>
  #include <boost/asio/detail/buffer_sequence_adapter.hpp>
  #include <boost/asio/detail/descriptor_ops.hpp>
  #include <boost/asio/detail/fenced_block.hpp>
  #include <boost/asio/detail/handler_work.hpp>
  #include <boost/asio/detail/memory.hpp>
  #include <boost/asio/detail/reactor_op.hpp>
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  namespace detail {
  
  template <typename ConstBufferSequence>
  class descriptor_write_op_base : public reactor_op
  {
  public:
    descriptor_write_op_base(int descriptor,
        const ConstBufferSequence& buffers, func_type complete_func)
      : reactor_op(&descriptor_write_op_base::do_perform, complete_func),
        descriptor_(descriptor),
        buffers_(buffers)
    {
    }
  
    static status do_perform(reactor_op* base)
    {
      descriptor_write_op_base* o(static_cast<descriptor_write_op_base*>(base));
  
      buffer_sequence_adapter<boost::asio::const_buffer,
          ConstBufferSequence> bufs(o->buffers_);
  
      status result = descriptor_ops::non_blocking_write(o->descriptor_,
          bufs.buffers(), bufs.count(), o->ec_, o->bytes_transferred_)
        ? done : not_done;
  
      BOOST_ASIO_HANDLER_REACTOR_OPERATION((*o, "non_blocking_write",
            o->ec_, o->bytes_transferred_));
  
      return result;
    }
  
  private:
    int descriptor_;
    ConstBufferSequence buffers_;
  };
  
  template <typename ConstBufferSequence, typename Handler>
  class descriptor_write_op
    : public descriptor_write_op_base<ConstBufferSequence>
  {
  public:
    BOOST_ASIO_DEFINE_HANDLER_PTR(descriptor_write_op);
  
    descriptor_write_op(int descriptor,
        const ConstBufferSequence& buffers, Handler& handler)
      : descriptor_write_op_base<ConstBufferSequence>(
          descriptor, buffers, &descriptor_write_op::do_complete),
        handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
    {
      handler_work<Handler>::start(handler_);
    }
  
    static void do_complete(void* owner, operation* base,
        const boost::system::error_code& /*ec*/,
        std::size_t /*bytes_transferred*/)
    {
      // Take ownership of the handler object.
      descriptor_write_op* o(static_cast<descriptor_write_op*>(base));
      ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
      handler_work<Handler> w(o->handler_);
  
      BOOST_ASIO_HANDLER_COMPLETION((*o));
  
      // Make a copy of the handler so that the memory can be deallocated before
      // the upcall is made. Even if we're not about to make an upcall, a
      // sub-object of the handler may be the true owner of the memory associated
      // with the handler. Consequently, a local copy of the handler is required
      // to ensure that any owning sub-object remains valid until after we have
      // deallocated the memory here.
      detail::binder2<Handler, boost::system::error_code, std::size_t>
        handler(o->handler_, o->ec_, o->bytes_transferred_);
      p.h = boost::asio::detail::addressof(handler.handler_);
      p.reset();
  
      // Make the upcall if required.
      if (owner)
      {
        fenced_block b(fenced_block::half);
        BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
        w.complete(handler, handler.handler_);
        BOOST_ASIO_HANDLER_INVOCATION_END;
      }
    }
  
  private:
    Handler handler_;
  };
  
  } // namespace detail
  } // namespace asio
  } // namespace boost
  
  #include <boost/asio/detail/pop_options.hpp>
  
  #endif // !defined(BOOST_ASIO_WINDOWS) && !defined(__CYGWIN__)
  
  #endif // BOOST_ASIO_DETAIL_DESCRIPTOR_WRITE_OP_HPP
  