text: //
  // detail/resolve_endpoint_op.hpp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2016 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_RESOLVER_ENDPOINT_OP_HPP
  #define BOOST_ASIO_DETAIL_RESOLVER_ENDPOINT_OP_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/error.hpp>
  #include <boost/asio/io_service.hpp>
  #include <boost/asio/ip/basic_resolver_iterator.hpp>
  #include <boost/asio/detail/addressof.hpp>
  #include <boost/asio/detail/bind_handler.hpp>
  #include <boost/asio/detail/fenced_block.hpp>
  #include <boost/asio/detail/handler_alloc_helpers.hpp>
  #include <boost/asio/detail/handler_invoke_helpers.hpp>
  #include <boost/asio/detail/operation.hpp>
  #include <boost/asio/detail/socket_ops.hpp>
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  namespace detail {
  
  template <typename Protocol, typename Handler>
  class resolve_endpoint_op : public operation
  {
  public:
    BOOST_ASIO_DEFINE_HANDLER_PTR(resolve_endpoint_op);
  
    typedef typename Protocol::endpoint endpoint_type;
    typedef boost::asio::ip::basic_resolver_iterator<Protocol> iterator_type;
  
    resolve_endpoint_op(socket_ops::weak_cancel_token_type cancel_token,
        const endpoint_type& endpoint, io_service_impl& ios, Handler& handler)
      : operation(&resolve_endpoint_op::do_complete),
        cancel_token_(cancel_token),
        endpoint_(endpoint),
        io_service_impl_(ios),
        handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler))
    {
    }
  
    static void do_complete(io_service_impl* owner, operation* base,
        const boost::system::error_code& /*ec*/,
        std::size_t /*bytes_transferred*/)
    {
      // Take ownership of the operation object.
      resolve_endpoint_op* o(static_cast<resolve_endpoint_op*>(base));
      ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
  
      if (owner && owner != &o->io_service_impl_)
      {
        // The operation is being run on the worker io_service. Time to perform
        // the resolver operation.
      
        // Perform the blocking endpoint resolution operation.
        char host_name[NI_MAXHOST];
        char service_name[NI_MAXSERV];
        socket_ops::background_getnameinfo(o->cancel_token_, o->endpoint_.data(),
            o->endpoint_.size(), host_name, NI_MAXHOST, service_name, NI_MAXSERV,
            o->endpoint_.protocol().type(), o->ec_);
        o->iter_ = iterator_type::create(o->endpoint_, host_name, service_name);
  
        // Pass operation back to main io_service for completion.
        o->io_service_impl_.post_deferred_completion(o);
        p.v = p.p = 0;
      }
      else
      {
        // The operation has been returned to the main io_service. The completion
        // handler is ready to be delivered.
  
        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, iterator_type>
          handler(o->handler_, o->ec_, o->iter_);
        p.h = boost::asio::detail::addressof(handler.handler_);
        p.reset();
  
        if (owner)
        {
          fenced_block b(fenced_block::half);
          BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, "..."));
          boost_asio_handler_invoke_helpers::invoke(handler, handler.handler_);
          BOOST_ASIO_HANDLER_INVOCATION_END;
        }
      }
    }
  
  private:
    socket_ops::weak_cancel_token_type cancel_token_;
    endpoint_type endpoint_;
    io_service_impl& io_service_impl_;
    Handler handler_;
    boost::system::error_code ec_;
    iterator_type iter_;
  };
  
  } // namespace detail
  } // namespace asio
  } // namespace boost
  
  #include <boost/asio/detail/pop_options.hpp>
  
  #endif // BOOST_ASIO_DETAIL_RESOLVER_ENDPOINT_OP_HPP
  