void operator()

in demo_example/asio/asio/ssl/detail/io.hpp [145:320]
103 lines of code
18 McCabe index (conditional complexity)

  void operator()(asio::error_code ec,
      std::size_t bytes_transferred = ~std::size_t(0), int start = 0)
  {
    switch (start_ = start)
    {
    case 1: // Called after at least one async operation.
      do
      {
        switch (want_ = op_(core_.engine_, ec_, bytes_transferred_))
        {
        case engine::want_input_and_retry:

          // If the input buffer already has data in it we can pass it to the
          // engine and then retry the operation immediately.
          if (core_.input_.size() != 0)
          {
            core_.input_ = core_.engine_.put_input(core_.input_);
            continue;
          }

          // The engine wants more data to be read from input. However, we
          // cannot allow more than one read operation at a time on the
          // underlying transport. The pending_read_ timer's expiry is set to
          // pos_infin if a read is in progress, and neg_infin otherwise.
          if (core_.expiry(core_.pending_read_) == core_.neg_infin())
          {
            // Prevent other read operations from being started.
            core_.pending_read_.expires_at(core_.pos_infin());

            ASIO_HANDLER_LOCATION((
                  __FILE__, __LINE__, Operation::tracking_name()));

            // Start reading some data from the underlying transport.
            next_layer_.async_read_some(
                asio::buffer(core_.input_buffer_),
                ASIO_MOVE_CAST(io_op)(*this));
          }
          else
          {
            ASIO_HANDLER_LOCATION((
                  __FILE__, __LINE__, Operation::tracking_name()));

            // Wait until the current read operation completes.
            core_.pending_read_.async_wait(ASIO_MOVE_CAST(io_op)(*this));
          }

          // Yield control until asynchronous operation completes. Control
          // resumes at the "default:" label below.
          return;

        case engine::want_output_and_retry:
        case engine::want_output:

          // The engine wants some data to be written to the output. However, we
          // cannot allow more than one write operation at a time on the
          // underlying transport. The pending_write_ timer's expiry is set to
          // pos_infin if a write is in progress, and neg_infin otherwise.
          if (core_.expiry(core_.pending_write_) == core_.neg_infin())
          {
            // Prevent other write operations from being started.
            core_.pending_write_.expires_at(core_.pos_infin());

            ASIO_HANDLER_LOCATION((
                  __FILE__, __LINE__, Operation::tracking_name()));

            // Start writing all the data to the underlying transport.
            asio::async_write(next_layer_,
                core_.engine_.get_output(core_.output_buffer_),
                ASIO_MOVE_CAST(io_op)(*this));
          }
          else
          {
            ASIO_HANDLER_LOCATION((
                  __FILE__, __LINE__, Operation::tracking_name()));

            // Wait until the current write operation completes.
            core_.pending_write_.async_wait(ASIO_MOVE_CAST(io_op)(*this));
          }

          // Yield control until asynchronous operation completes. Control
          // resumes at the "default:" label below.
          return;

        default:

          // The SSL operation is done and we can invoke the handler, but we
          // have to keep in mind that this function might be being called from
          // the async operation's initiating function. In this case we're not
          // allowed to call the handler directly. Instead, issue a zero-sized
          // read so the handler runs "as-if" posted using io_context::post().
          if (start)
          {
            ASIO_HANDLER_LOCATION((
                  __FILE__, __LINE__, Operation::tracking_name()));

            next_layer_.async_read_some(
                asio::buffer(core_.input_buffer_, 0),
                ASIO_MOVE_CAST(io_op)(*this));

            // Yield control until asynchronous operation completes. Control
            // resumes at the "default:" label below.
            return;
          }
          else
          {
            // Continue on to run handler directly.
            break;
          }
        }

        default:
        if (bytes_transferred == ~std::size_t(0))
          bytes_transferred = 0; // Timer cancellation, no data transferred.
        else if (!ec_)
          ec_ = ec;

        switch (want_)
        {
        case engine::want_input_and_retry:

          // Add received data to the engine's input.
          core_.input_ = asio::buffer(
              core_.input_buffer_, bytes_transferred);
          core_.input_ = core_.engine_.put_input(core_.input_);

          // Release any waiting read operations.
          core_.pending_read_.expires_at(core_.neg_infin());

          // Check for cancellation before continuing.
          if (this->cancelled() != cancellation_type::none)
          {
            ec_ = asio::error::operation_aborted;
            break;
          }

          // Try the operation again.
          continue;

        case engine::want_output_and_retry:

          // Release any waiting write operations.
          core_.pending_write_.expires_at(core_.neg_infin());

          // Check for cancellation before continuing.
          if (this->cancelled() != cancellation_type::none)
          {
            ec_ = asio::error::operation_aborted;
            break;
          }

          // Try the operation again.
          continue;

        case engine::want_output:

          // Release any waiting write operations.
          core_.pending_write_.expires_at(core_.neg_infin());

          // Fall through to call handler.

        default:

          // Pass the result to the handler.
          op_.call_handler(handler_,
              core_.engine_.map_error_code(ec_),
              ec_ ? 0 : bytes_transferred_);

          // Our work here is done.
          return;
        }
      } while (!ec_);

      // Operation failed. Pass the result to the handler.
      op_.call_handler(handler_, core_.engine_.map_error_code(ec_), 0);
    }
  }