attribute_type</span><span class="special">&amp;)</span></code> or expose a member function
              <code class="computeroutput"><span class="identifier">attribute_type</span><span class="special">::</span><span class="identifier">swap</span><span class="special">(</span><span class="identifier">attribute_type</span><span class="special">&amp;)</span></code>.
            </p></td></tr>
</table></div>
<h6>
<a name="spirit.qi.reference.directive.hold.h6"></a>
            <span class="phrase"><a name="sp