n><span class=identifier>DerivedT </span><span class=keyword>const</span><span class=special>&amp; </span><span class=identifier>derived</span><span class=special>() </span><span class=keyword>const</span><span class=special>;
</span><span class=special>};</span></pre>
<p>This class is a protocol base class for all parsers. The parser class does 
  not really know how to parse anything but instead relies on the template parameter 
  <tt>DerivedT</tt> to do the actual parsing. This technique is known as the 