herit from the base template class, parser:</p>
<pre>
<span class=keyword>template </span><span class=special>&lt;</span><span class=keyword>typename </span><span class=identifier>DerivedT</span><span class=special>&gt;
</span><span class=keyword>struct </span><span class=identifier>parser
</span><span class=special>{
    </span><span class=comment>/*...*/

    </span><span class=identifier>DerivedT</span><span class=special>&amp; </span><span class=identifier>derived</span><span class=special>();
    </spa