lExpNodePtr">xmlExpNodePtr</a>	xmlExpExpDerive		(<a href="libxml2-xmlregexp.html#xmlExpCtxtPtr">xmlExpCtxtPtr</a> ctxt, <br/>					 <a href="libxml2-xmlregexp.html#xmlExpNodePtr">xmlExpNodePtr</a> exp, <br/>					 <a href="libxml2-xmlregexp.html#xmlExpNodePtr">xmlExpNodePtr</a> sub)<br/>
</pre><p>Evaluates the expression resulting from @exp consuming a sub expression @sub Based on algebraic derivation and sometimes direct Brzozowski derivation it usually tatkes less than linear time and can handle expression