an be <a href="../example/fundamental/subrule_calc.cpp">viewed 
  here</a>. This is part of the Spirit distribution. </p>
<table border="0" align="left">
  <tr> 
    <td width="199"><img src="theme/subrule1.png" width="234" height="224"></td>
    <td width="2"></td>
  </tr>
</table>
<p>The subrule as an efficient version of the rule. Compiler optimizations such
  as aggressive inlining help reduce the code size and increase performance significantly.
</p>
<p>The subrule is not a panacea however. Subrules pu