O(r, state) \
   <a href="comma_if.html">BOOST_PP_COMMA_IF</a>( \
      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 3, state) \
   ) template&lt; \
      <a href="for_r.html">BOOST_PP_FOR_</a> ## r( \
         (0, <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, state), _, 0), \
         PRED_2, OP, MACRO_2 \
      ) \
   &gt; class <a href="cat.html">BOOST_PP_CAT</a>( \
      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 2, state), \
      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELE