#include <boost/preprocessor/comparison/less_equal.hpp> #include <boost/preprocessor/list/filter.hpp> #include <boost/preprocessor/list/fold_right.hpp> #define A (1, (2, (3, (4, BOOST_PP_NIL)))) #define B (A, (A, (A, (A, BOOST_PP_NIL)))) #define PRED(d, data, x) BOOST_PP_LESS_EQUAL(x, data) #define OP(d, state, x) (BOOST_PP_LIST_FILTER_D(d, PRED, 2, x), state) BOOST_PP_LIST_FOLD_RIGHT(OP, BOOST_PP_NIL, B) /* expands to: ((1, (2, BOOST_PP_NIL)), ((1, (2, BOOST_PP_NIL)), ((1, (2, BOOST_PP_NIL)), ((1, (2, BOOST_PP_NIL)), BOOST_PP_NIL)))) */