The BOOST_PP_LIST_APPEND_D macro appends two lists.  It reenters BOOST_PP_WHILE with maximum efficiency.

Usage

BOOST_PP_LIST_APPEND_D(d, a, b)

Arguments

d
The next available BOOST_PP_WHILE iteration.
a
The first list.
b
The second list.

Remarks

This macro appends two lists.  For example, if a is (1, (2, (3, BOOST_PP_NIL))) and b is (4, (5, BOOST_PP_NIL)), this macro will expand to:
(1, (2, (3, (4, (5, BOOST_PP_NIL)))))

See Also

Requirements

Header:  <boost/preprocessor/list/append.hpp>

Sample Code

#include <boost/preprocessor/arithmetic/dec.hpp>
#include <boost/preprocessor/control/while.hpp>
#include <boost/preprocessor/list/append.hpp>
#include <boost/preprocessor/tuple/elem.hpp>

#define LIST (1, (2, (3, BOOST_PP_NIL)))

#define PRED(d, state) BOOST_PP_TUPLE_ELEM(3, 1, state)

#define OP(d, state) /* .................. */ \
   (                                          \
      BOOST_PP_LIST_APPEND_D(                 \
         d, BOOST_PP_TUPLE_ELEM(3, 0, state), \
         BOOST_PP_TUPLE_ELEM(3, 2, state)     \
      ),                                      \
      BOOST_PP_DEC(                           \
         BOOST_PP_TUPLE_ELEM(3, 1, state)     \
      ),                                      \
      BOOST_PP_TUPLE_ELEM(3, 2, state)        \
   )                                          \
   /**/

#define LIST_MULTIPLY(c, list) /* ... */ \
   BOOST_PP_TUPLE_ELEM(                  \
      3, 0,                              \
      BOOST_PP_WHILE(                    \
         PRED, OP,                       \
         (BOOST_PP_NIL, c, list)         \
      )                                  \
   )                                     \
   /**/

LIST_MULTIPLY(3, LIST)
   // expands to (1, (2, (3, (1, (2, (3, (1, (2, (3, BOOST_PP_NIL)))))))))