The BOOST_PP_SET_FOLD_RIGHT macro folds (or accumulates) the elements of a set right-to-left.

Usage

BOOST_PP_SET_FOLD_RIGHT(op, state, set)

Arguments

op
A ternary operation of the form op(s, state, elem).  This macro is called for each element in set--each time returning a new state.  This operation is expanded by BOOST_PP_SET_FOLD_RIGHT with the next available fold step, the current state, and the current element.
state
The initial state of the fold.
set
The set to be folded.

Remarks

For the set, (0)(1)(2), this macro expands to:
op(s, op(s, op(s, state, 2), 1), 0)
For maximum efficiency, BOOST_PP_SET_FOLD_RIGHT can be reentered with BOOST_PP_SET_FOLD_RIGHT_s.

See Also

Requirements

Header:  <boost/preprocessor/set/fold_right.hpp>

Sample Code

#include <boost/preprocessor/cat.hpp>
#include <boost/preprocessor/set/elem.hpp>
#include <boost/preprocessor/set/fold_right.hpp>
#include <boost/preprocessor/set/pop_back.hpp>

#define SET (t)(s)(o)(o)(b)

#define OP(s, state, x) BOOST_PP_CAT(state, x)

BOOST_PP_SET_FOLD_RIGHT(OP, BOOST_PP_SET_ELEM(4, SET), BOOST_PP_SET_POP_BACK(SET)) // expands to boost