The BOOST_PP_LIST_TRANSFORM macro transforms each element in a list according to a supplied transformation.
Usage
BOOST_PP_LIST_TRANSFORM(op, data, list)
Arguments
- op
-
A ternary predicate of the form op(d, data, elem).
This transformation is expanded by BOOST_PP_LIST_TRANSFORM for each element in list with the next available BOOST_PP_WHILE iteration,
the auxiliary data, and the current element in list.
- data
-
Auxiliary data passed to pred.
- list
-
The list to be transformed.
Remarks
This macro expands
op for each element in
list.
It builds a new
list out of the results of each call.
If, for example,
list is (
a, (
b, (
c,
BOOST_PP_NIL))),
this macro expands to...
(op(d, data, a), (op(d, data, b), (op(d, data, c), BOOST_PP_NIL)))
Previously, this macro could not be used inside BOOST_PP_WHILE.
There is no longer any such restriction.
It is more efficient, however, to use BOOST_PP_LIST_TRANSFORM_D in such a situation.
See Also
Requirements
Sample Code
#include <boost/preprocessor/arithmetic/dec.hpp>
#include <boost/preprocessor/list/transform.hpp>
#define LIST (1, (3, (2, (5, BOOST_PP_NIL))))
#define OP(d, data, elem) BOOST_PP_DEC(elem)
BOOST_PP_LIST_TRANSFORM(OP, 3, LIST)
// expands to (0, (2, (1, (4, BOOST_PP_NIL))))