The BOOST_PP_LIST_FOR_EACH_PRODUCT macro repeats a macro for each cartesian product of several lists.
Usage
BOOST_PP_LIST_FOR_EACH_PRODUCT(macro, size, tuple)
Arguments
- macro
-
The binary macro of the form macro(r, product).
This macro is expanded by BOOST_PP_FOR_EACH_PRODUCT with each cartesian product in tuple.
It is expanded with the next available BOOST_PP_FOR repetition and a tuple containing a cartesian product.
This tuple will have size elements.
- size
-
The size of tuple.
- tuple
-
A tuple of lists from which cartesian products are obtained.
Remarks
This macro is a repetition construct.
If two
lists are (
a, (
b, (
c,
BOOST_PP_NIL))) and (
x, (
y, (
z,
BOOST_PP_NIL))),
this macro will produce the following sequence:
macro(r, (a, x))
macro(r, (a, y))
macro(r, (a, z))
macro(r, (b, x))
macro(r, (b, y))
macro(r, (b, z))
macro(r, (c, x))
macro(r, (c, y))
macro(r, (c, z))
Previously, this macro could not be used inside BOOST_PP_FOR.
There is no longer any such restriction.
It is more efficient, however, to use BOOST_PP_LIST_FOR_EACH_PRODUCT_R in such a situation.
See Also
Requirements
Sample Code
#include <boost/preprocessor/list/for_each_product.hpp>
#define L1 (a, (b, (c, BOOST_PP_NIL)))
#define L2 (x, (y, (z, BOOST_PP_NIL)))
#define MACRO(r, product) product
BOOST_PP_LIST_FOR_EACH_PRODUCT(MACRO, 2, (L1, L2))
// expands to (a, x) (a, y) (a, z) (b, x) (b, y) (b, z) (c, x) (c, y) (c, z)