I created a macro taking 3 conditions (as example, 8 in my real case):
#define FOO(A,B,C) \
BOOST_PP_IF(A, a1, a2) \
BOOST_PP_IF(B, b1, b2) \
BOOST_PP_IF(C, c1, c2)
This works as I expect. Now I want to expand all the possibilities:
FOO(0,0,0)
FOO(0,0,1)
FOO(0,1,0)
FOO(0,1,1)
FOO(1,0,0)
FOO(1,0,1)
FOO(1,1,0)
FOO(1,1,1)
By this way, I have to write 8 lines. In my real case, I have to write 256 lines.
How can I generate it directly with (boost) preprocessor tools ?
MCV example with constructors declaration of a class Foo
close to my real problem:
#define WRITE_FOO(A,B,C) \
Foo(int a1 BOOST_PP_COMMA_IF(A) BOOST_PP_IF(A, int a2, BOOST_PP_EMPTY()),
double b1 BOOST_PP_COMMA_IF(B) BOOST_PP_IF(B, double b2, BOOST_PP_EMPTY()),
bool c1 BOOST_PP_COMMA_IF(C) BOOST_PP_IF(C, bool c2, BOOST_PP_EMPTY()));
Then
class Foo {
public:
WRITE_FOO(0,0,0)
WRITE_FOO(0,0,1)
WRITE_FOO(0,1,0)
WRITE_FOO(0,1,1)
WRITE_FOO(1,0,0)
WRITE_FOO(1,0,1)
WRITE_FOO(1,1,0)
WRITE_FOO(1,1,1)
private:
int a_1;
int a_2;
double b_1;
double b_2;
bool c_1;
bool c_2;
};
is extended to
class Foo {
public:
Foo(int a1, double b1, bool c1);
Foo(int a1, double b1, bool c1, bool c2);
Foo(int a1, double b1, double b2, bool c1);
Foo(int a1, double b1, double b2, bool c1, bool c2);
Foo(int a1, int a2, double b1, bool c1);
Foo(int a1, int a2, double b1, bool c1, bool c2);
Foo(int a1, int a2, double b1, double b2, bool c1);
Foo(int a1, int a2, double b1, double b2, bool c1, bool c2);
private:
int a_1;
int a_2;
double b_1;
double b_2;
bool c_1;
bool c_2;
};
The implementation is similar to:
#define IMPLEMENT_FOO(A,B,C) \
Foo::Foo(int a1 BOOST_PP_COMMA_IF(A) BOOST_PP_IF(A, int a2, BOOST_PP_EMPTY()),
double b1 BOOST_PP_COMMA_IF(B) BOOST_PP_IF(B, double b2, BOOST_PP_EMPTY()),
bool c1 BOOST_PP_COMMA_IF(C) BOOST_PP_IF(C, bool c2, BOOST_PP_EMPTY())): \
a_1(a1), \
a_2(BOOST_PP_IF(A, a2, a1)), \
b_1(b1),
b_2(BOOST_PP_IF(B, b2, b1)), \
c_1(c1),
c_2(BOOST_PP_IF(C, c2, c1)) \
{}
This is a linear-code solution that solves the question (although I would not suggest doing that in real code, use template
s instead if possible)
#define W2(...) W1(__VA_ARGS__,0) W1(__VA_ARGS__,1)
#define W1(...) W0(__VA_ARGS__,0) W0(__VA_ARGS__,1)
W2(0) W2(1)