История изменений
Исправление SZT, (текущая версия) :
Вот решение на основе старого макроговнокода, который я когда-то нагугливал (не уверен что оптимальное)
#define SPLICE(a,b) SPLICE_1(a,b)
#define SPLICE_1(a,b) SPLICE_2(a,b)
#define SPLICE_2(a,b) a##b
#define PP_ARG_N( \
_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, \
_11, _12, _13, _14, _15, _16, _17, _18, _19, _20, \
_21, _22, _23, _24, _25, _26, _27, _28, _29, _30, \
_31, _32, _33, _34, _35, _36, _37, _38, _39, _40, \
_41, _42, _43, _44, _45, _46, _47, _48, _49, _50, \
_51, _52, _53, _54, _55, _56, _57, _58, _59, _60, \
_61, _62, _63, N, ...) N
/* Note 63 is removed */
#define PP_RSEQ_N() \
62, 61, 60, \
59, 58, 57, 56, 55, 54, 53, 52, 51, 50, \
49, 48, 47, 46, 45, 44, 43, 42, 41, 40, \
39, 38, 37, 36, 35, 34, 33, 32, 31, 30, \
29, 28, 27, 26, 25, 24, 23, 22, 21, 20, \
19, 18, 17, 16, 15, 14, 13, 12, 11, 10, \
9, 8, 7, 6, 5, 4, 3, 2, 1, 0
#define PP_NARG_(...) PP_ARG_N(__VA_ARGS__)
#define PP_NARG(...) PP_NARG_(_, ##__VA_ARGS__, PP_RSEQ_N())
#define FIELD_0(...) // NOTHING
#define FIELD_1(field, ...) \
field,
#define FIELD_2(field, ...) \
field, FIELD_1(__VA_ARGS__)
#define FIELD_3(field, ...) \
field, FIELD_2(__VA_ARGS__)
#define FIELD_4(field, ...) \
field, FIELD_3(__VA_ARGS__)
#define FIELD_5(field, ...) \
field, FIELD_4(__VA_ARGS__)
#define FIELD_5(field, ...) \
field, FIELD_4(__VA_ARGS__)
#define FIELD_6(field, ...) \
field, FIELD_5(__VA_ARGS__)
#define FIELD_7(field, ...) \
field, FIELD_6(__VA_ARGS__)
#define FIELD_8(field, ...) \
field, FIELD_7(__VA_ARGS__)
#define FIELD_9(field, ...) \
field, FIELD_8(__VA_ARGS__)
#define FIELD_10(field, ...) \
field, FIELD_9(__VA_ARGS__),
#define FIELD_11(field, ...) \
field, FIELD_10(__VA_ARGS__)
//..... дальше лень ...
#define FIELDS_(N, ...) \
SPLICE(FIELD_, N)(__VA_ARGS__)
#define FIELDS(...) \
FIELDS_(PP_NARG(__VA_ARGS__), __VA_ARGS__)
#define $enable(COND, ARGS...) \
template<FIELDS(ARGS) typename std::enable_if<(COND), int>::type* = nullptr>
$enable(1);
$enable(1, 2);
$enable(1, 2, 3);
$enable(1, 2, 3, 4, 5, 6);
$enable();
template< typename std::enable_if<(1), int>::type* = nullptr>;
template<2, typename std::enable_if<(1), int>::type* = nullptr>;
template<2, 3, typename std::enable_if<(1), int>::type* = nullptr>;
template<2, 3, 4, 5, 6, typename std::enable_if<(1), int>::type* = nullptr>;
template< typename std::enable_if<(), int>::type* = nullptr>;
Может быть можно сделать сильно проще, но мне лень это разгребать
Исходная версия SZT, :
Вот решение на основе старого макроговнокода, который я когда-то нагугливал (не уверен что оптимальное)
#define SPLICE(a,b) SPLICE_1(a,b)
#define SPLICE_1(a,b) SPLICE_2(a,b)
#define SPLICE_2(a,b) a##b
#define PP_ARG_N( \
_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, \
_11, _12, _13, _14, _15, _16, _17, _18, _19, _20, \
_21, _22, _23, _24, _25, _26, _27, _28, _29, _30, \
_31, _32, _33, _34, _35, _36, _37, _38, _39, _40, \
_41, _42, _43, _44, _45, _46, _47, _48, _49, _50, \
_51, _52, _53, _54, _55, _56, _57, _58, _59, _60, \
_61, _62, _63, N, ...) N
/* Note 63 is removed */
#define PP_RSEQ_N() \
62, 61, 60, \
59, 58, 57, 56, 55, 54, 53, 52, 51, 50, \
49, 48, 47, 46, 45, 44, 43, 42, 41, 40, \
39, 38, 37, 36, 35, 34, 33, 32, 31, 30, \
29, 28, 27, 26, 25, 24, 23, 22, 21, 20, \
19, 18, 17, 16, 15, 14, 13, 12, 11, 10, \
9, 8, 7, 6, 5, 4, 3, 2, 1, 0
#define PP_NARG_(...) PP_ARG_N(__VA_ARGS__)
#define PP_NARG(...) PP_NARG_(_, ##__VA_ARGS__, PP_RSEQ_N())
#define INCR 20
#define FIELD_0(...) // NOTHING
#define FIELD_1(field, ...) \
field,
#define FIELD_2(field, ...) \
field, FIELD_1(__VA_ARGS__)
#define FIELD_3(field, ...) \
field, FIELD_2(__VA_ARGS__)
#define FIELD_4(field, ...) \
field, FIELD_3(__VA_ARGS__)
#define FIELD_5(field, ...) \
field, FIELD_4(__VA_ARGS__)
#define FIELD_5(field, ...) \
field, FIELD_4(__VA_ARGS__)
#define FIELD_6(field, ...) \
field, FIELD_5(__VA_ARGS__)
#define FIELD_7(field, ...) \
field, FIELD_6(__VA_ARGS__)
#define FIELD_8(field, ...) \
field, FIELD_7(__VA_ARGS__)
#define FIELD_9(field, ...) \
field, FIELD_8(__VA_ARGS__)
#define FIELD_10(field, ...) \
field, FIELD_9(__VA_ARGS__),
#define FIELD_11(field, ...) \
field, FIELD_10(__VA_ARGS__)
//..... дальше лень ...
#define FIELDS_(N, ...) \
SPLICE(FIELD_, N)(__VA_ARGS__)
#define FIELDS(...) \
FIELDS_(PP_NARG(__VA_ARGS__), __VA_ARGS__)
#define $enable(COND, ARGS...) \
template<FIELDS(ARGS) typename std::enable_if<(COND), int>::type* = nullptr>
$enable(1);
$enable(1, 2);
$enable(1, 2, 3);
$enable(1, 2, 3, 4, 5, 6);
$enable();
template< typename std::enable_if<(1), int>::type* = nullptr>;
template<2, typename std::enable_if<(1), int>::type* = nullptr>;
template<2, 3, typename std::enable_if<(1), int>::type* = nullptr>;
template<2, 3, 4, 5, 6, typename std::enable_if<(1), int>::type* = nullptr>;
template< typename std::enable_if<(), int>::type* = nullptr>;
Может быть можно сделать сильно проще, но мне лень это разгребать