compile-time generation of compile-time checked KVC key paths

gistfile1.txt

#import <Foundation/Foundation.h>


#define KVCKeyPath_1(a) @"" a
#define KVCKeyPath_2(a, ...) a @"." KVCKeyPath_1(__VA_ARGS__)
#define KVCKeyPath_3(a, ...) a @"." KVCKeyPath_2(__VA_ARGS__)
#define KVCKeyPath_4(a, ...) a @"." KVCKeyPath_3(__VA_ARGS__)
#define KVCKeyPath_5(a, ...) a @"." KVCKeyPath_4(__VA_ARGS__)
#define KVCKeyPath_6(a, ...) a @"." KVCKeyPath_5(__VA_ARGS__)
#define KVCKeyPath_7(a, ...) a @"." KVCKeyPath_6(__VA_ARGS__)
#define KVCKeyPath_8(a, ...) a @"." KVCKeyPath_7(__VA_ARGS__)
#define KVCKeyPath_9(a, ...) a @"." KVCKeyPath_8(__VA_ARGS__)
#define KVCKeyPath_10(a, ...) a @"." KVCKeyPath_9(__VA_ARGS__)
#define KVCKeyPath_11(a, ...) a @"." KVCKeyPath_10(__VA_ARGS__)
#define KVCKeyPath_12(a, ...) a @"." KVCKeyPath_11(__VA_ARGS__)
#define KVCKeyPath_13(a, ...) a @"." KVCKeyPath_12(__VA_ARGS__)
#define KVCKeyPath_14(a, ...) a @"." KVCKeyPath_13(__VA_ARGS__)
#define KVCKeyPath_15(a, ...) a @"." KVCKeyPath_14(__VA_ARGS__)
#define KVCKeyPath_16(a, ...) a @"." KVCKeyPath_15(__VA_ARGS__)

#define KVC_NUM_ARGS(...) KVC_NUM_ARGS_IMPL(__VA_ARGS__,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1)
#define KVC_NUM_ARGS_IMPL(_1,_2,_3,_4,_5,_6,_7,_8,_9,_10,_11,_12,_13,_14,_15,_16,N,...) N

#define KVCKeyPath_Helper_2(N, ...) (KVCKeyPath_ ## N(__VA_ARGS__))
#define KVCKeyPath_Helper_1(N, ...) KVCKeyPath_Helper_2(N, __VA_ARGS__)
#define KVCKeyPath(...) KVCKeyPath_Helper_1(KVC_NUM_ARGS(__VA_ARGS__), __VA_ARGS__)

#define FooKey @"foo"
#define BarKey @"bar"
#define BazKey @"baz"

int main(int argc, const char * argv[])
{
    NSLog(KVCKeyPath(FooKey, BarKey, BazKey));
    return 0;
}