Is there any trick to achieve the function of the pseudo-code below? THX.
template <typename... T1, typename... T2>
void fake_fold((T1 t1, T2 t2)...) {
(std::make_pair(t1, t2)), ...; // std::pair<std::string, T2>, T1 type is always sd::string
}
#define FAKE_MACRO(a, b, c) fake_fold(???)
void main()
{
int var1;
std::string var2;
double var3;
FAKE_MACRO(var1, var2, var3);
/* macro expansion then pass to fake_fold:
fake_fold("var1", var1, "var2", var2, "var3", var3);
*/
/* fold expression expansion:
std::make_pair("var1", var1), std::make_pair("var2", var2), std::make_pair("var3", var3),
*/
}
Shortly,
using FAKE_MACRO(var1, var2, var3); i want to get the expansion code
std::make_pair("var1", var1), std::make_pair("var2", var2), std::make_pair("var3", var3)
var0 ... varn
From foreach-macro-on-macros-arguments
#define PP_NARG(...) PP_NARG_(__VA_ARGS__,PP_RSEQ_N())
#define PP_NARG_(...) PP_ARG_N(__VA_ARGS__)
#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
#define PP_RSEQ_N() \
63,62,61,60, \
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
/* need extra level to force extra eval */
#define Paste(a,b) a ## b
#define XPASTE(a,b) Paste(a,b)
/* APPLYXn variadic X-Macro by M Joshua Ryan */
/* Free for all uses. Don't be a jerk. */
/* I got bored after typing 15 of these. */
/* You could keep going upto 64 (PPNARG's limit). */
#define APPLYX1(a) X(a)
#define APPLYX2(a,b) X(a), X(b)
#define APPLYX3(a,b,c) X(a), X(b), X(c)
#define APPLYX4(a,b,c,d) X(a), X(b), X(c), X(d)
#define APPLYX5(a,b,c,d,e) X(a), X(b), X(c), X(d), X(e)
#define APPLYX6(a,b,c,d,e,f) X(a), X(b), X(c), X(d), X(e), X(f)
#define APPLYX7(a,b,c,d,e,f,g) \
X(a), X(b), X(c), X(d), X(e), X(f), X(g)
#define APPLYX8(a,b,c,d,e,f,g,h) \
X(a), X(b), X(c), X(d), X(e), X(f), X(g), X(h)
#define APPLYX9(a,b,c,d,e,f,g,h,i) \
X(a), X(b), X(c), X(d), X(e), X(f), X(g), X(h), X(i)
#define APPLYX10(a,b,c,d,e,f,g,h,i,j) \
X(a), X(b), X(c), X(d), X(e), X(f), X(g), X(h), X(i), X(j)
#define APPLYX11(a,b,c,d,e,f,g,h,i,j,k) \
X(a), X(b), X(c), X(d), X(e), X(f), X(g), X(h), X(i), X(j), X(k)
#define APPLYX12(a,b,c,d,e,f,g,h,i,j,k,l) \
X(a), X(b), X(c), X(d), X(e), X(f), X(g), X(h), X(i), X(j), X(k), X(l)
#define APPLYX13(a,b,c,d,e,f,g,h,i,j,k,l,m) \
X(a), X(b), X(c), X(d), X(e), X(f), X(g), X(h), X(i), X(j), X(k), X(l), X(m)
#define APPLYX14(a,b,c,d,e,f,g,h,i,j,k,l,m,n) \
X(a), X(b), X(c), X(d), X(e), X(f), X(g), X(h), X(i), X(j), X(k), X(l), X(m), X(n)
#define APPLYX15(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o) \
X(a), X(b), X(c), X(d), X(e), X(f), X(g), X(h), X(i), X(j), X(k), X(l), X(m), X(n), X(o)
#define APPLYX_(M, ...) M(__VA_ARGS__)
#define APPLYXn(...) APPLYX_(XPASTE(APPLYX, PP_NARG(__VA_ARGS__)), __VA_ARGS__)
#define X(a) std::make_pair(#a, a)
#define FAKE_MACRO(...) fake_fold(APPLYXn(__VA_ARGS__))
int main()
{
int var1 = 42;
std::string var2 = "toto";
double var3 = 5.1;
FAKE_MACRO(var1, var2, var3);
}