c++ - BOOST_PP_TUPLE_SIZE() and empty tuple '()' -

i have sequence of tuples: '(int,double)(char)()'

i need detect tuple empty or not. boost_pp_tuple_size() returns 1 if tuple empty.

tell me please, how can check tuple not contain elements?

edit1 example:

#include <boost/preprocessor/tuple/size.hpp>  #define tuple0 () #define tuple1 (1) #define tuple2 (1,2)  0:boost_pp_tuple_size(tuple0) // -> 1 1:boost_pp_tuple_size(tuple1) // -> 1 2:boost_pp_tuple_size(tuple2) // -> 2 

solution based on the: http://gustedt.wordpress.com/2010/06/08/detect-empty-macro-arguments/

#include <boost/preprocessor.hpp>  /***************************************************************************/  #define _arg16(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, ...) _15 #define has_comma(...) _arg16(__va_args__, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0) #define _trigger_parenthesis_(...) ,  #define isempty(...) \     _isempty( \         /* test if there 1 argument, empty 1 */ \         has_comma(__va_args__), \         /* test if _trigger_parenthesis_ argument adds comma */ \         has_comma(_trigger_parenthesis_ __va_args__),                 \         /* test if argument parenthesis adds comma */ \         has_comma(__va_args__ (/*empty*/)), \         /* test if placing between _trigger_parenthesis_ , parenthesis adds comma */ \         has_comma(_trigger_parenthesis_ __va_args__ (/*empty*/)) \     )  #define paste5(_0, _1, _2, _3, _4) _0 ## _1 ## _2 ## _3 ## _4 #define _isempty(_0, _1, _2, _3) has_comma(paste5(_is_empty_case_, _0, _1, _2, _3)) #define _is_empty_case_0001 ,  #define tuple_to_args(...)  __va_args__ #define print_tuple( tuple_name ) tuple_to_args tuple_name  /***************************************************************************/  #define tuple0 () #define tuple1 (1) #define tuple2 (1,2) #define tuple3 (1,2,3) #define tuple4 (1,2,3,4) #define tuple5 (1,2,3,4,5) #define tuple6 (1,2,3,4,5,6) #define tuple7 (1,2,3,4,5,6,7) #define tuple8 (1,2,3,4,5,6,7,8) #define tuple9 (1,2,3,4,5,6,7,8,9)  /***************************************************************************/  int main() {     0:isempty(print_tuple(tuple0))     1:isempty(print_tuple(tuple1))     2:isempty(print_tuple(tuple2))     3:isempty(print_tuple(tuple3))     4:isempty(print_tuple(tuple4))     5:isempty(print_tuple(tuple5))     6:isempty(print_tuple(tuple6))     7:isempty(print_tuple(tuple7))     8:isempty(print_tuple(tuple8))     9:isempty(print_tuple(tuple9)) }  /***************************************************************************/ 

result:

int main() {  0:1  1:0  2:0  3:0  4:0  5:0  6:0  7:0  8:0  9:0 }