Check if one set of types is a subset of the other

Question

How can one check if one parameter pack (interpreted as a set) is a subset of another one?

So far I only have the frame (using std::tuple), but no functionality.

Answer 1

is_subset_of version of an answer from your previous question:

#include 
#include 

template 
struct tag { };

template 
struct is_subset_of_helper: tag... { };

template 
struct is_subset_of: std::false_type { };

template 
struct bool_pack { };

template 
using my_and = std::is_same, bool_pack>;

template 
struct is_subset_of, std::tuple, typename std::enable_if< my_and< std::is_base_of, is_subset_of_helper>::value...  >::value  >::type  >:
   std::true_type { };

int main() {    
    using t1 = std::tuple;
    using t2 = std::tuple;
    using t3 = std::tuple;

    static_assert(is_subset_of::value, "err");
    static_assert(is_subset_of::value, "err");
    static_assert(is_subset_of::value, "err");
    static_assert(is_subset_of::value, "err");
    static_assert(!is_subset_of::value, "err");
}

[live demo]