Variadic Template: Make Index Sequence, C++ (clang)

Variadic Template: Make Index Sequence

#include <iostream>
#include <type_traits>

using SizeT = int;

template <SizeT...>
struct index_sequence {};

///////////////////////////////
template <SizeT Step>
struct Helper
{
    template <SizeT Count, SizeT Limit, SizeT ... Z>
    struct index_sequence_helper
    {
        using type = typename index_sequence_helper<Count-1, Limit-Step, Limit, Z...>::type;
    };

template <SizeT A, SizeT ... Z>
    struct index_sequence_helper<1, A, Z...>
    {
        using type = index_sequence<A, Z...>;
    };
};

///////////////////////////////
template <SizeT From, SizeT To>
constexpr bool FromMoreThanTo() { return (From > To); }

template <SizeT From, SizeT To>
constexpr auto make(std::enable_if_t<FromMoreThanTo<From, To>(), bool> = true)
{
    return typename Helper<-1>::template index_sequence_helper<(From-To)+1, To>::type();
}

template <SizeT From, SizeT To>
constexpr auto make(std::enable_if_t<!FromMoreThanTo<From, To>(), bool> = true)
{
    return typename Helper<1>::template index_sequence_helper<(To-From)+1, To>::type();
}
///////////////////////////////

template <SizeT ... S>
void print(index_sequence<S...>)
{
    SizeT val[] = {S...} ;

std::cout << "[" << sizeof...(S) << "]\t";
    for (auto v : val)
        std::cout << v << ' ';

std::cout << "\n";
}

int main()
{
    print(make<6, 2>());
    print(make<2, 6>());

print(make<-6, 2>());
    print(make<-2, 6>());

return 0;
}


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