C++11 typelists

typelist.cpp

struct NullType {};

template <typename T, typename U>
struct TypeList {
    using Head = T;
    using Tail = U;
};

template <typename...> struct MakeTypeList;

template <>
struct MakeTypeList<> {
    using Result = NullType;
};

template <typename Head, typename... Types>
struct MakeTypeList<Head, Types...> {
    using Result = TypeList<Head, typename MakeTypeList<Types...>::Result>;
};

/**
*/
template <typename> struct Length;

template <>
struct Length<NullType> {
    enum { value = 0 };
};

template <typename Head, typename Tail>
struct Length<TypeList<Head, Tail>> {
    enum { value = Length<Tail>::value + 1 };
};

/**
*/
template <typename, typename> struct IndexOf;

template <typename T>
struct IndexOf<NullType, T> {
    enum { value = -1 };
};

template <typename T, typename Tail>
struct IndexOf<TypeList<T, Tail>, T> {
    enum { value = 0 };
};

template <typename Head, typename Tail, typename T>
struct IndexOf<TypeList<Head, Tail>, T> {
    using Result = IndexOf<Tail, T>;
    enum { value = Result::value == -1 ? -1 : Result::value + 1 };
};

#include <iostream>

int main() {
    using IntTypes = typename MakeTypeList<char, bool, void>::Result;

    std::cout << "Length<> : " << Length<IntTypes>::value << '\n';
    std::cout << "IndexOf<char> : " << IndexOf<IntTypes, char>::value << '\n';
    std::cout << "IndexOf<bool> : " << IndexOf<IntTypes, bool>::value << '\n';
    std::cout << "IndexOf<int> : " << IndexOf<IntTypes, int>::value << '\n';
    std::cout << "IndexOf<void> : " << IndexOf<IntTypes, void>::value << '\n';
}