C++ Tricks

array_to_tuple.cpp

// base case
template <class... Types, size_t n, size_t... indices>
std::tuple<Types...> toAnyTuple(
    std::array<std::any, n> const& arr,
    std::index_sequence<indices...>) {
  return std::make_tuple(std::any_cast<Types&>(arr[indices])...);
}
// general case
template <
    class... Types,
    size_t n,
    class = std::enable_if_t<(n == sizeof...(Types))>>
std::tuple<Types...> toAnyTuple(std::array<std::any, n> const& arr) {
  return toAnyTuple<Types...>(arr, std::make_index_sequence<n>{});
}

tips.cpp

std::tuple_cat;

std::any;

std::apply;
// Call funciton with parameters in Tuple
// Use the lambda wrapper to avoid calling non-static function directly.

// get type in C++
// https://stackoverflow.com/questions/28509273/get-types-of-c-function-parameters

tuple_to_vector.cpp

template <class Tuple,
   class T = std::decay_t<std::tuple_element_t<0, std::decay_t<Tuple>>>>
std::vector<T> to_vector(Tuple&& tuple)
{
     return std::apply([](auto&&... elems) {
        std::vector<T> result;
        result.reserve(sizeof...(elems));
        (result.push_back(std::forward<decltype(elems)>(elems)), ...);
        return result;
    }, std::forward<Tuple>(tuple));
}