make_from_tuple.hpp

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//
// Created by yonggyulee on 2023/10/27.
//
 
#ifndef VCCC_TUPLE_MAKE_FROM_TUPLE_HPP
#define VCCC_TUPLE_MAKE_FROM_TUPLE_HPP
 
#include <cstddef>
#include <type_traits>
#include <utility>
 
namespace vccc {
 
 
namespace internal {
 
template<typename T, typename Tuple, std::size_t... I>
constexpr T make_from_tuple_impl(Tuple&& t, std::index_sequence<I...>) {
  return T(std::get<I>(std::forward<Tuple>(t))...);
}
 
template<typename T, typename Tuple, typename I>
struct is_constructible_from_tuple_impl;
 
template<typename T, typename Tuple, std::size_t... I>
struct is_constructible_from_tuple_impl<T, Tuple, std::index_sequence<I...>>
    : std::is_constructible<T, decltype(std::get<I>(std::declval<Tuple>()))...> {};
 
template<typename T, typename Tuple>
struct is_constructible_from_tuple
    : is_constructible_from_tuple_impl<T,
                                       Tuple,
                                       std::make_index_sequence<
                                           std::tuple_size<std::remove_reference_t<Tuple>>::value>> {};
 
} // namespace internal
 
// TODO(Tony): Constraint on Tuple? (C++23)
 
template<typename T, typename Tuple, std::enable_if_t<internal::is_constructible_from_tuple<T, Tuple>::value, int> = 0>
constexpr T make_from_tuple(Tuple&& t) {
  return internal::make_from_tuple_impl<T>(
      std::forward<Tuple>(t),
      std::make_index_sequence<std::tuple_size<std::remove_reference_t<Tuple>>::value>{});
}
 
 
} // namespace vccc
 
#endif // VCCC_TUPLE_MAKE_FROM_TUPLE_HPP