Program Listing for File tuple_traits.hpp

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//==--- ripple/core/container/tuple_traits.hpp ------------- -*- C++ -*- ---==//
//
//                                Ripple
//
//                      Copyright (c) 2019, 2020 Rob Clucas
//
//  This file is distributed under the MIT License. See LICENSE for details.
//
//==------------------------------------------------------------------------==//
//

#ifndef RIPPLE_CONTAINER_TUPLE_TRAITS_HPP
#define RIPPLE_CONTAINER_TUPLE_TRAITS_HPP

#include "detail/basic_tuple_.hpp"
#include <ripple/utility/type_traits.hpp>

namespace ripple {

/*==--- [forward declarations] ---------------------------------------------==*/

template <typename... Types>
class Tuple;

/*==--- [traits] -----------------------------------------------------------==*/

namespace detail {

template <typename T>
struct TupleTraits {
  static constexpr size_t size = 0;
};

template <typename... Ts>
struct TupleTraits<Tuple<Ts...>> {
  static constexpr size_t size = sizeof...(Ts);
};

template <typename T>
struct IsTuple {
  static constexpr bool value = false;
};

template <typename... Ts>
struct IsTuple<Tuple<Ts...>> {
  static constexpr bool value = true;
};

template <size_t I, typename T>
struct TupleElement {
  using DataType = decltype(std::declval<T>().data());

  using Type =
    decltype(type_extractor<I>(static_cast<std::remove_reference_t<DataType>&&>(
      std::declval<T>().data())));
};

template <size_t I>
struct TupleElement<I, Tuple<>> {
  using Type = void;
};

} // namespace detail

template <typename T>
using tuple_traits_t = detail::TupleTraits<std::decay_t<T>>;

template <size_t I, typename T>
using tuple_element_t = typename detail::TupleElement<I, T>::Type;

template <typename T>
static constexpr bool is_tuple_v = detail::IsTuple<std::decay_t<T>>::value;

template <typename T>
static constexpr size_t tuple_size_v = tuple_traits_t<T>::size;

/*==--- [enables] ----------------------------------------------------------==*/

template <typename... Ts>
using tuple_enable_t =
  std::enable_if_t<is_tuple_v<nth_element_t<0, Ts...>>, int>;

template <typename... Ts>
using non_tuple_enable_t =
  std::enable_if_t<!is_tuple_v<nth_element_t<0, Ts...>>, int>;

} // namespace ripple

#endif // RIPPLE_CONTAINER_TUPLE_HPP