cpp-stateful-serializer/include/serializer/traits.h

//
//  traits.h
//  serializer
//
//  Created by Sam Jaffe on 3/15/23.
//

#pragma once

namespace serializer::detail {
template <typename> struct always_false : std::false_type {};

// Don't capture Aggregate objects lol...
template <typename, typename = void> struct is_tuple : std::false_type {};
template <typename K, typename V>
struct is_tuple<std::pair<K, V>> : std::true_type {};
template <typename T, size_t N>
struct is_tuple<std::array<T, N>> : std::true_type {};
template <typename... Ts>
struct is_tuple<std::tuple<Ts...>> : std::true_type {};

template <typename, typename = void> struct is_wrapper : std::false_type {};
template <typename T>
struct is_wrapper<T, std::void_t<typename T::value_type>> : std::true_type {};

template <typename, typename = void> struct is_container : std::false_type {};
template <typename T>
struct is_container<T, std::void_t<decltype(std::begin(std::declval<T>()))>>
    : is_wrapper<T> {};

template <typename, typename = void>
struct is_associative_container : std::false_type {};
template <typename T>
struct is_associative_container<T, std::void_t<typename T::mapped_type>>
    : std::true_type {};

template <typename, typename = void>
struct has_serial_type : std::false_type {};
template <typename T>
struct has_serial_type<T, std::void_t<typename T::serial_type>>
    : std::true_type {};

template <typename, typename = void>
struct is_dereferencable : std::false_type {};
template <typename T>
struct is_dereferencable<T, std::enable_if_t<!std::is_void_v<decltype(*T())>>>
    : std::true_type {};

template <typename T> constexpr bool is_tuple_v = is_tuple<T>{};
template <typename T> constexpr bool is_wrapper_v = is_wrapper<T>{};
template <typename T> constexpr bool is_container_v = is_container<T>{};
template <typename T>
constexpr bool is_associative_container_v =
    is_container_v<T> && is_associative_container<T>{};

template <typename T> constexpr bool has_serial_type_v = has_serial_type<T>{};
template <typename T>
constexpr bool is_dereferencable_v = is_dereferencable<T>{};
}