#ifndef ENTT_ENTITY_COMPONENT_HPP #define ENTT_ENTITY_COMPONENT_HPP #include <cstddef> #include <type_traits> #include "../config/config.h" namespace entt { /** * @cond TURN_OFF_DOXYGEN * Internal details not to be documented. */ namespace internal { template<typename Type, typename = void> struct in_place_delete: std::bool_constant<!(std::is_move_constructible_v<Type> && std::is_move_assignable_v<Type>)> {}; template<typename Type> struct in_place_delete<Type, std::enable_if_t<Type::in_place_delete>> : std::true_type {}; template<typename Type, typename = void> struct page_size: std::integral_constant<std::size_t, !std::is_empty_v<ENTT_ETO_TYPE(Type)> * ENTT_PACKED_PAGE> {}; template<typename Type> struct page_size<Type, std::enable_if_t<std::is_convertible_v<decltype(Type::page_size), std::size_t>>> : std::integral_constant<std::size_t, Type::page_size> {}; } // namespace internal /** * Internal details not to be documented. * @endcond */ /** * @brief Common way to access various properties of components. * @tparam Type Type of component. */ template<typename Type, typename = void> struct component_traits { static_assert(std::is_same_v<std::decay_t<Type>, Type>, "Unsupported type"); /*! @brief Component type. */ using type = Type; /*! @brief Pointer stability, default is `false`. */ static constexpr bool in_place_delete = internal::in_place_delete<Type>::value; /*! @brief Page size, default is `ENTT_PACKED_PAGE` for non-empty types. */ static constexpr std::size_t page_size = internal::page_size<Type>::value; }; /** * @brief Helper variable template. * @tparam Type Type of component. */ template<class Type> inline constexpr bool ignore_as_empty_v = (std::is_void_v<Type> || component_traits<Type>::page_size == 0u); } // namespace entt #endif