LiteLoaderBDS-1.16.40/LiteLoader/Header/third-party/entt/core/ident.hpp
2022-09-21 19:47:03 +08:00

65 lines
1.6 KiB
C++

#ifndef ENTT_CORE_IDENT_HPP
#define ENTT_CORE_IDENT_HPP
#include <cstddef>
#include <utility>
#include <type_traits>
#include "../config/config.h"
#include "fwd.hpp"
#include "type_traits.hpp"
namespace entt {
/**
* @brief Types identifiers.
*
* Variable template used to generate identifiers at compile-time for the given
* types. Use the `get` member function to know what's the identifier associated
* to the specific type.
*
* @note
* Identifiers are constant expression and can be used in any context where such
* an expression is required. As an example:
* @code{.cpp}
* using id = entt::identifier<a_type, another_type>;
*
* switch(a_type_identifier) {
* case id::type<a_type>:
* // ...
* break;
* case id::type<another_type>:
* // ...
* break;
* default:
* // ...
* }
* @endcode
*
* @tparam Types List of types for which to generate identifiers.
*/
template<typename... Types>
class identifier {
template<typename Type, std::size_t... Index>
[[nodiscard]] static constexpr id_type get(std::index_sequence<Index...>) {
static_assert(std::disjunction_v<std::is_same<Type, Types>...>, "Invalid type");
return (0 + ... + (std::is_same_v<Type, type_list_element_t<Index, type_list<std::decay_t<Types>...>>> ? id_type{Index} : id_type{}));
}
public:
/*! @brief Unsigned integer type. */
using identifier_type = id_type;
/*! @brief Statically generated unique identifier for the given type. */
template<typename Type>
static constexpr identifier_type type = get<std::decay_t<Type>>(std::index_sequence_for<Types...>{});
};
}
#endif