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entt_traits: split basic impl, simplify def

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This commit is contained in:
Michele Caini
2022-11-28 12:48:16 +01:00
parent 782d86b6e7
commit 92319f0111
1 changed files with 40 additions and 20 deletions
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60
src/entt/entity/entity.hpp
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@@ -16,35 +16,47 @@ namespace entt {
namespace internal {
// waiting for C++20 (and std::popcount)
template<typename Type>
static constexpr int popcount(Type value) noexcept {
return value ? (int(value & 1) + popcount(value >> 1)) : 0;
}
template<typename, typename = void>
struct entt_traits;
template<typename Type>
struct entt_traits<Type, std::enable_if_t<std::is_enum_v<Type>>>
: entt_traits<std::underlying_type_t<Type>> {};
: entt_traits<std::underlying_type_t<Type>> {
using type = Type;
};
template<typename Type>
struct entt_traits<Type, std::enable_if_t<std::is_class_v<Type>>>
: entt_traits<typename Type::entity_type> {};
: entt_traits<typename Type::entity_type> {
using type = Type;
};
template<>
struct entt_traits<std::uint32_t> {
using type = std::uint32_t;
using entity_type = std::uint32_t;
using version_type = std::uint16_t;
static constexpr entity_type entity_mask = 0xFFFFF;
static constexpr entity_type version_mask = 0xFFF;
static constexpr std::size_t entity_shift = 20u;
};
template<>
struct entt_traits<std::uint64_t> {
using type = std::uint64_t;
using entity_type = std::uint64_t;
using version_type = std::uint32_t;
static constexpr entity_type entity_mask = 0xFFFFFFFF;
static constexpr entity_type version_mask = 0xFFFFFFFF;
static constexpr std::size_t entity_shift = 32u;
};
} // namespace internal
@@ -55,22 +67,20 @@ struct entt_traits<std::uint64_t> {
*/
/**
* @brief Entity traits.
* @tparam Type Type of identifier.
* @brief Common basic entity traits implementation.
* @tparam Traits Actual entity traits to use.
*/
template<typename Type>
class entt_traits: internal::entt_traits<Type> {
using base_type = internal::entt_traits<Type>;
template<typename Traits>
class basic_entt_traits {
static constexpr auto entity_shift = internal::popcount(Traits::entity_mask);
public:
/*! @brief Entity type. */
using type = Type;
using type = typename Traits::type;
/*! @brief Underlying entity type. */
using entity_type = typename base_type::entity_type;
using entity_type = typename Traits::entity_type;
/*! @brief Underlying version type. */
using version_type = typename base_type::version_type;
/*! @brief Page size, default is `ENTT_SPARSE_PAGE`. */
static constexpr std::size_t page_size = ENTT_SPARSE_PAGE;
using version_type = typename Traits::version_type;
/**
* @brief Converts an entity to its underlying type.
@@ -87,7 +97,7 @@ public:
* @return The integral representation of the entity part.
*/
[[nodiscard]] static constexpr entity_type to_entity(const type value) noexcept {
return (to_integral(value) & base_type::entity_mask);
return (to_integral(value) & Traits::entity_mask);
}
/**
@@ -96,7 +106,7 @@ public:
* @return The integral representation of the version part.
*/
[[nodiscard]] static constexpr version_type to_version(const type value) noexcept {
return (to_integral(value) >> base_type::entity_shift);
return (to_integral(value) >> entity_shift);
}
/**
@@ -109,8 +119,8 @@ public:
* @param version The version part of the identifier.
* @return A properly constructed identifier.
*/
[[nodiscard]] static constexpr type construct(const entity_type entity = base_type::entity_mask, const version_type version = base_type::version_mask) noexcept {
return type{(entity & base_type::entity_mask) | (static_cast<entity_type>(version) << base_type::entity_shift)};
[[nodiscard]] static constexpr type construct(const entity_type entity = Traits::entity_mask, const version_type version = Traits::version_mask) noexcept {
return type{(entity & Traits::entity_mask) | (static_cast<entity_type>(version) << entity_shift)};
}
/**
@@ -124,11 +134,21 @@ public:
* @return A properly constructed identifier.
*/
[[nodiscard]] static constexpr type combine(const entity_type lhs, const entity_type rhs) noexcept {
constexpr auto mask = (base_type::version_mask << base_type::entity_shift);
return type{(lhs & base_type::entity_mask) | (rhs & mask)};
constexpr auto mask = (Traits::version_mask << entity_shift);
return type{(lhs & Traits::entity_mask) | (rhs & mask)};
}
};
/**
* @brief Entity traits.
* @tparam Type Type of identifier.
*/
template<typename Type>
struct entt_traits: basic_entt_traits<internal::entt_traits<Type>> {
/*! @brief Page size, default is `ENTT_SPARSE_PAGE`. */
static constexpr std::size_t page_size = ENTT_SPARSE_PAGE;
};
/**
* @copydoc entt_traits<Entity>::to_integral
* @tparam Entity The value type.