🛠️🐜 Antkeeper superbuild with dependencies included
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339 lines
11 KiB
339 lines
11 KiB
#ifndef ENTT_ENTITY_ENTITY_HPP
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#define ENTT_ENTITY_ENTITY_HPP
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#include <cstddef>
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#include <cstdint>
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#include <type_traits>
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#include "../config/config.h"
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#include "fwd.hpp"
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namespace entt {
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/**
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* @cond TURN_OFF_DOXYGEN
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* Internal details not to be documented.
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*/
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namespace internal {
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template<typename, typename = void>
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struct entt_traits;
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template<typename Type>
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struct entt_traits<Type, std::enable_if_t<std::is_enum_v<Type>>>
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: entt_traits<std::underlying_type_t<Type>> {};
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template<typename Type>
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struct entt_traits<Type, std::enable_if_t<std::is_class_v<Type>>>
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: entt_traits<typename Type::entity_type> {};
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template<>
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struct entt_traits<std::uint32_t> {
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using entity_type = std::uint32_t;
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using version_type = std::uint16_t;
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static constexpr entity_type entity_mask = 0xFFFFF;
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static constexpr entity_type version_mask = 0xFFF;
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static constexpr std::size_t entity_shift = 20u;
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};
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template<>
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struct entt_traits<std::uint64_t> {
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using entity_type = std::uint64_t;
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using version_type = std::uint32_t;
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static constexpr entity_type entity_mask = 0xFFFFFFFF;
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static constexpr entity_type version_mask = 0xFFFFFFFF;
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static constexpr std::size_t entity_shift = 32u;
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};
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} // namespace internal
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/**
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* Internal details not to be documented.
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* @endcond
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*/
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/**
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* @brief Entity traits.
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* @tparam Type Type of identifier.
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*/
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template<typename Type>
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class entt_traits: internal::entt_traits<Type> {
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using base_type = internal::entt_traits<Type>;
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public:
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/*! @brief Value type. */
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using value_type = Type;
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/*! @brief Underlying entity type. */
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using entity_type = typename base_type::entity_type;
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/*! @brief Underlying version type. */
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using version_type = typename base_type::version_type;
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/*! @brief Reserved identifier. */
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static constexpr entity_type reserved = base_type::entity_mask | (base_type::version_mask << base_type::entity_shift);
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/*! @brief Page size, default is `ENTT_SPARSE_PAGE`. */
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static constexpr auto page_size = ENTT_SPARSE_PAGE;
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/**
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* @brief Converts an entity to its underlying type.
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* @param value The value to convert.
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* @return The integral representation of the given value.
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*/
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[[nodiscard]] static constexpr entity_type to_integral(const value_type value) ENTT_NOEXCEPT {
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return static_cast<entity_type>(value);
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}
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/**
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* @brief Returns the entity part once converted to the underlying type.
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* @param value The value to convert.
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* @return The integral representation of the entity part.
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*/
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[[nodiscard]] static constexpr entity_type to_entity(const value_type value) ENTT_NOEXCEPT {
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return (to_integral(value) & base_type::entity_mask);
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}
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/**
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* @brief Returns the version part once converted to the underlying type.
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* @param value The value to convert.
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* @return The integral representation of the version part.
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*/
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[[nodiscard]] static constexpr version_type to_version(const value_type value) ENTT_NOEXCEPT {
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return (to_integral(value) >> base_type::entity_shift);
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}
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/**
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* @brief Constructs an identifier from its parts.
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*
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* If the version part is not provided, a tombstone is returned.<br/>
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* If the entity part is not provided, a null identifier is returned.
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*
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* @param entity The entity part of the identifier.
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* @param version The version part of the identifier.
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* @return A properly constructed identifier.
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*/
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[[nodiscard]] static constexpr value_type construct(const entity_type entity, const version_type version) ENTT_NOEXCEPT {
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return value_type{(entity & base_type::entity_mask) | (static_cast<entity_type>(version) << base_type::entity_shift)};
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}
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/**
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* @brief Combines two identifiers in a single one.
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*
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* The returned identifier is a copy of the first element except for its
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* version, which is taken from the second element.
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*
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* @param lhs The identifier from which to take the entity part.
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* @param rhs The identifier from which to take the version part.
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* @return A properly constructed identifier.
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*/
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[[nodiscard]] static constexpr value_type combine(const entity_type lhs, const entity_type rhs) ENTT_NOEXCEPT {
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constexpr auto mask = (base_type::version_mask << base_type::entity_shift);
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return value_type{(lhs & base_type::entity_mask) | (rhs & mask)};
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}
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};
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/**
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* @copydoc entt_traits<Entity>::to_integral
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* @tparam Entity The value type.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr typename entt_traits<Entity>::entity_type to_integral(const Entity value) ENTT_NOEXCEPT {
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return entt_traits<Entity>::to_integral(value);
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}
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/**
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* @copydoc entt_traits<Entity>::to_entity
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* @tparam Entity The value type.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr typename entt_traits<Entity>::entity_type to_entity(const Entity value) ENTT_NOEXCEPT {
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return entt_traits<Entity>::to_entity(value);
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}
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/**
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* @copydoc entt_traits<Entity>::to_version
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* @tparam Entity The value type.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr typename entt_traits<Entity>::version_type to_version(const Entity value) ENTT_NOEXCEPT {
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return entt_traits<Entity>::to_version(value);
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}
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/*! @brief Null object for all identifiers. */
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struct null_t {
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/**
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* @brief Converts the null object to identifiers of any type.
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* @tparam Entity Type of identifier.
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* @return The null representation for the given type.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr operator Entity() const ENTT_NOEXCEPT {
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using entity_traits = entt_traits<Entity>;
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return entity_traits::combine(entity_traits::reserved, entity_traits::reserved);
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}
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/**
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* @brief Compares two null objects.
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* @param other A null object.
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* @return True in all cases.
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*/
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[[nodiscard]] constexpr bool operator==([[maybe_unused]] const null_t other) const ENTT_NOEXCEPT {
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return true;
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}
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/**
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* @brief Compares two null objects.
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* @param other A null object.
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* @return False in all cases.
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*/
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[[nodiscard]] constexpr bool operator!=([[maybe_unused]] const null_t other) const ENTT_NOEXCEPT {
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return false;
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}
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/**
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* @brief Compares a null object and an identifier of any type.
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* @tparam Entity Type of identifier.
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* @param entity Identifier with which to compare.
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* @return False if the two elements differ, true otherwise.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr bool operator==(const Entity entity) const ENTT_NOEXCEPT {
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using entity_traits = entt_traits<Entity>;
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return entity_traits::to_entity(entity) == entity_traits::to_entity(*this);
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}
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/**
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* @brief Compares a null object and an identifier of any type.
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* @tparam Entity Type of identifier.
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* @param entity Identifier with which to compare.
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* @return True if the two elements differ, false otherwise.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr bool operator!=(const Entity entity) const ENTT_NOEXCEPT {
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return !(entity == *this);
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}
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};
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/**
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* @brief Compares a null object and an identifier of any type.
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* @tparam Entity Type of identifier.
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* @param entity Identifier with which to compare.
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* @param other A null object yet to be converted.
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* @return False if the two elements differ, true otherwise.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr bool operator==(const Entity entity, const null_t other) ENTT_NOEXCEPT {
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return other.operator==(entity);
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}
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/**
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* @brief Compares a null object and an identifier of any type.
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* @tparam Entity Type of identifier.
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* @param entity Identifier with which to compare.
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* @param other A null object yet to be converted.
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* @return True if the two elements differ, false otherwise.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr bool operator!=(const Entity entity, const null_t other) ENTT_NOEXCEPT {
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return !(other == entity);
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}
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/*! @brief Tombstone object for all identifiers. */
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struct tombstone_t {
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/**
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* @brief Converts the tombstone object to identifiers of any type.
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* @tparam Entity Type of identifier.
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* @return The tombstone representation for the given type.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr operator Entity() const ENTT_NOEXCEPT {
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using entity_traits = entt_traits<Entity>;
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return entity_traits::combine(entity_traits::reserved, entity_traits::reserved);
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}
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/**
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* @brief Compares two tombstone objects.
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* @param other A tombstone object.
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* @return True in all cases.
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*/
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[[nodiscard]] constexpr bool operator==([[maybe_unused]] const tombstone_t other) const ENTT_NOEXCEPT {
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return true;
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}
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/**
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* @brief Compares two tombstone objects.
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* @param other A tombstone object.
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* @return False in all cases.
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*/
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[[nodiscard]] constexpr bool operator!=([[maybe_unused]] const tombstone_t other) const ENTT_NOEXCEPT {
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return false;
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}
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/**
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* @brief Compares a tombstone object and an identifier of any type.
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* @tparam Entity Type of identifier.
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* @param entity Identifier with which to compare.
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* @return False if the two elements differ, true otherwise.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr bool operator==(const Entity entity) const ENTT_NOEXCEPT {
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using entity_traits = entt_traits<Entity>;
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return entity_traits::to_version(entity) == entity_traits::to_version(*this);
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}
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/**
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* @brief Compares a tombstone object and an identifier of any type.
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* @tparam Entity Type of identifier.
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* @param entity Identifier with which to compare.
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* @return True if the two elements differ, false otherwise.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr bool operator!=(const Entity entity) const ENTT_NOEXCEPT {
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return !(entity == *this);
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}
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};
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/**
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* @brief Compares a tombstone object and an identifier of any type.
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* @tparam Entity Type of identifier.
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* @param entity Identifier with which to compare.
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* @param other A tombstone object yet to be converted.
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* @return False if the two elements differ, true otherwise.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr bool operator==(const Entity entity, const tombstone_t other) ENTT_NOEXCEPT {
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return other.operator==(entity);
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}
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/**
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* @brief Compares a tombstone object and an identifier of any type.
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* @tparam Entity Type of identifier.
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* @param entity Identifier with which to compare.
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* @param other A tombstone object yet to be converted.
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* @return True if the two elements differ, false otherwise.
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*/
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template<typename Entity>
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[[nodiscard]] constexpr bool operator!=(const Entity entity, const tombstone_t other) ENTT_NOEXCEPT {
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return !(other == entity);
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}
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/**
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* @brief Compile-time constant for null entities.
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*
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* There exist implicit conversions from this variable to identifiers of any
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* allowed type. Similarly, there exist comparison operators between the null
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* entity and any other identifier.
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*/
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inline constexpr null_t null{};
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/**
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* @brief Compile-time constant for tombstone entities.
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*
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* There exist implicit conversions from this variable to identifiers of any
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* allowed type. Similarly, there exist comparison operators between the
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* tombstone entity and any other identifier.
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*/
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inline constexpr tombstone_t tombstone{};
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} // namespace entt
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#endif
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