Class entt_traits

Synopsis

#include <src/entt/entity/entity.hpp>

template<typename Type>
class entt_traits: internal::entt_traits<Type>

Description

Entity traits.

Template Parameters

Type - Type of identifier.

Inheritance

Ancestors: internal::entt_traits< Type >

Methods

combineCombines two identifiers in a single one.
constructConstructs an identifier from its parts.
to_entityReturns the entity part once converted to the underlying type.
to_integralConverts an entity to its underlying type.
to_versionReturns the version part once converted to the underlying type.

Source

Lines 61-132 in src/entt/entity/entity.hpp.

template<typename Type>
class entt_traits: internal::entt_traits<Type> {
    using base_type = internal::entt_traits<Type>;

public:
    /*! @brief Value type. */
    using value_type = Type;
    /*! @brief Underlying entity type. */
    using entity_type = typename base_type::entity_type;
    /*! @brief Underlying version type. */
    using version_type = typename base_type::version_type;
    /*! @brief Reserved identifier. */
    static constexpr entity_type reserved = base_type::entity_mask | (base_type::version_mask << base_type::entity_shift);
    /*! @brief Page size, default is `ENTT_SPARSE_PAGE`. */
    static constexpr auto page_size = ENTT_SPARSE_PAGE;

    /**
     * @brief Converts an entity to its underlying type.
     * @param value The value to convert.
     * @return The integral representation of the given value.
     */
    [[nodiscard]] static constexpr entity_type to_integral(const value_type value) ENTT_NOEXCEPT {
        return static_cast<entity_type>(value);
    }

    /**
     * @brief Returns the entity part once converted to the underlying type.
     * @param value The value to convert.
     * @return The integral representation of the entity part.
     */
    [[nodiscard]] static constexpr entity_type to_entity(const value_type value) ENTT_NOEXCEPT {
        return (to_integral(value) & base_type::entity_mask);
    }

    /**
     * @brief Returns the version part once converted to the underlying type.
     * @param value The value to convert.
     * @return The integral representation of the version part.
     */
    [[nodiscard]] static constexpr version_type to_version(const value_type value) ENTT_NOEXCEPT {
        return (to_integral(value) >> base_type::entity_shift);
    }

    /**
     * @brief Constructs an identifier from its parts.
     *
     * If the version part is not provided, a tombstone is returned.<br/>
     * If the entity part is not provided, a null identifier is returned.
     *
     * @param entity The entity part of the identifier.
     * @param version The version part of the identifier.
     * @return A properly constructed identifier.
     */
    [[nodiscard]] static constexpr value_type construct(const entity_type entity, const version_type version) ENTT_NOEXCEPT {
        return value_type{(entity & base_type::entity_mask) | (static_cast<entity_type>(version) << base_type::entity_shift)};
    }

    /**
     * @brief Combines two identifiers in a single one.
     *
     * The returned identifier is a copy of the first element except for its
     * version, which is taken from the second element.
     *
     * @param lhs The identifier from which to take the entity part.
     * @param rhs The identifier from which to take the version part.
     * @return A properly constructed identifier.
     */
    [[nodiscard]] static constexpr value_type combine(const entity_type lhs, const entity_type rhs) ENTT_NOEXCEPT {
        constexpr auto mask = (base_type::version_mask << base_type::entity_shift);
        return value_type{(lhs & base_type::entity_mask) | (rhs & mask)};
    }
};





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