Struct null_t
Synopsis
#include <src/entt/entity/entity.hpp>
struct null_t
Description
Null object for all entity identifiers.
Methods
| operator Entity | Converts the null object to identifiers of any type. | |
| operator!= overload | Compares two null objects. | |
| operator!= overload | Compares a null object and an entity identifier of any type. | |
| operator== overload | Compares two null objects. | |
| operator== overload | Compares a null object and an entity identifier of any type. |
Source
Lines 99-147 in src/entt/entity/entity.hpp.
struct null_t {
/**
* @brief Converts the null object to identifiers of any type.
* @tparam Entity Type of entity identifier.
* @return The null representation for the given identifier.
*/
template<typename Entity>
[[nodiscard]] constexpr operator Entity() const ENTT_NOEXCEPT {
return Entity{entt_traits<Entity>::entity_mask};
}
/**
* @brief Compares two null objects.
* @return True in all cases.
*/
[[nodiscard]] constexpr bool operator==(const null_t &) const ENTT_NOEXCEPT {
return true;
}
/**
* @brief Compares two null objects.
* @return False in all cases.
*/
[[nodiscard]] constexpr bool operator!=(const null_t &) const ENTT_NOEXCEPT {
return false;
}
/**
* @brief Compares a null object and an entity identifier of any type.
* @tparam Entity Type of entity identifier.
* @param entity Entity identifier with which to compare.
* @return False if the two elements differ, true otherwise.
*/
template<typename Entity>
[[nodiscard]] constexpr bool operator==(const Entity &entity) const ENTT_NOEXCEPT {
return (to_integral(entity) & entt_traits<Entity>::entity_mask) == to_integral(static_cast<Entity>(*this));
}
/**
* @brief Compares a null object and an entity identifier of any type.
* @tparam Entity Type of entity identifier.
* @param entity Entity identifier with which to compare.
* @return True if the two elements differ, false otherwise.
*/
template<typename Entity>
[[nodiscard]] constexpr bool operator!=(const Entity &entity) const ENTT_NOEXCEPT {
return !(entity == *this);
}
};