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- #ifndef ENTT_ENTITY_HELPER_HPP
- #define ENTT_ENTITY_HELPER_HPP
-
- #include <type_traits>
- #include "../config/config.h"
- #include "../core/fwd.hpp"
- #include "../core/type_traits.hpp"
- #include "../signal/delegate.hpp"
- #include "fwd.hpp"
- #include "registry.hpp"
-
- namespace entt {
-
- /**
- * @brief Converts a registry to a view.
- * @tparam Entity A valid entity type (see entt_traits for more details).
- */
- template<typename Entity>
- struct as_view {
- /*! @brief Underlying entity identifier. */
- using entity_type = std::remove_const_t<Entity>;
- /*! @brief Type of registry to convert. */
- using registry_type = constness_as_t<basic_registry<entity_type>, Entity>;
-
- /**
- * @brief Constructs a converter for a given registry.
- * @param source A valid reference to a registry.
- */
- as_view(registry_type &source) ENTT_NOEXCEPT: reg{source} {}
-
- /**
- * @brief Conversion function from a registry to a view.
- * @tparam Exclude Types of components used to filter the view.
- * @tparam Component Type of components used to construct the view.
- * @return A newly created view.
- */
- template<typename Exclude, typename... Component>
- operator basic_view<entity_type, get_t<Component...>, Exclude>() const {
- return reg.template view<Component...>(Exclude{});
- }
-
- private:
- registry_type ®
- };
-
- /**
- * @brief Deduction guide.
- * @tparam Entity A valid entity type (see entt_traits for more details).
- */
- template<typename Entity>
- as_view(basic_registry<Entity> &) -> as_view<Entity>;
-
- /**
- * @brief Deduction guide.
- * @tparam Entity A valid entity type (see entt_traits for more details).
- */
- template<typename Entity>
- as_view(const basic_registry<Entity> &) -> as_view<const Entity>;
-
- /**
- * @brief Converts a registry to a group.
- * @tparam Entity A valid entity type (see entt_traits for more details).
- */
- template<typename Entity>
- struct as_group {
- /*! @brief Underlying entity identifier. */
- using entity_type = std::remove_const_t<Entity>;
- /*! @brief Type of registry to convert. */
- using registry_type = constness_as_t<basic_registry<entity_type>, Entity>;
-
- /**
- * @brief Constructs a converter for a given registry.
- * @param source A valid reference to a registry.
- */
- as_group(registry_type &source) ENTT_NOEXCEPT: reg{source} {}
-
- /**
- * @brief Conversion function from a registry to a group.
- * @tparam Get Types of components observed by the group.
- * @tparam Exclude Types of components used to filter the group.
- * @tparam Owned Types of components owned by the group.
- * @return A newly created group.
- */
- template<typename Get, typename Exclude, typename... Owned>
- operator basic_group<entity_type, owned_t<Owned...>, Get, Exclude>() const {
- if constexpr(std::is_const_v<registry_type>) {
- return reg.template group_if_exists<Owned...>(Get{}, Exclude{});
- } else {
- return reg.template group<Owned...>(Get{}, Exclude{});
- }
- }
-
- private:
- registry_type ®
- };
-
- /**
- * @brief Deduction guide.
- * @tparam Entity A valid entity type (see entt_traits for more details).
- */
- template<typename Entity>
- as_group(basic_registry<Entity> &) -> as_group<Entity>;
-
- /**
- * @brief Deduction guide.
- * @tparam Entity A valid entity type (see entt_traits for more details).
- */
- template<typename Entity>
- as_group(const basic_registry<Entity> &) -> as_group<const Entity>;
-
- /**
- * @brief Helper to create a listener that directly invokes a member function.
- * @tparam Member Member function to invoke on a component of the given type.
- * @tparam Entity A valid entity type (see entt_traits for more details).
- * @param reg A registry that contains the given entity and its components.
- * @param entt Entity from which to get the component.
- */
- template<auto Member, typename Entity = entity>
- void invoke(basic_registry<Entity> ®, const Entity entt) {
- static_assert(std::is_member_function_pointer_v<decltype(Member)>, "Invalid pointer to non-static member function");
- delegate<void(basic_registry<Entity> &, const Entity)> func;
- func.template connect<Member>(reg.template get<member_class_t<decltype(Member)>>(entt));
- func(reg, entt);
- }
-
- /**
- * @brief Returns the entity associated with a given component.
- *
- * @warning
- * Currently, this function only works correctly with the default pool as it
- * makes assumptions about how the components are laid out.
- *
- * @tparam Entity A valid entity type (see entt_traits for more details).
- * @tparam Component Type of component.
- * @param reg A registry that contains the given entity and its components.
- * @param instance A valid component instance.
- * @return The entity associated with the given component.
- */
- template<typename Entity, typename Component>
- Entity to_entity(const basic_registry<Entity> ®, const Component &instance) {
- const auto &storage = reg.template storage<Component>();
- const typename basic_registry<Entity>::base_type &base = storage;
- const auto *addr = std::addressof(instance);
-
- for(auto it = base.rbegin(), last = base.rend(); it < last; it += ENTT_PACKED_PAGE) {
- if(const auto dist = (addr - std::addressof(storage.get(*it))); dist >= 0 && dist < ENTT_PACKED_PAGE) {
- return *(it + dist);
- }
- }
-
- return null;
- }
-
- } // namespace entt
-
- #endif
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