Struct FilteredEntityRef

pub struct FilteredEntityRef<'w> { /* private fields */ }

Provides read-only access to a single entity and some of its components defined by the contained Access.

To define the access when used as a QueryData, use a QueryBuilder or QueryParamBuilder. The FilteredEntityRef must be the entire QueryData, and not nested inside a tuple with other data.

// This gives the `FilteredEntityRef` access to `&A`.
let mut query = QueryBuilder::<FilteredEntityRef>::new(&mut world)
    .data::<&A>()
    .build();

let filtered_entity: FilteredEntityRef = query.single(&mut world);
let component: &A = filtered_entity.get().unwrap();

// Here `FilteredEntityRef` is nested in a tuple, so it does not have access to `&A`.
let mut query = QueryBuilder::<(Entity, FilteredEntityRef)>::new(&mut world)
    .data::<&A>()
    .build();

let (_, filtered_entity) = query.single(&mut world);
assert!(filtered_entity.get::<A>().is_none());

Implementations

impl<'w> FilteredEntityRef<'w>

pub fn id(&self) -> Entity

Returns the ID of the current entity.

pub fn location(&self) -> EntityLocation

Gets metadata indicating the location where the current entity is stored.

pub fn archetype(&self) -> &Archetype

Returns the archetype that the current entity belongs to.

pub fn access(&self) -> &Access<ComponentId>

Returns a reference to the underlying Access.

pub fn contains<T: Component>(&self) -> bool

Returns true if the current entity has a component of type T. Otherwise, this returns false.

Notes

If you do not know the concrete type of a component, consider using Self::contains_id or Self::contains_type_id.

pub fn contains_id(&self, component_id: ComponentId) -> bool

Returns true if the current entity has a component identified by component_id. Otherwise, this returns false.

Notes

• If you know the concrete type of the component, you should prefer Self::contains.
• If you know the component’s TypeId but not its ComponentId, consider using Self::contains_type_id.

pub fn contains_type_id(&self, type_id: TypeId) -> bool

Returns true if the current entity has a component with the type identified by type_id. Otherwise, this returns false.

Notes

• If you know the concrete type of the component, you should prefer Self::contains.
• If you have a ComponentId instead of a TypeId, consider using Self::contains_id.

pub fn get<T: Component>(&self) -> Option<&'w T>

Gets access to the component of type T for the current entity. Returns None if the entity does not have a component of type T.

pub fn get_ref<T: Component>(&self) -> Option<Ref<'w, T>>

Gets access to the component of type T for the current entity, including change detection information as a Ref.

Returns None if the entity does not have a component of type T.

pub fn get_change_ticks<T: Component>(&self) -> Option<ComponentTicks>

Retrieves the change ticks for the given component. This can be useful for implementing change detection in custom runtimes.

pub fn get_change_ticks_by_id( &self, component_id: ComponentId, ) -> Option<ComponentTicks>

Retrieves the change ticks for the given ComponentId. This can be useful for implementing change detection in custom runtimes.

You should prefer to use the typed API Self::get_change_ticks where possible and only use this in cases where the actual component types are not known at compile time.

pub fn get_by_id(&self, component_id: ComponentId) -> Option<Ptr<'w>>

Gets the component of the given ComponentId from the entity.

You should prefer to use the typed API Self::get where possible and only use this in cases where the actual component types are not known at compile time.

Unlike FilteredEntityRef::get, this returns a raw pointer to the component, which is only valid while the FilteredEntityRef is alive.

Trait Implementations

impl<'w> Clone for FilteredEntityRef<'w>

fn clone(&self) -> FilteredEntityRef<'w>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> From<&'a EntityMut<'_>> for FilteredEntityRef<'a>

fn from(entity: &'a EntityMut<'_>) -> Self

Converts to this type from the input type.

impl<'a> From<&'a EntityRef<'_>> for FilteredEntityRef<'a>

fn from(entity: &'a EntityRef<'_>) -> Self

Converts to this type from the input type.

impl<'a> From<&'a EntityWorldMut<'_>> for FilteredEntityRef<'a>

fn from(entity: &'a EntityWorldMut<'_>) -> Self

Converts to this type from the input type.

impl<'a> From<&'a FilteredEntityMut<'_>> for FilteredEntityRef<'a>

fn from(entity_mut: &'a FilteredEntityMut<'_>) -> Self

Converts to this type from the input type.

impl<'a> From<EntityMut<'a>> for FilteredEntityRef<'a>

fn from(entity: EntityMut<'a>) -> Self

Converts to this type from the input type.

impl<'a> From<EntityRef<'a>> for FilteredEntityRef<'a>

fn from(entity: EntityRef<'a>) -> Self

Converts to this type from the input type.

impl<'a> From<EntityWorldMut<'a>> for FilteredEntityRef<'a>

fn from(entity: EntityWorldMut<'a>) -> Self

Converts to this type from the input type.

impl<'w> From<FilteredEntityMut<'w>> for FilteredEntityRef<'w>

fn from(entity_mut: FilteredEntityMut<'w>) -> Self

Converts to this type from the input type.

impl<'a> QueryData for FilteredEntityRef<'a>

SAFETY: Self is the same as Self::ReadOnly

type ReadOnly = FilteredEntityRef<'a>

The read-only variant of this QueryData, which satisfies the ReadOnlyQueryData trait.

impl<'a> TryFrom<&'a FilteredEntityRef<'_>> for EntityRef<'a>

type Error = TryFromFilteredError

The type returned in the event of a conversion error.

fn try_from(value: &'a FilteredEntityRef<'_>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> TryFrom<FilteredEntityRef<'a>> for EntityRef<'a>

type Error = TryFromFilteredError

The type returned in the event of a conversion error.

fn try_from(value: FilteredEntityRef<'a>) -> Result<Self, Self::Error>

Performs the conversion.

impl<'a> WorldQuery for FilteredEntityRef<'a>

SAFETY: The accesses of Self::ReadOnly are a subset of the accesses of Self

const IS_DENSE: bool = false

Returns true if (and only if) every table of every archetype matched by this fetch contains all of the matched components. This is used to select a more efficient “table iterator” for “dense” queries. If this returns true, WorldQuery::set_table must be used before WorldQuery::fetch can be called for iterators. If this returns false, WorldQuery::set_archetype must be used before WorldQuery::fetch can be called for iterators.

type Fetch<'w> = (UnsafeWorldCell<'w>, Access<ComponentId>)

Per archetype/table state used by this WorldQuery to fetch Self::Item

type Item<'w> = FilteredEntityRef<'w>

The item returned by this WorldQuery For QueryData this will be the item returned by the query. For QueryFilter this will be either (), or a bool indicating whether the entity should be included or a tuple of such things.

type State = FilteredAccess<ComponentId>

State used to construct a Self::Fetch. This will be cached inside QueryState, so it is best to move as much data / computation here as possible to reduce the cost of constructing Self::Fetch.

fn shrink<'wlong: 'wshort, 'wshort>( item: Self::Item<'wlong>, ) -> Self::Item<'wshort>

This function manually implements subtyping for the query items.

fn shrink_fetch<'wlong: 'wshort, 'wshort>( fetch: Self::Fetch<'wlong>, ) -> Self::Fetch<'wshort>

This function manually implements subtyping for the query fetches.

unsafe fn init_fetch<'w>( world: UnsafeWorldCell<'w>, _state: &Self::State, _last_run: Tick, _this_run: Tick, ) -> Self::Fetch<'w>

Creates a new instance of this fetch.

unsafe fn set_archetype<'w>( fetch: &mut Self::Fetch<'w>, state: &Self::State, _: &'w Archetype, _table: &Table, )

Adjusts internal state to account for the next Archetype. This will always be called on archetypes that match this WorldQuery.

unsafe fn set_table<'w>( fetch: &mut Self::Fetch<'w>, state: &Self::State, _: &'w Table, )

Adjusts internal state to account for the next Table. This will always be called on tables that match this WorldQuery.

fn set_access<'w>(state: &mut Self::State, access: &FilteredAccess<ComponentId>)

Sets available accesses for implementors with dynamic access such as FilteredEntityRef or FilteredEntityMut.

unsafe fn fetch<'w>( (world, access): &mut Self::Fetch<'w>, entity: Entity, _table_row: TableRow, ) -> Self::Item<'w>

Fetch Self::Item for either the given entity in the current Table, or for the given entity in the current Archetype. This must always be called after WorldQuery::set_table with a table_row in the range of the current Table or after WorldQuery::set_archetype with a entity in the current archetype.

fn update_component_access( state: &Self::State, filtered_access: &mut FilteredAccess<ComponentId>, )

Adds any component accesses used by this WorldQuery to access.

fn init_state(_world: &mut World) -> Self::State

Creates and initializes a State for this WorldQuery type.

fn get_state(_components: &Components) -> Option<Self::State>

Attempts to initialize a State for this WorldQuery type using read-only access to Components.

fn matches_component_set( _state: &Self::State, _set_contains_id: &impl Fn(ComponentId) -> bool, ) -> bool

Returns true if this query matches a set of components. Otherwise, returns false.

impl ReadOnlyQueryData for FilteredEntityRef<'_>

SAFETY: Access is read-only.