Struct bevy_ecs::change_detection::Ref

pub struct Ref<'a, T: ?Sized> { /* private fields */ }

Shared borrow of an entity’s component with access to change detection. Similar to Mut but is immutable and so doesn’t require unique access.

Implementations

impl<'a, T: ?Sized> Ref<'a, T>

pub fn into_inner(self) -> &'a T

Returns the reference wrapped by this type. The reference is allowed to outlive self, which makes this method more flexible than simply borrowing self.

pub fn map<U: ?Sized>(self, f: impl FnOnce(&T) -> &U) -> Ref<'a, U>

Map Ref to a different type using f.

This doesn’t do anything else than call f on the wrapped value. This is equivalent to Mut::map_unchanged.

pub fn new( value: &'a T, added: &'a Tick, changed: &'a Tick, last_run: Tick, this_run: Tick ) -> Ref<'a, T>

Create a new Ref using provided values.

This is an advanced feature, Refs are designed to be created by engine-internal code and consumed by end-user code.

• value - The value wrapped by Ref.
• added - A Tick that stores the tick when the wrapped value was created.
• changed - A Tick that stores the last time the wrapped value was changed.
• last_run - A Tick, occurring before this_run, which is used as a reference to determine whether the wrapped value is newly added or changed.
• this_run - A Tick corresponding to the current point in time – “now”.

Trait Implementations

impl<'a, T> AsRef<T> for Ref<'a, T>

fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.

impl<'a, T> Debug for Ref<'a, T>where T: Debug + ?Sized,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a, T: ?Sized> Deref for Ref<'a, T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<'a, T: ?Sized> DetectChanges for Ref<'a, T>

fn is_added(&self) -> bool

Returns true if this value was added after the system last ran.

fn is_changed(&self) -> bool

Returns true if this value was added or mutably dereferenced either since the last time the system ran or, if the system never ran, since the beginning of the program.

fn last_changed(&self) -> Tick

Returns the change tick recording the time this data was most recently changed.

impl<'a, T: ?Sized> From<Mut<'a, T>> for Ref<'a, T>

fn from(mut_ref: Mut<'a, T>) -> Self

Converts to this type from the input type.

impl<'w, 'a, T> IntoIterator for &'a Ref<'w, T>where &'a T: IntoIterator,

type Item = <&'a T as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <&'a T as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<'__w, T: Component> WorldQuery for Ref<'__w, T>

SAFETY: Self is the same as Self::ReadOnly

type Fetch<'w> = RefFetch<'w, T>

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

type Item<'w> = Ref<'w, T>

The item returned by this WorldQuery

type ReadOnly = Ref<'__w, T>

The read-only variant of this WorldQuery, which satisfies the ReadOnlyWorldQuery trait.

type State = 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: Ref<'wlong, T>) -> Ref<'wshort, T>

This function manually implements subtyping for the query items.

const IS_DENSE: bool = _

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.

const IS_ARCHETYPAL: bool = true

Returns true if (and only if) this Fetch relies strictly on archetypes to limit which components are accessed by the Query.

unsafe fn init_fetch<'w>( world: UnsafeWorldCell<'w>, component_id: &ComponentId, last_run: Tick, this_run: Tick ) -> RefFetch<'w, T>

Creates a new instance of this fetch.

unsafe fn set_archetype<'w>( fetch: &mut RefFetch<'w, T>, component_id: &ComponentId, _archetype: &'w Archetype, table: &'w 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 RefFetch<'w, T>, component_id: &ComponentId, table: &'w Table )

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

unsafe fn fetch<'w>( fetch: &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( component_id: &ComponentId, access: &mut FilteredAccess<ComponentId> )

Adds any component accesses used by this WorldQuery to access.

fn update_archetype_component_access( component_id: &ComponentId, archetype: &Archetype, access: &mut Access<ArchetypeComponentId> )

For the given archetype, adds any component accessed used by this WorldQuery to access.

fn init_state(world: &mut World) -> ComponentId

Creates and initializes a State for this WorldQuery type.

fn matches_component_set( state: &ComponentId, set_contains_id: &impl Fn(ComponentId) -> bool ) -> bool

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

unsafe fn filter_fetch( fetch: &mut Self::Fetch<'_>, entity: Entity, table_row: TableRow ) -> bool

Safety

impl<'__w, T: Component> ReadOnlyWorldQuery for Ref<'__w, T>

SAFETY: access is read only