Struct aery::edges::Root

pub struct Root<R: Relation>(/* private fields */);

Filter to find roots of a relationship graph. An entity is a root of R if:

• It is targeted by atleast one other entity via R.
• It does not target any other entity via R.

Trait Implementations

impl<R: Relation> QueryFilter for Root<R>

const IS_ARCHETYPAL: bool = true

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

unsafe fn filter_fetch<'__w>( _fetch: &mut <Self as WorldQuery>::Fetch<'__w>, _entity: Entity, _table_row: TableRow ) -> bool

Safety

impl<R: Relation> WorldQuery for Root<R>

unsafe fn set_archetype<'__w>( _fetch: &mut <Self as WorldQuery>::Fetch<'__w>, _state: &Self::State, _archetype: &'__w Archetype, _table: &'__w Table )

SAFETY: we call set_archetype for each member that implements Fetch

unsafe fn set_table<'__w>( _fetch: &mut <Self as WorldQuery>::Fetch<'__w>, _state: &Self::State, _table: &'__w Table )

SAFETY: we call set_table for each member that implements Fetch

unsafe fn fetch<'__w>( _fetch: &mut <Self as WorldQuery>::Fetch<'__w>, _entity: Entity, _table_row: TableRow ) -> <Self as WorldQuery>::Item<'__w>

SAFETY: we call fetch for each member that implements Fetch.

type Item<'__w> = RootItem<'__w, R>

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 Fetch<'__w> = RootFetch<'__w, R>

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

type State = RootState<R>

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: <Root<R> as WorldQuery>::Item<'__wlong> ) -> <Root<R> as WorldQuery>::Item<'__wshort>

This function manually implements subtyping for the query items.

unsafe fn init_fetch<'__w>( _world: UnsafeWorldCell<'__w>, state: &Self::State, _last_run: Tick, _this_run: Tick ) -> <Self as WorldQuery>::Fetch<'__w>

Creates a new instance of this fetch.

const IS_DENSE: bool = true

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.

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

Adds any component accesses used by this WorldQuery to access.

fn init_state(world: &mut World) -> RootState<R>

Creates and initializes a State for this WorldQuery type.

fn get_state(world: &World) -> Option<RootState<R>>

Attempts to initializes a State for this WorldQuery type.

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.

fn set_access(_state: &mut Self::State, _access: &FilteredAccess<ComponentId>)

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