Struct View

Source

pub struct View<'q, Q: Query> { /* private fields */ }

Expand description

Provides random access to the results of a query

Views borrow all components that they expose, from when the view is created until it’s dropped. As with any borrowing pattern, they should usually be short-lived to avoid conflicts with distant code that might want to borrow the same components.

Implementations§

Source §

impl<'q, Q: Query> View<'q, Q>

Source

pub fn get(&self, entity: Entity) -> Option<Q::Item<'_>>
where Q: QueryShared,

Retrieve the query results corresponding to entity

Will yield None if the entity does not exist or does not match the query.

Does not require exclusive access to the map, but is defined only for queries yielding only shared references.

Source

pub fn get_mut(&mut self, entity: Entity) -> Option<Q::Item<'_>>

Retrieve the query results corresponding to entity

Will yield None if the entity does not exist or does not match the query.

Source

pub fn contains(&self, entity: Entity) -> bool

Equivalent to get(entity).is_some(), but does not require Q: QueryShared

Source

pub unsafe fn get_unchecked(&self, entity: Entity) -> Option<Q::Item<'_>>

Like get_mut, but allows simultaneous access to multiple entities

§Safety

Must not be invoked while any unique borrow of the fetched components of entity is live.

Source

pub fn get_disjoint_mut<const N: usize>( &mut self, entities: [Entity; N], ) -> [Option<Q::Item<'_>>; N]

Like get_mut, but allows checked simultaneous access to multiple entities

For N > 3, the check for distinct entities will clone the array and take O(N log N) time.

§Examples

let mut world = World::new();

let a = world.spawn((1, 1.0));
let b = world.spawn((2, 4.0));
let c = world.spawn((3, 9.0));

let mut query = world.query_mut::<&mut i32>();
let mut view = query.view();
let [a,b,c] = view.get_disjoint_mut([a, b, c]);

assert_eq!(*a.unwrap(), 1);
assert_eq!(*b.unwrap(), 2);
assert_eq!(*c.unwrap(), 3);