Struct rs_ecs::QueryMap

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pub struct QueryMap<'q, S>where
    S: QuerySpec,
{ /* private fields */ }

Expand description

Provides random access to the entities which match a certain Query.

Implementations§

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impl<S> QueryMap<'_, S>
where S: QuerySpec,

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

Check if an Entity is present in the map.

In contrast to get, this does not require a S::Fetch: FetchShared bound. In contrast to get_mut however, a shared borrow is sufficient.

§Examples

let mut world = World::new();

let entity1 = world.alloc();
world.insert(entity1, (42_i32, 1.0_f32));

let entity2 = world.alloc();
world.insert(entity2, (2.0_f32,));

let mut query = Query::<(&i32, Option<&f32>)>::new();
let mut query = query.borrow(&world);
let query = query.map();

assert!(query.contains(entity1));
assert!(!query.contains(entity2));

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pub fn get(&self, ent: Entity) -> Option<<S::Fetch as Fetch<'_>>::Item>
where S::Fetch: FetchShared,

Access the queried components of the given Entity

Available only if the components do not include unique references.

§Examples

let mut world = World::new();

let entity1 = world.alloc();
world.insert(entity1, (42_i32, 1.0_f32));

let entity2 = world.alloc();
world.insert(entity2, (23_i32,));

let mut query = Query::<(&i32, Option<&f32>)>::new();
let mut query = query.borrow(&world);
let mut query = query.map();

let (i1, f1) = query.get(entity1).unwrap();
let (i2, f2) = query.get(entity2).unwrap();

assert_eq!(*i1, 42);
assert_eq!(f1.copied(), Some(1.0));
assert_eq!(*i2, 23);
assert_eq!(f2.copied(), None);

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pub fn get_mut(&mut self, ent: Entity) -> Option<<S::Fetch as Fetch<'_>>::Item>

Exclusively access the queried components of the given Entity

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pub fn get_many_mut<const N: usize>( &mut self, ent: [Entity; N] ) -> [Option<<S::Fetch as Fetch<'_>>::Item>; N]

Exclusively access the queried component of the given distinct entities

§Examples

let mut world = World::new();

let entity1 = world.alloc();
world.insert(entity1, (42_i32, 1.0_f32));

let entity2 = world.alloc();
world.insert(entity2, (23_i32,));

let mut query = Query::<&mut i32>::new();
let mut query = query.borrow(&world);
let mut query = query.map();

let [i1, i2] = query.get_many_mut([entity1, entity2]);

assert_eq!(*i1.unwrap(), 42);
assert_eq!(*i2.unwrap(), 23);