Struct hecs::QueryBorrow

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pub struct QueryBorrow<'w, Q: Query> { /* private fields */ }

Expand description

A borrow of a World sufficient to execute the query Q

Note that borrows are not released until this object is dropped.

Implementations

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impl<'w, Q: Query> QueryBorrow<'w, Q>

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pub fn iter(&mut self) -> QueryIter<'_, Q>ⓘNotable traits for QueryIter<'q, Q>`impl<'q, Q: Query> Iterator for QueryIter<'q, Q> type Item = (Entity, QueryItem<'q, Q>);`

Execute the query

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pub fn view(&mut self) -> View<'_, Q>

Provide random access to the query results

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pub fn iter_batched(&mut self, batch_size: u32) -> BatchedIter<'_, Q>ⓘNotable traits for BatchedIter<'q, Q>`impl<'q, Q: Query> Iterator for BatchedIter<'q, Q> type Item = Batch<'q, Q>;`

Like iter, but returns child iterators of at most batch_size elements

Useful for distributing work over a threadpool.

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pub fn with<T: Component>(self) -> QueryBorrow<'w, With<T, Q>>

Transform the query into one that requires a certain component without borrowing it

This can be useful when the component needs to be borrowed elsewhere and it isn’t necessary for the iterator to expose its data directly.

Equivalent to using a query type wrapped in With.

Example

let mut world = World::new();
let a = world.spawn((123, true, "abc"));
let b = world.spawn((456, false));
let c = world.spawn((42, "def"));
let entities = world.query::<&i32>()
    .with::<bool>()
    .iter()
    .map(|(e, &i)| (e, i)) // Copy out of the world
    .collect::<Vec<_>>();
assert!(entities.contains(&(a, 123)));
assert!(entities.contains(&(b, 456)));

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pub fn without<T: Component>(self) -> QueryBorrow<'w, Without<T, Q>>

Transform the query into one that skips entities having a certain component

Equivalent to using a query type wrapped in Without.

Example

let mut world = World::new();
let a = world.spawn((123, true, "abc"));
let b = world.spawn((456, false));
let c = world.spawn((42, "def"));
let entities = world.query::<&i32>()
    .without::<bool>()
    .iter()
    .map(|(e, &i)| (e, i)) // Copy out of the world
    .collect::<Vec<_>>();
assert_eq!(entities, &[(c, 42)]);