[Merged by Bors] - Add Query::contains #3090
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| Original file line number | Diff line number | Diff line change |
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@@ -975,6 +975,35 @@ where | |
| self.state | ||
| .is_empty(self.world, self.last_change_tick, self.change_tick) | ||
| } | ||
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| /// Returns `true` if the given [`Entity`] matches the query. | ||
| /// | ||
| /// # Example | ||
| /// | ||
| /// ``` | ||
| /// # use bevy_ecs::prelude::*; | ||
| /// # | ||
| /// # #[derive(Component)] | ||
| /// # struct InRange; | ||
| /// # | ||
| /// # struct Target { | ||
| /// # entity: Entity, | ||
| /// # } | ||
| /// # | ||
| /// fn targeting_system(in_range_query: Query<&InRange>, target: Res<Target>) { | ||
| /// if in_range_query.contains(target.entity) { | ||
| /// println!("Bam!") | ||
| /// } | ||
| /// } | ||
| /// # targeting_system.system(); | ||
| /// ``` | ||
| #[inline] | ||
| pub fn contains(&self, entity: Entity) -> bool | ||
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There was a problem hiding this comment. I'm wondering if its worth taking a chunk from for example, something like this in state.rs: pub fn contains<'w, 's>(&'s self, world: &'w World, entity: Entity) -> bool {
let location = world.entities.get(entity);
if let Some(location) = location {
return self
.matched_archetypes
.contains(location.archetype_id.index());
}
false
}and then call There was a problem hiding this comment. as @TheRawMeatball said earlier
There was a problem hiding this comment. the above code doesn't call any unsafe functions and it would be easier enough to write a test to verify it works. There was a problem hiding this comment. example: #[test]
fn query_contains_entity() {
fn without_entity(entity: Res<Entity>, empty: Query<&A>) {
assert!(!empty.contains(*entity));
}
fn with_entity(entity: Res<Entity>, not_empty: Query<&A>) {
assert!(not_empty.contains(*entity));
}
let mut world = World::default();
let entity = world.spawn().insert(B).id();
world.insert_resource(entity);
let mut without_entity = without_entity.system();
without_entity.initialize(&mut world);
without_entity.run((), &mut world);
let entity = world.spawn().insert(A).id();
world.insert_resource(entity);
let mut with_entity = with_entity.system();
with_entity.initialize(&mut world);
with_entity.run((), &mut world);
}There was a problem hiding this comment. I thought we would want to handle query filters though? |
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| where | ||
| Q::Fetch: ReadOnlyFetch, | ||
| { | ||
| self.get(entity).is_ok() | ||
| } | ||
| } | ||
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| /// An error that occurs when retrieving a specific [`Entity`]'s component from a [`Query`] | ||
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I don't propose that you take any action on this comment, just noting down my thoughts.
By a strict reading of these docs, a valid implementation of this function would be
{true}; we don't specify the behaviour if the condition is false. It is however intended to be read asif and only if.However, this fits the pattern of documentation in
std, e.g.Vec::contains. I tried to find a rust-lang/rust issue on these doc items, but failed to do so.