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Update Query methods documentation (#5742)

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# Objective

- Increase consistency across documentation of `Query` methods.
- Fixes #5506

## Solution

- See #4989. This PR is derived from it. It just includes changes to the `Query` methods' docs.
This commit is contained in:
Federico Rinaldi 2022-09-02 16:33:19 +00:00
parent 26d30fe412
commit dfeb63e7b8
1 changed files with 220 additions and 150 deletions
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370
crates/bevy_ecs/src/system/query.rs
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@ -302,7 +302,7 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Downgrades all data accessed in this query to a read-only form.
/// Returns another `Query` from this that fetches the read-only version of the query items.
///
/// For example, `Query<(&mut A, &B, &mut C), With<D>>` will become `Query<(&A, &B, &C), With<D>>`.
/// This can be useful when working around the borrow checker,
@ -320,15 +320,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns an [`Iterator`] over the query results.
///
/// This can only return immutable data (mutable data will be cast to an immutable form).
/// See [`Self::iter_mut`] for queries that contain at least one mutable component.
/// Returns an [`Iterator`] over the read-only query items.
///
/// # Example
///
/// Here, the `report_names_system` iterates over the `Player` component of every entity
/// that contains it:
/// Here, the `report_names_system` iterates over the `Player` component of every entity that contains it:
///
/// ```
/// # use bevy_ecs::prelude::*;
@ -343,6 +339,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(report_names_system);
/// ```
///
/// # See also
///
/// - [`iter_mut`](Self::iter_mut) for mutable query items.
/// - [`for_each`](Self::for_each) for the closure based alternative.
#[inline]
pub fn iter(&self) -> QueryIter<'_, 's, Q::ReadOnly, F::ReadOnly> {
// SAFETY: system runs without conflicts with other systems.
@ -356,12 +357,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns an [`Iterator`] over the query results.
/// Returns an [`Iterator`] over the query items.
///
/// # Example
///
/// Here, the `gravity_system` iterates over the `Velocity` component of every entity in
/// the world that contains it in order to update it:
/// Here, the `gravity_system` updates the `Velocity` component of every entity that contains it:
///
/// ```
/// # use bevy_ecs::prelude::*;
@ -376,6 +376,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(gravity_system);
/// ```
///
/// # See also
///
/// - [`iter`](Self::iter) for read-only query items.
/// - [`for_each_mut`](Self::for_each_mut) for the closure based alternative.
#[inline]
pub fn iter_mut(&mut self) -> QueryIter<'_, 's, Q, F> {
// SAFETY: system runs without conflicts with other systems.
@ -386,13 +391,25 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns an [`Iterator`] over all possible combinations of `K` query results without repetition.
/// This can only return immutable data
/// Returns a [`QueryCombinationIter`] over all combinations of `K` read-only query items without repetition.
///
/// For permutations of size `K` of query returning `N` results, you will get:
/// - if `K == N`: one permutation of all query results
/// - if `K < N`: all possible `K`-sized combinations of query results, without repetition
/// - if `K > N`: empty set (no `K`-sized combinations exist)
/// # Example
///
/// ```
/// # use bevy_ecs::prelude::*;
/// # #[derive(Component)]
/// # struct ComponentA;
/// #
/// fn some_system(query: Query<&ComponentA>) {
/// for [a1, a2] in query.iter_combinations() {
/// // ...
/// }
/// }
/// ```
///
/// # See also
///
/// - [`iter_combinations_mut`](Self::iter_combinations_mut) for mutable query item combinations.
#[inline]
pub fn iter_combinations<const K: usize>(
&self,
@ -408,28 +425,25 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Iterates over all possible combinations of `K` query results without repetition.
/// Returns a [`QueryCombinationIter`] over all combinations of `K` query items without repetition.
///
/// The returned value is not an `Iterator`, because that would lead to aliasing of mutable references.
/// In order to iterate it, use `fetch_next` method with `while let Some(..)` loop pattern.
/// # Example
///
/// ```
/// # use bevy_ecs::prelude::*;
/// #[derive(Component)]
/// # struct A;
/// # fn some_system(mut query: Query<&mut A>) {
/// // iterate using `fetch_next` in while loop
/// let mut combinations = query.iter_combinations_mut();
/// while let Some([mut a, mut b]) = combinations.fetch_next() {
/// // mutably access components data
/// # #[derive(Component)]
/// # struct ComponentA;
/// fn some_system(mut query: Query<&mut ComponentA>) {
/// let mut combinations = query.iter_combinations_mut();
/// while let Some([mut a1, mut a2]) = combinations.fetch_next() {
/// // mutably access components data
/// }
/// }
/// # }
/// ```
///
/// There is no `for_each` method, because it cannot be safely implemented
/// due to a [compiler bug](https://github.com/rust-lang/rust/issues/62529).
/// # See also
///
/// For immutable access see [`Query::iter_combinations`].
/// - [`iter_combinations`](Self::iter_combinations) for read-only query item combinations.
#[inline]
pub fn iter_combinations_mut<const K: usize>(
&mut self,
@ -445,19 +459,18 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns an [`Iterator`] over the query results of a list of [`Entity`]'s.
/// Returns an [`Iterator`] over the read-only query items generated from an [`Entity`] list.
///
/// This can only return immutable data (mutable data will be cast to an immutable form).
/// See [`Self::iter_many_mut`] for queries that contain at least one mutable component.
/// # Example
///
/// # Examples
/// ```
/// # use bevy_ecs::prelude::*;
/// #[derive(Component)]
/// struct Counter {
/// value: i32
/// }
///
/// # #[derive(Component)]
/// # struct Counter {
/// # value: i32
/// # }
/// #
/// // A component containing an entity list.
/// #[derive(Component)]
/// struct Friends {
/// list: Vec<Entity>,
@ -475,6 +488,10 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(system);
/// ```
///
/// # See also
///
/// - [`iter_many_mut`](Self::iter_many_mut) to get mutable query items.
#[inline]
pub fn iter_many<EntityList: IntoIterator>(
&self,
@ -495,7 +512,8 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Calls a closure on each result of [`Query`] where the entities match.
/// Returns an [`Iterator`] over the query items generated from an [`Entity`] list.
///
/// # Examples
///
/// ```
@ -544,12 +562,16 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns an [`Iterator`] over the query results.
/// Returns an [`Iterator`] over the query items.
///
/// # Safety
///
/// This function makes it possible to violate Rust's aliasing guarantees. You must make sure
/// this call does not result in multiple mutable references to the same component
/// This function makes it possible to violate Rust's aliasing guarantees.
/// You must make sure this call does not result in multiple mutable references to the same component.
///
/// # See also
///
/// - [`iter`](Self::iter) and [`iter_mut`](Self::iter_mut) for the safe versions.
#[inline]
pub unsafe fn iter_unsafe(&self) -> QueryIter<'_, 's, Q, F> {
// SEMI-SAFETY: system runs without conflicts with other systems.
@ -558,12 +580,16 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
.iter_unchecked_manual(self.world, self.last_change_tick, self.change_tick)
}
/// Iterates over all possible combinations of `K` query results without repetition.
/// See [`Query::iter_combinations`].
/// Iterates over all possible combinations of `K` query items without repetition.
///
/// # Safety
/// This allows aliased mutability. You must make sure this call does not result in multiple
/// mutable references to the same component
///
/// This allows aliased mutability.
/// You must make sure this call does not result in multiple mutable references to the same component.
///
/// # See also
///
/// - [`iter_combinations`](Self::iter_combinations) and [`iter_combinations_mut`](Self::iter_combinations_mut) for the safe versions.
#[inline]
pub unsafe fn iter_combinations_unsafe<const K: usize>(
&self,
@ -577,14 +603,17 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
)
}
/// Returns an [`Iterator`] over the query results of a list of [`Entity`]'s.
///
/// If you want safe mutable access to query results of a list of [`Entity`]'s. See [`Self::iter_many_mut`].
/// Returns an [`Iterator`] over the query items generated from an [`Entity`] list.
///
/// # Safety
///
/// This allows aliased mutability and does not check for entity uniqueness.
/// You must make sure this call does not result in multiple mutable references to the same component.
/// Particular care must be taken when collecting the data (rather than iterating over it one item at a time) such as via `[Iterator::collect()]`.
/// Particular care must be taken when collecting the data (rather than iterating over it one item at a time) such as via [`Iterator::collect`].
///
/// # See also
///
/// - [`iter_many_mut`](Self::iter_many_mut) to safely access the query items.
pub unsafe fn iter_many_unsafe<EntityList: IntoIterator>(
&self,
entities: EntityList,
@ -600,15 +629,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
)
}
/// Runs `f` on each query result. This is faster than the equivalent iter() method, but cannot
/// be chained like a normal [`Iterator`].
///
/// This can only pass in immutable data, see [`Self::for_each_mut`] for mutable access.
/// Runs `f` on each read-only query item.
///
/// # Example
///
/// Here, the `report_names_system` iterates over the `Player` component of every entity
/// that contains it:
/// Here, the `report_names_system` iterates over the `Player` component of every entity that contains it:
///
/// ```
/// # use bevy_ecs::prelude::*;
@ -623,6 +648,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(report_names_system);
/// ```
///
/// # See also
///
/// - [`for_each_mut`](Self::for_each_mut) to operate on mutable query items.
/// - [`iter`](Self::iter) for the iterator based alternative.
#[inline]
pub fn for_each<'this>(&'this self, f: impl FnMut(ROQueryItem<'this, Q>)) {
// SAFETY: system runs without conflicts with other systems.
@ -637,13 +667,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
};
}
/// Runs `f` on each query result. This is faster than the equivalent iter() method, but cannot
/// be chained like a normal [`Iterator`].
/// Runs `f` on each query item.
///
/// # Example
///
/// Here, the `gravity_system` iterates over the `Velocity` component of every entity in
/// the world that contains it in order to update it:
/// Here, the `gravity_system` updates the `Velocity` component of every entity that contains it:
///
/// ```
/// # use bevy_ecs::prelude::*;
@ -658,6 +686,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(gravity_system);
/// ```
///
/// # See also
///
/// - [`for_each`](Self::for_each) to operate on read-only query items.
/// - [`iter_mut`](Self::iter_mut) for the iterator based alternative.
#[inline]
pub fn for_each_mut<'a>(&'a mut self, f: impl FnMut(QueryItem<'a, Q>)) {
// SAFETY: system runs without conflicts with other systems. same-system queries have runtime
@ -672,10 +705,9 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
};
}
/// Runs `f` on each query result in parallel using the [`World`]'s [`ComputeTaskPool`].
/// Runs `f` on each read-only query item in parallel.
///
/// This can only be called for immutable data, see [`Self::par_for_each_mut`] for
/// mutable access.
/// Parallelization is achieved by using the [`World`]'s [`ComputeTaskPool`].
///
/// # Tasks and batch size
///
@ -687,16 +719,16 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// Rule of thumb: If the function body is (mostly) computationally expensive but there are not many items, a small batch size (=more batches) may help to even out the load.
/// If the body is computationally cheap and you have many items, a large batch size (=fewer batches) avoids spawning additional futures that don't help to even out the load.
///
/// # Arguments
///
///* `batch_size` - The number of batches to spawn
///* `f` - The function to run on each item in the query
/// [`ComputeTaskPool`]: bevy_tasks::prelude::ComputeTaskPool
///
/// # Panics
/// The [`ComputeTaskPool`] is not initialized. If using this from a query that is being
/// initialized and run from the ECS scheduler, this should never panic.
///
/// [`ComputeTaskPool`]: bevy_tasks::prelude::ComputeTaskPool
/// This method panics if the [`ComputeTaskPool`] resource is added to the `World` before using this method.
/// If using this from a query that is being initialized and run from the [`Schedule`](crate::schedule::Schedule), this never panics.
///
/// # See also
///
/// - [`par_for_each_mut`](Self::par_for_each_mut) for operating on mutable query items.
#[inline]
pub fn par_for_each<'this>(
&'this self,
@ -716,14 +748,20 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
};
}
/// Runs `f` on each query result in parallel using the [`World`]'s [`ComputeTaskPool`].
/// See [`Self::par_for_each`] for more details.
/// Runs `f` on each read-only query item in parallel.
///
/// Parallelization is achieved by using the [`World`]'s [`ComputeTaskPool`].
///
/// # Panics
/// The [`ComputeTaskPool`] is not initialized. If using this from a query that is being
/// initialized and run from the ECS scheduler, this should never panic.
///
/// This method panics if the [`ComputeTaskPool`] resource is added to the `World` before using this method.
/// If using this from a query that is being initialized and run from the [`Schedule`](crate::schedule::Schedule), this never panics.
///
/// [`ComputeTaskPool`]: bevy_tasks::prelude::ComputeTaskPool
///
/// # See also
///
/// - [`par_for_each`](Self::par_for_each) for more usage details.
#[inline]
pub fn par_for_each_mut<'a>(
&'a mut self,
@ -743,18 +781,13 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
};
}
/// Returns the query result for the given [`Entity`].
/// Returns the read-only query item for the given [`Entity`].
///
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is
/// returned instead.
///
/// This can only return immutable data (mutable data will be cast to an immutable form).
/// See [`get_mut`](Self::get_mut) for queries that contain at least one mutable component.
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is returned instead.
///
/// # Example
///
/// Here, `get` is used to retrieve the exact query result of the entity specified by the
/// `SelectedCharacter` resource.
/// Here, `get` is used to retrieve the exact query item of the entity specified by the `SelectedCharacter` resource.
///
/// ```
/// # use bevy_ecs::prelude::*;
@ -775,6 +808,10 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(print_selected_character_name_system);
/// ```
///
/// # See also
///
/// - [`get_mut`](Self::get_mut) to get a mutable query item.
#[inline]
pub fn get(&self, entity: Entity) -> Result<ROQueryItem<'_, Q>, QueryEntityError> {
// SAFETY: system runs without conflicts with other systems.
@ -789,14 +826,15 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns the read-only query results for the given array of [`Entity`].
/// Returns the read-only query items for the given array of [`Entity`].
///
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is
/// returned instead.
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is returned instead.
/// The elements of the array do not need to be unique, unlike `get_many_mut`.
///
/// Note that the unlike [`Query::get_many_mut`], the entities passed in do not need to be unique.
/// # See also
///
/// See [`Query::many`] for the infallible equivalent.
/// - [`get_many_mut`](Self::get_many_mut) to get mutable query items.
/// - [`many`](Self::many) for the panicking version.
#[inline]
pub fn get_many<const N: usize>(
&self,
@ -813,9 +851,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns the read-only query items for the provided array of [`Entity`]
/// Returns the read-only query items for the given array of [`Entity`].
///
/// See [`Query::get_many`] for the [`Result`]-returning equivalent.
/// # Panics
///
/// This method panics if there is a query mismatch or a non-existing entity.
///
/// # Examples
/// ```rust, no_run
@ -848,20 +888,22 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// }
/// ```
///
/// # See also
///
/// - [`get_many`](Self::get_many) for the non-panicking version.
#[inline]
pub fn many<const N: usize>(&self, entities: [Entity; N]) -> [ROQueryItem<'_, Q>; N] {
self.get_many(entities).unwrap()
}
/// Returns the query result for the given [`Entity`].
/// Returns the query item for the given [`Entity`].
///
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is
/// returned instead.
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is returned instead.
///
/// # Example
///
/// Here, `get_mut` is used to retrieve the exact query result of the entity specified by the
/// `PoisonedCharacter` resource.
/// Here, `get_mut` is used to retrieve the exact query item of the entity specified by the `PoisonedCharacter` resource.
///
/// ```
/// # use bevy_ecs::prelude::*;
@ -878,6 +920,10 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(poison_system);
/// ```
///
/// # See also
///
/// - [`get`](Self::get) to get a read-only query item.
#[inline]
pub fn get_mut(&mut self, entity: Entity) -> Result<QueryItem<'_, Q>, QueryEntityError> {
// SAFETY: system runs without conflicts with other systems.
@ -892,12 +938,14 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns the query results for the given array of [`Entity`].
/// Returns the query items for the given array of [`Entity`].
///
/// In case of a nonexisting entity, duplicate entities or mismatched component, a [`QueryEntityError`] is
/// returned instead.
/// In case of a nonexisting entity, duplicate entities or mismatched component, a [`QueryEntityError`] is returned instead.
///
/// See [`Query::many_mut`] for the infallible equivalent.
/// # See also
///
/// - [`get_many`](Self::get_many) to get read-only query items.
/// - [`many_mut`](Self::many_mut) for the panicking version.
#[inline]
pub fn get_many_mut<const N: usize>(
&mut self,
@ -914,9 +962,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns the query items for the provided array of [`Entity`]
/// Returns the query items for the given array of [`Entity`].
///
/// See [`Query::get_many_mut`] for the [`Result`]-returning equivalent.
/// # Panics
///
/// This method panics if there is a query mismatch, a non-existing entity, or the same `Entity` is included more than once in the array.
///
/// # Examples
///
@ -955,20 +1005,28 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// }
/// ```
///
/// # See also
///
/// - [`get_many_mut`](Self::get_many_mut) for the non panicking version.
/// - [`many`](Self::many) to get read-only query items.
#[inline]
pub fn many_mut<const N: usize>(&mut self, entities: [Entity; N]) -> [QueryItem<'_, Q>; N] {
self.get_many_mut(entities).unwrap()
}
/// Returns the query result for the given [`Entity`].
/// Returns the query item for the given [`Entity`].
///
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is
/// returned instead.
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is returned instead.
///
/// # Safety
///
/// This function makes it possible to violate Rust's aliasing guarantees. You must make sure
/// this call does not result in multiple mutable references to the same component
/// This function makes it possible to violate Rust's aliasing guarantees.
/// You must make sure this call does not result in multiple mutable references to the same component.
///
/// # See also
///
/// - [`get_mut`](Self::get_mut) for the safe version.
#[inline]
pub unsafe fn get_unchecked(
&self,
@ -980,15 +1038,13 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
.get_unchecked_manual(self.world, entity, self.last_change_tick, self.change_tick)
}
/// Returns a reference to the [`Entity`]'s [`Component`] of the given type.
/// Returns a shared reference to the component `T` of the given [`Entity`].
///
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is
/// returned instead.
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is returned instead.
///
/// # Example
///
/// Here, `get_component` is used to retrieve the `Character` component of the entity
/// specified by the `SelectedCharacter` resource.
/// Here, `get_component` is used to retrieve the `Character` component of the entity specified by the `SelectedCharacter` resource.
///
/// ```
/// # use bevy_ecs::prelude::*;
@ -1009,6 +1065,10 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(print_selected_character_name_system);
/// ```
///
/// # See also
///
/// - [`get_component_mut`](Self::get_component_mut) to get a mutable reference of a component.
#[inline]
pub fn get_component<T: Component>(&self, entity: Entity) -> Result<&T, QueryComponentError> {
let world = self.world;
@ -1036,15 +1096,13 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns a mutable reference to the [`Entity`]'s [`Component`] of the given type.
/// Returns a mutable reference to the component `T` of the given entity.
///
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is
/// returned instead.
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is returned instead.
///
/// # Example
///
/// Here, `get_component_mut` is used to retrieve the `Health` component of the entity
/// specified by the `PoisonedCharacter` resource.
/// Here, `get_component_mut` is used to retrieve the `Health` component of the entity specified by the `PoisonedCharacter` resource.
///
/// ```
/// # use bevy_ecs::prelude::*;
@ -1061,6 +1119,10 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(poison_system);
/// ```
///
/// # See also
///
/// - [`get_component`](Self::get_component) to get a shared reference of a component.
#[inline]
pub fn get_component_mut<T: Component>(
&mut self,
@ -1070,15 +1132,18 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
unsafe { self.get_component_unchecked_mut(entity) }
}
/// Returns a mutable reference to the [`Entity`]'s [`Component`] of the given type.
/// Returns a mutable reference to the component `T` of the given entity.
///
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is
/// returned instead.
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is returned instead.
///
/// # Safety
///
/// This function makes it possible to violate Rust's aliasing guarantees. You must make sure
/// this call does not result in multiple mutable references to the same component
/// This function makes it possible to violate Rust's aliasing guarantees.
/// You must make sure this call does not result in multiple mutable references to the same component.
///
/// # See also
///
/// - [`get_component_mut`](Self::get_component_mut) for the safe version.
#[inline]
pub unsafe fn get_component_unchecked_mut<T: Component>(
&self,
@ -1109,11 +1174,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns a single immutable query result when there is exactly one entity matching
/// the query.
/// Returns a single read-only query item when there is exactly one entity matching the query.
///
/// This can only return immutable data. Use [`single_mut`](Self::single_mut) for
/// queries that contain at least one mutable component.
/// # Panics
///
/// This method panics if the number of query items is **not** exactly one.
///
/// # Example
///
@ -1130,23 +1195,18 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// # bevy_ecs::system::assert_is_system(player_system);
/// ```
///
/// # Panics
/// # See also
///
/// Panics if the number of query results is not exactly one. Use
/// [`get_single`](Self::get_single) to return a `Result` instead of panicking.
/// - [`get_single`](Self::get_single) for the non-panicking version.
/// - [`single_mut`](Self::single_mut) to get the mutable query item.
#[track_caller]
pub fn single(&self) -> ROQueryItem<'_, Q> {
self.get_single().unwrap()
}
/// Returns a single immutable query result when there is exactly one entity matching
/// the query.
/// Returns a single read-only query item when there is exactly one entity matching the query.
///
/// This can only return immutable data. Use [`get_single_mut`](Self::get_single_mut)
/// for queries that contain at least one mutable component.
///
/// If the number of query results is not exactly one, a [`QuerySingleError`] is returned
/// instead.
/// If the number of query items is not exactly one, a [`QuerySingleError`] is returned instead.
///
/// # Example
///
@ -1170,6 +1230,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(player_scoring_system);
/// ```
///
/// # See also
///
/// - [`get_single_mut`](Self::get_single_mut) to get the mutable query item.
/// - [`single`](Self::single) for the panicking version.
#[inline]
pub fn get_single(&self) -> Result<ROQueryItem<'_, Q>, QuerySingleError> {
// SAFETY:
@ -1184,8 +1249,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns a single mutable query result when there is exactly one entity matching
/// the query.
/// Returns a single query item when there is exactly one entity matching the query.
///
/// # Panics
///
/// This method panics if the number of query item is **not** exactly one.
///
/// # Example
///
@ -1204,20 +1272,18 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// # bevy_ecs::system::assert_is_system(regenerate_player_health_system);
/// ```
///
/// # Panics
/// # See also
///
/// Panics if the number of query results is not exactly one. Use
/// [`get_single_mut`](Self::get_single_mut) to return a `Result` instead of panicking.
/// - [`get_single_mut`](Self::get_single_mut) for the non-panicking version.
/// - [`single`](Self::single) to get the read-only query item.
#[track_caller]
pub fn single_mut(&mut self) -> QueryItem<'_, Q> {
self.get_single_mut().unwrap()
}
/// Returns a single mutable query result when there is exactly one entity matching
/// the query.
/// Returns a single query item when there is exactly one entity matching the query.
///
/// If the number of query results is not exactly one, a [`QuerySingleError`] is returned
/// instead.
/// If the number of query items is not exactly one, a [`QuerySingleError`] is returned instead.
///
/// # Example
///
@ -1235,6 +1301,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// }
/// # bevy_ecs::system::assert_is_system(regenerate_player_health_system);
/// ```
///
/// # See also
///
/// - [`get_single`](Self::get_single) to get the read-only query item.
/// - [`single_mut`](Self::single_mut) for the panicking version.
#[inline]
pub fn get_single_mut(&mut self) -> Result<QueryItem<'_, Q>, QuerySingleError> {
// SAFETY:
@ -1249,12 +1320,11 @@ impl<'w, 's, Q: WorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns `true` if there are no query results.
/// Returns `true` if there are no query items.
///
/// # Example
///
/// Here, the score is increased only if an entity with a `Player` component is present
/// in the world:
/// Here, the score is increased only if an entity with a `Player` component is present in the world:
///
/// ```
/// # use bevy_ecs::prelude::*;
@ -1365,7 +1435,7 @@ impl std::fmt::Display for QueryComponentError {
}
impl<'w, 's, Q: ReadOnlyWorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
/// Returns the query result for the given [`Entity`], with the actual "inner" world lifetime.
/// Returns the query item for the given [`Entity`], with the actual "inner" world lifetime.
///
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is
/// returned instead.
@ -1375,7 +1445,7 @@ impl<'w, 's, Q: ReadOnlyWorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
///
/// # Example
///
/// Here, `get` is used to retrieve the exact query result of the entity specified by the
/// Here, `get` is used to retrieve the exact query item of the entity specified by the
/// `SelectedCharacter` resource.
///
/// ```
@ -1411,7 +1481,7 @@ impl<'w, 's, Q: ReadOnlyWorldQuery, F: WorldQuery> Query<'w, 's, Q, F> {
}
}
/// Returns an [`Iterator`] over the query results, with the actual "inner" world lifetime.
/// Returns an [`Iterator`] over the query items, with the actual "inner" world lifetime.
///
/// This can only return immutable data (mutable data will be cast to an immutable form).
/// See [`Self::iter_mut`] for queries that contain at least one mutable component.