mirror of
https://github.com/bevyengine/bevy
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# Objective - Adding Debug implementations for App, Stage, Schedule, Query, QueryState. - Fixes #1130. ## Solution - Implemented std::fmt::Debug for a number of structures. --- ## Changelog Also added Debug implementations for ParallelSystemExecutor, SingleThreadedExecutor, various RunCriteria structures, SystemContainer, and SystemDescriptor. Opinions are sure to differ as to what information to provide in a Debug implementation. Best guess was taken for this initial version for these structures. Co-authored-by: targrub <62773321+targrub@users.noreply.github.com>
1525 lines
54 KiB
Rust
1525 lines
54 KiB
Rust
use crate::{
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component::Component,
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entity::Entity,
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query::{
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QueryCombinationIter, QueryEntityError, QueryItem, QueryIter, QueryManyIter,
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QuerySingleError, QueryState, ROQueryItem, ReadOnlyWorldQuery, WorldQuery,
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},
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world::{Mut, World},
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};
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use std::{any::TypeId, borrow::Borrow, fmt::Debug};
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/// [System parameter] that provides selective access to the [`Component`] data stored in a [`World`].
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///
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/// Enables access to [entity identifiers] and [components] from a system, without the need to directly access the world.
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/// Its iterators and getter methods return *query items*.
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/// Each query item is a type containing data relative to an entity.
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///
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/// `Query` is a generic data structure that accepts two type parameters, both of which must implement the [`WorldQuery`] trait:
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///
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/// - **`Q` (query fetch).**
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/// The type of data contained in the query item.
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/// Only entities that match the requested data will generate an item.
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/// - **`F` (query filter).**
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/// A set of conditions that determines whether query items should be kept or discarded.
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/// This type parameter is optional.
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///
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/// # System parameter declaration
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///
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/// A query should always be declared as a system parameter.
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/// This section shows the most common idioms involving the declaration of `Query`, emerging by combining [`WorldQuery`] implementors.
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///
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/// ## Component access
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///
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/// A query defined with a reference to a component as the query fetch type parameter can be used to generate items that refer to the data of said component.
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// # #[derive(Component)]
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/// # struct ComponentA;
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/// # fn immutable_ref(
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/// // A component can be accessed by shared reference...
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/// query: Query<&ComponentA>
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/// # ) {}
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/// # bevy_ecs::system::assert_is_system(immutable_ref);
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///
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/// # fn mutable_ref(
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/// // ... or by mutable reference.
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/// query: Query<&mut ComponentA>
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/// # ) {}
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/// # bevy_ecs::system::assert_is_system(mutable_ref);
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/// ```
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///
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/// ## Query filtering
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///
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/// Setting the query filter type parameter will ensure that each query item satisfies the given condition.
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// # #[derive(Component)]
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/// # struct ComponentA;
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/// # #[derive(Component)]
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/// # struct ComponentB;
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/// # fn system(
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/// // Just `ComponentA` data will be accessed, but only for entities that also contain
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/// // `ComponentB`.
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/// query: Query<&ComponentA, With<ComponentB>>
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/// # ) {}
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/// # bevy_ecs::system::assert_is_system(system);
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/// ```
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///
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/// ## `WorldQuery` tuples
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///
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/// Using tuples, each `Query` type parameter can contain multiple elements.
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///
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/// In the following example, two components are accessed simultaneously, and the query items are filtered on two conditions.
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// # #[derive(Component)]
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/// # struct ComponentA;
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/// # #[derive(Component)]
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/// # struct ComponentB;
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/// # #[derive(Component)]
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/// # struct ComponentC;
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/// # #[derive(Component)]
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/// # struct ComponentD;
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/// # fn immutable_ref(
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/// query: Query<(&ComponentA, &ComponentB), (With<ComponentC>, Without<ComponentD>)>
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/// # ) {}
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/// # bevy_ecs::system::assert_is_system(immutable_ref);
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/// ```
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///
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/// ## Entity identifier access
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///
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/// The identifier of an entity can be made available inside the query item by including [`Entity`] in the query fetch type parameter.
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// # #[derive(Component)]
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/// # struct ComponentA;
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/// # fn system(
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/// query: Query<(Entity, &ComponentA)>
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/// # ) {}
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/// # bevy_ecs::system::assert_is_system(system);
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/// ```
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///
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/// ## Optional component access
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///
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/// A component can be made optional in a query by wrapping it into an [`Option`].
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/// In this way, a query item can still be generated even if the queried entity does not contain the wrapped component.
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/// In this case, its corresponding value will be `None`.
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// # #[derive(Component)]
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/// # struct ComponentA;
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/// # #[derive(Component)]
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/// # struct ComponentB;
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/// # fn system(
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/// // Generates items for entities that contain `ComponentA`, and optionally `ComponentB`.
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/// query: Query<(&ComponentA, Option<&ComponentB>)>
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/// # ) {}
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/// # bevy_ecs::system::assert_is_system(system);
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/// ```
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///
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/// See the documentation for [`AnyOf`] to idiomatically declare many optional components.
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///
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/// See the [performance] section to learn more about the impact of optional components.
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///
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/// ## Disjoint queries
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///
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/// A system cannot contain two queries that break Rust's mutability rules.
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/// In this case, the [`Without`] filter can be used to disjoint them.
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///
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/// In the following example, two queries mutably access the same component.
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/// Executing this system will panic, since an entity could potentially match the two queries at the same time by having both `Player` and `Enemy` components.
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/// This would violate mutability rules.
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///
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/// ```should_panic
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/// # use bevy_ecs::prelude::*;
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/// # #[derive(Component)]
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/// # struct Health;
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/// # #[derive(Component)]
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/// # struct Player;
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/// # #[derive(Component)]
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/// # struct Enemy;
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/// #
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/// fn randomize_health(
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/// player_query: Query<&mut Health, With<Player>>,
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/// enemy_query: Query<&mut Health, With<Enemy>>,
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/// )
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/// # {}
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/// # let mut randomize_health_system = bevy_ecs::system::IntoSystem::into_system(randomize_health);
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/// # let mut world = World::new();
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/// # randomize_health_system.initialize(&mut world);
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/// # randomize_health_system.run((), &mut world);
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/// ```
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///
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/// Adding a `Without` filter will disjoint the queries.
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/// In this way, any entity that has both `Player` and `Enemy` components is excluded from both queries.
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// # #[derive(Component)]
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/// # struct Health;
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/// # #[derive(Component)]
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/// # struct Player;
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/// # #[derive(Component)]
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/// # struct Enemy;
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/// #
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/// fn randomize_health(
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/// player_query: Query<&mut Health, (With<Player>, Without<Enemy>)>,
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/// enemy_query: Query<&mut Health, (With<Enemy>, Without<Player>)>,
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/// )
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/// # {}
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/// # let mut randomize_health_system = bevy_ecs::system::IntoSystem::into_system(randomize_health);
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/// # let mut world = World::new();
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/// # randomize_health_system.initialize(&mut world);
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/// # randomize_health_system.run((), &mut world);
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/// ```
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///
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/// An alternative to this idiom is to wrap the conflicting queries into a [`ParamSet`](super::ParamSet).
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///
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/// # Accessing query items
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///
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/// The following table summarizes the behavior of the safe methods that can be used to get query items.
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///
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/// |Query methods|Effect|
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/// |:---:|---|
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/// |[`iter`]\([`_mut`][`iter_mut`])|Returns an iterator over all query items.|
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/// |[`for_each`]\([`_mut`][`for_each_mut`]),<br>[`par_for_each`]\([`_mut`][`par_for_each_mut`])|Runs a specified function for each query item.|
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/// |[`iter_many`]\([`_mut`][`iter_many_mut`])|Iterates or runs a specified function over query items generated by a list of entities.|
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/// |[`iter_combinations`]\([`_mut`][`iter_combinations_mut`])|Returns an iterator over all combinations of a specified number of query items.|
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/// |[`get`]\([`_mut`][`get_mut`])|Returns the query item for the specified entity.|
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/// |[`many`]\([`_mut`][`many_mut`]),<br>[`get_many`]\([`_mut`][`get_many_mut`])|Returns the query items for the specified entities.|
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/// |[`single`]\([`_mut`][`single_mut`]),<br>[`get_single`]\([`_mut`][`get_single_mut`])|Returns the query item while verifying that there aren't others.|
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///
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/// There are two methods for each type of query operation: immutable and mutable (ending with `_mut`).
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/// When using immutable methods, the query items returned are of type [`ROQueryItem`], a read-only version of the query item.
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/// In this circumstance, every mutable reference in the query fetch type parameter is substituted by a shared reference.
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///
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/// # Performance
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///
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/// Creating a `Query` is a low-cost constant operation.
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/// Iterating it, on the other hand, fetches data from the world and generates items, which can have a significant computational cost.
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///
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/// [`Table`] component storage type is much more optimized for query iteration than [`SparseSet`].
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///
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/// Two systems cannot be executed in parallel if both access the same component type where at least one of the accesses is mutable.
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/// This happens unless the executor can verify that no entity could be found in both queries.
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///
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/// Optional components increase the number of entities a query has to match against.
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/// This can hurt iteration performance, especially if the query solely consists of only optional components, since the query would iterate over each entity in the world.
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///
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/// The following table compares the computational complexity of the various methods and operations, where:
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///
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/// - **n** is the number of entities that match the query,
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/// - **r** is the number of elements in a combination,
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/// - **k** is the number of involved entities in the operation,
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/// - **a** is the number of archetypes in the world,
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/// - **C** is the [binomial coefficient], used to count combinations.
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/// <sub>n</sub>C<sub>r</sub> is read as "*n* choose *r*" and is equivalent to the number of distinct unordered subsets of *r* elements that can be taken from a set of *n* elements.
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///
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/// |Query operation|Computational complexity|
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/// |:---:|:---:|
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/// |[`iter`]\([`_mut`][`iter_mut`])|O(n)|
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/// |[`for_each`]\([`_mut`][`for_each_mut`]),<br>[`par_for_each`]\([`_mut`][`par_for_each_mut`])|O(n)|
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/// |[`iter_many`]\([`_mut`][`iter_many_mut`])|O(k)|
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/// |[`iter_combinations`]\([`_mut`][`iter_combinations_mut`])|O(<sub>n</sub>C<sub>r</sub>)|
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/// |[`get`]\([`_mut`][`get_mut`])|O(1)|
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/// |([`get_`][`get_many`])[`many`]|O(k)|
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/// |([`get_`][`get_many_mut`])[`many_mut`]|O(k<sup>2</sup>)|
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/// |[`single`]\([`_mut`][`single_mut`]),<br>[`get_single`]\([`_mut`][`get_single_mut`])|O(a)|
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/// |Archetype based filtering ([`With`], [`Without`], [`Or`])|O(a)|
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/// |Change detection filtering ([`Added`], [`Changed`])|O(a + n)|
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///
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/// `for_each` methods are seen to be generally faster than their `iter` version on worlds with high archetype fragmentation.
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/// As iterators are in general more flexible and better integrated with the rest of the Rust ecosystem,
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/// it is advised to use `iter` methods over `for_each`.
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/// It is strongly advised to only use `for_each` if it tangibly improves performance:
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/// be sure profile or benchmark both before and after the change.
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///
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/// [`Added`]: crate::query::Added
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/// [`AnyOf`]: crate::query::AnyOf
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/// [binomial coefficient]: https://en.wikipedia.org/wiki/Binomial_coefficient
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/// [`Changed`]: crate::query::Changed
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/// [components]: crate::component::Component
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/// [entity identifiers]: crate::entity::Entity
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/// [`for_each`]: Self::for_each
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/// [`for_each_mut`]: Self::for_each_mut
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/// [`get`]: Self::get
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/// [`get_many`]: Self::get_many
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/// [`get_many_mut`]: Self::get_many_mut
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/// [`get_mut`]: Self::get_mut
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/// [`get_single`]: Self::get_single
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/// [`get_single_mut`]: Self::get_single_mut
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/// [`iter`]: Self::iter
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/// [`iter_combinations`]: Self::iter_combinations
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/// [`iter_combinations_mut`]: Self::iter_combinations_mut
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/// [`iter_many`]: Self::iter_many
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/// [`iter_many_mut`]: Self::iter_many_mut
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/// [`iter_mut`]: Self::iter_mut
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/// [`many`]: Self::many
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/// [`many_mut`]: Self::many_mut
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/// [`Or`]: crate::query::Or
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/// [`par_for_each`]: Self::par_for_each
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/// [`par_for_each_mut`]: Self::par_for_each_mut
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/// [performance]: #performance
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/// [`single`]: Self::single
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/// [`single_mut`]: Self::single_mut
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/// [`SparseSet`]: crate::storage::SparseSet
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/// [System parameter]: crate::system::SystemParam
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/// [`Table`]: crate::storage::Table
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/// [`With`]: crate::query::With
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/// [`Without`]: crate::query::Without
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pub struct Query<'world, 'state, Q: WorldQuery, F: ReadOnlyWorldQuery = ()> {
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pub(crate) world: &'world World,
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pub(crate) state: &'state QueryState<Q, F>,
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pub(crate) last_change_tick: u32,
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pub(crate) change_tick: u32,
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}
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impl<'w, 's, Q: WorldQuery, F: ReadOnlyWorldQuery> std::fmt::Debug for Query<'w, 's, Q, F> {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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write!(f, "Query {{ matched entities: {}, world: {:?}, state: {:?}, last_change_tick: {}, change_tick: {} }}", self.iter().count(), self.world, self.state, self.last_change_tick, self.change_tick)
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}
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}
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impl<'w, 's, Q: WorldQuery, F: ReadOnlyWorldQuery> Query<'w, 's, Q, F> {
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/// Creates a new query.
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///
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/// # Safety
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///
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/// This will create a query that could violate memory safety rules. Make sure that this is only
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/// called in ways that ensure the queries have unique mutable access.
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#[inline]
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pub(crate) unsafe fn new(
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world: &'w World,
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state: &'s QueryState<Q, F>,
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last_change_tick: u32,
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change_tick: u32,
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) -> Self {
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Self {
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world,
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state,
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last_change_tick,
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change_tick,
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}
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}
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/// Returns another `Query` from this that fetches the read-only version of the query items.
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///
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/// For example, `Query<(&mut A, &B, &mut C), With<D>>` will become `Query<(&A, &B, &C), With<D>>`.
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/// This can be useful when working around the borrow checker,
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/// or reusing functionality between systems via functions that accept query types.
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pub fn to_readonly(&self) -> Query<'_, 's, Q::ReadOnly, F::ReadOnly> {
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let new_state = self.state.as_readonly();
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// SAFETY: This is memory safe because it turns the query immutable.
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unsafe {
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Query::new(
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self.world,
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new_state,
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self.last_change_tick,
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self.change_tick,
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)
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}
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}
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/// Returns an [`Iterator`] over the read-only query items.
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///
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/// # Example
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///
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/// Here, the `report_names_system` iterates over the `Player` component of every entity that contains it:
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// #
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/// # #[derive(Component)]
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/// # struct Player { name: String }
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/// #
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/// fn report_names_system(query: Query<&Player>) {
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/// for player in &query {
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/// println!("Say hello to {}!", player.name);
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/// }
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/// }
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/// # bevy_ecs::system::assert_is_system(report_names_system);
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/// ```
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///
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/// # See also
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///
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/// - [`iter_mut`](Self::iter_mut) for mutable query items.
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/// - [`for_each`](Self::for_each) for the closure based alternative.
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#[inline]
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pub fn iter(&self) -> QueryIter<'_, 's, Q::ReadOnly, F::ReadOnly> {
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// SAFETY: system runs without conflicts with other systems.
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// same-system queries have runtime borrow checks when they conflict
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unsafe {
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self.state.as_readonly().iter_unchecked_manual(
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self.world,
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self.last_change_tick,
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self.change_tick,
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)
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}
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}
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/// Returns an [`Iterator`] over the query items.
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///
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/// # Example
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///
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/// Here, the `gravity_system` updates the `Velocity` component of every entity that contains it:
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// #
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/// # #[derive(Component)]
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/// # struct Velocity { x: f32, y: f32, z: f32 }
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/// fn gravity_system(mut query: Query<&mut Velocity>) {
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/// const DELTA: f32 = 1.0 / 60.0;
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/// for mut velocity in &mut query {
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/// velocity.y -= 9.8 * DELTA;
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/// }
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/// }
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/// # bevy_ecs::system::assert_is_system(gravity_system);
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/// ```
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///
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/// # See also
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///
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/// - [`iter`](Self::iter) for read-only query items.
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/// - [`for_each_mut`](Self::for_each_mut) for the closure based alternative.
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#[inline]
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pub fn iter_mut(&mut self) -> QueryIter<'_, 's, Q, F> {
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// SAFETY: system runs without conflicts with other systems.
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// same-system queries have runtime borrow checks when they conflict
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unsafe {
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self.state
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.iter_unchecked_manual(self.world, self.last_change_tick, self.change_tick)
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}
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}
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/// Returns a [`QueryCombinationIter`] over all combinations of `K` read-only query items without repetition.
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///
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/// # Example
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// # #[derive(Component)]
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/// # struct ComponentA;
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/// #
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/// fn some_system(query: Query<&ComponentA>) {
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/// for [a1, a2] in query.iter_combinations() {
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/// // ...
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/// }
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/// }
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/// ```
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///
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/// # See also
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///
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/// - [`iter_combinations_mut`](Self::iter_combinations_mut) for mutable query item combinations.
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#[inline]
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pub fn iter_combinations<const K: usize>(
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&self,
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) -> QueryCombinationIter<'_, 's, Q::ReadOnly, F::ReadOnly, K> {
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// SAFETY: system runs without conflicts with other systems.
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|
// same-system queries have runtime borrow checks when they conflict
|
|
unsafe {
|
|
self.state.as_readonly().iter_combinations_unchecked_manual(
|
|
self.world,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// Returns a [`QueryCombinationIter`] over all combinations of `K` query items without repetition.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// # #[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
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// # See also
|
|
///
|
|
/// - [`iter_combinations`](Self::iter_combinations) for read-only query item combinations.
|
|
#[inline]
|
|
pub fn iter_combinations_mut<const K: usize>(
|
|
&mut self,
|
|
) -> QueryCombinationIter<'_, 's, Q, F, K> {
|
|
// SAFETY: system runs without conflicts with other systems.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
unsafe {
|
|
self.state.iter_combinations_unchecked_manual(
|
|
self.world,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// Returns an [`Iterator`] over the read-only query items generated from an [`Entity`] list.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// # #[derive(Component)]
|
|
/// # struct Counter {
|
|
/// # value: i32
|
|
/// # }
|
|
/// #
|
|
/// // A component containing an entity list.
|
|
/// #[derive(Component)]
|
|
/// struct Friends {
|
|
/// list: Vec<Entity>,
|
|
/// }
|
|
///
|
|
/// fn system(
|
|
/// friends_query: Query<&Friends>,
|
|
/// counter_query: Query<&Counter>,
|
|
/// ) {
|
|
/// for friends in &friends_query {
|
|
/// for counter in counter_query.iter_many(&friends.list) {
|
|
/// println!("Friend's counter: {:?}", counter.value);
|
|
/// }
|
|
/// }
|
|
/// }
|
|
/// # 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,
|
|
entities: EntityList,
|
|
) -> QueryManyIter<'_, 's, Q::ReadOnly, F::ReadOnly, EntityList::IntoIter>
|
|
where
|
|
EntityList::Item: Borrow<Entity>,
|
|
{
|
|
// SAFETY: system runs without conflicts with other systems.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
unsafe {
|
|
self.state.as_readonly().iter_many_unchecked_manual(
|
|
entities,
|
|
self.world,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// Returns an [`Iterator`] over the query items generated from an [`Entity`] list.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #[derive(Component)]
|
|
/// struct Counter {
|
|
/// value: i32
|
|
/// }
|
|
///
|
|
/// #[derive(Component)]
|
|
/// struct Friends {
|
|
/// list: Vec<Entity>,
|
|
/// }
|
|
///
|
|
/// fn system(
|
|
/// friends_query: Query<&Friends>,
|
|
/// mut counter_query: Query<&mut Counter>,
|
|
/// ) {
|
|
/// for friends in &friends_query {
|
|
/// let mut iter = counter_query.iter_many_mut(&friends.list);
|
|
/// while let Some(mut counter) = iter.fetch_next() {
|
|
/// println!("Friend's counter: {:?}", counter.value);
|
|
/// counter.value += 1;
|
|
/// }
|
|
/// }
|
|
/// }
|
|
/// # bevy_ecs::system::assert_is_system(system);
|
|
/// ```
|
|
#[inline]
|
|
pub fn iter_many_mut<EntityList: IntoIterator>(
|
|
&mut self,
|
|
entities: EntityList,
|
|
) -> QueryManyIter<'_, 's, Q, F, EntityList::IntoIter>
|
|
where
|
|
EntityList::Item: Borrow<Entity>,
|
|
{
|
|
// SAFETY: system runs without conflicts with other systems.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
unsafe {
|
|
self.state.iter_many_unchecked_manual(
|
|
entities,
|
|
self.world,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// 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.
|
|
///
|
|
/// # 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.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
self.state
|
|
.iter_unchecked_manual(self.world, self.last_change_tick, self.change_tick)
|
|
}
|
|
|
|
/// 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.
|
|
///
|
|
/// # 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,
|
|
) -> QueryCombinationIter<'_, 's, Q, F, K> {
|
|
// SEMI-SAFETY: system runs without conflicts with other systems.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
self.state.iter_combinations_unchecked_manual(
|
|
self.world,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
|
|
/// 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`].
|
|
///
|
|
/// # 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,
|
|
) -> QueryManyIter<'_, 's, Q, F, EntityList::IntoIter>
|
|
where
|
|
EntityList::Item: Borrow<Entity>,
|
|
{
|
|
self.state.iter_many_unchecked_manual(
|
|
entities,
|
|
self.world,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
|
|
/// 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:
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Component)]
|
|
/// # struct Player { name: String }
|
|
/// #
|
|
/// fn report_names_system(query: Query<&Player>) {
|
|
/// query.for_each(|player| {
|
|
/// println!("Say hello to {}!", player.name);
|
|
/// });
|
|
/// }
|
|
/// # 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.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
unsafe {
|
|
self.state.as_readonly().for_each_unchecked_manual(
|
|
self.world,
|
|
f,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
);
|
|
};
|
|
}
|
|
|
|
/// Runs `f` on each query item.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// Here, the `gravity_system` updates the `Velocity` component of every entity that contains it:
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Component)]
|
|
/// # struct Velocity { x: f32, y: f32, z: f32 }
|
|
/// fn gravity_system(mut query: Query<&mut Velocity>) {
|
|
/// const DELTA: f32 = 1.0 / 60.0;
|
|
/// query.for_each_mut(|mut velocity| {
|
|
/// velocity.y -= 9.8 * DELTA;
|
|
/// });
|
|
/// }
|
|
/// # 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
|
|
// borrow checks when they conflict
|
|
unsafe {
|
|
self.state.for_each_unchecked_manual(
|
|
self.world,
|
|
f,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
);
|
|
};
|
|
}
|
|
|
|
/// Runs `f` on each read-only query item in parallel.
|
|
///
|
|
/// Parallelization is achieved by using the [`World`]'s [`ComputeTaskPool`].
|
|
///
|
|
/// # Tasks and batch size
|
|
///
|
|
/// The items in the query get sorted into batches.
|
|
/// Internally, this function spawns a group of futures that each take on a `batch_size` sized section of the items (or less if the division is not perfect).
|
|
/// Then, the tasks in the [`ComputeTaskPool`] work through these futures.
|
|
///
|
|
/// You can use this value to tune between maximum multithreading ability (many small batches) and minimum parallelization overhead (few big batches).
|
|
/// 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.
|
|
///
|
|
/// [`ComputeTaskPool`]: bevy_tasks::prelude::ComputeTaskPool
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// 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,
|
|
batch_size: usize,
|
|
f: impl Fn(ROQueryItem<'this, Q>) + Send + Sync + Clone,
|
|
) {
|
|
// SAFETY: system runs without conflicts with other systems. same-system queries have runtime
|
|
// borrow checks when they conflict
|
|
unsafe {
|
|
self.state.as_readonly().par_for_each_unchecked_manual(
|
|
self.world,
|
|
batch_size,
|
|
f,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
);
|
|
};
|
|
}
|
|
|
|
/// Runs `f` on each read-only query item in parallel.
|
|
///
|
|
/// Parallelization is achieved by using the [`World`]'s [`ComputeTaskPool`].
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// 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,
|
|
batch_size: usize,
|
|
f: impl Fn(QueryItem<'a, Q>) + Send + Sync + Clone,
|
|
) {
|
|
// SAFETY: system runs without conflicts with other systems. same-system queries have runtime
|
|
// borrow checks when they conflict
|
|
unsafe {
|
|
self.state.par_for_each_unchecked_manual(
|
|
self.world,
|
|
batch_size,
|
|
f,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
);
|
|
};
|
|
}
|
|
|
|
/// Returns the read-only query item for the given [`Entity`].
|
|
///
|
|
/// In case of a nonexisting entity or mismatched component, a [`QueryEntityError`] is returned instead.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// Here, `get` is used to retrieve the exact query item of the entity specified by the `SelectedCharacter` resource.
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Resource)]
|
|
/// # struct SelectedCharacter { entity: Entity }
|
|
/// # #[derive(Component)]
|
|
/// # struct Character { name: String }
|
|
/// #
|
|
/// fn print_selected_character_name_system(
|
|
/// query: Query<&Character>,
|
|
/// selection: Res<SelectedCharacter>
|
|
/// )
|
|
/// {
|
|
/// if let Ok(selected_character) = query.get(selection.entity) {
|
|
/// println!("{}", selected_character.name);
|
|
/// }
|
|
/// }
|
|
/// # 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.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
unsafe {
|
|
self.state.as_readonly().get_unchecked_manual(
|
|
self.world,
|
|
entity,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// 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.
|
|
/// The elements of the array do not need to be unique, unlike `get_many_mut`.
|
|
///
|
|
/// # See also
|
|
///
|
|
/// - [`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,
|
|
entities: [Entity; N],
|
|
) -> Result<[ROQueryItem<'_, Q>; N], QueryEntityError> {
|
|
// SAFETY: it is the scheduler's responsibility to ensure that `Query` is never handed out on the wrong `World`.
|
|
unsafe {
|
|
self.state.get_many_read_only_manual(
|
|
self.world,
|
|
entities,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// Returns the read-only query items for the given array of [`Entity`].
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// This method panics if there is a query mismatch or a non-existing entity.
|
|
///
|
|
/// # Examples
|
|
/// ```rust, no_run
|
|
/// use bevy_ecs::prelude::*;
|
|
///
|
|
/// #[derive(Component)]
|
|
/// struct Targets([Entity; 3]);
|
|
///
|
|
/// #[derive(Component)]
|
|
/// struct Position{
|
|
/// x: i8,
|
|
/// y: i8
|
|
/// };
|
|
///
|
|
/// impl Position {
|
|
/// fn distance(&self, other: &Position) -> i8 {
|
|
/// // Manhattan distance is way easier to compute!
|
|
/// (self.x - other.x).abs() + (self.y - other.y).abs()
|
|
/// }
|
|
/// }
|
|
///
|
|
/// fn check_all_targets_in_range(targeting_query: Query<(Entity, &Targets, &Position)>, targets_query: Query<&Position>){
|
|
/// for (targeting_entity, targets, origin) in &targeting_query {
|
|
/// // We can use "destructuring" to unpack the results nicely
|
|
/// let [target_1, target_2, target_3] = targets_query.many(targets.0);
|
|
///
|
|
/// assert!(target_1.distance(origin) <= 5);
|
|
/// assert!(target_2.distance(origin) <= 5);
|
|
/// assert!(target_3.distance(origin) <= 5);
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// # 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 item for the given [`Entity`].
|
|
///
|
|
/// 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 item of the entity specified by the `PoisonedCharacter` resource.
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Resource)]
|
|
/// # struct PoisonedCharacter { character_id: Entity }
|
|
/// # #[derive(Component)]
|
|
/// # struct Health(u32);
|
|
/// #
|
|
/// fn poison_system(mut query: Query<&mut Health>, poisoned: Res<PoisonedCharacter>) {
|
|
/// if let Ok(mut health) = query.get_mut(poisoned.character_id) {
|
|
/// health.0 -= 1;
|
|
/// }
|
|
/// }
|
|
/// # 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.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
unsafe {
|
|
self.state.get_unchecked_manual(
|
|
self.world,
|
|
entity,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// 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.
|
|
///
|
|
/// # 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,
|
|
entities: [Entity; N],
|
|
) -> Result<[QueryItem<'_, Q>; N], QueryEntityError> {
|
|
// SAFETY: scheduler ensures safe Query world access
|
|
unsafe {
|
|
self.state.get_many_unchecked_manual(
|
|
self.world,
|
|
entities,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// Returns the query items for the given array of [`Entity`].
|
|
///
|
|
/// # 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
|
|
///
|
|
/// ```rust, no_run
|
|
/// use bevy_ecs::prelude::*;
|
|
///
|
|
/// #[derive(Component)]
|
|
/// struct Spring{
|
|
/// connected_entities: [Entity; 2],
|
|
/// strength: f32,
|
|
/// }
|
|
///
|
|
/// #[derive(Component)]
|
|
/// struct Position {
|
|
/// x: f32,
|
|
/// y: f32,
|
|
/// }
|
|
///
|
|
/// #[derive(Component)]
|
|
/// struct Force {
|
|
/// x: f32,
|
|
/// y: f32,
|
|
/// }
|
|
///
|
|
/// fn spring_forces(spring_query: Query<&Spring>, mut mass_query: Query<(&Position, &mut Force)>){
|
|
/// for spring in &spring_query {
|
|
/// // We can use "destructuring" to unpack our query items nicely
|
|
/// let [(position_1, mut force_1), (position_2, mut force_2)] = mass_query.many_mut(spring.connected_entities);
|
|
///
|
|
/// force_1.x += spring.strength * (position_1.x - position_2.x);
|
|
/// force_1.y += spring.strength * (position_1.y - position_2.y);
|
|
///
|
|
/// // Silence borrow-checker: I have split your mutable borrow!
|
|
/// force_2.x += spring.strength * (position_2.x - position_1.x);
|
|
/// force_2.y += spring.strength * (position_2.y - position_1.y);
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// # 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 item for the given [`Entity`].
|
|
///
|
|
/// 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.
|
|
///
|
|
/// # See also
|
|
///
|
|
/// - [`get_mut`](Self::get_mut) for the safe version.
|
|
#[inline]
|
|
pub unsafe fn get_unchecked(
|
|
&self,
|
|
entity: Entity,
|
|
) -> Result<QueryItem<'_, Q>, QueryEntityError> {
|
|
// SEMI-SAFETY: system runs without conflicts with other systems.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
self.state
|
|
.get_unchecked_manual(self.world, entity, self.last_change_tick, self.change_tick)
|
|
}
|
|
|
|
/// 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.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// Here, `get_component` is used to retrieve the `Character` component of the entity specified by the `SelectedCharacter` resource.
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Resource)]
|
|
/// # struct SelectedCharacter { entity: Entity }
|
|
/// # #[derive(Component)]
|
|
/// # struct Character { name: String }
|
|
/// #
|
|
/// fn print_selected_character_name_system(
|
|
/// query: Query<&Character>,
|
|
/// selection: Res<SelectedCharacter>
|
|
/// )
|
|
/// {
|
|
/// if let Ok(selected_character) = query.get_component::<Character>(selection.entity) {
|
|
/// println!("{}", selected_character.name);
|
|
/// }
|
|
/// }
|
|
/// # 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;
|
|
let entity_ref = world
|
|
.get_entity(entity)
|
|
.ok_or(QueryComponentError::NoSuchEntity)?;
|
|
let component_id = world
|
|
.components()
|
|
.get_id(TypeId::of::<T>())
|
|
.ok_or(QueryComponentError::MissingComponent)?;
|
|
let archetype_component = entity_ref
|
|
.archetype()
|
|
.get_archetype_component_id(component_id)
|
|
.ok_or(QueryComponentError::MissingComponent)?;
|
|
if self
|
|
.state
|
|
.archetype_component_access
|
|
.has_read(archetype_component)
|
|
{
|
|
entity_ref
|
|
.get::<T>()
|
|
.ok_or(QueryComponentError::MissingComponent)
|
|
} else {
|
|
Err(QueryComponentError::MissingReadAccess)
|
|
}
|
|
}
|
|
|
|
/// 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.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// Here, `get_component_mut` is used to retrieve the `Health` component of the entity specified by the `PoisonedCharacter` resource.
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Resource)]
|
|
/// # struct PoisonedCharacter { character_id: Entity }
|
|
/// # #[derive(Component)]
|
|
/// # struct Health(u32);
|
|
/// #
|
|
/// fn poison_system(mut query: Query<&mut Health>, poisoned: Res<PoisonedCharacter>) {
|
|
/// if let Ok(mut health) = query.get_component_mut::<Health>(poisoned.character_id) {
|
|
/// health.0 -= 1;
|
|
/// }
|
|
/// }
|
|
/// # 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,
|
|
entity: Entity,
|
|
) -> Result<Mut<'_, T>, QueryComponentError> {
|
|
// SAFETY: unique access to query (preventing aliased access)
|
|
unsafe { self.get_component_unchecked_mut(entity) }
|
|
}
|
|
|
|
/// 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.
|
|
///
|
|
/// # 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.
|
|
///
|
|
/// # See also
|
|
///
|
|
/// - [`get_component_mut`](Self::get_component_mut) for the safe version.
|
|
#[inline]
|
|
pub unsafe fn get_component_unchecked_mut<T: Component>(
|
|
&self,
|
|
entity: Entity,
|
|
) -> Result<Mut<'_, T>, QueryComponentError> {
|
|
let world = self.world;
|
|
let entity_ref = world
|
|
.get_entity(entity)
|
|
.ok_or(QueryComponentError::NoSuchEntity)?;
|
|
let component_id = world
|
|
.components()
|
|
.get_id(TypeId::of::<T>())
|
|
.ok_or(QueryComponentError::MissingComponent)?;
|
|
let archetype_component = entity_ref
|
|
.archetype()
|
|
.get_archetype_component_id(component_id)
|
|
.ok_or(QueryComponentError::MissingComponent)?;
|
|
if self
|
|
.state
|
|
.archetype_component_access
|
|
.has_write(archetype_component)
|
|
{
|
|
entity_ref
|
|
.get_unchecked_mut::<T>(self.last_change_tick, self.change_tick)
|
|
.ok_or(QueryComponentError::MissingComponent)
|
|
} else {
|
|
Err(QueryComponentError::MissingWriteAccess)
|
|
}
|
|
}
|
|
|
|
/// Returns a single read-only query item when there is exactly one entity matching the query.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// This method panics if the number of query items is **not** exactly one.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// # #[derive(Component)]
|
|
/// # struct Player;
|
|
/// # #[derive(Component)]
|
|
/// # struct Position(f32, f32);
|
|
/// fn player_system(query: Query<&Position, With<Player>>) {
|
|
/// let player_position = query.single();
|
|
/// // do something with player_position
|
|
/// }
|
|
/// # bevy_ecs::system::assert_is_system(player_system);
|
|
/// ```
|
|
///
|
|
/// # See also
|
|
///
|
|
/// - [`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 read-only query item when there is exactly one entity matching the query.
|
|
///
|
|
/// If the number of query items is not exactly one, a [`QuerySingleError`] is returned instead.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// # use bevy_ecs::query::QuerySingleError;
|
|
/// # #[derive(Component)]
|
|
/// # struct PlayerScore(i32);
|
|
/// fn player_scoring_system(query: Query<&PlayerScore>) {
|
|
/// match query.get_single() {
|
|
/// Ok(PlayerScore(score)) => {
|
|
/// println!("Score: {}", score);
|
|
/// }
|
|
/// Err(QuerySingleError::NoEntities(_)) => {
|
|
/// println!("Error: There is no player!");
|
|
/// }
|
|
/// Err(QuerySingleError::MultipleEntities(_)) => {
|
|
/// println!("Error: There is more than one player!");
|
|
/// }
|
|
/// }
|
|
/// }
|
|
/// # 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:
|
|
// the query ensures that the components it accesses are not mutably accessible somewhere else
|
|
// and the query is read only.
|
|
unsafe {
|
|
self.state.as_readonly().get_single_unchecked_manual(
|
|
self.world,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// 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
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Component)]
|
|
/// # struct Player;
|
|
/// # #[derive(Component)]
|
|
/// # struct Health(u32);
|
|
/// #
|
|
/// fn regenerate_player_health_system(mut query: Query<&mut Health, With<Player>>) {
|
|
/// let mut health = query.single_mut();
|
|
/// health.0 += 1;
|
|
/// }
|
|
/// # bevy_ecs::system::assert_is_system(regenerate_player_health_system);
|
|
/// ```
|
|
///
|
|
/// # See also
|
|
///
|
|
/// - [`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 query item when there is exactly one entity matching the query.
|
|
///
|
|
/// If the number of query items is not exactly one, a [`QuerySingleError`] is returned instead.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Component)]
|
|
/// # struct Player;
|
|
/// # #[derive(Component)]
|
|
/// # struct Health(u32);
|
|
/// #
|
|
/// fn regenerate_player_health_system(mut query: Query<&mut Health, With<Player>>) {
|
|
/// let mut health = query.get_single_mut().expect("Error: Could not find a single player.");
|
|
/// health.0 += 1;
|
|
/// }
|
|
/// # 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:
|
|
// the query ensures mutable access to the components it accesses, and the query
|
|
// is uniquely borrowed
|
|
unsafe {
|
|
self.state.get_single_unchecked_manual(
|
|
self.world,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// 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:
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Component)]
|
|
/// # struct Player;
|
|
/// # #[derive(Resource)]
|
|
/// # struct Score(u32);
|
|
/// fn update_score_system(query: Query<(), With<Player>>, mut score: ResMut<Score>) {
|
|
/// if !query.is_empty() {
|
|
/// score.0 += 1;
|
|
/// }
|
|
/// }
|
|
/// # bevy_ecs::system::assert_is_system(update_score_system);
|
|
/// ```
|
|
#[inline]
|
|
pub fn is_empty(&self) -> bool {
|
|
self.state
|
|
.is_empty(self.world, self.last_change_tick, self.change_tick)
|
|
}
|
|
|
|
/// Returns `true` if the given [`Entity`] matches the query.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Component)]
|
|
/// # struct InRange;
|
|
/// #
|
|
/// # #[derive(Resource)]
|
|
/// # struct Target {
|
|
/// # entity: Entity,
|
|
/// # }
|
|
/// #
|
|
/// fn targeting_system(in_range_query: Query<&InRange>, target: Res<Target>) {
|
|
/// if in_range_query.contains(target.entity) {
|
|
/// println!("Bam!")
|
|
/// }
|
|
/// }
|
|
/// # bevy_ecs::system::assert_is_system(targeting_system);
|
|
/// ```
|
|
#[inline]
|
|
pub fn contains(&self, entity: Entity) -> bool {
|
|
// SAFETY: NopFetch does not access any members while &self ensures no one has exclusive access
|
|
unsafe {
|
|
self.state
|
|
.as_nop()
|
|
.get_unchecked_manual(self.world, entity, self.last_change_tick, self.change_tick)
|
|
.is_ok()
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'w, 's, Q: WorldQuery, F: ReadOnlyWorldQuery> IntoIterator for &'w Query<'_, 's, Q, F> {
|
|
type Item = ROQueryItem<'w, Q>;
|
|
type IntoIter = QueryIter<'w, 's, Q::ReadOnly, F::ReadOnly>;
|
|
|
|
fn into_iter(self) -> Self::IntoIter {
|
|
self.iter()
|
|
}
|
|
}
|
|
|
|
impl<'w, 's, Q: WorldQuery, F: ReadOnlyWorldQuery> IntoIterator for &'w mut Query<'_, 's, Q, F> {
|
|
type Item = QueryItem<'w, Q>;
|
|
type IntoIter = QueryIter<'w, 's, Q, F>;
|
|
|
|
fn into_iter(self) -> Self::IntoIter {
|
|
self.iter_mut()
|
|
}
|
|
}
|
|
|
|
/// An error that occurs when retrieving a specific [`Entity`]'s component from a [`Query`]
|
|
#[derive(Debug)]
|
|
pub enum QueryComponentError {
|
|
MissingReadAccess,
|
|
MissingWriteAccess,
|
|
MissingComponent,
|
|
NoSuchEntity,
|
|
}
|
|
|
|
impl std::error::Error for QueryComponentError {}
|
|
|
|
impl std::fmt::Display for QueryComponentError {
|
|
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
|
|
match self {
|
|
QueryComponentError::MissingReadAccess => {
|
|
write!(
|
|
f,
|
|
"This query does not have read access to the requested component."
|
|
)
|
|
}
|
|
QueryComponentError::MissingWriteAccess => {
|
|
write!(
|
|
f,
|
|
"This query does not have write access to the requested component."
|
|
)
|
|
}
|
|
QueryComponentError::MissingComponent => {
|
|
write!(f, "The given entity does not have the requested component.")
|
|
}
|
|
QueryComponentError::NoSuchEntity => {
|
|
write!(f, "The requested entity does not exist.")
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'w, 's, Q: ReadOnlyWorldQuery, F: ReadOnlyWorldQuery> Query<'w, 's, Q, F> {
|
|
/// 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.
|
|
///
|
|
/// 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.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// Here, `get` is used to retrieve the exact query item of the entity specified by the
|
|
/// `SelectedCharacter` resource.
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Resource)]
|
|
/// # struct SelectedCharacter { entity: Entity }
|
|
/// # #[derive(Component)]
|
|
/// # struct Character { name: String }
|
|
/// #
|
|
/// fn print_selected_character_name_system(
|
|
/// query: Query<&Character>,
|
|
/// selection: Res<SelectedCharacter>
|
|
/// )
|
|
/// {
|
|
/// if let Ok(selected_character) = query.get(selection.entity) {
|
|
/// println!("{}", selected_character.name);
|
|
/// }
|
|
/// }
|
|
/// # bevy_ecs::system::assert_is_system(print_selected_character_name_system);
|
|
/// ```
|
|
#[inline]
|
|
pub fn get_inner(&self, entity: Entity) -> Result<ROQueryItem<'w, Q>, QueryEntityError> {
|
|
// SAFETY: system runs without conflicts with other systems.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
unsafe {
|
|
self.state.as_readonly().get_unchecked_manual(
|
|
self.world,
|
|
entity,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
|
|
/// 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.
|
|
///
|
|
/// # Example
|
|
///
|
|
/// Here, the `report_names_system` iterates over the `Player` component of every entity
|
|
/// that contains it:
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::prelude::*;
|
|
/// #
|
|
/// # #[derive(Component)]
|
|
/// # struct Player { name: String }
|
|
/// #
|
|
/// fn report_names_system(query: Query<&Player>) {
|
|
/// for player in &query {
|
|
/// println!("Say hello to {}!", player.name);
|
|
/// }
|
|
/// }
|
|
/// # bevy_ecs::system::assert_is_system(report_names_system);
|
|
/// ```
|
|
#[inline]
|
|
pub fn iter_inner(&self) -> QueryIter<'w, 's, Q::ReadOnly, F::ReadOnly> {
|
|
// SAFETY: system runs without conflicts with other systems.
|
|
// same-system queries have runtime borrow checks when they conflict
|
|
unsafe {
|
|
self.state.as_readonly().iter_unchecked_manual(
|
|
self.world,
|
|
self.last_change_tick,
|
|
self.change_tick,
|
|
)
|
|
}
|
|
}
|
|
}
|