1837 lines
68 KiB
Rust
1837 lines
68 KiB
Rust
//! Types for declaring and storing [`Component`]s.
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use crate::{
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self as bevy_ecs,
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archetype::ArchetypeFlags,
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bundle::BundleInfo,
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change_detection::MAX_CHANGE_AGE,
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entity::Entity,
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query::DebugCheckedUnwrap,
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storage::{SparseSetIndex, SparseSets, Storages, Table, TableRow},
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system::{Local, Resource, SystemParam},
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world::{DeferredWorld, FromWorld, World},
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};
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use alloc::{borrow::Cow, sync::Arc};
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pub use bevy_ecs_macros::Component;
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use bevy_ptr::{OwningPtr, UnsafeCellDeref};
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#[cfg(feature = "bevy_reflect")]
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use bevy_reflect::Reflect;
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use bevy_utils::{HashMap, HashSet, TypeIdMap};
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#[cfg(feature = "track_change_detection")]
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use core::panic::Location;
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use core::{
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alloc::Layout,
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any::{Any, TypeId},
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cell::UnsafeCell,
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fmt::Debug,
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marker::PhantomData,
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mem::needs_drop,
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};
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use derive_more::derive::{Display, Error};
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/// A data type that can be used to store data for an [entity].
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///
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/// `Component` is a [derivable trait]: this means that a data type can implement it by applying a `#[derive(Component)]` attribute to it.
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/// However, components must always satisfy the `Send + Sync + 'static` trait bounds.
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///
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/// [entity]: crate::entity
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/// [derivable trait]: https://doc.rust-lang.org/book/appendix-03-derivable-traits.html
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///
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/// # Examples
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///
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/// Components can take many forms: they are usually structs, but can also be of every other kind of data type, like enums or zero sized types.
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/// The following examples show how components are laid out in code.
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///
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/// ```
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/// # use bevy_ecs::component::Component;
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/// # struct Color;
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/// #
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/// // A component can contain data...
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/// #[derive(Component)]
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/// struct LicensePlate(String);
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///
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/// // ... but it can also be a zero-sized marker.
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/// #[derive(Component)]
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/// struct Car;
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///
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/// // Components can also be structs with named fields...
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/// #[derive(Component)]
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/// struct VehiclePerformance {
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/// acceleration: f32,
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/// top_speed: f32,
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/// handling: f32,
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/// }
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///
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/// // ... or enums.
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/// #[derive(Component)]
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/// enum WheelCount {
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/// Two,
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/// Three,
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/// Four,
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/// }
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/// ```
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///
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/// # Component and data access
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///
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/// See the [`entity`] module level documentation to learn how to add or remove components from an entity.
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///
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/// See the documentation for [`Query`] to learn how to access component data from a system.
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///
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/// [`entity`]: crate::entity#usage
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/// [`Query`]: crate::system::Query
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///
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/// # Choosing a storage type
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///
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/// Components can be stored in the world using different strategies with their own performance implications.
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/// By default, components are added to the [`Table`] storage, which is optimized for query iteration.
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///
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/// Alternatively, components can be added to the [`SparseSet`] storage, which is optimized for component insertion and removal.
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/// This is achieved by adding an additional `#[component(storage = "SparseSet")]` attribute to the derive one:
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///
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/// ```
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/// # use bevy_ecs::component::Component;
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/// #
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/// #[derive(Component)]
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/// #[component(storage = "SparseSet")]
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/// struct ComponentA;
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/// ```
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///
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/// [`Table`]: crate::storage::Table
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/// [`SparseSet`]: crate::storage::SparseSet
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///
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/// # Required Components
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///
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/// Components can specify Required Components. If some [`Component`] `A` requires [`Component`] `B`, then when `A` is inserted,
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/// `B` will _also_ be initialized and inserted (if it was not manually specified).
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///
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/// The [`Default`] constructor will be used to initialize the component, by default:
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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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/// #[require(B)]
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/// struct A;
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///
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/// #[derive(Component, Default, PartialEq, Eq, Debug)]
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/// struct B(usize);
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///
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/// # let mut world = World::default();
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/// // This will implicitly also insert B with the Default constructor
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/// let id = world.spawn(A).id();
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/// assert_eq!(&B(0), world.entity(id).get::<B>().unwrap());
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///
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/// // This will _not_ implicitly insert B, because it was already provided
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/// world.spawn((A, B(11)));
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/// ```
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///
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/// Components can have more than one required 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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/// #[require(B, C)]
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/// struct A;
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///
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/// #[derive(Component, Default, PartialEq, Eq, Debug)]
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/// #[require(C)]
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/// struct B(usize);
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///
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/// #[derive(Component, Default, PartialEq, Eq, Debug)]
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/// struct C(u32);
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///
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/// # let mut world = World::default();
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/// // This will implicitly also insert B and C with their Default constructors
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/// let id = world.spawn(A).id();
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/// assert_eq!(&B(0), world.entity(id).get::<B>().unwrap());
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/// assert_eq!(&C(0), world.entity(id).get::<C>().unwrap());
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/// ```
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///
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/// You can also define a custom constructor function or closure:
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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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/// #[require(C(init_c))]
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/// struct A;
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///
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/// #[derive(Component, PartialEq, Eq, Debug)]
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/// #[require(C(|| C(20)))]
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/// struct B;
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///
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/// #[derive(Component, PartialEq, Eq, Debug)]
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/// struct C(usize);
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///
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/// fn init_c() -> C {
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/// C(10)
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/// }
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///
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/// # let mut world = World::default();
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/// // This will implicitly also insert C with the init_c() constructor
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/// let id = world.spawn(A).id();
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/// assert_eq!(&C(10), world.entity(id).get::<C>().unwrap());
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///
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/// // This will implicitly also insert C with the `|| C(20)` constructor closure
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/// let id = world.spawn(B).id();
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/// assert_eq!(&C(20), world.entity(id).get::<C>().unwrap());
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/// ```
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///
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/// Required components are _recursive_. This means, if a Required Component has required components,
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/// those components will _also_ be inserted if they are missing:
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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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/// #[require(B)]
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/// struct A;
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///
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/// #[derive(Component, Default, PartialEq, Eq, Debug)]
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/// #[require(C)]
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/// struct B(usize);
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///
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/// #[derive(Component, Default, PartialEq, Eq, Debug)]
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/// struct C(u32);
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///
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/// # let mut world = World::default();
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/// // This will implicitly also insert B and C with their Default constructors
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/// let id = world.spawn(A).id();
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/// assert_eq!(&B(0), world.entity(id).get::<B>().unwrap());
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/// assert_eq!(&C(0), world.entity(id).get::<C>().unwrap());
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/// ```
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///
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/// Note that cycles in the "component require tree" will result in stack overflows when attempting to
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/// insert a component.
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///
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/// This "multiple inheritance" pattern does mean that it is possible to have duplicate requires for a given type
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/// at different levels of the inheritance tree:
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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 X(usize);
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///
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/// #[derive(Component, Default)]
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/// #[require(X(|| X(1)))]
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/// struct Y;
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///
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/// #[derive(Component)]
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/// #[require(
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/// Y,
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/// X(|| X(2)),
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/// )]
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/// struct Z;
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///
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/// # let mut world = World::default();
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/// // In this case, the x2 constructor is used for X
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/// let id = world.spawn(Z).id();
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/// assert_eq!(2, world.entity(id).get::<X>().unwrap().0);
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/// ```
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///
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/// In general, this shouldn't happen often, but when it does the algorithm is simple and predictable:
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/// 1. Use all of the constructors (including default constructors) directly defined in the spawned component's require list
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/// 2. In the order the requires are defined in `#[require()]`, recursively visit the require list of each of the components in the list (this is a depth Depth First Search). When a constructor is found, it will only be used if one has not already been found.
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///
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/// From a user perspective, just think about this as the following:
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/// 1. Specifying a required component constructor for Foo directly on a spawned component Bar will result in that constructor being used (and overriding existing constructors lower in the inheritance tree). This is the classic "inheritance override" behavior people expect.
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/// 2. For cases where "multiple inheritance" results in constructor clashes, Components should be listed in "importance order". List a component earlier in the requirement list to initialize its inheritance tree earlier.
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///
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/// ## Registering required components at runtime
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///
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/// In most cases, required components should be registered using the `require` attribute as shown above.
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/// However, in some cases, it may be useful to register required components at runtime.
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///
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/// This can be done through [`World::register_required_components`] or [`World::register_required_components_with`]
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/// for the [`Default`] and custom constructors respectively:
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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 A;
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///
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/// #[derive(Component, Default, PartialEq, Eq, Debug)]
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/// struct B(usize);
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///
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/// #[derive(Component, PartialEq, Eq, Debug)]
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/// struct C(u32);
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///
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/// # let mut world = World::default();
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/// // Register B as required by A and C as required by B.
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/// world.register_required_components::<A, B>();
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/// world.register_required_components_with::<B, C>(|| C(2));
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///
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/// // This will implicitly also insert B with its Default constructor
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/// // and C with the custom constructor defined by B.
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/// let id = world.spawn(A).id();
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/// assert_eq!(&B(0), world.entity(id).get::<B>().unwrap());
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/// assert_eq!(&C(2), world.entity(id).get::<C>().unwrap());
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/// ```
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///
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/// Similar rules as before apply to duplicate requires fer a given type at different levels
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/// of the inheritance tree. `A` requiring `C` directly would take precedence over indirectly
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/// requiring it through `A` requiring `B` and `B` requiring `C`.
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///
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/// Unlike with the `require` attribute, directly requiring the same component multiple times
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/// for the same component will result in a panic. This is done to prevent conflicting constructors
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/// and confusing ordering dependencies.
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///
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/// Note that requirements must currently be registered before the requiring component is inserted
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/// into the world for the first time. Registering requirements after this will lead to a panic.
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///
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/// # Adding component's hooks
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///
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/// See [`ComponentHooks`] for a detailed explanation of component's hooks.
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///
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/// Alternatively to the example shown in [`ComponentHooks`]' documentation, hooks can be configured using following attributes:
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/// - `#[component(on_add = on_add_function)]`
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/// - `#[component(on_insert = on_insert_function)]`
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/// - `#[component(on_replace = on_replace_function)]`
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/// - `#[component(on_remove = on_remove_function)]`
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///
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/// ```
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/// # use bevy_ecs::component::Component;
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/// # use bevy_ecs::world::DeferredWorld;
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/// # use bevy_ecs::entity::Entity;
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/// # use bevy_ecs::component::ComponentId;
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/// #
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/// #[derive(Component)]
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/// #[component(on_add = my_on_add_hook)]
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/// #[component(on_insert = my_on_insert_hook)]
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/// // Another possible way of configuring hooks:
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/// // #[component(on_add = my_on_add_hook, on_insert = my_on_insert_hook)]
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/// //
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/// // We don't have a replace or remove hook, so we can leave them out:
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/// // #[component(on_replace = my_on_replace_hook, on_remove = my_on_remove_hook)]
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/// struct ComponentA;
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///
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/// fn my_on_add_hook(world: DeferredWorld, entity: Entity, id: ComponentId) {
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/// // ...
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/// }
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///
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/// // You can also omit writing some types using generics.
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/// fn my_on_insert_hook<T1, T2>(world: DeferredWorld, _: T1, _: T2) {
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/// // ...
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/// }
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/// ```
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///
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/// # Implementing the trait for foreign types
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///
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/// As a consequence of the [orphan rule], it is not possible to separate into two different crates the implementation of `Component` from the definition of a type.
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/// This means that it is not possible to directly have a type defined in a third party library as a component.
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/// This important limitation can be easily worked around using the [newtype pattern]:
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/// this makes it possible to locally define and implement `Component` for a tuple struct that wraps the foreign type.
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/// The following example gives a demonstration of this pattern.
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///
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/// ```
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/// // `Component` is defined in the `bevy_ecs` crate.
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/// use bevy_ecs::component::Component;
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///
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/// // `Duration` is defined in the `std` crate.
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/// use std::time::Duration;
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///
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/// // It is not possible to implement `Component` for `Duration` from this position, as they are
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/// // both foreign items, defined in an external crate. However, nothing prevents to define a new
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/// // `Cooldown` type that wraps `Duration`. As `Cooldown` is defined in a local crate, it is
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/// // possible to implement `Component` for it.
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/// #[derive(Component)]
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/// struct Cooldown(Duration);
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/// ```
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///
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/// [orphan rule]: https://doc.rust-lang.org/book/ch10-02-traits.html#implementing-a-trait-on-a-type
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/// [newtype pattern]: https://doc.rust-lang.org/book/ch19-03-advanced-traits.html#using-the-newtype-pattern-to-implement-external-traits-on-external-types
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///
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/// # `!Sync` Components
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/// A `!Sync` type cannot implement `Component`. However, it is possible to wrap a `Send` but not `Sync`
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/// type in [`SyncCell`] or the currently unstable [`Exclusive`] to make it `Sync`. This forces only
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/// having mutable access (`&mut T` only, never `&T`), but makes it safe to reference across multiple
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/// threads.
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///
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/// This will fail to compile since `RefCell` is `!Sync`.
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/// ```compile_fail
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/// # use std::cell::RefCell;
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/// # use bevy_ecs::component::Component;
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/// #[derive(Component)]
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/// struct NotSync {
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/// counter: RefCell<usize>,
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/// }
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/// ```
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///
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/// This will compile since the `RefCell` is wrapped with `SyncCell`.
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/// ```
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/// # use std::cell::RefCell;
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/// # use bevy_ecs::component::Component;
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/// use bevy_utils::synccell::SyncCell;
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///
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/// // This will compile.
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/// #[derive(Component)]
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/// struct ActuallySync {
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/// counter: SyncCell<RefCell<usize>>,
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/// }
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/// ```
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///
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/// [`SyncCell`]: bevy_utils::synccell::SyncCell
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/// [`Exclusive`]: https://doc.rust-lang.org/nightly/std/sync/struct.Exclusive.html
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#[diagnostic::on_unimplemented(
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message = "`{Self}` is not a `Component`",
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label = "invalid `Component`",
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note = "consider annotating `{Self}` with `#[derive(Component)]`"
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)]
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pub trait Component: Send + Sync + 'static {
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/// A constant indicating the storage type used for this component.
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const STORAGE_TYPE: StorageType;
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/// Called when registering this component, allowing mutable access to its [`ComponentHooks`].
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fn register_component_hooks(_hooks: &mut ComponentHooks) {}
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/// Registers required components.
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fn register_required_components(
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_component_id: ComponentId,
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_components: &mut Components,
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_storages: &mut Storages,
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_required_components: &mut RequiredComponents,
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_inheritance_depth: u16,
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) {
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}
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}
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/// The storage used for a specific component type.
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///
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/// # Examples
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/// The [`StorageType`] for a component is configured via the derive attribute
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///
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/// ```
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/// # use bevy_ecs::{prelude::*, component::*};
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/// #[derive(Component)]
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/// #[component(storage = "SparseSet")]
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/// struct A;
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/// ```
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#[derive(Debug, Copy, Clone, Default, Eq, PartialEq)]
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pub enum StorageType {
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/// Provides fast and cache-friendly iteration, but slower addition and removal of components.
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/// This is the default storage type.
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#[default]
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Table,
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/// Provides fast addition and removal of components, but slower iteration.
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SparseSet,
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}
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/// The type used for [`Component`] lifecycle hooks such as `on_add`, `on_insert` or `on_remove`
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pub type ComponentHook = for<'w> fn(DeferredWorld<'w>, Entity, ComponentId);
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/// [`World`]-mutating functions that run as part of lifecycle events of a [`Component`].
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///
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/// Hooks are functions that run when a component is added, overwritten, or removed from an entity.
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/// These are intended to be used for structural side effects that need to happen when a component is added or removed,
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/// and are not intended for general-purpose logic.
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///
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/// For example, you might use a hook to update a cached index when a component is added,
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/// to clean up resources when a component is removed,
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/// or to keep hierarchical data structures across entities in sync.
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///
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/// This information is stored in the [`ComponentInfo`] of the associated component.
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///
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/// There is two ways of configuring hooks for a component:
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/// 1. Defining the [`Component::register_component_hooks`] method (see [`Component`])
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/// 2. Using the [`World::register_component_hooks`] method
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///
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/// # Example 2
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///
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/// ```
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/// use bevy_ecs::prelude::*;
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/// use bevy_utils::HashSet;
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///
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/// #[derive(Component)]
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/// struct MyTrackedComponent;
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///
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/// #[derive(Resource, Default)]
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/// struct TrackedEntities(HashSet<Entity>);
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///
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/// let mut world = World::new();
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/// world.init_resource::<TrackedEntities>();
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///
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/// // No entities with `MyTrackedComponent` have been added yet, so we can safely add component hooks
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/// let mut tracked_component_query = world.query::<&MyTrackedComponent>();
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/// assert!(tracked_component_query.iter(&world).next().is_none());
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///
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/// world.register_component_hooks::<MyTrackedComponent>().on_add(|mut world, entity, _component_id| {
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/// let mut tracked_entities = world.resource_mut::<TrackedEntities>();
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/// tracked_entities.0.insert(entity);
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|
/// });
|
|
///
|
|
/// world.register_component_hooks::<MyTrackedComponent>().on_remove(|mut world, entity, _component_id| {
|
|
/// let mut tracked_entities = world.resource_mut::<TrackedEntities>();
|
|
/// tracked_entities.0.remove(&entity);
|
|
/// });
|
|
///
|
|
/// let entity = world.spawn(MyTrackedComponent).id();
|
|
/// let tracked_entities = world.resource::<TrackedEntities>();
|
|
/// assert!(tracked_entities.0.contains(&entity));
|
|
///
|
|
/// world.despawn(entity);
|
|
/// let tracked_entities = world.resource::<TrackedEntities>();
|
|
/// assert!(!tracked_entities.0.contains(&entity));
|
|
/// ```
|
|
#[derive(Debug, Clone, Default)]
|
|
pub struct ComponentHooks {
|
|
pub(crate) on_add: Option<ComponentHook>,
|
|
pub(crate) on_insert: Option<ComponentHook>,
|
|
pub(crate) on_replace: Option<ComponentHook>,
|
|
pub(crate) on_remove: Option<ComponentHook>,
|
|
}
|
|
|
|
impl ComponentHooks {
|
|
/// Register a [`ComponentHook`] that will be run when this component is added to an entity.
|
|
/// An `on_add` hook will always run before `on_insert` hooks. Spawning an entity counts as
|
|
/// adding all of its components.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Will panic if the component already has an `on_add` hook
|
|
pub fn on_add(&mut self, hook: ComponentHook) -> &mut Self {
|
|
self.try_on_add(hook)
|
|
.expect("Component id: {:?}, already has an on_add hook")
|
|
}
|
|
|
|
/// Register a [`ComponentHook`] that will be run when this component is added (with `.insert`)
|
|
/// or replaced.
|
|
///
|
|
/// An `on_insert` hook always runs after any `on_add` hooks (if the entity didn't already have the component).
|
|
///
|
|
/// # Warning
|
|
///
|
|
/// The hook won't run if the component is already present and is only mutated, such as in a system via a query.
|
|
/// As a result, this is *not* an appropriate mechanism for reliably updating indexes and other caches.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Will panic if the component already has an `on_insert` hook
|
|
pub fn on_insert(&mut self, hook: ComponentHook) -> &mut Self {
|
|
self.try_on_insert(hook)
|
|
.expect("Component id: {:?}, already has an on_insert hook")
|
|
}
|
|
|
|
/// Register a [`ComponentHook`] that will be run when this component is about to be dropped,
|
|
/// such as being replaced (with `.insert`) or removed.
|
|
///
|
|
/// If this component is inserted onto an entity that already has it, this hook will run before the value is replaced,
|
|
/// allowing access to the previous data just before it is dropped.
|
|
/// This hook does *not* run if the entity did not already have this component.
|
|
///
|
|
/// An `on_replace` hook always runs before any `on_remove` hooks (if the component is being removed from the entity).
|
|
///
|
|
/// # Warning
|
|
///
|
|
/// The hook won't run if the component is already present and is only mutated, such as in a system via a query.
|
|
/// As a result, this is *not* an appropriate mechanism for reliably updating indexes and other caches.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Will panic if the component already has an `on_replace` hook
|
|
pub fn on_replace(&mut self, hook: ComponentHook) -> &mut Self {
|
|
self.try_on_replace(hook)
|
|
.expect("Component id: {:?}, already has an on_replace hook")
|
|
}
|
|
|
|
/// Register a [`ComponentHook`] that will be run when this component is removed from an entity.
|
|
/// Despawning an entity counts as removing all of its components.
|
|
///
|
|
/// # Panics
|
|
///
|
|
/// Will panic if the component already has an `on_remove` hook
|
|
pub fn on_remove(&mut self, hook: ComponentHook) -> &mut Self {
|
|
self.try_on_remove(hook)
|
|
.expect("Component id: {:?}, already has an on_remove hook")
|
|
}
|
|
|
|
/// Attempt to register a [`ComponentHook`] that will be run when this component is added to an entity.
|
|
///
|
|
/// This is a fallible version of [`Self::on_add`].
|
|
///
|
|
/// Returns `None` if the component already has an `on_add` hook.
|
|
pub fn try_on_add(&mut self, hook: ComponentHook) -> Option<&mut Self> {
|
|
if self.on_add.is_some() {
|
|
return None;
|
|
}
|
|
self.on_add = Some(hook);
|
|
Some(self)
|
|
}
|
|
|
|
/// Attempt to register a [`ComponentHook`] that will be run when this component is added (with `.insert`)
|
|
///
|
|
/// This is a fallible version of [`Self::on_insert`].
|
|
///
|
|
/// Returns `None` if the component already has an `on_insert` hook.
|
|
pub fn try_on_insert(&mut self, hook: ComponentHook) -> Option<&mut Self> {
|
|
if self.on_insert.is_some() {
|
|
return None;
|
|
}
|
|
self.on_insert = Some(hook);
|
|
Some(self)
|
|
}
|
|
|
|
/// Attempt to register a [`ComponentHook`] that will be run when this component is replaced (with `.insert`) or removed
|
|
///
|
|
/// This is a fallible version of [`Self::on_replace`].
|
|
///
|
|
/// Returns `None` if the component already has an `on_replace` hook.
|
|
pub fn try_on_replace(&mut self, hook: ComponentHook) -> Option<&mut Self> {
|
|
if self.on_replace.is_some() {
|
|
return None;
|
|
}
|
|
self.on_replace = Some(hook);
|
|
Some(self)
|
|
}
|
|
|
|
/// Attempt to register a [`ComponentHook`] that will be run when this component is removed from an entity.
|
|
///
|
|
/// This is a fallible version of [`Self::on_remove`].
|
|
///
|
|
/// Returns `None` if the component already has an `on_remove` hook.
|
|
pub fn try_on_remove(&mut self, hook: ComponentHook) -> Option<&mut Self> {
|
|
if self.on_remove.is_some() {
|
|
return None;
|
|
}
|
|
self.on_remove = Some(hook);
|
|
Some(self)
|
|
}
|
|
}
|
|
|
|
/// Stores metadata for a type of component or resource stored in a specific [`World`].
|
|
#[derive(Debug, Clone)]
|
|
pub struct ComponentInfo {
|
|
id: ComponentId,
|
|
descriptor: ComponentDescriptor,
|
|
hooks: ComponentHooks,
|
|
required_components: RequiredComponents,
|
|
required_by: HashSet<ComponentId>,
|
|
}
|
|
|
|
impl ComponentInfo {
|
|
/// Returns a value uniquely identifying the current component.
|
|
#[inline]
|
|
pub fn id(&self) -> ComponentId {
|
|
self.id
|
|
}
|
|
|
|
/// Returns the name of the current component.
|
|
#[inline]
|
|
pub fn name(&self) -> &str {
|
|
&self.descriptor.name
|
|
}
|
|
|
|
/// Returns the [`TypeId`] of the underlying component type.
|
|
/// Returns `None` if the component does not correspond to a Rust type.
|
|
#[inline]
|
|
pub fn type_id(&self) -> Option<TypeId> {
|
|
self.descriptor.type_id
|
|
}
|
|
|
|
/// Returns the layout used to store values of this component in memory.
|
|
#[inline]
|
|
pub fn layout(&self) -> Layout {
|
|
self.descriptor.layout
|
|
}
|
|
|
|
#[inline]
|
|
/// Get the function which should be called to clean up values of
|
|
/// the underlying component type. This maps to the
|
|
/// [`Drop`] implementation for 'normal' Rust components
|
|
///
|
|
/// Returns `None` if values of the underlying component type don't
|
|
/// need to be dropped, e.g. as reported by [`needs_drop`].
|
|
pub fn drop(&self) -> Option<unsafe fn(OwningPtr<'_>)> {
|
|
self.descriptor.drop
|
|
}
|
|
|
|
/// Returns a value indicating the storage strategy for the current component.
|
|
#[inline]
|
|
pub fn storage_type(&self) -> StorageType {
|
|
self.descriptor.storage_type
|
|
}
|
|
|
|
/// Returns `true` if the underlying component type can be freely shared between threads.
|
|
/// If this returns `false`, then extra care must be taken to ensure that components
|
|
/// are not accessed from the wrong thread.
|
|
#[inline]
|
|
pub fn is_send_and_sync(&self) -> bool {
|
|
self.descriptor.is_send_and_sync
|
|
}
|
|
|
|
/// Create a new [`ComponentInfo`].
|
|
pub(crate) fn new(id: ComponentId, descriptor: ComponentDescriptor) -> Self {
|
|
ComponentInfo {
|
|
id,
|
|
descriptor,
|
|
hooks: Default::default(),
|
|
required_components: Default::default(),
|
|
required_by: Default::default(),
|
|
}
|
|
}
|
|
|
|
/// Update the given flags to include any [`ComponentHook`] registered to self
|
|
#[inline]
|
|
pub(crate) fn update_archetype_flags(&self, flags: &mut ArchetypeFlags) {
|
|
if self.hooks().on_add.is_some() {
|
|
flags.insert(ArchetypeFlags::ON_ADD_HOOK);
|
|
}
|
|
if self.hooks().on_insert.is_some() {
|
|
flags.insert(ArchetypeFlags::ON_INSERT_HOOK);
|
|
}
|
|
if self.hooks().on_replace.is_some() {
|
|
flags.insert(ArchetypeFlags::ON_REPLACE_HOOK);
|
|
}
|
|
if self.hooks().on_remove.is_some() {
|
|
flags.insert(ArchetypeFlags::ON_REMOVE_HOOK);
|
|
}
|
|
}
|
|
|
|
/// Provides a reference to the collection of hooks associated with this [`Component`]
|
|
pub fn hooks(&self) -> &ComponentHooks {
|
|
&self.hooks
|
|
}
|
|
|
|
/// Retrieves the [`RequiredComponents`] collection, which contains all required components (and their constructors)
|
|
/// needed by this component. This includes _recursive_ required components.
|
|
pub fn required_components(&self) -> &RequiredComponents {
|
|
&self.required_components
|
|
}
|
|
}
|
|
|
|
/// A value which uniquely identifies the type of a [`Component`] or [`Resource`] within a
|
|
/// [`World`].
|
|
///
|
|
/// Each time a new `Component` type is registered within a `World` using
|
|
/// e.g. [`World::register_component`] or [`World::register_component_with_descriptor`]
|
|
/// or a Resource with e.g. [`World::init_resource`],
|
|
/// a corresponding `ComponentId` is created to track it.
|
|
///
|
|
/// While the distinction between `ComponentId` and [`TypeId`] may seem superficial, breaking them
|
|
/// into two separate but related concepts allows components to exist outside of Rust's type system.
|
|
/// Each Rust type registered as a `Component` will have a corresponding `ComponentId`, but additional
|
|
/// `ComponentId`s may exist in a `World` to track components which cannot be
|
|
/// represented as Rust types for scripting or other advanced use-cases.
|
|
///
|
|
/// A `ComponentId` is tightly coupled to its parent `World`. Attempting to use a `ComponentId` from
|
|
/// one `World` to access the metadata of a `Component` in a different `World` is undefined behavior
|
|
/// and must not be attempted.
|
|
///
|
|
/// Given a type `T` which implements [`Component`], the `ComponentId` for `T` can be retrieved
|
|
/// from a `World` using [`World::component_id()`] or via [`Components::component_id()`]. Access
|
|
/// to the `ComponentId` for a [`Resource`] is available via [`Components::resource_id()`].
|
|
#[derive(Debug, Copy, Clone, Hash, Ord, PartialOrd, Eq, PartialEq)]
|
|
#[cfg_attr(
|
|
feature = "bevy_reflect",
|
|
derive(Reflect),
|
|
reflect(Debug, Hash, PartialEq)
|
|
)]
|
|
pub struct ComponentId(usize);
|
|
|
|
impl ComponentId {
|
|
/// Creates a new [`ComponentId`].
|
|
///
|
|
/// The `index` is a unique value associated with each type of component in a given world.
|
|
/// Usually, this value is taken from a counter incremented for each type of component registered with the world.
|
|
#[inline]
|
|
pub const fn new(index: usize) -> ComponentId {
|
|
ComponentId(index)
|
|
}
|
|
|
|
/// Returns the index of the current component.
|
|
#[inline]
|
|
pub fn index(self) -> usize {
|
|
self.0
|
|
}
|
|
}
|
|
|
|
impl SparseSetIndex for ComponentId {
|
|
#[inline]
|
|
fn sparse_set_index(&self) -> usize {
|
|
self.index()
|
|
}
|
|
|
|
#[inline]
|
|
fn get_sparse_set_index(value: usize) -> Self {
|
|
Self(value)
|
|
}
|
|
}
|
|
|
|
/// A value describing a component or resource, which may or may not correspond to a Rust type.
|
|
#[derive(Clone)]
|
|
pub struct ComponentDescriptor {
|
|
name: Cow<'static, str>,
|
|
// SAFETY: This must remain private. It must match the statically known StorageType of the
|
|
// associated rust component type if one exists.
|
|
storage_type: StorageType,
|
|
// SAFETY: This must remain private. It must only be set to "true" if this component is
|
|
// actually Send + Sync
|
|
is_send_and_sync: bool,
|
|
type_id: Option<TypeId>,
|
|
layout: Layout,
|
|
// SAFETY: this function must be safe to call with pointers pointing to items of the type
|
|
// this descriptor describes.
|
|
// None if the underlying type doesn't need to be dropped
|
|
drop: Option<for<'a> unsafe fn(OwningPtr<'a>)>,
|
|
}
|
|
|
|
// We need to ignore the `drop` field in our `Debug` impl
|
|
impl Debug for ComponentDescriptor {
|
|
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
|
|
f.debug_struct("ComponentDescriptor")
|
|
.field("name", &self.name)
|
|
.field("storage_type", &self.storage_type)
|
|
.field("is_send_and_sync", &self.is_send_and_sync)
|
|
.field("type_id", &self.type_id)
|
|
.field("layout", &self.layout)
|
|
.finish()
|
|
}
|
|
}
|
|
|
|
impl ComponentDescriptor {
|
|
/// # Safety
|
|
///
|
|
/// `x` must point to a valid value of type `T`.
|
|
unsafe fn drop_ptr<T>(x: OwningPtr<'_>) {
|
|
// SAFETY: Contract is required to be upheld by the caller.
|
|
unsafe {
|
|
x.drop_as::<T>();
|
|
}
|
|
}
|
|
|
|
/// Create a new `ComponentDescriptor` for the type `T`.
|
|
pub fn new<T: Component>() -> Self {
|
|
Self {
|
|
name: Cow::Borrowed(core::any::type_name::<T>()),
|
|
storage_type: T::STORAGE_TYPE,
|
|
is_send_and_sync: true,
|
|
type_id: Some(TypeId::of::<T>()),
|
|
layout: Layout::new::<T>(),
|
|
drop: needs_drop::<T>().then_some(Self::drop_ptr::<T> as _),
|
|
}
|
|
}
|
|
|
|
/// Create a new `ComponentDescriptor`.
|
|
///
|
|
/// # Safety
|
|
/// - the `drop` fn must be usable on a pointer with a value of the layout `layout`
|
|
/// - the component type must be safe to access from any thread (Send + Sync in rust terms)
|
|
pub unsafe fn new_with_layout(
|
|
name: impl Into<Cow<'static, str>>,
|
|
storage_type: StorageType,
|
|
layout: Layout,
|
|
drop: Option<for<'a> unsafe fn(OwningPtr<'a>)>,
|
|
) -> Self {
|
|
Self {
|
|
name: name.into(),
|
|
storage_type,
|
|
is_send_and_sync: true,
|
|
type_id: None,
|
|
layout,
|
|
drop,
|
|
}
|
|
}
|
|
|
|
/// Create a new `ComponentDescriptor` for a resource.
|
|
///
|
|
/// The [`StorageType`] for resources is always [`StorageType::Table`].
|
|
pub fn new_resource<T: Resource>() -> Self {
|
|
Self {
|
|
name: Cow::Borrowed(core::any::type_name::<T>()),
|
|
// PERF: `SparseStorage` may actually be a more
|
|
// reasonable choice as `storage_type` for resources.
|
|
storage_type: StorageType::Table,
|
|
is_send_and_sync: true,
|
|
type_id: Some(TypeId::of::<T>()),
|
|
layout: Layout::new::<T>(),
|
|
drop: needs_drop::<T>().then_some(Self::drop_ptr::<T> as _),
|
|
}
|
|
}
|
|
|
|
fn new_non_send<T: Any>(storage_type: StorageType) -> Self {
|
|
Self {
|
|
name: Cow::Borrowed(core::any::type_name::<T>()),
|
|
storage_type,
|
|
is_send_and_sync: false,
|
|
type_id: Some(TypeId::of::<T>()),
|
|
layout: Layout::new::<T>(),
|
|
drop: needs_drop::<T>().then_some(Self::drop_ptr::<T> as _),
|
|
}
|
|
}
|
|
|
|
/// Returns a value indicating the storage strategy for the current component.
|
|
#[inline]
|
|
pub fn storage_type(&self) -> StorageType {
|
|
self.storage_type
|
|
}
|
|
|
|
/// Returns the [`TypeId`] of the underlying component type.
|
|
/// Returns `None` if the component does not correspond to a Rust type.
|
|
#[inline]
|
|
pub fn type_id(&self) -> Option<TypeId> {
|
|
self.type_id
|
|
}
|
|
|
|
/// Returns the name of the current component.
|
|
#[inline]
|
|
pub fn name(&self) -> &str {
|
|
self.name.as_ref()
|
|
}
|
|
}
|
|
|
|
/// Stores metadata associated with each kind of [`Component`] in a given [`World`].
|
|
#[derive(Debug, Default)]
|
|
pub struct Components {
|
|
components: Vec<ComponentInfo>,
|
|
indices: TypeIdMap<ComponentId>,
|
|
resource_indices: TypeIdMap<ComponentId>,
|
|
}
|
|
|
|
impl Components {
|
|
/// Registers a [`Component`] of type `T` with this instance.
|
|
/// If a component of this type has already been registered, this will return
|
|
/// the ID of the pre-existing component.
|
|
///
|
|
/// # See also
|
|
///
|
|
/// * [`Components::component_id()`]
|
|
/// * [`Components::register_component_with_descriptor()`]
|
|
#[inline]
|
|
pub fn register_component<T: Component>(&mut self, storages: &mut Storages) -> ComponentId {
|
|
let mut registered = false;
|
|
let id = {
|
|
let Components {
|
|
indices,
|
|
components,
|
|
..
|
|
} = self;
|
|
let type_id = TypeId::of::<T>();
|
|
*indices.entry(type_id).or_insert_with(|| {
|
|
let id = Components::register_component_inner(
|
|
components,
|
|
storages,
|
|
ComponentDescriptor::new::<T>(),
|
|
);
|
|
registered = true;
|
|
id
|
|
})
|
|
};
|
|
if registered {
|
|
let mut required_components = RequiredComponents::default();
|
|
T::register_required_components(id, self, storages, &mut required_components, 0);
|
|
let info = &mut self.components[id.index()];
|
|
T::register_component_hooks(&mut info.hooks);
|
|
info.required_components = required_components;
|
|
}
|
|
id
|
|
}
|
|
|
|
/// Registers a component described by `descriptor`.
|
|
///
|
|
/// # Note
|
|
///
|
|
/// If this method is called multiple times with identical descriptors, a distinct [`ComponentId`]
|
|
/// will be created for each one.
|
|
///
|
|
/// # See also
|
|
///
|
|
/// * [`Components::component_id()`]
|
|
/// * [`Components::register_component()`]
|
|
pub fn register_component_with_descriptor(
|
|
&mut self,
|
|
storages: &mut Storages,
|
|
descriptor: ComponentDescriptor,
|
|
) -> ComponentId {
|
|
Components::register_component_inner(&mut self.components, storages, descriptor)
|
|
}
|
|
|
|
#[inline]
|
|
fn register_component_inner(
|
|
components: &mut Vec<ComponentInfo>,
|
|
storages: &mut Storages,
|
|
descriptor: ComponentDescriptor,
|
|
) -> ComponentId {
|
|
let component_id = ComponentId(components.len());
|
|
let info = ComponentInfo::new(component_id, descriptor);
|
|
if info.descriptor.storage_type == StorageType::SparseSet {
|
|
storages.sparse_sets.get_or_insert(&info);
|
|
}
|
|
components.push(info);
|
|
component_id
|
|
}
|
|
|
|
/// Returns the number of components registered with this instance.
|
|
#[inline]
|
|
pub fn len(&self) -> usize {
|
|
self.components.len()
|
|
}
|
|
|
|
/// Returns `true` if there are no components registered with this instance. Otherwise, this returns `false`.
|
|
#[inline]
|
|
pub fn is_empty(&self) -> bool {
|
|
self.components.len() == 0
|
|
}
|
|
|
|
/// Gets the metadata associated with the given component.
|
|
///
|
|
/// This will return an incorrect result if `id` did not come from the same world as `self`. It may return `None` or a garbage value.
|
|
#[inline]
|
|
pub fn get_info(&self, id: ComponentId) -> Option<&ComponentInfo> {
|
|
self.components.get(id.0)
|
|
}
|
|
|
|
/// Returns the name associated with the given component.
|
|
///
|
|
/// This will return an incorrect result if `id` did not come from the same world as `self`. It may return `None` or a garbage value.
|
|
#[inline]
|
|
pub fn get_name(&self, id: ComponentId) -> Option<&str> {
|
|
self.get_info(id).map(ComponentInfo::name)
|
|
}
|
|
|
|
/// Gets the metadata associated with the given component.
|
|
/// # Safety
|
|
///
|
|
/// `id` must be a valid [`ComponentId`]
|
|
#[inline]
|
|
pub unsafe fn get_info_unchecked(&self, id: ComponentId) -> &ComponentInfo {
|
|
debug_assert!(id.index() < self.components.len());
|
|
// SAFETY: The caller ensures `id` is valid.
|
|
unsafe { self.components.get_unchecked(id.0) }
|
|
}
|
|
|
|
#[inline]
|
|
pub(crate) fn get_hooks_mut(&mut self, id: ComponentId) -> Option<&mut ComponentHooks> {
|
|
self.components.get_mut(id.0).map(|info| &mut info.hooks)
|
|
}
|
|
|
|
#[inline]
|
|
pub(crate) fn get_required_components_mut(
|
|
&mut self,
|
|
id: ComponentId,
|
|
) -> Option<&mut RequiredComponents> {
|
|
self.components
|
|
.get_mut(id.0)
|
|
.map(|info| &mut info.required_components)
|
|
}
|
|
|
|
/// Registers the given component `R` and [required components] inherited from it as required by `T`.
|
|
///
|
|
/// When `T` is added to an entity, `R` will also be added if it was not already provided.
|
|
/// The given `constructor` will be used for the creation of `R`.
|
|
///
|
|
/// [required components]: Component#required-components
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// The given component IDs `required` and `requiree` must be valid.
|
|
///
|
|
/// # Errors
|
|
///
|
|
/// Returns a [`RequiredComponentsError`] if the `required` component is already a directly required component for the `requiree`.
|
|
///
|
|
/// Indirect requirements through other components are allowed. In those cases, the more specific
|
|
/// registration will be used.
|
|
pub(crate) unsafe fn register_required_components<R: Component>(
|
|
&mut self,
|
|
required: ComponentId,
|
|
requiree: ComponentId,
|
|
constructor: fn() -> R,
|
|
) -> Result<(), RequiredComponentsError> {
|
|
// SAFETY: The caller ensures that the `requiree` is valid.
|
|
let required_components = unsafe {
|
|
self.get_required_components_mut(requiree)
|
|
.debug_checked_unwrap()
|
|
};
|
|
|
|
// Cannot directly require the same component twice.
|
|
if required_components
|
|
.0
|
|
.get(&required)
|
|
.is_some_and(|c| c.inheritance_depth == 0)
|
|
{
|
|
return Err(RequiredComponentsError::DuplicateRegistration(
|
|
requiree, required,
|
|
));
|
|
}
|
|
|
|
// Register the required component for the requiree.
|
|
// This is a direct requirement with a depth of `0`.
|
|
required_components.register_by_id(required, constructor, 0);
|
|
|
|
// Add the requiree to the list of components that require the required component.
|
|
// SAFETY: The component is in the list of required components, so it must exist already.
|
|
let required_by = unsafe { self.get_required_by_mut(required).debug_checked_unwrap() };
|
|
required_by.insert(requiree);
|
|
|
|
// SAFETY: The caller ensures that the `requiree` and `required` components are valid.
|
|
let inherited_requirements =
|
|
unsafe { self.register_inherited_required_components(requiree, required) };
|
|
|
|
// Propagate the new required components up the chain to all components that require the requiree.
|
|
if let Some(required_by) = self.get_required_by(requiree).cloned() {
|
|
for &required_by_id in required_by.iter() {
|
|
// SAFETY: The component is in the list of required components, so it must exist already.
|
|
let required_components = unsafe {
|
|
self.get_required_components_mut(required_by_id)
|
|
.debug_checked_unwrap()
|
|
};
|
|
|
|
// Register the original required component for the requiree.
|
|
// The inheritance depth is `1` since this is a component required by the original requiree.
|
|
required_components.register_by_id(required, constructor, 1);
|
|
|
|
for (component_id, component) in inherited_requirements.iter() {
|
|
// Register the required component.
|
|
// The inheritance depth is increased by `1` since this is a component required by the original required component.
|
|
// SAFETY: Component ID and constructor match the ones on the original requiree.
|
|
// The original requiree is responsible for making sure the registration is safe.
|
|
unsafe {
|
|
required_components.register_dynamic(
|
|
*component_id,
|
|
component.constructor.clone(),
|
|
component.inheritance_depth + 1,
|
|
);
|
|
};
|
|
}
|
|
}
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
|
|
/// Registers the components inherited from `required` for the given `requiree`,
|
|
/// returning the requirements in a list.
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// The given component IDs `requiree` and `required` must be valid.
|
|
unsafe fn register_inherited_required_components(
|
|
&mut self,
|
|
requiree: ComponentId,
|
|
required: ComponentId,
|
|
) -> Vec<(ComponentId, RequiredComponent)> {
|
|
// Get required components inherited from the `required` component.
|
|
// SAFETY: The caller ensures that the `required` component is valid.
|
|
let required_component_info = unsafe { self.get_info(required).debug_checked_unwrap() };
|
|
let inherited_requirements: Vec<(ComponentId, RequiredComponent)> = required_component_info
|
|
.required_components()
|
|
.0
|
|
.iter()
|
|
.map(|(component_id, required_component)| {
|
|
(
|
|
*component_id,
|
|
RequiredComponent {
|
|
constructor: required_component.constructor.clone(),
|
|
// Add `1` to the inheritance depth since this will be registered
|
|
// for the component that requires `required`.
|
|
inheritance_depth: required_component.inheritance_depth + 1,
|
|
},
|
|
)
|
|
})
|
|
.collect();
|
|
|
|
// Register the new required components.
|
|
for (component_id, component) in inherited_requirements.iter().cloned() {
|
|
// SAFETY: The caller ensures that the `requiree` is valid.
|
|
let required_components = unsafe {
|
|
self.get_required_components_mut(requiree)
|
|
.debug_checked_unwrap()
|
|
};
|
|
|
|
// Register the required component for the requiree.
|
|
// SAFETY: Component ID and constructor match the ones on the original requiree.
|
|
unsafe {
|
|
required_components.register_dynamic(
|
|
component_id,
|
|
component.constructor,
|
|
component.inheritance_depth,
|
|
);
|
|
};
|
|
|
|
// Add the requiree to the list of components that require the required component.
|
|
// SAFETY: The caller ensures that the required components are valid.
|
|
let required_by = unsafe {
|
|
self.get_required_by_mut(component_id)
|
|
.debug_checked_unwrap()
|
|
};
|
|
required_by.insert(requiree);
|
|
}
|
|
|
|
inherited_requirements
|
|
}
|
|
|
|
// NOTE: This should maybe be private, but it is currently public so that `bevy_ecs_macros` can use it.
|
|
// We can't directly move this there either, because this uses `Components::get_required_by_mut`,
|
|
// which is private, and could be equally risky to expose to users.
|
|
/// Registers the given component `R` as a [required component] for `T`,
|
|
/// and adds `T` to the list of requirees for `R`.
|
|
///
|
|
/// The given `inheritance_depth` determines how many levels of inheritance deep the requirement is.
|
|
/// A direct requirement has a depth of `0`, and each level of inheritance increases the depth by `1`.
|
|
/// Lower depths are more specific requirements, and can override existing less specific registrations.
|
|
///
|
|
/// This method does *not* recursively register required components for components required by `R`,
|
|
/// nor does it register them for components that require `T`.
|
|
///
|
|
/// Only use this method if you know what you are doing. In most cases, you should instead use [`World::register_required_components`],
|
|
/// or the equivalent method in `bevy_app::App`.
|
|
///
|
|
/// [required component]: Component#required-components
|
|
#[doc(hidden)]
|
|
pub fn register_required_components_manual<T: Component, R: Component>(
|
|
&mut self,
|
|
storages: &mut Storages,
|
|
required_components: &mut RequiredComponents,
|
|
constructor: fn() -> R,
|
|
inheritance_depth: u16,
|
|
) {
|
|
let requiree = self.register_component::<T>(storages);
|
|
let required = self.register_component::<R>(storages);
|
|
|
|
// SAFETY: We just created the components.
|
|
unsafe {
|
|
self.register_required_components_manual_unchecked::<R>(
|
|
requiree,
|
|
required,
|
|
required_components,
|
|
constructor,
|
|
inheritance_depth,
|
|
);
|
|
}
|
|
}
|
|
|
|
/// Registers the given component `R` as a [required component] for `T`,
|
|
/// and adds `T` to the list of requirees for `R`.
|
|
///
|
|
/// The given `inheritance_depth` determines how many levels of inheritance deep the requirement is.
|
|
/// A direct requirement has a depth of `0`, and each level of inheritance increases the depth by `1`.
|
|
/// Lower depths are more specific requirements, and can override existing less specific registrations.
|
|
///
|
|
/// This method does *not* recursively register required components for components required by `R`,
|
|
/// nor does it register them for components that require `T`.
|
|
///
|
|
/// [required component]: Component#required-components
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// The given component IDs `required` and `requiree` must be valid.
|
|
pub(crate) unsafe fn register_required_components_manual_unchecked<R: Component>(
|
|
&mut self,
|
|
requiree: ComponentId,
|
|
required: ComponentId,
|
|
required_components: &mut RequiredComponents,
|
|
constructor: fn() -> R,
|
|
inheritance_depth: u16,
|
|
) {
|
|
// Components cannot require themselves.
|
|
if required == requiree {
|
|
return;
|
|
}
|
|
|
|
// Register the required component `R` for the requiree.
|
|
required_components.register_by_id(required, constructor, inheritance_depth);
|
|
|
|
// Add the requiree to the list of components that require `R`.
|
|
// SAFETY: The caller ensures that the component ID is valid.
|
|
// Assuming it is valid, the component is in the list of required components, so it must exist already.
|
|
let required_by = unsafe { self.get_required_by_mut(required).debug_checked_unwrap() };
|
|
required_by.insert(requiree);
|
|
}
|
|
|
|
#[inline]
|
|
pub(crate) fn get_required_by(&self, id: ComponentId) -> Option<&HashSet<ComponentId>> {
|
|
self.components.get(id.0).map(|info| &info.required_by)
|
|
}
|
|
|
|
#[inline]
|
|
pub(crate) fn get_required_by_mut(
|
|
&mut self,
|
|
id: ComponentId,
|
|
) -> Option<&mut HashSet<ComponentId>> {
|
|
self.components
|
|
.get_mut(id.0)
|
|
.map(|info| &mut info.required_by)
|
|
}
|
|
|
|
/// Type-erased equivalent of [`Components::component_id()`].
|
|
#[inline]
|
|
pub fn get_id(&self, type_id: TypeId) -> Option<ComponentId> {
|
|
self.indices.get(&type_id).copied()
|
|
}
|
|
|
|
/// Returns the [`ComponentId`] of the given [`Component`] type `T`.
|
|
///
|
|
/// The returned `ComponentId` is specific to the `Components` instance
|
|
/// it was retrieved from and should not be used with another `Components`
|
|
/// instance.
|
|
///
|
|
/// Returns [`None`] if the `Component` type has not
|
|
/// yet been initialized using [`Components::register_component()`].
|
|
///
|
|
/// ```
|
|
/// use bevy_ecs::prelude::*;
|
|
///
|
|
/// let mut world = World::new();
|
|
///
|
|
/// #[derive(Component)]
|
|
/// struct ComponentA;
|
|
///
|
|
/// let component_a_id = world.register_component::<ComponentA>();
|
|
///
|
|
/// assert_eq!(component_a_id, world.components().component_id::<ComponentA>().unwrap())
|
|
/// ```
|
|
///
|
|
/// # See also
|
|
///
|
|
/// * [`Components::get_id()`]
|
|
/// * [`Components::resource_id()`]
|
|
/// * [`World::component_id()`]
|
|
#[inline]
|
|
pub fn component_id<T: Component>(&self) -> Option<ComponentId> {
|
|
self.get_id(TypeId::of::<T>())
|
|
}
|
|
|
|
/// Type-erased equivalent of [`Components::resource_id()`].
|
|
#[inline]
|
|
pub fn get_resource_id(&self, type_id: TypeId) -> Option<ComponentId> {
|
|
self.resource_indices.get(&type_id).copied()
|
|
}
|
|
|
|
/// Returns the [`ComponentId`] of the given [`Resource`] type `T`.
|
|
///
|
|
/// The returned `ComponentId` is specific to the `Components` instance
|
|
/// it was retrieved from and should not be used with another `Components`
|
|
/// instance.
|
|
///
|
|
/// Returns [`None`] if the `Resource` type has not
|
|
/// yet been initialized using [`Components::register_resource()`].
|
|
///
|
|
/// ```
|
|
/// use bevy_ecs::prelude::*;
|
|
///
|
|
/// let mut world = World::new();
|
|
///
|
|
/// #[derive(Resource, Default)]
|
|
/// struct ResourceA;
|
|
///
|
|
/// let resource_a_id = world.init_resource::<ResourceA>();
|
|
///
|
|
/// assert_eq!(resource_a_id, world.components().resource_id::<ResourceA>().unwrap())
|
|
/// ```
|
|
///
|
|
/// # See also
|
|
///
|
|
/// * [`Components::component_id()`]
|
|
/// * [`Components::get_resource_id()`]
|
|
#[inline]
|
|
pub fn resource_id<T: Resource>(&self) -> Option<ComponentId> {
|
|
self.get_resource_id(TypeId::of::<T>())
|
|
}
|
|
|
|
/// Registers a [`Resource`] of type `T` with this instance.
|
|
/// If a resource of this type has already been registered, this will return
|
|
/// the ID of the pre-existing resource.
|
|
///
|
|
/// # See also
|
|
///
|
|
/// * [`Components::resource_id()`]
|
|
/// * [`Components::register_resource_with_descriptor()`]
|
|
#[inline]
|
|
pub fn register_resource<T: Resource>(&mut self) -> ComponentId {
|
|
// SAFETY: The [`ComponentDescriptor`] matches the [`TypeId`]
|
|
unsafe {
|
|
self.get_or_register_resource_with(TypeId::of::<T>(), || {
|
|
ComponentDescriptor::new_resource::<T>()
|
|
})
|
|
}
|
|
}
|
|
|
|
/// Registers a [`Resource`] described by `descriptor`.
|
|
///
|
|
/// # Note
|
|
///
|
|
/// If this method is called multiple times with identical descriptors, a distinct [`ComponentId`]
|
|
/// will be created for each one.
|
|
///
|
|
/// # See also
|
|
///
|
|
/// * [`Components::resource_id()`]
|
|
/// * [`Components::register_resource()`]
|
|
pub fn register_resource_with_descriptor(
|
|
&mut self,
|
|
descriptor: ComponentDescriptor,
|
|
) -> ComponentId {
|
|
Components::register_resource_inner(&mut self.components, descriptor)
|
|
}
|
|
|
|
/// Registers a [non-send resource](crate::system::NonSend) of type `T` with this instance.
|
|
/// If a resource of this type has already been registered, this will return
|
|
/// the ID of the pre-existing resource.
|
|
#[inline]
|
|
pub fn register_non_send<T: Any>(&mut self) -> ComponentId {
|
|
// SAFETY: The [`ComponentDescriptor`] matches the [`TypeId`]
|
|
unsafe {
|
|
self.get_or_register_resource_with(TypeId::of::<T>(), || {
|
|
ComponentDescriptor::new_non_send::<T>(StorageType::default())
|
|
})
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// The [`ComponentDescriptor`] must match the [`TypeId`]
|
|
#[inline]
|
|
unsafe fn get_or_register_resource_with(
|
|
&mut self,
|
|
type_id: TypeId,
|
|
func: impl FnOnce() -> ComponentDescriptor,
|
|
) -> ComponentId {
|
|
let components = &mut self.components;
|
|
*self.resource_indices.entry(type_id).or_insert_with(|| {
|
|
let descriptor = func();
|
|
Components::register_resource_inner(components, descriptor)
|
|
})
|
|
}
|
|
|
|
#[inline]
|
|
fn register_resource_inner(
|
|
components: &mut Vec<ComponentInfo>,
|
|
descriptor: ComponentDescriptor,
|
|
) -> ComponentId {
|
|
let component_id = ComponentId(components.len());
|
|
components.push(ComponentInfo::new(component_id, descriptor));
|
|
component_id
|
|
}
|
|
|
|
/// Gets an iterator over all components registered with this instance.
|
|
pub fn iter(&self) -> impl Iterator<Item = &ComponentInfo> + '_ {
|
|
self.components.iter()
|
|
}
|
|
}
|
|
|
|
/// A value that tracks when a system ran relative to other systems.
|
|
/// This is used to power change detection.
|
|
///
|
|
/// *Note* that a system that hasn't been run yet has a `Tick` of 0.
|
|
#[derive(Copy, Clone, Default, Debug, Eq, Hash, PartialEq)]
|
|
#[cfg_attr(
|
|
feature = "bevy_reflect",
|
|
derive(Reflect),
|
|
reflect(Debug, Hash, PartialEq)
|
|
)]
|
|
pub struct Tick {
|
|
tick: u32,
|
|
}
|
|
|
|
impl Tick {
|
|
/// The maximum relative age for a change tick.
|
|
/// The value of this is equal to [`MAX_CHANGE_AGE`].
|
|
///
|
|
/// Since change detection will not work for any ticks older than this,
|
|
/// ticks are periodically scanned to ensure their relative values are below this.
|
|
pub const MAX: Self = Self::new(MAX_CHANGE_AGE);
|
|
|
|
/// Creates a new [`Tick`] wrapping the given value.
|
|
#[inline]
|
|
pub const fn new(tick: u32) -> Self {
|
|
Self { tick }
|
|
}
|
|
|
|
/// Gets the value of this change tick.
|
|
#[inline]
|
|
pub const fn get(self) -> u32 {
|
|
self.tick
|
|
}
|
|
|
|
/// Sets the value of this change tick.
|
|
#[inline]
|
|
pub fn set(&mut self, tick: u32) {
|
|
self.tick = tick;
|
|
}
|
|
|
|
/// Returns `true` if this `Tick` occurred since the system's `last_run`.
|
|
///
|
|
/// `this_run` is the current tick of the system, used as a reference to help deal with wraparound.
|
|
#[inline]
|
|
pub fn is_newer_than(self, last_run: Tick, this_run: Tick) -> bool {
|
|
// This works even with wraparound because the world tick (`this_run`) is always "newer" than
|
|
// `last_run` and `self.tick`, and we scan periodically to clamp `ComponentTicks` values
|
|
// so they never get older than `u32::MAX` (the difference would overflow).
|
|
//
|
|
// The clamp here ensures determinism (since scans could differ between app runs).
|
|
let ticks_since_insert = this_run.relative_to(self).tick.min(MAX_CHANGE_AGE);
|
|
let ticks_since_system = this_run.relative_to(last_run).tick.min(MAX_CHANGE_AGE);
|
|
|
|
ticks_since_system > ticks_since_insert
|
|
}
|
|
|
|
/// Returns a change tick representing the relationship between `self` and `other`.
|
|
#[inline]
|
|
pub(crate) fn relative_to(self, other: Self) -> Self {
|
|
let tick = self.tick.wrapping_sub(other.tick);
|
|
Self { tick }
|
|
}
|
|
|
|
/// Wraps this change tick's value if it exceeds [`Tick::MAX`].
|
|
///
|
|
/// Returns `true` if wrapping was performed. Otherwise, returns `false`.
|
|
#[inline]
|
|
pub(crate) fn check_tick(&mut self, tick: Tick) -> bool {
|
|
let age = tick.relative_to(*self);
|
|
// This comparison assumes that `age` has not overflowed `u32::MAX` before, which will be true
|
|
// so long as this check always runs before that can happen.
|
|
if age.get() > Self::MAX.get() {
|
|
*self = tick.relative_to(Self::MAX);
|
|
true
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Interior-mutable access to the [`Tick`]s for a single component or resource.
|
|
#[derive(Copy, Clone, Debug)]
|
|
pub struct TickCells<'a> {
|
|
/// The tick indicating when the value was added to the world.
|
|
pub added: &'a UnsafeCell<Tick>,
|
|
/// The tick indicating the last time the value was modified.
|
|
pub changed: &'a UnsafeCell<Tick>,
|
|
}
|
|
|
|
impl<'a> TickCells<'a> {
|
|
/// # Safety
|
|
/// All cells contained within must uphold the safety invariants of [`UnsafeCellDeref::read`].
|
|
#[inline]
|
|
pub(crate) unsafe fn read(&self) -> ComponentTicks {
|
|
ComponentTicks {
|
|
// SAFETY: The callers uphold the invariants for `read`.
|
|
added: unsafe { self.added.read() },
|
|
// SAFETY: The callers uphold the invariants for `read`.
|
|
changed: unsafe { self.changed.read() },
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Records when a component or resource was added and when it was last mutably dereferenced (or added).
|
|
#[derive(Copy, Clone, Debug)]
|
|
#[cfg_attr(feature = "bevy_reflect", derive(Reflect), reflect(Debug))]
|
|
pub struct ComponentTicks {
|
|
pub(crate) added: Tick,
|
|
pub(crate) changed: Tick,
|
|
}
|
|
|
|
impl ComponentTicks {
|
|
/// Returns `true` if the component or resource was added after the system last ran
|
|
/// (or the system is running for the first time).
|
|
#[inline]
|
|
pub fn is_added(&self, last_run: Tick, this_run: Tick) -> bool {
|
|
self.added.is_newer_than(last_run, this_run)
|
|
}
|
|
|
|
/// Returns `true` if the component or resource was added or mutably dereferenced after the system last ran
|
|
/// (or the system is running for the first time).
|
|
#[inline]
|
|
pub fn is_changed(&self, last_run: Tick, this_run: Tick) -> bool {
|
|
self.changed.is_newer_than(last_run, this_run)
|
|
}
|
|
|
|
/// Returns the tick recording the time this component or resource was most recently changed.
|
|
#[inline]
|
|
pub fn last_changed_tick(&self) -> Tick {
|
|
self.changed
|
|
}
|
|
|
|
/// Returns the tick recording the time this component or resource was added.
|
|
#[inline]
|
|
pub fn added_tick(&self) -> Tick {
|
|
self.added
|
|
}
|
|
|
|
pub(crate) fn new(change_tick: Tick) -> Self {
|
|
Self {
|
|
added: change_tick,
|
|
changed: change_tick,
|
|
}
|
|
}
|
|
|
|
/// Manually sets the change tick.
|
|
///
|
|
/// This is normally done automatically via the [`DerefMut`](std::ops::DerefMut) implementation
|
|
/// on [`Mut<T>`](crate::change_detection::Mut), [`ResMut<T>`](crate::change_detection::ResMut), etc.
|
|
/// However, components and resources that make use of interior mutability might require manual updates.
|
|
///
|
|
/// # Example
|
|
/// ```no_run
|
|
/// # use bevy_ecs::{world::World, component::ComponentTicks};
|
|
/// let world: World = unimplemented!();
|
|
/// let component_ticks: ComponentTicks = unimplemented!();
|
|
///
|
|
/// component_ticks.set_changed(world.read_change_tick());
|
|
/// ```
|
|
#[inline]
|
|
pub fn set_changed(&mut self, change_tick: Tick) {
|
|
self.changed = change_tick;
|
|
}
|
|
}
|
|
|
|
/// A [`SystemParam`] that provides access to the [`ComponentId`] for a specific component type.
|
|
///
|
|
/// # Example
|
|
/// ```
|
|
/// # use bevy_ecs::{system::Local, component::{Component, ComponentId, ComponentIdFor}};
|
|
/// #[derive(Component)]
|
|
/// struct Player;
|
|
/// fn my_system(component_id: ComponentIdFor<Player>) {
|
|
/// let component_id: ComponentId = component_id.get();
|
|
/// // ...
|
|
/// }
|
|
/// ```
|
|
#[derive(SystemParam)]
|
|
pub struct ComponentIdFor<'s, T: Component>(Local<'s, InitComponentId<T>>);
|
|
|
|
impl<T: Component> ComponentIdFor<'_, T> {
|
|
/// Gets the [`ComponentId`] for the type `T`.
|
|
#[inline]
|
|
pub fn get(&self) -> ComponentId {
|
|
**self
|
|
}
|
|
}
|
|
|
|
impl<T: Component> core::ops::Deref for ComponentIdFor<'_, T> {
|
|
type Target = ComponentId;
|
|
fn deref(&self) -> &Self::Target {
|
|
&self.0.component_id
|
|
}
|
|
}
|
|
|
|
impl<T: Component> From<ComponentIdFor<'_, T>> for ComponentId {
|
|
#[inline]
|
|
fn from(to_component_id: ComponentIdFor<T>) -> ComponentId {
|
|
*to_component_id
|
|
}
|
|
}
|
|
|
|
/// Initializes the [`ComponentId`] for a specific type when used with [`FromWorld`].
|
|
struct InitComponentId<T: Component> {
|
|
component_id: ComponentId,
|
|
marker: PhantomData<T>,
|
|
}
|
|
|
|
impl<T: Component> FromWorld for InitComponentId<T> {
|
|
fn from_world(world: &mut World) -> Self {
|
|
Self {
|
|
component_id: world.register_component::<T>(),
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
}
|
|
|
|
/// An error returned when the registration of a required component fails.
|
|
#[derive(Error, Display, Debug)]
|
|
#[non_exhaustive]
|
|
pub enum RequiredComponentsError {
|
|
/// The component is already a directly required component for the requiree.
|
|
#[display("Component {0:?} already directly requires component {_1:?}")]
|
|
#[error(ignore)]
|
|
DuplicateRegistration(ComponentId, ComponentId),
|
|
/// An archetype with the component that requires other components already exists
|
|
#[display(
|
|
"An archetype with the component {_0:?} that requires other components already exists"
|
|
)]
|
|
#[error(ignore)]
|
|
ArchetypeExists(ComponentId),
|
|
}
|
|
|
|
/// A Required Component constructor. See [`Component`] for details.
|
|
#[cfg(feature = "track_change_detection")]
|
|
#[derive(Clone)]
|
|
pub struct RequiredComponentConstructor(
|
|
pub Arc<dyn Fn(&mut Table, &mut SparseSets, Tick, TableRow, Entity, &'static Location<'static>)>,
|
|
);
|
|
|
|
/// A Required Component constructor. See [`Component`] for details.
|
|
#[cfg(not(feature = "track_change_detection"))]
|
|
#[derive(Clone)]
|
|
pub struct RequiredComponentConstructor(
|
|
pub Arc<dyn Fn(&mut Table, &mut SparseSets, Tick, TableRow, Entity)>,
|
|
);
|
|
|
|
impl RequiredComponentConstructor {
|
|
/// # Safety
|
|
/// This is intended to only be called in the context of [`BundleInfo::write_components`] to initialized required components.
|
|
/// Calling it _anywhere else_ should be considered unsafe.
|
|
///
|
|
/// `table_row` and `entity` must correspond to a valid entity that currently needs a component initialized via the constructor stored
|
|
/// on this [`RequiredComponentConstructor`]. The stored constructor must correspond to a component on `entity` that needs initialization.
|
|
/// `table` and `sparse_sets` must correspond to storages on a world where `entity` needs this required component initialized.
|
|
///
|
|
/// Again, don't call this anywhere but [`BundleInfo::write_components`].
|
|
pub(crate) unsafe fn initialize(
|
|
&self,
|
|
table: &mut Table,
|
|
sparse_sets: &mut SparseSets,
|
|
change_tick: Tick,
|
|
table_row: TableRow,
|
|
entity: Entity,
|
|
#[cfg(feature = "track_change_detection")] caller: &'static Location<'static>,
|
|
) {
|
|
(self.0)(
|
|
table,
|
|
sparse_sets,
|
|
change_tick,
|
|
table_row,
|
|
entity,
|
|
#[cfg(feature = "track_change_detection")]
|
|
caller,
|
|
);
|
|
}
|
|
}
|
|
|
|
/// Metadata associated with a required component. See [`Component`] for details.
|
|
#[derive(Clone)]
|
|
pub struct RequiredComponent {
|
|
/// The constructor used for the required component.
|
|
pub constructor: RequiredComponentConstructor,
|
|
|
|
/// The depth of the component requirement in the requirement hierarchy for this component.
|
|
/// This is used for determining which constructor is used in cases where there are duplicate requires.
|
|
///
|
|
/// For example, consider the inheritance tree `X -> Y -> Z`, where `->` indicates a requirement.
|
|
/// `X -> Y` and `Y -> Z` are direct requirements with a depth of 0, while `Z` is only indirectly
|
|
/// required for `X` with a depth of `1`.
|
|
///
|
|
/// In cases where there are multiple conflicting requirements with the same depth, a higher priority
|
|
/// will be given to components listed earlier in the `require` attribute, or to the latest added requirement
|
|
/// if registered at runtime.
|
|
pub inheritance_depth: u16,
|
|
}
|
|
|
|
/// The collection of metadata for components that are required for a given component.
|
|
///
|
|
/// For more information, see the "Required Components" section of [`Component`].
|
|
#[derive(Default, Clone)]
|
|
pub struct RequiredComponents(pub(crate) HashMap<ComponentId, RequiredComponent>);
|
|
|
|
impl Debug for RequiredComponents {
|
|
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
|
|
f.debug_tuple("RequiredComponents")
|
|
.field(&self.0.keys())
|
|
.finish()
|
|
}
|
|
}
|
|
|
|
impl RequiredComponents {
|
|
/// Registers a required component.
|
|
///
|
|
/// If the component is already registered, it will be overwritten if the given inheritance depth
|
|
/// is smaller than the depth of the existing registration. Otherwise, the new registration will be ignored.
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// `component_id` must match the type initialized by `constructor`.
|
|
/// `constructor` _must_ initialize a component for `component_id` in such a way that
|
|
/// matches the storage type of the component. It must only use the given `table_row` or `Entity` to
|
|
/// initialize the storage for `component_id` corresponding to the given entity.
|
|
pub unsafe fn register_dynamic(
|
|
&mut self,
|
|
component_id: ComponentId,
|
|
constructor: RequiredComponentConstructor,
|
|
inheritance_depth: u16,
|
|
) {
|
|
self.0
|
|
.entry(component_id)
|
|
.and_modify(|component| {
|
|
if component.inheritance_depth > inheritance_depth {
|
|
// New registration is more specific than existing requirement
|
|
component.constructor = constructor.clone();
|
|
component.inheritance_depth = inheritance_depth;
|
|
}
|
|
})
|
|
.or_insert(RequiredComponent {
|
|
constructor,
|
|
inheritance_depth,
|
|
});
|
|
}
|
|
|
|
/// Registers a required component.
|
|
///
|
|
/// If the component is already registered, it will be overwritten if the given inheritance depth
|
|
/// is smaller than the depth of the existing registration. Otherwise, the new registration will be ignored.
|
|
pub fn register<C: Component>(
|
|
&mut self,
|
|
components: &mut Components,
|
|
storages: &mut Storages,
|
|
constructor: fn() -> C,
|
|
inheritance_depth: u16,
|
|
) {
|
|
let component_id = components.register_component::<C>(storages);
|
|
self.register_by_id(component_id, constructor, inheritance_depth);
|
|
}
|
|
|
|
/// Registers the [`Component`] with the given ID as required if it exists.
|
|
///
|
|
/// If the component is already registered, it will be overwritten if the given inheritance depth
|
|
/// is smaller than the depth of the existing registration. Otherwise, the new registration will be ignored.
|
|
pub fn register_by_id<C: Component>(
|
|
&mut self,
|
|
component_id: ComponentId,
|
|
constructor: fn() -> C,
|
|
inheritance_depth: u16,
|
|
) {
|
|
let erased: RequiredComponentConstructor = RequiredComponentConstructor(Arc::new(
|
|
move |table,
|
|
sparse_sets,
|
|
change_tick,
|
|
table_row,
|
|
entity,
|
|
#[cfg(feature = "track_change_detection")] caller| {
|
|
OwningPtr::make(constructor(), |ptr| {
|
|
// SAFETY: This will only be called in the context of `BundleInfo::write_components`, which will
|
|
// pass in a valid table_row and entity requiring a C constructor
|
|
// C::STORAGE_TYPE is the storage type associated with `component_id` / `C`
|
|
// `ptr` points to valid `C` data, which matches the type associated with `component_id`
|
|
unsafe {
|
|
BundleInfo::initialize_required_component(
|
|
table,
|
|
sparse_sets,
|
|
change_tick,
|
|
table_row,
|
|
entity,
|
|
component_id,
|
|
C::STORAGE_TYPE,
|
|
ptr,
|
|
#[cfg(feature = "track_change_detection")]
|
|
caller,
|
|
);
|
|
}
|
|
});
|
|
},
|
|
));
|
|
// SAFETY:
|
|
// `component_id` matches the type initialized by the `erased` constructor above.
|
|
// `erased` initializes a component for `component_id` in such a way that
|
|
// matches the storage type of the component. It only uses the given `table_row` or `Entity` to
|
|
// initialize the storage corresponding to the given entity.
|
|
unsafe { self.register_dynamic(component_id, erased, inheritance_depth) };
|
|
}
|
|
|
|
/// Iterates the ids of all required components. This includes recursive required components.
|
|
pub fn iter_ids(&self) -> impl Iterator<Item = ComponentId> + '_ {
|
|
self.0.keys().copied()
|
|
}
|
|
|
|
/// Removes components that are explicitly provided in a given [`Bundle`]. These components should
|
|
/// be logically treated as normal components, not "required components".
|
|
///
|
|
/// [`Bundle`]: crate::bundle::Bundle
|
|
pub(crate) fn remove_explicit_components(&mut self, components: &[ComponentId]) {
|
|
for component in components {
|
|
self.0.remove(component);
|
|
}
|
|
}
|
|
|
|
// Merges `required_components` into this collection. This only inserts a required component
|
|
// if it _did not already exist_.
|
|
pub(crate) fn merge(&mut self, required_components: &RequiredComponents) {
|
|
for (id, constructor) in &required_components.0 {
|
|
self.0.entry(*id).or_insert_with(|| constructor.clone());
|
|
}
|
|
}
|
|
}
|