974 lines
33 KiB
Rust
974 lines
33 KiB
Rust
//! Types for declaring and storing [`Component`]s.
|
|
|
|
use crate::{
|
|
self as bevy_ecs,
|
|
archetype::ArchetypeFlags,
|
|
change_detection::MAX_CHANGE_AGE,
|
|
entity::Entity,
|
|
storage::{SparseSetIndex, Storages},
|
|
system::{Local, Resource, SystemParam},
|
|
world::{DeferredWorld, FromWorld, World},
|
|
};
|
|
pub use bevy_ecs_macros::Component;
|
|
use bevy_ptr::{OwningPtr, UnsafeCellDeref};
|
|
#[cfg(feature = "bevy_reflect")]
|
|
use bevy_reflect::Reflect;
|
|
use bevy_utils::TypeIdMap;
|
|
use std::cell::UnsafeCell;
|
|
use std::{
|
|
alloc::Layout,
|
|
any::{Any, TypeId},
|
|
borrow::Cow,
|
|
marker::PhantomData,
|
|
mem::needs_drop,
|
|
};
|
|
|
|
/// A data type that can be used to store data for an [entity].
|
|
///
|
|
/// `Component` is a [derivable trait]: this means that a data type can implement it by applying a `#[derive(Component)]` attribute to it.
|
|
/// However, components must always satisfy the `Send + Sync + 'static` trait bounds.
|
|
///
|
|
/// [entity]: crate::entity
|
|
/// [derivable trait]: https://doc.rust-lang.org/book/appendix-03-derivable-traits.html
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// 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.
|
|
/// The following examples show how components are laid out in code.
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::component::Component;
|
|
/// # struct Color;
|
|
/// #
|
|
/// // A component can contain data...
|
|
/// #[derive(Component)]
|
|
/// struct LicensePlate(String);
|
|
///
|
|
/// // ... but it can also be a zero-sized marker.
|
|
/// #[derive(Component)]
|
|
/// struct Car;
|
|
///
|
|
/// // Components can also be structs with named fields...
|
|
/// #[derive(Component)]
|
|
/// struct VehiclePerformance {
|
|
/// acceleration: f32,
|
|
/// top_speed: f32,
|
|
/// handling: f32,
|
|
/// }
|
|
///
|
|
/// // ... or enums.
|
|
/// #[derive(Component)]
|
|
/// enum WheelCount {
|
|
/// Two,
|
|
/// Three,
|
|
/// Four,
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// # Component and data access
|
|
///
|
|
/// See the [`entity`] module level documentation to learn how to add or remove components from an entity.
|
|
///
|
|
/// See the documentation for [`Query`] to learn how to access component data from a system.
|
|
///
|
|
/// [`entity`]: crate::entity#usage
|
|
/// [`Query`]: crate::system::Query
|
|
///
|
|
/// # Choosing a storage type
|
|
///
|
|
/// Components can be stored in the world using different strategies with their own performance implications.
|
|
/// By default, components are added to the [`Table`] storage, which is optimized for query iteration.
|
|
///
|
|
/// Alternatively, components can be added to the [`SparseSet`] storage, which is optimized for component insertion and removal.
|
|
/// This is achieved by adding an additional `#[component(storage = "SparseSet")]` attribute to the derive one:
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::component::Component;
|
|
/// #
|
|
/// #[derive(Component)]
|
|
/// #[component(storage = "SparseSet")]
|
|
/// struct ComponentA;
|
|
/// ```
|
|
///
|
|
/// [`Table`]: crate::storage::Table
|
|
/// [`SparseSet`]: crate::storage::SparseSet
|
|
///
|
|
/// # Implementing the trait for foreign types
|
|
///
|
|
/// 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.
|
|
/// This means that it is not possible to directly have a type defined in a third party library as a component.
|
|
/// This important limitation can be easily worked around using the [newtype pattern]:
|
|
/// this makes it possible to locally define and implement `Component` for a tuple struct that wraps the foreign type.
|
|
/// The following example gives a demonstration of this pattern.
|
|
///
|
|
/// ```
|
|
/// // `Component` is defined in the `bevy_ecs` crate.
|
|
/// use bevy_ecs::component::Component;
|
|
///
|
|
/// // `Duration` is defined in the `std` crate.
|
|
/// use std::time::Duration;
|
|
///
|
|
/// // It is not possible to implement `Component` for `Duration` from this position, as they are
|
|
/// // both foreign items, defined in an external crate. However, nothing prevents to define a new
|
|
/// // `Cooldown` type that wraps `Duration`. As `Cooldown` is defined in a local crate, it is
|
|
/// // possible to implement `Component` for it.
|
|
/// #[derive(Component)]
|
|
/// struct Cooldown(Duration);
|
|
/// ```
|
|
///
|
|
/// [orphan rule]: https://doc.rust-lang.org/book/ch10-02-traits.html#implementing-a-trait-on-a-type
|
|
/// [newtype pattern]: https://doc.rust-lang.org/book/ch19-03-advanced-traits.html#using-the-newtype-pattern-to-implement-external-traits-on-external-types
|
|
///
|
|
/// # `!Sync` Components
|
|
/// A `!Sync` type cannot implement `Component`. However, it is possible to wrap a `Send` but not `Sync`
|
|
/// type in [`SyncCell`] or the currently unstable [`Exclusive`] to make it `Sync`. This forces only
|
|
/// having mutable access (`&mut T` only, never `&T`), but makes it safe to reference across multiple
|
|
/// threads.
|
|
///
|
|
/// This will fail to compile since `RefCell` is `!Sync`.
|
|
/// ```compile_fail
|
|
/// # use std::cell::RefCell;
|
|
/// # use bevy_ecs::component::Component;
|
|
/// #[derive(Component)]
|
|
/// struct NotSync {
|
|
/// counter: RefCell<usize>,
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// This will compile since the `RefCell` is wrapped with `SyncCell`.
|
|
/// ```
|
|
/// # use std::cell::RefCell;
|
|
/// # use bevy_ecs::component::Component;
|
|
/// use bevy_utils::synccell::SyncCell;
|
|
///
|
|
/// // This will compile.
|
|
/// #[derive(Component)]
|
|
/// struct ActuallySync {
|
|
/// counter: SyncCell<RefCell<usize>>,
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// [`SyncCell`]: bevy_utils::synccell::SyncCell
|
|
/// [`Exclusive`]: https://doc.rust-lang.org/nightly/std/sync/struct.Exclusive.html
|
|
pub trait Component: Send + Sync + 'static {
|
|
/// A constant indicating the storage type used for this component.
|
|
const STORAGE_TYPE: StorageType;
|
|
|
|
/// Called when registering this component, allowing mutable access to its [`ComponentHooks`].
|
|
fn register_component_hooks(_hooks: &mut ComponentHooks) {}
|
|
}
|
|
|
|
/// The storage used for a specific component type.
|
|
///
|
|
/// # Examples
|
|
/// The [`StorageType`] for a component is configured via the derive attribute
|
|
///
|
|
/// ```
|
|
/// # use bevy_ecs::{prelude::*, component::*};
|
|
/// #[derive(Component)]
|
|
/// #[component(storage = "SparseSet")]
|
|
/// struct A;
|
|
/// ```
|
|
#[derive(Debug, Copy, Clone, Default, Eq, PartialEq)]
|
|
pub enum StorageType {
|
|
/// Provides fast and cache-friendly iteration, but slower addition and removal of components.
|
|
/// This is the default storage type.
|
|
#[default]
|
|
Table,
|
|
/// Provides fast addition and removal of components, but slower iteration.
|
|
SparseSet,
|
|
}
|
|
|
|
/// The type used for [`Component`] lifecycle hooks such as `on_add`, `on_insert` or `on_remove`
|
|
pub type ComponentHook = for<'w> fn(DeferredWorld<'w>, Entity, ComponentId);
|
|
|
|
/// Lifecycle hooks for a given [`Component`], stored in its [`ComponentInfo`]
|
|
#[derive(Debug, Clone, Default)]
|
|
pub struct ComponentHooks {
|
|
pub(crate) on_add: Option<ComponentHook>,
|
|
pub(crate) on_insert: 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.
|
|
///
|
|
/// 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. The hook won't run if the component is already present and is only mutated.
|
|
/// An `on_insert` hook always runs after any `on_add` hooks (if the entity didn't already have the component).
|
|
///
|
|
/// 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 removed from an entity.
|
|
/// Despawning an entity counts as removing all of its components.
|
|
///
|
|
/// 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")
|
|
}
|
|
|
|
/// 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)
|
|
}
|
|
|
|
/// 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)
|
|
}
|
|
|
|
/// 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,
|
|
}
|
|
|
|
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: ComponentHooks::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_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
|
|
}
|
|
}
|
|
|
|
/// A value which uniquely identifies the type of a [`Component`] of [`Resource`] within a
|
|
/// [`World`].
|
|
///
|
|
/// Each time a new `Component` type is registered within a `World` using
|
|
/// e.g. [`World::init_component`] or [`World::init_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 std::fmt::Debug for ComponentDescriptor {
|
|
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::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 points 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(std::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(std::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(std::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 {
|
|
/// Initializes a component of type `T` with this instance.
|
|
/// If a component of this type has already been initialized, this will return
|
|
/// the ID of the pre-existing component.
|
|
///
|
|
/// # See also
|
|
///
|
|
/// * [`Components::component_id()`]
|
|
/// * [`Components::init_component_with_descriptor()`]
|
|
#[inline]
|
|
pub fn init_component<T: Component>(&mut self, storages: &mut Storages) -> ComponentId {
|
|
let type_id = TypeId::of::<T>();
|
|
|
|
let Components {
|
|
indices,
|
|
components,
|
|
..
|
|
} = self;
|
|
*indices.entry(type_id).or_insert_with(|| {
|
|
let index = Components::init_component_inner(
|
|
components,
|
|
storages,
|
|
ComponentDescriptor::new::<T>(),
|
|
);
|
|
T::register_component_hooks(&mut components[index.index()].hooks);
|
|
index
|
|
})
|
|
}
|
|
|
|
/// Initializes 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::init_component()`]
|
|
pub fn init_component_with_descriptor(
|
|
&mut self,
|
|
storages: &mut Storages,
|
|
descriptor: ComponentDescriptor,
|
|
) -> ComponentId {
|
|
Components::init_component_inner(&mut self.components, storages, descriptor)
|
|
}
|
|
|
|
#[inline]
|
|
fn init_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(|descriptor| descriptor.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)
|
|
}
|
|
|
|
/// 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::init_component()`].
|
|
///
|
|
/// ```
|
|
/// use bevy_ecs::prelude::*;
|
|
///
|
|
/// let mut world = World::new();
|
|
///
|
|
/// #[derive(Component)]
|
|
/// struct ComponentA;
|
|
///
|
|
/// let component_a_id = world.init_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::init_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>())
|
|
}
|
|
|
|
/// Initializes a [`Resource`] of type `T` with this instance.
|
|
/// If a resource of this type has already been initialized, this will return
|
|
/// the ID of the pre-existing resource.
|
|
///
|
|
/// # See also
|
|
///
|
|
/// * [`Components::resource_id()`]
|
|
#[inline]
|
|
pub fn init_resource<T: Resource>(&mut self) -> ComponentId {
|
|
// SAFETY: The [`ComponentDescriptor`] matches the [`TypeId`]
|
|
unsafe {
|
|
self.get_or_insert_resource_with(TypeId::of::<T>(), || {
|
|
ComponentDescriptor::new_resource::<T>()
|
|
})
|
|
}
|
|
}
|
|
|
|
/// Initializes a [non-send resource](crate::system::NonSend) of type `T` with this instance.
|
|
/// If a resource of this type has already been initialized, this will return
|
|
/// the ID of the pre-existing resource.
|
|
#[inline]
|
|
pub fn init_non_send<T: Any>(&mut self) -> ComponentId {
|
|
// SAFETY: The [`ComponentDescriptor`] matches the [`TypeId`]
|
|
unsafe {
|
|
self.get_or_insert_resource_with(TypeId::of::<T>(), || {
|
|
ComponentDescriptor::new_non_send::<T>(StorageType::default())
|
|
})
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// The [`ComponentDescriptor`] must match the [`TypeId`]
|
|
#[inline]
|
|
unsafe fn get_or_insert_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();
|
|
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.
|
|
#[derive(Copy, Clone, Default, Debug, Eq, PartialEq)]
|
|
#[cfg_attr(feature = "bevy_reflect", derive(Reflect), reflect(Debug, 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.
|
|
#[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.
|
|
#[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> std::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.init_component::<T>(),
|
|
marker: PhantomData,
|
|
}
|
|
}
|
|
}
|