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fetch.rs
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fetch.rs
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use crate::{
archetype::{Archetype, ArchetypeComponentId},
change_detection::{Ticks, TicksMut},
component::{Component, ComponentId, ComponentStorage, StorageType, Tick},
entity::Entity,
query::{Access, DebugCheckedUnwrap, FilteredAccess},
storage::{ComponentSparseSet, Table, TableRow},
world::{unsafe_world_cell::UnsafeWorldCell, EntityMut, EntityRef, Mut, Ref, World},
};
pub use bevy_ecs_macros::WorldQuery;
use bevy_ptr::{ThinSlicePtr, UnsafeCellDeref};
use bevy_utils::all_tuples;
use std::{cell::UnsafeCell, marker::PhantomData};
/// Types that can be fetched from a [`World`] using a [`Query`].
///
/// There are many types that natively implement this trait:
///
/// - **Component references.**
/// Fetches a component by reference (immutably or mutably).
/// - **`WorldQuery` tuples.**
/// If every element of a tuple implements `WorldQuery`, then the tuple itself also implements the same trait.
/// This enables a single `Query` to access multiple components and filter over multiple conditions.
/// Due to the current lack of variadic generics in Rust, the trait has been implemented for tuples from 0 to 15 elements,
/// but nesting of tuples allows infinite `WorldQuery`s.
/// - **Component filters.**
/// [`With`] and [`Without`] filters can be applied to check if the queried entity contains or not a particular component.
/// - **Change detection filters.**
/// [`Added`] and [`Changed`] filters can be applied to detect component changes to an entity.
/// - **Filter disjunction operator.**
/// By default, tuples compose query filters in such a way that all conditions must be satisfied to generate a query item for a given entity.
/// Wrapping a tuple inside an [`Or`] operator will relax the requirement to just one condition.
/// - **[`Entity`].**
/// Gets the identifier of the queried entity.
/// - **[`Option`].**
/// By default, a world query only tests entities that have the matching component types.
/// Wrapping it into an `Option` will increase the query search space, and it will return `None` if an entity doesn't satisfy the `WorldQuery`.
/// - **[`AnyOf`].**
/// Equivalent to wrapping each world query inside it into an `Option`.
/// - **[`Ref`].**
/// Similar to change detection filters but it is used as a query fetch parameter.
/// It exposes methods to check for changes to the wrapped component.
///
/// Implementing the trait manually can allow for a fundamentally new type of behavior.
///
/// # Trait derivation
///
/// Query design can be easily structured by deriving `WorldQuery` for custom types.
/// Despite the added complexity, this approach has several advantages over using `WorldQuery` tuples.
/// The most relevant improvements are:
///
/// - Reusability across multiple systems.
/// - There is no need to destructure a tuple since all fields are named.
/// - Subqueries can be composed together to create a more complex query.
/// - Methods can be implemented for the query items.
/// - There is no hardcoded limit on the number of elements.
///
/// This trait can only be derived for structs, if each field also implements `WorldQuery`.
///
/// ```
/// # use bevy_ecs::prelude::*;
/// use bevy_ecs::query::WorldQuery;
/// #
/// # #[derive(Component)]
/// # struct ComponentA;
/// # #[derive(Component)]
/// # struct ComponentB;
///
/// #[derive(WorldQuery)]
/// struct MyQuery {
/// entity: Entity,
/// // It is required that all reference lifetimes are explicitly annotated, just like in any
/// // struct. Each lifetime should be 'static.
/// component_a: &'static ComponentA,
/// component_b: &'static ComponentB,
/// }
///
/// fn my_system(query: Query<MyQuery>) {
/// for q in &query {
/// q.component_a;
/// }
/// }
/// # bevy_ecs::system::assert_is_system(my_system);
/// ```
///
/// ## Macro expansion
///
/// Expanding the macro will declare one or three additional structs, depending on whether or not the struct is marked as mutable.
/// For a struct named `X`, the additional structs will be:
///
/// |Struct name|`mutable` only|Description|
/// |:---:|:---:|---|
/// |`XItem`|---|The type of the query item for `X`|
/// |`XReadOnlyItem`|✓|The type of the query item for `XReadOnly`|
/// |`XReadOnly`|✓|[`ReadOnly`] variant of `X`|
///
/// ## Adding mutable references
///
/// Simply adding mutable references to a derived `WorldQuery` will result in a compilation error:
///
/// ```compile_fail
/// # use bevy_ecs::prelude::*;
/// # use bevy_ecs::query::WorldQuery;
/// #
/// # #[derive(Component)]
/// # struct ComponentA;
/// #
/// #[derive(WorldQuery)]
/// struct CustomQuery {
/// component_a: &'static mut ComponentA,
/// }
/// ```
///
/// To grant mutable access to components, the struct must be marked with the `#[world_query(mutable)]` attribute.
/// This will also create three more structs that will be used for accessing the query immutably (see table above).
///
/// ```
/// # use bevy_ecs::prelude::*;
/// # use bevy_ecs::query::WorldQuery;
/// #
/// # #[derive(Component)]
/// # struct ComponentA;
/// #
/// #[derive(WorldQuery)]
/// #[world_query(mutable)]
/// struct CustomQuery {
/// component_a: &'static mut ComponentA,
/// }
/// ```
///
/// ## Adding methods to query items
///
/// It is possible to add methods to query items in order to write reusable logic about related components.
/// This will often make systems more readable because low level logic is moved out from them.
/// It is done by adding `impl` blocks with methods for the `-Item` or `-ReadOnlyItem` generated structs.
///
/// ```
/// # use bevy_ecs::prelude::*;
/// # use bevy_ecs::query::WorldQuery;
/// #
/// #[derive(Component)]
/// struct Health(f32);
///
/// #[derive(Component)]
/// struct Buff(f32);
///
/// #[derive(WorldQuery)]
/// #[world_query(mutable)]
/// struct HealthQuery {
/// health: &'static mut Health,
/// buff: Option<&'static mut Buff>,
/// }
///
/// // `HealthQueryItem` is only available when accessing the query with mutable methods.
/// impl<'w> HealthQueryItem<'w> {
/// fn damage(&mut self, value: f32) {
/// self.health.0 -= value;
/// }
///
/// fn total(&self) -> f32 {
/// self.health.0 + self.buff.as_deref().map_or(0.0, |Buff(buff)| *buff)
/// }
/// }
///
/// // `HealthQueryReadOnlyItem` is only available when accessing the query with immutable methods.
/// impl<'w> HealthQueryReadOnlyItem<'w> {
/// fn total(&self) -> f32 {
/// self.health.0 + self.buff.map_or(0.0, |Buff(buff)| *buff)
/// }
/// }
///
/// fn my_system(mut health_query: Query<HealthQuery>) {
/// // The item returned by the iterator is of type `HealthQueryReadOnlyItem`.
/// for health in health_query.iter() {
/// println!("Total: {}", health.total());
/// }
/// // The item returned by the iterator is of type `HealthQueryItem`.
/// for mut health in &mut health_query {
/// health.damage(1.0);
/// println!("Total (mut): {}", health.total());
/// }
/// }
/// # bevy_ecs::system::assert_is_system(my_system);
/// ```
///
/// ## Deriving traits for query items
///
/// The `WorldQuery` derive macro does not automatically implement the traits of the struct to the query item types.
/// Something similar can be done by using the `#[world_query(derive(...))]` attribute.
/// This will apply the listed derivable traits to the query item structs.
///
/// ```
/// # use bevy_ecs::prelude::*;
/// # use bevy_ecs::query::WorldQuery;
/// #
/// # #[derive(Component, Debug)]
/// # struct ComponentA;
/// #
/// #[derive(WorldQuery)]
/// #[world_query(mutable, derive(Debug))]
/// struct CustomQuery {
/// component_a: &'static ComponentA,
/// }
///
/// // This function statically checks that `T` implements `Debug`.
/// fn assert_debug<T: std::fmt::Debug>() {}
///
/// assert_debug::<CustomQueryItem>();
/// assert_debug::<CustomQueryReadOnlyItem>();
/// ```
///
/// ## Query composition
///
/// It is possible to use any `WorldQuery` as a field of another one.
/// This means that a `WorldQuery` can also be used as a subquery, potentially in multiple places.
///
/// ```
/// # use bevy_ecs::prelude::*;
/// # use bevy_ecs::query::WorldQuery;
/// #
/// # #[derive(Component)]
/// # struct ComponentA;
/// # #[derive(Component)]
/// # struct ComponentB;
/// # #[derive(Component)]
/// # struct ComponentC;
/// #
/// #[derive(WorldQuery)]
/// struct SubQuery {
/// component_a: &'static ComponentA,
/// component_b: &'static ComponentB,
/// }
///
/// #[derive(WorldQuery)]
/// struct MyQuery {
/// subquery: SubQuery,
/// component_c: &'static ComponentC,
/// }
/// ```
///
/// ## Filters
///
/// Since the query filter type parameter is `WorldQuery`, it is also possible to use this macro to create filters.
///
/// ```
/// # use bevy_ecs::prelude::*;
/// # use bevy_ecs::{query::WorldQuery, component::Component};
/// #
/// # #[derive(Component)]
/// # struct ComponentA;
/// # #[derive(Component)]
/// # struct ComponentB;
/// # #[derive(Component)]
/// # struct ComponentC;
/// # #[derive(Component)]
/// # struct ComponentD;
/// # #[derive(Component)]
/// # struct ComponentE;
/// #
/// #[derive(WorldQuery)]
/// struct MyFilter<T: Component, P: Component> {
/// // Field names are not relevant, since they are never manually accessed.
/// with_a: With<ComponentA>,
/// or_filter: Or<(With<ComponentC>, Added<ComponentB>)>,
/// generic_tuple: (With<T>, Without<P>),
/// }
///
/// fn my_system(query: Query<Entity, MyFilter<ComponentD, ComponentE>>) {
/// // ...
/// }
/// # bevy_ecs::system::assert_is_system(my_system);
/// ```
///
/// # Generic Queries
///
/// When writing generic code, it is often necessary to use [`PhantomData`]
/// to constrain type parameters. Since `WorldQuery` is implemented for all
/// `PhantomData<T>` types, this pattern can be used with this macro.
///
/// ```
/// # use bevy_ecs::{prelude::*, query::WorldQuery};
/// # use std::marker::PhantomData;
/// #[derive(WorldQuery)]
/// pub struct GenericQuery<T> {
/// id: Entity,
/// marker: PhantomData<T>,
/// }
/// # fn my_system(q: Query<GenericQuery<()>>) {}
/// # bevy_ecs::system::assert_is_system(my_system);
/// ```
///
/// # Safety
///
/// Component access of `Self::ReadOnly` must be a subset of `Self`
/// and `Self::ReadOnly` must match exactly the same archetypes/tables as `Self`
///
/// Implementor must ensure that
/// [`update_component_access`] and [`update_archetype_component_access`]
/// exactly reflects the results of the following methods:
///
/// - [`matches_component_set`]
/// - [`fetch`]
///
/// [`Added`]: crate::query::Added
/// [`fetch`]: Self::fetch
/// [`Changed`]: crate::query::Changed
/// [`matches_component_set`]: Self::matches_component_set
/// [`Or`]: crate::query::Or
/// [`Query`]: crate::system::Query
/// [`ReadOnly`]: Self::ReadOnly
/// [`State`]: Self::State
/// [`update_archetype_component_access`]: Self::update_archetype_component_access
/// [`update_component_access`]: Self::update_component_access
/// [`With`]: crate::query::With
/// [`Without`]: crate::query::Without
pub unsafe trait WorldQuery {
/// The item returned by this [`WorldQuery`]
type Item<'a>;
/// Per archetype/table state used by this [`WorldQuery`] to fetch [`Self::Item`](crate::query::WorldQuery::Item)
type Fetch<'a>: Clone;
/// The read-only variant of this [`WorldQuery`], which satisfies the [`ReadOnlyWorldQuery`] trait.
type ReadOnly: ReadOnlyWorldQuery<State = Self::State>;
/// State used to construct a [`Self::Fetch`](crate::query::WorldQuery::Fetch). This will be cached inside [`QueryState`](crate::query::QueryState),
/// so it is best to move as much data / computation here as possible to reduce the cost of
/// constructing [`Self::Fetch`](crate::query::WorldQuery::Fetch).
type State: Send + Sync + Sized;
/// This function manually implements subtyping for the query items.
fn shrink<'wlong: 'wshort, 'wshort>(item: Self::Item<'wlong>) -> Self::Item<'wshort>;
/// Creates a new instance of this fetch.
///
/// # Safety
///
/// - `world` must have permission to access any of the components specified in `Self::update_archetype_component_access`.
/// - `state` must have been initialized (via [`WorldQuery::init_state`]) using the same `world` passed
/// in to this function.
unsafe fn init_fetch<'w>(
world: UnsafeWorldCell<'w>,
state: &Self::State,
last_run: Tick,
this_run: Tick,
) -> Self::Fetch<'w>;
/// Returns true if (and only if) every table of every archetype matched by this fetch contains
/// all of the matched components. This is used to select a more efficient "table iterator"
/// for "dense" queries. If this returns true, [`WorldQuery::set_table`] must be used before
/// [`WorldQuery::fetch`] can be called for iterators. If this returns false,
/// [`WorldQuery::set_archetype`] must be used before [`WorldQuery::fetch`] can be called for
/// iterators.
const IS_DENSE: bool;
/// Returns true if (and only if) this Fetch relies strictly on archetypes to limit which
/// components are accessed by the Query.
///
/// This enables optimizations for [`crate::query::QueryIter`] that rely on knowing exactly how
/// many elements are being iterated (such as `Iterator::collect()`).
const IS_ARCHETYPAL: bool;
/// Adjusts internal state to account for the next [`Archetype`]. This will always be called on
/// archetypes that match this [`WorldQuery`].
///
/// # Safety
///
/// - `archetype` and `tables` must be from the same [`World`] that [`WorldQuery::init_state`] was called on.
/// - [`Self::update_archetype_component_access`] must have been previously called with `archetype`.
/// - `table` must correspond to `archetype`.
/// - `state` must be the [`State`](Self::State) that `fetch` was initialized with.
unsafe fn set_archetype<'w>(
fetch: &mut Self::Fetch<'w>,
state: &Self::State,
archetype: &'w Archetype,
table: &'w Table,
);
/// Adjusts internal state to account for the next [`Table`]. This will always be called on tables
/// that match this [`WorldQuery`].
///
/// # Safety
///
/// - `table` must be from the same [`World`] that [`WorldQuery::init_state`] was called on.
/// - `table` must belong to an archetype that was previously registered with
/// [`Self::update_archetype_component_access`].
/// - `state` must be the [`State`](Self::State) that `fetch` was initialized with.
unsafe fn set_table<'w>(fetch: &mut Self::Fetch<'w>, state: &Self::State, table: &'w Table);
/// Fetch [`Self::Item`](`WorldQuery::Item`) for either the given `entity` in the current [`Table`],
/// or for the given `entity` in the current [`Archetype`]. This must always be called after
/// [`WorldQuery::set_table`] with a `table_row` in the range of the current [`Table`] or after
/// [`WorldQuery::set_archetype`] with a `entity` in the current archetype.
///
/// # Safety
///
/// Must always be called _after_ [`WorldQuery::set_table`] or [`WorldQuery::set_archetype`]. `entity` and
/// `table_row` must be in the range of the current table and archetype.
///
/// If `update_component_access` includes any mutable accesses, then the caller must ensure
/// that `fetch` is called no more than once for each `entity`/`table_row` in each archetype.
/// If `Self` implements [`ReadOnlyWorldQuery`], then this can safely be called multiple times.
unsafe fn fetch<'w>(
fetch: &mut Self::Fetch<'w>,
entity: Entity,
table_row: TableRow,
) -> Self::Item<'w>;
/// # Safety
///
/// Must always be called _after_ [`WorldQuery::set_table`] or [`WorldQuery::set_archetype`]. `entity` and
/// `table_row` must be in the range of the current table and archetype.
#[allow(unused_variables)]
#[inline(always)]
unsafe fn filter_fetch(
fetch: &mut Self::Fetch<'_>,
entity: Entity,
table_row: TableRow,
) -> bool {
true
}
/// Adds any component accesses used by this [`WorldQuery`] to `access`.
// This does not have a default body of `{}` because 99% of cases need to add accesses
// and forgetting to do so would be unsound.
fn update_component_access(state: &Self::State, access: &mut FilteredAccess<ComponentId>);
/// For the given `archetype`, adds any component accessed used by this [`WorldQuery`] to `access`.
// This does not have a default body of `{}` because 99% of cases need to add accesses
// and forgetting to do so would be unsound.
fn update_archetype_component_access(
state: &Self::State,
archetype: &Archetype,
access: &mut Access<ArchetypeComponentId>,
);
/// Creates and initializes a [`State`](WorldQuery::State) for this [`WorldQuery`] type.
fn init_state(world: &mut World) -> Self::State;
/// Returns `true` if this query matches a set of components. Otherwise, returns `false`.
fn matches_component_set(
state: &Self::State,
set_contains_id: &impl Fn(ComponentId) -> bool,
) -> bool;
}
/// A world query that is read only.
///
/// # Safety
///
/// This must only be implemented for read-only [`WorldQuery`]'s.
pub unsafe trait ReadOnlyWorldQuery: WorldQuery<ReadOnly = Self> {}
/// The item type returned when a [`WorldQuery`] is iterated over
pub type QueryItem<'w, Q> = <Q as WorldQuery>::Item<'w>;
/// The read-only variant of the item type returned when a [`WorldQuery`] is iterated over immutably
pub type ROQueryItem<'w, Q> = QueryItem<'w, <Q as WorldQuery>::ReadOnly>;
/// SAFETY: no component or archetype access
unsafe impl WorldQuery for Entity {
type Fetch<'w> = ();
type Item<'w> = Entity;
type ReadOnly = Self;
type State = ();
fn shrink<'wlong: 'wshort, 'wshort>(item: Self::Item<'wlong>) -> Self::Item<'wshort> {
item
}
const IS_DENSE: bool = true;
const IS_ARCHETYPAL: bool = true;
unsafe fn init_fetch<'w>(
_world: UnsafeWorldCell<'w>,
_state: &Self::State,
_last_run: Tick,
_this_run: Tick,
) -> Self::Fetch<'w> {
}
#[inline]
unsafe fn set_archetype<'w>(
_fetch: &mut Self::Fetch<'w>,
_state: &Self::State,
_archetype: &'w Archetype,
_table: &Table,
) {
}
#[inline]
unsafe fn set_table<'w>(_fetch: &mut Self::Fetch<'w>, _state: &Self::State, _table: &'w Table) {
}
#[inline(always)]
unsafe fn fetch<'w>(
_fetch: &mut Self::Fetch<'w>,
entity: Entity,
_table_row: TableRow,
) -> Self::Item<'w> {
entity
}
fn update_component_access(_state: &Self::State, _access: &mut FilteredAccess<ComponentId>) {}
fn update_archetype_component_access(
_state: &Self::State,
_archetype: &Archetype,
_access: &mut Access<ArchetypeComponentId>,
) {
}
fn init_state(_world: &mut World) {}
fn matches_component_set(
_state: &Self::State,
_set_contains_id: &impl Fn(ComponentId) -> bool,
) -> bool {
true
}
}
/// SAFETY: access is read only
unsafe impl ReadOnlyWorldQuery for Entity {}
/// SAFETY: `Self` is the same as `Self::ReadOnly`
unsafe impl WorldQuery for EntityRef<'_> {
type Fetch<'w> = UnsafeWorldCell<'w>;
type Item<'w> = EntityRef<'w>;
type ReadOnly = Self;
type State = ();
fn shrink<'wlong: 'wshort, 'wshort>(item: Self::Item<'wlong>) -> Self::Item<'wshort> {
item
}
const IS_DENSE: bool = true;
const IS_ARCHETYPAL: bool = true;
unsafe fn init_fetch<'w>(
world: UnsafeWorldCell<'w>,
_state: &Self::State,
_last_run: Tick,
_this_run: Tick,
) -> Self::Fetch<'w> {
world
}
#[inline]
unsafe fn set_archetype<'w>(
_fetch: &mut Self::Fetch<'w>,
_state: &Self::State,
_archetype: &'w Archetype,
_table: &Table,
) {
}
#[inline]
unsafe fn set_table<'w>(_fetch: &mut Self::Fetch<'w>, _state: &Self::State, _table: &'w Table) {
}
#[inline(always)]
unsafe fn fetch<'w>(
world: &mut Self::Fetch<'w>,
entity: Entity,
_table_row: TableRow,
) -> Self::Item<'w> {
// SAFETY: `fetch` must be called with an entity that exists in the world
let cell = world.get_entity(entity).debug_checked_unwrap();
// SAFETY: Read-only access to every component has been registered.
EntityRef::new(cell)
}
fn update_component_access(_state: &Self::State, access: &mut FilteredAccess<ComponentId>) {
assert!(
!access.access().has_any_write(),
"EntityRef conflicts with a previous access in this query. Shared access cannot coincide with exclusive access.",
);
access.read_all();
}
fn update_archetype_component_access(
_state: &Self::State,
archetype: &Archetype,
access: &mut Access<ArchetypeComponentId>,
) {
for component_id in archetype.components() {
access.add_read(archetype.get_archetype_component_id(component_id).unwrap());
}
}
fn init_state(_world: &mut World) {}
fn matches_component_set(
_state: &Self::State,
_set_contains_id: &impl Fn(ComponentId) -> bool,
) -> bool {
true
}
}
/// SAFETY: Access is read-only.
unsafe impl ReadOnlyWorldQuery for EntityRef<'_> {}
/// SAFETY: The accesses of `Self::ReadOnly` are a subset of the accesses of `Self`
unsafe impl<'a> WorldQuery for EntityMut<'a> {
type Fetch<'w> = UnsafeWorldCell<'w>;
type Item<'w> = EntityMut<'w>;
type ReadOnly = EntityRef<'a>;
type State = ();
fn shrink<'wlong: 'wshort, 'wshort>(item: Self::Item<'wlong>) -> Self::Item<'wshort> {
item
}
const IS_DENSE: bool = true;
const IS_ARCHETYPAL: bool = true;
unsafe fn init_fetch<'w>(
world: UnsafeWorldCell<'w>,
_state: &Self::State,
_last_run: Tick,
_this_run: Tick,
) -> Self::Fetch<'w> {
world
}
#[inline]
unsafe fn set_archetype<'w>(
_fetch: &mut Self::Fetch<'w>,
_state: &Self::State,
_archetype: &'w Archetype,
_table: &Table,
) {
}
#[inline]
unsafe fn set_table<'w>(_fetch: &mut Self::Fetch<'w>, _state: &Self::State, _table: &'w Table) {
}
#[inline(always)]
unsafe fn fetch<'w>(
world: &mut Self::Fetch<'w>,
entity: Entity,
_table_row: TableRow,
) -> Self::Item<'w> {
// SAFETY: `fetch` must be called with an entity that exists in the world
let cell = world.get_entity(entity).debug_checked_unwrap();
// SAFETY: mutable access to every component has been registered.
EntityMut::new(cell)
}
fn update_component_access(_state: &Self::State, access: &mut FilteredAccess<ComponentId>) {
assert!(
!access.access().has_any_read(),
"EntityMut conflicts with a previous access in this query. Exclusive access cannot coincide with any other accesses.",
);
access.write_all();
}
fn update_archetype_component_access(
_state: &Self::State,
archetype: &Archetype,
access: &mut Access<ArchetypeComponentId>,
) {
for component_id in archetype.components() {
access.add_write(archetype.get_archetype_component_id(component_id).unwrap());
}
}
fn init_state(_world: &mut World) {}
fn matches_component_set(
_state: &Self::State,
_set_contains_id: &impl Fn(ComponentId) -> bool,
) -> bool {
true
}
}
#[doc(hidden)]
pub struct ReadFetch<'w, T> {
// T::Storage = TableStorage
table_components: Option<ThinSlicePtr<'w, UnsafeCell<T>>>,
// T::Storage = SparseStorage
sparse_set: Option<&'w ComponentSparseSet>,
}
impl<T> Clone for ReadFetch<'_, T> {
fn clone(&self) -> Self {
*self
}
}
impl<T> Copy for ReadFetch<'_, T> {}
/// SAFETY: `Self` is the same as `Self::ReadOnly`
unsafe impl<T: Component> WorldQuery for &T {
type Fetch<'w> = ReadFetch<'w, T>;
type Item<'w> = &'w T;
type ReadOnly = Self;
type State = ComponentId;
fn shrink<'wlong: 'wshort, 'wshort>(item: &'wlong T) -> &'wshort T {
item
}
const IS_DENSE: bool = {
match T::Storage::STORAGE_TYPE {
StorageType::Table => true,
StorageType::SparseSet => false,
}
};
const IS_ARCHETYPAL: bool = true;
#[inline]
unsafe fn init_fetch<'w>(
world: UnsafeWorldCell<'w>,
&component_id: &ComponentId,
_last_run: Tick,
_this_run: Tick,
) -> ReadFetch<'w, T> {
ReadFetch {
table_components: None,
sparse_set: (T::Storage::STORAGE_TYPE == StorageType::SparseSet).then(|| {
world
// SAFETY: The underlying type associated with `component_id` is `T`,
// which we are allowed to access since we registered it in `update_archetype_component_access`.
// Note that we do not actually access any components in this function, we just get a shared
// reference to the sparse set, which is used to access the components in `Self::fetch`.
.storages()
.sparse_sets
.get(component_id)
.debug_checked_unwrap()
}),
}
}
#[inline]
unsafe fn set_archetype<'w>(
fetch: &mut ReadFetch<'w, T>,
component_id: &ComponentId,
_archetype: &'w Archetype,
table: &'w Table,
) {
if Self::IS_DENSE {
Self::set_table(fetch, component_id, table);
}
}
#[inline]
unsafe fn set_table<'w>(
fetch: &mut ReadFetch<'w, T>,
&component_id: &ComponentId,
table: &'w Table,
) {
fetch.table_components = Some(
table
.get_column(component_id)
.debug_checked_unwrap()
.get_data_slice()
.into(),
);
}
#[inline(always)]
unsafe fn fetch<'w>(
fetch: &mut Self::Fetch<'w>,
entity: Entity,
table_row: TableRow,
) -> Self::Item<'w> {
match T::Storage::STORAGE_TYPE {
StorageType::Table => fetch
.table_components
.debug_checked_unwrap()
.get(table_row.index())
.deref(),
StorageType::SparseSet => fetch
.sparse_set
.debug_checked_unwrap()
.get(entity)
.debug_checked_unwrap()
.deref(),
}
}
fn update_component_access(
&component_id: &ComponentId,
access: &mut FilteredAccess<ComponentId>,
) {
assert!(
!access.access().has_write(component_id),
"&{} conflicts with a previous access in this query. Shared access cannot coincide with exclusive access.",
std::any::type_name::<T>(),
);
access.add_read(component_id);
}
fn update_archetype_component_access(
&component_id: &ComponentId,
archetype: &Archetype,
access: &mut Access<ArchetypeComponentId>,
) {
if let Some(archetype_component_id) = archetype.get_archetype_component_id(component_id) {
access.add_read(archetype_component_id);
}
}
fn init_state(world: &mut World) -> ComponentId {
world.init_component::<T>()
}
fn matches_component_set(
&state: &ComponentId,
set_contains_id: &impl Fn(ComponentId) -> bool,
) -> bool {
set_contains_id(state)
}
}
/// SAFETY: access is read only
unsafe impl<T: Component> ReadOnlyWorldQuery for &T {}
#[doc(hidden)]
pub struct RefFetch<'w, T> {
// T::Storage = TableStorage
table_data: Option<(
ThinSlicePtr<'w, UnsafeCell<T>>,
ThinSlicePtr<'w, UnsafeCell<Tick>>,
ThinSlicePtr<'w, UnsafeCell<Tick>>,
)>,
// T::Storage = SparseStorage
sparse_set: Option<&'w ComponentSparseSet>,
last_run: Tick,
this_run: Tick,
}
impl<T> Clone for RefFetch<'_, T> {
fn clone(&self) -> Self {
*self
}
}
impl<T> Copy for RefFetch<'_, T> {}
/// SAFETY: `Self` is the same as `Self::ReadOnly`
unsafe impl<'__w, T: Component> WorldQuery for Ref<'__w, T> {
type Fetch<'w> = RefFetch<'w, T>;
type Item<'w> = Ref<'w, T>;
type ReadOnly = Self;
type State = ComponentId;
fn shrink<'wlong: 'wshort, 'wshort>(item: Ref<'wlong, T>) -> Ref<'wshort, T> {
item
}
const IS_DENSE: bool = {
match T::Storage::STORAGE_TYPE {
StorageType::Table => true,
StorageType::SparseSet => false,
}
};
const IS_ARCHETYPAL: bool = true;
#[inline]
unsafe fn init_fetch<'w>(
world: UnsafeWorldCell<'w>,
&component_id: &ComponentId,
last_run: Tick,
this_run: Tick,
) -> RefFetch<'w, T> {
RefFetch {
table_data: None,
sparse_set: (T::Storage::STORAGE_TYPE == StorageType::SparseSet).then(|| {
world
// SAFETY: See &T::init_fetch.
.storages()
.sparse_sets
.get(component_id)
.debug_checked_unwrap()
}),
last_run,
this_run,
}
}
#[inline]
unsafe fn set_archetype<'w>(
fetch: &mut RefFetch<'w, T>,
component_id: &ComponentId,
_archetype: &'w Archetype,
table: &'w Table,
) {
if Self::IS_DENSE {
Self::set_table(fetch, component_id, table);
}
}
#[inline]
unsafe fn set_table<'w>(
fetch: &mut RefFetch<'w, T>,
&component_id: &ComponentId,
table: &'w Table,
) {
let column = table.get_column(component_id).debug_checked_unwrap();
fetch.table_data = Some((
column.get_data_slice().into(),
column.get_added_ticks_slice().into(),
column.get_changed_ticks_slice().into(),
));
}
#[inline(always)]
unsafe fn fetch<'w>(
fetch: &mut Self::Fetch<'w>,
entity: Entity,
table_row: TableRow,
) -> Self::Item<'w> {
match T::Storage::STORAGE_TYPE {
StorageType::Table => {
let (table_components, added_ticks, changed_ticks) =
fetch.table_data.debug_checked_unwrap();
Ref {
value: table_components.get(table_row.index()).deref(),
ticks: Ticks {
added: added_ticks.get(table_row.index()).deref(),
changed: changed_ticks.get(table_row.index()).deref(),
this_run: fetch.this_run,
last_run: fetch.last_run,
},
}
}
StorageType::SparseSet => {
let (component, ticks) = fetch
.sparse_set
.debug_checked_unwrap()
.get_with_ticks(entity)
.debug_checked_unwrap();
Ref {
value: component.deref(),
ticks: Ticks::from_tick_cells(ticks, fetch.last_run, fetch.this_run),
}
}
}
}
fn update_component_access(
&component_id: &ComponentId,
access: &mut FilteredAccess<ComponentId>,
) {
assert!(
!access.access().has_write(component_id),
"&{} conflicts with a previous access in this query. Shared access cannot coincide with exclusive access.",
std::any::type_name::<T>(),
);
access.add_read(component_id);
}
fn update_archetype_component_access(
&component_id: &ComponentId,
archetype: &Archetype,
access: &mut Access<ArchetypeComponentId>,
) {
if let Some(archetype_component_id) = archetype.get_archetype_component_id(component_id) {
access.add_read(archetype_component_id);
}
}
fn init_state(world: &mut World) -> ComponentId {
world.init_component::<T>()
}
fn matches_component_set(
&state: &ComponentId,
set_contains_id: &impl Fn(ComponentId) -> bool,
) -> bool {
set_contains_id(state)
}
}
/// SAFETY: access is read only
unsafe impl<'__w, T: Component> ReadOnlyWorldQuery for Ref<'__w, T> {}
#[doc(hidden)]
pub struct WriteFetch<'w, T> {
// T::Storage = TableStorage
table_data: Option<(
ThinSlicePtr<'w, UnsafeCell<T>>,
ThinSlicePtr<'w, UnsafeCell<Tick>>,
ThinSlicePtr<'w, UnsafeCell<Tick>>,
)>,
// T::Storage = SparseStorage
sparse_set: Option<&'w ComponentSparseSet>,
last_run: Tick,
this_run: Tick,
}