Upstream reflect_query

crates/bevy_ecs/src/change_detection.rs

@@ -551,7 +551,7 @@ impl<'a, T: ?Sized> Ref<'a, T> {
     ///
     /// This doesn't do anything else than call `f` on the wrapped value.
     /// This is equivalent to [`Mut::map_unchanged`].
-    pub fn map<U>(self, f: impl FnOnce(&T) -> &U) -> Ref<'a, U> {
+    pub fn map<U: ?Sized>(self, f: impl FnOnce(&T) -> &U) -> Ref<'a, U> {
         Ref {
             value: f(self.value),
             ticks: self.ticks,

crates/bevy_ecs/src/reflect/component.rs

@@ -0,0 +1,335 @@
+use super::queryable;
+use super::reflect_query_structs::{EntityQuerydyn, MutQuerydyn, Querydyn, RefQuerydyn};
+use crate::{
+    change_detection::{Mut, Ref},
+    component::Component,
+    entity::Entity,
+    query::QuerySingleError,
+    world::{unsafe_world_cell::UnsafeEntityCell, EntityMut, EntityRef, FromWorld, World},
+};
+use bevy_reflect::{FromType, Reflect};
+
+#[rustfmt::skip] // skip: this makes reading those generated doc string a bit easier.
+macro_rules! docs {
+    (fn $queryable_method:literal) => {
+        concat!("Function pointer implementing [`ReflectComponent::", $queryable_method, "`].")
+    };
+    (single $query_equivalent:literal, $output:literal, $output_link:literal) => {
+        concat!(
+"Get a single [`", $output, "`](", $output_link, r#") of the underyling
+[`Component`] from `World`, failing if there isn't exactly one `Entity`
+matching this description.
+
+Consider using [`ReflectComponent::"#, $query_equivalent, r#"`] followed
+by `.next()` if you want to get a value even if there is more than one
+`Entity` with the underlying `Component`.
+
+# Errors
+
+This will return an `Err` if:
+
+ - There is no `Entity` with the underyling `Component` in `world`.
+ - There is more than one `Entity` with the underyling `Component` in `world`."#
+        )
+    };
+
+    (query
+        $querydyn:literal, $single_equivalent:literal, $method_name:literal,
+        $item:literal, $item_link:literal $(,)?
+    ) => {
+        concat!(
+"Get a [`", $querydyn, "`] to iterate over all\n\
+[`", $item, "`](", $item_link, r#") with the underlying
+[`Component`] from `world`.
+
+Use [`ReflectComponent::"#, $single_equivalent, r#"`] for a version that returns
+a single element directly."#
+        )
+    };
+}
+
+/// A struct used to operate on reflected [`Component`] of a type.
+///
+/// A [`ReflectComponent`] for type `T` can be obtained via
+/// [`bevy_reflect::TypeRegistration::data`].
+#[derive(Clone)]
+pub struct ReflectComponent(ReflectComponentFns);
+
+/// The raw function pointers needed to make up a [`ReflectComponent`].
+///
+/// This is used when creating custom implementations of [`ReflectComponent`] with
+/// [`ReflectComponent::new()`].
+///
+/// > **Note:**
+/// > Creating custom implementations of [`ReflectComponent`] is an advanced feature that most users
+/// > will not need.
+/// > Usually a [`ReflectComponent`] is created for a type by deriving [`Reflect`]
+/// > and adding the `#[reflect(Component)]` attribute.
+/// > After adding the component to the [`TypeRegistry`][bevy_reflect::TypeRegistry],
+/// > its [`ReflectComponent`] can then be retrieved when needed.
+///
+/// Creating a custom [`ReflectComponent`] may be useful if you need to create new component types
+/// at runtime, for example, for scripting implementations.
+///
+/// By creating a custom [`ReflectComponent`] and inserting it into a type's
+/// [`TypeRegistration`][bevy_reflect::TypeRegistration],
+/// you can modify the way that reflected components of that type will be inserted into the Bevy
+/// world.
+#[derive(Clone)]
+pub struct ReflectComponentFns {
+    /// Function pointer implementing [`ReflectComponent::from_world()`].
+    pub from_world: fn(&mut World) -> Box<dyn Reflect>,
+    /// Function pointer implementing [`ReflectComponent::insert()`].
+    pub insert: fn(&mut EntityMut, &dyn Reflect),
+    /// Function pointer implementing [`ReflectComponent::apply()`].
+    pub apply: fn(&mut EntityMut, &dyn Reflect),
+    /// Function pointer implementing [`ReflectComponent::apply_or_insert()`].
+    pub apply_or_insert: fn(&mut EntityMut, &dyn Reflect),
+    /// Function pointer implementing [`ReflectComponent::remove()`].
+    pub remove: fn(&mut EntityMut),
+    /// Function pointer implementing [`ReflectComponent::contains()`].
+    pub contains: fn(EntityRef) -> bool,
+    /// Function pointer implementing [`ReflectComponent::reflect()`].
+    pub reflect: fn(EntityRef) -> Option<&dyn Reflect>,
+    /// Function pointer implementing [`ReflectComponent::reflect_mut()`].
+    pub reflect_mut: for<'a> fn(&'a mut EntityMut<'_>) -> Option<Mut<'a, dyn Reflect>>,
+    /// Function pointer implementing [`ReflectComponent::reflect_unchecked_mut()`].
+    ///
+    /// # Safety
+    /// The function may only be called with an [`UnsafeEntityCell`] that can be used to mutably access the relevant component on the given entity.
+    pub reflect_unchecked_mut: unsafe fn(UnsafeEntityCell<'_>) -> Option<Mut<'_, dyn Reflect>>,
+    /// Function pointer implementing [`ReflectComponent::copy()`].
+    pub copy: fn(&World, &mut World, Entity, Entity),
+
+    /// Function pointer implementing [`ReflectComponent::reflect_ref()`].
+    pub reflect_ref: fn(EntityRef) -> Option<Ref<dyn Reflect>>,
+
+    /// Function pointer implementing [`ReflectComponent::get_single()`].
+    pub get_single: fn(&mut World) -> Result<&dyn Reflect, QuerySingleError>,
+    /// Function pointer implementing [`ReflectComponent::get_single_entity()`].
+    pub get_single_entity: fn(&mut World) -> Result<Entity, QuerySingleError>,
+    /// Function pointer implementing [`ReflectComponent::get_single_ref()`].
+    pub get_single_ref: fn(&mut World) -> Result<Ref<dyn Reflect>, QuerySingleError>,
+    /// Function pointer implementing [`ReflectComponent::get_single_mut()`].
+    pub get_single_mut: fn(&mut World) -> Result<Mut<dyn Reflect>, QuerySingleError>,
+
+    /// Function pointer implementing [`ReflectComponent::query()`].
+    pub query: fn(&mut World) -> Querydyn,
+    /// Function pointer implementing [`ReflectComponent::query_entities()`].
+    pub query_entities: fn(&mut World) -> EntityQuerydyn,
+    /// Function pointer implementing [`ReflectComponent::query_ref()`].
+    pub query_ref: fn(&mut World) -> RefQuerydyn,
+    /// Function pointer implementing [`ReflectComponent::query_mut()`].
+    pub query_mut: fn(&mut World) -> MutQuerydyn,
+}
+
+impl ReflectComponentFns {
+    /// Get the default set of [`ReflectComponentFns`] for a specific component type using its
+    /// [`FromType`] implementation.
+    ///
+    /// This is useful if you want to start with the default implementation before overriding some
+    /// of the functions to create a custom implementation.
+    pub fn new<T: Component + Reflect + FromWorld>() -> Self {
+        <ReflectComponent as FromType<T>>::from_type().0
+    }
+}
+
+impl ReflectComponent {
+    /// Constructs default reflected [`Component`] from world using [`from_world()`](FromWorld::from_world).
+    pub fn from_world(&self, world: &mut World) -> Box<dyn Reflect> {
+        (self.0.from_world)(world)
+    }
+
+    /// Insert a reflected [`Component`] into the entity like [`insert()`](crate::world::EntityMut::insert).
+    pub fn insert(&self, entity: &mut EntityMut, component: &dyn Reflect) {
+        (self.0.insert)(entity, component);
+    }
+
+    /// Uses reflection to set the value of this [`Component`] type in the entity to the given value.
+    ///
+    /// # Panics
+    ///
+    /// Panics if there is no [`Component`] of the given type.
+    pub fn apply(&self, entity: &mut EntityMut, component: &dyn Reflect) {
+        (self.0.apply)(entity, component);
+    }
+
+    /// Uses reflection to set the value of this [`Component`] type in the entity to the given value or insert a new one if it does not exist.
+    pub fn apply_or_insert(&self, entity: &mut EntityMut, component: &dyn Reflect) {
+        (self.0.apply_or_insert)(entity, component);
+    }
+
+    /// Removes this [`Component`] type from the entity. Does nothing if it doesn't exist.
+    pub fn remove(&self, entity: &mut EntityMut) {
+        (self.0.remove)(entity);
+    }
+
+    /// Returns whether entity contains this [`Component`]
+    pub fn contains(&self, entity: EntityRef) -> bool {
+        (self.0.contains)(entity)
+    }
+
+    /// Gets the value of this [`Component`] type from the entity as a reflected reference.
+    pub fn reflect<'a>(&self, entity: EntityRef<'a>) -> Option<&'a dyn Reflect> {
+        (self.0.reflect)(entity)
+    }
+
+    /// Gets the value of this [`Component`] type from the entity as a mutable reflected reference.
+    pub fn reflect_mut<'a>(&self, entity: &'a mut EntityMut<'_>) -> Option<Mut<'a, dyn Reflect>> {
+        (self.0.reflect_mut)(entity)
+    }
+
+    /// # Safety
+    /// This method does not prevent you from having two mutable pointers to the same data,
+    /// violating Rust's aliasing rules. To avoid this:
+    /// * Only call this method with a [`UnsafeEntityCell`] that may be used to mutably access the component on the entity `entity`
+    /// * Don't call this method more than once in the same scope for a given [`Component`].
+    pub unsafe fn reflect_unchecked_mut<'a>(
+        &self,
+        entity: UnsafeEntityCell<'a>,
+    ) -> Option<Mut<'a, dyn Reflect>> {
+        // SAFETY: safety requirements deferred to caller
+        (self.0.reflect_unchecked_mut)(entity)
+    }
+
+    #[doc = docs!(single "query", "&dyn Reflect", "Reflect")]
+    pub fn get_single<'a>(
+        &self,
+        world: &'a mut World,
+    ) -> Result<&'a dyn Reflect, QuerySingleError> {
+        (self.0.get_single)(world)
+    }
+    #[doc = docs!(single "query_ref", "Ref<dyn Reflect>", "Ref")]
+    pub fn get_single_ref<'a>(
+        &self,
+        world: &'a mut World,
+    ) -> Result<Ref<'a, dyn Reflect>, QuerySingleError> {
+        (self.0.get_single_ref)(world)
+    }
+    #[doc = docs!(single "query_mut", "Mut<dyn Reflect>", "Mut")]
+    pub fn get_single_mut<'a>(
+        &self,
+        world: &'a mut World,
+    ) -> Result<Mut<'a, dyn Reflect>, QuerySingleError> {
+        (self.0.get_single_mut)(world)
+    }
+    #[doc = docs!(single "query_entities", "Entity", "Entity")]
+    pub fn get_single_entity(&self, world: &mut World) -> Result<Entity, QuerySingleError> {
+        (self.0.get_single_entity)(world)
+    }
+
+    #[doc = docs!(query "Querydyn", "get_single", "query", "&dyn Reflect", "Reflect")]
+    pub fn query(&self, world: &mut World) -> Querydyn {
+        (self.0.query)(world)
+    }
+    #[doc = docs!(query "EntityQuerydyn", "get_single_entity", "query_entities", "Entity", "Entity")]
+    pub fn query_entities(&self, world: &mut World) -> EntityQuerydyn {
+        (self.0.query_entities)(world)
+    }
+    #[doc = docs!(query "RefQuerydyn", "get_single_ref", "query_ref", "Ref<dyn Reflect>", "Ref")]
+    pub fn query_ref(&self, world: &mut World) -> RefQuerydyn {
+        (self.0.query_ref)(world)
+    }
+    #[doc = docs!(query "MutQuerydyn", "get_single_mut", "query_mut", "Mut<dyn Reflect>", "Mut")]
+    pub fn query_mut(&self, world: &mut World) -> MutQuerydyn {
+        (self.0.query_mut)(world)
+    }
+    /// Gets the value of this [`Component`] type from entity from `source_world` and [applies](Self::apply()) it to the value of this [`Component`] type in entity in `destination_world`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if there is no [`Component`] of the given type or either entity does not exist.
+    pub fn copy(
+        &self,
+        source_world: &World,
+        destination_world: &mut World,
+        source_entity: Entity,
+        destination_entity: Entity,
+    ) {
+        (self.0.copy)(
+            source_world,
+            destination_world,
+            source_entity,
+            destination_entity,
+        );
+    }
+
+    /// Create a custom implementation of [`ReflectComponent`].
+    ///
+    /// This is an advanced feature,
+    /// useful for scripting implementations,
+    /// that should not be used by most users
+    /// unless you know what you are doing.
+    ///
+    /// Usually you should derive [`Reflect`] and add the `#[reflect(Component)]` component
+    /// to generate a [`ReflectComponent`] implementation automatically.
+    ///
+    /// See [`ReflectComponentFns`] for more information.
+    pub fn new(fns: ReflectComponentFns) -> Self {
+        Self(fns)
+    }
+}
+
+impl<C: Component + Reflect + FromWorld> FromType<C> for ReflectComponent {
+    fn from_type() -> Self {
+        ReflectComponent(ReflectComponentFns {
+            from_world: |world| Box::new(C::from_world(world)),
+            insert: |entity, reflected_component| {
+                let mut component = entity.world_scope(|world| C::from_world(world));
+                component.apply(reflected_component);
+                entity.insert(component);
+            },
+            apply: |entity, reflected_component| {
+                let mut component = entity.get_mut::<C>().unwrap();
+                component.apply(reflected_component);
+            },
+            apply_or_insert: |entity, reflected_component| {
+                if let Some(mut component) = entity.get_mut::<C>() {
+                    component.apply(reflected_component);
+                } else {
+                    let mut component = entity.world_scope(|world| C::from_world(world));
+                    component.apply(reflected_component);
+                    entity.insert(component);
+                }
+            },
+            remove: |entity| {
+                entity.remove::<C>();
+            },
+            contains: |entity| entity.contains::<C>(),
+            copy: |source_world, destination_world, source_entity, destination_entity| {
+                let source_component = source_world.get::<C>(source_entity).unwrap();
+                let mut destination_component = C::from_world(destination_world);
+                destination_component.apply(source_component);
+                destination_world
+                    .entity_mut(destination_entity)
+                    .insert(destination_component);
+            },
+            reflect: |entity| entity.get::<C>().map(|c| c as &dyn Reflect),
+            reflect_mut: |entity| {
+                entity.get_mut::<C>().map(|c| Mut {
+                    value: c.value as &mut dyn Reflect,
+                    ticks: c.ticks,
+                })
+            },
+            reflect_unchecked_mut: |entity| {
+                // SAFETY: reflect_unchecked_mut is an unsafe function pointer used by
+                // `reflect_unchecked_mut` which must be called with an UnsafeEntityCell with access to the the component `C` on the `entity`
+                unsafe {
+                    entity.get_mut::<C>().map(|c| Mut {
+                        value: c.value as &mut dyn Reflect,
+                        ticks: c.ticks,
+                    })
+                }
+            },
+            reflect_ref: queryable::reflect_ref::<C>,
+            get_single: queryable::get_single::<C>,
+            get_single_entity: queryable::get_single_entity::<C>,
+            get_single_ref: queryable::get_single_ref::<C>,
+            get_single_mut: queryable::get_single_mut::<C>,
+            query: queryable::query::<C>,
+            query_entities: queryable::query_entities::<C>,
+            query_ref: queryable::query_ref::<C>,
+            query_mut: queryable::query_mut::<C>,
+        })
+    }
+}