//! Types that enable reflection support.
use crate::{
change_detection::Mut,
component::Component,
entity::{Entity, EntityMap, MapEntities, MapEntitiesError},
system::Resource,
world::{FromWorld, World},
};
use bevy_reflect::{
impl_from_reflect_value, impl_reflect_value, FromType, Reflect, ReflectDeserialize,
ReflectSerialize,
};
/// 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::insert()`].
pub insert: fn(&mut World, Entity, &dyn Reflect),
/// Function pointer implementing [`ReflectComponent::apply()`].
pub apply: fn(&mut World, Entity, &dyn Reflect),
/// Function pointer implementing [`ReflectComponent::apply_or_insert()`].
pub apply_or_insert: fn(&mut World, Entity, &dyn Reflect),
/// Function pointer implementing [`ReflectComponent::remove()`].
pub remove: fn(&mut World, Entity),
/// Function pointer implementing [`ReflectComponent::reflect()`].
pub reflect: fn(&World, Entity) -> Option<&dyn Reflect>,
/// Function pointer implementing [`ReflectComponent::reflect_mut()`].
pub reflect_mut: unsafe fn(&World, Entity) -> Option<Mut<dyn Reflect>>,
/// Function pointer implementing [`ReflectComponent::copy()`].
pub copy: fn(&World, &mut World, Entity, Entity),
}
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 {
/// Insert a reflected [`Component`] into the entity like [`insert()`](crate::world::EntityMut::insert).
///
/// # Panics
///
/// Panics if there is no such entity.
pub fn insert(&self, world: &mut World, entity: Entity, component: &dyn Reflect) {
(self.0.insert)(world, 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 or the `entity` does not exist.
pub fn apply(&self, world: &mut World, entity: Entity, component: &dyn Reflect) {
(self.0.apply)(world, 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.
///
/// # Panics
///
/// Panics if the `entity` does not exist.
pub fn apply_or_insert(&self, world: &mut World, entity: Entity, component: &dyn Reflect) {
(self.0.apply_or_insert)(world, entity, component);
}
/// Removes this [`Component`] type from the entity. Does nothing if it doesn't exist.
///
/// # Panics
///
/// Panics if there is no [`Component`] of the given type or the `entity` does not exist.
pub fn remove(&self, world: &mut World, entity: Entity) {
(self.0.remove)(world, entity);
}
/// Gets the value of this [`Component`] type from the entity as a reflected reference.
pub fn reflect<'a>(&self, world: &'a World, entity: Entity) -> Option<&'a dyn Reflect> {
(self.0.reflect)(world, entity)
}
/// Gets the value of this [`Component`] type from the entity as a mutable reflected reference.
pub fn reflect_mut<'a>(
&self,
world: &'a mut World,
entity: Entity,
) -> Option<Mut<'a, dyn Reflect>> {
// SAFETY: unique world access
unsafe { (self.0.reflect_mut)(world, 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 in an exclusive system to avoid sharing across threads (or use a
/// scheduler that enforces safe memory access).
/// * Don't call this method more than once in the same scope for a given [`Component`].
pub unsafe fn reflect_unchecked_mut<'a>(
&self,
world: &'a World,
entity: Entity,
) -> Option<Mut<'a, dyn Reflect>> {
(self.0.reflect_mut)(world, entity)
}
/// 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 {
insert: |world, entity, reflected_component| {
let mut component = C::from_world(world);
component.apply(reflected_component);
world.entity_mut(entity).insert(component);
},
apply: |world, entity, reflected_component| {
let mut component = world.get_mut::<C>(entity).unwrap();
component.apply(reflected_component);
},
apply_or_insert: |world, entity, reflected_component| {
if let Some(mut component) = world.get_mut::<C>(entity) {
component.apply(reflected_component);
} else {
let mut component = C::from_world(world);
component.apply(reflected_component);
world.entity_mut(entity).insert(component);
}
},
remove: |world, entity| {
world.entity_mut(entity).remove::<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: |world, entity| {
world
.get_entity(entity)?
.get::<C>()
.map(|c| c as &dyn Reflect)
},
reflect_mut: |world, entity| {
// SAFETY: reflect_mut is an unsafe function pointer used by `reflect_unchecked_mut` which promises to never
// produce aliasing mutable references, and reflect_mut, which has mutable world access
unsafe {
world
.get_entity(entity)?
.get_unchecked_mut::<C>(world.last_change_tick(), world.read_change_tick())
.map(|c| Mut {
value: c.value as &mut dyn Reflect,
ticks: c.ticks,
})
}
},
})
}
}
/// A struct used to operate on reflected [`Resource`] of a type.
///
/// A [`ReflectResource`] for type `T` can be obtained via
/// [`bevy_reflect::TypeRegistration::data`].
#[derive(Clone)]
pub struct ReflectResource(ReflectResourceFns);
/// The raw function pointers needed to make up a [`ReflectResource`].
///
/// This is used when creating custom implementations of [`ReflectResource`] with
/// [`ReflectResource::new()`].
///
/// > **Note:**
/// > Creating custom implementations of [`ReflectResource`] is an advanced feature that most users
/// > will not need.
/// > Usually a [`ReflectResource`] is created for a type by deriving [`Reflect`]
/// > and adding the `#[reflect(Resource)]` attribute.
/// > After adding the component to the [`TypeRegistry`][bevy_reflect::TypeRegistry],
/// > its [`ReflectResource`] can then be retrieved when needed.
///
/// Creating a custom [`ReflectResource`] may be useful if you need to create new resource types at
/// runtime, for example, for scripting implementations.
///
/// By creating a custom [`ReflectResource`] and inserting it into a type's
/// [`TypeRegistration`][bevy_reflect::TypeRegistration],
/// you can modify the way that reflected resources of that type will be inserted into the bevy
/// world.
#[derive(Clone)]
pub struct ReflectResourceFns {
/// Function pointer implementing [`ReflectResource::insert()`].
pub insert: fn(&mut World, &dyn Reflect),
/// Function pointer implementing [`ReflectResource::apply()`].
pub apply: fn(&mut World, &dyn Reflect),
/// Function pointer implementing [`ReflectResource::apply_or_insert()`].
pub apply_or_insert: fn(&mut World, &dyn Reflect),
/// Function pointer implementing [`ReflectResource::remove()`].
pub remove: fn(&mut World),
/// Function pointer implementing [`ReflectResource::reflect()`].
pub reflect: fn(&World) -> Option<&dyn Reflect>,
/// Function pointer implementing [`ReflectResource::reflect_unchecked_mut()`].
pub reflect_unchecked_mut: unsafe fn(&World) -> Option<Mut<dyn Reflect>>,
/// Function pointer implementing [`ReflectResource::copy()`].
pub copy: fn(&World, &mut World),
}
impl ReflectResourceFns {
/// Get the default set of [`ReflectResourceFns`] for a specific resource 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: Resource + Reflect + FromWorld>() -> Self {
<ReflectResource as FromType<T>>::from_type().0
}
}
impl ReflectResource {
/// Insert a reflected [`Resource`] into the world like [`insert()`](World::insert_resource).
pub fn insert(&self, world: &mut World, resource: &dyn Reflect) {
(self.0.insert)(world, resource);
}
/// Uses reflection to set the value of this [`Resource`] type in the world to the given value.
///
/// # Panics
///
/// Panics if there is no [`Resource`] of the given type.
pub fn apply(&self, world: &mut World, resource: &dyn Reflect) {
(self.0.apply)(world, resource);
}
/// Uses reflection to set the value of this [`Resource`] type in the world to the given value or insert a new one if it does not exist.
pub fn apply_or_insert(&self, world: &mut World, resource: &dyn Reflect) {
(self.0.apply_or_insert)(world, resource);
}
/// Removes this [`Resource`] type from the world. Does nothing if it doesn't exist.
pub fn remove(&self, world: &mut World) {
(self.0.remove)(world);
}
/// Gets the value of this [`Resource`] type from the world as a reflected reference.
pub fn reflect<'a>(&self, world: &'a World) -> Option<&'a dyn Reflect> {
(self.0.reflect)(world)
}
/// Gets the value of this [`Resource`] type from the world as a mutable reflected reference.
pub fn reflect_mut<'a>(&self, world: &'a mut World) -> Option<Mut<'a, dyn Reflect>> {
// SAFETY: unique world access
unsafe { (self.0.reflect_unchecked_mut)(world) }
}
/// # 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 in an exclusive system to avoid sharing across threads (or use a
/// scheduler that enforces safe memory access).
/// * Don't call this method more than once in the same scope for a given [`Resource`].
pub unsafe fn reflect_unchecked_mut<'a>(
&self,
world: &'a World,
) -> Option<Mut<'a, dyn Reflect>> {
// SAFETY: caller promises to uphold uniqueness guarantees
(self.0.reflect_unchecked_mut)(world)
}
/// Gets the value of this [`Resource`] type from `source_world` and [applies](Self::apply()) it to the value of this [`Resource`] type in `destination_world`.
///
/// # Panics
///
/// Panics if there is no [`Resource`] of the given type.
pub fn copy(&self, source_world: &World, destination_world: &mut World) {
(self.0.copy)(source_world, destination_world);
}
/// Create a custom implementation of [`ReflectResource`].
///
/// 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(Resource)]` component
/// to generate a [`ReflectResource`] implementation automatically.
///
/// See [`ReflectResourceFns`] for more information.
pub fn new(&self, fns: ReflectResourceFns) -> Self {
Self(fns)
}
}
impl<C: Resource + Reflect + FromWorld> FromType<C> for ReflectResource {
fn from_type() -> Self {
ReflectResource(ReflectResourceFns {
insert: |world, reflected_resource| {
let mut resource = C::from_world(world);
resource.apply(reflected_resource);
world.insert_resource(resource);
},
apply: |world, reflected_resource| {
let mut resource = world.resource_mut::<C>();
resource.apply(reflected_resource);
},
apply_or_insert: |world, reflected_resource| {
if let Some(mut resource) = world.get_resource_mut::<C>() {
resource.apply(reflected_resource);
} else {
let mut resource = C::from_world(world);
resource.apply(reflected_resource);
world.insert_resource(resource);
}
},
remove: |world| {
world.remove_resource::<C>();
},
reflect: |world| world.get_resource::<C>().map(|res| res as &dyn Reflect),
reflect_unchecked_mut: |world| {
// SAFETY: all usages of `reflect_unchecked_mut` guarantee that there is either a single mutable
// reference or multiple immutable ones alive at any given point
unsafe {
world.get_resource_unchecked_mut::<C>().map(|res| Mut {
value: res.value as &mut dyn Reflect,
ticks: res.ticks,
})
}
},
copy: |source_world, destination_world| {
let source_resource = source_world.resource::<C>();
let mut destination_resource = C::from_world(destination_world);
destination_resource.apply(source_resource);
destination_world.insert_resource(destination_resource);
},
})
}
}
impl_reflect_value!(Entity(Hash, PartialEq, Serialize, Deserialize));
impl_from_reflect_value!(Entity);
#[derive(Clone)]
pub struct ReflectMapEntities {
map_entities: fn(&mut World, &EntityMap) -> Result<(), MapEntitiesError>,
}
impl ReflectMapEntities {
pub fn map_entities(
&self,
world: &mut World,
entity_map: &EntityMap,
) -> Result<(), MapEntitiesError> {
(self.map_entities)(world, entity_map)
}
}
impl<C: Component + MapEntities> FromType<C> for ReflectMapEntities {
fn from_type() -> Self {
ReflectMapEntities {
map_entities: |world, entity_map| {
for entity in entity_map.values() {
if let Some(mut component) = world.get_mut::<C>(entity) {
component.map_entities(entity_map)?;
}
}
Ok(())
},
}
}
}