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Extract clone-related items from component

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This commit is contained in:
Giacomo Stevanato 2025-07-09 17:47:11 +02:00
parent 9e0f9023ce
commit 2f16cadac5
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2 changed files with 222 additions and 211 deletions
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217
crates/bevy_ecs/src/component/clone.rs Normal file
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@ -0,0 +1,217 @@
use alloc::boxed::Box;
use bevy_ptr::OwningPtr;
use core::marker::PhantomData;
use crate::component::Component;
use crate::entity::{ComponentCloneCtx, EntityMapper, SourceComponent};
use crate::world::World;
/// Function type that can be used to clone an entity.
pub type ComponentCloneFn = fn(&SourceComponent, &mut ComponentCloneCtx);
/// The clone behavior to use when cloning a [`Component`].
#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub enum ComponentCloneBehavior {
/// Uses the default behavior (which is passed to [`ComponentCloneBehavior::resolve`])
#[default]
Default,
/// Do not clone this component.
Ignore,
/// Uses a custom [`ComponentCloneFn`].
Custom(ComponentCloneFn),
}
impl ComponentCloneBehavior {
/// Set clone handler based on `Clone` trait.
///
/// If set as a handler for a component that is not the same as the one used to create this handler, it will panic.
pub fn clone<C: Component + Clone>() -> Self {
Self::Custom(component_clone_via_clone::<C>)
}
/// Set clone handler based on `Reflect` trait.
#[cfg(feature = "bevy_reflect")]
pub fn reflect() -> Self {
Self::Custom(component_clone_via_reflect)
}
/// Returns the "global default"
pub fn global_default_fn() -> ComponentCloneFn {
#[cfg(feature = "bevy_reflect")]
return component_clone_via_reflect;
#[cfg(not(feature = "bevy_reflect"))]
return component_clone_ignore;
}
/// Resolves the [`ComponentCloneBehavior`] to a [`ComponentCloneFn`]. If [`ComponentCloneBehavior::Default`] is
/// specified, the given `default` function will be used.
pub fn resolve(&self, default: ComponentCloneFn) -> ComponentCloneFn {
match self {
ComponentCloneBehavior::Default => default,
ComponentCloneBehavior::Ignore => component_clone_ignore,
ComponentCloneBehavior::Custom(custom) => *custom,
}
}
}
/// Component [clone handler function](ComponentCloneFn) implemented using the [`Clone`] trait.
/// Can be [set](Component::clone_behavior) as clone handler for the specific component it is implemented for.
/// It will panic if set as handler for any other component.
///
pub fn component_clone_via_clone<C: Clone + Component>(
source: &SourceComponent,
ctx: &mut ComponentCloneCtx,
) {
if let Some(component) = source.read::<C>() {
ctx.write_target_component(component.clone());
}
}
/// Component [clone handler function](ComponentCloneFn) implemented using reflect.
/// Can be [set](Component::clone_behavior) as clone handler for any registered component,
/// but only reflected components will be cloned.
///
/// To clone a component using this handler, the following must be true:
/// - World has [`AppTypeRegistry`](crate::reflect::AppTypeRegistry)
/// - Component has [`TypeId`]
/// - Component is registered
/// - Component has [`ReflectFromPtr`](bevy_reflect::ReflectFromPtr) registered
/// - Component can be cloned via [`PartialReflect::reflect_clone`] _or_ has one of the following registered: [`ReflectFromReflect`](bevy_reflect::ReflectFromReflect),
/// [`ReflectDefault`](bevy_reflect::std_traits::ReflectDefault), [`ReflectFromWorld`](crate::reflect::ReflectFromWorld)
///
/// If any of the conditions is not satisfied, the component will be skipped.
///
/// See [`EntityClonerBuilder`](crate::entity::EntityClonerBuilder) for details.
///
/// [`PartialReflect::reflect_clone`]: bevy_reflect::PartialReflect::reflect_clone
#[cfg(feature = "bevy_reflect")]
pub fn component_clone_via_reflect(source: &SourceComponent, ctx: &mut ComponentCloneCtx) {
let Some(app_registry) = ctx.type_registry().cloned() else {
return;
};
let registry = app_registry.read();
let Some(source_component_reflect) = source.read_reflect(&registry) else {
return;
};
let component_info = ctx.component_info();
// checked in read_source_component_reflect
let type_id = component_info.type_id().unwrap();
// Try to clone using `reflect_clone`
if let Ok(mut component) = source_component_reflect.reflect_clone() {
if let Some(reflect_component) =
registry.get_type_data::<crate::reflect::ReflectComponent>(type_id)
{
reflect_component.map_entities(&mut *component, ctx.entity_mapper());
}
drop(registry);
ctx.write_target_component_reflect(component);
return;
}
// Try to clone using ReflectFromReflect
if let Some(reflect_from_reflect) =
registry.get_type_data::<bevy_reflect::ReflectFromReflect>(type_id)
{
if let Some(mut component) =
reflect_from_reflect.from_reflect(source_component_reflect.as_partial_reflect())
{
if let Some(reflect_component) =
registry.get_type_data::<crate::reflect::ReflectComponent>(type_id)
{
reflect_component.map_entities(&mut *component, ctx.entity_mapper());
}
drop(registry);
ctx.write_target_component_reflect(component);
return;
}
}
// Else, try to clone using ReflectDefault
if let Some(reflect_default) =
registry.get_type_data::<bevy_reflect::std_traits::ReflectDefault>(type_id)
{
let mut component = reflect_default.default();
component.apply(source_component_reflect.as_partial_reflect());
drop(registry);
ctx.write_target_component_reflect(component);
return;
}
// Otherwise, try to clone using ReflectFromWorld
if let Some(reflect_from_world) =
registry.get_type_data::<crate::reflect::ReflectFromWorld>(type_id)
{
let reflect_from_world = reflect_from_world.clone();
let source_component_cloned = source_component_reflect.to_dynamic();
let component_layout = component_info.layout();
let target = ctx.target();
let component_id = ctx.component_id();
drop(registry);
ctx.queue_deferred(move |world: &mut World, mapper: &mut dyn EntityMapper| {
let mut component = reflect_from_world.from_world(world);
assert_eq!(type_id, (*component).type_id());
component.apply(source_component_cloned.as_partial_reflect());
if let Some(reflect_component) = app_registry
.read()
.get_type_data::<crate::reflect::ReflectComponent>(type_id)
{
reflect_component.map_entities(&mut *component, mapper);
}
// SAFETY:
// - component_id is from the same world as target entity
// - component is a valid value represented by component_id
unsafe {
let raw_component_ptr =
core::ptr::NonNull::new_unchecked(Box::into_raw(component).cast::<u8>());
world
.entity_mut(target)
.insert_by_id(component_id, OwningPtr::new(raw_component_ptr));
if component_layout.size() > 0 {
// Ensure we don't attempt to deallocate zero-sized components
alloc::alloc::dealloc(raw_component_ptr.as_ptr(), component_layout);
}
}
});
}
}
/// Noop implementation of component clone handler function.
///
/// See [`EntityClonerBuilder`](crate::entity::EntityClonerBuilder) for details.
pub fn component_clone_ignore(_source: &SourceComponent, _ctx: &mut ComponentCloneCtx) {}
/// Wrapper for components clone specialization using autoderef.
#[doc(hidden)]
pub struct DefaultCloneBehaviorSpecialization<T>(PhantomData<T>);
impl<T> Default for DefaultCloneBehaviorSpecialization<T> {
fn default() -> Self {
Self(PhantomData)
}
}
/// Base trait for components clone specialization using autoderef.
#[doc(hidden)]
pub trait DefaultCloneBehaviorBase {
fn default_clone_behavior(&self) -> ComponentCloneBehavior;
}
impl<C> DefaultCloneBehaviorBase for DefaultCloneBehaviorSpecialization<C> {
fn default_clone_behavior(&self) -> ComponentCloneBehavior {
ComponentCloneBehavior::Default
}
}
/// Specialized trait for components clone specialization using autoderef.
#[doc(hidden)]
pub trait DefaultCloneBehaviorViaClone {
fn default_clone_behavior(&self) -> ComponentCloneBehavior;
}
impl<C: Clone + Component> DefaultCloneBehaviorViaClone for &DefaultCloneBehaviorSpecialization<C> {
fn default_clone_behavior(&self) -> ComponentCloneBehavior {
ComponentCloneBehavior::clone::<C>()
}
}

216
crates/bevy_ecs/src/component/mod.rs
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@ -1,10 +1,14 @@
//! Types for declaring and storing [`Component`]s.
mod clone;
pub use clone::*;
use crate::{
archetype::ArchetypeFlags,
bundle::BundleInfo,
change_detection::{MaybeLocation, MAX_CHANGE_AGE},
entity::{ComponentCloneCtx, Entity, EntityMapper, SourceComponent},
entity::{Entity, EntityMapper},
lifecycle::{ComponentHook, ComponentHooks},
query::DebugCheckedUnwrap,
resource::Resource,
@ -1035,54 +1039,6 @@ impl ComponentDescriptor {
}
}
/// Function type that can be used to clone an entity.
pub type ComponentCloneFn = fn(&SourceComponent, &mut ComponentCloneCtx);
/// The clone behavior to use when cloning a [`Component`].
#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub enum ComponentCloneBehavior {
/// Uses the default behavior (which is passed to [`ComponentCloneBehavior::resolve`])
#[default]
Default,
/// Do not clone this component.
Ignore,
/// Uses a custom [`ComponentCloneFn`].
Custom(ComponentCloneFn),
}
impl ComponentCloneBehavior {
/// Set clone handler based on `Clone` trait.
///
/// If set as a handler for a component that is not the same as the one used to create this handler, it will panic.
pub fn clone<C: Component + Clone>() -> Self {
Self::Custom(component_clone_via_clone::<C>)
}
/// Set clone handler based on `Reflect` trait.
#[cfg(feature = "bevy_reflect")]
pub fn reflect() -> Self {
Self::Custom(component_clone_via_reflect)
}
/// Returns the "global default"
pub fn global_default_fn() -> ComponentCloneFn {
#[cfg(feature = "bevy_reflect")]
return component_clone_via_reflect;
#[cfg(not(feature = "bevy_reflect"))]
return component_clone_ignore;
}
/// Resolves the [`ComponentCloneBehavior`] to a [`ComponentCloneFn`]. If [`ComponentCloneBehavior::Default`] is
/// specified, the given `default` function will be used.
pub fn resolve(&self, default: ComponentCloneFn) -> ComponentCloneFn {
match self {
ComponentCloneBehavior::Default => default,
ComponentCloneBehavior::Ignore => component_clone_ignore,
ComponentCloneBehavior::Custom(custom) => *custom,
}
}
}
/// A queued component registration.
struct QueuedRegistration {
registrator: Box<dyn FnOnce(&mut ComponentsRegistrator, ComponentId, ComponentDescriptor)>,
@ -2885,165 +2841,3 @@ pub fn enforce_no_required_components_recursion(
}
}
}
/// Component [clone handler function](ComponentCloneFn) implemented using the [`Clone`] trait.
/// Can be [set](Component::clone_behavior) as clone handler for the specific component it is implemented for.
/// It will panic if set as handler for any other component.
///
pub fn component_clone_via_clone<C: Clone + Component>(
source: &SourceComponent,
ctx: &mut ComponentCloneCtx,
) {
if let Some(component) = source.read::<C>() {
ctx.write_target_component(component.clone());
}
}
/// Component [clone handler function](ComponentCloneFn) implemented using reflect.
/// Can be [set](Component::clone_behavior) as clone handler for any registered component,
/// but only reflected components will be cloned.
///
/// To clone a component using this handler, the following must be true:
/// - World has [`AppTypeRegistry`](crate::reflect::AppTypeRegistry)
/// - Component has [`TypeId`]
/// - Component is registered
/// - Component has [`ReflectFromPtr`](bevy_reflect::ReflectFromPtr) registered
/// - Component can be cloned via [`PartialReflect::reflect_clone`] _or_ has one of the following registered: [`ReflectFromReflect`](bevy_reflect::ReflectFromReflect),
/// [`ReflectDefault`](bevy_reflect::std_traits::ReflectDefault), [`ReflectFromWorld`](crate::reflect::ReflectFromWorld)
///
/// If any of the conditions is not satisfied, the component will be skipped.
///
/// See [`EntityClonerBuilder`](crate::entity::EntityClonerBuilder) for details.
///
/// [`PartialReflect::reflect_clone`]: bevy_reflect::PartialReflect::reflect_clone
#[cfg(feature = "bevy_reflect")]
pub fn component_clone_via_reflect(source: &SourceComponent, ctx: &mut ComponentCloneCtx) {
let Some(app_registry) = ctx.type_registry().cloned() else {
return;
};
let registry = app_registry.read();
let Some(source_component_reflect) = source.read_reflect(&registry) else {
return;
};
let component_info = ctx.component_info();
// checked in read_source_component_reflect
let type_id = component_info.type_id().unwrap();
// Try to clone using `reflect_clone`
if let Ok(mut component) = source_component_reflect.reflect_clone() {
if let Some(reflect_component) =
registry.get_type_data::<crate::reflect::ReflectComponent>(type_id)
{
reflect_component.map_entities(&mut *component, ctx.entity_mapper());
}
drop(registry);
ctx.write_target_component_reflect(component);
return;
}
// Try to clone using ReflectFromReflect
if let Some(reflect_from_reflect) =
registry.get_type_data::<bevy_reflect::ReflectFromReflect>(type_id)
{
if let Some(mut component) =
reflect_from_reflect.from_reflect(source_component_reflect.as_partial_reflect())
{
if let Some(reflect_component) =
registry.get_type_data::<crate::reflect::ReflectComponent>(type_id)
{
reflect_component.map_entities(&mut *component, ctx.entity_mapper());
}
drop(registry);
ctx.write_target_component_reflect(component);
return;
}
}
// Else, try to clone using ReflectDefault
if let Some(reflect_default) =
registry.get_type_data::<bevy_reflect::std_traits::ReflectDefault>(type_id)
{
let mut component = reflect_default.default();
component.apply(source_component_reflect.as_partial_reflect());
drop(registry);
ctx.write_target_component_reflect(component);
return;
}
// Otherwise, try to clone using ReflectFromWorld
if let Some(reflect_from_world) =
registry.get_type_data::<crate::reflect::ReflectFromWorld>(type_id)
{
let reflect_from_world = reflect_from_world.clone();
let source_component_cloned = source_component_reflect.to_dynamic();
let component_layout = component_info.layout();
let target = ctx.target();
let component_id = ctx.component_id();
drop(registry);
ctx.queue_deferred(move |world: &mut World, mapper: &mut dyn EntityMapper| {
let mut component = reflect_from_world.from_world(world);
assert_eq!(type_id, (*component).type_id());
component.apply(source_component_cloned.as_partial_reflect());
if let Some(reflect_component) = app_registry
.read()
.get_type_data::<crate::reflect::ReflectComponent>(type_id)
{
reflect_component.map_entities(&mut *component, mapper);
}
// SAFETY:
// - component_id is from the same world as target entity
// - component is a valid value represented by component_id
unsafe {
let raw_component_ptr =
core::ptr::NonNull::new_unchecked(Box::into_raw(component).cast::<u8>());
world
.entity_mut(target)
.insert_by_id(component_id, OwningPtr::new(raw_component_ptr));
if component_layout.size() > 0 {
// Ensure we don't attempt to deallocate zero-sized components
alloc::alloc::dealloc(raw_component_ptr.as_ptr(), component_layout);
}
}
});
}
}
/// Noop implementation of component clone handler function.
///
/// See [`EntityClonerBuilder`](crate::entity::EntityClonerBuilder) for details.
pub fn component_clone_ignore(_source: &SourceComponent, _ctx: &mut ComponentCloneCtx) {}
/// Wrapper for components clone specialization using autoderef.
#[doc(hidden)]
pub struct DefaultCloneBehaviorSpecialization<T>(PhantomData<T>);
impl<T> Default for DefaultCloneBehaviorSpecialization<T> {
fn default() -> Self {
Self(PhantomData)
}
}
/// Base trait for components clone specialization using autoderef.
#[doc(hidden)]
pub trait DefaultCloneBehaviorBase {
fn default_clone_behavior(&self) -> ComponentCloneBehavior;
}
impl<C> DefaultCloneBehaviorBase for DefaultCloneBehaviorSpecialization<C> {
fn default_clone_behavior(&self) -> ComponentCloneBehavior {
ComponentCloneBehavior::Default
}
}
/// Specialized trait for components clone specialization using autoderef.
#[doc(hidden)]
pub trait DefaultCloneBehaviorViaClone {
fn default_clone_behavior(&self) -> ComponentCloneBehavior;
}
impl<C: Clone + Component> DefaultCloneBehaviorViaClone for &DefaultCloneBehaviorSpecialization<C> {
fn default_clone_behavior(&self) -> ComponentCloneBehavior {
ComponentCloneBehavior::clone::<C>()
}
}