
# Objective Right now, `TypeInfo` can be accessed directly from a type using either `Typed::type_info` or `Reflect::get_represented_type_info`. However, once that `TypeInfo` is accessed, any nested types must be accessed via the `TypeRegistry`. ```rust #[derive(Reflect)] struct Foo { bar: usize } let registry = TypeRegistry::default(); let TypeInfo::Struct(type_info) = Foo::type_info() else { panic!("expected struct info"); }; let field = type_info.field("bar").unwrap(); let field_info = registry.get_type_info(field.type_id()).unwrap(); assert!(field_info.is::<usize>());; ``` ## Solution Enable nested types within a `TypeInfo` to be retrieved directly. ```rust #[derive(Reflect)] struct Foo { bar: usize } let TypeInfo::Struct(type_info) = Foo::type_info() else { panic!("expected struct info"); }; let field = type_info.field("bar").unwrap(); let field_info = field.type_info().unwrap(); assert!(field_info.is::<usize>());; ``` The particular implementation was chosen for two reasons. Firstly, we can't just store `TypeInfo` inside another `TypeInfo` directly. This is because some types are recursive and would result in a deadlock when trying to create the `TypeInfo` (i.e. it has to create the `TypeInfo` before it can use it, but it also needs the `TypeInfo` before it can create it). Therefore, we must instead store the function so it can be retrieved lazily. I had considered also using a `OnceLock` or something to lazily cache the info, but I figured we can look into optimizations later. The API should remain the same with or without the `OnceLock`. Secondly, a new wrapper trait had to be introduced: `MaybeTyped`. Like `RegisterForReflection`, this trait is `#[doc(hidden)]` and only exists so that we can properly handle dynamic type fields without requiring them to implement `Typed`. We don't want dynamic types to implement `Typed` due to the fact that it would make the return type `Option<&'static TypeInfo>` for all types even though only the dynamic types ever need to return `None` (see #6971 for details). Users should never have to interact with this trait as it has a blanket impl for all `Typed` types. And `Typed` is automatically implemented when deriving `Reflect` (as it is required). The one downside is we do need to return `Option<&'static TypeInfo>` from all these new methods so that we can handle the dynamic cases. If we didn't have to, we'd be able to get rid of the `Option` entirely. But I think that's an okay tradeoff for this one part of the API, and keeps the other APIs intact. ## Testing This PR contains tests to verify everything works as expected. You can test locally by running: ``` cargo test --package bevy_reflect ``` --- ## Changelog ### Public Changes - Added `ArrayInfo::item_info` method - Added `NamedField::type_info` method - Added `UnnamedField::type_info` method - Added `ListInfo::item_info` method - Added `MapInfo::key_info` method - Added `MapInfo::value_info` method - All active fields now have a `Typed` bound (remember that this is automatically satisfied for all types that derive `Reflect`) ### Internal Changes - Added `MaybeTyped` trait ## Migration Guide All active fields for reflected types (including lists, maps, tuples, etc.), must implement `Typed`. For the majority of users this won't have any visible impact. However, users implementing `Reflect` manually may need to update their types to implement `Typed` if they weren't already. Additionally, custom dynamic types will need to implement the new hidden `MaybeTyped` trait.
192 lines
5.3 KiB
Rust
192 lines
5.3 KiB
Rust
use bevy_reflect_derive::impl_type_path;
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use smallvec::{Array as SmallArray, SmallVec};
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use std::any::Any;
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use crate::utility::GenericTypeInfoCell;
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use crate::{
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self as bevy_reflect, ApplyError, FromReflect, FromType, GetTypeRegistration, List, ListInfo,
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ListIter, MaybeTyped, Reflect, ReflectFromPtr, ReflectKind, ReflectMut, ReflectOwned,
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ReflectRef, TypeInfo, TypePath, TypeRegistration, Typed,
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};
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impl<T: SmallArray + TypePath + Send + Sync> List for SmallVec<T>
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where
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T::Item: FromReflect + MaybeTyped + TypePath,
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{
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fn get(&self, index: usize) -> Option<&dyn Reflect> {
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if index < SmallVec::len(self) {
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Some(&self[index] as &dyn Reflect)
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} else {
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None
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}
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}
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fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {
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if index < SmallVec::len(self) {
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Some(&mut self[index] as &mut dyn Reflect)
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} else {
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None
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}
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}
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fn insert(&mut self, index: usize, value: Box<dyn Reflect>) {
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let value = value.take::<T::Item>().unwrap_or_else(|value| {
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<T as SmallArray>::Item::from_reflect(&*value).unwrap_or_else(|| {
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panic!(
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"Attempted to insert invalid value of type {}.",
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value.reflect_type_path()
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)
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})
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});
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SmallVec::insert(self, index, value);
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}
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fn remove(&mut self, index: usize) -> Box<dyn Reflect> {
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Box::new(self.remove(index))
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}
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fn push(&mut self, value: Box<dyn Reflect>) {
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let value = value.take::<T::Item>().unwrap_or_else(|value| {
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<T as SmallArray>::Item::from_reflect(&*value).unwrap_or_else(|| {
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panic!(
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"Attempted to push invalid value of type {}.",
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value.reflect_type_path()
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)
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})
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});
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SmallVec::push(self, value);
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}
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fn pop(&mut self) -> Option<Box<dyn Reflect>> {
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self.pop().map(|value| Box::new(value) as Box<dyn Reflect>)
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}
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fn len(&self) -> usize {
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<SmallVec<T>>::len(self)
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}
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fn iter(&self) -> ListIter {
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ListIter::new(self)
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}
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fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {
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self.into_iter()
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.map(|value| Box::new(value) as Box<dyn Reflect>)
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.collect()
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}
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}
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impl<T: SmallArray + TypePath + Send + Sync> Reflect for SmallVec<T>
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where
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T::Item: FromReflect + MaybeTyped + TypePath,
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{
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fn get_represented_type_info(&self) -> Option<&'static TypeInfo> {
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Some(<Self as Typed>::type_info())
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}
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fn into_any(self: Box<Self>) -> Box<dyn Any> {
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self
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}
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fn as_any(&self) -> &dyn Any {
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self
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}
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fn as_any_mut(&mut self) -> &mut dyn Any {
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self
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}
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fn into_reflect(self: Box<Self>) -> Box<dyn Reflect> {
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self
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}
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fn as_reflect(&self) -> &dyn Reflect {
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self
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}
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fn as_reflect_mut(&mut self) -> &mut dyn Reflect {
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self
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}
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fn apply(&mut self, value: &dyn Reflect) {
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crate::list_apply(self, value);
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}
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fn try_apply(&mut self, value: &dyn Reflect) -> Result<(), ApplyError> {
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crate::list_try_apply(self, value)
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}
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fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>> {
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*self = value.take()?;
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Ok(())
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}
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fn reflect_kind(&self) -> ReflectKind {
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ReflectKind::List
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}
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fn reflect_ref(&self) -> ReflectRef {
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ReflectRef::List(self)
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}
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fn reflect_mut(&mut self) -> ReflectMut {
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ReflectMut::List(self)
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}
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fn reflect_owned(self: Box<Self>) -> ReflectOwned {
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ReflectOwned::List(self)
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}
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fn clone_value(&self) -> Box<dyn Reflect> {
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Box::new(self.clone_dynamic())
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}
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fn reflect_partial_eq(&self, value: &dyn Reflect) -> Option<bool> {
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crate::list_partial_eq(self, value)
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}
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}
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impl<T: SmallArray + TypePath + Send + Sync + 'static> Typed for SmallVec<T>
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where
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T::Item: FromReflect + MaybeTyped + TypePath,
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{
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fn type_info() -> &'static TypeInfo {
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static CELL: GenericTypeInfoCell = GenericTypeInfoCell::new();
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CELL.get_or_insert::<Self, _>(|| TypeInfo::List(ListInfo::new::<Self, T::Item>()))
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}
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}
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impl_type_path!(::smallvec::SmallVec<T: SmallArray>);
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impl<T: SmallArray + TypePath + Send + Sync> FromReflect for SmallVec<T>
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where
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T::Item: FromReflect + MaybeTyped + TypePath,
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{
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fn from_reflect(reflect: &dyn Reflect) -> Option<Self> {
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if let ReflectRef::List(ref_list) = reflect.reflect_ref() {
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let mut new_list = Self::with_capacity(ref_list.len());
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for field in ref_list.iter() {
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new_list.push(<T as SmallArray>::Item::from_reflect(field)?);
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}
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Some(new_list)
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} else {
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None
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}
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}
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}
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impl<T: SmallArray + TypePath + Send + Sync> GetTypeRegistration for SmallVec<T>
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where
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T::Item: FromReflect + MaybeTyped + TypePath,
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{
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fn get_type_registration() -> TypeRegistration {
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let mut registration = TypeRegistration::of::<SmallVec<T>>();
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registration.insert::<ReflectFromPtr>(FromType::<SmallVec<T>>::from_type());
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registration
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}
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}
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#[cfg(feature = "functions")]
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crate::func::macros::impl_function_traits!(SmallVec<T>; <T: SmallArray + TypePath + Send + Sync> where T::Item: FromReflect + MaybeTyped + TypePath);
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