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Split PluginItem into separate structs per variant
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Make constructors + builders for the structs
Move more things out of proc-macros and into struct constructors/builders
Rework the safety invariants of `godot_dyn`
Document lots of these apis better
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@lilizoey
lilizoey committed Jan 6, 2025
1 parent b619959 commit 7848d18
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Showing 11 changed files with 595 additions and 455 deletions.
3 changes: 3 additions & 0 deletions godot-core/src/builder/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,9 @@ use std::marker::PhantomData;

mod method;

/// Class builder to store state for registering a class with Godot.
///
/// In the future this will be used, but for now it's a dummy struct.
pub struct ClassBuilder<C> {
_c: PhantomData<C>,
}
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3 changes: 2 additions & 1 deletion godot-core/src/private.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,8 @@ pub use crate::gen::classes::class_macros;
pub use crate::obj::rtti::ObjectRtti;
pub use crate::registry::callbacks;
pub use crate::registry::plugin::{
ClassPlugin, ErasedDynGd, ErasedRegisterFn, ErasedRegisterRpcsFn, InherentImpl, PluginItem,
ClassPlugin, DynTraitImpl, ErasedDynGd, ErasedRegisterFn, ITraitImpl, InherentImpl, PluginItem,
Struct,
};
pub use crate::storage::{as_storage, Storage};
pub use sys::out;
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22 changes: 21 additions & 1 deletion godot-core/src/registry/callbacks.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,9 @@

use crate::builder::ClassBuilder;
use crate::builtin::{StringName, Variant};
use crate::obj::{cap, Base, GodotClass, UserClass};
use crate::classes::Object;
use crate::obj::{bounds, cap, AsDyn, Base, Bounds, Gd, GodotClass, Inherits, UserClass};
use crate::registry::plugin::ErasedDynGd;
use crate::storage::{as_storage, InstanceStorage, Storage, StorageRefCounted};
use godot_ffi as sys;
use std::any::Any;
Expand Down Expand Up @@ -401,3 +403,21 @@ pub fn register_user_methods_constants<T: cap::ImplementsGodotApi>(_class_builde
pub fn register_user_rpcs<T: cap::ImplementsGodotApi>(object: &mut dyn Any) {
T::__register_rpcs(object);
}

/// # Safety
///
/// `obj` must be castable to `T`.
pub unsafe fn dynify_fn<T, D>(obj: Gd<Object>) -> ErasedDynGd
where
T: GodotClass + Inherits<Object> + AsDyn<D> + Bounds<Declarer = bounds::DeclUser>,
D: ?Sized + 'static,
{
// SAFETY: `obj` is castable to `T`.
let obj = unsafe { obj.try_cast::<T>().unwrap_unchecked() };
let obj = obj.into_dyn::<D>();
let obj = obj.upcast::<Object>();

ErasedDynGd {
boxed: Box::new(obj),
}
}
80 changes: 28 additions & 52 deletions godot-core/src/registry/class.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,8 @@ use crate::meta::ClassName;
use crate::obj::{cap, DynGd, Gd, GodotClass};
use crate::private::{ClassPlugin, PluginItem};
use crate::registry::callbacks;
use crate::registry::plugin::{ErasedDynifyFn, ErasedRegisterFn, InherentImpl};
use crate::{classes, godot_error, sys};
use crate::registry::plugin::{DynTraitImpl, ErasedRegisterFn, ITraitImpl, InherentImpl, Struct};
use crate::{godot_error, sys};
use sys::{interface_fn, out, Global, GlobalGuard, GlobalLockError};

/// Returns a lock to a global map of loaded classes, by initialization level.
Expand Down Expand Up @@ -43,9 +43,8 @@ fn global_loaded_classes_by_name() -> GlobalGuard<'static, HashMap<ClassName, Cl
lock_or_panic(&LOADED_CLASSES_BY_NAME, "loaded classes (by name)")
}

fn global_dyn_traits_by_typeid(
) -> GlobalGuard<'static, HashMap<any::TypeId, Vec<DynToClassRelation>>> {
static DYN_TRAITS_BY_TYPEID: Global<HashMap<any::TypeId, Vec<DynToClassRelation>>> =
fn global_dyn_traits_by_typeid() -> GlobalGuard<'static, HashMap<any::TypeId, Vec<DynTraitImpl>>> {
static DYN_TRAITS_BY_TYPEID: Global<HashMap<any::TypeId, Vec<DynTraitImpl>>> =
Global::default();

lock_or_panic(&DYN_TRAITS_BY_TYPEID, "dyn traits")
Expand All @@ -66,12 +65,6 @@ pub struct LoadedClass {
// Currently empty, but should already work for per-class queries.
pub struct ClassMetadata {}

/// Represents a `dyn Trait` implemented (and registered) for a class.
pub struct DynToClassRelation {
implementing_class_name: ClassName,
erased_dynify_fn: ErasedDynifyFn,
}

// ----------------------------------------------------------------------------------------------------------------------------------------------

// This works as long as fields are called the same. May still need individual #[cfg]s for newer fields.
Expand Down Expand Up @@ -111,7 +104,7 @@ struct ClassRegistrationInfo {
is_editor_plugin: bool,

/// One entry for each `dyn Trait` implemented (and registered) for this class.
dynify_fns_by_trait: HashMap<any::TypeId, ErasedDynifyFn>,
dynify_fns_by_trait: HashMap<any::TypeId, DynTraitImpl>,

/// Used to ensure that each component is only filled once.
component_already_filled: [bool; 4],
Expand Down Expand Up @@ -233,14 +226,11 @@ pub fn auto_register_classes(init_level: InitLevel) {
let metadata = ClassMetadata {};

// Transpose Class->Trait relations to Trait->Class relations.
for (trait_type_id, dynify_fn) in info.dynify_fns_by_trait.drain() {
for (trait_type_id, dyn_trait_impl) in info.dynify_fns_by_trait.drain() {
dyn_traits_by_typeid
.entry(trait_type_id)
.or_default()
.push(DynToClassRelation {
implementing_class_name: class_name,
erased_dynify_fn: dynify_fn,
});
.push(dyn_trait_impl);
}

loaded_classes_by_level
Expand Down Expand Up @@ -289,15 +279,16 @@ pub fn auto_register_rpcs<T: GodotClass>(object: &mut T) {
}
}

/// Tries to upgrade a polymorphic `Gd<T>` to `DynGd<T, D>`, where the `T` -> `D` relation is only present via derived objects.
/// Tries to convert a `Gd<T>` to a `DynGd<T, D>` for some class `T` and trait object `D`, where the trait may only be implemented for
/// some subclass of `T`.
///
/// This works without direct `T: AsDyn<D>` because it considers `object`'s dynamic type `Td : Inherits<T>`.
/// This works even when `T` doesn't implement `AsDyn<D>`, as long as the dynamic class of `object` implements `AsDyn<D>`.
///
/// Only direct relations are considered, i.e. the `Td: AsDyn<D>` must be fulfilled (and registered). If any intermediate base class of `Td`
/// implements the trait `D`, this will not consider it. Base-derived conversions are theoretically possible, but need quite a bit of extra
/// machinery.
/// This only looks for an `AsDyn<D>` implementation in the dynamic class, the conversion will fail if the dynamic class doesn't
/// implement `AsDyn<D>` even if there exists some superclass that does implement `AsDyn<D>`. This restriction could in theory be
/// lifted, but would need quite a bit of extra machinery to work.
pub(crate) fn try_dynify_object<T: GodotClass, D: ?Sized + 'static>(
object: Gd<T>,
mut object: Gd<T>,
) -> Result<DynGd<T, D>, ConvertError> {
let typeid = any::TypeId::of::<D>();
let trait_name = sys::short_type_name::<D>();
Expand All @@ -310,28 +301,16 @@ pub(crate) fn try_dynify_object<T: GodotClass, D: ?Sized + 'static>(

// TODO maybe use 2nd hashmap instead of linear search.
// (probably not pair of typeid/classname, as that wouldn't allow the above check).
let dynamic_class = object.dynamic_class_string();

for relation in relations {
if dynamic_class == relation.implementing_class_name.to_string_name() {
let erased = (relation.erased_dynify_fn)(object.upcast_object());

// Must succeed, or was registered wrong.
let dyn_gd_object = erased.boxed.downcast::<DynGd<classes::Object, D>>();

// SAFETY: the relation ensures that the **unified** (for storage) pointer was of type `DynGd<classes::Object, D>`.
let dyn_gd_object = unsafe { dyn_gd_object.unwrap_unchecked() };

// SAFETY: the relation ensures that the **original** pointer was of type `DynGd<T, D>`.
let dyn_gd_t = unsafe { dyn_gd_object.cast_unchecked::<T>() };

return Ok(dyn_gd_t);
match relation.get_dyn_gd(object) {
Ok(dyn_gd) => return Ok(dyn_gd),
Err(obj) => object = obj,
}
}

let error = FromGodotError::UnimplementedDynTrait {
trait_name,
class_name: dynamic_class.to_string(),
class_name: object.dynamic_class_string().to_string(),
};

Err(error.into_error(object))
Expand All @@ -344,7 +323,7 @@ fn fill_class_info(item: PluginItem, c: &mut ClassRegistrationInfo) {
// out!("| reg (before): {c:?}");
// out!("| comp: {component:?}");
match item {
PluginItem::Struct {
PluginItem::Struct(Struct {
base_class_name,
generated_create_fn,
generated_recreate_fn,
Expand All @@ -357,7 +336,7 @@ fn fill_class_info(item: PluginItem, c: &mut ClassRegistrationInfo) {
is_instantiable,
#[cfg(all(since_api = "4.3", feature = "register-docs"))]
docs: _,
} => {
}) => {
c.parent_class_name = Some(base_class_name);
c.default_virtual_fn = default_get_virtual_fn;
c.register_properties_fn = Some(register_properties_fn);
Expand Down Expand Up @@ -414,7 +393,7 @@ fn fill_class_info(item: PluginItem, c: &mut ClassRegistrationInfo) {
c.register_methods_constants_fn = Some(register_methods_constants_fn);
}

PluginItem::ITraitImpl {
PluginItem::ITraitImpl(ITraitImpl {
user_register_fn,
user_create_fn,
user_recreate_fn,
Expand All @@ -429,7 +408,7 @@ fn fill_class_info(item: PluginItem, c: &mut ClassRegistrationInfo) {
user_property_get_revert_fn,
#[cfg(all(since_api = "4.3", feature = "register-docs"))]
virtual_method_docs: _,
} => {
}) => {
c.user_register_fn = user_register_fn;

// The following unwraps of fill_into() shouldn't panic, since rustc will error if there are
Expand All @@ -453,20 +432,17 @@ fn fill_class_info(item: PluginItem, c: &mut ClassRegistrationInfo) {
c.godot_params.free_property_list_func = user_free_property_list_fn;
c.godot_params.property_can_revert_func = user_property_can_revert_fn;
c.godot_params.property_get_revert_func = user_property_get_revert_fn;
c.user_virtual_fn = Some(get_virtual_fn);
c.user_virtual_fn = get_virtual_fn;
}
PluginItem::DynTraitImpl {
dyn_trait_typeid,
erased_dynify_fn,
} => {
let prev = c
.dynify_fns_by_trait
.insert(dyn_trait_typeid, erased_dynify_fn);
PluginItem::DynTraitImpl(dyn_trait_impl) => {
let type_id = *dyn_trait_impl.dyn_trait_typeid();

let prev = c.dynify_fns_by_trait.insert(type_id, dyn_trait_impl);

assert!(
prev.is_none(),
"Duplicate registration of {:?} for class {}",
dyn_trait_typeid,
type_id,
c.class_name
);
}
Expand Down
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