Add editor plugins, and registration of classes at the proper initialization level

godot-codegen/src/class_generator.rs

@@ -506,6 +506,7 @@ fn make_class(class: &Class, class_name: &TyName, ctx: &mut Context) -> Generate
 
     let constructor = make_constructor(class, ctx);
     let api_level = util::get_api_level(class);
+    let init_level = api_level.to_init_level();
 
     let FnDefinitions {
         functions: methods,
@@ -618,6 +619,7 @@ fn make_class(class: &Class, class_name: &TyName, ctx: &mut Context) -> Generate
                 type Base = #base_ty;
                 type Declarer = crate::obj::dom::EngineDomain;
                 type Mem = crate::obj::mem::#memory;
+                const INIT_LEVEL: Option<crate::init::InitLevel> = #init_level;
 
                 fn class_name() -> ClassName {
                     ClassName::from_ascii_cstr(#class_name_cstr)

godot-codegen/src/codegen_special_cases.rs

@@ -127,6 +127,7 @@ const SELECTED_CLASSES: &[&str] = &[
     "CollisionObject2D",
     "CollisionShape2D",
     "Control",
+    "EditorPlugin",
     "Engine",
     "FileAccess",
     "HTTPRequest",

godot-codegen/src/special_cases.rs

@@ -71,9 +71,15 @@ pub(crate) fn is_class_deleted(class_name: &TyName) -> bool {
 
     match class_name {
         // Hardcoded cases that are not accessible.
-        | "JavaClassWrapper" // only on Android.
-        | "JavaScriptBridge" // only on WASM.
-        | "ThemeDB" // lazily loaded; TODO enable this.
+        // Only on Android.
+        | "JavaClassWrapper"
+        | "JNISingleton"
+        | "JavaClass"
+        // Only on WASM.
+        | "JavaScriptBridge"
+        | "JavaScriptObject"
+        // lazily loaded; TODO enable this.
+        | "ThemeDB" 
 
         // Thread APIs.
         | "Thread"
@@ -124,7 +130,6 @@ fn is_class_experimental(class_name: &TyName) -> bool {
         | "NavigationRegion3D"
         | "NavigationServer2D"
         | "NavigationServer3D"
-        | "ProjectSettings"
         | "SkeletonModification2D"
         | "SkeletonModification2DCCDIK"
         | "SkeletonModification2DFABRIK"

godot-codegen/src/util.rs

@@ -66,6 +66,15 @@ impl ClassCodegenLevel {
             Self::Lazy => unreachable!("lazy classes should be deleted at the moment"),
         }
     }
+
+    pub fn to_init_level(self) -> TokenStream {
+        match self {
+            Self::Servers => quote! { Some(crate::init::InitLevel::Servers) },
+            Self::Scene => quote! { Some(crate::init::InitLevel::Scene) },
+            Self::Editor => quote! { Some(crate::init::InitLevel::Editor) },
+            Self::Lazy => quote! { None },
+        }
+    }
 }
 
 // ----------------------------------------------------------------------------------------------------------------------------------------------

godot-core/src/init/mod.rs

@@ -92,12 +92,12 @@ fn gdext_on_level_init(level: InitLevel) {
             }
             InitLevel::Scene => {
                 sys::load_class_method_table(sys::ClassApiLevel::Scene);
-                crate::auto_register_classes();
             }
             InitLevel::Editor => {
                 sys::load_class_method_table(sys::ClassApiLevel::Editor);
             }
         }
+        crate::auto_register_classes(level);
     }
 }
 

godot-core/src/lib.rs

@@ -168,6 +168,9 @@ pub mod private {
         use std::io::Write;
         std::io::stdout().flush().expect("flush stdout");
     }
+
+    /// Ensure `T` is an editor plugin.
+    pub const fn is_editor_plugin<T: crate::obj::Inherits<crate::engine::EditorPlugin>>() {}
 }
 
 macro_rules! generate_gdextension_api_version {

godot-core/src/obj/traits.rs

@@ -6,6 +6,7 @@
 
 use crate::builder::ClassBuilder;
 use crate::builtin::GodotString;
+use crate::init::InitLevel;
 use crate::obj::Base;
 
 use crate::builtin::meta::ClassName;
@@ -34,6 +35,12 @@ where
     /// Defines the memory strategy.
     type Mem: mem::Memory;
 
+    /// During which initialization level this class is available/should be initialized with Godot.
+    ///
+    /// Is `None` if the class has complicated initialization requirements, and generally cannot be inherited
+    /// from.
+    const INIT_LEVEL: Option<InitLevel>;
+
     /// The name of the class, under which it is registered in Godot.
     ///
     /// This may deviate from the Rust struct name: `HttpRequest::class_name().as_str() == "HTTPRequest"`.
@@ -60,6 +67,7 @@ unsafe impl GodotClass for () {
     type Base = ();
     type Declarer = dom::EngineDomain;
     type Mem = mem::ManualMemory;
+    const INIT_LEVEL: Option<InitLevel> = None;
 
     fn class_name() -> ClassName {
         ClassName::none()

godot-core/src/registry.rs

@@ -6,6 +6,8 @@
 
 #![allow(dead_code)] // FIXME
 
+use crate::init::InitLevel;
+use crate::log;
 use crate::obj::*;
 use crate::private::as_storage;
 use crate::storage::InstanceStorage;
@@ -29,6 +31,7 @@ use std::{fmt, ptr};
 pub struct ClassPlugin {
     pub class_name: ClassName,
     pub component: PluginComponent,
+    pub init_level: Option<InitLevel>,
 }
 
 /// Type-erased function object, holding a `register_class` function.
@@ -109,6 +112,9 @@ pub enum PluginComponent {
             p_name: sys::GDExtensionConstStringNamePtr,
         ) -> sys::GDExtensionClassCallVirtual,
     },
+
+    #[cfg(since_api = "4.1")]
+    EditorPlugin,
 }
 
 // ----------------------------------------------------------------------------------------------------------------------------------------------
@@ -120,6 +126,8 @@ struct ClassRegistrationInfo {
     generated_register_fn: Option<ErasedRegisterFn>,
     user_register_fn: Option<ErasedRegisterFn>,
     godot_params: sys::GDExtensionClassCreationInfo,
+    init_level: InitLevel,
+    is_editor_plugin: bool,
 }
 
 /// Registers a class with static type information.
@@ -128,7 +136,8 @@ pub fn register_class<
         + cap::ImplementsGodotVirtual
         + cap::GodotToString
         + cap::GodotNotification
-        + cap::GodotRegisterClass,
+        + cap::GodotRegisterClass
+        + GodotClass,
 >() {
     // TODO: provide overloads with only some trait impls
 
@@ -155,22 +164,33 @@ pub fn register_class<
             raw: callbacks::register_class_by_builder::<T>,
         }),
         godot_params,
+        init_level: T::INIT_LEVEL.unwrap_or_else(|| {
+            panic!("Unknown initialization level for class {}", T::class_name())
+        }),
+        is_editor_plugin: false,
     });
 }
 
 /// Lets Godot know about all classes that have self-registered through the plugin system.
-pub fn auto_register_classes() {
-    out!("Auto-register classes...");
+pub fn auto_register_classes(init_level: InitLevel) {
+    out!("Auto-register classes at level `{init_level:?}`...");
 
     // Note: many errors are already caught by the compiler, before this runtime validation even takes place:
     // * missing #[derive(GodotClass)] or impl GodotClass for T
     // * duplicate impl GodotInit for T
     //
-
     let mut map = HashMap::<ClassName, ClassRegistrationInfo>::new();
 
     crate::private::iterate_plugins(|elem: &ClassPlugin| {
         //out!("* Plugin: {elem:#?}");
+        match elem.init_level {
+            None => {
+                log::godot_error!("Unknown initialization level for class {}", elem.class_name);
+                return;
+            }
+            Some(elem_init_level) if elem_init_level != init_level => return,
+            _ => (),
+        }
 
         let name = elem.class_name;
         let class_info = map
@@ -183,11 +203,14 @@ pub fn auto_register_classes() {
     //out!("Class-map: {map:#?}");
 
     for info in map.into_values() {
-        out!("Register class:   {}", info.class_name);
+        out!(
+            "Register class:   {} at level `{init_level:?}`",
+            info.class_name
+        );
         register_class_raw(info);
     }
 
-    out!("All classes auto-registered.");
+    out!("All classes for level `{init_level:?}` auto-registered.");
 }
 
 /// Populate `c` with all the relevant data from `component` (depending on component type).
@@ -227,6 +250,10 @@ fn fill_class_info(component: PluginComponent, c: &mut ClassRegistrationInfo) {
             c.godot_params.notification_func = user_on_notification_fn;
             c.godot_params.get_virtual_func = Some(get_virtual_fn);
         }
+        #[cfg(since_api = "4.1")]
+        PluginComponent::EditorPlugin => {
+            c.is_editor_plugin = true;
+        }
     }
     // out!("|   reg (after):     {c:?}");
     // out!();
@@ -282,6 +309,13 @@ fn register_class_raw(info: ClassRegistrationInfo) {
     if let Some(register_fn) = info.user_register_fn {
         (register_fn.raw)(&mut class_builder);
     }
+
+    #[cfg(since_api = "4.1")]
+    if info.is_editor_plugin {
+        unsafe { interface_fn!(editor_add_plugin)(class_name.string_sys()) };
+    }
+    #[cfg(before_api = "4.1")]
+    assert!(!info.is_editor_plugin);
 }
 
 /// Callbacks that are passed as function pointers to Godot upon class registration.
@@ -444,6 +478,8 @@ fn default_registration_info(class_name: ClassName) -> ClassRegistrationInfo {
         generated_register_fn: None,
         user_register_fn: None,
         godot_params: default_creation_info(),
+        init_level: InitLevel::Scene,
+        is_editor_plugin: false,
     }
 }
 

godot-macros/src/class/derive_godot_class.rs

@@ -33,6 +33,20 @@ pub fn derive_godot_class(decl: Declaration) -> ParseResult<TokenStream> {
     let prv = quote! { ::godot::private };
     let godot_exports_impl = make_property_impl(class_name, &fields);
 
+    let editor_plugin = if struct_cfg.is_editor_plugin {
+        quote! {
+            ::godot::sys::plugin_add!(__GODOT_PLUGIN_REGISTRY in #prv; #prv::ClassPlugin {
+                class_name: #class_name_obj,
+                component: #prv::PluginComponent::EditorPlugin,
+                init_level: <#class_name as ::godot::obj::GodotClass>::INIT_LEVEL,
+            });
+
+            const _: () = #prv::is_editor_plugin::<#class_name>();
+        }
+    } else {
+        quote! {}
+    };
+
     let (godot_init_impl, create_fn);
     if struct_cfg.has_generated_init {
         godot_init_impl = make_godot_init_impl(class_name, fields);
@@ -49,6 +63,7 @@ pub fn derive_godot_class(decl: Declaration) -> ParseResult<TokenStream> {
             type Base = #base_class;
             type Declarer = ::godot::obj::dom::UserDomain;
             type Mem = <Self::Base as ::godot::obj::GodotClass>::Mem;
+            const INIT_LEVEL: Option<::godot::init::InitLevel> = <#base_class as ::godot::obj::GodotClass>::INIT_LEVEL;
 
             fn class_name() -> ::godot::builtin::meta::ClassName {
                 ::godot::builtin::meta::ClassName::from_ascii_cstr(#class_name_cstr)
@@ -66,8 +81,11 @@ pub fn derive_godot_class(decl: Declaration) -> ParseResult<TokenStream> {
                 generated_create_fn: #create_fn,
                 free_fn: #prv::callbacks::free::<#class_name>,
             },
+            init_level: <#class_name as ::godot::obj::GodotClass>::INIT_LEVEL,
         });
 
+        #editor_plugin
+
         #prv::class_macros::#inherits_macro!(#class_name);
     })
 }
@@ -89,6 +107,7 @@ fn parse_struct_attributes(class: &Struct) -> ParseResult<ClassAttributes> {
     let mut base_ty = ident("RefCounted");
     let mut has_generated_init = false;
     let mut is_tool = false;
+    let mut is_editor_plugin = false;
 
     // #[class] attribute on struct
     if let Some(mut parser) = KvParser::parse(&class.attributes, "class")? {
@@ -104,13 +123,19 @@ fn parse_struct_attributes(class: &Struct) -> ParseResult<ClassAttributes> {
             is_tool = true;
         }
 
+        // TODO: better error message when using in Godot 4.0
+        if parser.handle_alone_ident("editor_plugin")?.is_some() {
+            is_editor_plugin = true;
+        }
+
         parser.finish()?;
     }
 
     Ok(ClassAttributes {
         base_ty,
         has_generated_init,
         is_tool,
+        is_editor_plugin,
     })
 }
 
@@ -190,6 +215,7 @@ struct ClassAttributes {
     base_ty: Ident,
     has_generated_init: bool,
     is_tool: bool,
+    is_editor_plugin: bool,
 }
 
 fn make_godot_init_impl(class_name: &Ident, fields: Fields) -> TokenStream {

godot-macros/src/class/godot_api.rs

@@ -193,6 +193,7 @@ fn transform_inherent_impl(mut decl: Impl) -> Result<TokenStream, Error> {
                     raw: #prv::callbacks::register_user_binds::<#class_name>,
                 },
             },
+            init_level: <#class_name as ::godot::obj::GodotClass>::INIT_LEVEL,
         });
     };
 
@@ -505,6 +506,7 @@ fn transform_trait_impl(original_impl: Impl) -> Result<TokenStream, Error> {
                 user_on_notification_fn: #on_notification_fn,
                 get_virtual_fn: #prv::callbacks::get_virtual::<#class_name>,
             },
+            init_level: <#class_name as ::godot::obj::GodotClass>::INIT_LEVEL,
         });
     };
 

godot-macros/src/lib.rs

@@ -318,6 +318,20 @@ use crate::util::ident;
 /// for more information and further customization.
 ///
 /// This is very similar to [GDScript's `@tool` feature](https://docs.godotengine.org/en/stable/tutorials/plugins/running_code_in_the_editor.html).
+///
+/// # Editor Plugins
+///
+/// If you annotate a class with `#[class(editor_plugin)]`, it will be turned into an editor plugin. The
+/// class must then inherit from `EditorPlugin`, and an instance of that class will be automatically added
+/// to the editor when launched.
+///
+/// See [Godot's documentation of editor plugins](https://docs.godotengine.org/en/stable/tutorials/plugins/editor/index.html)
+/// for more information about editor plugins. But note that you do not need to create and enable the plugin
+/// through Godot's `Create New Plugin` menu for it to work, simply annotating the class with `editor_plugin`
+/// automatically enables it when the library is loaded.
+///
+/// This should usually be combined with `#[class(tool)]` so that the code you write will actually run in the
+/// editor.
 #[proc_macro_derive(GodotClass, attributes(class, base, var, export, init, signal))]
 pub fn derive_godot_class(input: TokenStream) -> TokenStream {
     translate(input, class::derive_godot_class)

godot-macros/src/util/kv_parser.rs

@@ -82,10 +82,16 @@ impl KvParser {
     /// Handles a key that can only occur without a value, e.g. `#[attr(toggle)]`. Returns whether
     /// the key is present.
     pub fn handle_alone(&mut self, key: &str) -> ParseResult<bool> {
-        match self.handle_any(key) {
-            None => Ok(false),
-            Some(value) => match value {
-                None => Ok(true),
+        self.handle_alone_ident(key).map(|id| id.is_some())
+    }
+
+    /// Handles a key that can only occur without a value, e.g. `#[attr(toggle)]`. Returns the key if it is
+    /// present.
+    pub fn handle_alone_ident(&mut self, key: &str) -> ParseResult<Option<Ident>> {
+        match self.handle_any_entry(key) {
+            None => Ok(None),
+            Some((id, value)) => match value {
+                None => Ok(Some(id)),
                 Some(value) => bail!(&value.tokens[0], "key `{key}` should not have a value"),
             },
         }