WIP

crates/gpui2/src/app/entity_map.rs

@@ -1,4 +1,4 @@
-use crate::{AnyBox, AppContext, Context};
+use crate::{AnyBox, AppContext, Context, EntityHandle};
 use anyhow::{anyhow, Result};
 use derive_more::{Deref, DerefMut};
 use parking_lot::{RwLock, RwLockUpgradableReadGuard};
@@ -329,7 +329,26 @@ impl<T> Eq for Handle<T> {}
 
 impl<T> PartialEq<WeakHandle<T>> for Handle<T> {
     fn eq(&self, other: &WeakHandle<T>) -> bool {
-        self.entity_id() == other.entity_id()
+        self.entity_id == other.entity_id
+    }
+}
+
+impl<T: 'static> EntityHandle<T> for Handle<T> {
+    type Weak = WeakHandle<T>;
+
+    fn entity_id(&self) -> EntityId {
+        self.entity_id
+    }
+
+    fn downgrade(&self) -> Self::Weak {
+        self.downgrade()
+    }
+
+    fn upgrade_from(weak: &Self::Weak) -> Option<Self>
+    where
+        Self: Sized,
+    {
+        weak.upgrade()
     }
 }
 
@@ -457,6 +476,6 @@ impl<T> Eq for WeakHandle<T> {}
 
 impl<T> PartialEq<Handle<T>> for WeakHandle<T> {
     fn eq(&self, other: &Handle<T>) -> bool {
-        self.entity_id() == other.entity_id()
+        self.entity_id == other.entity_id
     }
 }

crates/gpui2/src/gpui2.rs

@@ -106,6 +106,16 @@ pub trait VisualContext: Context {
     ) -> Self::Result<R>;
 }
 
+pub trait EntityHandle<T> {
+    type Weak: 'static + Send;
+
+    fn entity_id(&self) -> EntityId;
+    fn downgrade(&self) -> Self::Weak;
+    fn upgrade_from(weak: &Self::Weak) -> Option<Self>
+    where
+        Self: Sized;
+}
+
 pub enum GlobalKey {
     Numeric(usize),
     View(EntityId),

crates/gpui2/src/view.rs

@@ -1,7 +1,7 @@
 use crate::{
-    AnyBox, AnyElement, AvailableSpace, BorrowWindow, Bounds, Component, Element, ElementId,
-    EntityId, Flatten, Handle, LayoutId, Pixels, Size, ViewContext, VisualContext, WeakHandle,
-    WindowContext,
+    AnyBox, AnyElement, AppContext, AvailableSpace, BorrowWindow, Bounds, Component, Element,
+    ElementId, EntityHandle, EntityId, Flatten, Handle, LayoutId, Pixels, Size, ViewContext,
+    VisualContext, WeakHandle, WindowContext,
 };
 use anyhow::{Context, Result};
 use parking_lot::Mutex;
@@ -31,9 +31,7 @@ impl<V: 'static> View<V> {
             )),
         }
     }
-}
 
-impl<V: 'static> View<V> {
     pub fn into_any(self) -> AnyView {
         AnyView(Arc::new(self))
     }
@@ -44,9 +42,7 @@ impl<V: 'static> View<V> {
             render: Arc::downgrade(&self.render),
         }
     }
-}
 
-impl<V: 'static> View<V> {
     pub fn update<C, R>(
         &self,
         cx: &mut C,
@@ -58,11 +54,8 @@ impl<V: 'static> View<V> {
         cx.update_view(self, f)
     }
 
-    pub fn read<C>(&self, cx: &mut C) -> &V
-    where
-        C: VisualContext,
-    {
-        todo!()
+    pub fn read<'a>(&self, cx: &'a AppContext) -> &'a V {
+        cx.entities.read(&self.state)
     }
 }
 
@@ -124,6 +117,25 @@ impl<V: 'static> Element<()> for View<V> {
     }
 }
 
+impl<T: 'static> EntityHandle<T> for View<T> {
+    type Weak = WeakView<T>;
+
+    fn entity_id(&self) -> EntityId {
+        self.state.entity_id
+    }
+
+    fn downgrade(&self) -> Self::Weak {
+        self.downgrade()
+    }
+
+    fn upgrade_from(weak: &Self::Weak) -> Option<Self>
+    where
+        Self: Sized,
+    {
+        weak.upgrade()
+    }
+}
+
 pub struct WeakView<V> {
     pub(crate) state: WeakHandle<V>,
     render: Weak<Mutex<dyn Fn(&mut V, &mut ViewContext<V>) -> AnyElement<V> + Send + 'static>>,

crates/gpui2/src/window.rs

@@ -1,14 +1,14 @@
 use crate::{
     px, size, Action, AnyBox, AnyDrag, AnyView, AppContext, AsyncWindowContext, AvailableSpace,
     Bounds, BoxShadow, Context, Corners, DevicePixels, DispatchContext, DisplayId, Edges, Effect,
-    EntityId, EventEmitter, ExternalPaths, FileDropEvent, FocusEvent, FontId, GlobalElementId,
-    GlyphId, Handle, Hsla, ImageData, InputEvent, IsZero, KeyListener, KeyMatch, KeyMatcher,
-    Keystroke, LayoutId, MainThread, MainThreadOnly, ModelContext, Modifiers, MonochromeSprite,
-    MouseButton, MouseDownEvent, MouseMoveEvent, MouseUpEvent, Path, Pixels, PlatformAtlas,
-    PlatformWindow, Point, PolychromeSprite, Quad, Reference, RenderGlyphParams, RenderImageParams,
-    RenderSvgParams, ScaledPixels, SceneBuilder, Shadow, SharedString, Size, Style, Subscription,
-    TaffyLayoutEngine, Task, Underline, UnderlineStyle, View, VisualContext, WeakHandle, WeakView,
-    WindowOptions, SUBPIXEL_VARIANTS,
+    EntityHandle, EntityId, EventEmitter, ExternalPaths, FileDropEvent, FocusEvent, FontId,
+    GlobalElementId, GlyphId, Handle, Hsla, ImageData, InputEvent, IsZero, KeyListener, KeyMatch,
+    KeyMatcher, Keystroke, LayoutId, MainThread, MainThreadOnly, ModelContext, Modifiers,
+    MonochromeSprite, MouseButton, MouseDownEvent, MouseMoveEvent, MouseUpEvent, Path, Pixels,
+    PlatformAtlas, PlatformWindow, Point, PolychromeSprite, Quad, Reference, RenderGlyphParams,
+    RenderImageParams, RenderSvgParams, ScaledPixels, SceneBuilder, Shadow, SharedString, Size,
+    Style, Subscription, TaffyLayoutEngine, Task, Underline, UnderlineStyle, View, VisualContext,
+    WeakHandle, WeakView, WindowOptions, SUBPIXEL_VARIANTS,
 };
 use anyhow::Result;
 use collections::HashMap;
@@ -376,6 +376,35 @@ impl<'a, 'w> WindowContext<'a, 'w> {
         self.notify();
     }
 
+    pub fn subscribe<E, H>(
+        &mut self,
+        handle: &H,
+        mut on_event: impl FnMut(H, &E::Event, &mut WindowContext<'_, '_>) + Send + 'static,
+    ) -> Subscription
+    where
+        E: EventEmitter,
+        H: EntityHandle<E>,
+    {
+        let entity_id = handle.entity_id();
+        let handle = handle.downgrade();
+        let window_handle = self.window.handle;
+        self.app.event_listeners.insert(
+            entity_id,
+            Box::new(move |event, cx| {
+                cx.update_window(window_handle, |cx| {
+                    if let Some(handle) = H::upgrade_from(&handle) {
+                        let event = event.downcast_ref().expect("invalid event type");
+                        on_event(handle, event, cx);
+                        true
+                    } else {
+                        false
+                    }
+                })
+                .unwrap_or(false)
+            }),
+        )
+    }
+
     /// Schedule the given closure to be run on the main thread. It will be invoked with
     /// a `MainThread<WindowContext>`, which provides access to platform-specific functionality
     /// of the window.
@@ -1600,21 +1629,24 @@ impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
         )
     }
 
-    pub fn subscribe<E: EventEmitter>(
+    pub fn subscribe<E, H>(
         &mut self,
-        handle: &Handle<E>,
-        mut on_event: impl FnMut(&mut V, Handle<E>, &E::Event, &mut ViewContext<'_, '_, V>)
-            + Send
-            + 'static,
-    ) -> Subscription {
+        handle: &H,
+        mut on_event: impl FnMut(&mut V, H, &E::Event, &mut ViewContext<'_, '_, V>) + Send + 'static,
+    ) -> Subscription
+    where
+        E: EventEmitter,
+        H: EntityHandle<E>,
+    {
         let view = self.view();
+        let entity_id = handle.entity_id();
         let handle = handle.downgrade();
         let window_handle = self.window.handle;
         self.app.event_listeners.insert(
-            handle.entity_id,
+            entity_id,
             Box::new(move |event, cx| {
                 cx.update_window(window_handle, |cx| {
-                    if let Some(handle) = handle.upgrade() {
+                    if let Some(handle) = H::upgrade_from(&handle) {
                         let event = event.downcast_ref().expect("invalid event type");
                         view.update(cx, |this, cx| on_event(this, handle, event, cx))
                             .is_ok()