learn how workspaces + proc macros work & restructure everything

core/src/util/handle.rs

@@ -0,0 +1,60 @@
+use std::{
+    cell::{Ref, RefCell, RefMut},
+    marker::Unsize,
+    ops::CoerceUnsized,
+    rc::{Rc, Weak},
+};
+
+pub struct Handle<T: ?Sized>(Rc<RefCell<T>>);
+pub struct WeakHandle<T: ?Sized>(Weak<RefCell<T>>);
+
+impl<T: ?Sized> Handle<T> {
+    pub fn get(&self) -> Ref<'_, T> {
+        self.0.borrow()
+    }
+
+    pub fn get_mut(&self) -> RefMut<'_, T> {
+        self.0.borrow_mut()
+    }
+
+    pub fn refs(&self) -> usize {
+        Rc::strong_count(&self.0)
+    }
+
+    pub fn weak(&self) -> WeakHandle<T> {
+        WeakHandle(Rc::downgrade(&self.0))
+    }
+}
+
+impl<T: ?Sized> WeakHandle<T> {
+    pub fn strong(&self) -> Option<Handle<T>> {
+        Some(Handle(self.0.upgrade()?))
+    }
+}
+
+impl<T: ?Sized> Clone for Handle<T> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<T: ?Sized> Clone for WeakHandle<T> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<T: Default> Default for Handle<T> {
+    fn default() -> Self {
+        Self(Default::default())
+    }
+}
+
+impl<T> From<T> for Handle<T> {
+    fn from(value: T) -> Self {
+        Self(Rc::new(RefCell::new(value)))
+    }
+}
+
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Handle<U>> for Handle<T> {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<WeakHandle<U>> for WeakHandle<T> {}