Some more woogaloo around action dispatch

Co-authored-by: Conrad <conrad@zed.dev>

crates/gpui2/src/action.rs

@@ -114,6 +114,7 @@ lazy_static! {
 #[derive(Default)]
 struct ActionRegistry {
     builders_by_name: HashMap<SharedString, ActionBuilder>,
+    builders_by_type_id: HashMap<TypeId, ActionBuilder>,
     all_names: Vec<SharedString>, // So we can return a static slice.
 }
 
@@ -122,9 +123,22 @@ pub fn register_action<A: Action>() {
     let name = A::qualified_name();
     let mut lock = ACTION_REGISTRY.write();
     lock.builders_by_name.insert(name.clone(), A::build);
+    lock.builders_by_type_id.insert(TypeId::of::<A>(), A::build);
     lock.all_names.push(name);
 }
 
+/// Construct an action based on its name and optional JSON parameters sourced from the keymap.
+pub fn build_action_from_type(type_id: &TypeId) -> Result<Box<dyn Action>> {
+    let lock = ACTION_REGISTRY.read();
+
+    let build_action = lock
+        .builders_by_type_id
+        .get(type_id)
+        .ok_or_else(|| anyhow!("no action type registered for {:?}", type_id))?;
+
+    (build_action)(None)
+}
+
 /// Construct an action based on its name and optional JSON parameters sourced from the keymap.
 pub fn build_action(name: &str, params: Option<serde_json::Value>) -> Result<Box<dyn Action>> {
     let lock = ACTION_REGISTRY.read();