feat: add getCurrentRoute (facebook#8254)

Author: osdnk

packages/core/src/BaseNavigationContainer.tsx

@@ -199,6 +199,17 @@ const BaseNavigationContainer = React.forwardRef(
       return getStateForRoute('root');
     }, [getStateForRoute]);
 
+    const getCurrentRoute = React.useCallback(() => {
+      let state = getRootState();
+      if (state === undefined) {
+        return undefined;
+      }
+      while (state.routes[state.index].state !== undefined) {
+        state = state.routes[state.index].state as NavigationState;
+      }
+      return state.routes[state.index];
+    }, [getRootState]);
+
     const emitter = useEventEmitter();
 
     React.useImperativeHandle(ref, () => ({
@@ -221,6 +232,7 @@ const BaseNavigationContainer = React.forwardRef(
       getRootState,
       dangerouslyGetState: () => state,
       dangerouslyGetParent: () => undefined,
+      getCurrentRoute,
     }));
 
     const builderContext = React.useMemo(

packages/core/src/__tests__/index.test.tsx

@@ -1490,3 +1490,41 @@ it("doesn't throw if children is null", () => {
 
   expect(() => render(element).update(element)).not.toThrowError();
 });
+
+it('returns currently focused route with getCurrentRoute', () => {
+  const TestNavigator = (props: any): any => {
+    const { state, descriptors } = useNavigationBuilder(MockRouter, props);
+
+    return descriptors[state.routes[state.index].key].render();
+  };
+
+  const TestScreen = () => null;
+
+  const navigation = React.createRef<NavigationContainerRef>();
+
+  const container = (
+    <BaseNavigationContainer ref={navigation}>
+      <TestNavigator>
+        <Screen name="bar" options={{ a: 'b' }}>
+          {() => (
+            <TestNavigator initialRouteName="bar-a">
+              <Screen
+                name="bar-a"
+                component={TestScreen}
+                options={{ sample: 'data' }}
+              />
+            </TestNavigator>
+          )}
+        </Screen>
+        <Screen name="xux" component={TestScreen} />
+      </TestNavigator>
+    </BaseNavigationContainer>
+  );
+
+  render(container).update(container);
+
+  expect(navigation.current?.getCurrentRoute()).toEqual({
+    key: 'bar-a',
+    name: 'bar-a',
+  });
+});

packages/core/src/types.tsx

@@ -422,6 +422,10 @@ export type NavigationContainerRef = NavigationHelpers<ParamListBase> &
      * Get the rehydrated navigation state of the navigation tree.
      */
     getRootState(): NavigationState;
+    /**
+     * Get the currently focused navigation route.
+     */
+    getCurrentRoute(): Route<string> | undefined;
   };
 
 export type TypedNavigator<