[go_router] Reduces excessive rebuilds due to inherited look up. (#4227)

fixes flutter/flutter#123570

packages/go_router/CHANGELOG.md

@@ -1,3 +1,12 @@
+## 9.0.0
+
+- **BREAKING CHANGE**:
+  - Removes GoRouter.location and GoRouter.canPop. Use GoRouterState.of().location and
+    Navigator.of().canPop instead.
+  - GoRouter does not `extends` ChangeNotifier.
+  - [Migration guide](https://flutter.dev/go/go-router-v9-breaking-changes)
+- Reduces excessive rebuilds due to inherited look up.
+
 ## 8.2.0
 
 - Adds onException to GoRouter constructor.

packages/go_router/README.md

@@ -37,6 +37,7 @@ See the API documentation for details on the following topics:
 - [Error handling](https://pub.dev/documentation/go_router/latest/topics/Error%20handling-topic.html)
 
 ## Migration guides
+- [Migrating to 9.0.0](https://flutter.dev/go/go-router-v9-breaking-changes).
 - [Migrating to 8.0.0](https://flutter.dev/go/go-router-v8-breaking-changes).
 - [Migrating to 7.0.0](https://flutter.dev/go/go-router-v7-breaking-changes).
 - [Migrating to 6.0.0](https://flutter.dev/go/go-router-v6-breaking-changes)

packages/go_router/lib/src/information_provider.dart

@@ -133,6 +133,14 @@ class GoRouteInformationProvider extends RouteInformationProvider
   RouteInformation get value => _value;
   RouteInformation _value;
 
+  @override
+  // TODO(chunhtai): remove this ignore once package minimum dart version is
+  // above 3.
+  // ignore: unnecessary_overrides
+  void notifyListeners() {
+    super.notifyListeners();
+  }
+
   void _setValue(String location, Object state) {
     final bool shouldNotify =
         _value.location != location || _value.state != state;

packages/go_router/lib/src/misc/inherited_router.dart

@@ -11,13 +11,13 @@ import '../router.dart';
 ///
 /// Used for to find the current GoRouter in the widget tree. This is useful
 /// when routing from anywhere in your app.
-class InheritedGoRouter extends InheritedNotifier<GoRouter> {
+class InheritedGoRouter extends InheritedWidget {
   /// Default constructor for the inherited go router.
   const InheritedGoRouter({
     required super.child,
     required this.goRouter,
     super.key,
-  }) : super(notifier: goRouter);
+  });
 
   /// The [GoRouter] that is made available to the widget tree.
   final GoRouter goRouter;
@@ -27,4 +27,7 @@ class InheritedGoRouter extends InheritedNotifier<GoRouter> {
     super.debugFillProperties(properties);
     properties.add(DiagnosticsProperty<GoRouter>('goRouter', goRouter));
   }
+
+  @override
+  bool updateShouldNotify(covariant InheritedWidget oldWidget) => false;
 }

packages/go_router/lib/src/router.dart

@@ -62,7 +62,7 @@ typedef GoExceptionHandler = void Function(
 /// {@category Deep linking}
 /// {@category Error handling}
 /// {@category Named routes}
-class GoRouter extends ChangeNotifier implements RouterConfig<RouteMatchList> {
+class GoRouter implements RouterConfig<RouteMatchList> {
   /// Default constructor to configure a GoRouter with a routes builder
   /// and an error page builder.
   ///
@@ -152,7 +152,6 @@ class GoRouter extends ChangeNotifier implements RouterConfig<RouteMatchList> {
       builderWithNav: (BuildContext context, Widget child) =>
           InheritedGoRouter(goRouter: this, child: child),
     );
-    routerDelegate.addListener(_handleStateMayChange);
 
     assert(() {
       log.info('setting initial location $initialLocation');
@@ -296,34 +295,9 @@ class GoRouter extends ChangeNotifier implements RouterConfig<RouteMatchList> {
   @override
   late final GoRouteInformationParser routeInformationParser;
 
-  /// Gets the current location.
-  // TODO(chunhtai): deprecates this once go_router_builder is migrated to
-  // GoRouterState.of.
-  String get location => _location;
-  String _location = '/';
-
   /// Returns `true` if there is at least two or more route can be pop.
   bool canPop() => routerDelegate.canPop();
 
-  void _handleStateMayChange() {
-    final String newLocation;
-    if (routerDelegate.currentConfiguration.isNotEmpty &&
-        routerDelegate.currentConfiguration.matches.last
-            is ImperativeRouteMatch) {
-      newLocation = (routerDelegate.currentConfiguration.matches.last
-              as ImperativeRouteMatch)
-          .matches
-          .uri
-          .toString();
-    } else {
-      newLocation = routerDelegate.currentConfiguration.uri.toString();
-    }
-    if (_location != newLocation) {
-      _location = newLocation;
-      notifyListeners();
-    }
-  }
-
   /// Get a location from route name and parameters.
   /// This is useful for redirecting to a named location.
   String namedLocation(
@@ -488,7 +462,7 @@ class GoRouter extends ChangeNotifier implements RouterConfig<RouteMatchList> {
   /// of any GoRoute under it.
   void pop<T extends Object?>([T? result]) {
     assert(() {
-      log.info('popping $location');
+      log.info('popping ${routerDelegate.currentConfiguration.uri}');
       return true;
     }());
     routerDelegate.pop<T>(result);
@@ -497,7 +471,7 @@ class GoRouter extends ChangeNotifier implements RouterConfig<RouteMatchList> {
   /// Refresh the route.
   void refresh() {
     assert(() {
-      log.info('refreshing $location');
+      log.info('refreshing ${routerDelegate.currentConfiguration.uri}');
       return true;
     }());
     routeInformationProvider.notifyListeners();
@@ -507,27 +481,25 @@ class GoRouter extends ChangeNotifier implements RouterConfig<RouteMatchList> {
   ///
   /// This method throws when it is called during redirects.
   static GoRouter of(BuildContext context) {
-    final InheritedGoRouter? inherited =
-        context.dependOnInheritedWidgetOfExactType<InheritedGoRouter>();
+    final GoRouter? inherited = maybeOf(context);
     assert(inherited != null, 'No GoRouter found in context');
-    return inherited!.goRouter;
+    return inherited!;
   }
 
   /// The current GoRouter in the widget tree, if any.
   ///
   /// This method returns null when it is called during redirects.
   static GoRouter? maybeOf(BuildContext context) {
-    final InheritedGoRouter? inherited =
-        context.dependOnInheritedWidgetOfExactType<InheritedGoRouter>();
+    final InheritedGoRouter? inherited = context
+        .getElementForInheritedWidgetOfExactType<InheritedGoRouter>()
+        ?.widget as InheritedGoRouter?;
     return inherited?.goRouter;
   }
 
-  @override
+  /// Disposes resource created by this object.
   void dispose() {
     routeInformationProvider.dispose();
-    routerDelegate.removeListener(_handleStateMayChange);
     routerDelegate.dispose();
-    super.dispose();
   }
 
   String _effectiveInitialLocation(String? initialLocation) {

packages/go_router/pubspec.yaml

@@ -1,7 +1,7 @@
 name: go_router
 description: A declarative router for Flutter based on Navigation 2 supporting
   deep linking, data-driven routes and more
-version: 8.2.0
+version: 9.0.0
 repository: https://github.com/flutter/packages/tree/main/packages/go_router
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+go_router%22
 

packages/go_router/test/extension_test.dart

@@ -5,6 +5,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:go_router/go_router.dart';
+import 'package:go_router/src/match.dart';
 
 void main() {
   group('replaceNamed', () {
@@ -37,7 +38,10 @@ void main() {
       final GoRouter router = await createGoRouter(tester);
       await tester.tap(find.text('Settings'));
       await tester.pumpAndSettle();
-      expect(router.location, '/page-0/settings?search=notification');
+      final ImperativeRouteMatch routeMatch = router
+          .routerDelegate.currentConfiguration.last as ImperativeRouteMatch;
+      expect(routeMatch.matches.uri.toString(),
+          '/page-0/settings?search=notification');
     });
   });
 }