Cleanup to navigation_and_routing sample (#881)

- make more things private and final, where possible
- remove unused members
- used expression bodies, where possible

navigation_and_routing/lib/src/app.dart

@@ -18,12 +18,11 @@ class Bookstore extends StatefulWidget {
 }
 
 class _BookstoreState extends State<Bookstore> {
-  final auth = BookstoreAuth();
-  late final BookstoreRouteGuard guard;
-  late final RouteState routeState;
-  late final SimpleRouterDelegate routerDelegate;
-  late final TemplateRouteParser routeParser;
-  final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
+  final _auth = BookstoreAuth();
+  final _navigatorKey = GlobalKey<NavigatorState>();
+  late final RouteState _routeState;
+  late final SimpleRouterDelegate _routerDelegate;
+  late final TemplateRouteParser _routeParser;
 
   final library = Library()
     ..addBook(
@@ -49,10 +48,10 @@ class _BookstoreState extends State<Bookstore> {
 
   @override
   void initState() {
-    guard = BookstoreRouteGuard(auth: auth);
+    final guard = BookstoreRouteGuard(auth: _auth);
 
     /// Configure the parser with all of the app's allowed path templates.
-    routeParser = TemplateRouteParser(
+    _routeParser = TemplateRouteParser(
       allowedPaths: [
         '/signin',
         '/authors',
@@ -67,50 +66,48 @@ class _BookstoreState extends State<Bookstore> {
       initialRoute: '/signin',
     );
 
-    routeState = RouteState(routeParser);
+    _routeState = RouteState(_routeParser);
 
-    routerDelegate = SimpleRouterDelegate(
-      routeState: routeState,
-      navigatorKey: navigatorKey,
+    _routerDelegate = SimpleRouterDelegate(
+      routeState: _routeState,
+      navigatorKey: _navigatorKey,
       builder: (context) => BookstoreNavigator(
-        navigatorKey: navigatorKey,
+        navigatorKey: _navigatorKey,
       ),
     );
 
     // Listen for when the user logs out and display the signin screen.
-    auth.addListener(_handleAuthStateChanged);
+    _auth.addListener(_handleAuthStateChanged);
 
     super.initState();
   }
 
   @override
-  Widget build(BuildContext context) {
-    return RouteStateScope(
-      notifier: routeState,
+  Widget build(BuildContext context) => RouteStateScope(
+        notifier: _routeState,
         child: BookstoreAuthScope(
-        notifier: auth,
+          notifier: _auth,
           child: LibraryScope(
             library: library,
             child: MaterialApp.router(
-            routerDelegate: routerDelegate,
-            routeInformationParser: routeParser,
+              routerDelegate: _routerDelegate,
+              routeInformationParser: _routeParser,
             ),
           ),
         ),
       );
-  }
 
   void _handleAuthStateChanged() {
-    if (!auth.signedIn) {
-      routeState.go('/signin');
+    if (!_auth.signedIn) {
+      _routeState.go('/signin');
     }
   }
 
   @override
   void dispose() {
-    auth.removeListener(_handleAuthStateChanged);
-    routeState.dispose();
-    routerDelegate.dispose();
+    _auth.removeListener(_handleAuthStateChanged);
+    _routeState.dispose();
+    _routerDelegate.dispose();
     super.dispose();
   }
 }

navigation_and_routing/lib/src/auth/auth.dart

@@ -9,9 +9,7 @@ import 'package:flutter/widgets.dart';
 class BookstoreAuth extends ChangeNotifier {
   bool _signedIn = false;
 
-  bool get signedIn {
-    return _signedIn;
-  }
+  bool get signedIn => _signedIn;
 
   Future<void> signOut() async {
     await Future<void>.delayed(const Duration(milliseconds: 200));
@@ -30,9 +28,8 @@ class BookstoreAuth extends ChangeNotifier {
   }
 
   @override
-  bool operator ==(Object other) {
-    return other is BookstoreAuth && other._signedIn == _signedIn;
-  }
+  bool operator ==(Object other) =>
+      other is BookstoreAuth && other._signedIn == _signedIn;
 
   @override
   int get hashCode => _signedIn.hashCode;
@@ -45,9 +42,7 @@ class BookstoreAuthScope extends InheritedNotifier<BookstoreAuth> {
     Key? key,
   }) : super(key: key, notifier: notifier, child: child);
 
-  static BookstoreAuth? of(BuildContext context) {
-    return context
+  static BookstoreAuth? of(BuildContext context) => context
       .dependOnInheritedWidgetOfExactType<BookstoreAuthScope>()
       ?.notifier;
 }
-}

navigation_and_routing/lib/src/auth/auth_guard.dart

@@ -7,7 +7,7 @@ import 'auth.dart';
 
 /// An implementation of [RouteGuard] that redirects to /signIn
 class BookstoreRouteGuard implements RouteGuard<ParsedRoute> {
-  BookstoreAuth auth;
+  final BookstoreAuth auth;
 
   BookstoreRouteGuard({
     required this.auth,

navigation_and_routing/lib/src/data/library.dart

@@ -32,15 +32,11 @@ class Library {
     allBooks.add(book);
   }
 
-  List<Book> get popularBooks {
-    return [
+  List<Book> get popularBooks => [
         ...allBooks.where((book) => book.isPopular),
       ];
-  }
 
-  List<Book> get newBooks {
-    return [
+  List<Book> get newBooks => [
         ...allBooks.where((book) => book.isNew),
       ];
 }
-}

navigation_and_routing/lib/src/routing/delegate.dart

@@ -28,9 +28,7 @@ class SimpleRouterDelegate extends RouterDelegate<ParsedRoute>
   }
 
   @override
-  Widget build(BuildContext context) {
-    return builder(context);
-  }
+  Widget build(BuildContext context) => builder(context);
 
   @override
   Future<void> setNewRoutePath(ParsedRoute configuration) async {
@@ -39,9 +37,7 @@ class SimpleRouterDelegate extends RouterDelegate<ParsedRoute>
   }
 
   @override
-  ParsedRoute get currentConfiguration {
-    return routeState.route;
-  }
+  ParsedRoute get currentConfiguration => routeState.route;
 
   @override
   void dispose() {

navigation_and_routing/lib/src/routing/parsed_route.dart

@@ -27,13 +27,12 @@ class ParsedRoute {
       this.path, this.pathTemplate, this.parameters, this.queryParameters);
 
   @override
-  bool operator ==(Object other) {
-    return other is ParsedRoute &&
+  bool operator ==(Object other) =>
+      other is ParsedRoute &&
       other.pathTemplate == pathTemplate &&
       other.path == path &&
       _mapEquality.equals(parameters, other.parameters) &&
       _mapEquality.equals(queryParameters, other.queryParameters);
-  }
 
   @override
   int get hashCode => hash4(

navigation_and_routing/lib/src/routing/parser.dart

@@ -44,9 +44,8 @@ class TemplateRouteParser extends RouteInformationParser<ParsedRoute> {
 
   @override
   Future<ParsedRoute> parseRouteInformation(
-      RouteInformation routeInformation) async {
-    return await _parse(routeInformation);
-  }
+          RouteInformation routeInformation) async =>
+      await _parse(routeInformation);
 
   Future<ParsedRoute> _parse(RouteInformation routeInformation) async {
     final path = routeInformation.location!;
@@ -74,7 +73,6 @@ class TemplateRouteParser extends RouteInformationParser<ParsedRoute> {
   }
 
   @override
-  RouteInformation restoreRouteInformation(ParsedRoute configuration) {
-    return RouteInformation(location: configuration.path);
-  }
+  RouteInformation restoreRouteInformation(ParsedRoute configuration) =>
+      RouteInformation(location: configuration.path);
 }

navigation_and_routing/lib/src/routing/route_state.dart

@@ -44,9 +44,6 @@ class RouteStateScope extends InheritedNotifier<RouteState> {
     Key? key,
   }) : super(key: key, notifier: notifier, child: child);
 
-  static RouteState? of(BuildContext context) {
-    return context
-        .dependOnInheritedWidgetOfExactType<RouteStateScope>()
-        ?.notifier;
-  }
+  static RouteState? of(BuildContext context) =>
+      context.dependOnInheritedWidgetOfExactType<RouteStateScope>()?.notifier;
 }

navigation_and_routing/lib/src/screens/author_details.dart

@@ -17,8 +17,7 @@ class AuthorDetailsScreen extends StatelessWidget {
   }) : super(key: key);
 
   @override
-  Widget build(BuildContext context) {
-    return Scaffold(
+  Widget build(BuildContext context) => Scaffold(
         appBar: AppBar(
           title: Text(author.name),
         ),
@@ -38,4 +37,3 @@ class AuthorDetailsScreen extends StatelessWidget {
         ),
       );
 }
-}

navigation_and_routing/lib/src/screens/authors.dart

@@ -14,8 +14,7 @@ class AuthorsScreen extends StatelessWidget {
   const AuthorsScreen({Key? key}) : super(key: key);
 
   @override
-  Widget build(BuildContext context) {
-    return Scaffold(
+  Widget build(BuildContext context) => Scaffold(
         appBar: AppBar(
           title: Text(title),
         ),
@@ -27,4 +26,3 @@ class AuthorsScreen extends StatelessWidget {
         ),
       );
 }
-}

navigation_and_routing/lib/src/screens/book_details.dart

@@ -45,21 +45,18 @@ class BookDetailsScreen extends StatelessWidget {
               onPressed: () {
                 Navigator.of(context).push<void>(
                   MaterialPageRoute<void>(
-                    builder: (context) {
-                      return AuthorDetailsScreen(author: book!.author);
-                    },
+                    builder: (context) =>
+                        AuthorDetailsScreen(author: book!.author),
                   ),
                 );
               },
             ),
             Link(
               uri: Uri.parse('/author/${book!.author.id}'),
-              builder: (context, followLink) {
-                return TextButton(
+              builder: (context, followLink) => TextButton(
                 onPressed: followLink,
                 child: const Text('View author (Link)'),
-                );
-              },
+              ),
             ),
           ],
         ),

navigation_and_routing/lib/src/screens/books.dart

@@ -10,11 +10,8 @@ import '../widgets/book_list.dart';
 import '../widgets/library_scope.dart';
 
 class BooksScreen extends StatefulWidget {
-  final ParsedRoute currentRoute;
-
   const BooksScreen({
     Key? key,
-    required this.currentRoute,
   }) : super(key: key);
 
   @override
@@ -36,7 +33,7 @@ class _BooksScreenState extends State<BooksScreen>
   void didChangeDependencies() {
     super.didChangeDependencies();
 
-    final newPath = routeState.route.pathTemplate;
+    final newPath = _routeState.route.pathTemplate;
     if (newPath.startsWith('/books/popular')) {
       _tabController.index = 0;
     } else if (newPath.startsWith('/books/new')) {
@@ -96,35 +93,23 @@ class _BooksScreenState extends State<BooksScreen>
     );
   }
 
-  String get title {
-    switch (_tabController.index) {
-      case 1:
-        return 'New';
-      case 2:
-        return 'All';
-      case 0:
-      default:
-        return 'Popular';
-    }
-  }
-
-  RouteState get routeState => RouteStateScope.of(context)!;
+  RouteState get _routeState => RouteStateScope.of(context)!;
 
   void _handleBookTapped(Book book) {
-    routeState.go('/book/${book.id}');
+    _routeState.go('/book/${book.id}');
   }
 
   void _handleTabIndexChanged() {
     switch (_tabController.index) {
       case 1:
-        routeState.go('/books/new');
+        _routeState.go('/books/new');
         break;
       case 2:
-        routeState.go('/books/all');
+        _routeState.go('/books/all');
         break;
       case 0:
       default:
-        routeState.go('/books/popular');
+        _routeState.go('/books/popular');
         break;
     }
   }

navigation_and_routing/lib/src/screens/navigator.dart

@@ -30,10 +30,10 @@ class BookstoreNavigator extends StatefulWidget {
 }
 
 class _BookstoreNavigatorState extends State<BookstoreNavigator> {
-  final signInKey = const ValueKey('Sign in');
-  final scaffoldKey = const ValueKey<String>('App scaffold');
-  final bookDetailsKey = const ValueKey<String>('Book details screen');
-  final authorDetailsKey = const ValueKey<String>('Author details screen');
+  final _signInKey = const ValueKey('Sign in');
+  final _scaffoldKey = const ValueKey<String>('App scaffold');
+  final _bookDetailsKey = const ValueKey<String>('Book details screen');
+  final _authorDetailsKey = const ValueKey<String>('Author details screen');
 
   @override
   Widget build(BuildContext context) {
@@ -60,12 +60,12 @@ class _BookstoreNavigatorState extends State<BookstoreNavigator> {
         // When a page that is stacked on top of the scaffold is popped, display
         // the /books or /authors tab in BookstoreScaffold.
         if (route.settings is Page &&
-            (route.settings as Page).key == bookDetailsKey) {
+            (route.settings as Page).key == _bookDetailsKey) {
           routeState.go('/books/popular');
         }
 
         if (route.settings is Page &&
-            (route.settings as Page).key == authorDetailsKey) {
+            (route.settings as Page).key == _authorDetailsKey) {
           routeState.go('/authors');
         }
 
@@ -75,7 +75,7 @@ class _BookstoreNavigatorState extends State<BookstoreNavigator> {
         if (routeState.route.pathTemplate == '/signin')
           // Display the sign in screen.
           FadeTransitionPage<void>(
-            key: signInKey,
+            key: _signInKey,
             child: SignInScreen(
               onSignIn: (credentials) async {
                 var signedIn = await authState.signIn(
@@ -89,21 +89,21 @@ class _BookstoreNavigatorState extends State<BookstoreNavigator> {
         else ...[
           // Display the app
           FadeTransitionPage<void>(
-            key: scaffoldKey,
+            key: _scaffoldKey,
             child: const BookstoreScaffold(),
           ),
           // Add an additional page to the stack if the user is viewing a book
           // or an author
           if (selectedBook != null)
             MaterialPage<void>(
-              key: bookDetailsKey,
+              key: _bookDetailsKey,
               child: BookDetailsScreen(
                 book: selectedBook,
               ),
             )
           else if (selectedAuthor != null)
             MaterialPage<void>(
-              key: authorDetailsKey,
+              key: _authorDetailsKey,
               child: AuthorDetailsScreen(
                 author: selectedAuthor,
               ),

navigation_and_routing/lib/src/screens/scaffold_body.dart

@@ -41,9 +41,9 @@ class BookstoreScaffoldBody extends StatelessWidget {
           )
         else if (currentRoute.pathTemplate.startsWith('/books') ||
             currentRoute.pathTemplate == '/')
-          FadeTransitionPage<void>(
-            key: const ValueKey('books'),
-            child: BooksScreen(currentRoute: currentRoute),
+          const FadeTransitionPage<void>(
+            key: ValueKey('books'),
+            child: BooksScreen(),
           )
 
         // Avoid building a Navigator with an empty `pages` list when the

navigation_and_routing/lib/src/screens/settings.dart

@@ -17,8 +17,7 @@ class SettingsScreen extends StatefulWidget {
 
 class _SettingsScreenState extends State<SettingsScreen> {
   @override
-  Widget build(BuildContext context) {
-    return Scaffold(
+  Widget build(BuildContext context) => Scaffold(
         body: SafeArea(
           child: SingleChildScrollView(
             child: Align(
@@ -37,7 +36,6 @@ class _SettingsScreenState extends State<SettingsScreen> {
         ),
       );
 }
-}
 
 class SettingsContent extends StatelessWidget {
   const SettingsContent({
@@ -45,8 +43,7 @@ class SettingsContent extends StatelessWidget {
   }) : super(key: key);
 
   @override
-  Widget build(BuildContext context) {
-    return Column(
+  Widget build(BuildContext context) => Column(
         children: [
           ...[
             Text(
@@ -61,12 +58,10 @@ class SettingsContent extends StatelessWidget {
             ),
             Link(
               uri: Uri.parse('/book/0'),
-            builder: (context, followLink) {
-              return TextButton(
+              builder: (context, followLink) => TextButton(
                 onPressed: followLink,
                 child: const Text('Go directly to /book/0 (Link)'),
-              );
-            },
+              ),
             ),
             TextButton(
               child: const Text('Go directly to /book/0 (RouteState)'),
@@ -98,4 +93,3 @@ class SettingsContent extends StatelessWidget {
         ],
       );
 }
-}

navigation_and_routing/lib/src/screens/sign_in.dart

@@ -29,8 +29,7 @@ class _SignInScreenState extends State<SignInScreen> {
   final _passwordController = TextEditingController();
 
   @override
-  Widget build(BuildContext context) {
-    return Scaffold(
+  Widget build(BuildContext context) => Scaffold(
         body: Center(
           child: Card(
             child: Container(
@@ -68,4 +67,3 @@ class _SignInScreenState extends State<SignInScreen> {
         ),
       );
 }
-}

navigation_and_routing/lib/src/widgets/author_list.dart

@@ -17,11 +17,9 @@ class AuthorList extends StatelessWidget {
   }) : super(key: key);
 
   @override
-  Widget build(BuildContext context) {
-    return ListView.builder(
+  Widget build(BuildContext context) => ListView.builder(
         itemCount: authors.length,
-      itemBuilder: (context, index) {
-        return ListTile(
+        itemBuilder: (context, index) => ListTile(
           title: Text(
             authors[index].name,
           ),
@@ -29,8 +27,6 @@ class AuthorList extends StatelessWidget {
             '${authors[index].books.length} books',
           ),
           onTap: onTap != null ? () => onTap!(authors[index]) : null,
+        ),
       );
-      },
-    );
-  }
 }

navigation_and_routing/lib/src/widgets/book_list.dart

@@ -17,11 +17,9 @@ class BookList extends StatelessWidget {
   }) : super(key: key);
 
   @override
-  Widget build(BuildContext context) {
-    return ListView.builder(
+  Widget build(BuildContext context) => ListView.builder(
         itemCount: books.length,
-      itemBuilder: (context, index) {
-        return ListTile(
+        itemBuilder: (context, index) => ListTile(
           title: Text(
             books[index].title,
           ),
@@ -29,8 +27,6 @@ class BookList extends StatelessWidget {
             books[index].author.name,
           ),
           onTap: onTap != null ? () => onTap!(books[index]) : null,
+        ),
       );
-      },
-    );
-  }
 }

navigation_and_routing/lib/src/widgets/fade_transition_page.dart

@@ -15,15 +15,14 @@ class FadeTransitionPage<T> extends Page<T> {
   }) : super(key: key);
 
   @override
-  Route<T> createRoute(BuildContext context) {
-    return PageBasedFadeTransitionRoute<T>(this);
-  }
+  Route<T> createRoute(BuildContext context) =>
+      PageBasedFadeTransitionRoute<T>(this);
 }
 
 class PageBasedFadeTransitionRoute<T> extends PageRoute<T> {
-  final FadeTransitionPage<T> page;
+  final FadeTransitionPage<T> _page;
 
-  PageBasedFadeTransitionRoute(this.page) : super(settings: page);
+  PageBasedFadeTransitionRoute(this._page) : super(settings: _page);
 
   @override
   Color? get barrierColor => null;
@@ -32,7 +31,7 @@ class PageBasedFadeTransitionRoute<T> extends PageRoute<T> {
   String? get barrierLabel => null;
 
   @override
-  Duration get transitionDuration => page.duration;
+  Duration get transitionDuration => _page.duration;
 
   @override
   bool get maintainState => true;
@@ -49,7 +48,6 @@ class PageBasedFadeTransitionRoute<T> extends PageRoute<T> {
 
   @override
   Widget buildTransitions(BuildContext context, Animation<double> animation,
-      Animation<double> secondaryAnimation, Widget child) {
-    return child;
-  }
+          Animation<double> secondaryAnimation, Widget child) =>
+      child;
 }

navigation_and_routing/lib/src/widgets/library_scope.dart

@@ -19,7 +19,6 @@ class LibraryScope extends InheritedWidget {
   bool updateShouldNotify(LibraryScope oldWidget) =>
       library != oldWidget.library;
 
-  static Library of(BuildContext context) {
-    return context.dependOnInheritedWidgetOfExactType<LibraryScope>()!.library;
-  }
+  static Library of(BuildContext context) =>
+      context.dependOnInheritedWidgetOfExactType<LibraryScope>()!.library;
 }