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lib/13/go/async_redirection.dart

@@ -0,0 +1,244 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+// This scenario demonstrates how to use redirect to handle a asynchronous
+// sign-in flow.
+//
+// The `StreamAuth` is a mock of google_sign_in. This example wraps it with an
+// InheritedNotifier, StreamAuthScope, and relies on
+// `dependOnInheritedWidgetOfExactType` to create a dependency between the
+// notifier and go_router's parsing pipeline. When StreamAuth broadcasts new
+// event, the dependency will cause the go_router to reparse the current url
+// which will also trigger the redirect.
+
+void main() => runApp(StreamAuthScope(child: App()));
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Redirection';
+
+  // add the login info into the tree as app state that can change over time
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+        debugShowCheckedModeBanner: false,
+      );
+
+  late final GoRouter _router = GoRouter(
+    routes: <GoRoute>[
+      GoRoute(
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const HomeScreen(),
+      ),
+      GoRoute(
+        path: '/login',
+        builder: (BuildContext context, GoRouterState state) =>
+            const LoginScreen(),
+      ),
+    ],
+
+    // redirect to the login page if the user is not logged in
+    redirect: (BuildContext context, GoRouterState state) async {
+      // Using `of` method creates a dependency of StreamAuthScope. It will
+      // cause go_router to reparse current route if StreamAuth has new sign-in
+      // information.
+      final bool loggedIn = await StreamAuthScope.of(context).isSignedIn();
+      final bool loggingIn = state.matchedLocation == '/login';
+      if (!loggedIn) {
+        return '/login';
+      }
+
+      // if the user is logged in but still on the login page, send them to
+      // the home page
+      if (loggingIn) {
+        return '/';
+      }
+
+      // no need to redirect at all
+      return null;
+    },
+  );
+}
+
+/// The login screen.
+class LoginScreen extends StatefulWidget {
+  /// Creates a [LoginScreen].
+  const LoginScreen({super.key});
+
+  @override
+  State<LoginScreen> createState() => _LoginScreenState();
+}
+
+class _LoginScreenState extends State<LoginScreen>
+    with TickerProviderStateMixin {
+  bool loggingIn = false;
+  late final AnimationController controller;
+
+  @override
+  void initState() {
+    super.initState();
+    controller = AnimationController(
+      vsync: this,
+      duration: const Duration(seconds: 1),
+    )..addListener(() {
+        setState(() {});
+      });
+    controller.repeat();
+  }
+
+  @override
+  void dispose() {
+    controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              if (loggingIn) CircularProgressIndicator(value: controller.value),
+              if (!loggingIn)
+                ElevatedButton(
+                  onPressed: () {
+                    StreamAuthScope.of(context).signIn('test-user');
+                    setState(() {
+                      loggingIn = true;
+                    });
+                  },
+                  child: const Text('Login'),
+                ),
+            ],
+          ),
+        ),
+      );
+}
+
+/// The home screen.
+class HomeScreen extends StatelessWidget {
+  /// Creates a [HomeScreen].
+  const HomeScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final StreamAuth info = StreamAuthScope.of(context);
+
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text(App.title),
+        actions: <Widget>[
+          IconButton(
+            onPressed: () => info.signOut(),
+            tooltip: 'Logout: ${info.currentUser}',
+            icon: const Icon(Icons.logout),
+          )
+        ],
+      ),
+      body: const Center(
+        child: Text('HomeScreen'),
+      ),
+    );
+  }
+}
+
+/// A scope that provides [StreamAuth] for the subtree.
+class StreamAuthScope extends InheritedNotifier<StreamAuthNotifier> {
+  /// Creates a [StreamAuthScope] sign in scope.
+  StreamAuthScope({
+    super.key,
+    required super.child,
+  }) : super(
+          notifier: StreamAuthNotifier(),
+        );
+
+  /// Gets the [StreamAuth].
+  static StreamAuth of(BuildContext context) {
+    return context
+        .dependOnInheritedWidgetOfExactType<StreamAuthScope>()!
+        .notifier!
+        .streamAuth;
+  }
+}
+
+/// A class that converts [StreamAuth] into a [ChangeNotifier].
+class StreamAuthNotifier extends ChangeNotifier {
+  /// Creates a [StreamAuthNotifier].
+  StreamAuthNotifier() : streamAuth = StreamAuth() {
+    streamAuth.onCurrentUserChanged.listen((String? string) {
+      notifyListeners();
+    });
+  }
+
+  /// The stream auth client.
+  final StreamAuth streamAuth;
+}
+
+/// An asynchronous log in services mock with stream similar to google_sign_in.
+///
+/// This class adds an artificial delay of 3 second when logging in an user, and
+/// will automatically clear the login session after [refreshInterval].
+class StreamAuth {
+  /// Creates an [StreamAuth] that clear the current user session in
+  /// [refeshInterval] second.
+  StreamAuth({this.refreshInterval = 20})
+      : _userStreamController = StreamController<String?>.broadcast() {
+    _userStreamController.stream.listen((String? currentUser) {
+      _currentUser = currentUser;
+    });
+  }
+
+  /// The current user.
+  String? get currentUser => _currentUser;
+  String? _currentUser;
+
+  /// Checks whether current user is signed in with an artificial delay to mimic
+  /// async operation.
+  Future<bool> isSignedIn() async {
+    await Future<void>.delayed(const Duration(seconds: 1));
+    return _currentUser != null;
+  }
+
+  /// A stream that notifies when current user has changed.
+  Stream<String?> get onCurrentUserChanged => _userStreamController.stream;
+  final StreamController<String?> _userStreamController;
+
+  /// The interval that automatically signs out the user.
+  final int refreshInterval;
+
+  Timer? _timer;
+  Timer _createRefreshTimer() {
+    return Timer(Duration(seconds: refreshInterval), () {
+      _userStreamController.add(null);
+      _timer = null;
+    });
+  }
+
+  /// Signs in a user with an artificial delay to mimic async operation.
+  Future<void> signIn(String newUserName) async {
+    await Future<void>.delayed(const Duration(seconds: 3));
+    _userStreamController.add(newUserName);
+    _timer?.cancel();
+    _timer = _createRefreshTimer();
+  }
+
+  /// Signs out the current user.
+  Future<void> signOut() async {
+    _timer?.cancel();
+    _timer = null;
+    _userStreamController.add(null);
+  }
+}

lib/13/go/books/main.dart

@@ -0,0 +1,171 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:collection/collection.dart';
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+import 'src/auth.dart';
+import 'src/data/author.dart';
+import 'src/data/book.dart';
+import 'src/data/library.dart';
+import 'src/screens/author_details.dart';
+import 'src/screens/authors.dart';
+import 'src/screens/book_details.dart';
+import 'src/screens/books.dart';
+import 'src/screens/scaffold.dart';
+import 'src/screens/settings.dart';
+import 'src/screens/sign_in.dart';
+
+void main() => runApp(Bookstore());
+
+/// The book store view.
+class Bookstore extends StatelessWidget {
+  /// Creates a [Bookstore].
+  Bookstore({super.key});
+
+  final ValueKey<String> _scaffoldKey = const ValueKey<String>('App scaffold');
+
+  @override
+  Widget build(BuildContext context) => BookstoreAuthScope(
+        notifier: _auth,
+        child: MaterialApp.router(
+          routerConfig: _router,
+        ),
+      );
+
+  final BookstoreAuth _auth = BookstoreAuth();
+
+  late final GoRouter _router = GoRouter(
+    routes: <GoRoute>[
+      GoRoute(
+        path: '/',
+        redirect: (_, __) => '/books',
+      ),
+      GoRoute(
+        path: '/signin',
+        pageBuilder: (BuildContext context, GoRouterState state) =>
+            FadeTransitionPage(
+          key: state.pageKey,
+          child: SignInScreen(
+            onSignIn: (Credentials credentials) {
+              BookstoreAuthScope.of(context)
+                  .signIn(credentials.username, credentials.password);
+            },
+          ),
+        ),
+      ),
+      GoRoute(
+        path: '/books',
+        redirect: (_, __) => '/books/popular',
+      ),
+      GoRoute(
+        path: '/book/:bookId',
+        redirect: (BuildContext context, GoRouterState state) =>
+            '/books/all/${state.pathParameters['bookId']}',
+      ),
+      GoRoute(
+        path: '/books/:kind(new|all|popular)',
+        pageBuilder: (BuildContext context, GoRouterState state) =>
+            FadeTransitionPage(
+          key: _scaffoldKey,
+          child: BookstoreScaffold(
+            selectedTab: ScaffoldTab.books,
+            child: BooksScreen(state.pathParameters['kind']!),
+          ),
+        ),
+        routes: <GoRoute>[
+          GoRoute(
+            path: ':bookId',
+            builder: (BuildContext context, GoRouterState state) {
+              final String bookId = state.pathParameters['bookId']!;
+              final Book? selectedBook = libraryInstance.allBooks
+                  .firstWhereOrNull((Book b) => b.id.toString() == bookId);
+
+              return BookDetailsScreen(book: selectedBook);
+            },
+          ),
+        ],
+      ),
+      GoRoute(
+        path: '/author/:authorId',
+        redirect: (BuildContext context, GoRouterState state) =>
+            '/authors/${state.pathParameters['authorId']}',
+      ),
+      GoRoute(
+        path: '/authors',
+        pageBuilder: (BuildContext context, GoRouterState state) =>
+            FadeTransitionPage(
+          key: _scaffoldKey,
+          child: const BookstoreScaffold(
+            selectedTab: ScaffoldTab.authors,
+            child: AuthorsScreen(),
+          ),
+        ),
+        routes: <GoRoute>[
+          GoRoute(
+            path: ':authorId',
+            builder: (BuildContext context, GoRouterState state) {
+              final int authorId = int.parse(state.pathParameters['authorId']!);
+              final Author? selectedAuthor = libraryInstance.allAuthors
+                  .firstWhereOrNull((Author a) => a.id == authorId);
+
+              return AuthorDetailsScreen(author: selectedAuthor);
+            },
+          ),
+        ],
+      ),
+      GoRoute(
+        path: '/settings',
+        pageBuilder: (BuildContext context, GoRouterState state) =>
+            FadeTransitionPage(
+          key: _scaffoldKey,
+          child: const BookstoreScaffold(
+            selectedTab: ScaffoldTab.settings,
+            child: SettingsScreen(),
+          ),
+        ),
+      ),
+    ],
+    redirect: _guard,
+    refreshListenable: _auth,
+    debugLogDiagnostics: true,
+  );
+
+  String? _guard(BuildContext context, GoRouterState state) {
+    final bool signedIn = _auth.signedIn;
+    final bool signingIn = state.matchedLocation == '/signin';
+
+    // Go to /signin if the user is not signed in
+    if (!signedIn && !signingIn) {
+      return '/signin';
+    }
+    // Go to /books if the user is signed in and tries to go to /signin.
+    else if (signedIn && signingIn) {
+      return '/books';
+    }
+
+    // no redirect
+    return null;
+  }
+}
+
+/// A page that fades in an out.
+class FadeTransitionPage extends CustomTransitionPage<void> {
+  /// Creates a [FadeTransitionPage].
+  FadeTransitionPage({
+    required LocalKey super.key,
+    required super.child,
+  }) : super(
+            transitionsBuilder: (BuildContext context,
+                    Animation<double> animation,
+                    Animation<double> secondaryAnimation,
+                    Widget child) =>
+                FadeTransition(
+                  opacity: animation.drive(_curveTween),
+                  child: child,
+                ));
+
+  static final CurveTween _curveTween = CurveTween(curve: Curves.easeIn);
+}

lib/13/go/books/src/auth.dart

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+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/widgets.dart';
+
+/// A mock authentication service.
+class BookstoreAuth extends ChangeNotifier {
+  bool _signedIn = false;
+
+  /// Whether user has signed in.
+  bool get signedIn => _signedIn;
+
+  /// Signs out the current user.
+  Future<void> signOut() async {
+    await Future<void>.delayed(const Duration(milliseconds: 200));
+    // Sign out.
+    _signedIn = false;
+    notifyListeners();
+  }
+
+  /// Signs in a user.
+  Future<bool> signIn(String username, String password) async {
+    await Future<void>.delayed(const Duration(milliseconds: 200));
+
+    // Sign in. Allow any password.
+    _signedIn = true;
+    notifyListeners();
+    return _signedIn;
+  }
+}
+
+/// An inherited notifier to host [BookstoreAuth] for the subtree.
+class BookstoreAuthScope extends InheritedNotifier<BookstoreAuth> {
+  /// Creates a [BookstoreAuthScope].
+  const BookstoreAuthScope({
+    required BookstoreAuth super.notifier,
+    required super.child,
+    super.key,
+  });
+
+  /// Gets the [BookstoreAuth] above the context.
+  static BookstoreAuth of(BuildContext context) => context
+      .dependOnInheritedWidgetOfExactType<BookstoreAuthScope>()!
+      .notifier!;
+}

lib/13/go/books/src/data.dart

@@ -0,0 +1,7 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+export 'data/author.dart';
+export 'data/book.dart';
+export 'data/library.dart';

lib/13/go/books/src/data/author.dart

@@ -0,0 +1,23 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'book.dart';
+
+/// Author data class.
+class Author {
+  /// Creates an author data object.
+  Author({
+    required this.id,
+    required this.name,
+  });
+
+  /// The id of the author.
+  final int id;
+
+  /// The name of the author.
+  final String name;
+
+  /// The books of the author.
+  final List<Book> books = <Book>[];
+}

lib/13/go/books/src/data/book.dart

@@ -0,0 +1,32 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'author.dart';
+
+/// Book data class.
+class Book {
+  /// Creates a book data object.
+  Book({
+    required this.id,
+    required this.title,
+    required this.isPopular,
+    required this.isNew,
+    required this.author,
+  });
+
+  /// The id of the book.
+  final int id;
+
+  /// The title of the book.
+  final String title;
+
+  /// The author of the book.
+  final Author author;
+
+  /// Whether the book is popular.
+  final bool isPopular;
+
+  /// Whether the book is new.
+  final bool isNew;
+}

lib/13/go/books/src/data/library.dart

@@ -0,0 +1,76 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'author.dart';
+import 'book.dart';
+
+/// Library data mock.
+final Library libraryInstance = Library()
+  ..addBook(
+      title: 'Left Hand of Darkness',
+      authorName: 'Ursula K. Le Guin',
+      isPopular: true,
+      isNew: true)
+  ..addBook(
+      title: 'Too Like the Lightning',
+      authorName: 'Ada Palmer',
+      isPopular: false,
+      isNew: true)
+  ..addBook(
+      title: 'Kindred',
+      authorName: 'Octavia E. Butler',
+      isPopular: true,
+      isNew: false)
+  ..addBook(
+      title: 'The Lathe of Heaven',
+      authorName: 'Ursula K. Le Guin',
+      isPopular: false,
+      isNew: false);
+
+/// A library that contains books and authors.
+class Library {
+  /// The books in the library.
+  final List<Book> allBooks = <Book>[];
+
+  /// The authors in the library.
+  final List<Author> allAuthors = <Author>[];
+
+  /// Adds a book into the library.
+  void addBook({
+    required String title,
+    required String authorName,
+    required bool isPopular,
+    required bool isNew,
+  }) {
+    final Author author = allAuthors.firstWhere(
+      (Author author) => author.name == authorName,
+      orElse: () {
+        final Author value = Author(id: allAuthors.length, name: authorName);
+        allAuthors.add(value);
+        return value;
+      },
+    );
+
+    final Book book = Book(
+      id: allBooks.length,
+      title: title,
+      isPopular: isPopular,
+      isNew: isNew,
+      author: author,
+    );
+
+    author.books.add(book);
+    allBooks.add(book);
+  }
+
+  /// The list of popular books in the library.
+  List<Book> get popularBooks => <Book>[
+        ...allBooks.where((Book book) => book.isPopular),
+      ];
+
+  /// The list of new books in the library.
+  List<Book> get newBooks => <Book>[
+        ...allBooks.where((Book book) => book.isNew),
+      ];
+}

lib/13/go/books/src/screens/author_details.dart

@@ -0,0 +1,49 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+import '../data.dart';
+import '../widgets/book_list.dart';
+
+/// The author detail screen.
+class AuthorDetailsScreen extends StatelessWidget {
+  /// Creates an author detail screen.
+  const AuthorDetailsScreen({
+    required this.author,
+    super.key,
+  });
+
+  /// The author to be displayed.
+  final Author? author;
+
+  @override
+  Widget build(BuildContext context) {
+    if (author == null) {
+      return const Scaffold(
+        body: Center(
+          child: Text('No author found.'),
+        ),
+      );
+    }
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(author!.name),
+      ),
+      body: Center(
+        child: Column(
+          children: <Widget>[
+            Expanded(
+              child: BookList(
+                books: author!.books,
+                onTap: (Book book) => context.go('/book/${book.id}'),
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

lib/13/go/books/src/screens/authors.dart

@@ -0,0 +1,31 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+import '../data.dart';
+import '../widgets/author_list.dart';
+
+/// A screen that displays a list of authors.
+class AuthorsScreen extends StatelessWidget {
+  /// Creates an [AuthorsScreen].
+  const AuthorsScreen({super.key});
+
+  /// The title of the screen.
+  static const String title = 'Authors';
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(
+          title: const Text(title),
+        ),
+        body: AuthorList(
+          authors: libraryInstance.allAuthors,
+          onTap: (Author author) {
+            context.go('/author/${author.id}');
+          },
+        ),
+      );
+}

lib/13/go/books/src/screens/book_details.dart

@@ -0,0 +1,77 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:url_launcher/link.dart';
+
+import '../data.dart';
+import 'author_details.dart';
+
+/// A screen to display book details.
+class BookDetailsScreen extends StatelessWidget {
+  /// Creates a [BookDetailsScreen].
+  const BookDetailsScreen({
+    super.key,
+    this.book,
+  });
+
+  /// The book to be displayed.
+  final Book? book;
+
+  @override
+  Widget build(BuildContext context) {
+    if (book == null) {
+      return const Scaffold(
+        body: Center(
+          child: Text('No book found.'),
+        ),
+      );
+    }
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(book!.title),
+      ),
+      body: Center(
+        child: Column(
+          children: <Widget>[
+            Text(
+              book!.title,
+              style: Theme.of(context).textTheme.headlineMedium,
+            ),
+            Text(
+              book!.author.name,
+              style: Theme.of(context).textTheme.titleMedium,
+            ),
+            TextButton(
+              onPressed: () {
+                Navigator.of(context).push<void>(
+                  MaterialPageRoute<void>(
+                    builder: (BuildContext context) =>
+                        AuthorDetailsScreen(author: book!.author),
+                  ),
+                );
+              },
+              child: const Text('View author (navigator.push)'),
+            ),
+            Link(
+              uri: Uri.parse('/author/${book!.author.id}'),
+              builder: (BuildContext context, FollowLink? followLink) =>
+                  TextButton(
+                onPressed: followLink,
+                child: const Text('View author (Link)'),
+              ),
+            ),
+            TextButton(
+              onPressed: () {
+                context.push('/author/${book!.author.id}');
+              },
+              child: const Text('View author (GoRouter.push)'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

lib/13/go/books/src/screens/books.dart

@@ -0,0 +1,118 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+import '../data.dart';
+import '../widgets/book_list.dart';
+
+/// A screen that displays a list of books.
+class BooksScreen extends StatefulWidget {
+  /// Creates a [BooksScreen].
+  const BooksScreen(this.kind, {super.key});
+
+  /// Which tab to display.
+  final String kind;
+
+  @override
+  State<BooksScreen> createState() => _BooksScreenState();
+}
+
+class _BooksScreenState extends State<BooksScreen>
+    with SingleTickerProviderStateMixin {
+  late TabController _tabController;
+
+  @override
+  void initState() {
+    super.initState();
+    _tabController = TabController(length: 3, vsync: this);
+  }
+
+  @override
+  void didUpdateWidget(BooksScreen oldWidget) {
+    super.didUpdateWidget(oldWidget);
+
+    switch (widget.kind) {
+      case 'popular':
+        _tabController.index = 0;
+        break;
+
+      case 'new':
+        _tabController.index = 1;
+        break;
+
+      case 'all':
+        _tabController.index = 2;
+        break;
+    }
+  }
+
+  @override
+  void dispose() {
+    _tabController.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(
+          title: const Text('Books'),
+          bottom: TabBar(
+            controller: _tabController,
+            onTap: _handleTabTapped,
+            tabs: const <Tab>[
+              Tab(
+                text: 'Popular',
+                icon: Icon(Icons.people),
+              ),
+              Tab(
+                text: 'New',
+                icon: Icon(Icons.new_releases),
+              ),
+              Tab(
+                text: 'All',
+                icon: Icon(Icons.list),
+              ),
+            ],
+          ),
+        ),
+        body: TabBarView(
+          controller: _tabController,
+          children: <Widget>[
+            BookList(
+              books: libraryInstance.popularBooks,
+              onTap: _handleBookTapped,
+            ),
+            BookList(
+              books: libraryInstance.newBooks,
+              onTap: _handleBookTapped,
+            ),
+            BookList(
+              books: libraryInstance.allBooks,
+              onTap: _handleBookTapped,
+            ),
+          ],
+        ),
+      );
+
+  void _handleBookTapped(Book book) {
+    context.go('/book/${book.id}');
+  }
+
+  void _handleTabTapped(int index) {
+    switch (index) {
+      case 1:
+        context.go('/books/new');
+        break;
+      case 2:
+        context.go('/books/all');
+        break;
+      case 0:
+      default:
+        context.go('/books/popular');
+        break;
+    }
+  }
+}

lib/13/go/books/src/screens/scaffold.dart

@@ -0,0 +1,71 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:adaptive_navigation/adaptive_navigation.dart';
+import 'package:flutter/material.dart';
+
+import 'package:go_router/go_router.dart';
+
+/// The enum for scaffold tab.
+enum ScaffoldTab {
+  /// The books tab.
+  books,
+
+  /// The authors tab.
+  authors,
+
+  /// The settings tab.
+  settings
+}
+
+/// The scaffold for the book store.
+class BookstoreScaffold extends StatelessWidget {
+  /// Creates a [BookstoreScaffold].
+  const BookstoreScaffold({
+    required this.selectedTab,
+    required this.child,
+    super.key,
+  });
+
+  /// Which tab of the scaffold to display.
+  final ScaffoldTab selectedTab;
+
+  /// The scaffold body.
+  final Widget child;
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        body: AdaptiveNavigationScaffold(
+          selectedIndex: selectedTab.index,
+          body: child,
+          onDestinationSelected: (int idx) {
+            switch (ScaffoldTab.values[idx]) {
+              case ScaffoldTab.books:
+                context.go('/books');
+                break;
+              case ScaffoldTab.authors:
+                context.go('/authors');
+                break;
+              case ScaffoldTab.settings:
+                context.go('/settings');
+                break;
+            }
+          },
+          destinations: const <AdaptiveScaffoldDestination>[
+            AdaptiveScaffoldDestination(
+              title: 'Books',
+              icon: Icons.book,
+            ),
+            AdaptiveScaffoldDestination(
+              title: 'Authors',
+              icon: Icons.person,
+            ),
+            AdaptiveScaffoldDestination(
+              title: 'Settings',
+              icon: Icons.settings,
+            ),
+          ],
+        ),
+      );
+}

lib/13/go/books/src/screens/settings.dart

@@ -0,0 +1,101 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:url_launcher/link.dart';
+
+import '../auth.dart';
+
+/// The settings screen.
+class SettingsScreen extends StatefulWidget {
+  /// Creates a [SettingsScreen].
+  const SettingsScreen({super.key});
+
+  @override
+  State<SettingsScreen> createState() => _SettingsScreenState();
+}
+
+class _SettingsScreenState extends State<SettingsScreen> {
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        body: SafeArea(
+          child: SingleChildScrollView(
+            child: Align(
+              alignment: Alignment.topCenter,
+              child: ConstrainedBox(
+                constraints: const BoxConstraints(maxWidth: 400),
+                child: const Card(
+                  child: Padding(
+                    padding: EdgeInsets.symmetric(vertical: 18, horizontal: 12),
+                    child: SettingsContent(),
+                  ),
+                ),
+              ),
+            ),
+          ),
+        ),
+      );
+}
+
+/// The content of a [SettingsScreen].
+class SettingsContent extends StatelessWidget {
+  /// Creates a [SettingsContent].
+  const SettingsContent({
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) => Column(
+        children: <Widget>[
+          ...<Widget>[
+            Text(
+              'Settings',
+              style: Theme.of(context).textTheme.headlineMedium,
+            ),
+            ElevatedButton(
+              onPressed: () {
+                BookstoreAuthScope.of(context).signOut();
+              },
+              child: const Text('Sign out'),
+            ),
+            Link(
+              uri: Uri.parse('/book/0'),
+              builder: (BuildContext context, FollowLink? followLink) =>
+                  TextButton(
+                onPressed: followLink,
+                child: const Text('Go directly to /book/0 (Link)'),
+              ),
+            ),
+            TextButton(
+              onPressed: () {
+                context.go('/book/0');
+              },
+              child: const Text('Go directly to /book/0 (GoRouter)'),
+            ),
+          ].map<Widget>((Widget w) =>
+              Padding(padding: const EdgeInsets.all(8), child: w)),
+          TextButton(
+            onPressed: () => showDialog<String>(
+              context: context,
+              builder: (BuildContext context) => AlertDialog(
+                title: const Text('Alert!'),
+                content: const Text('The alert description goes here.'),
+                actions: <Widget>[
+                  TextButton(
+                    onPressed: () => Navigator.pop(context, 'Cancel'),
+                    child: const Text('Cancel'),
+                  ),
+                  TextButton(
+                    onPressed: () => Navigator.pop(context, 'OK'),
+                    child: const Text('OK'),
+                  ),
+                ],
+              ),
+            ),
+            child: const Text('Show Dialog'),
+          )
+        ],
+      );
+}

lib/13/go/books/src/screens/sign_in.dart

@@ -0,0 +1,77 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+/// Credential data class.
+class Credentials {
+  /// Creates a credential data object.
+  Credentials(this.username, this.password);
+
+  /// The username of the credentials.
+  final String username;
+
+  /// The password of the credentials.
+  final String password;
+}
+
+/// The sign-in screen.
+class SignInScreen extends StatefulWidget {
+  /// Creates a sign-in screen.
+  const SignInScreen({
+    required this.onSignIn,
+    super.key,
+  });
+
+  /// Called when users sign in with [Credentials].
+  final ValueChanged<Credentials> onSignIn;
+
+  @override
+  State<SignInScreen> createState() => _SignInScreenState();
+}
+
+class _SignInScreenState extends State<SignInScreen> {
+  final TextEditingController _usernameController = TextEditingController();
+  final TextEditingController _passwordController = TextEditingController();
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        body: Center(
+          child: Card(
+            child: Container(
+              constraints: BoxConstraints.loose(const Size(600, 600)),
+              padding: const EdgeInsets.all(8),
+              child: Column(
+                mainAxisAlignment: MainAxisAlignment.center,
+                mainAxisSize: MainAxisSize.min,
+                children: <Widget>[
+                  Text('Sign in',
+                      style: Theme.of(context).textTheme.headlineMedium),
+                  TextField(
+                    decoration: const InputDecoration(labelText: 'Username'),
+                    controller: _usernameController,
+                  ),
+                  TextField(
+                    decoration: const InputDecoration(labelText: 'Password'),
+                    obscureText: true,
+                    controller: _passwordController,
+                  ),
+                  Padding(
+                    padding: const EdgeInsets.all(16),
+                    child: TextButton(
+                      onPressed: () async {
+                        widget.onSignIn(Credentials(
+                            _usernameController.value.text,
+                            _passwordController.value.text));
+                      },
+                      child: const Text('Sign in'),
+                    ),
+                  ),
+                ],
+              ),
+            ),
+          ),
+        ),
+      );
+}

lib/13/go/books/src/widgets/author_list.dart

@@ -0,0 +1,37 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+import '../data.dart';
+
+/// The author list view.
+class AuthorList extends StatelessWidget {
+  /// Creates an [AuthorList].
+  const AuthorList({
+    required this.authors,
+    this.onTap,
+    super.key,
+  });
+
+  /// The list of authors to be shown.
+  final List<Author> authors;
+
+  /// Called when the user taps an author.
+  final ValueChanged<Author>? onTap;
+
+  @override
+  Widget build(BuildContext context) => ListView.builder(
+        itemCount: authors.length,
+        itemBuilder: (BuildContext context, int index) => ListTile(
+          title: Text(
+            authors[index].name,
+          ),
+          subtitle: Text(
+            '${authors[index].books.length} books',
+          ),
+          onTap: onTap != null ? () => onTap!(authors[index]) : null,
+        ),
+      );
+}

lib/13/go/books/src/widgets/book_list.dart

@@ -0,0 +1,37 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+import '../data.dart';
+
+/// The book list view.
+class BookList extends StatelessWidget {
+  /// Creates an [BookList].
+  const BookList({
+    required this.books,
+    this.onTap,
+    super.key,
+  });
+
+  /// The list of books to be displayed.
+  final List<Book> books;
+
+  /// Called when the user taps a book.
+  final ValueChanged<Book>? onTap;
+
+  @override
+  Widget build(BuildContext context) => ListView.builder(
+        itemCount: books.length,
+        itemBuilder: (BuildContext context, int index) => ListTile(
+          title: Text(
+            books[index].title,
+          ),
+          subtitle: Text(
+            books[index].author.name,
+          ),
+          onTap: onTap != null ? () => onTap!(books[index]) : null,
+        ),
+      );
+}

lib/13/go/exception_handling.dart

@@ -0,0 +1,87 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+/// This sample app shows how to use `GoRouter.onException` to redirect on
+/// exception.
+///
+/// The first route '/' is mapped to [HomeScreen], and the second route
+/// '/404' is mapped to [NotFoundScreen].
+///
+/// Any other unknown route or exception is redirected to `/404`.
+void main() => runApp(const MyApp());
+
+/// The route configuration.
+final GoRouter _router = GoRouter(
+  onException: (_, GoRouterState state, GoRouter router) {
+    router.go('/404', extra: state.uri.toString());
+  },
+  routes: <RouteBase>[
+    GoRoute(
+      path: '/',
+      builder: (BuildContext context, GoRouterState state) {
+        return const HomeScreen();
+      },
+    ),
+    GoRoute(
+      path: '/404',
+      builder: (BuildContext context, GoRouterState state) {
+        return NotFoundScreen(uri: state.extra as String? ?? '');
+      },
+    ),
+  ],
+);
+
+/// The main app.
+class MyApp extends StatelessWidget {
+  /// Constructs a [MyApp]
+  const MyApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp.router(
+      routerConfig: _router,
+    );
+  }
+}
+
+/// The home screen
+class HomeScreen extends StatelessWidget {
+  /// Constructs a [HomeScreen]
+  const HomeScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Home Screen')),
+      body: Center(
+        child: ElevatedButton(
+          onPressed: () => context.go('/some-unknown-route'),
+          child: const Text('Simulates user entering unknown url'),
+        ),
+      ),
+    );
+  }
+}
+
+/// The not found screen
+class NotFoundScreen extends StatelessWidget {
+  /// Constructs a [HomeScreen]
+  const NotFoundScreen({super.key, required this.uri});
+
+  /// The uri that can not be found.
+  final String uri;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Page Not Found')),
+      body: Center(
+        child: Text("Can't find a page for: $uri"),
+      ),
+    );
+  }
+}

lib/13/go/main.dart

@@ -0,0 +1,87 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+/// This sample app shows an app with two screens.
+///
+/// The first route '/' is mapped to [HomeScreen], and the second route
+/// '/details' is mapped to [DetailsScreen].
+///
+/// The buttons use context.go() to navigate to each destination. On mobile
+/// devices, each destination is deep-linkable and on the web, can be navigated
+/// to using the address bar.
+void main() => runApp(const MyApp());
+
+/// The route configuration.
+final GoRouter _router = GoRouter(
+  routes: <RouteBase>[
+    GoRoute(
+      path: '/',
+      builder: (BuildContext context, GoRouterState state) {
+        return const HomeScreen();
+      },
+      routes: <RouteBase>[
+        GoRoute(
+          path: 'details',
+          builder: (BuildContext context, GoRouterState state) {
+            return const DetailsScreen();
+          },
+        ),
+      ],
+    ),
+  ],
+);
+
+/// The main app.
+class MyApp extends StatelessWidget {
+  /// Constructs a [MyApp]
+  const MyApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp.router(
+      routerConfig: _router,
+    );
+  }
+}
+
+/// The home screen
+class HomeScreen extends StatelessWidget {
+  /// Constructs a [HomeScreen]
+  const HomeScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Home Screen')),
+      body: Center(
+        child: ElevatedButton(
+          onPressed: () => context.go('/details'),
+          child: const Text('Go to the Details screen'),
+        ),
+      ),
+    );
+  }
+}
+
+/// The details screen
+class DetailsScreen extends StatelessWidget {
+  /// Constructs a [DetailsScreen]
+  const DetailsScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Details Screen')),
+      body: Center(
+        child: ElevatedButton(
+          onPressed: () => context.go('/'),
+          child: const Text('Go back to the Home screen'),
+        ),
+      ),
+    );
+  }
+}

lib/13/go/named_routes.dart

@@ -0,0 +1,181 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+// This scenario demonstrates how to navigate using named locations instead of
+// URLs.
+//
+// Instead of hardcoding the URI locations , you can also use the named
+// locations. To use this API, give a unique name to each GoRoute. The name can
+// then be used in context.namedLocation to be translate back to the actual URL
+// location.
+
+/// Family data class.
+class Family {
+  /// Create a family.
+  const Family({required this.name, required this.people});
+
+  /// The last name of the family.
+  final String name;
+
+  /// The people in the family.
+  final Map<String, Person> people;
+}
+
+/// Person data class.
+class Person {
+  /// Creates a person.
+  const Person({required this.name, required this.age});
+
+  /// The first name of the person.
+  final String name;
+
+  /// The age of the person.
+  final int age;
+}
+
+const Map<String, Family> _families = <String, Family>{
+  'f1': Family(
+    name: 'Doe',
+    people: <String, Person>{
+      'p1': Person(name: 'Jane', age: 23),
+      'p2': Person(name: 'John', age: 6),
+    },
+  ),
+  'f2': Family(
+    name: 'Wong',
+    people: <String, Person>{
+      'p1': Person(name: 'June', age: 51),
+      'p2': Person(name: 'Xin', age: 44),
+    },
+  ),
+};
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Named Routes';
+
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+        debugShowCheckedModeBanner: false,
+      );
+
+  late final GoRouter _router = GoRouter(
+    debugLogDiagnostics: true,
+    routes: <GoRoute>[
+      GoRoute(
+        name: 'home',
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const HomeScreen(),
+        routes: <GoRoute>[
+          GoRoute(
+            name: 'family',
+            path: 'family/:fid',
+            builder: (BuildContext context, GoRouterState state) =>
+                FamilyScreen(fid: state.pathParameters['fid']!),
+            routes: <GoRoute>[
+              GoRoute(
+                name: 'person',
+                path: 'person/:pid',
+                builder: (BuildContext context, GoRouterState state) {
+                  return PersonScreen(
+                      fid: state.pathParameters['fid']!,
+                      pid: state.pathParameters['pid']!);
+                },
+              ),
+            ],
+          ),
+        ],
+      ),
+    ],
+  );
+}
+
+/// The home screen that shows a list of families.
+class HomeScreen extends StatelessWidget {
+  /// Creates a [HomeScreen].
+  const HomeScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text(App.title),
+      ),
+      body: ListView(
+        children: <Widget>[
+          for (final MapEntry<String, Family> entry in _families.entries)
+            ListTile(
+              title: Text(entry.value.name),
+              onTap: () => context.go(context.namedLocation('family',
+                  pathParameters: <String, String>{'fid': entry.key})),
+            )
+        ],
+      ),
+    );
+  }
+}
+
+/// The screen that shows a list of persons in a family.
+class FamilyScreen extends StatelessWidget {
+  /// Creates a [FamilyScreen].
+  const FamilyScreen({required this.fid, super.key});
+
+  /// The id family to display.
+  final String fid;
+
+  @override
+  Widget build(BuildContext context) {
+    final Map<String, Person> people = _families[fid]!.people;
+    return Scaffold(
+      appBar: AppBar(title: Text(_families[fid]!.name)),
+      body: ListView(
+        children: <Widget>[
+          for (final MapEntry<String, Person> entry in people.entries)
+            ListTile(
+              title: Text(entry.value.name),
+              onTap: () => context.go(context.namedLocation(
+                'person',
+                pathParameters: <String, String>{'fid': fid, 'pid': entry.key},
+                queryParameters: <String, String>{'qid': 'quid'},
+              )),
+            ),
+        ],
+      ),
+    );
+  }
+}
+
+/// The person screen.
+class PersonScreen extends StatelessWidget {
+  /// Creates a [PersonScreen].
+  const PersonScreen({required this.fid, required this.pid, super.key});
+
+  /// The id of family this person belong to.
+  final String fid;
+
+  /// The id of the person to be displayed.
+  final String pid;
+
+  @override
+  Widget build(BuildContext context) {
+    final Family family = _families[fid]!;
+    final Person person = family.people[pid]!;
+    return Scaffold(
+      appBar: AppBar(title: Text(person.name)),
+      body: Text('${person.name} ${family.name} is ${person.age} years old'),
+    );
+  }
+}

lib/13/go/others/custom_stateful_shell_route.dart

@@ -0,0 +1,460 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:collection/collection.dart';
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+final GlobalKey<NavigatorState> _rootNavigatorKey =
+    GlobalKey<NavigatorState>(debugLabel: 'root');
+final GlobalKey<NavigatorState> _tabANavigatorKey =
+    GlobalKey<NavigatorState>(debugLabel: 'tabANav');
+
+// This example demonstrates how to setup nested navigation using a
+// BottomNavigationBar, where each bar item uses its own persistent navigator,
+// i.e. navigation state is maintained separately for each item. This setup also
+// enables deep linking into nested pages.
+//
+// This example also demonstrates how build a nested shell with a custom
+// container for the branch Navigators (in this case a TabBarView).
+
+void main() {
+  runApp(NestedTabNavigationExampleApp());
+}
+
+/// An example demonstrating how to use nested navigators
+class NestedTabNavigationExampleApp extends StatelessWidget {
+  /// Creates a NestedTabNavigationExampleApp
+  NestedTabNavigationExampleApp({super.key});
+
+  final GoRouter _router = GoRouter(
+    navigatorKey: _rootNavigatorKey,
+    initialLocation: '/a',
+    routes: <RouteBase>[
+      StatefulShellRoute(
+        builder: (BuildContext context, GoRouterState state,
+            StatefulNavigationShell navigationShell) {
+          // This nested StatefulShellRoute demonstrates the use of a
+          // custom container for the branch Navigators. In this implementation,
+          // no customization is done in the builder function (navigationShell
+          // itself is simply used as the Widget for the route). Instead, the
+          // navigatorContainerBuilder function below is provided to
+          // customize the container for the branch Navigators.
+          return navigationShell;
+        },
+        navigatorContainerBuilder: (BuildContext context,
+            StatefulNavigationShell navigationShell, List<Widget> children) {
+          // Returning a customized container for the branch
+          // Navigators (i.e. the `List<Widget> children` argument).
+          //
+          // See ScaffoldWithNavBar for more details on how the children
+          // are managed (using AnimatedBranchContainer).
+          return ScaffoldWithNavBar(
+              navigationShell: navigationShell, children: children);
+        },
+        branches: <StatefulShellBranch>[
+          // The route branch for the first tab of the bottom navigation bar.
+          StatefulShellBranch(
+            navigatorKey: _tabANavigatorKey,
+            routes: <RouteBase>[
+              GoRoute(
+                // The screen to display as the root in the first tab of the
+                // bottom navigation bar.
+                path: '/a',
+                builder: (BuildContext context, GoRouterState state) =>
+                    const RootScreenA(),
+                routes: <RouteBase>[
+                  // The details screen to display stacked on navigator of the
+                  // first tab. This will cover screen A but not the application
+                  // shell (bottom navigation bar).
+                  GoRoute(
+                    path: 'details',
+                    builder: (BuildContext context, GoRouterState state) =>
+                        const DetailsScreen(label: 'A'),
+                  ),
+                ],
+              ),
+            ],
+          ),
+
+          // The route branch for the third tab of the bottom navigation bar.
+          StatefulShellBranch(
+            // StatefulShellBranch will automatically use the first descendant
+            // GoRoute as the initial location of the branch. If another route
+            // is desired, specify the location of it using the defaultLocation
+            // parameter.
+            // defaultLocation: '/c2',
+            routes: <RouteBase>[
+              StatefulShellRoute(
+                builder: (BuildContext context, GoRouterState state,
+                    StatefulNavigationShell navigationShell) {
+                  // Just like with the top level StatefulShellRoute, no
+                  // customization is done in the builder function.
+                  return navigationShell;
+                },
+                navigatorContainerBuilder: (BuildContext context,
+                    StatefulNavigationShell navigationShell,
+                    List<Widget> children) {
+                  // Returning a customized container for the branch
+                  // Navigators (i.e. the `List<Widget> children` argument).
+                  //
+                  // See TabbedRootScreen for more details on how the children
+                  // are managed (in a TabBarView).
+                  return TabbedRootScreen(
+                      navigationShell: navigationShell, children: children);
+                },
+                // This bottom tab uses a nested shell, wrapping sub routes in a
+                // top TabBar.
+                branches: <StatefulShellBranch>[
+                  StatefulShellBranch(routes: <GoRoute>[
+                    GoRoute(
+                      path: '/b1',
+                      builder: (BuildContext context, GoRouterState state) =>
+                          const TabScreen(
+                              label: 'B1', detailsPath: '/b1/details'),
+                      routes: <RouteBase>[
+                        GoRoute(
+                          path: 'details',
+                          builder:
+                              (BuildContext context, GoRouterState state) =>
+                                  const DetailsScreen(
+                            label: 'B1',
+                            withScaffold: false,
+                          ),
+                        ),
+                      ],
+                    ),
+                  ]),
+                  StatefulShellBranch(routes: <GoRoute>[
+                    GoRoute(
+                      path: '/b2',
+                      builder: (BuildContext context, GoRouterState state) =>
+                          const TabScreen(
+                              label: 'B2', detailsPath: '/b2/details'),
+                      routes: <RouteBase>[
+                        GoRoute(
+                          path: 'details',
+                          builder:
+                              (BuildContext context, GoRouterState state) =>
+                                  const DetailsScreen(
+                            label: 'B2',
+                            withScaffold: false,
+                          ),
+                        ),
+                      ],
+                    ),
+                  ]),
+                ],
+              ),
+            ],
+          ),
+        ],
+      ),
+    ],
+  );
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp.router(
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      routerConfig: _router,
+    );
+  }
+}
+
+/// Builds the "shell" for the app by building a Scaffold with a
+/// BottomNavigationBar, where [child] is placed in the body of the Scaffold.
+class ScaffoldWithNavBar extends StatelessWidget {
+  /// Constructs an [ScaffoldWithNavBar].
+  const ScaffoldWithNavBar({
+    required this.navigationShell,
+    required this.children,
+    Key? key,
+  }) : super(key: key ?? const ValueKey<String>('ScaffoldWithNavBar'));
+
+  /// The navigation shell and container for the branch Navigators.
+  final StatefulNavigationShell navigationShell;
+
+  /// The children (branch Navigators) to display in a custom container
+  /// ([AnimatedBranchContainer]).
+  final List<Widget> children;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: AnimatedBranchContainer(
+        currentIndex: navigationShell.currentIndex,
+        children: children,
+      ),
+      bottomNavigationBar: BottomNavigationBar(
+        // Here, the items of BottomNavigationBar are hard coded. In a real
+        // world scenario, the items would most likely be generated from the
+        // branches of the shell route, which can be fetched using
+        // `navigationShell.route.branches`.
+        items: const <BottomNavigationBarItem>[
+          BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Section A'),
+          BottomNavigationBarItem(icon: Icon(Icons.work), label: 'Section B'),
+        ],
+        currentIndex: navigationShell.currentIndex,
+        onTap: (int index) => _onTap(context, index),
+      ),
+    );
+  }
+
+  /// Navigate to the current location of the branch at the provided index when
+  /// tapping an item in the BottomNavigationBar.
+  void _onTap(BuildContext context, int index) {
+    // When navigating to a new branch, it's recommended to use the goBranch
+    // method, as doing so makes sure the last navigation state of the
+    // Navigator for the branch is restored.
+    navigationShell.goBranch(
+      index,
+      // A common pattern when using bottom navigation bars is to support
+      // navigating to the initial location when tapping the item that is
+      // already active. This example demonstrates how to support this behavior,
+      // using the initialLocation parameter of goBranch.
+      initialLocation: index == navigationShell.currentIndex,
+    );
+  }
+}
+
+/// Custom branch Navigator container that provides animated transitions
+/// when switching branches.
+class AnimatedBranchContainer extends StatelessWidget {
+  /// Creates a AnimatedBranchContainer
+  const AnimatedBranchContainer(
+      {super.key, required this.currentIndex, required this.children});
+
+  /// The index (in [children]) of the branch Navigator to display.
+  final int currentIndex;
+
+  /// The children (branch Navigators) to display in this container.
+  final List<Widget> children;
+
+  @override
+  Widget build(BuildContext context) {
+    return Stack(
+        children: children.mapIndexed(
+      (int index, Widget navigator) {
+        return AnimatedScale(
+          scale: index == currentIndex ? 1 : 1.5,
+          duration: const Duration(milliseconds: 400),
+          child: AnimatedOpacity(
+            opacity: index == currentIndex ? 1 : 0,
+            duration: const Duration(milliseconds: 400),
+            child: _branchNavigatorWrapper(index, navigator),
+          ),
+        );
+      },
+    ).toList());
+  }
+
+  Widget _branchNavigatorWrapper(int index, Widget navigator) => IgnorePointer(
+        ignoring: index != currentIndex,
+        child: TickerMode(
+          enabled: index == currentIndex,
+          child: navigator,
+        ),
+      );
+}
+
+/// Widget for the root page for the first section of the bottom navigation bar.
+class RootScreenA extends StatelessWidget {
+  /// Creates a RootScreenA
+  const RootScreenA({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text('Root of section A'),
+      ),
+      body: Center(
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: <Widget>[
+            Text('Screen A', style: Theme.of(context).textTheme.titleLarge),
+            const Padding(padding: EdgeInsets.all(4)),
+            TextButton(
+              onPressed: () {
+                GoRouter.of(context).go('/a/details');
+              },
+              child: const Text('View details'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+/// The details screen for either the A or B screen.
+class DetailsScreen extends StatefulWidget {
+  /// Constructs a [DetailsScreen].
+  const DetailsScreen({
+    required this.label,
+    this.param,
+    this.withScaffold = true,
+    super.key,
+  });
+
+  /// The label to display in the center of the screen.
+  final String label;
+
+  /// Optional param
+  final String? param;
+
+  /// Wrap in scaffold
+  final bool withScaffold;
+
+  @override
+  State<StatefulWidget> createState() => DetailsScreenState();
+}
+
+/// The state for DetailsScreen
+class DetailsScreenState extends State<DetailsScreen> {
+  int _counter = 0;
+
+  @override
+  Widget build(BuildContext context) {
+    if (widget.withScaffold) {
+      return Scaffold(
+        appBar: AppBar(
+          title: Text('Details Screen - ${widget.label}'),
+        ),
+        body: _build(context),
+      );
+    } else {
+      return Container(
+        color: Theme.of(context).scaffoldBackgroundColor,
+        child: _build(context),
+      );
+    }
+  }
+
+  Widget _build(BuildContext context) {
+    return Center(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: <Widget>[
+          Text('Details for ${widget.label} - Counter: $_counter',
+              style: Theme.of(context).textTheme.titleLarge),
+          const Padding(padding: EdgeInsets.all(4)),
+          TextButton(
+            onPressed: () {
+              setState(() {
+                _counter++;
+              });
+            },
+            child: const Text('Increment counter'),
+          ),
+          const Padding(padding: EdgeInsets.all(8)),
+          if (widget.param != null)
+            Text('Parameter: ${widget.param!}',
+                style: Theme.of(context).textTheme.titleMedium),
+          const Padding(padding: EdgeInsets.all(8)),
+          if (!widget.withScaffold) ...<Widget>[
+            const Padding(padding: EdgeInsets.all(16)),
+            TextButton(
+              onPressed: () {
+                GoRouter.of(context).pop();
+              },
+              child: const Text('< Back',
+                  style: TextStyle(fontWeight: FontWeight.bold, fontSize: 18)),
+            ),
+          ]
+        ],
+      ),
+    );
+  }
+}
+
+/// Builds a nested shell using a [TabBar] and [TabBarView].
+class TabbedRootScreen extends StatefulWidget {
+  /// Constructs a TabbedRootScreen
+  const TabbedRootScreen(
+      {required this.navigationShell, required this.children, super.key});
+
+  /// The current state of the parent StatefulShellRoute.
+  final StatefulNavigationShell navigationShell;
+
+  /// The children (branch Navigators) to display in the [TabBarView].
+  final List<Widget> children;
+
+  @override
+  State<StatefulWidget> createState() => _TabbedRootScreenState();
+}
+
+class _TabbedRootScreenState extends State<TabbedRootScreen>
+    with SingleTickerProviderStateMixin {
+  late final TabController _tabController = TabController(
+      length: widget.children.length,
+      vsync: this,
+      initialIndex: widget.navigationShell.currentIndex);
+
+  @override
+  void didUpdateWidget(covariant TabbedRootScreen oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    _tabController.index = widget.navigationShell.currentIndex;
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final List<Tab> tabs = widget.children
+        .mapIndexed((int i, _) => Tab(text: 'Tab ${i + 1}'))
+        .toList();
+
+    return Scaffold(
+      appBar: AppBar(
+          title: const Text('Root of Section B (nested TabBar shell)'),
+          bottom: TabBar(
+            controller: _tabController,
+            tabs: tabs,
+            onTap: (int tappedIndex) => _onTabTap(context, tappedIndex),
+          )),
+      body: TabBarView(
+        controller: _tabController,
+        children: widget.children,
+      ),
+    );
+  }
+
+  void _onTabTap(BuildContext context, int index) {
+    widget.navigationShell.goBranch(index);
+  }
+}
+
+/// Widget for the pages in the top tab bar.
+class TabScreen extends StatelessWidget {
+  /// Creates a RootScreen
+  const TabScreen({required this.label, required this.detailsPath, super.key});
+
+  /// The label
+  final String label;
+
+  /// The path to the detail page
+  final String detailsPath;
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: <Widget>[
+          Text('Screen $label', style: Theme.of(context).textTheme.titleLarge),
+          const Padding(padding: EdgeInsets.all(4)),
+          TextButton(
+            onPressed: () {
+              GoRouter.of(context).go(detailsPath);
+            },
+            child: const Text('View details'),
+          ),
+        ],
+      ),
+    );
+  }
+}

lib/13/go/others/error_screen.dart

@@ -0,0 +1,110 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Custom Error Screen';
+
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+      );
+
+  final GoRouter _router = GoRouter(
+    routes: <GoRoute>[
+      GoRoute(
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page1Screen(),
+      ),
+      GoRoute(
+        path: '/page2',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page2Screen(),
+      ),
+    ],
+    errorBuilder: (BuildContext context, GoRouterState state) =>
+        ErrorScreen(state.error!),
+  );
+}
+
+/// The screen of the first page.
+class Page1Screen extends StatelessWidget {
+  /// Creates a [Page1Screen].
+  const Page1Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.go('/page2'),
+                child: const Text('Go to page 2'),
+              ),
+            ],
+          ),
+        ),
+      );
+}
+
+/// The screen of the second page.
+class Page2Screen extends StatelessWidget {
+  /// Creates a [Page2Screen].
+  const Page2Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.go('/'),
+                child: const Text('Go to home page'),
+              ),
+            ],
+          ),
+        ),
+      );
+}
+
+/// The screen of the error page.
+class ErrorScreen extends StatelessWidget {
+  /// Creates an [ErrorScreen].
+  const ErrorScreen(this.error, {super.key});
+
+  /// The error to display.
+  final Exception error;
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text('My "Page Not Found" Screen')),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              SelectableText(error.toString()),
+              TextButton(
+                onPressed: () => context.go('/'),
+                child: const Text('Home'),
+              ),
+            ],
+          ),
+        ),
+      );
+}

lib/13/go/others/extra_param.dart

@@ -0,0 +1,133 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+/// Family data class.
+class Family {
+  /// Create a family.
+  const Family({required this.name, required this.people});
+
+  /// The last name of the family.
+  final String name;
+
+  /// The people in the family.
+  final Map<String, Person> people;
+}
+
+/// Person data class.
+class Person {
+  /// Creates a person.
+  const Person({required this.name, required this.age});
+
+  /// The first name of the person.
+  final String name;
+
+  /// The age of the person.
+  final int age;
+}
+
+const Map<String, Family> _families = <String, Family>{
+  'f1': Family(
+    name: 'Doe',
+    people: <String, Person>{
+      'p1': Person(name: 'Jane', age: 23),
+      'p2': Person(name: 'John', age: 6),
+    },
+  ),
+  'f2': Family(
+    name: 'Wong',
+    people: <String, Person>{
+      'p1': Person(name: 'June', age: 51),
+      'p2': Person(name: 'Xin', age: 44),
+    },
+  ),
+};
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Extra Parameter';
+
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+      );
+
+  late final GoRouter _router = GoRouter(
+    routes: <GoRoute>[
+      GoRoute(
+        name: 'home',
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const HomeScreen(),
+        routes: <GoRoute>[
+          GoRoute(
+            name: 'family',
+            path: 'family',
+            builder: (BuildContext context, GoRouterState state) {
+              final Map<String, Object> params =
+                  state.extra! as Map<String, String>;
+              final String fid = params['fid']! as String;
+              return FamilyScreen(fid: fid);
+            },
+          ),
+        ],
+      ),
+    ],
+  );
+}
+
+/// The home screen that shows a list of families.
+class HomeScreen extends StatelessWidget {
+  /// Creates a [HomeScreen].
+  const HomeScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: ListView(
+          children: <Widget>[
+            for (final MapEntry<String, Family> entry in _families.entries)
+              ListTile(
+                title: Text(entry.value.name),
+                onTap: () => context.goNamed('family',
+                    extra: <String, String>{'fid': entry.key}),
+              )
+          ],
+        ),
+      );
+}
+
+/// The screen that shows a list of persons in a family.
+class FamilyScreen extends StatelessWidget {
+  /// Creates a [FamilyScreen].
+  const FamilyScreen({required this.fid, super.key});
+
+  /// The family to display.
+  final String fid;
+
+  @override
+  Widget build(BuildContext context) {
+    final Map<String, Person> people = _families[fid]!.people;
+    return Scaffold(
+      appBar: AppBar(title: Text(_families[fid]!.name)),
+      body: ListView(
+        children: <Widget>[
+          for (final Person p in people.values)
+            ListTile(
+              title: Text(p.name),
+            ),
+        ],
+      ),
+    );
+  }
+}

lib/13/go/others/init_loc.dart

@@ -0,0 +1,110 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Initial Location';
+
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+      );
+
+  final GoRouter _router = GoRouter(
+    initialLocation: '/page3',
+    routes: <GoRoute>[
+      GoRoute(
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page1Screen(),
+      ),
+      GoRoute(
+        path: '/page2',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page2Screen(),
+      ),
+      GoRoute(
+        path: '/page3',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page3Screen(),
+      ),
+    ],
+  );
+}
+
+/// The screen of the first page.
+class Page1Screen extends StatelessWidget {
+  /// Creates a [Page1Screen].
+  const Page1Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.go('/page2'),
+                child: const Text('Go to page 2'),
+              ),
+            ],
+          ),
+        ),
+      );
+}
+
+/// The screen of the second page.
+class Page2Screen extends StatelessWidget {
+  /// Creates a [Page2Screen].
+  const Page2Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.go('/'),
+                child: const Text('Go to home page'),
+              ),
+            ],
+          ),
+        ),
+      );
+}
+
+/// The screen of the third page.
+class Page3Screen extends StatelessWidget {
+  /// Creates a [Page3Screen].
+  const Page3Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.go('/page2'),
+                child: const Text('Go to page 2'),
+              ),
+            ],
+          ),
+        ),
+      );
+}

lib/13/go/others/nav_observer.dart

@@ -0,0 +1,167 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:logging/logging.dart';
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Navigator Observer';
+
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+      );
+
+  final GoRouter _router = GoRouter(
+    observers: <NavigatorObserver>[MyNavObserver()],
+    routes: <GoRoute>[
+      GoRoute(
+        // if there's no name, path will be used as name for observers
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page1Screen(),
+        routes: <GoRoute>[
+          GoRoute(
+            name: 'page2',
+            path: 'page2/:p1',
+            builder: (BuildContext context, GoRouterState state) =>
+                const Page2Screen(),
+            routes: <GoRoute>[
+              GoRoute(
+                name: 'page3',
+                path: 'page3',
+                builder: (BuildContext context, GoRouterState state) =>
+                    const Page3Screen(),
+              ),
+            ],
+          ),
+        ],
+      ),
+    ],
+  );
+}
+
+/// The Navigator observer.
+class MyNavObserver extends NavigatorObserver {
+  /// Creates a [MyNavObserver].
+  MyNavObserver() {
+    log.onRecord.listen((LogRecord e) => debugPrint('$e'));
+  }
+
+  /// The logged message.
+  final Logger log = Logger('MyNavObserver');
+
+  @override
+  void didPush(Route<dynamic> route, Route<dynamic>? previousRoute) =>
+      log.info('didPush: ${route.str}, previousRoute= ${previousRoute?.str}');
+
+  @override
+  void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) =>
+      log.info('didPop: ${route.str}, previousRoute= ${previousRoute?.str}');
+
+  @override
+  void didRemove(Route<dynamic> route, Route<dynamic>? previousRoute) =>
+      log.info('didRemove: ${route.str}, previousRoute= ${previousRoute?.str}');
+
+  @override
+  void didReplace({Route<dynamic>? newRoute, Route<dynamic>? oldRoute}) =>
+      log.info('didReplace: new= ${newRoute?.str}, old= ${oldRoute?.str}');
+
+  @override
+  void didStartUserGesture(
+    Route<dynamic> route,
+    Route<dynamic>? previousRoute,
+  ) =>
+      log.info('didStartUserGesture: ${route.str}, '
+          'previousRoute= ${previousRoute?.str}');
+
+  @override
+  void didStopUserGesture() => log.info('didStopUserGesture');
+}
+
+extension on Route<dynamic> {
+  String get str => 'route(${settings.name}: ${settings.arguments})';
+}
+
+/// The screen of the first page.
+class Page1Screen extends StatelessWidget {
+  /// Creates a [Page1Screen].
+  const Page1Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.goNamed(
+                  'page2',
+                  pathParameters: <String, String>{'p1': 'pv1'},
+                  queryParameters: <String, String>{'q1': 'qv1'},
+                ),
+                child: const Text('Go to page 2'),
+              ),
+            ],
+          ),
+        ),
+      );
+}
+
+/// The screen of the second page.
+class Page2Screen extends StatelessWidget {
+  /// Creates a [Page2Screen].
+  const Page2Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.goNamed(
+                  'page3',
+                  pathParameters: <String, String>{'p1': 'pv2'},
+                ),
+                child: const Text('Go to page 3'),
+              ),
+            ],
+          ),
+        ),
+      );
+}
+
+/// The screen of the third page.
+class Page3Screen extends StatelessWidget {
+  /// Creates a [Page3Screen].
+  const Page3Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.go('/'),
+                child: const Text('Go to home page'),
+              ),
+            ],
+          ),
+        ),
+      );
+}

lib/13/go/others/push.dart

@@ -0,0 +1,101 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Push';
+
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+      );
+
+  late final GoRouter _router = GoRouter(
+    routes: <GoRoute>[
+      GoRoute(
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page1ScreenWithPush(),
+      ),
+      GoRoute(
+        path: '/page2',
+        builder: (BuildContext context, GoRouterState state) =>
+            Page2ScreenWithPush(
+          int.parse(state.uri.queryParameters['push-count']!),
+        ),
+      ),
+    ],
+  );
+}
+
+/// The screen of the first page.
+class Page1ScreenWithPush extends StatelessWidget {
+  /// Creates a [Page1ScreenWithPush].
+  const Page1ScreenWithPush({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text('${App.title}: page 1')),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.push('/page2?push-count=1'),
+                child: const Text('Push page 2'),
+              ),
+            ],
+          ),
+        ),
+      );
+}
+
+/// The screen of the second page.
+class Page2ScreenWithPush extends StatelessWidget {
+  /// Creates a [Page2ScreenWithPush].
+  const Page2ScreenWithPush(this.pushCount, {super.key});
+
+  /// The push count.
+  final int pushCount;
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(
+          title: Text('${App.title}: page 2 w/ push count $pushCount'),
+        ),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              Padding(
+                padding: const EdgeInsets.all(8),
+                child: ElevatedButton(
+                  onPressed: () => context.go('/'),
+                  child: const Text('Go to home page'),
+                ),
+              ),
+              Padding(
+                padding: const EdgeInsets.all(8),
+                child: ElevatedButton(
+                  onPressed: () => context.push(
+                    '/page2?push-count=${pushCount + 1}',
+                  ),
+                  child: const Text('Push page 2 (again)'),
+                ),
+              ),
+            ],
+          ),
+        ),
+      );
+}

lib/13/go/others/router_neglect.dart

@@ -0,0 +1,95 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Router neglect';
+
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+      );
+
+  final GoRouter _router = GoRouter(
+    // turn off history tracking in the browser for this navigation
+    routerNeglect: true,
+    routes: <GoRoute>[
+      GoRoute(
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page1Screen(),
+      ),
+      GoRoute(
+        path: '/page2',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page2Screen(),
+      ),
+    ],
+  );
+}
+
+/// The screen of the first page.
+class Page1Screen extends StatelessWidget {
+  /// Creates a [Page1Screen].
+  const Page1Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.go('/page2'),
+                child: const Text('Go to page 2'),
+              ),
+              const SizedBox(height: 8),
+              ElevatedButton(
+                // turn off history tracking in the browser for this navigation;
+                // note that this isn't necessary when you've set routerNeglect
+                // but it does illustrate the technique
+                onPressed: () => Router.neglect(
+                  context,
+                  () => context.push('/page2'),
+                ),
+                child: const Text('Push page 2'),
+              ),
+            ],
+          ),
+        ),
+      );
+}
+
+/// The screen of the second page.
+class Page2Screen extends StatelessWidget {
+  /// Creates a [Page2Screen].
+  const Page2Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.go('/'),
+                child: const Text('Go to home page'),
+              ),
+            ],
+          ),
+        ),
+      );
+}

lib/13/go/others/state_restoration.dart

@@ -0,0 +1,102 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+void main() => runApp(
+      const RootRestorationScope(restorationId: 'root', child: App()),
+    );
+
+/// The main app.
+class App extends StatefulWidget {
+  /// Creates an [App].
+  const App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: State Restoration';
+
+  @override
+  State<App> createState() => _AppState();
+}
+
+class _AppState extends State<App> with RestorationMixin {
+  @override
+  String get restorationId => 'wrapper';
+
+  @override
+  void restoreState(RestorationBucket? oldBucket, bool initialRestore) {
+    // Implement restoreState for your app
+  }
+
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: App.title,
+        restorationScopeId: 'app',
+      );
+
+  final GoRouter _router = GoRouter(
+    routes: <GoRoute>[
+      // restorationId set for the route automatically
+      GoRoute(
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page1Screen(),
+      ),
+
+      // restorationId set for the route automatically
+      GoRoute(
+        path: '/page2',
+        builder: (BuildContext context, GoRouterState state) =>
+            const Page2Screen(),
+      ),
+    ],
+    restorationScopeId: 'router',
+  );
+}
+
+/// The screen of the first page.
+class Page1Screen extends StatelessWidget {
+  /// Creates a [Page1Screen].
+  const Page1Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.go('/page2'),
+                child: const Text('Go to page 2'),
+              ),
+            ],
+          ),
+        ),
+      );
+}
+
+/// The screen of the second page.
+class Page2Screen extends StatelessWidget {
+  /// Creates a [Page2Screen].
+  const Page2Screen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: <Widget>[
+              ElevatedButton(
+                onPressed: () => context.go('/'),
+                child: const Text('Go to home page'),
+              ),
+            ],
+          ),
+        ),
+      );
+}

lib/13/go/others/stateful_shell_state_restoration.dart

@@ -0,0 +1,236 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+void main() => runApp(RestorableStatefulShellRouteExampleApp());
+
+/// An example demonstrating how to use StatefulShellRoute with state
+/// restoration.
+class RestorableStatefulShellRouteExampleApp extends StatelessWidget {
+  /// Creates a NestedTabNavigationExampleApp
+  RestorableStatefulShellRouteExampleApp({super.key});
+
+  final GoRouter _router = GoRouter(
+    initialLocation: '/a',
+    restorationScopeId: 'router',
+    routes: <RouteBase>[
+      StatefulShellRoute.indexedStack(
+        restorationScopeId: 'shell1',
+        pageBuilder: (BuildContext context, GoRouterState state,
+            StatefulNavigationShell navigationShell) {
+          return MaterialPage<void>(
+              restorationId: 'shellWidget1',
+              child: ScaffoldWithNavBar(navigationShell: navigationShell));
+        },
+        branches: <StatefulShellBranch>[
+          // The route branch for the first tab of the bottom navigation bar.
+          StatefulShellBranch(
+            restorationScopeId: 'branchA',
+            routes: <RouteBase>[
+              GoRoute(
+                // The screen to display as the root in the first tab of the
+                // bottom navigation bar.
+                path: '/a',
+                pageBuilder: (BuildContext context, GoRouterState state) =>
+                    const MaterialPage<void>(
+                        restorationId: 'screenA',
+                        child:
+                            RootScreen(label: 'A', detailsPath: '/a/details')),
+                routes: <RouteBase>[
+                  // The details screen to display stacked on navigator of the
+                  // first tab. This will cover screen A but not the application
+                  // shell (bottom navigation bar).
+                  GoRoute(
+                    path: 'details',
+                    pageBuilder: (BuildContext context, GoRouterState state) =>
+                        const MaterialPage<void>(
+                            restorationId: 'screenADetail',
+                            child: DetailsScreen(label: 'A')),
+                  ),
+                ],
+              ),
+            ],
+          ),
+          // The route branch for the second tab of the bottom navigation bar.
+          StatefulShellBranch(
+            restorationScopeId: 'branchB',
+            routes: <RouteBase>[
+              GoRoute(
+                // The screen to display as the root in the second tab of the
+                // bottom navigation bar.
+                path: '/b',
+                pageBuilder: (BuildContext context, GoRouterState state) =>
+                    const MaterialPage<void>(
+                        restorationId: 'screenB',
+                        child:
+                            RootScreen(label: 'B', detailsPath: '/b/details')),
+                routes: <RouteBase>[
+                  // The details screen to display stacked on navigator of the
+                  // first tab. This will cover screen A but not the application
+                  // shell (bottom navigation bar).
+                  GoRoute(
+                    path: 'details',
+                    pageBuilder: (BuildContext context, GoRouterState state) =>
+                        const MaterialPage<void>(
+                            restorationId: 'screenBDetail',
+                            child: DetailsScreen(label: 'B')),
+                  ),
+                ],
+              ),
+            ],
+          ),
+        ],
+      ),
+    ],
+  );
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp.router(
+      restorationScopeId: 'app',
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      routerConfig: _router,
+    );
+  }
+}
+
+/// Builds the "shell" for the app by building a Scaffold with a
+/// BottomNavigationBar, where [child] is placed in the body of the Scaffold.
+class ScaffoldWithNavBar extends StatelessWidget {
+  /// Constructs an [ScaffoldWithNavBar].
+  const ScaffoldWithNavBar({
+    required this.navigationShell,
+    Key? key,
+  }) : super(key: key ?? const ValueKey<String>('ScaffoldWithNavBar'));
+
+  /// The navigation shell and container for the branch Navigators.
+  final StatefulNavigationShell navigationShell;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: navigationShell,
+      bottomNavigationBar: BottomNavigationBar(
+        items: const <BottomNavigationBarItem>[
+          BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Section A'),
+          BottomNavigationBarItem(icon: Icon(Icons.work), label: 'Section B'),
+        ],
+        currentIndex: navigationShell.currentIndex,
+        onTap: (int tappedIndex) => navigationShell.goBranch(tappedIndex),
+      ),
+    );
+  }
+}
+
+/// Widget for the root/initial pages in the bottom navigation bar.
+class RootScreen extends StatelessWidget {
+  /// Creates a RootScreen
+  const RootScreen({
+    required this.label,
+    required this.detailsPath,
+    super.key,
+  });
+
+  /// The label
+  final String label;
+
+  /// The path to the detail page
+  final String detailsPath;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('Root of section $label'),
+      ),
+      body: Center(
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: <Widget>[
+            Text('Screen $label',
+                style: Theme.of(context).textTheme.titleLarge),
+            const Padding(padding: EdgeInsets.all(4)),
+            TextButton(
+              onPressed: () {
+                GoRouter.of(context).go(detailsPath);
+              },
+              child: const Text('View details'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+/// The details screen for either the A or B screen.
+class DetailsScreen extends StatefulWidget {
+  /// Constructs a [DetailsScreen].
+  const DetailsScreen({
+    required this.label,
+    super.key,
+  });
+
+  /// The label to display in the center of the screen.
+  final String label;
+
+  @override
+  State<StatefulWidget> createState() => DetailsScreenState();
+}
+
+/// The state for DetailsScreen
+class DetailsScreenState extends State<DetailsScreen> with RestorationMixin {
+  final RestorableInt _counter = RestorableInt(0);
+
+  @override
+  String? get restorationId => 'DetailsScreen-${widget.label}';
+
+  @override
+  void restoreState(RestorationBucket? oldBucket, bool initialRestore) {
+    registerForRestoration(_counter, 'counter');
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
+    _counter.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('Details Screen - ${widget.label}'),
+      ),
+      body: _build(context),
+    );
+  }
+
+  Widget _build(BuildContext context) {
+    return Center(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: <Widget>[
+          Text('Details for ${widget.label} - Counter: ${_counter.value}',
+              style: Theme.of(context).textTheme.titleLarge),
+          const Padding(padding: EdgeInsets.all(4)),
+          TextButton(
+            onPressed: () {
+              setState(() {
+                _counter.value++;
+              });
+            },
+            child: const Text('Increment counter'),
+          ),
+          const Padding(padding: EdgeInsets.all(8)),
+        ],
+      ),
+    );
+  }
+}

lib/13/go/others/transitions.dart

@@ -0,0 +1,163 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Custom Transitions';
+
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+      );
+
+  final GoRouter _router = GoRouter(
+    routes: <GoRoute>[
+      GoRoute(
+        path: '/',
+        redirect: (_, __) => '/none',
+      ),
+      GoRoute(
+        path: '/fade',
+        pageBuilder: (BuildContext context, GoRouterState state) =>
+            CustomTransitionPage<void>(
+          key: state.pageKey,
+          child: const ExampleTransitionsScreen(
+            kind: 'fade',
+            color: Colors.red,
+          ),
+          transitionsBuilder: (BuildContext context,
+                  Animation<double> animation,
+                  Animation<double> secondaryAnimation,
+                  Widget child) =>
+              FadeTransition(opacity: animation, child: child),
+        ),
+      ),
+      GoRoute(
+        path: '/scale',
+        pageBuilder: (BuildContext context, GoRouterState state) =>
+            CustomTransitionPage<void>(
+          key: state.pageKey,
+          child: const ExampleTransitionsScreen(
+            kind: 'scale',
+            color: Colors.green,
+          ),
+          transitionsBuilder: (BuildContext context,
+                  Animation<double> animation,
+                  Animation<double> secondaryAnimation,
+                  Widget child) =>
+              ScaleTransition(scale: animation, child: child),
+        ),
+      ),
+      GoRoute(
+        path: '/slide',
+        pageBuilder: (BuildContext context, GoRouterState state) =>
+            CustomTransitionPage<void>(
+          key: state.pageKey,
+          child: const ExampleTransitionsScreen(
+            kind: 'slide',
+            color: Colors.yellow,
+          ),
+          transitionsBuilder: (BuildContext context,
+                  Animation<double> animation,
+                  Animation<double> secondaryAnimation,
+                  Widget child) =>
+              SlideTransition(
+            position: animation.drive(
+              Tween<Offset>(
+                begin: const Offset(0.25, 0.25),
+                end: Offset.zero,
+              ).chain(CurveTween(curve: Curves.easeIn)),
+            ),
+            child: child,
+          ),
+        ),
+      ),
+      GoRoute(
+        path: '/rotation',
+        pageBuilder: (BuildContext context, GoRouterState state) =>
+            CustomTransitionPage<void>(
+          key: state.pageKey,
+          child: const ExampleTransitionsScreen(
+            kind: 'rotation',
+            color: Colors.purple,
+          ),
+          transitionsBuilder: (BuildContext context,
+                  Animation<double> animation,
+                  Animation<double> secondaryAnimation,
+                  Widget child) =>
+              RotationTransition(turns: animation, child: child),
+        ),
+      ),
+      GoRoute(
+        path: '/none',
+        pageBuilder: (BuildContext context, GoRouterState state) =>
+            NoTransitionPage<void>(
+          key: state.pageKey,
+          child: const ExampleTransitionsScreen(
+            kind: 'none',
+            color: Colors.white,
+          ),
+        ),
+      ),
+    ],
+  );
+}
+
+/// An Example transitions screen.
+class ExampleTransitionsScreen extends StatelessWidget {
+  /// Creates an [ExampleTransitionsScreen].
+  const ExampleTransitionsScreen({
+    required this.color,
+    required this.kind,
+    super.key,
+  });
+
+  /// The available transition kinds.
+  static final List<String> kinds = <String>[
+    'fade',
+    'scale',
+    'slide',
+    'rotation',
+    'none'
+  ];
+
+  /// The color of the container.
+  final Color color;
+
+  /// The transition kind.
+  final String kind;
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: Text('${App.title}: $kind')),
+        body: Container(
+          color: color,
+          child: Center(
+            child: Column(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: <Widget>[
+                for (final String kind in kinds)
+                  Padding(
+                    padding: const EdgeInsets.all(8),
+                    child: ElevatedButton(
+                      onPressed: () => context.go('/$kind'),
+                      child: Text('$kind transition'),
+                    ),
+                  )
+              ],
+            ),
+          ),
+        ),
+      );
+}

lib/13/go/path_and_query_parameters.dart

@@ -0,0 +1,169 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+// This scenario demonstrates how to use path parameters and query parameters.
+//
+// The route segments that start with ':' are treated as path parameters when
+// defining GoRoute[s]. The parameter values can be accessed through
+// GoRouterState.pathParameters.
+//
+// The query parameters are automatically stored in GoRouterState.queryParameters.
+
+/// Family data class.
+class Family {
+  /// Create a family.
+  const Family({required this.name, required this.people});
+
+  /// The last name of the family.
+  final String name;
+
+  /// The people in the family.
+  final Map<String, Person> people;
+}
+
+/// Person data class.
+class Person {
+  /// Creates a person.
+  const Person({required this.name, required this.age});
+
+  /// The first name of the person.
+  final String name;
+
+  /// The age of the person.
+  final int age;
+}
+
+const Map<String, Family> _families = <String, Family>{
+  'f1': Family(
+    name: 'Doe',
+    people: <String, Person>{
+      'p1': Person(name: 'Jane', age: 23),
+      'p2': Person(name: 'John', age: 6),
+    },
+  ),
+  'f2': Family(
+    name: 'Wong',
+    people: <String, Person>{
+      'p1': Person(name: 'June', age: 51),
+      'p2': Person(name: 'Xin', age: 44),
+    },
+  ),
+};
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Query Parameters';
+
+  // add the login info into the tree as app state that can change over time
+  @override
+  Widget build(BuildContext context) => MaterialApp.router(
+        routerConfig: _router,
+        title: title,
+        debugShowCheckedModeBanner: false,
+      );
+
+  late final GoRouter _router = GoRouter(
+    routes: <GoRoute>[
+      GoRoute(
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const HomeScreen(),
+        routes: <GoRoute>[
+          GoRoute(
+              name: 'family',
+              path: 'family/:fid',
+              builder: (BuildContext context, GoRouterState state) {
+                return FamilyScreen(
+                  fid: state.pathParameters['fid']!,
+                  asc: state.uri.queryParameters['sort'] == 'asc',
+                );
+              }),
+        ],
+      ),
+    ],
+  );
+}
+
+/// The home screen that shows a list of families.
+class HomeScreen extends StatelessWidget {
+  /// Creates a [HomeScreen].
+  const HomeScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text(App.title),
+      ),
+      body: ListView(
+        children: <Widget>[
+          for (final MapEntry<String, Family> entry in _families.entries)
+            ListTile(
+              title: Text(entry.value.name),
+              onTap: () => context.go('/family/${entry.key}'),
+            )
+        ],
+      ),
+    );
+  }
+}
+
+/// The screen that shows a list of persons in a family.
+class FamilyScreen extends StatelessWidget {
+  /// Creates a [FamilyScreen].
+  const FamilyScreen({required this.fid, required this.asc, super.key});
+
+  /// The family to display.
+  final String fid;
+
+  /// Whether to sort the name in ascending order.
+  final bool asc;
+
+  @override
+  Widget build(BuildContext context) {
+    final Map<String, String> newQueries;
+    final List<String> names = _families[fid]!
+        .people
+        .values
+        .map<String>((Person p) => p.name)
+        .toList();
+    names.sort();
+    if (asc) {
+      newQueries = const <String, String>{'sort': 'desc'};
+    } else {
+      newQueries = const <String, String>{'sort': 'asc'};
+    }
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(_families[fid]!.name),
+        actions: <Widget>[
+          IconButton(
+            onPressed: () => context.goNamed('family',
+                pathParameters: <String, String>{'fid': fid},
+                queryParameters: newQueries),
+            tooltip: 'sort ascending or descending',
+            icon: const Icon(Icons.sort),
+          )
+        ],
+      ),
+      body: ListView(
+        children: <Widget>[
+          for (final String name in asc ? names : names.reversed)
+            ListTile(
+              title: Text(name),
+            ),
+        ],
+      ),
+    );
+  }
+}

lib/13/go/raw_book/main.dart

@@ -0,0 +1,27 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:io' show Platform;
+
+import 'package:flutter/foundation.dart' show kIsWeb;
+import 'package:flutter/material.dart';
+import 'package:url_strategy/url_strategy.dart';
+// import 'package:window_size/window_size.dart';
+
+import 'src/app.dart';
+
+void main() {
+  // Use package:url_strategy until this pull request is released:
+  // https://github.com/flutter/flutter/pull/77103
+
+  // Use to setHashUrlStrategy() to use "/#/" in the address bar (default). Use
+  // setPathUrlStrategy() to use the path. You may need to configure your web
+  // server to redirect all paths to index.html.
+  //
+  // On mobile platforms, both functions are no-ops.
+  setHashUrlStrategy();
+  // setPathUrlStrategy();
+  runApp(const Bookstore());
+}
+

lib/13/go/raw_book/src/app.dart

@@ -0,0 +1,81 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+import 'auth.dart';
+import 'routing.dart';
+import 'screens/navigator.dart';
+
+class Bookstore extends StatefulWidget {
+  const Bookstore({super.key});
+
+  @override
+  State<Bookstore> createState() => _BookstoreState();
+}
+
+class _BookstoreState extends State<Bookstore> {
+  late final RouteState _routeState;
+  late final SimpleRouterDelegate _routerDelegate;
+  late final TemplateRouteParser _routeParser;
+
+  @override
+  void initState() {
+    /// Configure the parser with all of the app's allowed path templates.
+    _routeParser = TemplateRouteParser(
+      allowedPaths: [
+        '/signin',
+        '/authors',
+        '/settings',
+        '/books/new',
+        '/books/all',
+        '/books/popular',
+        '/book/:bookId',
+        '/author/:authorId',
+      ],
+      initialRoute: '/signin',
+    );
+
+    _routeState = RouteState(_routeParser);
+
+    _routerDelegate = SimpleRouterDelegate(
+      routeState: _routeState,
+    );
+
+
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) => RouteStateScope(
+        notifier: _routeState,
+        child: MaterialApp.router(
+            routerDelegate: _routerDelegate,
+            routeInformationParser: _routeParser,
+            // Revert back to pre-Flutter-2.5 transition behavior:
+            // https://github.com/flutter/flutter/issues/82053
+            theme: ThemeData(
+              useMaterial3: true,
+              pageTransitionsTheme: const PageTransitionsTheme(
+                builders: {
+                  TargetPlatform.android: FadeUpwardsPageTransitionsBuilder(),
+                  TargetPlatform.iOS: CupertinoPageTransitionsBuilder(),
+                  TargetPlatform.linux: FadeUpwardsPageTransitionsBuilder(),
+                  TargetPlatform.macOS: CupertinoPageTransitionsBuilder(),
+                  TargetPlatform.windows: FadeUpwardsPageTransitionsBuilder(),
+                },
+              ),
+            ),
+
+        ),
+      );
+
+
+  @override
+  void dispose() {
+    _routeState.dispose();
+    _routerDelegate.dispose();
+    super.dispose();
+  }
+}

lib/13/go/raw_book/src/auth.dart

@@ -0,0 +1,47 @@
+// // Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// // for details. All rights reserved. Use of this source code is governed by a
+// // BSD-style license that can be found in the LICENSE file.
+//
+// import 'package:flutter/widgets.dart';
+//
+// /// A mock authentication service
+// class BookstoreAuth extends ChangeNotifier {
+//   bool _signedIn = false;
+//
+//   bool get signedIn => _signedIn;
+//
+//   Future<void> signOut() async {
+//     await Future<void>.delayed(const Duration(milliseconds: 200));
+//     // Sign out.
+//     _signedIn = false;
+//     notifyListeners();
+//   }
+//
+//   Future<bool> signIn(String username, String password) async {
+//     await Future<void>.delayed(const Duration(milliseconds: 200));
+//
+//     // Sign in. Allow any password.
+//     _signedIn = true;
+//     notifyListeners();
+//     return _signedIn;
+//   }
+//
+//   @override
+//   bool operator ==(Object other) =>
+//       other is BookstoreAuth && other._signedIn == _signedIn;
+//
+//   @override
+//   int get hashCode => _signedIn.hashCode;
+// }
+//
+// class BookstoreAuthScope extends InheritedNotifier<BookstoreAuth> {
+//   const BookstoreAuthScope({
+//     required super.notifier,
+//     required super.child,
+//     super.key,
+//   });
+//
+//   static BookstoreAuth of(BuildContext context) => context
+//       .dependOnInheritedWidgetOfExactType<BookstoreAuthScope>()!
+//       .notifier!;
+// }

lib/13/go/raw_book/src/data.dart

@@ -0,0 +1,7 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+export 'data/author.dart';
+export 'data/book.dart';
+export 'data/library.dart';

lib/13/go/raw_book/src/data/author.dart

@@ -0,0 +1,13 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'book.dart';
+
+class Author {
+  final int id;
+  final String name;
+  final books = <Book>[];
+
+  Author(this.id, this.name);
+}

lib/13/go/raw_book/src/data/book.dart

@@ -0,0 +1,15 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'author.dart';
+
+class Book {
+  final int id;
+  final String title;
+  final Author author;
+  final bool isPopular;
+  final bool isNew;
+
+  Book(this.id, this.title, this.isPopular, this.isNew, this.author);
+}

lib/13/go/raw_book/src/data/library.dart

@@ -0,0 +1,61 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'author.dart';
+import 'book.dart';
+
+final libraryInstance = Library()
+  ..addBook(
+      title: 'Left Hand of Darkness',
+      authorName: 'Ursula K. Le Guin',
+      isPopular: true,
+      isNew: true)
+  ..addBook(
+      title: 'Too Like the Lightning',
+      authorName: 'Ada Palmer',
+      isPopular: false,
+      isNew: true)
+  ..addBook(
+      title: 'Kindred',
+      authorName: 'Octavia E. Butler',
+      isPopular: true,
+      isNew: false)
+  ..addBook(
+      title: 'The Lathe of Heaven',
+      authorName: 'Ursula K. Le Guin',
+      isPopular: false,
+      isNew: false);
+
+class Library {
+  final List<Book> allBooks = [];
+  final List<Author> allAuthors = [];
+
+  void addBook({
+    required String title,
+    required String authorName,
+    required bool isPopular,
+    required bool isNew,
+  }) {
+    var author = allAuthors.firstWhere(
+      (author) => author.name == authorName,
+      orElse: () {
+        final value = Author(allAuthors.length, authorName);
+        allAuthors.add(value);
+        return value;
+      },
+    );
+    var book = Book(allBooks.length, title, isPopular, isNew, author);
+
+    author.books.add(book);
+    allBooks.add(book);
+  }
+
+  List<Book> get popularBooks => [
+        ...allBooks.where((book) => book.isPopular),
+      ];
+
+  List<Book> get newBooks => [
+        ...allBooks.where((book) => book.isNew),
+      ];
+}

lib/13/go/raw_book/src/routing.dart

@@ -0,0 +1,8 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+export 'routing/delegate.dart';
+export 'routing/parsed_route.dart';
+export 'routing/parser.dart';
+export 'routing/route_state.dart';

lib/13/go/raw_book/src/routing/delegate.dart

@@ -0,0 +1,47 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/widgets.dart';
+
+import '../screens/navigator.dart';
+import 'parsed_route.dart';
+import 'route_state.dart';
+
+class SimpleRouterDelegate extends RouterDelegate<ParsedRoute>
+    with ChangeNotifier, PopNavigatorRouterDelegateMixin<ParsedRoute> {
+  final RouteState routeState;
+
+  @override
+  final GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
+
+  SimpleRouterDelegate({
+    required this.routeState,
+  }) {
+    routeState.addListener(notifyListeners);
+  }
+
+  @override
+  Widget build(BuildContext context) => BookstoreNavigator(
+    navigatorKey: navigatorKey,
+  );
+
+  @override
+  Future<void> setNewRoutePath(ParsedRoute configuration) async {
+    routeState.route = configuration;
+    return SynchronousFuture(null);
+  }
+
+  @override
+  ParsedRoute get currentConfiguration => routeState.route;
+
+  @override
+  void dispose() {
+    routeState.removeListener(notifyListeners);
+    routeState.dispose();
+    super.dispose();
+  }
+}

lib/13/go/raw_book/src/routing/parsed_route.dart

@@ -0,0 +1,51 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:collection/collection.dart';
+import 'package:quiver/core.dart';
+
+import 'parser.dart';
+
+/// A route path that has been parsed by [TemplateRouteParser].
+class ParsedRoute {
+  /// The current path location without query parameters. (/book/123)
+  final String path;
+
+  /// The path template (/book/:id)
+  final String pathTemplate;
+
+  /// The path parameters ({id: 123})
+  final Map<String, String> parameters;
+
+  /// The query parameters ({search: abc})
+  final Map<String, String> queryParameters;
+
+  static const _mapEquality = MapEquality<String, String>();
+
+  ParsedRoute(
+      this.path, this.pathTemplate, this.parameters, this.queryParameters);
+
+  @override
+  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(
+        path,
+        pathTemplate,
+        _mapEquality.hash(parameters),
+        _mapEquality.hash(queryParameters),
+      );
+
+  @override
+  String toString() => '<ParsedRoute '
+      'template: $pathTemplate '
+      'path: $path '
+      'parameters: $parameters '
+      'query parameters: $queryParameters>';
+}

lib/13/go/raw_book/src/routing/parser.dart

@@ -0,0 +1,62 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/widgets.dart';
+import 'package:path_to_regexp/path_to_regexp.dart';
+
+import 'parsed_route.dart';
+
+/// Used by [TemplateRouteParser] to guard access to routes.
+typedef RouteGuard<T> = Future<T> Function(T from);
+
+/// Parses the URI path into a [ParsedRoute].
+class TemplateRouteParser extends RouteInformationParser<ParsedRoute> {
+  final List<String> _pathTemplates;
+  final ParsedRoute initialRoute;
+
+  TemplateRouteParser({
+    /// The list of allowed path templates (['/', '/users/:id'])
+    required List<String> allowedPaths,
+
+    /// The initial route
+    String initialRoute = '/',
+
+  })  : initialRoute = ParsedRoute(initialRoute, initialRoute, {}, {}),
+        _pathTemplates = [
+          ...allowedPaths,
+        ],
+        assert(allowedPaths.contains(initialRoute));
+
+  @override
+  Future<ParsedRoute> parseRouteInformation(
+    RouteInformation routeInformation,
+  ) async {
+    print("=======parseRouteInformation:${routeInformation.uri.path}===================");
+
+    final uri = routeInformation.uri;
+    final path = uri.toString();
+    final queryParams = uri.queryParameters;
+    var parsedRoute = initialRoute;
+
+    for (var pathTemplate in _pathTemplates) {
+      final parameters = <String>[];
+      var pathRegExp = pathToRegExp(pathTemplate, parameters: parameters);
+      if (pathRegExp.hasMatch(path)) {
+        final match = pathRegExp.matchAsPrefix(path);
+        if (match == null) continue;
+        final params = extract(parameters, match);
+        parsedRoute = ParsedRoute(path, pathTemplate, params, queryParams);
+      }
+    }
+
+    return parsedRoute;
+  }
+
+  @override
+  RouteInformation restoreRouteInformation(ParsedRoute configuration) {
+    print("=======restoreRouteInformation:${configuration}===================");
+
+    return RouteInformation(uri: Uri.parse(configuration.path));
+  }
+}

lib/13/go/raw_book/src/routing/route_state.dart

@@ -0,0 +1,48 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/widgets.dart';
+
+import 'parsed_route.dart';
+import 'parser.dart';
+
+/// The current route state. To change the current route, call obtain the state
+/// using `RouteStateScope.of(context)` and call `go()`:
+///
+/// ```
+/// RouteStateScope.of(context).go('/book/2');
+/// ```
+class RouteState extends ChangeNotifier {
+  final TemplateRouteParser _parser;
+  ParsedRoute _route;
+
+  RouteState(this._parser) : _route = _parser.initialRoute;
+
+  ParsedRoute get route => _route;
+
+  set route(ParsedRoute route) {
+    // Don't notify listeners if the path hasn't changed.
+    if (_route == route) return;
+
+    _route = route;
+    notifyListeners();
+  }
+
+  Future<void> go(String route) async {
+    this.route = await _parser
+        .parseRouteInformation(RouteInformation(uri: Uri.parse(route)));
+  }
+}
+
+/// Provides the current [RouteState] to descendant widgets in the tree.
+class RouteStateScope extends InheritedNotifier<RouteState> {
+  const RouteStateScope({
+    required super.notifier,
+    required super.child,
+    super.key,
+  });
+
+  static RouteState of(BuildContext context) =>
+      context.dependOnInheritedWidgetOfExactType<RouteStateScope>()!.notifier!;
+}

lib/13/go/raw_book/src/screens/author_details.dart

@@ -0,0 +1,39 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+import '../data.dart';
+import '../routing.dart';
+import '../widgets/book_list.dart';
+
+class AuthorDetailsScreen extends StatelessWidget {
+  final Author author;
+
+  const AuthorDetailsScreen({
+    super.key,
+    required this.author,
+  });
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(
+          title: Text(author.name),
+        ),
+        body: Center(
+          child: Column(
+            children: [
+              Expanded(
+                child: BookList(
+                  books: author.books,
+                  onTap: (book) {
+                    RouteStateScope.of(context).go('/book/${book.id}');
+                  },
+                ),
+              ),
+            ],
+          ),
+        ),
+      );
+}

lib/13/go/raw_book/src/screens/authors.dart

@@ -0,0 +1,28 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+import '../data/library.dart';
+import '../routing.dart';
+import '../widgets/author_list.dart';
+
+class AuthorsScreen extends StatelessWidget {
+  final String title = 'Authors';
+
+  const AuthorsScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(
+          title: Text(title),
+        ),
+        body: AuthorList(
+          authors: libraryInstance.allAuthors,
+          onTap: (author) {
+            RouteStateScope.of(context).go('/author/${author.id}');
+          },
+        ),
+      );
+}

lib/13/go/raw_book/src/screens/book_details.dart

@@ -0,0 +1,66 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:url_launcher/link.dart';
+
+import '../data.dart';
+import 'author_details.dart';
+
+class BookDetailsScreen extends StatelessWidget {
+  final Book? book;
+
+  const BookDetailsScreen({
+    super.key,
+    this.book,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    if (book == null) {
+      return const Scaffold(
+        body: Center(
+          child: Text('No book found.'),
+        ),
+      );
+    }
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(book!.title),
+      ),
+      body: Center(
+        child: Column(
+          children: [
+            Text(
+              book!.title,
+              style: Theme.of(context).textTheme.headlineMedium,
+            ),
+            Text(
+              book!.author.name,
+              style: Theme.of(context).textTheme.titleMedium,
+            ),
+            TextButton(
+              child: const Text('View author (Push)'),
+              onPressed: () {
+                Navigator.of(context).push<void>(
+                  MaterialPageRoute<void>(
+                    builder: (context) =>
+                        AuthorDetailsScreen(author: book!.author),
+                  ),
+                );
+              },
+            ),
+            Link(
+              uri: Uri.parse('/author/${book!.author.id}'),
+              builder: (context, followLink) => TextButton(
+                onPressed: followLink,
+                child: const Text('View author (Link)'),
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

lib/13/go/raw_book/src/screens/books.dart

@@ -0,0 +1,111 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+import '../data.dart';
+import '../routing.dart';
+import '../widgets/book_list.dart';
+
+class BooksScreen extends StatefulWidget {
+  const BooksScreen({
+    super.key,
+  });
+
+  @override
+  State<BooksScreen> createState() => _BooksScreenState();
+}
+
+class _BooksScreenState extends State<BooksScreen>
+    with SingleTickerProviderStateMixin {
+  late TabController _tabController;
+
+  @override
+  void initState() {
+    super.initState();
+    _tabController = TabController(length: 3, vsync: this)
+      ..addListener(_handleTabIndexChanged);
+  }
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+
+    final newPath = _routeState.route.pathTemplate;
+    if (newPath.startsWith('/books/popular')) {
+      _tabController.index = 0;
+    } else if (newPath.startsWith('/books/new')) {
+      _tabController.index = 1;
+    } else if (newPath == '/books/all') {
+      _tabController.index = 2;
+    }
+  }
+
+  @override
+  void dispose() {
+    _tabController.removeListener(_handleTabIndexChanged);
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(
+          title: const Text('Books'),
+          elevation: 8,
+          bottom: TabBar(
+            controller: _tabController,
+            tabs: const [
+              Tab(
+                text: 'Popular',
+                icon: Icon(Icons.people),
+              ),
+              Tab(
+                text: 'New',
+                icon: Icon(Icons.new_releases),
+              ),
+              Tab(
+                text: 'All',
+                icon: Icon(Icons.list),
+              ),
+            ],
+          ),
+        ),
+        body: TabBarView(
+          controller: _tabController,
+          children: [
+            BookList(
+              books: libraryInstance.popularBooks,
+              onTap: _handleBookTapped,
+            ),
+            BookList(
+              books: libraryInstance.newBooks,
+              onTap: _handleBookTapped,
+            ),
+            BookList(
+              books: libraryInstance.allBooks,
+              onTap: _handleBookTapped,
+            ),
+          ],
+        ),
+      );
+
+  RouteState get _routeState => RouteStateScope.of(context);
+
+  void _handleBookTapped(Book book) {
+    _routeState.go('/book/${book.id}');
+  }
+
+  void _handleTabIndexChanged() {
+    switch (_tabController.index) {
+      case 1:
+        _routeState.go('/books/new');
+      case 2:
+        _routeState.go('/books/all');
+      case 0:
+      default:
+        _routeState.go('/books/popular');
+        break;
+    }
+  }
+}

lib/13/go/raw_book/src/screens/navigator.dart

@@ -0,0 +1,108 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:collection/collection.dart';
+import 'package:flutter/material.dart';
+
+import '../auth.dart';
+import '../data.dart';
+import '../routing.dart';
+import '../screens/sign_in.dart';
+import '../widgets/fade_transition_page.dart';
+import 'author_details.dart';
+import 'book_details.dart';
+import 'scaffold.dart';
+
+/// Builds the top-level navigator for the app. The pages to display are based
+/// on the `routeState` that was parsed by the TemplateRouteParser.
+class BookstoreNavigator extends StatefulWidget {
+  final GlobalKey<NavigatorState> navigatorKey;
+
+  const BookstoreNavigator({
+    required this.navigatorKey,
+    super.key,
+  });
+
+  @override
+  State<BookstoreNavigator> createState() => _BookstoreNavigatorState();
+}
+
+class _BookstoreNavigatorState extends State<BookstoreNavigator> {
+  final _signInKey = const ValueKey('Sign in');
+  final _scaffoldKey = const ValueKey('App scaffold');
+  final _bookDetailsKey = const ValueKey('Book details screen');
+  final _authorDetailsKey = const ValueKey('Author details screen');
+
+  @override
+  Widget build(BuildContext context) {
+    final routeState = RouteStateScope.of(context);
+    final pathTemplate = routeState.route.pathTemplate;
+
+    Book? selectedBook;
+    if (pathTemplate == '/book/:bookId') {
+      selectedBook = libraryInstance.allBooks.firstWhereOrNull(
+          (b) => b.id.toString() == routeState.route.parameters['bookId']);
+    }
+
+    Author? selectedAuthor;
+    if (pathTemplate == '/author/:authorId') {
+      selectedAuthor = libraryInstance.allAuthors.firstWhereOrNull(
+          (b) => b.id.toString() == routeState.route.parameters['authorId']);
+    }
+
+    return Navigator(
+      key: widget.navigatorKey,
+      onPopPage: (route, dynamic result) {
+        // 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) {
+          routeState.go('/books/popular');
+        }
+
+        if (route.settings is Page &&
+            (route.settings as Page).key == _authorDetailsKey) {
+          routeState.go('/authors');
+        }
+
+        return route.didPop(result);
+      },
+      pages: [
+        if (routeState.route.pathTemplate == '/signin')
+          // Display the sign in screen.
+          FadeTransitionPage<void>(
+            key: _signInKey,
+            child: SignInScreen(
+              onSignIn: (credentials) async {
+                await routeState.go('/books/popular');
+              },
+            ),
+          )
+        else ...[
+          // Display the app
+          FadeTransitionPage<void>(
+            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,
+              child: BookDetailsScreen(
+                book: selectedBook,
+              ),
+            )
+          else if (selectedAuthor != null)
+            MaterialPage<void>(
+              key: _authorDetailsKey,
+              child: AuthorDetailsScreen(
+                author: selectedAuthor,
+              ),
+            ),
+        ],
+      ],
+    );
+  }
+}

lib/13/go/raw_book/src/screens/scaffold.dart

@@ -0,0 +1,54 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:adaptive_navigation/adaptive_navigation.dart';
+import 'package:flutter/material.dart';
+
+import '../routing.dart';
+import 'scaffold_body.dart';
+
+class BookstoreScaffold extends StatelessWidget {
+  const BookstoreScaffold({
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final routeState = RouteStateScope.of(context);
+    final selectedIndex = _getSelectedIndex(routeState.route.pathTemplate);
+
+    return Scaffold(
+      body: AdaptiveNavigationScaffold(
+        selectedIndex: selectedIndex,
+        body: const BookstoreScaffoldBody(),
+        onDestinationSelected: (idx) {
+          if (idx == 0) routeState.go('/books/popular');
+          if (idx == 1) routeState.go('/authors');
+          if (idx == 2) routeState.go('/settings');
+        },
+        destinations: const [
+          AdaptiveScaffoldDestination(
+            title: 'Books',
+            icon: Icons.book,
+          ),
+          AdaptiveScaffoldDestination(
+            title: 'Authors',
+            icon: Icons.person,
+          ),
+          AdaptiveScaffoldDestination(
+            title: 'Settings',
+            icon: Icons.settings,
+          ),
+        ],
+      ),
+    );
+  }
+
+  int _getSelectedIndex(String pathTemplate) {
+    if (pathTemplate.startsWith('/books')) return 0;
+    if (pathTemplate == '/authors') return 1;
+    if (pathTemplate == '/settings') return 2;
+    return 0;
+  }
+}

lib/13/go/raw_book/src/screens/scaffold_body.dart

@@ -0,0 +1,63 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+import '../routing.dart';
+import '../screens/settings.dart';
+import '../widgets/fade_transition_page.dart';
+import 'authors.dart';
+import 'books.dart';
+import 'scaffold.dart';
+
+/// Displays the contents of the body of [BookstoreScaffold]
+class BookstoreScaffoldBody extends StatelessWidget {
+  static GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();
+
+  const BookstoreScaffoldBody({
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    var currentRoute = RouteStateScope.of(context).route;
+
+    // A nested Router isn't necessary because the back button behavior doesn't
+    // need to be customized.
+    return Navigator(
+      key: navigatorKey,
+      onPopPage: (route, dynamic result) => route.didPop(result),
+      pages: [
+        if (currentRoute.pathTemplate.startsWith('/authors'))
+          const FadeTransitionPage<void>(
+            key: ValueKey('authors'),
+            child: AuthorsScreen(),
+          )
+        else if (currentRoute.pathTemplate.startsWith('/settings'))
+          const FadeTransitionPage<void>(
+            key: ValueKey('settings'),
+            child: SettingsScreen(),
+          )
+        else if (currentRoute.pathTemplate.startsWith('/books') ||
+            currentRoute.pathTemplate == '/')
+          const FadeTransitionPage<void>(
+            key: ValueKey('books'),
+            child: BooksScreen(),
+          )
+
+        // Avoid building a Navigator with an empty `pages` list when the
+        // RouteState is set to an unexpected path, such as /signin.
+        //
+        // Since RouteStateScope is an InheritedNotifier, any change to the
+        // route will result in a call to this build method, even though this
+        // widget isn't built when those routes are active.
+        else
+          FadeTransitionPage<void>(
+            key: const ValueKey('empty'),
+            child: Container(),
+          ),
+      ],
+    );
+  }
+}

lib/13/go/raw_book/src/screens/settings.dart

@@ -0,0 +1,95 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:url_launcher/link.dart';
+
+import '../auth.dart';
+import '../routing.dart';
+
+class SettingsScreen extends StatefulWidget {
+  const SettingsScreen({super.key});
+
+  @override
+  State<SettingsScreen> createState() => _SettingsScreenState();
+}
+
+class _SettingsScreenState extends State<SettingsScreen> {
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        body: SafeArea(
+          child: SingleChildScrollView(
+            child: Align(
+              alignment: Alignment.topCenter,
+              child: ConstrainedBox(
+                constraints: const BoxConstraints(maxWidth: 400),
+                child: const Card(
+                  child: Padding(
+                    padding: EdgeInsets.symmetric(vertical: 18, horizontal: 12),
+                    child: SettingsContent(),
+                  ),
+                ),
+              ),
+            ),
+          ),
+        ),
+      );
+}
+
+class SettingsContent extends StatelessWidget {
+  const SettingsContent({
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) => Column(
+        children: [
+          ...[
+            Text(
+              'Settings',
+              style: Theme.of(context).textTheme.headlineMedium,
+            ),
+            FilledButton(
+              onPressed: () {
+                // BookstoreAuthScope.of(context).signOut();
+              },
+              child: const Text('Sign out'),
+            ),
+            Link(
+              uri: Uri.parse('/book/0'),
+              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)'),
+              onPressed: () {
+                RouteStateScope.of(context).go('/book/0');
+              },
+            ),
+          ].map((w) => Padding(padding: const EdgeInsets.all(8), child: w)),
+          TextButton(
+            onPressed: () => showDialog<String>(
+              context: context,
+              builder: (context) => AlertDialog(
+                title: const Text('Alert!'),
+                content: const Text('The alert description goes here.'),
+                actions: [
+                  TextButton(
+                    onPressed: () => Navigator.pop(context, 'Cancel'),
+                    child: const Text('Cancel'),
+                  ),
+                  TextButton(
+                    onPressed: () => Navigator.pop(context, 'OK'),
+                    child: const Text('OK'),
+                  ),
+                ],
+              ),
+            ),
+            child: const Text('Show Dialog'),
+          )
+        ],
+      );
+}

lib/13/go/raw_book/src/screens/sign_in.dart

@@ -0,0 +1,69 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+class Credentials {
+  final String username;
+  final String password;
+
+  Credentials(this.username, this.password);
+}
+
+class SignInScreen extends StatefulWidget {
+  final ValueChanged<Credentials> onSignIn;
+
+  const SignInScreen({
+    required this.onSignIn,
+    super.key,
+  });
+
+  @override
+  State<SignInScreen> createState() => _SignInScreenState();
+}
+
+class _SignInScreenState extends State<SignInScreen> {
+  final _usernameController = TextEditingController();
+  final _passwordController = TextEditingController();
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        body: Center(
+          child: Card(
+            child: Container(
+              constraints: BoxConstraints.loose(const Size(600, 600)),
+              padding: const EdgeInsets.all(8),
+              child: Column(
+                mainAxisAlignment: MainAxisAlignment.center,
+                mainAxisSize: MainAxisSize.min,
+                children: [
+                  Text('Sign in',
+                      style: Theme.of(context).textTheme.headlineMedium),
+                  TextField(
+                    decoration: const InputDecoration(labelText: 'Username'),
+                    controller: _usernameController,
+                  ),
+                  TextField(
+                    decoration: const InputDecoration(labelText: 'Password'),
+                    obscureText: true,
+                    controller: _passwordController,
+                  ),
+                  Padding(
+                    padding: const EdgeInsets.all(16),
+                    child: TextButton(
+                      onPressed: () async {
+                        widget.onSignIn(Credentials(
+                            _usernameController.value.text,
+                            _passwordController.value.text));
+                      },
+                      child: const Text('Sign in'),
+                    ),
+                  ),
+                ],
+              ),
+            ),
+          ),
+        ),
+      );
+}

lib/13/go/raw_book/src/widgets/author_list.dart

@@ -0,0 +1,32 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+import '../data.dart';
+
+class AuthorList extends StatelessWidget {
+  final List<Author> authors;
+  final ValueChanged<Author>? onTap;
+
+  const AuthorList({
+    required this.authors,
+    this.onTap,
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) => ListView.builder(
+        itemCount: authors.length,
+        itemBuilder: (context, index) => ListTile(
+          title: Text(
+            authors[index].name,
+          ),
+          subtitle: Text(
+            '${authors[index].books.length} books',
+          ),
+          onTap: onTap != null ? () => onTap!(authors[index]) : null,
+        ),
+      );
+}

lib/13/go/raw_book/src/widgets/book_list.dart

@@ -0,0 +1,32 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+import '../data.dart';
+
+class BookList extends StatelessWidget {
+  final List<Book> books;
+  final ValueChanged<Book>? onTap;
+
+  const BookList({
+    required this.books,
+    this.onTap,
+    super.key,
+  });
+
+  @override
+  Widget build(BuildContext context) => ListView.builder(
+        itemCount: books.length,
+        itemBuilder: (context, index) => ListTile(
+          title: Text(
+            books[index].title,
+          ),
+          subtitle: Text(
+            books[index].author.name,
+          ),
+          onTap: onTap != null ? () => onTap!(books[index]) : null,
+        ),
+      );
+}

lib/13/go/raw_book/src/widgets/fade_transition_page.dart

@@ -0,0 +1,53 @@
+// Copyright 2021, the Flutter project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+
+class FadeTransitionPage<T> extends Page<T> {
+  final Widget child;
+  final Duration duration;
+
+  const FadeTransitionPage({
+    super.key,
+    required this.child,
+    this.duration = const Duration(milliseconds: 300),
+  });
+
+  @override
+  Route<T> createRoute(BuildContext context) =>
+      PageBasedFadeTransitionRoute<T>(this);
+}
+
+class PageBasedFadeTransitionRoute<T> extends PageRoute<T> {
+  final FadeTransitionPage<T> _page;
+
+  PageBasedFadeTransitionRoute(this._page) : super(settings: _page);
+
+  @override
+  Color? get barrierColor => null;
+
+  @override
+  String? get barrierLabel => null;
+
+  @override
+  Duration get transitionDuration => _page.duration;
+
+  @override
+  bool get maintainState => true;
+
+  @override
+  Widget buildPage(BuildContext context, Animation<double> animation,
+      Animation<double> secondaryAnimation) {
+    var curveTween = CurveTween(curve: Curves.easeIn);
+    return FadeTransition(
+      opacity: animation.drive(curveTween),
+      child: (settings as FadeTransitionPage).child,
+    );
+  }
+
+  @override
+  Widget buildTransitions(BuildContext context, Animation<double> animation,
+          Animation<double> secondaryAnimation, Widget child) =>
+      child;
+}

lib/13/go/redirection.dart

@@ -0,0 +1,146 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:provider/provider.dart';
+
+// This scenario demonstrates how to use redirect to handle a sign-in flow.
+//
+// The GoRouter.redirect method is called before the app is navigate to a
+// new page. You can choose to redirect to a different page by returning a
+// non-null URL string.
+
+/// The login information.
+class LoginInfo extends ChangeNotifier {
+  /// The username of login.
+  String get userName => _userName;
+  String _userName = '';
+
+  /// Whether a user has logged in.
+  bool get loggedIn => _userName.isNotEmpty;
+
+  /// Logs in a user.
+  void login(String userName) {
+    _userName = userName;
+    notifyListeners();
+  }
+
+  /// Logs out the current user.
+  void logout() {
+    _userName = '';
+    notifyListeners();
+  }
+}
+
+void main() => runApp(App());
+
+/// The main app.
+class App extends StatelessWidget {
+  /// Creates an [App].
+  App({super.key});
+
+  final LoginInfo _loginInfo = LoginInfo();
+
+  /// The title of the app.
+  static const String title = 'GoRouter Example: Redirection';
+
+  // add the login info into the tree as app state that can change over time
+  @override
+  Widget build(BuildContext context) => ChangeNotifierProvider<LoginInfo>.value(
+        value: _loginInfo,
+        child: MaterialApp.router(
+          routerConfig: _router,
+          title: title,
+          debugShowCheckedModeBanner: false,
+        ),
+      );
+
+  late final GoRouter _router = GoRouter(
+    routes: <GoRoute>[
+      GoRoute(
+        path: '/',
+        builder: (BuildContext context, GoRouterState state) =>
+            const HomeScreen(),
+      ),
+      GoRoute(
+        path: '/login',
+        builder: (BuildContext context, GoRouterState state) =>
+            const LoginScreen(),
+      ),
+    ],
+
+    // redirect to the login page if the user is not logged in
+    redirect: (BuildContext context, GoRouterState state) {
+      // if the user is not logged in, they need to login
+      final bool loggedIn = _loginInfo.loggedIn;
+      final bool loggingIn = state.matchedLocation == '/login';
+      if (!loggedIn) {
+        return '/login';
+      }
+
+      // if the user is logged in but still on the login page, send them to
+      // the home page
+      if (loggingIn) {
+        return '/';
+      }
+
+      // no need to redirect at all
+      return null;
+    },
+
+    // changes on the listenable will cause the router to refresh it's route
+    refreshListenable: _loginInfo,
+  );
+}
+
+/// The login screen.
+class LoginScreen extends StatelessWidget {
+  /// Creates a [LoginScreen].
+  const LoginScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) => Scaffold(
+        appBar: AppBar(title: const Text(App.title)),
+        body: Center(
+          child: ElevatedButton(
+            onPressed: () {
+              // log a user in, letting all the listeners know
+              context.read<LoginInfo>().login('test-user');
+
+              // router will automatically redirect from /login to / using
+              // refreshListenable
+            },
+            child: const Text('Login'),
+          ),
+        ),
+      );
+}
+
+/// The home screen.
+class HomeScreen extends StatelessWidget {
+  /// Creates a [HomeScreen].
+  const HomeScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final LoginInfo info = context.read<LoginInfo>();
+
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text(App.title),
+        actions: <Widget>[
+          IconButton(
+            onPressed: info.logout,
+            tooltip: 'Logout: ${info.userName}',
+            icon: const Icon(Icons.logout),
+          )
+        ],
+      ),
+      body: const Center(
+        child: Text('HomeScreen'),
+      ),
+    );
+  }
+}

lib/13/go/shell_route.dart

@@ -0,0 +1,289 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+final GlobalKey<NavigatorState> _rootNavigatorKey =
+    GlobalKey<NavigatorState>(debugLabel: 'root');
+final GlobalKey<NavigatorState> _shellNavigatorKey =
+    GlobalKey<NavigatorState>(debugLabel: 'shell');
+
+// This scenario demonstrates how to set up nested navigation using ShellRoute,
+// which is a pattern where an additional Navigator is placed in the widget tree
+// to be used instead of the root navigator. This allows deep-links to display
+// pages along with other UI components such as a BottomNavigationBar.
+//
+// This example demonstrates how to display a route within a ShellRoute and also
+// push a screen using a different navigator (such as the root Navigator) by
+// providing a `parentNavigatorKey`.
+
+void main() {
+  runApp(ShellRouteExampleApp());
+}
+
+/// An example demonstrating how to use [ShellRoute]
+class ShellRouteExampleApp extends StatelessWidget {
+  /// Creates a [ShellRouteExampleApp]
+  ShellRouteExampleApp({super.key});
+
+  final GoRouter _router = GoRouter(
+    navigatorKey: _rootNavigatorKey,
+    initialLocation: '/a',
+    debugLogDiagnostics: true,
+    routes: <RouteBase>[
+      /// Application shell
+      ShellRoute(
+        navigatorKey: _shellNavigatorKey,
+        builder: (BuildContext context, GoRouterState state, Widget child) {
+          return ScaffoldWithNavBar(child: child);
+        },
+        routes: <RouteBase>[
+          /// The first screen to display in the bottom navigation bar.
+          GoRoute(
+            path: '/a',
+            builder: (BuildContext context, GoRouterState state) {
+              return const ScreenA();
+            },
+            routes: <RouteBase>[
+              // The details screen to display stacked on the inner Navigator.
+              // This will cover screen A but not the application shell.
+              GoRoute(
+                path: 'details',
+                builder: (BuildContext context, GoRouterState state) {
+                  return const DetailsScreen(label: 'A');
+                },
+              ),
+            ],
+          ),
+
+          /// Displayed when the second item in the the bottom navigation bar is
+          /// selected.
+          GoRoute(
+            path: '/b',
+            builder: (BuildContext context, GoRouterState state) {
+              return const ScreenB();
+            },
+            routes: <RouteBase>[
+              /// Same as "/a/details", but displayed on the root Navigator by
+              /// specifying [parentNavigatorKey]. This will cover both screen B
+              /// and the application shell.
+              GoRoute(
+                path: 'details',
+                parentNavigatorKey: _rootNavigatorKey,
+                builder: (BuildContext context, GoRouterState state) {
+                  return const DetailsScreen(label: 'B');
+                },
+              ),
+            ],
+          ),
+
+          /// The third screen to display in the bottom navigation bar.
+          GoRoute(
+            path: '/c',
+            builder: (BuildContext context, GoRouterState state) {
+              return const ScreenC();
+            },
+            routes: <RouteBase>[
+              // The details screen to display stacked on the inner Navigator.
+              // This will cover screen A but not the application shell.
+              GoRoute(
+                path: 'details',
+                builder: (BuildContext context, GoRouterState state) {
+                  return const DetailsScreen(label: 'C');
+                },
+              ),
+            ],
+          ),
+        ],
+      ),
+    ],
+  );
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp.router(
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      routerConfig: _router,
+    );
+  }
+}
+
+/// Builds the "shell" for the app by building a Scaffold with a
+/// BottomNavigationBar, where [child] is placed in the body of the Scaffold.
+class ScaffoldWithNavBar extends StatelessWidget {
+  /// Constructs an [ScaffoldWithNavBar].
+  const ScaffoldWithNavBar({
+    required this.child,
+    super.key,
+  });
+
+  /// The widget to display in the body of the Scaffold.
+  /// In this sample, it is a Navigator.
+  final Widget child;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: child,
+      bottomNavigationBar: BottomNavigationBar(
+        items: const <BottomNavigationBarItem>[
+          BottomNavigationBarItem(
+            icon: Icon(Icons.home),
+            label: 'A Screen',
+          ),
+          BottomNavigationBarItem(
+            icon: Icon(Icons.business),
+            label: 'B Screen',
+          ),
+          BottomNavigationBarItem(
+            icon: Icon(Icons.notification_important_rounded),
+            label: 'C Screen',
+          ),
+        ],
+        currentIndex: _calculateSelectedIndex(context),
+        onTap: (int idx) => _onItemTapped(idx, context),
+      ),
+    );
+  }
+
+  static int _calculateSelectedIndex(BuildContext context) {
+    final String location = GoRouterState.of(context).uri.toString();
+    if (location.startsWith('/a')) {
+      return 0;
+    }
+    if (location.startsWith('/b')) {
+      return 1;
+    }
+    if (location.startsWith('/c')) {
+      return 2;
+    }
+    return 0;
+  }
+
+  void _onItemTapped(int index, BuildContext context) {
+    switch (index) {
+      case 0:
+        GoRouter.of(context).go('/a');
+        break;
+      case 1:
+        GoRouter.of(context).go('/b');
+        break;
+      case 2:
+        GoRouter.of(context).go('/c');
+        break;
+    }
+  }
+}
+
+/// The first screen in the bottom navigation bar.
+class ScreenA extends StatelessWidget {
+  /// Constructs a [ScreenA] widget.
+  const ScreenA({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(),
+      body: Center(
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: <Widget>[
+            const Text('Screen A'),
+            TextButton(
+              onPressed: () {
+                GoRouter.of(context).go('/a/details');
+              },
+              child: const Text('View A details'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+/// The second screen in the bottom navigation bar.
+class ScreenB extends StatelessWidget {
+  /// Constructs a [ScreenB] widget.
+  const ScreenB({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(),
+      body: Center(
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: <Widget>[
+            const Text('Screen B'),
+            TextButton(
+              onPressed: () {
+                GoRouter.of(context).go('/b/details');
+              },
+              child: const Text('View B details'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+/// The third screen in the bottom navigation bar.
+class ScreenC extends StatelessWidget {
+  /// Constructs a [ScreenC] widget.
+  const ScreenC({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(),
+      body: Center(
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: <Widget>[
+            const Text('Screen C'),
+            TextButton(
+              onPressed: () {
+                GoRouter.of(context).go('/c/details');
+              },
+              child: const Text('View C details'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+/// The details screen for either the A, B or C screen.
+class DetailsScreen extends StatelessWidget {
+  /// Constructs a [DetailsScreen].
+  const DetailsScreen({
+    required this.label,
+    super.key,
+  });
+
+  /// The label to display in the center of the screen.
+  final String label;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text('Details Screen'),
+      ),
+      body: Center(
+        child: Text(
+          'Details for $label',
+          style: Theme.of(context).textTheme.headlineMedium,
+        ),
+      ),
+    );
+  }
+}

lib/13/go/stateful_shell_route.dart

@@ -0,0 +1,324 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+final GlobalKey<NavigatorState> _rootNavigatorKey =
+    GlobalKey<NavigatorState>(debugLabel: 'root');
+final GlobalKey<NavigatorState> _sectionANavigatorKey =
+    GlobalKey<NavigatorState>(debugLabel: 'sectionANav');
+
+// This example demonstrates how to setup nested navigation using a
+// BottomNavigationBar, where each bar item uses its own persistent navigator,
+// i.e. navigation state is maintained separately for each item. This setup also
+// enables deep linking into nested pages.
+
+void main() {
+  runApp(NestedTabNavigationExampleApp());
+}
+
+/// An example demonstrating how to use nested navigators
+class NestedTabNavigationExampleApp extends StatelessWidget {
+  /// Creates a NestedTabNavigationExampleApp
+  NestedTabNavigationExampleApp({super.key});
+
+  final GoRouter _router = GoRouter(
+    navigatorKey: _rootNavigatorKey,
+    initialLocation: '/a',
+    routes: <RouteBase>[
+      StatefulShellRoute.indexedStack(
+        builder: (BuildContext context, GoRouterState state,
+            StatefulNavigationShell navigationShell) {
+          // Return the widget that implements the custom shell (in this case
+          // using a BottomNavigationBar). The StatefulNavigationShell is passed
+          // to be able access the state of the shell and to navigate to other
+          // branches in a stateful way.
+          return ScaffoldWithNavBar(navigationShell: navigationShell);
+        },
+        branches: <StatefulShellBranch>[
+          // The route branch for the first tab of the bottom navigation bar.
+          StatefulShellBranch(
+            navigatorKey: _sectionANavigatorKey,
+            routes: <RouteBase>[
+              GoRoute(
+                // The screen to display as the root in the first tab of the
+                // bottom navigation bar.
+                path: '/a',
+                builder: (BuildContext context, GoRouterState state) =>
+                    const RootScreen(label: 'A', detailsPath: '/a/details'),
+                routes: <RouteBase>[
+                  // The details screen to display stacked on navigator of the
+                  // first tab. This will cover screen A but not the application
+                  // shell (bottom navigation bar).
+                  GoRoute(
+                    path: 'details',
+                    builder: (BuildContext context, GoRouterState state) =>
+                        const DetailsScreen(label: 'A'),
+                  ),
+                ],
+              ),
+            ],
+          ),
+
+          // The route branch for the second tab of the bottom navigation bar.
+          StatefulShellBranch(
+            // It's not necessary to provide a navigatorKey if it isn't also
+            // needed elsewhere. If not provided, a default key will be used.
+            routes: <RouteBase>[
+              GoRoute(
+                // The screen to display as the root in the second tab of the
+                // bottom navigation bar.
+                path: '/b',
+                builder: (BuildContext context, GoRouterState state) =>
+                    const RootScreen(
+                  label: 'B',
+                  detailsPath: '/b/details/1',
+                  secondDetailsPath: '/b/details/2',
+                ),
+                routes: <RouteBase>[
+                  GoRoute(
+                    path: 'details/:param',
+                    builder: (BuildContext context, GoRouterState state) =>
+                        DetailsScreen(
+                      label: 'B',
+                      param: state.pathParameters['param'],
+                    ),
+                  ),
+                ],
+              ),
+            ],
+          ),
+
+          // The route branch for the third tab of the bottom navigation bar.
+          StatefulShellBranch(
+            routes: <RouteBase>[
+              GoRoute(
+                // The screen to display as the root in the third tab of the
+                // bottom navigation bar.
+                path: '/c',
+                builder: (BuildContext context, GoRouterState state) =>
+                    const RootScreen(
+                  label: 'C',
+                  detailsPath: '/c/details',
+                ),
+                routes: <RouteBase>[
+                  GoRoute(
+                    path: 'details',
+                    builder: (BuildContext context, GoRouterState state) =>
+                        DetailsScreen(
+                      label: 'C',
+                      extra: state.extra,
+                    ),
+                  ),
+                ],
+              ),
+            ],
+          ),
+        ],
+      ),
+    ],
+  );
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp.router(
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+      ),
+      routerConfig: _router,
+    );
+  }
+}
+
+/// Builds the "shell" for the app by building a Scaffold with a
+/// BottomNavigationBar, where [child] is placed in the body of the Scaffold.
+class ScaffoldWithNavBar extends StatelessWidget {
+  /// Constructs an [ScaffoldWithNavBar].
+  const ScaffoldWithNavBar({
+    required this.navigationShell,
+    Key? key,
+  }) : super(key: key ?? const ValueKey<String>('ScaffoldWithNavBar'));
+
+  /// The navigation shell and container for the branch Navigators.
+  final StatefulNavigationShell navigationShell;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: navigationShell,
+      bottomNavigationBar: BottomNavigationBar(
+        // Here, the items of BottomNavigationBar are hard coded. In a real
+        // world scenario, the items would most likely be generated from the
+        // branches of the shell route, which can be fetched using
+        // `navigationShell.route.branches`.
+        items: const <BottomNavigationBarItem>[
+          BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Section A'),
+          BottomNavigationBarItem(icon: Icon(Icons.work), label: 'Section B'),
+          BottomNavigationBarItem(icon: Icon(Icons.tab), label: 'Section C'),
+        ],
+        currentIndex: navigationShell.currentIndex,
+        onTap: (int index) => _onTap(context, index),
+      ),
+    );
+  }
+
+  /// Navigate to the current location of the branch at the provided index when
+  /// tapping an item in the BottomNavigationBar.
+  void _onTap(BuildContext context, int index) {
+    // When navigating to a new branch, it's recommended to use the goBranch
+    // method, as doing so makes sure the last navigation state of the
+    // Navigator for the branch is restored.
+    navigationShell.goBranch(
+      index,
+      // A common pattern when using bottom navigation bars is to support
+      // navigating to the initial location when tapping the item that is
+      // already active. This example demonstrates how to support this behavior,
+      // using the initialLocation parameter of goBranch.
+      initialLocation: index == navigationShell.currentIndex,
+    );
+  }
+}
+
+/// Widget for the root/initial pages in the bottom navigation bar.
+class RootScreen extends StatelessWidget {
+  /// Creates a RootScreen
+  const RootScreen({
+    required this.label,
+    required this.detailsPath,
+    this.secondDetailsPath,
+    super.key,
+  });
+
+  /// The label
+  final String label;
+
+  /// The path to the detail page
+  final String detailsPath;
+
+  /// The path to another detail page
+  final String? secondDetailsPath;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('Root of section $label'),
+      ),
+      body: Center(
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: <Widget>[
+            Text('Screen $label',
+                style: Theme.of(context).textTheme.titleLarge),
+            const Padding(padding: EdgeInsets.all(4)),
+            TextButton(
+              onPressed: () {
+                GoRouter.of(context).go(detailsPath, extra: '$label-XYZ');
+              },
+              child: const Text('View details'),
+            ),
+            const Padding(padding: EdgeInsets.all(4)),
+            if (secondDetailsPath != null)
+              TextButton(
+                onPressed: () {
+                  GoRouter.of(context).go(secondDetailsPath!);
+                },
+                child: const Text('View more details'),
+              ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+/// The details screen for either the A or B screen.
+class DetailsScreen extends StatefulWidget {
+  /// Constructs a [DetailsScreen].
+  const DetailsScreen({
+    required this.label,
+    this.param,
+    this.extra,
+    this.withScaffold = true,
+    super.key,
+  });
+
+  /// The label to display in the center of the screen.
+  final String label;
+
+  /// Optional param
+  final String? param;
+
+  /// Optional extra object
+  final Object? extra;
+
+  /// Wrap in scaffold
+  final bool withScaffold;
+
+  @override
+  State<StatefulWidget> createState() => DetailsScreenState();
+}
+
+/// The state for DetailsScreen
+class DetailsScreenState extends State<DetailsScreen> {
+  int _counter = 0;
+
+  @override
+  Widget build(BuildContext context) {
+    if (widget.withScaffold) {
+      return Scaffold(
+        appBar: AppBar(
+          title: Text('Details Screen - ${widget.label}'),
+        ),
+        body: _build(context),
+      );
+    } else {
+      return Container(
+        color: Theme.of(context).scaffoldBackgroundColor,
+        child: _build(context),
+      );
+    }
+  }
+
+  Widget _build(BuildContext context) {
+    return Center(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: <Widget>[
+          Text('Details for ${widget.label} - Counter: $_counter',
+              style: Theme.of(context).textTheme.titleLarge),
+          const Padding(padding: EdgeInsets.all(4)),
+          TextButton(
+            onPressed: () {
+              setState(() {
+                _counter++;
+              });
+            },
+            child: const Text('Increment counter'),
+          ),
+          const Padding(padding: EdgeInsets.all(8)),
+          if (widget.param != null)
+            Text('Parameter: ${widget.param!}',
+                style: Theme.of(context).textTheme.titleMedium),
+          const Padding(padding: EdgeInsets.all(8)),
+          if (widget.extra != null)
+            Text('Extra: ${widget.extra!}',
+                style: Theme.of(context).textTheme.titleMedium),
+          if (!widget.withScaffold) ...<Widget>[
+            const Padding(padding: EdgeInsets.all(16)),
+            TextButton(
+              onPressed: () {
+                GoRouter.of(context).pop();
+              },
+              child: const Text('< Back',
+                  style: TextStyle(fontWeight: FontWeight.bold, fontSize: 18)),
+            ),
+          ]
+        ],
+      ),
+    );
+  }
+}

lib/13/go/transition_animations.dart

@@ -0,0 +1,175 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+/// To use a custom transition animation, provide a `pageBuilder` with a
+/// CustomTransitionPage.
+///
+/// To learn more about animation in Flutter, check out the [Introduction to
+/// animations](https://docs.flutter.dev/development/ui/animations) page on
+/// flutter.dev.
+void main() => runApp(const MyApp());
+
+/// The route configuration.
+final GoRouter _router = GoRouter(
+  routes: <RouteBase>[
+    GoRoute(
+      path: '/',
+      builder: (BuildContext context, GoRouterState state) {
+        return const HomeScreen();
+      },
+      routes: <RouteBase>[
+        GoRoute(
+          path: 'details',
+          pageBuilder: (BuildContext context, GoRouterState state) {
+            return CustomTransitionPage<void>(
+              key: state.pageKey,
+              child: const DetailsScreen(),
+              transitionDuration: const Duration(milliseconds: 150),
+              transitionsBuilder: (BuildContext context,
+                  Animation<double> animation,
+                  Animation<double> secondaryAnimation,
+                  Widget child) {
+                // Change the opacity of the screen using a Curve based on the the animation's
+                // value
+                return FadeTransition(
+                  opacity:
+                      CurveTween(curve: Curves.easeInOut).animate(animation),
+                  child: child,
+                );
+              },
+            );
+          },
+        ),
+        GoRoute(
+          path: 'dismissible-details',
+          pageBuilder: (BuildContext context, GoRouterState state) {
+            return CustomTransitionPage<void>(
+              key: state.pageKey,
+              child: const DismissibleDetails(),
+              barrierDismissible: true,
+              barrierColor: Colors.black38,
+              opaque: false,
+              transitionDuration: Duration.zero,
+              transitionsBuilder: (_, __, ___, Widget child) => child,
+            );
+          },
+        ),
+        GoRoute(
+          path: 'custom-reverse-transition-duration',
+          pageBuilder: (BuildContext context, GoRouterState state) {
+            return CustomTransitionPage<void>(
+              key: state.pageKey,
+              child: const DetailsScreen(),
+              barrierDismissible: true,
+              barrierColor: Colors.black38,
+              opaque: false,
+              transitionDuration: const Duration(milliseconds: 500),
+              reverseTransitionDuration: const Duration(milliseconds: 200),
+              transitionsBuilder: (BuildContext context,
+                  Animation<double> animation,
+                  Animation<double> secondaryAnimation,
+                  Widget child) {
+                return FadeTransition(
+                  opacity: animation,
+                  child: child,
+                );
+              },
+            );
+          },
+        ),
+      ],
+    ),
+  ],
+);
+
+/// The main app.
+class MyApp extends StatelessWidget {
+  /// Constructs a [MyApp]
+  const MyApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp.router(
+      routerConfig: _router,
+    );
+  }
+}
+
+/// The home screen
+class HomeScreen extends StatelessWidget {
+  /// Constructs a [HomeScreen]
+  const HomeScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Home Screen')),
+      body: Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: <Widget>[
+            ElevatedButton(
+              onPressed: () => context.go('/details'),
+              child: const Text('Go to the Details screen'),
+            ),
+            const SizedBox(height: 48),
+            ElevatedButton(
+              onPressed: () => context.go('/dismissible-details'),
+              child: const Text('Go to the Dismissible Details screen'),
+            ),
+            const SizedBox(height: 48),
+            ElevatedButton(
+              onPressed: () =>
+                  context.go('/custom-reverse-transition-duration'),
+              child: const Text(
+                'Go to the Custom Reverse Transition Duration Screen',
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+/// The details screen
+class DetailsScreen extends StatelessWidget {
+  /// Constructs a [DetailsScreen]
+  const DetailsScreen({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('Details Screen')),
+      body: Center(
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: <Widget>[
+            ElevatedButton(
+              onPressed: () => context.go('/'),
+              child: const Text('Go back to the Home screen'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+/// The dismissible details screen
+class DismissibleDetails extends StatelessWidget {
+  /// Constructs a [DismissibleDetails]
+  const DismissibleDetails({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return const Padding(
+      padding: EdgeInsets.all(48),
+      child: ColoredBox(color: Colors.red),
+    );
+  }
+}