Replace navigation_and_routing with a new sample (#832)

* move snippets into old_snippets directory

* add new navigation_and_routing sample

* add copyright headers

* Apply #827 to old_snippets/ directory and upgrade them to null safety

* Code review comments

- Move Guard class into parser.dart
- Move usage of guards from Delegate to RouteInformationParser
- Rename delegate to SimpleRouterDelegate

* clean up imports

* refactor settings screen, fix bug

* avoid conflicting paths /books/new and /books/1 - rename to book/1

* dispose fields in _BookstoreState class

* remove /books path

This was causing problems

* add comment

* Change BookstoreAuthScope and BookstoreAuthScope to InheritedNotifier

* fix warnings

* Make the initial route configurable, set to '/signin'

* Enable deep linking

https://flutter.dev/docs/development/ui/navigation/deep-linking

* use path URL strategy on the web.

* remove TODO, add comment

navigation_and_routing/lib/src/routing/delegate.dart

@@ -0,0 +1,52 @@
+// 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 'parsed_route.dart';
+import 'route_state.dart';
+
+class SimpleRouterDelegate extends RouterDelegate<ParsedRoute>
+    with ChangeNotifier, PopNavigatorRouterDelegateMixin<ParsedRoute> {
+  final RouteState routeState;
+  final WidgetBuilder builder;
+
+  @override
+  final GlobalKey<NavigatorState> navigatorKey;
+
+  SimpleRouterDelegate({
+    required this.routeState,
+    required this.builder,
+    required this.navigatorKey,
+    // ignore: prefer_initializing_formals
+  }) {
+    routeState.addListener(notifyListeners);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return builder(context);
+  }
+
+  @override
+  Future<void> setNewRoutePath(ParsedRoute configuration) async {
+    routeState.route = configuration;
+    return SynchronousFuture(null);
+  }
+
+  @override
+  ParsedRoute get currentConfiguration {
+    return routeState.route;
+  }
+
+  @override
+  void dispose() {
+    routeState.removeListener(notifyListeners);
+    routeState.dispose();
+    super.dispose();
+  }
+}

navigation_and_routing/lib/src/routing/parsed_route.dart

@@ -0,0 +1,45 @@
+// 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 {
+  final String path;
+  final String pathTemplate;
+  final Map<String, String> parameters;
+  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) {
+    return 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>';
+}

navigation_and_routing/lib/src/routing/parser.dart

@@ -0,0 +1,68 @@
+// 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';
+
+abstract class RouteGuard<T> {
+  Future<T> redirect(T from);
+}
+
+/// Parses the URI path into a [ParsedRoute].
+class TemplateRouteParser extends RouteInformationParser<ParsedRoute> {
+  final List<String> _pathTemplates = [];
+  RouteGuard<ParsedRoute>? guard;
+  final ParsedRoute initialRoute;
+
+  TemplateRouteParser(List<String> pathTemplates,
+      {String? initialRoute = '/', this.guard})
+      : initialRoute =
+            ParsedRoute(initialRoute ?? '/', initialRoute ?? '/', {}, {}) {
+    for (var template in pathTemplates) {
+      _addRoute(template);
+    }
+  }
+
+  void _addRoute(String pathTemplate) {
+    _pathTemplates.add(pathTemplate);
+  }
+
+  @override
+  Future<ParsedRoute> parseRouteInformation(
+      RouteInformation routeInformation) async {
+    return await _parse(routeInformation);
+  }
+
+  Future<ParsedRoute> _parse(RouteInformation routeInformation) async {
+    final path = routeInformation.location!;
+    final queryParams = Uri.parse(path).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);
+      }
+    }
+
+    // Redirect if a guard is present
+    var guard = this.guard;
+    if (guard != null) {
+      return guard.redirect(parsedRoute);
+    }
+
+    return parsedRoute;
+  }
+
+  @override
+  RouteInformation restoreRouteInformation(ParsedRoute configuration) {
+    return RouteInformation(location: configuration.path);
+  }
+}

navigation_and_routing/lib/src/routing/route_state.dart

@@ -0,0 +1,50 @@
+// 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/foundation.dart';
+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
+/// `RouteState.of(context)` and call `go()`:
+///
+/// ```
+/// RouteState.of(context).go('/book/2');
+/// ```
+class RouteState extends ChangeNotifier {
+  TemplateRouteParser parser;
+  ParsedRoute _route;
+
+  RouteState(this.parser)
+      : _route = parser.initialRoute;
+
+  ParsedRoute get route => _route;
+
+  set route(ParsedRoute route) {
+    _route = route;
+    notifyListeners();
+  }
+
+  Future<void> go(String route) async {
+    this.route =
+        await parser.parseRouteInformation(RouteInformation(location: route));
+  }
+}
+
+/// Provides the current [RouteState] to descendent widgets in the tree.
+class RouteStateScope extends InheritedNotifier<RouteState> {
+  const RouteStateScope({
+    required RouteState notifier,
+    required Widget child,
+    Key? key,
+  }) : super(key: key, notifier: notifier, child: child);
+
+  static RouteState? of(BuildContext context) {
+    return context
+        .dependOnInheritedWidgetOfExactType<RouteStateScope>()
+        ?.notifier;
+  }
+}