packages/go_router/lib/src/builder.dart - mirrors/packages - Git at Google

 // 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/widgets.dart';

 import '../go_router.dart';
 import 'configuration.dart';
 import 'logging.dart';
 import 'match.dart';
 import 'misc/error_screen.dart';
 import 'misc/errors.dart';
 import 'pages/cupertino.dart';
 import 'pages/material.dart';
 import 'route_data.dart';
 import 'typedefs.dart';

 /// Signature for a function that takes in a `route` to be popped with
 /// the `result` and returns a boolean decision on whether the pop
 /// is successful.
 ///
 /// The `match` is the corresponding [RouteMatch] the `route`
 /// associates with.
 ///
 /// Used by of [RouteBuilder.onPopPageWithRouteMatch].
 typedef PopPageWithRouteMatchCallback = bool Function(
     Route<dynamic> route, dynamic result, RouteMatch? match);

 /// Builds the top-level Navigator for GoRouter.
 class RouteBuilder {
   /// [RouteBuilder] constructor.
   RouteBuilder({
     required this.configuration,
     required this.builderWithNav,
     required this.errorPageBuilder,
     required this.errorBuilder,
     required this.restorationScopeId,
     required this.observers,
     required this.onPopPageWithRouteMatch,
   });

   /// Builder function for a go router with Navigator.
   final GoRouterBuilderWithNav builderWithNav;

   /// Error page builder for the go router delegate.
   final GoRouterPageBuilder? errorPageBuilder;

   /// Error widget builder for the go router delegate.
   final GoRouterWidgetBuilder? errorBuilder;

   /// The route configuration for the app.
   final RouteConfiguration configuration;

   /// Restoration ID to save and restore the state of the navigator, including
   /// its history.
   final String? restorationScopeId;

   /// NavigatorObserver used to receive notifications when navigating in between routes.
   /// changes.
   final List<NavigatorObserver> observers;

   final GoRouterStateRegistry _registry = GoRouterStateRegistry();

   /// A callback called when a `route` produced by `match` is about to be popped
   /// with the `result`.
   ///
   /// If this method returns true, this builder pops the `route` and `match`.
   ///
   /// If this method returns false, this builder aborts the pop.
   final PopPageWithRouteMatchCallback onPopPageWithRouteMatch;

   /// Caches a HeroController for the nested Navigator, which solves cases where the
   /// Hero Widget animation stops working when navigating.
   // TODO(chunhtai): Remove _goHeroCache once below issue is fixed:
   // https://github.com/flutter/flutter/issues/54200
   final Map<GlobalKey<NavigatorState>, HeroController> _goHeroCache =
       <GlobalKey<NavigatorState>, HeroController>{};

   /// Builds the top-level Navigator for the given [RouteMatchList].
   Widget build(
     BuildContext context,
     RouteMatchList matchList,
     bool routerNeglect,
   ) {
     if (matchList.isEmpty && !matchList.isError) {
       // The build method can be called before async redirect finishes. Build a
       // empty box until then.
       return const SizedBox.shrink();
     }
     return builderWithNav(
       context,
       Builder(
         builder: (BuildContext context) {
           final Map<Page<Object?>, GoRouterState> newRegistry =
               <Page<Object?>, GoRouterState>{};
           final Widget result = tryBuild(context, matchList, routerNeglect,
               configuration.navigatorKey, newRegistry);
           _registry.updateRegistry(newRegistry);
           return GoRouterStateRegistryScope(registry: _registry, child: result);
         },
       ),
     );
   }

   /// Builds the top-level Navigator by invoking the build method on each
   /// matching route.
   ///
   /// Throws a [_RouteBuilderError].
   @visibleForTesting
   Widget tryBuild(
     BuildContext context,
     RouteMatchList matchList,
     bool routerNeglect,
     GlobalKey<NavigatorState> navigatorKey,
     Map<Page<Object?>, GoRouterState> registry,
   ) {
     // TODO(chunhtai): move the state from local scope to a central place.
     // https://github.com/flutter/flutter/issues/126365
     final _PagePopContext pagePopContext =
         _PagePopContext._(onPopPageWithRouteMatch);
     return builderWithNav(
       context,
       _buildNavigator(
         pagePopContext.onPopPage,
         _buildPages(context, matchList, pagePopContext, routerNeglect,
             navigatorKey, registry),
         navigatorKey,
         observers: observers,
         restorationScopeId: restorationScopeId,
       ),
     );
   }

   /// Returns the top-level pages instead of the root navigator. Used for
   /// testing.
   List<Page<Object?>> _buildPages(
       BuildContext context,
       RouteMatchList matchList,
       _PagePopContext pagePopContext,
       bool routerNeglect,
       GlobalKey<NavigatorState> navigatorKey,
       Map<Page<Object?>, GoRouterState> registry) {
     final Map<GlobalKey<NavigatorState>, List<Page<Object?>>> keyToPage;
     if (matchList.isError) {
       keyToPage = <GlobalKey<NavigatorState>, List<Page<Object?>>>{
         navigatorKey: <Page<Object?>>[
           _buildErrorPage(context, _buildErrorState(matchList)),
         ]
       };
     } else {
       keyToPage = <GlobalKey<NavigatorState>, List<Page<Object?>>>{};
       _buildRecursive(context, matchList, 0, pagePopContext, routerNeglect,
           keyToPage, navigatorKey, registry);

       // Every Page should have a corresponding RouteMatch.
       assert(keyToPage.values.flattened.every((Page<Object?> page) =>
           pagePopContext.getRouteMatchForPage(page) != null));
     }

     /// Clean up previous cache to prevent memory leak, making sure any nested
     /// stateful shell routes for the current match list are kept.
     final Set<Key> activeKeys = keyToPage.keys.toSet()
       ..addAll(_nestedStatefulNavigatorKeys(matchList));
     _goHeroCache.removeWhere(
         (GlobalKey<NavigatorState> key, _) => !activeKeys.contains(key));
     return keyToPage[navigatorKey]!;
   }

   static Set<GlobalKey<NavigatorState>> _nestedStatefulNavigatorKeys(
       RouteMatchList matchList) {
     final StatefulShellRoute? shellRoute =
         matchList.routes.whereType<StatefulShellRoute>().firstOrNull;
     if (shellRoute == null) {
       return <GlobalKey<NavigatorState>>{};
     }
     return RouteBase.routesRecursively(<RouteBase>[shellRoute])
         .whereType<StatefulShellRoute>()
         .expand((StatefulShellRoute e) =>
             e.branches.map((StatefulShellBranch b) => b.navigatorKey))
         .toSet();
   }

   void _buildRecursive(
     BuildContext context,
     RouteMatchList matchList,
     int startIndex,
     _PagePopContext pagePopContext,
     bool routerNeglect,
     Map<GlobalKey<NavigatorState>, List<Page<Object?>>> keyToPages,
     GlobalKey<NavigatorState> navigatorKey,
     Map<Page<Object?>, GoRouterState> registry,
   ) {
     if (startIndex >= matchList.matches.length) {
       return;
     }
     final RouteMatch match = matchList.matches[startIndex];

     final RouteBase route = match.route;
     final GoRouterState state = buildState(matchList, match);
     Page<Object?>? page;
     if (state.error != null) {
       page = _buildErrorPage(context, state);
       keyToPages.putIfAbsent(navigatorKey, () => <Page<Object?>>[]).add(page);
       _buildRecursive(context, matchList, startIndex + 1, pagePopContext,
           routerNeglect, keyToPages, navigatorKey, registry);
     } else {
       // If this RouteBase is for a different Navigator, add it to the
       // list of out of scope pages
       final GlobalKey<NavigatorState> routeNavKey =
           route.parentNavigatorKey ?? navigatorKey;
       if (route is GoRoute) {
         page =
             _buildPageForGoRoute(context, state, match, route, pagePopContext);

         keyToPages.putIfAbsent(routeNavKey, () => <Page<Object?>>[]).add(page);

         _buildRecursive(context, matchList, startIndex + 1, pagePopContext,
             routerNeglect, keyToPages, navigatorKey, registry);
       } else if (route is ShellRouteBase) {
         assert(startIndex + 1 < matchList.matches.length,
             'Shell routes must always have child routes');

         // Add an entry for the parent navigator if none exists.
         //
         // Calling _buildRecursive can result in adding pages to the
         // parentNavigatorKey entry's list. Store the current length so
         // that the page for this ShellRoute is placed at the right index.
         final int shellPageIdx =
             keyToPages.putIfAbsent(routeNavKey, () => <Page<Object?>>[]).length;

         // Find the the navigator key for the sub-route of this shell route.
         final RouteBase subRoute = matchList.matches[startIndex + 1].route;
         final GlobalKey<NavigatorState> shellNavigatorKey =
             route.navigatorKeyForSubRoute(subRoute);

         keyToPages.putIfAbsent(shellNavigatorKey, () => <Page<Object?>>[]);

         // Build the remaining pages
         _buildRecursive(context, matchList, startIndex + 1, pagePopContext,
             routerNeglect, keyToPages, shellNavigatorKey, registry);

         final HeroController heroController = _goHeroCache.putIfAbsent(
             shellNavigatorKey, () => _getHeroController(context));

         // Build the Navigator for this shell route
         Widget buildShellNavigator(
             List<NavigatorObserver>? observers, String? restorationScopeId) {
           return _buildNavigator(
             pagePopContext.onPopPage,
             keyToPages[shellNavigatorKey]!,
             shellNavigatorKey,
             observers: observers ?? const <NavigatorObserver>[],
             restorationScopeId: restorationScopeId,
             heroController: heroController,
           );
         }

         // Call the ShellRouteBase to create/update the shell route state
         final ShellRouteContext shellRouteContext = ShellRouteContext(
           route: route,
           routerState: state,
           navigatorKey: shellNavigatorKey,
           routeMatchList: matchList,
           navigatorBuilder: buildShellNavigator,
         );

         // Build the Page for this route
         page = _buildPageForShellRoute(
             context, state, match, route, pagePopContext, shellRouteContext);
         // Place the ShellRoute's Page onto the list for the parent navigator.
         keyToPages[routeNavKey]!.insert(shellPageIdx, page);
       }
     }
     if (page != null) {
       registry[page] = state;
       pagePopContext._setRouteMatchForPage(page, match);
     } else {
       throw GoError('Unsupported route type $route');
     }
   }

   static Widget _buildNavigator(
     PopPageCallback onPopPage,
     List<Page<Object?>> pages,
     Key? navigatorKey, {
     List<NavigatorObserver> observers = const <NavigatorObserver>[],
     String? restorationScopeId,
     HeroController? heroController,
   }) {
     final Widget navigator = Navigator(
       key: navigatorKey,
       restorationScopeId: restorationScopeId,
       pages: pages,
       observers: observers,
       onPopPage: onPopPage,
     );
     if (heroController != null) {
       return HeroControllerScope(
         controller: heroController,
         child: navigator,
       );
     } else {
       return navigator;
     }
   }

   /// Helper method that builds a [GoRouterState] object for the given [match]
   /// and [pathParameters].
   @visibleForTesting
   GoRouterState buildState(RouteMatchList matchList, RouteMatch match) {
     final RouteBase route = match.route;
     String? name;
     String path = '';
     if (route is GoRoute) {
       name = route.name;
       path = route.path;
     }
     final RouteMatchList effectiveMatchList;
     if (match is ImperativeRouteMatch) {
       effectiveMatchList = match.matches;
       if (effectiveMatchList.isError) {
         return _buildErrorState(effectiveMatchList);
       }
     } else {
       effectiveMatchList = matchList;
       assert(!effectiveMatchList.isError);
     }
     return GoRouterState(
       configuration,
       location: effectiveMatchList.uri.toString(),
       matchedLocation: match.matchedLocation,
       name: name,
       path: path,
       fullPath: effectiveMatchList.fullPath,
       pathParameters:
           Map<String, String>.from(effectiveMatchList.pathParameters),
       error: effectiveMatchList.error,
       queryParameters: effectiveMatchList.uri.queryParameters,
       queryParametersAll: effectiveMatchList.uri.queryParametersAll,
       extra: effectiveMatchList.extra,
       pageKey: match.pageKey,
     );
   }

   /// Builds a [Page] for [GoRoute]
   Page<Object?> _buildPageForGoRoute(BuildContext context, GoRouterState state,
       RouteMatch match, GoRoute route, _PagePopContext pagePopContext) {
     Page<Object?>? page;

     // Call the pageBuilder if it's non-null
     final GoRouterPageBuilder? pageBuilder = route.pageBuilder;
     if (pageBuilder != null) {
       page = pageBuilder(context, state);
       if (page is NoOpPage) {
         page = null;
       }
     }

     // Return the result of the route's builder() or pageBuilder()
     return page ??
         buildPage(context, state, Builder(builder: (BuildContext context) {
           return _callGoRouteBuilder(context, state, route);
         }));
   }

   /// Calls the user-provided route builder from the [GoRoute].
   Widget _callGoRouteBuilder(
       BuildContext context, GoRouterState state, GoRoute route) {
     final GoRouterWidgetBuilder? builder = route.builder;

     if (builder == null) {
       throw GoError('No routeBuilder provided to GoRoute: $route');
     }

     return builder(context, state);
   }

   /// Builds a [Page] for [ShellRouteBase]
   Page<Object?> _buildPageForShellRoute(
       BuildContext context,
       GoRouterState state,
       RouteMatch match,
       ShellRouteBase route,
       _PagePopContext pagePopContext,
       ShellRouteContext shellRouteContext) {
     Page<Object?>? page = route.buildPage(context, state, shellRouteContext);
     if (page is NoOpPage) {
       page = null;
     }

     // Return the result of the route's builder() or pageBuilder()
     return page ??
         buildPage(context, state, Builder(builder: (BuildContext context) {
           return _callShellRouteBaseBuilder(
               context, state, route, shellRouteContext);
         }));
   }

   /// Calls the user-provided route builder from the [ShellRouteBase].
   Widget _callShellRouteBaseBuilder(BuildContext context, GoRouterState state,
       ShellRouteBase route, ShellRouteContext? shellRouteContext) {
     assert(shellRouteContext != null,
         'ShellRouteContext must be provided for ${route.runtimeType}');
     final Widget? widget =
         route.buildWidget(context, state, shellRouteContext!);
     if (widget == null) {
       throw GoError('No builder provided to ShellRoute: $route');
     }

     return widget;
   }

   _PageBuilderForAppType? _pageBuilderForAppType;

   Widget Function(
     BuildContext context,
     GoRouterState state,
   )? _errorBuilderForAppType;

   void _cacheAppType(BuildContext context) {
     // cache app type-specific page and error builders
     if (_pageBuilderForAppType == null) {
       assert(_errorBuilderForAppType == null);

       // can be null during testing
       final Element? elem = context is Element ? context : null;

       if (elem != null && isMaterialApp(elem)) {
         log.info('Using MaterialApp configuration');
         _pageBuilderForAppType = pageBuilderForMaterialApp;
         _errorBuilderForAppType =
             (BuildContext c, GoRouterState s) => MaterialErrorScreen(s.error);
       } else if (elem != null && isCupertinoApp(elem)) {
         log.info('Using CupertinoApp configuration');
         _pageBuilderForAppType = pageBuilderForCupertinoApp;
         _errorBuilderForAppType =
             (BuildContext c, GoRouterState s) => CupertinoErrorScreen(s.error);
       } else {
         log.info('Using WidgetsApp configuration');
         _pageBuilderForAppType = pageBuilderForWidgetApp;
         _errorBuilderForAppType =
             (BuildContext c, GoRouterState s) => ErrorScreen(s.error);
       }
     }

     assert(_pageBuilderForAppType != null);
     assert(_errorBuilderForAppType != null);
   }

   /// builds the page based on app type, i.e. MaterialApp vs. CupertinoApp
   @visibleForTesting
   Page<Object?> buildPage(
     BuildContext context,
     GoRouterState state,
     Widget child,
   ) {
     // build the page based on app type
     _cacheAppType(context);
     return _pageBuilderForAppType!(
       key: state.pageKey,
       name: state.name ?? state.path,
       arguments: <String, String>{
         ...state.pathParameters,
         ...state.queryParameters
       },
       restorationId: state.pageKey.value,
       child: child,
     );
   }

   /// Builds a page without any transitions.
   Page<void> pageBuilderForWidgetApp({
     required LocalKey key,
     required String? name,
     required Object? arguments,
     required String restorationId,
     required Widget child,
   }) =>
       NoTransitionPage<void>(
         name: name,
         arguments: arguments,
         key: key,
         restorationId: restorationId,
         child: child,
       );

   GoRouterState _buildErrorState(RouteMatchList matchList) {
     final String location = matchList.uri.toString();
     assert(matchList.isError);
     return GoRouterState(
       configuration,
       location: location,
       matchedLocation: matchList.uri.path,
       fullPath: matchList.fullPath,
       pathParameters: matchList.pathParameters,
       queryParameters: matchList.uri.queryParameters,
       queryParametersAll: matchList.uri.queryParametersAll,
       error: matchList.error,
       pageKey: ValueKey<String>('$location(error)'),
     );
   }

   /// Builds a an error page.
   Page<void> _buildErrorPage(BuildContext context, GoRouterState state) {
     assert(state.error != null);

     // If the error page builder is provided, use that, otherwise, if the error
     // builder is provided, wrap that in an app-specific page (for example,
     // MaterialPage). Finally, if nothing is provided, use a default error page
     // wrapped in the app-specific page.
     _cacheAppType(context);
     final GoRouterWidgetBuilder? errorBuilder = this.errorBuilder;
     return errorPageBuilder != null
         ? errorPageBuilder!(context, state)
         : buildPage(
             context,
             state,
             errorBuilder != null
                 ? errorBuilder(context, state)
                 : _errorBuilderForAppType!(context, state),
           );
   }

   /// Return a HeroController based on the app type.
   HeroController _getHeroController(BuildContext context) {
     if (context is Element) {
       if (isMaterialApp(context)) {
         return createMaterialHeroController();
       } else if (isCupertinoApp(context)) {
         return createCupertinoHeroController();
       }
     }
     return HeroController();
   }
 }

 typedef _PageBuilderForAppType = Page<void> Function({
   required LocalKey key,
   required String? name,
   required Object? arguments,
   required String restorationId,
   required Widget child,
 });

 /// Context used to provide a route to page association when popping routes.
 class _PagePopContext {
   _PagePopContext._(this.onPopPageWithRouteMatch);

   final Map<Page<dynamic>, RouteMatch> _routeMatchLookUp =
       <Page<Object?>, RouteMatch>{};

   /// On pop page callback that includes the associated [RouteMatch].
   final PopPageWithRouteMatchCallback onPopPageWithRouteMatch;

   /// Looks for the [RouteMatch] for a given [Page].
   ///
   /// The [Page] must have been previously built via the [RouteBuilder] that
   /// created this [PagePopContext]; otherwise, this method returns null.
   RouteMatch? getRouteMatchForPage(Page<Object?> page) =>
       _routeMatchLookUp[page];

   void _setRouteMatchForPage(Page<Object?> page, RouteMatch match) =>
       _routeMatchLookUp[page] = match;

   /// Function used as [Navigator.onPopPage] callback when creating Navigators.
   ///
   /// This function forwards to [onPopPageWithRouteMatch], including the
   /// [RouteMatch] associated with the popped route.
   bool onPopPage(Route<dynamic> route, dynamic result) {
     final Page<Object?> page = route.settings as Page<Object?>;
     return onPopPageWithRouteMatch(route, result, _routeMatchLookUp[page]);
   }
 }
	// 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/widgets.dart';

	import '../go_router.dart';
	import 'configuration.dart';
	import 'logging.dart';
	import 'match.dart';
	import 'misc/error_screen.dart';
	import 'misc/errors.dart';
	import 'pages/cupertino.dart';
	import 'pages/material.dart';
	import 'route_data.dart';
	import 'typedefs.dart';

	/// Signature for a function that takes in a `route` to be popped with
	/// the `result` and returns a boolean decision on whether the pop
	/// is successful.
	///
	/// The `match` is the corresponding [RouteMatch] the `route`
	/// associates with.
	///
	/// Used by of [RouteBuilder.onPopPageWithRouteMatch].
	typedef PopPageWithRouteMatchCallback = bool Function(
	Route<dynamic> route, dynamic result, RouteMatch? match);

	/// Builds the top-level Navigator for GoRouter.
	class RouteBuilder {
	/// [RouteBuilder] constructor.
	RouteBuilder({
	required this.configuration,
	required this.builderWithNav,
	required this.errorPageBuilder,
	required this.errorBuilder,
	required this.restorationScopeId,
	required this.observers,
	required this.onPopPageWithRouteMatch,
	});

	/// Builder function for a go router with Navigator.
	final GoRouterBuilderWithNav builderWithNav;

	/// Error page builder for the go router delegate.
	final GoRouterPageBuilder? errorPageBuilder;

	/// Error widget builder for the go router delegate.
	final GoRouterWidgetBuilder? errorBuilder;

	/// The route configuration for the app.
	final RouteConfiguration configuration;

	/// Restoration ID to save and restore the state of the navigator, including
	/// its history.
	final String? restorationScopeId;

	/// NavigatorObserver used to receive notifications when navigating in between routes.
	/// changes.
	final List<NavigatorObserver> observers;

	final GoRouterStateRegistry _registry = GoRouterStateRegistry();

	/// A callback called when a `route` produced by `match` is about to be popped
	/// with the `result`.
	///
	/// If this method returns true, this builder pops the `route` and `match`.
	///
	/// If this method returns false, this builder aborts the pop.
	final PopPageWithRouteMatchCallback onPopPageWithRouteMatch;

	/// Caches a HeroController for the nested Navigator, which solves cases where the
	/// Hero Widget animation stops working when navigating.
	// TODO(chunhtai): Remove _goHeroCache once below issue is fixed:
	// https://github.com/flutter/flutter/issues/54200
	final Map<GlobalKey<NavigatorState>, HeroController> _goHeroCache =
	<GlobalKey<NavigatorState>, HeroController>{};

	/// Builds the top-level Navigator for the given [RouteMatchList].
	Widget build(
	BuildContext context,
	RouteMatchList matchList,
	bool routerNeglect,
	) {
	if (matchList.isEmpty && !matchList.isError) {
	// The build method can be called before async redirect finishes. Build a
	// empty box until then.
	return const SizedBox.shrink();
	}
	return builderWithNav(
	context,
	Builder(
	builder: (BuildContext context) {
	final Map<Page<Object?>, GoRouterState> newRegistry =
	<Page<Object?>, GoRouterState>{};
	final Widget result = tryBuild(context, matchList, routerNeglect,
	configuration.navigatorKey, newRegistry);
	_registry.updateRegistry(newRegistry);
	return GoRouterStateRegistryScope(registry: _registry, child: result);
	},
	),
	);
	}

	/// Builds the top-level Navigator by invoking the build method on each
	/// matching route.
	///
	/// Throws a [_RouteBuilderError].
	@visibleForTesting
	Widget tryBuild(
	BuildContext context,
	RouteMatchList matchList,
	bool routerNeglect,
	GlobalKey<NavigatorState> navigatorKey,
	Map<Page<Object?>, GoRouterState> registry,
	) {
	// TODO(chunhtai): move the state from local scope to a central place.
	// https://github.com/flutter/flutter/issues/126365
	final _PagePopContext pagePopContext =
	_PagePopContext._(onPopPageWithRouteMatch);
	return builderWithNav(
	context,
	_buildNavigator(
	pagePopContext.onPopPage,
	_buildPages(context, matchList, pagePopContext, routerNeglect,
	navigatorKey, registry),
	navigatorKey,
	observers: observers,
	restorationScopeId: restorationScopeId,
	),
	);
	}

	/// Returns the top-level pages instead of the root navigator. Used for
	/// testing.
	List<Page<Object?>> _buildPages(
	BuildContext context,
	RouteMatchList matchList,
	_PagePopContext pagePopContext,
	bool routerNeglect,
	GlobalKey<NavigatorState> navigatorKey,
	Map<Page<Object?>, GoRouterState> registry) {
	final Map<GlobalKey<NavigatorState>, List<Page<Object?>>> keyToPage;
	if (matchList.isError) {
	keyToPage = <GlobalKey<NavigatorState>, List<Page<Object?>>>{
	navigatorKey: <Page<Object?>>[
	_buildErrorPage(context, _buildErrorState(matchList)),
	]
	};
	} else {
	keyToPage = <GlobalKey<NavigatorState>, List<Page<Object?>>>{};
	_buildRecursive(context, matchList, 0, pagePopContext, routerNeglect,
	keyToPage, navigatorKey, registry);

	// Every Page should have a corresponding RouteMatch.
	assert(keyToPage.values.flattened.every((Page<Object?> page) =>
	pagePopContext.getRouteMatchForPage(page) != null));
	}

	/// Clean up previous cache to prevent memory leak, making sure any nested
	/// stateful shell routes for the current match list are kept.
	final Set<Key> activeKeys = keyToPage.keys.toSet()
	..addAll(_nestedStatefulNavigatorKeys(matchList));
	_goHeroCache.removeWhere(
	(GlobalKey<NavigatorState> key, _) => !activeKeys.contains(key));
	return keyToPage[navigatorKey]!;
	}

	static Set<GlobalKey<NavigatorState>> _nestedStatefulNavigatorKeys(
	RouteMatchList matchList) {
	final StatefulShellRoute? shellRoute =
	matchList.routes.whereType<StatefulShellRoute>().firstOrNull;
	if (shellRoute == null) {
	return <GlobalKey<NavigatorState>>{};
	}
	return RouteBase.routesRecursively(<RouteBase>[shellRoute])
	.whereType<StatefulShellRoute>()
	.expand((StatefulShellRoute e) =>
	e.branches.map((StatefulShellBranch b) => b.navigatorKey))
	.toSet();
	}

	void _buildRecursive(
	BuildContext context,
	RouteMatchList matchList,
	int startIndex,
	_PagePopContext pagePopContext,
	bool routerNeglect,
	Map<GlobalKey<NavigatorState>, List<Page<Object?>>> keyToPages,
	GlobalKey<NavigatorState> navigatorKey,
	Map<Page<Object?>, GoRouterState> registry,
	) {
	if (startIndex >= matchList.matches.length) {
	return;
	}
	final RouteMatch match = matchList.matches[startIndex];

	final RouteBase route = match.route;
	final GoRouterState state = buildState(matchList, match);
	Page<Object?>? page;
	if (state.error != null) {
	page = _buildErrorPage(context, state);
	keyToPages.putIfAbsent(navigatorKey, () => <Page<Object?>>[]).add(page);
	_buildRecursive(context, matchList, startIndex + 1, pagePopContext,
	routerNeglect, keyToPages, navigatorKey, registry);
	} else {
	// If this RouteBase is for a different Navigator, add it to the
	// list of out of scope pages
	final GlobalKey<NavigatorState> routeNavKey =
	route.parentNavigatorKey ?? navigatorKey;
	if (route is GoRoute) {
	page =
	_buildPageForGoRoute(context, state, match, route, pagePopContext);

	keyToPages.putIfAbsent(routeNavKey, () => <Page<Object?>>[]).add(page);

	_buildRecursive(context, matchList, startIndex + 1, pagePopContext,
	routerNeglect, keyToPages, navigatorKey, registry);
	} else if (route is ShellRouteBase) {
	assert(startIndex + 1 < matchList.matches.length,
	'Shell routes must always have child routes');

	// Add an entry for the parent navigator if none exists.
	//
	// Calling _buildRecursive can result in adding pages to the
	// parentNavigatorKey entry's list. Store the current length so
	// that the page for this ShellRoute is placed at the right index.
	final int shellPageIdx =
	keyToPages.putIfAbsent(routeNavKey, () => <Page<Object?>>[]).length;

	// Find the the navigator key for the sub-route of this shell route.
	final RouteBase subRoute = matchList.matches[startIndex + 1].route;
	final GlobalKey<NavigatorState> shellNavigatorKey =
	route.navigatorKeyForSubRoute(subRoute);

	keyToPages.putIfAbsent(shellNavigatorKey, () => <Page<Object?>>[]);

	// Build the remaining pages
	_buildRecursive(context, matchList, startIndex + 1, pagePopContext,
	routerNeglect, keyToPages, shellNavigatorKey, registry);

	final HeroController heroController = _goHeroCache.putIfAbsent(
	shellNavigatorKey, () => _getHeroController(context));

	// Build the Navigator for this shell route
	Widget buildShellNavigator(
	List<NavigatorObserver>? observers, String? restorationScopeId) {
	return _buildNavigator(
	pagePopContext.onPopPage,
	keyToPages[shellNavigatorKey]!,
	shellNavigatorKey,
	observers: observers ?? const <NavigatorObserver>[],
	restorationScopeId: restorationScopeId,
	heroController: heroController,
	);
	}

	// Call the ShellRouteBase to create/update the shell route state
	final ShellRouteContext shellRouteContext = ShellRouteContext(
	route: route,
	routerState: state,
	navigatorKey: shellNavigatorKey,
	routeMatchList: matchList,
	navigatorBuilder: buildShellNavigator,
	);

	// Build the Page for this route
	page = _buildPageForShellRoute(
	context, state, match, route, pagePopContext, shellRouteContext);
	// Place the ShellRoute's Page onto the list for the parent navigator.
	keyToPages[routeNavKey]!.insert(shellPageIdx, page);
	}
	}
	if (page != null) {
	registry[page] = state;
	pagePopContext._setRouteMatchForPage(page, match);
	} else {
	throw GoError('Unsupported route type $route');
	}
	}

	static Widget _buildNavigator(
	PopPageCallback onPopPage,
	List<Page<Object?>> pages,
	Key? navigatorKey, {
	List<NavigatorObserver> observers = const <NavigatorObserver>[],
	String? restorationScopeId,
	HeroController? heroController,
	}) {
	final Widget navigator = Navigator(
	key: navigatorKey,
	restorationScopeId: restorationScopeId,
	pages: pages,
	observers: observers,
	onPopPage: onPopPage,
	);
	if (heroController != null) {
	return HeroControllerScope(
	controller: heroController,
	child: navigator,
	);
	} else {
	return navigator;
	}
	}

	/// Helper method that builds a [GoRouterState] object for the given [match]
	/// and [pathParameters].
	@visibleForTesting
	GoRouterState buildState(RouteMatchList matchList, RouteMatch match) {
	final RouteBase route = match.route;
	String? name;
	String path = '';
	if (route is GoRoute) {
	name = route.name;
	path = route.path;
	}
	final RouteMatchList effectiveMatchList;
	if (match is ImperativeRouteMatch) {
	effectiveMatchList = match.matches;
	if (effectiveMatchList.isError) {
	return _buildErrorState(effectiveMatchList);
	}
	} else {
	effectiveMatchList = matchList;
	assert(!effectiveMatchList.isError);
	}
	return GoRouterState(
	configuration,
	location: effectiveMatchList.uri.toString(),
	matchedLocation: match.matchedLocation,
	name: name,
	path: path,
	fullPath: effectiveMatchList.fullPath,
	pathParameters:
	Map<String, String>.from(effectiveMatchList.pathParameters),
	error: effectiveMatchList.error,
	queryParameters: effectiveMatchList.uri.queryParameters,
	queryParametersAll: effectiveMatchList.uri.queryParametersAll,
	extra: effectiveMatchList.extra,
	pageKey: match.pageKey,
	);
	}

	/// Builds a [Page] for [GoRoute]
	Page<Object?> _buildPageForGoRoute(BuildContext context, GoRouterState state,
	RouteMatch match, GoRoute route, _PagePopContext pagePopContext) {
	Page<Object?>? page;

	// Call the pageBuilder if it's non-null
	final GoRouterPageBuilder? pageBuilder = route.pageBuilder;
	if (pageBuilder != null) {
	page = pageBuilder(context, state);
	if (page is NoOpPage) {
	page = null;
	}
	}

	// Return the result of the route's builder() or pageBuilder()
	return page ??
	buildPage(context, state, Builder(builder: (BuildContext context) {
	return _callGoRouteBuilder(context, state, route);
	}));
	}

	/// Calls the user-provided route builder from the [GoRoute].
	Widget _callGoRouteBuilder(
	BuildContext context, GoRouterState state, GoRoute route) {
	final GoRouterWidgetBuilder? builder = route.builder;

	if (builder == null) {
	throw GoError('No routeBuilder provided to GoRoute: $route');
	}

	return builder(context, state);
	}

	/// Builds a [Page] for [ShellRouteBase]
	Page<Object?> _buildPageForShellRoute(
	BuildContext context,
	GoRouterState state,
	RouteMatch match,
	ShellRouteBase route,
	_PagePopContext pagePopContext,
	ShellRouteContext shellRouteContext) {
	Page<Object?>? page = route.buildPage(context, state, shellRouteContext);
	if (page is NoOpPage) {
	page = null;
	}

	// Return the result of the route's builder() or pageBuilder()
	return page ??
	buildPage(context, state, Builder(builder: (BuildContext context) {
	return _callShellRouteBaseBuilder(
	context, state, route, shellRouteContext);
	}));
	}

	/// Calls the user-provided route builder from the [ShellRouteBase].
	Widget _callShellRouteBaseBuilder(BuildContext context, GoRouterState state,
	ShellRouteBase route, ShellRouteContext? shellRouteContext) {
	assert(shellRouteContext != null,
	'ShellRouteContext must be provided for ${route.runtimeType}');
	final Widget? widget =
	route.buildWidget(context, state, shellRouteContext!);
	if (widget == null) {
	throw GoError('No builder provided to ShellRoute: $route');
	}

	return widget;
	}

	_PageBuilderForAppType? _pageBuilderForAppType;

	Widget Function(
	BuildContext context,
	GoRouterState state,
	)? _errorBuilderForAppType;

	void _cacheAppType(BuildContext context) {
	// cache app type-specific page and error builders
	if (_pageBuilderForAppType == null) {
	assert(_errorBuilderForAppType == null);

	// can be null during testing
	final Element? elem = context is Element ? context : null;

	if (elem != null && isMaterialApp(elem)) {
	log.info('Using MaterialApp configuration');
	_pageBuilderForAppType = pageBuilderForMaterialApp;
	_errorBuilderForAppType =
	(BuildContext c, GoRouterState s) => MaterialErrorScreen(s.error);
	} else if (elem != null && isCupertinoApp(elem)) {
	log.info('Using CupertinoApp configuration');
	_pageBuilderForAppType = pageBuilderForCupertinoApp;
	_errorBuilderForAppType =
	(BuildContext c, GoRouterState s) => CupertinoErrorScreen(s.error);
	} else {
	log.info('Using WidgetsApp configuration');
	_pageBuilderForAppType = pageBuilderForWidgetApp;
	_errorBuilderForAppType =
	(BuildContext c, GoRouterState s) => ErrorScreen(s.error);
	}
	}

	assert(_pageBuilderForAppType != null);
	assert(_errorBuilderForAppType != null);
	}

	/// builds the page based on app type, i.e. MaterialApp vs. CupertinoApp
	@visibleForTesting
	Page<Object?> buildPage(
	BuildContext context,
	GoRouterState state,
	Widget child,
	) {
	// build the page based on app type
	_cacheAppType(context);
	return _pageBuilderForAppType!(
	key: state.pageKey,
	name: state.name ?? state.path,
	arguments: <String, String>{
	...state.pathParameters,
	...state.queryParameters
	},
	restorationId: state.pageKey.value,
	child: child,
	);
	}

	/// Builds a page without any transitions.
	Page<void> pageBuilderForWidgetApp({
	required LocalKey key,
	required String? name,
	required Object? arguments,
	required String restorationId,
	required Widget child,
	}) =>
	NoTransitionPage<void>(
	name: name,
	arguments: arguments,
	key: key,
	restorationId: restorationId,
	child: child,
	);

	GoRouterState _buildErrorState(RouteMatchList matchList) {
	final String location = matchList.uri.toString();
	assert(matchList.isError);
	return GoRouterState(
	configuration,
	location: location,
	matchedLocation: matchList.uri.path,
	fullPath: matchList.fullPath,
	pathParameters: matchList.pathParameters,
	queryParameters: matchList.uri.queryParameters,
	queryParametersAll: matchList.uri.queryParametersAll,
	error: matchList.error,
	pageKey: ValueKey<String>('$location(error)'),
	);
	}

	/// Builds a an error page.
	Page<void> _buildErrorPage(BuildContext context, GoRouterState state) {
	assert(state.error != null);

	// If the error page builder is provided, use that, otherwise, if the error
	// builder is provided, wrap that in an app-specific page (for example,
	// MaterialPage). Finally, if nothing is provided, use a default error page
	// wrapped in the app-specific page.
	_cacheAppType(context);
	final GoRouterWidgetBuilder? errorBuilder = this.errorBuilder;
	return errorPageBuilder != null
	? errorPageBuilder!(context, state)
	: buildPage(
	context,
	state,
	errorBuilder != null
	? errorBuilder(context, state)
	: _errorBuilderForAppType!(context, state),
	);
	}

	/// Return a HeroController based on the app type.
	HeroController _getHeroController(BuildContext context) {
	if (context is Element) {
	if (isMaterialApp(context)) {
	return createMaterialHeroController();
	} else if (isCupertinoApp(context)) {
	return createCupertinoHeroController();
	}
	}
	return HeroController();
	}
	}

	typedef _PageBuilderForAppType = Page<void> Function({
	required LocalKey key,
	required String? name,
	required Object? arguments,
	required String restorationId,
	required Widget child,
	});

	/// Context used to provide a route to page association when popping routes.
	class _PagePopContext {
	_PagePopContext._(this.onPopPageWithRouteMatch);

	final Map<Page<dynamic>, RouteMatch> _routeMatchLookUp =
	<Page<Object?>, RouteMatch>{};

	/// On pop page callback that includes the associated [RouteMatch].
	final PopPageWithRouteMatchCallback onPopPageWithRouteMatch;

	/// Looks for the [RouteMatch] for a given [Page].
	///
	/// The [Page] must have been previously built via the [RouteBuilder] that
	/// created this [PagePopContext]; otherwise, this method returns null.
	RouteMatch? getRouteMatchForPage(Page<Object?> page) =>
	_routeMatchLookUp[page];

	void _setRouteMatchForPage(Page<Object?> page, RouteMatch match) =>
	_routeMatchLookUp[page] = match;

	/// Function used as [Navigator.onPopPage] callback when creating Navigators.
	///
	/// This function forwards to [onPopPageWithRouteMatch], including the
	/// [RouteMatch] associated with the popped route.
	bool onPopPage(Route<dynamic> route, dynamic result) {
	final Page<Object?> page = route.settings as Page<Object?>;
	return onPopPageWithRouteMatch(route, result, _routeMatchLookUp[page]);
	}
	}