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:flutter/widgets.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/custom_transition_page.dart';
 import 'pages/material.dart';
 import 'route.dart';
 import 'route_data.dart';
 import 'state.dart';

 /// Signature of a go router builder function with navigator.
 typedef GoRouterBuilderWithNav = Widget Function(
   BuildContext context,
   Widget child,
 );

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

 typedef _ErrorBuilderForAppType = Widget Function(
   BuildContext context,
   GoRouterState state,
 );

 /// 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, RouteMatchBase 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,
     this.requestFocus = true,
   });

   /// 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;

   /// Whether or not the navigator created by this builder and it's new topmost route should request focus
   /// when the new route is pushed onto the navigator.
   ///
   /// Defaults to true.
   final bool requestFocus;

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

   /// 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;

   /// 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();
     }
     assert(matchList.isError || !matchList.last.route.redirectOnly);
     return builderWithNav(
       context,
       _CustomNavigator(
         navigatorKey: configuration.navigatorKey,
         observers: observers,
         navigatorRestorationId: restorationScopeId,
         onPopPageWithRouteMatch: onPopPageWithRouteMatch,
         matchList: matchList,
         matches: matchList.matches,
         configuration: configuration,
         errorBuilder: errorBuilder,
         errorPageBuilder: errorPageBuilder,
       ),
     );
   }
 }

 class _CustomNavigator extends StatefulWidget {
   const _CustomNavigator({
     super.key,
     required this.navigatorKey,
     required this.observers,
     required this.navigatorRestorationId,
     required this.onPopPageWithRouteMatch,
     required this.matchList,
     required this.matches,
     required this.configuration,
     required this.errorBuilder,
     required this.errorPageBuilder,
   });

   final GlobalKey<NavigatorState> navigatorKey;
   final List<NavigatorObserver> observers;

   /// The actual [RouteMatchBase]s to be built.
   ///
   /// This can be different from matches in [matchList] if this widget is used
   /// to build navigator in shell route. In this case, these matches come from
   /// the [ShellRouteMatch.matches].
   final List<RouteMatchBase> matches;
   final RouteMatchList matchList;
   final RouteConfiguration configuration;
   final PopPageWithRouteMatchCallback onPopPageWithRouteMatch;
   final String? navigatorRestorationId;
   final GoRouterWidgetBuilder? errorBuilder;
   final GoRouterPageBuilder? errorPageBuilder;

   @override
   State<StatefulWidget> createState() => _CustomNavigatorState();
 }

 class _CustomNavigatorState extends State<_CustomNavigator> {
   HeroController? _controller;
   late Map<Page<Object?>, RouteMatchBase> _pageToRouteMatchBase;
   final GoRouterStateRegistry _registry = GoRouterStateRegistry();
   List<Page<Object?>>? _pages;

   @override
   void didUpdateWidget(_CustomNavigator oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (widget.matchList != oldWidget.matchList) {
       _pages = null;
     }
   }

   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
     // Create a HeroController based on the app type.
     if (_controller == null) {
       if (isMaterialApp(context)) {
         _controller = createMaterialHeroController();
       } else if (isCupertinoApp(context)) {
         _controller = createCupertinoHeroController();
       } else {
         _controller = HeroController();
       }
     }
     // This method can also be called if any of the page builders depend on
     // the context. In this case, make sure _pages are rebuilt.
     _pages = null;
   }

   @override
   void dispose() {
     _controller?.dispose();
     _registry.dispose();
     super.dispose();
   }

   void _updatePages(BuildContext context) {
     assert(_pages == null);
     final List<Page<Object?>> pages = <Page<Object?>>[];
     final Map<Page<Object?>, RouteMatchBase> pageToRouteMatchBase =
         <Page<Object?>, RouteMatchBase>{};
     final Map<Page<Object?>, GoRouterState> registry =
         <Page<Object?>, GoRouterState>{};
     if (widget.matchList.isError) {
       pages.add(_buildErrorPage(context, widget.matchList));
     } else {
       for (final RouteMatchBase match in widget.matches) {
         final Page<Object?>? page = _buildPage(context, match);
         if (page == null) {
           continue;
         }
         pages.add(page);
         pageToRouteMatchBase[page] = match;
         registry[page] =
             match.buildState(widget.configuration, widget.matchList);
       }
     }
     _pages = pages;
     _registry.updateRegistry(registry);
     _pageToRouteMatchBase = pageToRouteMatchBase;
   }

   Page<Object?>? _buildPage(BuildContext context, RouteMatchBase match) {
     if (match is RouteMatch) {
       if (match is ImperativeRouteMatch && match.matches.isError) {
         return _buildErrorPage(context, match.matches);
       }
       return _buildPageForGoRoute(context, match);
     }
     if (match is ShellRouteMatch) {
       return _buildPageForShellRoute(context, match);
     }
     throw GoError('unknown match type ${match.runtimeType}');
   }

   /// Builds a [Page] for a [RouteMatch]
   Page<Object?>? _buildPageForGoRoute(BuildContext context, RouteMatch match) {
     final GoRouterPageBuilder? pageBuilder = match.route.pageBuilder;
     final GoRouterState state =
         match.buildState(widget.configuration, widget.matchList);
     if (pageBuilder != null) {
       final Page<Object?> page = pageBuilder(context, state);
       if (page is! NoOpPage) {
         return page;
       }
     }

     final GoRouterWidgetBuilder? builder = match.route.builder;

     if (builder == null) {
       return null;
     }
     return _buildPlatformAdapterPage(context, state,
         Builder(builder: (BuildContext context) {
       return builder(context, state);
     }));
   }

   /// Builds a [Page] for a [ShellRouteMatch]
   Page<Object?> _buildPageForShellRoute(
     BuildContext context,
     ShellRouteMatch match,
   ) {
     final GoRouterState state =
         match.buildState(widget.configuration, widget.matchList);
     final GlobalKey<NavigatorState> navigatorKey = match.navigatorKey;
     final ShellRouteContext shellRouteContext = ShellRouteContext(
       route: match.route,
       routerState: state,
       navigatorKey: navigatorKey,
       routeMatchList: widget.matchList,
       navigatorBuilder:
           (List<NavigatorObserver>? observers, String? restorationScopeId) {
         return _CustomNavigator(
           // The state needs to persist across rebuild.
           key: GlobalObjectKey(navigatorKey.hashCode),
           navigatorRestorationId: restorationScopeId,
           navigatorKey: navigatorKey,
           matches: match.matches,
           matchList: widget.matchList,
           configuration: widget.configuration,
           observers: observers ?? const <NavigatorObserver>[],
           onPopPageWithRouteMatch: widget.onPopPageWithRouteMatch,
           // This is used to recursively build pages under this shell route.
           errorBuilder: widget.errorBuilder,
           errorPageBuilder: widget.errorPageBuilder,
         );
       },
     );
     final Page<Object?>? page =
         match.route.buildPage(context, state, shellRouteContext);
     if (page != null && page is! NoOpPage) {
       return page;
     }

     // Return the result of the route's builder() or pageBuilder()
     return _buildPlatformAdapterPage(
       context,
       state,
       Builder(
         builder: (BuildContext context) {
           return match.route.buildWidget(context, state, shellRouteContext)!;
         },
       ),
     );
   }

   _PageBuilderForAppType? _pageBuilderForAppType;

   _ErrorBuilderForAppType? _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('Using MaterialApp configuration');
         _pageBuilderForAppType = pageBuilderForMaterialApp;
         _errorBuilderForAppType =
             (BuildContext c, GoRouterState s) => MaterialErrorScreen(s.error);
       } else if (elem != null && isCupertinoApp(elem)) {
         log('Using CupertinoApp configuration');
         _pageBuilderForAppType = pageBuilderForCupertinoApp;
         _errorBuilderForAppType =
             (BuildContext c, GoRouterState s) => CupertinoErrorScreen(s.error);
       } else {
         log('Using WidgetsApp configuration');
         _pageBuilderForAppType = ({
           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,
             );
         _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
   Page<Object?> _buildPlatformAdapterPage(
     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.uri.queryParameters
       },
       restorationId: state.pageKey.value,
       child: child,
     );
   }

   GoRouterState _buildErrorState(RouteMatchList matchList) {
     assert(matchList.isError);
     return GoRouterState(
       widget.configuration,
       uri: matchList.uri,
       matchedLocation: matchList.uri.path,
       fullPath: matchList.fullPath,
       pathParameters: matchList.pathParameters,
       error: matchList.error,
       pageKey: ValueKey<String>('${matchList.uri}(error)'),
       topRoute: matchList.lastOrNull?.route,
     );
   }

   /// Builds a an error page.
   Page<void> _buildErrorPage(BuildContext context, RouteMatchList matchList) {
     final GoRouterState state = _buildErrorState(matchList);
     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 = widget.errorBuilder;
     return widget.errorPageBuilder != null
         ? widget.errorPageBuilder!(context, state)
         : _buildPlatformAdapterPage(
             context,
             state,
             errorBuilder != null
                 ? errorBuilder(context, state)
                 : _errorBuilderForAppType!(context, state),
           );
   }

   bool _handlePopPage(Route<Object?> route, Object? result) {
     final Page<Object?> page = route.settings as Page<Object?>;
     final RouteMatchBase match = _pageToRouteMatchBase[page]!;
     return widget.onPopPageWithRouteMatch(route, result, match);
   }

   @override
   Widget build(BuildContext context) {
     if (_pages == null) {
       _updatePages(context);
     }
     assert(_pages != null);
     return GoRouterStateRegistryScope(
       registry: _registry,
       child: HeroControllerScope(
         controller: _controller!,
         child: Navigator(
           key: widget.navigatorKey,
           restorationScopeId: widget.navigatorRestorationId,
           pages: _pages!,
           observers: widget.observers,
           onPopPage: _handlePopPage,
         ),
       ),
     );
   }
 }
	// 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';

	import 'configuration.dart';
	import 'logging.dart';
	import 'match.dart';
	import 'misc/error_screen.dart';
	import 'misc/errors.dart';
	import 'pages/cupertino.dart';
	import 'pages/custom_transition_page.dart';
	import 'pages/material.dart';
	import 'route.dart';
	import 'route_data.dart';
	import 'state.dart';

	/// Signature of a go router builder function with navigator.
	typedef GoRouterBuilderWithNav = Widget Function(
	BuildContext context,
	Widget child,
	);

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

	typedef _ErrorBuilderForAppType = Widget Function(
	BuildContext context,
	GoRouterState state,
	);

	/// 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, RouteMatchBase 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,
	this.requestFocus = true,
	});

	/// 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;

	/// Whether or not the navigator created by this builder and it's new topmost route should request focus
	/// when the new route is pushed onto the navigator.
	///
	/// Defaults to true.
	final bool requestFocus;

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

	/// 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;

	/// 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();
	}
	assert(matchList.isError \|\| !matchList.last.route.redirectOnly);
	return builderWithNav(
	context,
	_CustomNavigator(
	navigatorKey: configuration.navigatorKey,
	observers: observers,
	navigatorRestorationId: restorationScopeId,
	onPopPageWithRouteMatch: onPopPageWithRouteMatch,
	matchList: matchList,
	matches: matchList.matches,
	configuration: configuration,
	errorBuilder: errorBuilder,
	errorPageBuilder: errorPageBuilder,
	),
	);
	}
	}

	class _CustomNavigator extends StatefulWidget {
	const _CustomNavigator({
	super.key,
	required this.navigatorKey,
	required this.observers,
	required this.navigatorRestorationId,
	required this.onPopPageWithRouteMatch,
	required this.matchList,
	required this.matches,
	required this.configuration,
	required this.errorBuilder,
	required this.errorPageBuilder,
	});

	final GlobalKey<NavigatorState> navigatorKey;
	final List<NavigatorObserver> observers;

	/// The actual [RouteMatchBase]s to be built.
	///
	/// This can be different from matches in [matchList] if this widget is used
	/// to build navigator in shell route. In this case, these matches come from
	/// the [ShellRouteMatch.matches].
	final List<RouteMatchBase> matches;
	final RouteMatchList matchList;
	final RouteConfiguration configuration;
	final PopPageWithRouteMatchCallback onPopPageWithRouteMatch;
	final String? navigatorRestorationId;
	final GoRouterWidgetBuilder? errorBuilder;
	final GoRouterPageBuilder? errorPageBuilder;

	@override
	State<StatefulWidget> createState() => _CustomNavigatorState();
	}

	class _CustomNavigatorState extends State<_CustomNavigator> {
	HeroController? _controller;
	late Map<Page<Object?>, RouteMatchBase> _pageToRouteMatchBase;
	final GoRouterStateRegistry _registry = GoRouterStateRegistry();
	List<Page<Object?>>? _pages;

	@override
	void didUpdateWidget(_CustomNavigator oldWidget) {
	super.didUpdateWidget(oldWidget);
	if (widget.matchList != oldWidget.matchList) {
	_pages = null;
	}
	}

	@override
	void didChangeDependencies() {
	super.didChangeDependencies();
	// Create a HeroController based on the app type.
	if (_controller == null) {
	if (isMaterialApp(context)) {
	_controller = createMaterialHeroController();
	} else if (isCupertinoApp(context)) {
	_controller = createCupertinoHeroController();
	} else {
	_controller = HeroController();
	}
	}
	// This method can also be called if any of the page builders depend on
	// the context. In this case, make sure _pages are rebuilt.
	_pages = null;
	}

	@override
	void dispose() {
	_controller?.dispose();
	_registry.dispose();
	super.dispose();
	}

	void _updatePages(BuildContext context) {
	assert(_pages == null);
	final List<Page<Object?>> pages = <Page<Object?>>[];
	final Map<Page<Object?>, RouteMatchBase> pageToRouteMatchBase =
	<Page<Object?>, RouteMatchBase>{};
	final Map<Page<Object?>, GoRouterState> registry =
	<Page<Object?>, GoRouterState>{};
	if (widget.matchList.isError) {
	pages.add(_buildErrorPage(context, widget.matchList));
	} else {
	for (final RouteMatchBase match in widget.matches) {
	final Page<Object?>? page = _buildPage(context, match);
	if (page == null) {
	continue;
	}
	pages.add(page);
	pageToRouteMatchBase[page] = match;
	registry[page] =
	match.buildState(widget.configuration, widget.matchList);
	}
	}
	_pages = pages;
	_registry.updateRegistry(registry);
	_pageToRouteMatchBase = pageToRouteMatchBase;
	}

	Page<Object?>? _buildPage(BuildContext context, RouteMatchBase match) {
	if (match is RouteMatch) {
	if (match is ImperativeRouteMatch && match.matches.isError) {
	return _buildErrorPage(context, match.matches);
	}
	return _buildPageForGoRoute(context, match);
	}
	if (match is ShellRouteMatch) {
	return _buildPageForShellRoute(context, match);
	}
	throw GoError('unknown match type ${match.runtimeType}');
	}

	/// Builds a [Page] for a [RouteMatch]
	Page<Object?>? _buildPageForGoRoute(BuildContext context, RouteMatch match) {
	final GoRouterPageBuilder? pageBuilder = match.route.pageBuilder;
	final GoRouterState state =
	match.buildState(widget.configuration, widget.matchList);
	if (pageBuilder != null) {
	final Page<Object?> page = pageBuilder(context, state);
	if (page is! NoOpPage) {
	return page;
	}
	}

	final GoRouterWidgetBuilder? builder = match.route.builder;

	if (builder == null) {
	return null;
	}
	return _buildPlatformAdapterPage(context, state,
	Builder(builder: (BuildContext context) {
	return builder(context, state);
	}));
	}

	/// Builds a [Page] for a [ShellRouteMatch]
	Page<Object?> _buildPageForShellRoute(
	BuildContext context,
	ShellRouteMatch match,
	) {
	final GoRouterState state =
	match.buildState(widget.configuration, widget.matchList);
	final GlobalKey<NavigatorState> navigatorKey = match.navigatorKey;
	final ShellRouteContext shellRouteContext = ShellRouteContext(
	route: match.route,
	routerState: state,
	navigatorKey: navigatorKey,
	routeMatchList: widget.matchList,
	navigatorBuilder:
	(List<NavigatorObserver>? observers, String? restorationScopeId) {
	return _CustomNavigator(
	// The state needs to persist across rebuild.
	key: GlobalObjectKey(navigatorKey.hashCode),
	navigatorRestorationId: restorationScopeId,
	navigatorKey: navigatorKey,
	matches: match.matches,
	matchList: widget.matchList,
	configuration: widget.configuration,
	observers: observers ?? const <NavigatorObserver>[],
	onPopPageWithRouteMatch: widget.onPopPageWithRouteMatch,
	// This is used to recursively build pages under this shell route.
	errorBuilder: widget.errorBuilder,
	errorPageBuilder: widget.errorPageBuilder,
	);
	},
	);
	final Page<Object?>? page =
	match.route.buildPage(context, state, shellRouteContext);
	if (page != null && page is! NoOpPage) {
	return page;
	}

	// Return the result of the route's builder() or pageBuilder()
	return _buildPlatformAdapterPage(
	context,
	state,
	Builder(
	builder: (BuildContext context) {
	return match.route.buildWidget(context, state, shellRouteContext)!;
	},
	),
	);
	}

	_PageBuilderForAppType? _pageBuilderForAppType;

	_ErrorBuilderForAppType? _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('Using MaterialApp configuration');
	_pageBuilderForAppType = pageBuilderForMaterialApp;
	_errorBuilderForAppType =
	(BuildContext c, GoRouterState s) => MaterialErrorScreen(s.error);
	} else if (elem != null && isCupertinoApp(elem)) {
	log('Using CupertinoApp configuration');
	_pageBuilderForAppType = pageBuilderForCupertinoApp;
	_errorBuilderForAppType =
	(BuildContext c, GoRouterState s) => CupertinoErrorScreen(s.error);
	} else {
	log('Using WidgetsApp configuration');
	_pageBuilderForAppType = ({
	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,
	);
	_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
	Page<Object?> _buildPlatformAdapterPage(
	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.uri.queryParameters
	},
	restorationId: state.pageKey.value,
	child: child,
	);
	}

	GoRouterState _buildErrorState(RouteMatchList matchList) {
	assert(matchList.isError);
	return GoRouterState(
	widget.configuration,
	uri: matchList.uri,
	matchedLocation: matchList.uri.path,
	fullPath: matchList.fullPath,
	pathParameters: matchList.pathParameters,
	error: matchList.error,
	pageKey: ValueKey<String>('${matchList.uri}(error)'),
	topRoute: matchList.lastOrNull?.route,
	);
	}

	/// Builds a an error page.
	Page<void> _buildErrorPage(BuildContext context, RouteMatchList matchList) {
	final GoRouterState state = _buildErrorState(matchList);
	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 = widget.errorBuilder;
	return widget.errorPageBuilder != null
	? widget.errorPageBuilder!(context, state)
	: _buildPlatformAdapterPage(
	context,
	state,
	errorBuilder != null
	? errorBuilder(context, state)
	: _errorBuilderForAppType!(context, state),
	);
	}

	bool _handlePopPage(Route<Object?> route, Object? result) {
	final Page<Object?> page = route.settings as Page<Object?>;
	final RouteMatchBase match = _pageToRouteMatchBase[page]!;
	return widget.onPopPageWithRouteMatch(route, result, match);
	}

	@override
	Widget build(BuildContext context) {
	if (_pages == null) {
	_updatePages(context);
	}
	assert(_pages != null);
	return GoRouterStateRegistryScope(
	registry: _registry,
	child: HeroControllerScope(
	controller: _controller!,
	child: Navigator(
	key: widget.navigatorKey,
	restorationScopeId: widget.navigatorRestorationId,
	pages: _pages!,
	observers: widget.observers,
	onPopPage: _handlePopPage,
	),
	),
	);
	}
	}