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// Copyright 2014 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.
// @dart = 2.8
import 'dart:async';
import 'dart:collection';
import 'dart:convert';
import 'dart:developer' as developer;
import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/scheduler.dart';
import 'package:flutter/services.dart';
import 'basic.dart';
import 'binding.dart';
import 'focus_manager.dart';
import 'focus_scope.dart';
import 'framework.dart';
import 'heroes.dart';
import 'overlay.dart';
import 'routes.dart';
import 'ticker_provider.dart';
// Examples can assume:
// class MyPage extends Placeholder { MyPage({String title}); }
// class MyHomePage extends Placeholder { }
// NavigatorState navigator;
// BuildContext context;
/// Creates a route for the given route settings.
///
/// Used by [Navigator.onGenerateRoute].
///
/// See also:
///
/// * [Navigator], which is where all the [Route]s end up.
typedef RouteFactory = Route<dynamic> Function(RouteSettings settings);
/// Creates a series of one or more routes.
///
/// Used by [Navigator.onGenerateInitialRoutes].
typedef RouteListFactory = List<Route<dynamic>> Function(NavigatorState navigator, String initialRoute);
/// Signature for the [Navigator.popUntil] predicate argument.
typedef RoutePredicate = bool Function(Route<dynamic> route);
/// Signature for a callback that verifies that it's OK to call [Navigator.pop].
///
/// Used by [Form.onWillPop], [ModalRoute.addScopedWillPopCallback],
/// [ModalRoute.removeScopedWillPopCallback], and [WillPopScope].
typedef WillPopCallback = Future<bool> Function();
/// Signature for the [Navigator.onPopPage] callback.
///
/// This callback must call [Route.didPop] on the specified route and must
/// properly update the pages list the next time it is passed into
/// [Navigator.pages] so that it no longer includes the corresponding [Page].
/// (Otherwise, the page will be interpreted as a new page to show when the
/// [Navigator.pages] list is next updated.)
typedef PopPageCallback = bool Function(Route<dynamic> route, dynamic result);
/// Indicates whether the current route should be popped.
///
/// Used as the return value for [Route.willPop].
///
/// See also:
///
/// * [WillPopScope], a widget that hooks into the route's [Route.willPop]
/// mechanism.
enum RoutePopDisposition {
/// Pop the route.
///
/// If [Route.willPop] returns [pop] then the back button will actually pop
/// the current route.
pop,
/// Do not pop the route.
///
/// If [Route.willPop] returns [doNotPop] then the back button will be ignored.
doNotPop,
/// Delegate this to the next level of navigation.
///
/// If [Route.willPop] returns [bubble] then the back button will be handled
/// by the [SystemNavigator], which will usually close the application.
bubble,
}
/// An abstraction for an entry managed by a [Navigator].
///
/// This class defines an abstract interface between the navigator and the
/// "routes" that are pushed on and popped off the navigator. Most routes have
/// visual affordances, which they place in the navigators [Overlay] using one
/// or more [OverlayEntry] objects.
///
/// See [Navigator] for more explanation of how to use a [Route] with
/// navigation, including code examples.
///
/// See [MaterialPageRoute] for a route that replaces the entire screen with a
/// platform-adaptive transition.
///
/// A route can belong to a page if the [settings] are a subclass of [Page]. A
/// page-based route, as opposed to a pageless route, is created from
/// [Page.createRoute] during [Navigator.pages] updates. The page associated
/// with this route may change during the lifetime of the route. If the
/// [Navigator] updates the page of this route, it calls [changedInternalState]
/// to notify the route that the page has been updated.
///
/// The type argument `T` is the route's return type, as used by
/// [currentResult], [popped], and [didPop]. The type `void` may be used if the
/// route does not return a value.
abstract class Route<T> {
/// Initialize the [Route].
///
/// If the [settings] are not provided, an empty [RouteSettings] object is
/// used instead.
Route({ RouteSettings settings }) : _settings = settings ?? const RouteSettings();
/// The navigator that the route is in, if any.
NavigatorState get navigator => _navigator;
NavigatorState _navigator;
/// The settings for this route.
///
/// See [RouteSettings] for details.
///
/// The settings can change during the route's lifetime. If the settings
/// change, the route's overlays will be marked dirty (see
/// [changedInternalState]).
///
/// If the route is created from a [Page] in the [Navigator.pages] list, then
/// this will be a [Page] subclass, and it will be updated each time its
/// corresponding [Page] in the [Navigator.pages] has changed. Once the
/// [Route] is removed from the history, this value stops updating (and
/// remains with its last value).
RouteSettings get settings => _settings;
RouteSettings _settings;
void _updateSettings(RouteSettings newSettings) {
assert(newSettings != null);
if (_settings != newSettings) {
_settings = newSettings;
changedInternalState();
}
}
/// The overlay entries of this route.
///
/// These are typically populated by [install]. The [Navigator] is in charge
/// of adding them to and removing them from the [Overlay].
///
/// There must be at least one entry in this list after [install] has been
/// invoked.
///
/// The [Navigator] will take care of keeping the entries together if the
/// route is moved in the history.
List<OverlayEntry> get overlayEntries => const <OverlayEntry>[];
/// Called when the route is inserted into the navigator.
///
/// Uses this to populate [overlayEntries]. There must be at least one entry in
/// this list after [install] has been invoked. The [Navigator] will be in charge
/// to add them to the [Overlay] or remove them from it by calling
/// [OverlayEntry.remove].
@protected
@mustCallSuper
void install() { }
/// Called after [install] when the route is pushed onto the navigator.
///
/// The returned value resolves when the push transition is complete.
///
/// The [didAdd] method will be called instead of [didPush] when the route
/// immediately appears on screen without any push transition.
///
/// The [didChangeNext] and [didChangePrevious] methods are typically called
/// immediately after this method is called.
@protected
@mustCallSuper
TickerFuture didPush() {
return TickerFuture.complete()..then<void>((void _) {
navigator?.focusScopeNode?.requestFocus();
});
}
/// Called after [install] when the route is added to the navigator.
///
/// This method is called instead of [didPush] when the route immediately
/// appears on screen without any push transition.
///
/// The [didChangeNext] and [didChangePrevious] methods are typically called
/// immediately after this method is called.
@protected
@mustCallSuper
void didAdd() {
// This TickerFuture serves two purposes. First, we want to make sure
// animations triggered by other operations finish before focusing the
// navigator. Second, navigator.focusScopeNode might acquire more focused
// children in Route.install asynchronously. This TickerFuture will wait for
// it to finish first.
//
// The later case can be found when subclasses manage their own focus scopes.
// For example, ModalRoute create a focus scope in its overlay entries. The
// focused child can only be attached to navigator after initState which
// will be guarded by the asynchronous gap.
TickerFuture.complete().then<void>((void _) {
// The route can be disposed before the ticker future completes. This can
// happen when the navigator is under a TabView that warps from one tab to
// another, non-adjacent tab, with an animation. The TabView reorders its
// children before and after the warping completes, and that causes its
// children to be built and disposed within the same frame. If one of its
// children contains a navigator, the routes in that navigator are also
// added and disposed within that frame.
//
// Since the reference to the navigator will be set to null after it is
// disposed, we have to do a null-safe operation in case that happens
// within the same frame when it is added.
navigator?.focusScopeNode?.requestFocus();
});
}
/// Called after [install] when the route replaced another in the navigator.
///
/// The [didChangeNext] and [didChangePrevious] methods are typically called
/// immediately after this method is called.
@protected
@mustCallSuper
void didReplace(Route<dynamic> oldRoute) { }
/// Returns whether calling [Navigator.maybePop] when this [Route] is current
/// ([isCurrent]) should do anything.
///
/// [Navigator.maybePop] is usually used instead of [Navigator.pop] to handle
/// the system back button.
///
/// By default, if a [Route] is the first route in the history (i.e., if
/// [isFirst]), it reports that pops should be bubbled
/// ([RoutePopDisposition.bubble]). This behavior prevents the user from
/// popping the first route off the history and being stranded at a blank
/// screen; instead, the larger scope is popped (e.g. the application quits,
/// so that the user returns to the previous application).
///
/// In other cases, the default behaviour is to accept the pop
/// ([RoutePopDisposition.pop]).
///
/// The third possible value is [RoutePopDisposition.doNotPop], which causes
/// the pop request to be ignored entirely.
///
/// See also:
///
/// * [Form], which provides a [Form.onWillPop] callback that uses this
/// mechanism.
/// * [WillPopScope], another widget that provides a way to intercept the
/// back button.
Future<RoutePopDisposition> willPop() async {
return isFirst ? RoutePopDisposition.bubble : RoutePopDisposition.pop;
}
/// Whether calling [didPop] would return false.
bool get willHandlePopInternally => false;
/// When this route is popped (see [Navigator.pop]) if the result isn't
/// specified or if it's null, this value will be used instead.
///
/// This fallback is implemented by [didComplete]. This value is used if the
/// argument to that method is null.
T get currentResult => null;
/// A future that completes when this route is popped off the navigator.
///
/// The future completes with the value given to [Navigator.pop], if any, or
/// else the value of [currentResult]. See [didComplete] for more discussion
/// on this topic.
Future<T> get popped => _popCompleter.future;
final Completer<T> _popCompleter = Completer<T>();
/// A request was made to pop this route. If the route can handle it
/// internally (e.g. because it has its own stack of internal state) then
/// return false, otherwise return true (by returning the value of calling
/// `super.didPop`). Returning false will prevent the default behavior of
/// [NavigatorState.pop].
///
/// When this function returns true, the navigator removes this route from
/// the history but does not yet call [dispose]. Instead, it is the route's
/// responsibility to call [NavigatorState.finalizeRoute], which will in turn
/// call [dispose] on the route. This sequence lets the route perform an
/// exit animation (or some other visual effect) after being popped but prior
/// to being disposed.
///
/// This method should call [didComplete] to resolve the [popped] future (and
/// this is all that the default implementation does); routes should not wait
/// for their exit animation to complete before doing so.
///
/// See [popped], [didComplete], and [currentResult] for a discussion of the
/// `result` argument.
@mustCallSuper
bool didPop(T result) {
didComplete(result);
return true;
}
/// The route was popped or is otherwise being removed somewhat gracefully.
///
/// This is called by [didPop] and in response to
/// [NavigatorState.pushReplacement]. If [didPop] was not called, then the
/// [NavigatorState.finalizeRoute] method must be called immediately, and no exit
/// animation will run.
///
/// The [popped] future is completed by this method. The `result` argument
/// specifies the value that this future is completed with, unless it is null,
/// in which case [currentResult] is used instead.
///
/// This should be called before the pop animation, if any, takes place,
/// though in some cases the animation may be driven by the user before the
/// route is committed to being popped; this can in particular happen with the
/// iOS-style back gesture. See [NavigatorState.didStartUserGesture].
@protected
@mustCallSuper
void didComplete(T result) {
_popCompleter.complete(result ?? currentResult);
}
/// The given route, which was above this one, has been popped off the
/// navigator.
///
/// This route is now the current route ([isCurrent] is now true), and there
/// is no next route.
@protected
@mustCallSuper
void didPopNext(Route<dynamic> nextRoute) { }
/// This route's next route has changed to the given new route.
///
/// This is called on a route whenever the next route changes for any reason,
/// so long as it is in the history, including when a route is first added to
/// a [Navigator] (e.g. by [Navigator.push]), except for cases when
/// [didPopNext] would be called.
///
/// The `nextRoute` argument will be null if there's no new next route (i.e.
/// if [isCurrent] is true).
@protected
@mustCallSuper
void didChangeNext(Route<dynamic> nextRoute) { }
/// This route's previous route has changed to the given new route.
///
/// This is called on a route whenever the previous route changes for any
/// reason, so long as it is in the history, except for immediately after the
/// route itself has been pushed (in which case [didPush] or [didReplace] will
/// be called instead).
///
/// The `previousRoute` argument will be null if there's no previous route
/// (i.e. if [isFirst] is true).
@protected
@mustCallSuper
void didChangePrevious(Route<dynamic> previousRoute) { }
/// Called whenever the internal state of the route has changed.
///
/// This should be called whenever [willHandlePopInternally], [didPop],
/// [ModalRoute.offstage], or other internal state of the route changes value.
/// It is used by [ModalRoute], for example, to report the new information via
/// its inherited widget to any children of the route.
///
/// See also:
///
/// * [changedExternalState], which is called when the [Navigator] rebuilds.
@protected
@mustCallSuper
void changedInternalState() { }
/// Called whenever the [Navigator] has its widget rebuilt, to indicate that
/// the route may wish to rebuild as well.
///
/// This is called by the [Navigator] whenever the [NavigatorState]'s
/// [State.widget] changes, for example because the [MaterialApp] has been rebuilt.
/// This ensures that routes that directly refer to the state of the widget
/// that built the [MaterialApp] will be notified when that widget rebuilds,
/// since it would otherwise be difficult to notify the routes that state they
/// depend on may have changed.
///
/// See also:
///
/// * [changedInternalState], the equivalent but for changes to the internal
/// state of the route.
@protected
@mustCallSuper
void changedExternalState() { }
/// Discards any resources used by the object.
///
/// This method should not remove its [overlayEntries] from the [Overlay]. The
/// object's owner is in charge of doing that.
///
/// After this is called, the object is not in a usable state and should be
/// discarded.
///
/// This method should only be called by the object's owner; typically the
/// [Navigator] owns a route and so will call this method when the route is
/// removed, after which the route is no longer referenced by the navigator.
@mustCallSuper
@protected
void dispose() {
_navigator = null;
}
/// Whether this route is the top-most route on the navigator.
///
/// If this is true, then [isActive] is also true.
bool get isCurrent {
if (_navigator == null)
return false;
final _RouteEntry currentRouteEntry = _navigator._history.lastWhere(
_RouteEntry.isPresentPredicate,
orElse: () => null,
);
if (currentRouteEntry == null)
return false;
return currentRouteEntry.route == this;
}
/// Whether this route is the bottom-most route on the navigator.
///
/// If this is true, then [Navigator.canPop] will return false if this route's
/// [willHandlePopInternally] returns false.
///
/// If [isFirst] and [isCurrent] are both true then this is the only route on
/// the navigator (and [isActive] will also be true).
bool get isFirst {
if (_navigator == null)
return false;
final _RouteEntry currentRouteEntry = _navigator._history.firstWhere(
_RouteEntry.isPresentPredicate,
orElse: () => null,
);
if (currentRouteEntry == null)
return false;
return currentRouteEntry.route == this;
}
/// Whether this route is on the navigator.
///
/// If the route is not only active, but also the current route (the top-most
/// route), then [isCurrent] will also be true. If it is the first route (the
/// bottom-most route), then [isFirst] will also be true.
///
/// If a higher route is entirely opaque, then the route will be active but not
/// rendered. It is even possible for the route to be active but for the stateful
/// widgets within the route to not be instantiated. See [ModalRoute.maintainState].
bool get isActive {
if (_navigator == null)
return false;
return _navigator._history.firstWhere(
_RouteEntry.isRoutePredicate(this),
orElse: () => null,
)?.isPresent == true;
}
}
/// Data that might be useful in constructing a [Route].
@immutable
class RouteSettings {
/// Creates data used to construct routes.
const RouteSettings({
this.name,
this.arguments,
});
/// Creates a copy of this route settings object with the given fields
/// replaced with the new values.
RouteSettings copyWith({
String name,
Object arguments,
}) {
return RouteSettings(
name: name ?? this.name,
arguments: arguments ?? this.arguments,
);
}
/// The name of the route (e.g., "/settings").
///
/// If null, the route is anonymous.
final String name;
/// The arguments passed to this route.
///
/// May be used when building the route, e.g. in [Navigator.onGenerateRoute].
final Object arguments;
@override
String toString() => '${objectRuntimeType(this, 'RouteSettings')}("$name", $arguments)';
}
/// Describes the configuration of a [Route].
///
/// The type argument `T` is the corresponding [Route]'s return type, as
/// used by [Route.currentResult], [Route.popped], and [Route.didPop].
///
/// See also:
///
/// * [Navigator.pages], which accepts a list of [Page]s and updates its routes
/// history.
abstract class Page<T> extends RouteSettings {
/// Creates a page and initializes [key] for subclasses.
///
/// The [arguments] argument must not be null.
const Page({
this.key,
String name,
Object arguments,
}) : super(name: name, arguments: arguments);
/// The key associated with this page.
///
/// This key will be used for comparing pages in [canUpdate].
final LocalKey key;
/// Whether this page can be updated with the [other] page.
///
/// Two pages are consider updatable if they have same the [runtimeType] and
/// [key].
bool canUpdate(Page<dynamic> other) {
return other.runtimeType == runtimeType &&
other.key == key;
}
/// Creates the [Route] that corresponds to this page.
///
/// The created [Route] must have its [Route.settings] property set to this [Page].
@factory
Route<T> createRoute(BuildContext context);
@override
String toString() => '${objectRuntimeType(this, 'Page')}("$name", $key, $arguments)';
}
/// An interface for observing the behavior of a [Navigator].
class NavigatorObserver {
/// The navigator that the observer is observing, if any.
NavigatorState get navigator => _navigator;
NavigatorState _navigator;
/// The [Navigator] pushed `route`.
///
/// The route immediately below that one, and thus the previously active
/// route, is `previousRoute`.
void didPush(Route<dynamic> route, Route<dynamic> previousRoute) { }
/// The [Navigator] popped `route`.
///
/// The route immediately below that one, and thus the newly active
/// route, is `previousRoute`.
void didPop(Route<dynamic> route, Route<dynamic> previousRoute) { }
/// The [Navigator] removed `route`.
///
/// If only one route is being removed, then the route immediately below
/// that one, if any, is `previousRoute`.
///
/// If multiple routes are being removed, then the route below the
/// bottommost route being removed, if any, is `previousRoute`, and this
/// method will be called once for each removed route, from the topmost route
/// to the bottommost route.
void didRemove(Route<dynamic> route, Route<dynamic> previousRoute) { }
/// The [Navigator] replaced `oldRoute` with `newRoute`.
void didReplace({ Route<dynamic> newRoute, Route<dynamic> oldRoute }) { }
/// The [Navigator]'s routes are being moved by a user gesture.
///
/// For example, this is called when an iOS back gesture starts, and is used
/// to disabled hero animations during such interactions.
void didStartUserGesture(Route<dynamic> route, Route<dynamic> previousRoute) { }
/// User gesture is no longer controlling the [Navigator].
///
/// Paired with an earlier call to [didStartUserGesture].
void didStopUserGesture() { }
}
/// An inherited widget to host a hero controller.
///
/// The hosted hero controller will be picked up by the navigator in the
/// [child] subtree. Once a navigator picks up this controller, the navigator
/// will bar any navigator below its subtree from receiving this controller.
///
/// The hero controller inside the [HeroControllerScope] can only subscribe to
/// one navigator at a time. An assertion will be thrown if the hero controller
/// subscribes to more than one navigators. This can happen when there are
/// multiple navigators under the same [HeroControllerScope] in parallel.
class HeroControllerScope extends InheritedWidget {
/// Creates a widget to host the input [controller].
const HeroControllerScope({
Key key,
this.controller,
Widget child,
}) : assert(controller != null),
super(key: key, child: child);
/// Creates a widget to prevent the subtree from receiving the hero controller
/// above.
const HeroControllerScope.none({
Key key,
Widget child,
}) : controller = null,
super(key: key, child: child);
/// The hero controller that is hosted inside this widget.
final HeroController controller;
/// Retrieves the [HeroController] from the closest [HeroControllerScope]
/// ancestor.
static HeroController of(BuildContext context) {
final HeroControllerScope host = context.dependOnInheritedWidgetOfExactType<HeroControllerScope>();
return host?.controller;
}
@override
bool updateShouldNotify(HeroControllerScope oldWidget) {
return oldWidget.controller != controller;
}
}
/// A [Route] wrapper interface that can be staged for [TransitionDelegate] to
/// decide how its underlying [Route] should transition on or off screen.
abstract class RouteTransitionRecord {
/// Retrieves the wrapped [Route].
Route<dynamic> get route;
/// Whether this route is waiting for the decision on how to enter the screen.
///
/// If this property is true, this route requires an explicit decision on how
/// to transition into the screen. Such a decision should be made in the
/// [TransitionDelegate.resolve].
bool get isWaitingForEnteringDecision;
/// Whether this route is waiting for the decision on how to exit the screen.
///
/// If this property is true, this route requires an explicit decision on how
/// to transition off the screen. Such a decision should be made in the
/// [TransitionDelegate.resolve].
bool get isWaitingForExitingDecision;
/// Marks the [route] to be pushed with transition.
///
/// During [TransitionDelegate.resolve], this can be called on an entering
/// route (where [RouteTransitionRecord.isWaitingForEnteringDecision] is true) in indicate that the
/// route should be pushed onto the [Navigator] with an animated transition.
void markForPush();
/// Marks the [route] to be added without transition.
///
/// During [TransitionDelegate.resolve], this can be called on an entering
/// route (where [RouteTransitionRecord.isWaitingForEnteringDecision] is true) in indicate that the
/// route should be added onto the [Navigator] without an animated transition.
void markForAdd();
/// Marks the [route] to be popped with transition.
///
/// During [TransitionDelegate.resolve], this can be called on an exiting
/// route to indicate that the route should be popped off the [Navigator] with
/// an animated transition.
void markForPop([dynamic result]);
/// Marks the [route] to be completed without transition.
///
/// During [TransitionDelegate.resolve], this can be called on an exiting
/// route to indicate that the route should be completed with the provided
/// result and removed from the [Navigator] without an animated transition.
void markForComplete([dynamic result]);
/// Marks the [route] to be removed without transition.
///
/// During [TransitionDelegate.resolve], this can be called on an exiting
/// route to indicate that the route should be removed from the [Navigator]
/// without completing and without an animated transition.
void markForRemove();
}
/// The delegate that decides how pages added and removed from [Navigator.pages]
/// transition in or out of the screen.
///
/// This abstract class implements the API to be called by [Navigator] when it
/// requires explicit decisions on how the routes transition on or off the screen.
///
/// To make route transition decisions, subclass must implement [resolve].
///
/// {@tool sample --template=freeform}
/// The following example demonstrates how to implement a subclass that always
/// removes or adds routes without animated transitions and puts the removed
/// routes at the top of the list.
///
/// ```dart imports
/// import 'package:flutter/widgets.dart';
/// ```
///
/// ```dart
/// class NoAnimationTransitionDelegate extends TransitionDelegate<void> {
/// @override
/// Iterable<RouteTransitionRecord> resolve({
/// List<RouteTransitionRecord> newPageRouteHistory,
/// Map<RouteTransitionRecord, RouteTransitionRecord> locationToExitingPageRoute,
/// Map<RouteTransitionRecord, List<RouteTransitionRecord>> pageRouteToPagelessRoutes,
/// }) {
/// final List<RouteTransitionRecord> results = <RouteTransitionRecord>[];
///
/// for (final RouteTransitionRecord pageRoute in newPageRouteHistory) {
/// if (pageRoute.isWaitingForEnteringDecision) {
/// pageRoute.markForAdd();
/// }
/// results.add(pageRoute);
///
/// }
/// for (final RouteTransitionRecord exitingPageRoute in locationToExitingPageRoute.values) {
/// if (exitingPageRoute.isWaitingForExitingDecision) {
/// exitingPageRoute.markForRemove();
/// final List<RouteTransitionRecord> pagelessRoutes = pageRouteToPagelessRoutes[exitingPageRoute];
/// if (pagelessRoutes != null) {
/// for (final RouteTransitionRecord pagelessRoute in pagelessRoutes) {
/// pagelessRoute.markForRemove();
/// }
/// }
/// }
/// results.add(exitingPageRoute);
///
/// }
/// return results;
/// }
/// }
///
/// ```
/// {@end-tool}
///
/// See also:
///
/// * [Navigator.transitionDelegate], which uses this class to make route
/// transition decisions.
/// * [DefaultTransitionDelegate], which implements the default way to decide
/// how routes transition in or out of the screen.
abstract class TransitionDelegate<T> {
/// Creates a delegate and enables subclass to create a constant class.
const TransitionDelegate();
Iterable<RouteTransitionRecord> _transition({
List<RouteTransitionRecord> newPageRouteHistory,
Map<RouteTransitionRecord, RouteTransitionRecord> locationToExitingPageRoute,
Map<RouteTransitionRecord, List<RouteTransitionRecord>> pageRouteToPagelessRoutes,
}) {
final Iterable<RouteTransitionRecord> results = resolve(
newPageRouteHistory: newPageRouteHistory,
locationToExitingPageRoute: locationToExitingPageRoute,
pageRouteToPagelessRoutes: pageRouteToPagelessRoutes,
);
// Verifies the integrity after the decisions have been made.
//
// Here are the rules:
// - All the entering routes in newPageRouteHistory must either be pushed or
// added.
// - All the exiting routes in locationToExitingPageRoute must either be
// popped, completed or removed.
// - All the pageless routes that belong to exiting routes must either be
// popped, completed or removed.
// - All the entering routes in the result must preserve the same order as
// the entering routes in newPageRouteHistory, and the result must contain
// all exiting routes.
// ex:
//
// newPageRouteHistory = [A, B, C]
//
// locationToExitingPageRoute = {A -> D, C -> E}
//
// results = [A, B ,C ,D ,E] is valid
// results = [D, A, B ,C ,E] is also valid because exiting route can be
// inserted in any place
//
// results = [B, A, C ,D ,E] is invalid because B must be after A.
// results = [A, B, C ,E] is invalid because results must include D.
assert(() {
final List<RouteTransitionRecord> resultsToVerify = results.toList(growable: false);
final Set<RouteTransitionRecord> exitingPageRoutes = locationToExitingPageRoute.values.toSet();
// Firstly, verifies all exiting routes have been marked.
for (final RouteTransitionRecord exitingPageRoute in exitingPageRoutes) {
assert(!exitingPageRoute.isWaitingForExitingDecision);
if (pageRouteToPagelessRoutes.containsKey(exitingPageRoute)) {
for (final RouteTransitionRecord pagelessRoute in pageRouteToPagelessRoutes[exitingPageRoute]) {
assert(!pagelessRoute.isWaitingForExitingDecision);
}
}
}
// Secondly, verifies the order of results matches the newPageRouteHistory
// and contains all the exiting routes.
int indexOfNextRouteInNewHistory = 0;
for (final _RouteEntry routeEntry in resultsToVerify.cast<_RouteEntry>()) {
assert(routeEntry != null);
assert(!routeEntry.isWaitingForEnteringDecision && !routeEntry.isWaitingForExitingDecision);
if (
indexOfNextRouteInNewHistory >= newPageRouteHistory.length ||
routeEntry != newPageRouteHistory[indexOfNextRouteInNewHistory]
) {
assert(exitingPageRoutes.contains(routeEntry));
exitingPageRoutes.remove(routeEntry);
} else {
indexOfNextRouteInNewHistory += 1;
}
}
assert(
indexOfNextRouteInNewHistory == newPageRouteHistory.length &&
exitingPageRoutes.isEmpty,
'The merged result from the $runtimeType.resolve does not include all '
'required routes. Do you remember to merge all exiting routes?'
);
return true;
}());
return results;
}
/// A method that will be called by the [Navigator] to decide how routes
/// transition in or out of the screen when [Navigator.pages] is updated.
///
/// The `newPageRouteHistory` list contains all page-based routes in the order
/// that will be on the [Navigator]'s history stack after this update
/// completes. If a route in `newPageRouteHistory` has its
/// [RouteTransitionRecord.isWaitingForEnteringDecision] set to true, this
/// route requires explicit decision on how it should transition onto the
/// Navigator. To make a decision, call [RouteTransitionRecord.markForPush] or
/// [RouteTransitionRecord.markForAdd].
///
/// The `locationToExitingPageRoute` contains the pages-based routes that
/// are removed from the routes history after page update. This map records
/// page-based routes to be removed with the location of the route in the
/// original route history before the update. The keys are the locations
/// represented by the page-based routes that are directly below the removed
/// routes, and the value are the page-based routes to be removed. The
/// location is null if the route to be removed is the bottom most route. If
/// a route in `locationToExitingPageRoute` has its
/// [RouteTransitionRecord.isWaitingForExitingDecision] set to true, this
/// route requires explicit decision on how it should transition off the
/// Navigator. To make a decision for a removed route, call
/// [RouteTransitionRecord.markForPop],
/// [RouteTransitionRecord.markForComplete] or
/// [RouteTransitionRecord.markForRemove]. It is possible that decisions are
/// not required for routes in the `locationToExitingPageRoute`. This can
/// happen if the routes have already been popped in earlier page updates and
/// are still waiting for popping animations to finish. In such case, those
/// routes are still included in the `locationToExitingPageRoute` with their
/// [RouteTransitionRecord.isWaitingForExitingDecision] set to false and no
/// decisions are required.
///
/// The `pageRouteToPagelessRoutes` records the page-based routes and their
/// associated pageless routes. If a page-based route is waiting for exiting
/// decision, its associated pageless routes also require explicit decisions
/// on how to transition off the screen.
///
/// Once all the decisions have been made, this method must merge the removed
/// routes (whether or not they require decisions) and the
/// `newPageRouteHistory` and return the merged result. The order in the
/// result will be the order the [Navigator] uses for updating the route
/// history. The return list must preserve the same order of routes in
/// `newPageRouteHistory`. The removed routes, however, can be inserted into
/// the return list freely as long as all of them are included.
///
/// For example, consider the following case.
///
/// newPageRouteHistory = [A, B, C]
///
/// locationToExitingPageRoute = {A -> D, C -> E}
///
/// The following outputs are valid.
///
/// result = [A, B ,C ,D ,E] is valid.
/// result = [D, A, B ,C ,E] is also valid because exiting route can be
/// inserted in any place.
///
/// The following outputs are invalid.
///
/// result = [B, A, C ,D ,E] is invalid because B must be after A.
/// result = [A, B, C ,E] is invalid because results must include D.
///
/// See also:
///
/// * [RouteTransitionRecord.markForPush], which makes route enter the screen
/// with an animated transition.
/// * [RouteTransitionRecord.markForAdd], which makes route enter the screen
/// without an animated transition.
/// * [RouteTransitionRecord.markForPop], which makes route exit the screen
/// with an animated transition.
/// * [RouteTransitionRecord.markForRemove], which does not complete the
/// route and makes it exit the screen without an animated transition.
/// * [RouteTransitionRecord.markForComplete], which completes the route and
/// makes it exit the screen without an animated transition.
/// * [DefaultTransitionDelegate.resolve], which implements the default way
/// to decide how routes transition in or out of the screen.
Iterable<RouteTransitionRecord> resolve({
List<RouteTransitionRecord> newPageRouteHistory,
Map<RouteTransitionRecord, RouteTransitionRecord> locationToExitingPageRoute,
Map<RouteTransitionRecord, List<RouteTransitionRecord>> pageRouteToPagelessRoutes,
});
}
/// The default implementation of [TransitionDelegate] that the [Navigator] will
/// use if its [Navigator.transitionDelegate] is not specified.
///
/// This transition delegate follows two rules. Firstly, all the entering routes
/// are placed on top of the exiting routes if they are at the same location.
/// Secondly, the top most route will always transition with an animated transition.
/// All the other routes below will either be completed with
/// [Route.currentResult] or added without an animated transition.
class DefaultTransitionDelegate<T> extends TransitionDelegate<T> {
/// Creates a default transition delegate.
const DefaultTransitionDelegate() : super();
@override
Iterable<RouteTransitionRecord> resolve({
List<RouteTransitionRecord> newPageRouteHistory,
Map<RouteTransitionRecord, RouteTransitionRecord> locationToExitingPageRoute,
Map<RouteTransitionRecord, List<RouteTransitionRecord>> pageRouteToPagelessRoutes,
}) {
final List<RouteTransitionRecord> results = <RouteTransitionRecord>[];
// This method will handle the exiting route and its corresponding pageless
// route at this location. It will also recursively check if there is any
// other exiting routes above it and handle them accordingly.
void handleExitingRoute(RouteTransitionRecord location, bool isLast) {
final RouteTransitionRecord exitingPageRoute = locationToExitingPageRoute[location];
if (exitingPageRoute == null)
return;
if (exitingPageRoute.isWaitingForExitingDecision) {
final bool hasPagelessRoute = pageRouteToPagelessRoutes.containsKey(exitingPageRoute);
final bool isLastExitingPageRoute = isLast && !locationToExitingPageRoute.containsKey(exitingPageRoute);
if (isLastExitingPageRoute && !hasPagelessRoute) {
exitingPageRoute.markForPop(exitingPageRoute.route.currentResult);
} else {
exitingPageRoute.markForComplete(exitingPageRoute.route.currentResult);
}
if (hasPagelessRoute) {
final List<RouteTransitionRecord> pagelessRoutes = pageRouteToPagelessRoutes[exitingPageRoute];
for (final RouteTransitionRecord pagelessRoute in pagelessRoutes) {
assert(pagelessRoute.isWaitingForExitingDecision);
if (isLastExitingPageRoute && pagelessRoute == pagelessRoutes.last) {
pagelessRoute.markForPop(pagelessRoute.route.currentResult);
} else {
pagelessRoute.markForComplete(pagelessRoute.route.currentResult);
}
}
}
}
results.add(exitingPageRoute);
// It is possible there is another exiting route above this exitingPageRoute.
handleExitingRoute(exitingPageRoute, isLast);
}
// Handles exiting route in the beginning of list.
handleExitingRoute(null, newPageRouteHistory.isEmpty);
for (final RouteTransitionRecord pageRoute in newPageRouteHistory) {
final bool isLastIteration = newPageRouteHistory.last == pageRoute;
if (pageRoute.isWaitingForEnteringDecision) {
if (!locationToExitingPageRoute.containsKey(pageRoute) && isLastIteration) {
pageRoute.markForPush();
} else {
pageRoute.markForAdd();
}
}
results.add(pageRoute);
handleExitingRoute(pageRoute, isLastIteration);
}
return results;
}
}
/// A widget that manages a set of child widgets with a stack discipline.
///
/// Many apps have a navigator near the top of their widget hierarchy in order
/// to display their logical history using an [Overlay] with the most recently
/// visited pages visually on top of the older pages. Using this pattern lets
/// the navigator visually transition from one page to another by moving the widgets
/// around in the overlay. Similarly, the navigator can be used to show a dialog
/// by positioning the dialog widget above the current page.
///
/// ## Using the Navigator API
///
/// Mobile apps typically reveal their contents via full-screen elements
/// called "screens" or "pages". In Flutter these elements are called
/// routes and they're managed by a [Navigator] widget. The navigator
/// manages a stack of [Route] objects and provides two ways for managing
/// the stack, the declarative API [Navigator.pages] or imperative API
/// [Navigator.push] and [Navigator.pop].
///
/// When your user interface fits this paradigm of a stack, where the user
/// should be able to _navigate_ back to an earlier element in the stack,
/// the use of routes and the Navigator is appropriate. On certain platforms,
/// such as Android, the system UI will provide a back button (outside the
/// bounds of your application) that will allow the user to navigate back
/// to earlier routes in your application's stack. On platforms that don't
/// have this build-in navigation mechanism, the use of an [AppBar] (typically
/// used in the [Scaffold.appBar] property) can automatically add a back
/// button for user navigation.
///
/// ## Using the Pages API
///
/// The [Navigator] will convert its [Navigator.pages] into a stack of [Route]s
/// if it is provided. A change in [Navigator.pages] will trigger an update to
/// the stack of [Route]s. The [Navigator] will update its routes to match the
/// new configuration of its [Navigator.pages]. To use this API, one can create
/// a [Page] subclass and defines a list of [Page]s for [Navigator.pages]. A
/// [Navigator.onPopPage] callback is also required to properly clean up the
/// input pages in case of a pop.
///
/// By Default, the [Navigator] will use [DefaultTransitionDelegate] to decide
/// how routes transition in or out of the screen. To customize it, define a
/// [TransitionDelegate] subclass and provide it to the
/// [Navigator.transitionDelegate].
///
/// ### Displaying a full-screen route
///
/// Although you can create a navigator directly, it's most common to use the
/// navigator created by the `Router` which itself is created and configured by
/// a [WidgetsApp] or a [MaterialApp] widget. You can refer to that navigator
/// with [Navigator.of].
///
/// A [MaterialApp] is the simplest way to set things up. The [MaterialApp]'s
/// home becomes the route at the bottom of the [Navigator]'s stack. It is what
/// you see when the app is launched.
///
/// ```dart
/// void main() {
/// runApp(MaterialApp(home: MyAppHome()));
/// }
/// ```
///
/// To push a new route on the stack you can create an instance of
/// [MaterialPageRoute] with a builder function that creates whatever you
/// want to appear on the screen. For example:
///
/// ```dart
/// Navigator.push(context, MaterialPageRoute<void>(
/// builder: (BuildContext context) {
/// return Scaffold(
/// appBar: AppBar(title: Text('My Page')),
/// body: Center(
/// child: TextButton(
/// child: Text('POP'),
/// onPressed: () {
/// Navigator.pop(context);
/// },
/// ),
/// ),
/// );
/// },
/// ));
/// ```
///
/// The route defines its widget with a builder function instead of a
/// child widget because it will be built and rebuilt in different
/// contexts depending on when it's pushed and popped.
///
/// As you can see, the new route can be popped, revealing the app's home
/// page, with the Navigator's pop method:
///
/// ```dart
/// Navigator.pop(context);
/// ```
///
/// It usually isn't necessary to provide a widget that pops the Navigator
/// in a route with a [Scaffold] because the Scaffold automatically adds a
/// 'back' button to its AppBar. Pressing the back button causes
/// [Navigator.pop] to be called. On Android, pressing the system back
/// button does the same thing.
///
/// ### Using named navigator routes
///
/// Mobile apps often manage a large number of routes and it's often
/// easiest to refer to them by name. Route names, by convention,
/// use a path-like structure (for example, '/a/b/c').
/// The app's home page route is named '/' by default.
///
/// The [MaterialApp] can be created
/// with a [Map<String, WidgetBuilder>] which maps from a route's name to
/// a builder function that will create it. The [MaterialApp] uses this
/// map to create a value for its navigator's [onGenerateRoute] callback.
///
/// ```dart
/// void main() {
/// runApp(MaterialApp(
/// home: MyAppHome(), // becomes the route named '/'
/// routes: <String, WidgetBuilder> {
/// '/a': (BuildContext context) => MyPage(title: 'page A'),
/// '/b': (BuildContext context) => MyPage(title: 'page B'),
/// '/c': (BuildContext context) => MyPage(title: 'page C'),
/// },
/// ));
/// }
/// ```
///
/// To show a route by name:
///
/// ```dart
/// Navigator.pushNamed(context, '/b');
/// ```
///
/// ### Routes can return a value
///
/// When a route is pushed to ask the user for a value, the value can be
/// returned via the [pop] method's result parameter.
///
/// Methods that push a route return a [Future]. The Future resolves when the
/// route is popped and the [Future]'s value is the [pop] method's `result`
/// parameter.
///
/// For example if we wanted to ask the user to press 'OK' to confirm an
/// operation we could `await` the result of [Navigator.push]:
///
/// ```dart
/// bool value = await Navigator.push(context, MaterialPageRoute<bool>(
/// builder: (BuildContext context) {
/// return Center(
/// child: GestureDetector(
/// child: Text('OK'),
/// onTap: () { Navigator.pop(context, true); }
/// ),
/// );
/// }
/// ));
/// ```
///
/// If the user presses 'OK' then value will be true. If the user backs
/// out of the route, for example by pressing the Scaffold's back button,
/// the value will be null.
///
/// When a route is used to return a value, the route's type parameter must
/// match the type of [pop]'s result. That's why we've used
/// `MaterialPageRoute<bool>` instead of `MaterialPageRoute<void>` or just
/// `MaterialPageRoute`. (If you prefer to not specify the types, though, that's
/// fine too.)
///
/// ### Popup routes
///
/// Routes don't have to obscure the entire screen. [PopupRoute]s cover the
/// screen with a [ModalRoute.barrierColor] that can be only partially opaque to
/// allow the current screen to show through. Popup routes are "modal" because
/// they block input to the widgets below.
///
/// There are functions which create and show popup routes. For
/// example: [showDialog], [showMenu], and [showModalBottomSheet]. These
/// functions return their pushed route's Future as described above.
/// Callers can await the returned value to take an action when the
/// route is popped, or to discover the route's value.
///
/// There are also widgets which create popup routes, like [PopupMenuButton] and
/// [DropdownButton]. These widgets create internal subclasses of PopupRoute
/// and use the Navigator's push and pop methods to show and dismiss them.
///
/// ### Custom routes
///
/// You can create your own subclass of one of the widget library route classes
/// like [PopupRoute], [ModalRoute], or [PageRoute], to control the animated
/// transition employed to show the route, the color and behavior of the route's
/// modal barrier, and other aspects of the route.
///
/// The [PageRouteBuilder] class makes it possible to define a custom route
/// in terms of callbacks. Here's an example that rotates and fades its child
/// when the route appears or disappears. This route does not obscure the entire
/// screen because it specifies `opaque: false`, just as a popup route does.
///
/// ```dart
/// Navigator.push(context, PageRouteBuilder(
/// opaque: false,
/// pageBuilder: (BuildContext context, _, __) {
/// return Center(child: Text('My PageRoute'));
/// },
/// transitionsBuilder: (___, Animation<double> animation, ____, Widget child) {
/// return FadeTransition(
/// opacity: animation,
/// child: RotationTransition(
/// turns: Tween<double>(begin: 0.5, end: 1.0).animate(animation),
/// child: child,
/// ),
/// );
/// }
/// ));
/// ```
///
/// The page route is built in two parts, the "page" and the
/// "transitions". The page becomes a descendant of the child passed to
/// the `transitionsBuilder` function. Typically the page is only built once,
/// because it doesn't depend on its animation parameters (elided with `_`
/// and `__` in this example). The transition is built on every frame
/// for its duration.
///
/// ### Nesting Navigators
///
/// An app can use more than one [Navigator]. Nesting one [Navigator] below
/// another [Navigator] can be used to create an "inner journey" such as tabbed
/// navigation, user registration, store checkout, or other independent journeys
/// that represent a subsection of your overall application.
///
/// #### Example
///
/// It is standard practice for iOS apps to use tabbed navigation where each
/// tab maintains its own navigation history. Therefore, each tab has its own
/// [Navigator], creating a kind of "parallel navigation."
///
/// In addition to the parallel navigation of the tabs, it is still possible to
/// launch full-screen pages that completely cover the tabs. For example: an
/// on-boarding flow, or an alert dialog. Therefore, there must exist a "root"
/// [Navigator] that sits above the tab navigation. As a result, each of the
/// tab's [Navigator]s are actually nested [Navigator]s sitting below a single
/// root [Navigator].
///
/// In practice, the nested [Navigator]s for tabbed navigation sit in the
/// [WidgetsApp] and [CupertinoTabView] widgets and do not need to be explicitly
/// created or managed.
///
/// {@tool sample --template=freeform}
/// The following example demonstrates how a nested [Navigator] can be used to
/// present a standalone user registration journey.
///
/// Even though this example uses two [Navigator]s to demonstrate nested
/// [Navigator]s, a similar result is possible using only a single [Navigator].
///
/// Run this example with `flutter run --route=/signup` to start it with
/// the signup flow instead of on the home page.
///
/// ```dart imports
/// import 'package:flutter/material.dart';
/// ```
///
/// ```dart main
/// void main() => runApp(MyApp());
/// ```
///
/// ```dart
/// class MyApp extends StatelessWidget {
/// @override
/// Widget build(BuildContext context) {
/// return MaterialApp(
/// title: 'Flutter Code Sample for Navigator',
/// // MaterialApp contains our top-level Navigator
/// initialRoute: '/',
/// routes: {
/// '/': (BuildContext context) => HomePage(),
/// '/signup': (BuildContext context) => SignUpPage(),
/// },
/// );
/// }
/// }
///
/// class HomePage extends StatelessWidget {
/// @override
/// Widget build(BuildContext context) {
/// return DefaultTextStyle(
/// style: Theme.of(context).textTheme.headline4,
/// child: Container(
/// color: Colors.white,
/// alignment: Alignment.center,
/// child: Text('Home Page'),
/// ),
/// );
/// }
/// }
///
/// class CollectPersonalInfoPage extends StatelessWidget {
/// @override
/// Widget build(BuildContext context) {
/// return DefaultTextStyle(
/// style: Theme.of(context).textTheme.headline4,
/// child: GestureDetector(
/// onTap: () {
/// // This moves from the personal info page to the credentials page,
/// // replacing this page with that one.
/// Navigator.of(context)
/// .pushReplacementNamed('signup/choose_credentials');
/// },
/// child: Container(
/// color: Colors.lightBlue,
/// alignment: Alignment.center,
/// child: Text('Collect Personal Info Page'),
/// ),
/// ),
/// );
/// }
/// }
///
/// class ChooseCredentialsPage extends StatelessWidget {
/// const ChooseCredentialsPage({
/// this.onSignupComplete,
/// });
///
/// final VoidCallback onSignupComplete;
///
/// @override
/// Widget build(BuildContext context) {
/// return GestureDetector(
/// onTap: onSignupComplete,
/// child: DefaultTextStyle(
/// style: Theme.of(context).textTheme.headline4,
/// child: Container(
/// color: Colors.pinkAccent,
/// alignment: Alignment.center,
/// child: Text('Choose Credentials Page'),
/// ),
/// ),
/// );
/// }
/// }
///
/// class SignUpPage extends StatelessWidget {
/// @override
/// Widget build(BuildContext context) {
/// // SignUpPage builds its own Navigator which ends up being a nested
/// // Navigator in our app.
/// return Navigator(
/// initialRoute: 'signup/personal_info',
/// onGenerateRoute: (RouteSettings settings) {
/// WidgetBuilder builder;
/// switch (settings.name) {
/// case 'signup/personal_info':
/// // Assume CollectPersonalInfoPage collects personal info and then
/// // navigates to 'signup/choose_credentials'.
/// builder = (BuildContext _) => CollectPersonalInfoPage();
/// break;
/// case 'signup/choose_credentials':
/// // Assume ChooseCredentialsPage collects new credentials and then
/// // invokes 'onSignupComplete()'.
/// builder = (BuildContext _) => ChooseCredentialsPage(
/// onSignupComplete: () {
/// // Referencing Navigator.of(context) from here refers to the
/// // top level Navigator because SignUpPage is above the
/// // nested Navigator that it created. Therefore, this pop()
/// // will pop the entire "sign up" journey and return to the
/// // "/" route, AKA HomePage.
/// Navigator.of(context).pop();
/// },
/// );
/// break;
/// default:
/// throw Exception('Invalid route: ${settings.name}');
/// }
/// return MaterialPageRoute(builder: builder, settings: settings);
/// },
/// );
/// }
/// }
/// ```
/// {@end-tool}
///
/// [Navigator.of] operates on the nearest ancestor [Navigator] from the given
/// [BuildContext]. Be sure to provide a [BuildContext] below the intended
/// [Navigator], especially in large `build` methods where nested [Navigator]s
/// are created. The [Builder] widget can be used to access a [BuildContext] at
/// a desired location in the widget subtree.
class Navigator extends StatefulWidget {
/// Creates a widget that maintains a stack-based history of child widgets.
///
/// The [onGenerateRoute], [pages], [onGenerateInitialRoutes],
/// [transitionDelegate], [observers] arguments must not be null.
///
/// If the [pages] is not empty, the [onPopPage] must not be null.
const Navigator({
Key key,
this.pages = const <Page<dynamic>>[],
this.onPopPage,
this.initialRoute,
this.onGenerateInitialRoutes = Navigator.defaultGenerateInitialRoutes,
this.onGenerateRoute,
this.onUnknownRoute,
this.transitionDelegate = const DefaultTransitionDelegate<dynamic>(),
this.reportsRouteUpdateToEngine = false,
this.observers = const <NavigatorObserver>[],
}) : assert(pages != null),
assert(onGenerateInitialRoutes != null),
assert(transitionDelegate != null),
assert(observers != null),
assert(reportsRouteUpdateToEngine != null),
super(key: key);
/// The list of pages with which to populate the history.
///
/// Pages are turned into routes using [Page.createRoute] in a manner
/// analogous to how [Widget]s are turned into [Element]s (and [State]s or
/// [RenderObject]s) using [Widget.createElement] (and
/// [StatefulWidget.createState] or [RenderObjectWidget.createRenderObject]).
///
/// When this list is updated, the new list is compared to the previous
/// list and the set of routes is updated accordingly.
///
/// Some [Route]s do not correspond to [Page] objects, namely, those that are
/// added to the history using the [Navigator] API ([push] and friends). A
/// [Route] that does not correspond to a [Page] object is called a pageless
/// route and is tied to the [Route] that _does_ correspond to a [Page] object
/// that is below it in the history.
///
/// Pages that are added or removed may be animated as controlled by the
/// [transitionDelegate]. If a page is removed that had other pageless routes
/// pushed on top of it using [push] and friends, those pageless routes are
/// also removed with or without animation as determined by the
/// [transitionDelegate].
///
/// To use this API, an [onPopPage] callback must also be provided to properly
/// clean up this list if a page has been popped.
///
/// If [initialRoute] is non-null when the widget is first created, then
/// [onGenerateInitialRoutes] is used to generate routes that are above those
/// corresponding to [pages] in the initial history.
final List<Page<dynamic>> pages;
/// Called when [pop] is invoked but the current [Route] corresponds to a
/// [Page] found in the [pages] list.
///
/// The `result` argument is the value with which the route is to complete
/// (e.g. the value returned from a dialog).
///
/// This callback is responsible for calling [Route.didPop] and returning
/// whether this pop is successful.
///
/// The [Navigator] widget should be rebuilt with a [pages] list that does not
/// contain the [Page] for the given [Route]. The next time the [pages] list
/// is updated, if the [Page] corresponding to this [Route] is still present,
/// it will be interpreted as a new route to display.
final PopPageCallback onPopPage;
/// The delegate used for deciding how routes transition in or off the screen
/// during the [pages] updates.
///
/// Defaults to [DefaultTransitionDelegate] if not specified, cannot be null.
final TransitionDelegate<dynamic> transitionDelegate;
/// The name of the first route to show.
///
/// Defaults to [Navigator.defaultRouteName].
///
/// The value is interpreted according to [onGenerateInitialRoutes], which
/// defaults to [defaultGenerateInitialRoutes].
final String initialRoute;
/// Called to generate a route for a given [RouteSettings].
final RouteFactory onGenerateRoute;
/// Called when [onGenerateRoute] fails to generate a route.
///
/// This callback is typically used for error handling. For example, this
/// callback might always generate a "not found" page that describes the route
/// that wasn't found.
///
/// Unknown routes can arise either from errors in the app or from external
/// requests to push routes, such as from Android intents.
final RouteFactory onUnknownRoute;
/// A list of observers for this navigator.
final List<NavigatorObserver> observers;
/// The name for the default route of the application.
///
/// See also:
///
/// * [dart:ui.Window.defaultRouteName], which reflects the route that the
/// application was started with.
static const String defaultRouteName = '/';
/// Called when the widget is created to generate the initial list of [Route]
/// objects if [initialRoute] is not null.
///
/// Defaults to [defaultGenerateInitialRoutes].
///
/// The [NavigatorState] and [initialRoute] will be passed to the callback.
/// The callback must return a list of [Route] objects with which the history
/// will be primed.
final RouteListFactory onGenerateInitialRoutes;
/// Whether this navigator should report route update message back to the
/// engine when the top-most route changes.
///
/// If the property is set to true, this navigator automatically sends the
/// route update message to the engine when it detects top-most route changes.
/// The messages are used by the web engine to update the browser URL bar.
///
/// If there are multiple navigators in the widget tree, at most one of them
/// can set this property to true (typically, the top-most one created from
/// the [WidgetsApp]). Otherwise, the web engine may receive multiple route
/// update messages from different navigators and fail to update the URL
/// bar.
///
/// Defaults to false.
final bool reportsRouteUpdateToEngine;
/// Push a named route onto the navigator that most tightly encloses the given
/// context.
///
/// {@template flutter.widgets.navigator.pushNamed}
/// The route name will be passed to the [Navigator.onGenerateRoute]
/// callback. The returned route will be pushed into the navigator.
///
/// The new route and the previous route (if any) are notified (see
/// [Route.didPush] and [Route.didChangeNext]). If the [Navigator] has any
/// [Navigator.observers], they will be notified as well (see
/// [NavigatorObserver.didPush]).
///
/// Ongoing gestures within the current route are canceled when a new route is
/// pushed.
///
/// Returns a [Future] that completes to the `result` value passed to [pop]
/// when the pushed route is popped off the navigator.
///
/// The `T` type argument is the type of the return value of the route.
///
/// To use [pushNamed], an [Navigator.onGenerateRoute] callback must be
/// provided,
/// {@endtemplate}
///
/// {@template flutter.widgets.navigator.pushNamed.arguments}
/// The provided `arguments` are passed to the pushed route via
/// [RouteSettings.arguments]. Any object can be passed as `arguments` (e.g. a
/// [String], [int], or an instance of a custom `MyRouteArguments` class).
/// Often, a [Map] is used to pass key-value pairs.
///
/// The `arguments` may be used in [Navigator.onGenerateRoute] or
/// [Navigator.onUnknownRoute] to construct the route.
/// {@endtemplate}
///
/// {@tool snippet}
///
/// Typical usage is as follows:
///
/// ```dart
/// void _didPushButton() {
/// Navigator.pushNamed(context, '/settings');
/// }
/// ```
/// {@end-tool}
///
/// {@tool snippet}
///
/// The following example shows how to pass additional `arguments` to the
/// route:
///
/// ```dart
/// void _showBerlinWeather() {
/// Navigator.pushNamed(
/// context,
/// '/weather',
/// arguments: <String, String>{
/// 'city': 'Berlin',
/// 'country': 'Germany',
/// },
/// );
/// }
/// ```
/// {@end-tool}
///
/// {@tool snippet}
///
/// The following example shows how to pass a custom Object to the route:
///
/// ```dart
/// class WeatherRouteArguments {
/// WeatherRouteArguments({ this.city, this.country });
/// final String city;
/// final String country;
///
/// bool get isGermanCapital {
/// return country == 'Germany' && city == 'Berlin';
/// }
/// }
///
/// void _showWeather() {
/// Navigator.pushNamed(
/// context,
/// '/weather',
/// arguments: WeatherRouteArguments(city: 'Berlin', country: 'Germany'),
/// );
/// }
/// ```
/// {@end-tool}
@optionalTypeArgs
static Future<T> pushNamed<T extends Object>(
BuildContext context,
String routeName, {
Object arguments,
}) {
return Navigator.of(context).pushNamed<T>(routeName, arguments: arguments);
}
/// Replace the current route of the navigator that most tightly encloses the
/// given context by pushing the route named [routeName] and then disposing
/// the previous route once the new route has finished animating in.
///
/// {@template flutter.widgets.navigator.pushReplacementNamed}
/// If non-null, `result` will be used as the result of the route that is
/// removed; the future that had been returned from pushing that old route
/// will complete with `result`. Routes such as dialogs or popup menus
/// typically use this mechanism to return the value selected by the user to
/// the widget that created their route. The type of `result`, if provided,
/// must match the type argument of the class of the old route (`TO`).
///
/// The route name will be passed to the [Navigator.onGenerateRoute]
/// callback. The returned route will be pushed into the navigator.
///
/// The new route and the route below the removed route are notified (see
/// [Route.didPush] and [Route.didChangeNext]). If the [Navigator] has any
/// [Navigator.observers], they will be notified as well (see
/// [NavigatorObserver.didReplace]). The removed route is notified once the
/// new route has finished animating (see [Route.didComplete]). The removed
/// route's exit animation is not run (see [popAndPushNamed] for a variant
/// that does animated the removed route).
///
/// Ongoing gestures within the current route are canceled when a new route is
/// pushed.
///
/// Returns a [Future] that completes to the `result` value passed to [pop]
/// when the pushed route is popped off the navigator.
///
/// The `T` type argument is the type of the return value of the new route,
/// and `TO` is the type of the return value of the old route.
///
/// To use [pushReplacementNamed], a [Navigator.onGenerateRoute] callback must
/// be provided.
/// {@endtemplate}
///
/// {@macro flutter.widgets.navigator.pushNamed.arguments}
///
/// {@tool snippet}
///
/// Typical usage is as follows:
///
/// ```dart
/// void _switchToBrightness() {
/// Navigator.pushReplacementNamed(context, '/settings/brightness');
/// }
/// ```
/// {@end-tool}
@optionalTypeArgs
static Future<T> pushReplacementNamed<T extends Object, TO extends Object>(
BuildContext context,
String routeName, {
TO result,
Object arguments,
}) {
return Navigator.of(context).pushReplacementNamed<T, TO>(routeName, arguments: arguments, result: result);
}
/// Pop the current route off the navigator that most tightly encloses the
/// given context and push a named route in its place.
///
/// {@template flutter.widgets.navigator.popAndPushNamed}
/// The popping of the previous route is handled as per [pop].
///
/// The new route's name will be passed to the [Navigator.onGenerateRoute]
/// callback. The returned route will be pushed into the navigator.
///
/// The new route, the old route, and the route below the old route (if any)
/// are all notified (see [Route.didPop], [Route.didComplete],
/// [Route.didPopNext], [Route.didPush], and [Route.didChangeNext]). If the
/// [Navigator] has any [Navigator.observers], they will be notified as well
/// (see [NavigatorObserver.didPop] and [NavigatorObserver.didPush]). The
/// animations for the pop and the push are performed simultaneously, so the
/// route below may be briefly visible even if both the old route and the new
/// route are opaque (see [TransitionRoute.opaque]).
///
/// Ongoing gestures within the current route are canceled when a new route is
/// pushed.
///
/// Returns a [Future] that completes to the `result` value passed to [pop]
/// when the pushed route is popped off the navigator.
///
/// The `T` type argument is the type of the return value of the new route,
/// and `TO` is the return value type of the old route.
///
/// To use [popAndPushNamed], a [Navigator.onGenerateRoute] callback must be provided.
///
/// {@endtemplate}
///
/// {@macro flutter.widgets.navigator.pushNamed.arguments}
///
/// {@tool snippet}
///
/// Typical usage is as follows:
///
/// ```dart
/// void _selectAccessibility() {
/// Navigator.popAndPushNamed(context, '/settings/accessibility');
/// }
/// ```
/// {@end-tool}
@optionalTypeArgs
static Future<T> popAndPushNamed<T extends Object, TO extends Object>(
BuildContext context,
String routeName, {
TO result,
Object arguments,
}) {
return Navigator.of(context).popAndPushNamed<T, TO>(routeName, arguments: arguments, result: result);
}
/// Push the route with the given name onto the navigator that most tightly
/// encloses the given context, and then remove all the previous routes until
/// the `predicate` returns true.
///
/// {@template flutter.widgets.navigator.pushNamedAndRemoveUntil}
/// The predicate may be applied to the same route more than once if
/// [Route.willHandlePopInternally] is true.
///
/// To remove routes until a route with a certain name, use the
/// [RoutePredicate] returned from [ModalRoute.withName].
///
/// To remove all the routes below the pushed route, use a [RoutePredicate]
/// that always returns false (e.g. `(Route<dynamic> route) => false`).
///
/// The removed routes are removed without being completed, so this method
/// does not take a return value argument.
///
/// The new route's name (`routeName`) will be passed to the
/// [Navigator.onGenerateRoute] callback. The returned route will be pushed
/// into the navigator.
///
/// The new route and the route below the bottommost removed route (which
/// becomes the route below the new route) are notified (see [Route.didPush]
/// and [Route.didChangeNext]). If the [Navigator] has any
/// [Navigator.observers], they will be notified as well (see
/// [NavigatorObserver.didPush] and [NavigatorObserver.didRemove]). The
/// removed routes are disposed, without being notified, once the new route
/// has finished animating. The futures that had been returned from pushing
/// those routes will not complete.
///
/// Ongoing gestures within the current route are canceled when a new route is
/// pushed.
///
/// Returns a [Future] that completes to the `result` value passed to [pop]
/// when the pushed route is popped off the navigator.
///
/// The `T` type argument is the type of the return value of the new route.
///
/// To use [pushNamedAndRemoveUntil], an [Navigator.onGenerateRoute] callback
/// must be provided.
/// {@endtemplate}
///
/// {@macro flutter.widgets.navigator.pushNamed.arguments}
///
/// {@tool snippet}
///
/// Typical usage is as follows:
///
/// ```dart
/// void _resetToCalendar() {
/// Navigator.pushNamedAndRemoveUntil(context, '/calendar', ModalRoute.withName('/'));
/// }
/// ```
/// {@end-tool}
@optionalTypeArgs
static Future<T> pushNamedAndRemoveUntil<T extends Object>(
BuildContext context,
String newRouteName,
RoutePredicate predicate, {
Object arguments,
}) {
return Navigator.of(context).pushNamedAndRemoveUntil<T>(newRouteName, predicate, arguments: arguments);
}
/// Push the given route onto the navigator that most tightly encloses the
/// given context.
///
/// {@template flutter.widgets.navigator.push}
/// The new route and the previous route (if any) are notified (see
/// [Route.didPush] and [Route.didChangeNext]). If the [Navigator] has any
/// [Navigator.observers], they will be notified as well (see
/// [NavigatorObserver.didPush]).
///
/// Ongoing gestures within the current route are canceled when a new route is
/// pushed.
///
/// Returns a [Future] that completes to the `result` value passed to [pop]
/// when the pushed route is popped off the navigator.
///
/// The `T` type argument is the type of the return value of the route.
/// {@endtemplate}
///
/// {@tool snippet}
///
/// Typical usage is as follows:
///
/// ```dart
/// void _openMyPage() {
/// Navigator.push(context, MaterialPageRoute(builder: (BuildContext context) => MyPage()));
/// }
/// ```
/// {@end-tool}
@optionalTypeArgs
static Future<T> push<T extends Object>(BuildContext context, Route<T> route) {
return Navigator.of(context).push(route);
}
/// Replace the current route of the navigator that most tightly encloses the
/// given context by pushing the given route and then disposing the previous
/// route once the new route has finished animating in.
///
/// {@template flutter.widgets.navigator.pushReplacement}
/// If non-null, `result` will be used as the result of the route that is
/// removed; the future that had been returned from pushing that old route will
/// complete with `result`. Routes such as dialogs or popup menus typically
/// use this mechanism to return the value selected by the user to the widget
/// that created their route. The type of `result`, if provided, must match
/// the type argument of the class of the old route (`TO`).
///
/// The new route and the route below the removed route are notified (see
/// [Route.didPush] and [Route.didChangeNext]). If the [Navigator] has any
/// [Navigator.observers], they will be notified as well (see
/// [NavigatorObserver.didReplace]). The removed route is notified once the
/// new route has finished animating (see [Route.didComplete]).
///
/// Ongoing gestures within the current route are canceled when a new route is
/// pushed.
///
/// Returns a [Future] that completes to the `result` value passed to [pop]
/// when the pushed route is popped off the navigator.
///
/// The `T` type argument is the type of the return value of the new route,
/// and `TO` is the type of the return value of the old route.
/// {@endtemplate}
///
/// {@tool snippet}
///
/// Typical usage is as follows:
///
/// ```dart
/// void _completeLogin() {
/// Navigator.pushReplacement(
/// context, MaterialPageRoute(builder: (BuildContext context) => MyHomePage()));
/// }
/// ```
/// {@end-tool}
@optionalTypeArgs
static Future<T> pushReplacement<T extends Object, TO extends Object>(BuildContext context, Route<T> newRoute, { TO result }) {
return Navigator.of(context).pushReplacement<T, TO>(newRoute, result: result);
}
/// Push the given route onto the navigator that most tightly encloses the
/// given context, and then remove all the previous routes until the
/// `predicate` returns true.
///
/// {@template flutter.widgets.navigator.pushAndRemoveUntil}
/// The predicate may be applied to the same route more than once if
/// [Route.willHandlePopInternally] is true.
///
/// To remove routes until a route with a certain name, use the
/// [RoutePredicate] returned from [ModalRoute.withName].
///
/// To remove all the routes below the pushed route, use a [RoutePredicate]
/// that always returns false (e.g. `(Route<dynamic> route) => false`).
///
/// The removed routes are removed without being completed, so this method
/// does not take a return value argument.
///
/// The newly pushed route and its preceding route are notified for
/// [Route.didPush]. After removal, the new route and its new preceding route,
/// (the route below the bottommost removed route) are notified through
/// [Route.didChangeNext]). If the [Navigator] has any [Navigator.observers],
/// they will be notified as well (see [NavigatorObserver.didPush] and
/// [NavigatorObserver.didRemove]). The removed routes are disposed of and
/// notified, once the new route has finished animating. The futures that had
/// been returned from pushing those routes will not complete.
///
/// Ongoing gestures within the current route are canceled when a new route is
/// pushed.
///
/// Returns a [Future] that completes to the `result` value passed to [pop]
/// when the pushed route is popped off the navigator.
///
/// The `T` type argument is the type of the return value of the new route.
/// {@endtemplate}
///
/// {@tool snippet}
///
/// Typical usage is as follows:
///
/// ```dart
/// void _finishAccountCreation() {
/// Navigator.pushAndRemoveUntil(
/// context,
/// MaterialPageRoute(builder: (BuildContext context) => MyHomePage()),
/// ModalRoute.withName('/'),
/// );
/// }
/// ```
/// {@end-tool}
@optionalTypeArgs
static Future<T> pushAndRemoveUntil<T extends Object>(BuildContext context, Route<T> newRoute, RoutePredicate predicate) {
return Navigator.of(context).pushAndRemoveUntil<T>(newRoute, predicate);
}
/// Replaces a route on the navigator that most tightly encloses the given
/// context with a new route.
///
/// {@template flutter.widgets.navigator.replace}
/// The old route must not be currently visible, as this method skips the
/// animations and therefore the removal would be jarring if it was visible.
/// To replace the top-most route, consider [pushReplacement] instead, which
/// _does_ animate the new route, and delays removing the old route until the
/// new route has finished animating.
///
/// The removed route is removed without being completed, so this method does
/// not take a return value argument.
///
/// The new route, the route below the new route (if any), and the route above
/// the new route, are all notified (see [Route.didReplace],
/// [Route.didChangeNext], and [Route.didChangePrevious]). If the [Navigator]
/// has any [Navigator.observers], they will be notified as well (see
/// [NavigatorObserver.didReplace]). The removed route is disposed without
/// being notified. The future that had been returned from pushing that routes
/// will not complete.
///
/// This can be useful in combination with [removeRouteBelow] when building a
/// non-linear user experience.
///
/// The `T` type argument is the type of the return value of the new route.
/// {@endtemplate}
///
/// See also:
///
/// * [replaceRouteBelow], which is the same but identifies the route to be
/// removed by reference to the route above it, rather than directly.
@optionalTypeArgs
static void replace<T extends Object>(BuildContext context, { @required Route<dynamic> oldRoute, @required Route<T> newRoute }) {
return Navigator.of(context).replace<T>(oldRoute: oldRoute, newRoute: newRoute);
}
/// Replaces a route on the navigator that most tightly encloses the given
/// context with a new route. The route to be replaced is the one below the
/// given `anchorRoute`.
///
/// {@template flutter.widgets.navigator.replaceRouteBelow}
/// The old route must not be current visible, as this method skips the
/// animations and therefore the removal would be jarring if it was visible.
/// To replace the top-most route, consider [pushReplacement] instead, which
/// _does_ animate the new route, and delays removing the old route until the
/// new route has finished animating.
///
/// The removed route is removed without being completed, so this method does
/// not take a return value argument.
///
/// The new route, the route below the new route (if any), and the route above
/// the new route, are all notified (see [Route.didReplace],
/// [Route.didChangeNext], and [Route.didChangePrevious]). If the [Navigator]
/// has any [Navigator.observers], they will be notified as well (see
/// [NavigatorObserver.didReplace]). The removed route is disposed without
/// being notified. The future that had been returned from pushing that routes
/// will not complete.
///
/// The `T` type argument is the type of the return value of the new route.
/// {@endtemplate}
///
/// See also:
///
/// * [replace], which is the same but identifies the route to be removed
/// directly.
@optionalTypeArgs
static void replaceRouteBelow<T extends Object>(BuildContext context, { @required Route<dynamic> anchorRoute, Route<T> newRoute }) {
return Navigator.of(context).replaceRouteBelow<T>(anchorRoute: anchorRoute, newRoute: newRoute);
}
/// Whether the navigator that most tightly encloses the given context can be
/// popped.
///
/// {@template flutter.widgets.navigator.canPop}
/// The initial route cannot be popped off the navigator, which implies that
/// this function returns true only if popping the navigator would not remove
/// the initial route.
///
/// If there is no [Navigator] in scope, returns false.
/// {@endtemplate}
///
/// See also:
///
/// * [Route.isFirst], which returns true for routes for which [canPop]
/// returns false.
static bool canPop(BuildContext context) {
final NavigatorState navigator = Navigator.of(context, nullOk: true);
return navigator != null && navigator.canPop();
}
/// Consults the current route's [Route.willPop] method, and acts accordingly,
/// potentially popping the route as a result; returns whether the pop request
/// should be considered handled.
///
/// {@template flutter.widgets.navigator.maybePop}
/// If [Route.willPop] returns [RoutePopDisposition.pop], then the [pop]
/// method is called, and this method returns true, indicating that it handled
/// the pop request.
///
/// If [Route.willPop] returns [RoutePopDisposition.doNotPop], then this
/// method returns true, but does not do anything beyond that.
///
/// If [Route.willPop] returns [RoutePopDisposition.bubble], then this method
/// returns false, and the caller is responsible for sending the request to
/// the containing scope (e.g. by closing the application).
///
/// This method is typically called for a user-initiated [pop]. For example on
/// Android it's called by the binding for the system's back button.
///
/// The `T` type argument is the type of the return value of the current
/// route. (Typically this isn't known; consider specifying `dynamic` or
/// `Null`.)
/// {@endtemplate}
///
/// See also:
///
/// * [Form], which provides an `onWillPop` callback that enables the form
/// to veto a [pop] initiated by the app's back button.
/// * [ModalRoute], which provides a `scopedWillPopCallback` that can be used
/// to define the route's `willPop` method.
@optionalTypeArgs
static Future<bool> maybePop<T extends Object>(BuildContext context, [ T result ]) {
return Navigator.of(context).maybePop<T>(result);
}
/// Pop the top-most route off the navigator that most tightly encloses the
/// given context.
///
/// {@template flutter.widgets.navigator.pop}
/// The current route's [Route.didPop] method is called first. If that method
/// returns false, then the route remains in the [Navigator]'s history (the
/// route is expected to have popped some internal state; see e.g.
/// [LocalHistoryRoute]). Otherwise, the rest of this description applies.
///
/// If non-null, `result` will be used as the result of the route that is
/// popped; the future that had been returned from pushing the popped route
/// will complete with `result`. Routes such as dialogs or popup menus
/// typically use this mechanism to return the value selected by the user to
/// the widget that created their route. The type of `result`, if provided,
/// must match the type argument of the class of the popped route (`T`).
///
/// The popped route and the route below it are notified (see [Route.didPop],
/// [Route.didComplete], and [Route.didPopNext]). If the [Navigator] has any
/// [Navigator.observers], they will be notified as well (see
/// [NavigatorObserver.didPop]).
///
/// The `T` type argument is the type of the return value of the popped route.
///
/// The type of `result`, if provided, must match the type argument of the
/// class of the popped route (`T`).
/// {@endtemplate}
///
/// {@tool snippet}
///
/// Typical usage for closing a route is as follows:
///
/// ```dart
/// void _close() {
/// Navigator.pop(context);
/// }
/// ```
/// {@end-tool}
///
/// A dialog box might be closed with a result:
///
/// ```dart
/// void _accept() {
/// Navigator.pop(context, true); // dialog returns true
/// }
/// ```
@optionalTypeArgs
static void pop<T extends Object>(BuildContext context, [ T result ]) {
Navigator.of(context).pop<T>(result);
}
/// Calls [pop] repeatedly on the navigator that most tightly encloses the
/// given context until the predicate returns true.
///
/// {@template flutter.widgets.navigator.popUntil}
/// The predicate may be applied to the same route more than once if
/// [Route.willHandlePopInternally] is true.
///
/// To pop until a route with a certain name, use the [RoutePredicate]
/// returned from [ModalRoute.withName].
///
/// The routes are closed with null as their `return` value.
///
/// See [pop] for more details of the semantics of popping a route.
/// {@endtemplate}
///
/// {@tool snippet}
///
/// Typical usage is as follows:
///
/// ```dart
/// void _logout() {
/// Navigator.popUntil(context, ModalRoute.withName('/login'));
/// }
/// ```
/// {@end-tool}
static void popUntil(BuildContext context, RoutePredicate predicate) {
Navigator.of(context).popUntil(predicate);
}
/// Immediately remove `route` from the navigator that most tightly encloses
/// the given context, and [Route.dispose] it.
///
/// {@template flutter.widgets.navigator.removeRoute}
/// The removed route is removed without being completed, so this method does
/// not take a return value argument. No animations are run as a result of
/// this method call.
///
/// The routes below and above the removed route are notified (see
/// [Route.didChangeNext] and [Route.didChangePrevious]). If the [Navigator]
/// has any [Navigator.observers], they will be notified as well (see
/// [NavigatorObserver.didRemove]). The removed route is disposed without
/// being notified. The future that had been returned from pushing that routes
/// will not complete.
///
/// The given `route` must be in the history; this method will throw an
/// exception if it is not.
///
/// Ongoing gestures within the current route are canceled.
/// {@endtemplate}
///
/// This method is used, for example, to instantly dismiss dropdown menus that
/// are up when the screen's orientation changes.
static void removeRoute(BuildContext context, Route<dynamic> route) {
return Navigator.of(context).removeRoute(route);
}
/// Immediately remove a route from the navigator that most tightly encloses
/// the given context, and [Route.dispose] it. The route to be removed is the
/// one below the given `anchorRoute`.
///
/// {@template flutter.widgets.navigator.removeRouteBelow}
/// The removed route is removed without being completed, so this method does
/// not take a return value argument. No animations are run as a result of
/// this method call.
///
/// The routes below and above the removed route are notified (see
/// [Route.didChangeNext] and [Route.didChangePrevious]). If the [Navigator]
/// has any [Navigator.observers], they will be notified as well (see
/// [NavigatorObserver.didRemove]). The removed route is disposed without
/// being notified. The future that had been returned from pushing that routes
/// will not complete.
///
/// The given `anchorRoute` must be in the history and must have a route below
/// it; this method will throw an exception if it is not or does not.
///
/// Ongoing gestures within the current route are canceled.
/// {@endtemplate}
static void removeRouteBelow(BuildContext context, Route<dynamic> anchorRoute) {
return Navigator.of(context).removeRouteBelow(anchorRoute);
}
/// The state from the closest instance of this class that encloses the given context.
///
/// Typical usage is as follows:
///
/// ```dart
/// Navigator.of(context)
/// ..pop()
/// ..pop()
/// ..pushNamed('/settings');
/// ```
///
/// If `rootNavigator` is set to true, the state from the furthest instance of
/// this class is given instead. Useful for pushing contents above all subsequent
/// instances of [Navigator].
static NavigatorState of(
BuildContext context, {
bool rootNavigator = false,
bool nullOk = false,
}) {
// Handles the case where the input context is a navigator element.
NavigatorState navigator;
if (context is StatefulElement && context.state is NavigatorState) {
navigator = context.state as NavigatorState;
}
if (rootNavigator) {
navigator = context.findRootAncestorStateOfType<NavigatorState>() ?? navigator;
} else {
navigator = navigator ?? context.findAncestorStateOfType<NavigatorState>();
}
assert(() {
if (navigator == null && !nullOk) {
throw FlutterError(
'Navigator operation requested with a context that does not include a Navigator.\n'
'The context used to push or pop routes from the Navigator must be that of a '
'widget that is a descendant of a Navigator widget.'
);
}
return true;
}());
return navigator;
}
/// Turn a route name into a set of [Route] objects.
///
/// This is the default value of [onGenerateInitialRoutes], which is used if
/// [initialRoute] is not null.
///
/// If this string starts with a `/` character and has multiple `/` characters
/// in it, then the string is split on those characters and substrings from
/// the start of the string up to each such character are, in turn, used as
/// routes to push.
///
/// For example, if the route `/stocks/HOOLI` was used as the [initialRoute],
/// then the [Navigator] would push the following routes on startup: `/`,
/// `/stocks`, `/stocks/HOOLI`. This enables deep linking while allowing the
/// application to maintain a predictable route history.
static List<Route<dynamic>> defaultGenerateInitialRoutes(NavigatorState navigator, String initialRouteName) {
final List<Route<dynamic>> result = <Route<dynamic>>[];
if (initialRouteName.startsWith('/') && initialRouteName.length > 1) {
initialRouteName = initialRouteName.substring(1); // strip leading '/'
assert(Navigator.defaultRouteName == '/');
List<String> debugRouteNames;
assert(() {
debugRouteNames = <String>[ Navigator.defaultRouteName ];
return true;
}());
result.add(navigator._routeNamed<dynamic>(Navigator.defaultRouteName, arguments: null, allowNull: true));
final List<String> routeParts = initialRouteName.split('/');
if (initialRouteName.isNotEmpty) {
String routeName = '';
for (final String part in routeParts) {
routeName += '/$part';
assert(() {
debugRouteNames.add(routeName);
return true;
}());
result.add(navigator._routeNamed<dynamic>(routeName, arguments: null, allowNull: true));
}
}
if (result.last == null) {
assert(() {
FlutterError.reportError(
FlutterErrorDetails(
exception:
'Could not navigate to initial route.\n'
'The requested route name was: "/$initialRouteName"\n'
'There was no corresponding route in the app, and therefore the initial route specified will be '
'ignored and "${Navigator.defaultRouteName}" will be used instead.'
),
);
return true;
}());
result.clear();
}
} else if (initialRouteName != Navigator.defaultRouteName) {
// If initialRouteName wasn't '/', then we try to get it with allowNull:true, so that if that fails,
// we fall back to '/' (without allowNull:true, see below).
result.add(navigator._routeNamed<dynamic>(initialRouteName, arguments: null, allowNull: true));
}
// Null route might be a result of gap in initialRouteName
//
// For example, routes = ['A', 'A/B/C'], and initialRouteName = 'A/B/C'
// This should result in result = ['A', null,'A/B/C'] where 'A/B' produces
// the null. In this case, we want to filter out the null and return
// result = ['A', 'A/B/C'].
result.removeWhere((Route<dynamic> route) => route == null);
if (result.isEmpty)
result.add(navigator._routeNamed<dynamic>(Navigator.defaultRouteName, arguments: null));
return result;
}
@override
NavigatorState createState() => NavigatorState();
}
// The _RouteLifecycle state machine (only goes down):
//
// [creation of a _RouteEntry]
// |
// +
// |\
// | \
// | staging
// | /
// |/
// +-+----------+--+-------+
// / | | |
// / | | |
// / | | |
// / | | |
// / | | |
// pushReplace push* add* replace*
// \ | | |
// \ | | /
// +--pushing# adding /
// \ / /
// \ / /
// idle--+-----+
// / \
// / \
// pop* remove*
// / \
// / removing#
// popping# |
// | |
// [finalizeRoute] |
// \ |
// dispose*
// |
// |
// disposed
// |
// |
// [_RouteEntry garbage collected]
// (terminal state)
//
// * These states are transient; as soon as _flushHistoryUpdates is run the
// route entry will exit that state.
// # These states await futures or other events, then transition automatically.
enum _RouteLifecycle {
staging, // we will wait for transition delegate to decide what to do with this route.
//
// routes that are present:
//
add, // we'll want to run install, didAdd, etc; a route created by onGenerateInitialRoutes or by the initial widget.pages
adding, // we'll waiting for the future from didPush of top-most route to complete
// routes that are ready for transition.
push, // we'll want to run install, didPush, etc; a route added via push() and friends
pushReplace, // we'll want to run install, didPush, etc; a route added via pushReplace() and friends
pushing, // we're waiting for the future from didPush to complete
replace, // we'll want to run install, didReplace, etc; a route added via replace() and friends
idle, // route is being harmless
//
// routes that are not present:
//
// routes that should be included in route announcement and should still listen to transition changes.
pop, // we'll want to call didPop
remove, // we'll want to run didReplace/didRemove etc
// routes should not be included in route announcement but should still listen to transition changes.
popping, // we're waiting for the route to call finalizeRoute to switch to dispose
removing, // we are waiting for subsequent routes to be done animating, then will switch to dispose
// routes that are completely removed from the navigator and overlay.
dispose, // we will dispose the route momentarily
disposed, // we have disposed the route
}
typedef _RouteEntryPredicate = bool Function(_RouteEntry entry);
class _NotAnnounced extends Route<void> {
// A placeholder for the lastAnnouncedPreviousRoute, the
// lastAnnouncedPoppedNextRoute, and the lastAnnouncedNextRoute before any
// change has been announced.
}
class _RouteEntry extends RouteTransitionRecord {
_RouteEntry(
this.route, {
@required _RouteLifecycle initialState,
}) : assert(route != null),
assert(initialState != null),
assert(
initialState == _RouteLifecycle.staging ||
initialState == _RouteLifecycle.add ||
initialState == _RouteLifecycle.push ||
initialState == _RouteLifecycle.pushReplace ||
initialState == _RouteLifecycle.replace
),
currentState = initialState;
@override
final Route<dynamic> route;
static Route<dynamic> notAnnounced = _NotAnnounced();
_RouteLifecycle currentState;
Route<dynamic> lastAnnouncedPreviousRoute = notAnnounced; // last argument to Route.didChangePrevious
Route<dynamic> lastAnnouncedPoppedNextRoute = notAnnounced; // last argument to Route.didPopNext
Route<dynamic> lastAnnouncedNextRoute = notAnnounced; // last argument to Route.didChangeNext
bool get hasPage => route.settings is Page;
bool canUpdateFrom(Page<dynamic> page) {
if (currentState.index > _RouteLifecycle.idle.index)
return false;
if (!hasPage)
return false;
final Page<dynamic> routePage = route.settings as Page<dynamic>;
return page.canUpdate(routePage);
}
void handleAdd({ @required NavigatorState navigator, @required Route<dynamic> previousPresent }) {
assert(currentState == _RouteLifecycle.add);
assert(navigator != null);
assert(navigator._debugLocked);
assert(route._navigator == null);
route._navigator = navigator;
route.install();
assert(route.overlayEntries.isNotEmpty);
currentState = _RouteLifecycle.adding;
navigator._observedRouteAdditions.add(
_NavigatorPushObservation(route, previousPresent)
);
}
void handlePush({ @required NavigatorState navigator, @required bool isNewFirst, @required Route<dynamic> previous, @required Route<dynamic> previousPresent }) {
assert(currentState == _RouteLifecycle.push || currentState == _RouteLifecycle.pushReplace || currentState == _RouteLifecycle.replace);
assert(navigator != null);
assert(navigator._debugLocked);
assert(
route._navigator == null,
'The pushed route has already been used. When pushing a route, a new '
'Route object must be provided.',
);
final _RouteLifecycle previousState = currentState;
route._navigator = navigator;
route.install();
assert(route.overlayEntries.isNotEmpty);
if (currentState == _RouteLifecycle.push || currentState == _RouteLifecycle.pushReplace) {
final TickerFuture routeFuture = route.didPush();
currentState = _RouteLifecycle.pushing;
routeFuture.whenCompleteOrCancel(() {
if (currentState == _RouteLifecycle.pushing) {
currentState = _RouteLifecycle.idle;
assert(!navigator._debugLocked);
assert(() { navigator._debugLocked = true; return true; }());
navigator._flushHistoryUpdates();
assert(() { navigator._debugLocked = false; return true; }());
}
});
} else {
assert(currentState == _RouteLifecycle.replace);
route.didReplace(previous);
currentState = _RouteLifecycle.idle;
}
if (isNewFirst) {
route.didChangeNext(null);
}
if (previousState == _RouteLifecycle.replace || previousState == _RouteLifecycle.pushReplace) {
navigator._observedRouteAdditions.add(
_NavigatorReplaceObservation(route, previousPresent)
);
} else {
assert(previousState == _RouteLifecycle.push);
navigator._observedRouteAdditions.add(
_NavigatorPushObservation(route, previousPresent)
);
}
}
void handleDidPopNext(Route<dynamic> poppedRoute) {
route.didPopNext(poppedRoute);
lastAnnouncedPoppedNextRoute = poppedRoute;
}
void handlePop({ @required NavigatorState navigator, @required Route<dynamic> previousPresent }) {
assert(navigator != null);
assert(navigator._debugLocked);
assert(route._navigator == navigator);
currentState = _RouteLifecycle.popping;
navigator._observedRouteDeletions.add(
_NavigatorPopObservation(route, previousPresent)
);
}
void handleRemoval({ @required NavigatorState navigator, @required Route<dynamic> previousPresent }) {
assert(navigator != null);
assert(navigator._debugLocked);
assert(route._navigator == navigator);
currentState = _RouteLifecycle.removing;
if (_reportRemovalToObserver) {
navigator._observedRouteDeletions.add(
_NavigatorRemoveObservation(route, previousPresent)
);
}
}
bool doingPop = false;
void didAdd({ @required NavigatorState navigator, @required bool isNewFirst}) {
route.didAdd();
currentState = _RouteLifecycle.idle;
if (isNewFirst) {
route.didChangeNext(null);
}
}
void pop<T>(T result) {
assert(isPresent);
doingPop = true;
if (route.didPop(result) && doingPop) {
currentState = _RouteLifecycle.pop;
}
doingPop = false;
}
bool _reportRemovalToObserver = true;
// Route is removed without being completed.
void remove({ bool isReplaced = false }) {
assert(
!hasPage || isWaitingForExitingDecision,
'A page-based route cannot be completed using imperative api, provide a '
'new list without the corresponding Page to Navigator.pages instead. '
);
if (currentState.index >= _RouteLifecycle.remove.index)
return;
assert(isPresent);
_reportRemovalToObserver = !isReplaced;
currentState = _RouteLifecycle.remove;
}
// Route completes with `result` and is removed.
void complete<T>(T result, { bool isReplaced = false }) {
assert(
!hasPage || isWaitingForExitingDecision,
'A page-based route cannot be completed using imperative api, provide a '
'new list without the corresponding Page to Navigator.pages instead. '
);
if (currentState.index >= _RouteLifecycle.remove.index)
return;
assert(isPresent);
_reportRemovalToObserver = !isReplaced;
route.didComplete(result);
assert(route._popCompleter.isCompleted); // implies didComplete was called
currentState = _RouteLifecycle.remove;
}
void finalize() {
assert(currentState.index < _RouteLifecycle.dispose.index);
currentState = _RouteLifecycle.dispose;
}
void dispose() {
assert(currentState.index < _RouteLifecycle.disposed.index);
route.dispose();
currentState = _RouteLifecycle.disposed;
}
bool get willBePresent {
return currentState.index <= _RouteLifecycle.idle.index &&
currentState.index >= _RouteLifecycle.add.index;
}
bool get isPresent {
return currentState.index <= _RouteLifecycle.remove.index &&
currentState.index >= _RouteLifecycle.add.index;
}
bool get suitableForAnnouncement {
return currentState.index <= _RouteLifecycle.removing.index &&
currentState.index >= _RouteLifecycle.push.index;
}
bool get suitableForTransitionAnimation {
return currentState.index <= _RouteLifecycle.remove.index &&
currentState.index >= _RouteLifecycle.push.index;
}
bool shouldAnnounceChangeToNext(Route<dynamic> nextRoute) {
assert(nextRoute != lastAnnouncedNextRoute);
// Do not announce if `next` changes from a just popped route to null. We
// already announced this change by calling didPopNext.
return !(
nextRoute == null &&
lastAnnouncedPoppedNextRoute != null &&
lastAnnouncedPoppedNextRoute == lastAnnouncedNextRoute
);
}
static final _RouteEntryPredicate isPresentPredicate = (_RouteEntry entry) => entry.isPresent;
static final _RouteEntryPredicate suitableForTransitionAnimationPredicate = (_RouteEntry entry) => entry.suitableForTransitionAnimation;
static final _RouteEntryPredicate willBePresentPredicate = (_RouteEntry entry) => entry.willBePresent;
static _RouteEntryPredicate isRoutePredicate(Route<dynamic> route) {
return (_RouteEntry entry) => entry.route == route;
}
@override
bool get isWaitingForEnteringDecision => currentState == _RouteLifecycle.staging;
@override
bool get isWaitingForExitingDecision => _isWaitingForExitingDecision;
bool _isWaitingForExitingDecision = false;
void markNeedsExitingDecision() => _isWaitingForExitingDecision = true;
@override
void markForPush() {
assert(
isWaitingForEnteringDecision && !isWaitingForExitingDecision,
'This route cannot be marked for push. Either a decision has already been '
'made or it does not require an explicit decision on how to transition in.'
);
currentState = _RouteLifecycle.push;
}
@override
void markForAdd() {
assert(
isWaitingForEnteringDecision && !isWaitingForExitingDecision,
'This route cannot be marked for add. Either a decision has already been '
'made or it does not require an explicit decision on how to transition in.'
);
currentState = _RouteLifecycle.add;
}
@override
void markForPop([dynamic result]) {
assert(
!isWaitingForEnteringDecision && isWaitingForExitingDecision && isPresent,
'This route cannot be marked for pop. Either a decision has already been '
'made or it does not require an explicit decision on how to transition out.'
);
pop<dynamic>(result);
_isWaitingForExitingDecision = false;
}
@override
void markForComplete([dynamic result]) {
assert(
!isWaitingForEnteringDecision && isWaitingForExitingDecision && isPresent,
'This route cannot be marked for complete. Either a decision has already '
'been made or it does not require an explicit decision on how to transition '
'out.'
);
complete<dynamic>(result);
_isWaitingForExitingDecision = false;
}
@override
void markForRemove() {
assert(
!isWaitingForEnteringDecision && isWaitingForExitingDecision && isPresent,
'This route cannot be marked for remove. Either a decision has already '
'been made or it does not require an explicit decision on how to transition '
'out.'
);
remove();
_isWaitingForExitingDecision = false;
}
}
abstract class _NavigatorObservation {
_NavigatorObservation(
this.primaryRoute,
this.secondaryRoute,
);
final Route<dynamic> primaryRoute;
final Route<dynamic> secondaryRoute;
void notify(NavigatorObserver observer);
}
class _NavigatorPushObservation extends _NavigatorObservation {
_NavigatorPushObservation(
Route<dynamic> primaryRoute,
Route<dynamic> secondaryRoute
) : super(primaryRoute, secondaryRoute);
@override
void notify(NavigatorObserver observer) {
observer.didPush(primaryRoute, secondaryRoute);
}
}
class _NavigatorPopObservation extends _NavigatorObservation {
_NavigatorPopObservation(
Route<dynamic> primaryRoute,
Route<dynamic> secondaryRoute
) : super(primaryRoute, secondaryRoute);
@override
void notify(NavigatorObserver observer) {
observer.didPop(primaryRoute, secondaryRoute);
}
}
class _NavigatorRemoveObservation extends _NavigatorObservation {
_NavigatorRemoveObservation(
Route<dynamic> primaryRoute,
Route<dynamic> secondaryRoute
) : super(primaryRoute, secondaryRoute);
@override
void notify(NavigatorObserver observer) {
observer.didRemove(primaryRoute, secondaryRoute);
}
}
class _NavigatorReplaceObservation extends _NavigatorObservation {
_NavigatorReplaceObservation(
Route<dynamic> primaryRoute,
Route<dynamic> secondaryRoute
) : super(primaryRoute, secondaryRoute);
@override
void notify(NavigatorObserver observer) {
observer.didReplace(newRoute: primaryRoute, oldRoute: secondaryRoute);
}
}
/// The state for a [Navigator] widget.
///
/// A reference to this class can be obtained by calling [Navigator.of].
class NavigatorState extends State<Navigator> with TickerProviderStateMixin {
final GlobalKey<OverlayState> _overlayKey = GlobalKey<OverlayState>();
List<_RouteEntry> _history = <_RouteEntry>[];
final Queue<_NavigatorObservation> _observedRouteAdditions = Queue<_NavigatorObservation>();
final Queue<_NavigatorObservation> _observedRouteDeletions = Queue<_NavigatorObservation>();
/// The [FocusScopeNode] for the [FocusScope] that encloses the routes.
final FocusScopeNode focusScopeNode = FocusScopeNode(debugLabel: 'Navigator Scope');
bool _debugLocked = false; // used to prevent re-entrant calls to push, pop, and friends
HeroController _heroControllerFromScope;
List<NavigatorObserver> _effectiveObservers;
@override
void initState() {
super.initState();
assert(
widget.pages.isEmpty || widget.onPopPage != null,
'The Navigator.onPopPage must be provided to use the Navigator.pages API',
);
for (final NavigatorObserver observer in widget.observers) {
assert(observer.navigator == null);
observer._navigator = this;
}
_effectiveObservers = widget.observers;
// We have to manually extract the inherited widget in initState because
// the current context is not fully initialized.
final HeroControllerScope heroControllerScope = context
.getElementForInheritedWidgetOfExactType<HeroControllerScope>()
?.widget as HeroControllerScope;
_updateHeroController(heroControllerScope?.controller);
String initialRoute = widget.initialRoute;
if (widget.pages.isNotEmpty) {
_history.addAll(
widget.pages.map((Page<dynamic> page) => _RouteEntry(
page.createRoute(context),
initialState: _RouteLifecycle.add,
))
);
} else {
// If there is no page provided, we will need to provide default route
// to initialize the navigator.
initialRoute = initialRoute ?? Navigator.defaultRouteName;
}
if (initialRoute != null) {
_history.addAll(
widget.onGenerateInitialRoutes(
this,
widget.initialRoute ?? Navigator.defaultRouteName
).map((Route<dynamic> route) =>
_RouteEntry(
route,
initialState: _RouteLifecycle.add,
),
),
);
}
assert(!_debugLocked);
assert(() { _debugLocked = true; return true; }());
_flushHistoryUpdates();
assert(() { _debugLocked = false; return true; }());
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
_updateHeroController(HeroControllerScope.of(context));
}
void _updateHeroController(HeroController newHeroController) {
if (_heroControllerFromScope != newHeroController) {
if (newHeroController != null) {
// Makes sure the same hero controller is not shared between two navigators.
assert(() {
// It is possible that the hero controller subscribes to an existing
// navigator. We are fine as long as that navigator gives up the hero
// controller at the end of the build.
if (newHeroController.navigator != null) {
final NavigatorState previousOwner = newHeroController.navigator;
ServicesBinding.instance.addPostFrameCallback((Duration timestamp) {
// We only check if this navigator still owns the hero controller.
if (_heroControllerFromScope == newHeroController) {
assert(_heroControllerFromScope._navigator == this);
assert(previousOwner._heroControllerFromScope != newHeroController);
}
});
}
return true;
}());
newHeroController._navigator = this;
}
// Only unsubscribe the hero controller when it is currently subscribe to
// this navigator.
if (_heroControllerFromScope?._navigator == this)
_heroControllerFromScope?._navigator = null;
_heroControllerFromScope = newHeroController;
_updateEffectiveObservers();
}
}
void _updateEffectiveObservers() {
if (_heroControllerFromScope != null)
_effectiveObservers = widget.observers + <NavigatorObserver>[_heroControllerFromScope];
else
_effectiveObservers = widget.observers;
}
@override
void didUpdateWidget(Navigator oldWidget) {
super.didUpdateWidget(oldWidget);
assert(
widget.pages.isEmpty || widget.onPopPage != null,
'The Navigator.onPopPage must be provided to use the Navigator.pages API',
);
if (oldWidget.observers != widget.observers) {
for (final NavigatorObserver observer in oldWidget.observers)
observer._navigator = null;
for (final NavigatorObserver observer in widget.observers) {
assert(observer.navigator == null);
observer._navigator = this;
}
_updateEffectiveObservers();
}
if (oldWidget.pages != widget.pages) {
assert(
widget.pages.isNotEmpty,
'To use the Navigator.pages, there must be at least one page in the list.'
);
_updatePages();
}
for (final _RouteEntry entry in _history)
entry.route.changedExternalState();
}
void _debugCheckDuplicatedPageKeys() {
assert((){
final Set<Key> keyReservation = <Key>{};
for (final Page<dynamic> page in widget.pages) {
if (page.key != null) {
assert(!keyReservation.contains(page.key));
keyReservation.add(page.key);
}
}
return true;
}());
}
@override
void dispose() {
assert(!_debugLocked);
assert(() {
_debugLocked = true;
return true;
}());
_updateHeroController(null);
for (final NavigatorObserver observer in _effectiveObservers)
observer._navigator = null;
focusScopeNode.dispose();
for (final _RouteEntry entry in _history)
entry.dispose();
super.dispose();
// don't unlock, so that the object becomes unusable
assert(_debugLocked);
}
/// The overlay this navigator uses for its visual presentation.
OverlayState get overlay => _overlayKey.currentState;
Iterable<OverlayEntry> get _allRouteOverlayEntries sync* {
for (final _RouteEntry entry in _history)
yield* entry.route.overlayEntries;
}
String _lastAnnouncedRouteName;
bool _debugUpdatingPage = false;
void _updatePages() {
assert(() {
assert(!_debugUpdatingPage);
_debugCheckDuplicatedPageKeys();
_debugUpdatingPage = true;
return true;
}());
// This attempts to diff the new pages list (widget.pages) with
// the old _RouteEntry[s] list (_history), and produces a new list of
// _RouteEntry[s] to be the new list of _history. This method roughly
// follows the same outline of RenderObjectElement.updateChildren.
//
// The cases it tries to optimize for are:
// - the old list is empty
// - All the pages in the new list can match the page-based routes in the old
// list, and their orders are the same.
// - there is an insertion or removal of one or more page-based route in
// only one place in the list
// If a page-based route with a key is in both lists, it will be synced.
// Page-based routes without keys might be synced but there is no guarantee.
// The general approach is to sync the entire new list backwards, as follows:
// 1. Walk the lists from the bottom, syncing nodes, and record pageless routes,
// until you no longer have matching nodes.
// 2. Walk the lists from the top, without syncing nodes, until you no
// longer have matching nodes. We'll sync these nodes at the end. We
// don't sync them now because we want to sync all the nodes in order
// from beginning to end.
// At this point we narrowed the old and new lists to the point
// where the nodes no longer match.
// 3. Walk the narrowed part of the old list to get the list of
// keys.
// 4. Walk the narrowed part of the new list forwards:
// * Create a new _RouteEntry for non-keyed items and record them for
// transitionDelegate.
// * Sync keyed items with the source if it exists.
// 5. Walk the narrowed part of the old list again to records the
// _RouteEntry[s], as well as pageless routes, needed to be removed for
// transitionDelegate.
// 5. Walk the top of the list again, syncing the nodes and recording
// pageless routes.
// 6. Use transitionDelegate for explicit decisions on how _RouteEntry[s]
// transition in or off the screens.
// 7. Fill pageless routes back into the new history.
bool needsExplicitDecision = false;
int newPagesBottom = 0;
int oldEntriesBottom = 0;
int newPagesTop = widget.pages.length - 1;
int oldEntriesTop = _history.length - 1;
final List<_RouteEntry> newHistory = <_RouteEntry>[];
final Map<_RouteEntry, List<_RouteEntry>> pageRouteToPagelessRoutes = <_RouteEntry, List<_RouteEntry>>{};
// Updates the bottom of the list.
_RouteEntry previousOldPageRouteEntry;
while (oldEntriesBottom <= oldEntriesTop) {
final _RouteEntry oldEntry = _history[oldEntriesBottom];
assert(oldEntry != null && oldEntry.currentState != _RouteLifecycle.disposed);
// Records pageless route. The bottom most pageless routes will be
// stored in key = null.
if (!oldEntry.hasPage) {
final List<_RouteEntry> pagelessRoutes = pageRouteToPagelessRoutes.putIfAbsent(
previousOldPageRouteEntry,
() => <_RouteEntry>[],
);
pagelessRoutes.add(oldEntry);
oldEntriesBottom += 1;
continue;
}
if (newPagesBottom > newPagesTop)
break;
final Page<dynamic> newPage = widget.pages[newPagesBottom];
if (!oldEntry.canUpdateFrom(newPage))
break;
previousOldPageRouteEntry = oldEntry;
oldEntry.route._updateSettings(newPage);
newHistory.add(oldEntry);
newPagesBottom += 1;
oldEntriesBottom += 1;
}
int pagelessRoutesToSkip = 0;
// Scans the top of the list until we found a page-based route that cannot be
// updated.
while ((oldEntriesBottom <= oldEntriesTop) && (newPagesBottom <= newPagesTop)) {
final _RouteEntry oldEntry = _history[oldEntriesTop];
assert(oldEntry != null && oldEntry.currentState != _RouteLifecycle.disposed);
if (!oldEntry.hasPage) {
// This route might need to be skipped if we can not find a page above.
pagelessRoutesToSkip += 1;
oldEntriesTop -= 1;
continue;
}
final Page<dynamic> newPage = widget.pages[newPagesTop];
if (!oldEntry.canUpdateFrom(newPage))
break;
// We found the page for all the consecutive pageless routes below. Those
// pageless routes do not need to be skipped.
pagelessRoutesToSkip = 0;
oldEntriesTop -= 1;
newPagesTop -= 1;
}
// Reverts the pageless routes that cannot be updated.
oldEntriesTop += pagelessRoutesToSkip;
// Scans middle of the old entries and records the page key to old entry map.
int oldEntriesBottomToScan = oldEntriesBottom;
final Map<LocalKey, _RouteEntry> pageKeyToOldEntry = <LocalKey, _RouteEntry>{};
while (oldEntriesBottomToScan <= oldEntriesTop) {
final _RouteEntry oldEntry = _history[oldEntriesBottomToScan];
oldEntriesBottomToScan += 1;
assert(
oldEntry != null &&
oldEntry.currentState != _RouteLifecycle.disposed
);
// Pageless routes will be recorded when we update the middle of the old
// list.
if (!oldEntry.hasPage)
continue;
assert(oldEntry.hasPage);
final Page<dynamic> page = oldEntry.route.settings as Page<dynamic>;
if (page.key == null)
continue;
assert(!pageKeyToOldEntry.containsKey(page.key));
pageKeyToOldEntry[page.key] = oldEntry;
}
// Updates the middle of the list.
while (newPagesBottom <= newPagesTop) {
final Page<dynamic> nextPage = widget.pages[newPagesBottom];
newPagesBottom += 1;
if (
nextPage.key == null ||
!pageKeyToOldEntry.containsKey(nextPage.key) ||
!pageKeyToOldEntry[nextPage.key].canUpdateFrom(nextPage)
) {
// There is no matching key in the old history, we need to create a new
// route and wait for the transition delegate to decide how to add
// it into the history.
final _RouteEntry newEntry = _RouteEntry(
nextPage.createRoute(context),
initialState: _RouteLifecycle.staging,
);
needsExplicitDecision = true;
assert(
newEntry.route.settings == nextPage,
'The settings getter of a page-based Route must return a Page object. '
'Please set the settings to the Page in the Page.createRoute method.'
);
newHistory.add(newEntry);
} else {
// Removes the key from pageKeyToOldEntry to indicate it is taken.
final _RouteEntry matchingEntry = pageKeyToOldEntry.remove(nextPage.key);
assert(matchingEntry.canUpdateFrom(nextPage));
matchingEntry.route._updateSettings(nextPage);
newHistory.add(matchingEntry);
}
}
// Any remaining old routes that do not have a match will need to be removed.
final Map<RouteTransitionRecord, RouteTransitionRecord> locationToExitingPageRoute = <RouteTransitionRecord, RouteTransitionRecord>{};
while (oldEntriesBottom <= oldEntriesTop) {
final _RouteEntry potentialEntryToRemove = _history[oldEntriesBottom];
oldEntriesBottom += 1;
if (!potentialEntryToRemove.hasPage) {
assert(previousOldPageRouteEntry != null);
final List<_RouteEntry> pagelessRoutes = pageRouteToPagelessRoutes
.putIfAbsent(
previousOldPageRouteEntry,
() => <_RouteEntry>[],
);
pagelessRoutes.add(potentialEntryToRemove);
if (previousOldPageRouteEntry.isWaitingForExitingDecision)
potentialEntryToRemove.markNeedsExitingDecision();
continue;
}
final Page<dynamic> potentialPageToRemove = potentialEntryToRemove.route.settings as Page<dynamic>;
// Marks for transition delegate to remove if this old page does not have
// a key or was not taken during updating the middle of new page.
if (
potentialPageToRemove.key == null ||
pageKeyToOldEntry.containsKey(potentialPageToRemove.key)
) {
locationToExitingPageRoute[previousOldPageRouteEntry] = potentialEntryToRemove;
// We only need a decision if it has not already been popped.
if (potentialEntryToRemove.isPresent)
potentialEntryToRemove.markNeedsExitingDecision();
}
previousOldPageRouteEntry = potentialEntryToRemove;
}
// We've scanned the whole list.
assert(oldEntriesBottom == oldEntriesTop + 1);
assert(newPagesBottom == newPagesTop + 1);
newPagesTop = widget.pages.length - 1;
oldEntriesTop = _history.length - 1;
// Verifies we either reach the bottom or the oldEntriesBottom must be updatable
// by newPagesBottom.
assert(() {
if (oldEntriesBottom <= oldEntriesTop)
return newPagesBottom <= newPagesTop &&
_history[oldEntriesBottom].hasPage &&
_history[oldEntriesBottom].canUpdateFrom(widget.pages[newPagesBottom]);
else
return newPagesBottom > newPagesTop;
}());
// Updates the top of the list.
while ((oldEntriesBottom <= oldEntriesTop) && (newPagesBottom <= newPagesTop)) {
final _RouteEntry oldEntry = _history[oldEntriesBottom];
assert(oldEntry != null && oldEntry.currentState != _RouteLifecycle.disposed);
if (!oldEntry.hasPage) {
assert(previousOldPageRouteEntry != null);
final List<_RouteEntry> pagelessRoutes = pageRouteToPagelessRoutes
.putIfAbsent(
previousOldPageRouteEntry,
() => <_RouteEntry>[]
);
pagelessRoutes.add(oldEntry);
continue;
}
previousOldPageRouteEntry = oldEntry;
final Page<dynamic> newPage = widget.pages[newPagesBottom];
assert(oldEntry.canUpdateFrom(newPage));
oldEntry.route._updateSettings(newPage);
newHistory.add(oldEntry);
oldEntriesBottom += 1;
newPagesBottom += 1;
}
// Finally, uses transition delegate to make explicit decision if needed.
needsExplicitDecision = needsExplicitDecision || locationToExitingPageRoute.isNotEmpty;
Iterable<_RouteEntry> results = newHistory;
if (needsExplicitDecision) {
results = widget.transitionDelegate._transition(
newPageRouteHistory: newHistory,
locationToExitingPageRoute: locationToExitingPageRoute,
pageRouteToPagelessRoutes: pageRouteToPagelessRoutes,
).cast<_RouteEntry>();
}
_history = <_RouteEntry>[];
// Adds the leading pageless routes if there is any.
if (pageRouteToPagelessRoutes.containsKey(null)) {
_history.addAll(pageRouteToPagelessRoutes[null]);
}
for (final _RouteEntry result in results) {
_history.add(result);
if (pageRouteToPagelessRoutes.containsKey(result)) {
_history.addAll(pageRouteToPagelessRoutes[result]);
}
}
assert(() {_debugUpdatingPage = false; return true;}());
assert(() { _debugLocked = true; return true; }());
_flushHistoryUpdates();
assert(() { _debugLocked = false; return true; }());
}
void _flushHistoryUpdates({bool rearrangeOverlay = true}) {
assert(_debugLocked && !_debugUpdatingPage);
// Clean up the list, sending updates to the routes that changed. Notably,
// we don't send the didChangePrevious/didChangeNext updates to those that
// did not change at this point, because we're not yet sure exactly what the
// routes will be at the end of the day (some might get disposed).
int index = _history.length - 1;
_RouteEntry next;
_RouteEntry entry = _history[index];
_RouteEntry previous = index > 0 ? _history[index - 1] : null;
bool canRemoveOrAdd = false; // Whether there is a fully opaque route on top to silently remove or add route underneath.
Route<dynamic> poppedRoute; // The route that should trigger didPopNext on the top active route.
bool seenTopActiveRoute = false; // Whether we've seen the route that would get didPopNext.
final List<_RouteEntry> toBeDisposed = <_RouteEntry>[];
while (index >= 0) {
switch (entry.currentState) {
case _RouteLifecycle.add:
assert(rearrangeOverlay);
entry.handleAdd(
navigator: this,
previousPresent: _getRouteBefore(index - 1, _RouteEntry.isPresentPredicate)?.route,
);
assert(entry.currentState == _RouteLifecycle.adding);
continue;
case _RouteLifecycle.adding:
if (canRemoveOrAdd || next == null) {
entry.didAdd(
navigator: this,
isNewFirst: next == null
);
assert(entry.currentState == _RouteLifecycle.idle);
continue;
}
break;
case _RouteLifecycle.push:
case _RouteLifecycle.pushReplace:
case _RouteLifecycle.replace:
assert(rearrangeOverlay);
entry.handlePush(
navigator: this,
previous: previous?.route,
previousPresent: _getRouteBefore(index - 1, _RouteEntry.isPresentPredicate)?.route,
isNewFirst: next == null,
);
assert(entry.currentState != _RouteLifecycle.push);
assert(entry.currentState != _RouteLifecycle.pushReplace);
assert(entry.currentState != _RouteLifecycle.replace);
if (entry.currentState == _RouteLifecycle.idle) {
continue;
}
break;
case _RouteLifecycle.pushing: // Will exit this state when animation completes.
if (!seenTopActiveRoute && poppedRoute != null)
entry.handleDidPopNext(poppedRoute);
seenTopActiveRoute = true;
break;
case _RouteLifecycle.idle:
if (!seenTopActiveRoute && poppedRoute != null)
entry.handleDidPopNext(poppedRoute);
seenTopActiveRoute = true;
// This route is idle, so we are allowed to remove subsequent (earlier)
// routes that are waiting to be removed silently:
canRemoveOrAdd = true;
break;
case _RouteLifecycle.pop:
if (!seenTopActiveRoute) {
if (poppedRoute != null)
entry.handleDidPopNext(poppedRoute);
poppedRoute = entry.route;
}
entry.handlePop(
navigator: this,
previousPresent: _getRouteBefore(index, _RouteEntry.willBePresentPredicate)?.route,
);
assert(entry.currentState == _RouteLifecycle.popping);
canRemoveOrAdd = true;
break;
case _RouteLifecycle.popping:
// Will exit this state when animation completes.
break;
case _RouteLifecycle.remove:
if (!seenTopActiveRoute) {
if (poppedRoute != null)
entry.route.didPopNext(poppedRoute);
poppedRoute = null;
}
entry.handleRemoval(
navigator: this,
previousPresent: _getRouteBefore(index, _RouteEntry.willBePresentPredicate)?.route,
);
assert(entry.currentState == _RouteLifecycle.removing);
continue;
case _RouteLifecycle.removing:
if (!canRemoveOrAdd && next != null) {
// We aren't allowed to remove this route yet.
break;
}
entry.currentState = _RouteLifecycle.dispose;
continue;
case _RouteLifecycle.dispose:
// Delay disposal until didChangeNext/didChangePrevious have been sent.
toBeDisposed.add(_history.removeAt(index));
entry = next;
break;
case _RouteLifecycle.disposed:
case _RouteLifecycle.staging:
assert(false);
break;
}
index -= 1;
next = entry;
entry = previous;
previous = index > 0 ? _history[index - 1] : null;
}
// Informs navigator observers about route changes.
_flushObserverNotifications();
// Now that the list is clean, send the didChangeNext/didChangePrevious
// notifications.
_flushRouteAnnouncement();
// Announces route name changes.
if (widget.reportsRouteUpdateToEngine) {
final _RouteEntry lastEntry = _history.lastWhere(
_RouteEntry.isPresentPredicate, orElse: () => null);
final String routeName = lastEntry?.route?.settings?.name;
if (routeName != _lastAnnouncedRouteName) {
SystemNavigator.routeUpdated(
routeName: routeName,
previousRouteName: _lastAnnouncedRouteName
);
_lastAnnouncedRouteName = routeName;
}
}
// Lastly, removes the overlay entries of all marked entries and disposes
// them.
for (final _RouteEntry entry in toBeDisposed) {
for (final OverlayEntry overlayEntry in entry.route.overlayEntries)
overlayEntry.remove();
entry.dispose();
}
if (rearrangeOverlay)
overlay?.rearrange(_allRouteOverlayEntries);
}
void _flushObserverNotifications() {
if (_effectiveObservers.isEmpty) {
_observedRouteDeletions.clear();
_observedRouteAdditions.clear();
return;
}
while (_observedRouteAdditions.isNotEmpty) {
final _NavigatorObservation observation = _observedRouteAdditions.removeLast();
_effectiveObservers.forEach(observation.notify);
}
while (_observedRouteDeletions.isNotEmpty) {
final _NavigatorObservation observation = _observedRouteDeletions.removeFirst();
_effectiveObservers.forEach(observation.notify);
}
}
void _flushRouteAnnouncement() {
int index = _history.length - 1;
while (index >= 0) {
final _RouteEntry entry = _history[index];
if (!entry.suitableForAnnouncement) {
index -= 1;
continue;
}
final _RouteEntry next = _getRouteAfter(index + 1, _RouteEntry.suitableForTransitionAnimationPredicate);
if (next?.route != entry.lastAnnouncedNextRoute) {
if (entry.shouldAnnounceChangeToNext(next?.route)) {
entry.route.didChangeNext(next?.route);
}
entry.lastAnnouncedNextRoute = next?.route;
}
final _RouteEntry previous = _getRouteBefore(index - 1, _RouteEntry.suitableForTransitionAnimationPredicate);
if (previous?.route != entry.lastAnnouncedPreviousRoute) {
entry.route.didChangePrevious(previous?.route);
entry.lastAnnouncedPreviousRoute = previous?.route;
}
index -= 1;
}