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!FlutterPods.md
Raw
main.dart
import 'dart:async';
import 'dart:math';
import 'package:flutter/material.dart';
void main() {
runApp(
const PodsScope(
child: MainApp(),
),
);
}
/* Start Example */
final StatePod<int> counterPod = StatePod((_) => 0);
final FuturePod<int> randomIntPod = FuturePod(
(Ref ref) {
int value = Random().nextInt(1000);
ref.onDispose(() {
debugPrint(('randomInt-disposed', value).toString());
});
return Future<int>.delayed(
const Duration(seconds: 2),
() => value,
);
},
);
final ValueMapper<int, FuturePod<int>> dependOnRandomIntPod = FuturePod.family(
(Ref ref, int multiplier) async {
final int value = await ref.watch(randomIntPod.future);
return value * multiplier;
},
);
final StreamPod<int> timerPod = StreamPod(
(Ref ref) async* {
// This should cause timer to restart everytime count changes
final int count = max(1, ref.watch(counterPod));
for (int i = count; i >= 0; i--) {
await Future<void>.delayed(const Duration(seconds: 1));
yield i;
}
},
);
final FuturePod<bool> moduloPod = FuturePod(
(Ref ref) => ref.watch(
timerPod.selectAsync((int value) => value % 5 == 0),
),
);
class MainApp extends StatelessWidget {
const MainApp({super.key});
@override
Widget build(BuildContext context) {
context.listen(counterPod, (int? previous, int next) {
debugPrint(('counter-changed', previous, next).toString());
});
context.listen(timerPod, (AsyncValue<int>? previous, AsyncValue<int> next) {
debugPrint(('timer-changed', previous, next).toString());
});
context.listen(moduloPod, (AsyncValue<bool>? previous, AsyncValue<bool> next) {
debugPrint(('modulo-changed', previous, next).toString());
});
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: const Text('Pods')),
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
// Wrapped in a Builder so 'watch' doesn't propagate upwards
Builder(
builder: (BuildContext context) => Column(
children: <Widget>[
switch (context.watch(randomIntPod)) {
PendingAsyncValue() => const Text('Loading...'),
SuccessfulAsyncValue(:final int data) => Text('Random => $data'),
FailedAsyncValue() => const Text('Failed!'),
},
const SizedBox(height: 16),
switch (context.watch(dependOnRandomIntPod(10))) {
PendingAsyncValue() => const Text('Loading...'),
SuccessfulAsyncValue(:final int data) => Text('Depends on Random => $data'),
FailedAsyncValue() => const Text('Failed!'),
},
const SizedBox(height: 16),
TextButton(
onPressed: () => context.invalidate(randomIntPod),
child: const Text('Invalidate Random'),
),
],
),
),
const SizedBox(height: 24),
const Divider(),
const SizedBox(height: 24),
// Wrapped in a Builder so 'watch' doesn't propagate upwards
Builder(
builder: (BuildContext context) => Column(
children: <Widget>[
switch (context.watch(timerPod)) {
PendingAsyncValue() => const Text('Loading...'),
SuccessfulAsyncValue(:final int data) => Text('Countdown => $data'),
FailedAsyncValue() => const Text('Failed!'),
},
const SizedBox(height: 16),
switch (context.watch(moduloPod)) {
PendingAsyncValue() => const Text('Loading...'),
SuccessfulAsyncValue(:final bool data) => Text('Modulo => $data'),
FailedAsyncValue() => const Text('Failed!'),
},
],
),
),
const SizedBox(height: 24),
const _Counter(),
const SizedBox(height: 24),
const PodsScope(
overrides: <PodOverride>[
// An override for `counterPod` can also be introduced here
// counterPod.overrideWith((_) => 10),
],
child: PodsScope(
overrides: <PodOverride>[
// An override for `counterPod` can also be introduced here
// counterPod.overrideWith((_) => 100),
],
child: PodsScope(
overrides: <PodOverride>[
// An override for `counterPod` can also be introduced here
// counterPod.overrideWith((_) => 1000),
],
child: _Counter(),
),
),
),
],
),
),
),
);
}
}
class _Counter extends StatelessWidget {
const _Counter();
@override
Widget build(BuildContext context) {
return Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Row(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
TextButton(
onPressed: () => context.read(counterPod.notifier).state--,
child: const Text('-'),
),
Padding(
padding: const EdgeInsets.symmetric(horizontal: 16.0),
child: Row(
children: <Widget>[
// Wrapped in a Builder so 'watch' doesn't propagate upwards
Builder(
builder: (BuildContext context) => Text(
'${context.watch(counterPod)}',
),
),
const Text(' % 5 == 0 ? '),
// Wrapped in a Builder so 'watch' doesn't propagate upwards. Also it uses a selector
Builder(
builder: (BuildContext context) => Text(
'${context.watch(counterPod.select((int counter) => counter % 5 == 0))}',
),
),
],
),
),
TextButton(
onPressed: () => context.read(counterPod.notifier).state++,
child: const Text('+'),
),
],
),
const SizedBox(height: 4),
TextButton(
// This should reset its state to default, rebuild all dependent pods + widgets & notify all listeners
onPressed: () => context.invalidate(counterPod),
child: const Text('Invalidate Counter'),
),
],
);
}
}
/* End Example */
/* Start PodsScope */
class PodsScope extends StatefulWidget {
const PodsScope({
super.key,
this.overrides = const <PodOverride>[],
required this.child,
});
final List<PodOverride> overrides;
final Widget child;
static _PodsScope _of(BuildContext context, {bool listen = false}) {
final _PodsScope? scope = listen
? context.getInheritedWidgetOfExactType<_PodsScope>()
: context.dependOnInheritedWidgetOfExactType<_PodsScope>();
if (scope == null) {
throw Exception('Missing PodsScope');
}
return scope;
}
@override
State<PodsScope> createState() => _PodsScopeState();
}
typedef _PodScopeSubscriptionKey = (Pod, BuildContext);
typedef _PodScopeSubscriptions = Map<_PodScopeSubscriptionKey, PodSubscription>;
class _PodsScopeState extends State<PodsScope> {
final _PodScopeSubscriptions _dependents = <_PodScopeSubscriptionKey, PodSubscription>{};
final _PodScopeSubscriptions _listeners = <_PodScopeSubscriptionKey, PodSubscription>{};
late final Pods _pods = Pods(parent: _parent, overrides: widget.overrides);
Pods? get _parent => context.getInheritedWidgetOfExactType<_PodsScope>()?.state._pods;
@override
void didUpdateWidget(covariant PodsScope oldWidget) {
assert(widget.overrides.length == oldWidget.overrides.length, "You shouldn't add or remove overrides");
_pods.updateOverrides(widget.overrides, _parent);
super.didUpdateWidget(oldWidget);
}
@override
void dispose() {
_dependents
..forEach((_, PodSubscription sub) => sub.close())
..clear();
_listeners
..forEach((_, PodSubscription sub) => sub.close())
..clear();
_pods.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) => _PodsScope(state: this, child: widget.child);
}
class _PodsScope extends InheritedWidget {
const _PodsScope({required this.state, required super.child});
final _PodsScopeState state;
@override
bool updateShouldNotify(covariant _PodsScope oldWidget) => false;
}
/* End PodsScope */
/* Start PodsProvider extension */
extension PodsProvider on BuildContext {
_PodsScopeState get _state => PodsScope._of(this).state;
U read<U>(Pod<U> pod) => _state._pods.read(pod);
U watch<U>(NotifiablePod<U> pod) {
final _PodScopeSubscriptionKey key = (pod, this);
final _PodsScopeState state = PodsScope._of(this, listen: true).state;
if (state._dependents[key] case final PodSubscription subscription) {
return subscription.read() as U;
}
return state._dependents
.putIfAbsent(
key,
() => state._pods.listen<U>(pod, (_, __) {
if (this case final Element element when element.debugIsActive) {
element.markNeedsBuild();
} else {
scheduleMicrotask(() => state._dependents
..[key]!.close()
..remove(key));
}
}),
)
.read() as U;
}
PodSubscription<U> listen<U>(
ListenablePod<U> pod,
PodListener<U> listener, {
bool fireImmediately = false,
}) {
final _PodScopeSubscriptionKey key = (pod, this);
final _PodScopeSubscriptions listeners = _PodScopeSubscriptions.of(_state._listeners);
try {
listeners.forEach((_PodScopeSubscriptionKey subKey, PodSubscription subscription) {
if (subKey == key) {
subscription.close();
_state._listeners.remove(key);
}
});
return _state._listeners.putIfAbsent(
key,
() => _state._pods.listen<U>(pod, listener),
) as PodSubscription<U>;
} finally {
listeners.clear();
}
}
void invalidate<U>(Pod<U> pod) => _state._pods.invalidate(pod);
}
/* End PodsProvider extension */
/* Start Pods */
typedef VoidCallback = void Function();
typedef ValueCallback<T> = T Function();
typedef ValueMapper<U, T> = T Function(U);
@optionalTypeArgs
typedef PodOverride<T> = ({Pod<T> origin, Pod<T> override});
@optionalTypeArgs
typedef PodSubscription<U> = ({ValueCallback<U> read, VoidCallback close});
typedef PodListener<U> = void Function(U? previous, U next);
typedef PodFactory<T> = ValueMapper<Ref, T>;
typedef PodUpdater<T> = ValueMapper<T?, T>;
typedef FamilyPodFactory<T, U> = T Function(Ref ref, U args);
abstract interface class Ref {
U read<U>(Pod<U> pod);
U watch<U>(WatchablePod<U> pod);
PodSubscription<U> listen<U>(
ListenablePod<U> pod,
PodListener<U> listener, {
bool fireImmediately = false,
});
void invalidate<U>(Pod<U> pod);
void onDispose(VoidCallback callback);
}
/* End Pods */
/* Start Pod Element */
@optionalTypeArgs
abstract base class PodElement<T> {
PodElement([this._state]);
String? _debugLabel;
late Ref _ref;
final Set<PodListener<T>> _listeners = <PodListener<T>>{};
final Set<PodElement> _references = <PodElement>{};
final Set<PodElement> _dependents = <PodElement>{};
final Set<VoidCallback> _disposeListener = <VoidCallback>{};
@protected
T get state => _state!;
T? _state;
@protected
set state(T newState) {
final T? oldState = _state;
_state = newState;
_notifyListeners(oldState);
}
@protected
bool get mounted => _state != null;
@override
bool operator ==(Object other) =>
identical(this, other) || other is PodElement<T> && runtimeType == other.runtimeType;
@override
int get hashCode => identityHashCode(this);
@mustCallSuper
void mount(covariant Ref ref) {
assert(state != null, 'Set the state after mount');
_ref = ref;
}
@mustCallSuper
void dispose() {
_notifyDisposeCallbacks();
_state = null;
_debugLabel = null;
_listeners.clear();
_dependents.clear();
_references.clear();
}
@override
String toString() => (StringBuffer()
..write(_debugLabel != null ? '${_debugLabel}Element' : '$runtimeType')
..write('($hashCode)'))
.toString();
// todo: maybe do not mount immediately
// todo: maybe introduce a scheduler
void _invalidate() {
_notifyDisposeCallbacks();
Future<void>(() {
if (_ref case final Ref ref) {
final T? oldState = _state;
mount(ref);
_notifyListeners(oldState);
}
});
}
void _attachTo(PodElement element) => element._references.add(this);
void _dependsOn(PodElement element) => element._dependents.add(this);
VoidCallback _addListener(PodListener<T> listener) {
_listeners.add(listener);
return () => _listeners.remove(listener);
}
void _addDisposeListener(VoidCallback callback) => _disposeListener.add(callback);
@protected
void _notifyListeners(T? oldState) {
if (oldState == state) {
return;
}
for (int i = 0; i < _listeners.length; i++) {
_listeners.elementAt(i)(oldState, state);
}
for (int i = _dependents.length - 1; i >= 0; i--) {
final PodElement dependent = _dependents.elementAt(i);
dependent.mount(dependent._ref);
}
}
void _notifyDisposeCallbacks() {
for (final VoidCallback callback in _disposeListener) {
callback();
}
_disposeListener.clear();
}
}
/* End Pod Element */
/* Start Pod */
@optionalTypeArgs
abstract base class Pod<T> {
const Pod({this.debugLabel});
final String? debugLabel;
static ValueMapper<U, V> _family<U, V>(ValueMapper<U, V> factory) => (U args) => factory(args);
@factory
PodElement<T> createElement();
@override
bool operator ==(Object other) =>
identical(this, other) || other is Pod<T> && runtimeType == other.runtimeType && debugLabel == other.debugLabel;
@override
int get hashCode => debugLabel?.hashCode ?? identityHashCode(this);
@override
String toString() => '${debugLabel ?? runtimeType}($hashCode)';
}
@optionalTypeArgs
base mixin ListenablePod<T> on Pod<T> {}
@optionalTypeArgs
base mixin WatchablePod<T> on Pod<T> {}
@optionalTypeArgs
base mixin NotifiablePod<T> implements WatchablePod<T>, ListenablePod<T> {}
@optionalTypeArgs
base mixin AsyncPod<T, U> implements NotifiablePod<AsyncValue<T>> {
PodFactory<U> get _factory;
WatchablePod<FutureOr<T>> get future;
}
/* End Pod */
/* Start Pods Container */
class Pods implements Ref {
Pods({
Pods? parent,
PodElement? owner,
List<PodOverride> overrides = const <PodOverride>[],
}) : this._(
owner: owner ?? (_AnonymousPodElement().._debugLabel = 'RootElement'),
pods: <Pod, PodElement>{
...?parent?._pods,
},
overrides: <Pod, Pod>{
...?parent?._overrides,
for (final PodOverride entry in overrides) entry.origin: entry.override,
},
);
const Pods._({
required PodElement owner,
required Map<Pod, PodElement> pods,
required Map<Pod, Pod> overrides,
}) : _owner = owner,
_pods = pods,
_overrides = overrides;
final PodElement _owner;
final Map<Pod, PodElement> _pods;
final Map<Pod, Pod> _overrides;
@override
U read<U>(Pod<U> pod) => _resolvePodElement(pod).state;
@Deprecated('.watch is not supported in CLI mode, instead use .listen')
@override
U watch<U>(WatchablePod<U> pod) {
final PodElement<U> element = _resolvePodElement(pod);
_owner._dependsOn(element);
return element.state;
}
@override
PodSubscription<U> listen<U>(
ListenablePod<U> pod,
PodListener<U> listener, {
bool fireImmediately = false,
}) {
final PodElement<U> element = _resolvePodElement(pod, shouldMount: false);
final VoidCallback dispose = element._addListener(listener);
if (!element.mounted) {
_mountPodElement(element);
}
if (fireImmediately) {
listener(null, element.state);
}
return (
read: () => element.state,
close: dispose,
);
}
@override
void invalidate<U>(Pod<U> pod) {
return switch ((_pods[pod], _overrides[pod])) {
(_, Pod<U> podOverride) => invalidate(podOverride),
(PodElement<U> element, _) => element._invalidate(),
_ => null,
};
}
@Deprecated('not supposed to use this directly')
@override
void onDispose(VoidCallback callback) => _owner._addDisposeListener(callback);
void updateOverrides(List<PodOverride> overrides, Pods? parent) {
Map<Pod, Pod>? parentOverrides = parent?._overrides;
final Set<PodOverride> combinedOverrides = <PodOverride>{
if (parentOverrides != null)
for (final MapEntry<Pod, Pod> entry in parentOverrides.entries) (origin: entry.key, override: entry.value),
...overrides,
};
for (final PodOverride entry in combinedOverrides) {
final Pod? previousOverride = _overrides[entry.origin];
_pods
..[previousOverride]?.dispose()
..remove(previousOverride);
_overrides[entry.origin] = entry.override;
}
}
void dispose() {
Future<void>(() {
_pods
..forEach((_, PodElement pod) => pod.dispose())
..clear();
_overrides.clear();
_owner.dispose();
});
}
@override
bool operator ==(Object other) =>
identical(this, other) ||
other is Pods &&
runtimeType == other.runtimeType &&
_owner == other._owner &&
_pods == other._pods &&
_overrides == other._overrides;
@override
int get hashCode => _owner.hashCode ^ _pods.hashCode ^ _overrides.hashCode;
@override
String toString() => 'Ref($hashCode)';
@visibleForTesting
PodElement<U> element<U>(Pod<U> pod) => _resolvePodElement(pod);
@visibleForTesting
Future<void> pump() => Future<void>.microtask(() {});
PodElement<U> _resolvePodElement<U>(Pod<U> pod, {bool shouldMount = true}) {
switch ((_pods[pod], _overrides[pod])) {
case (_, Pod<U> podOverride):
return _resolvePodElement(podOverride, shouldMount: shouldMount);
case (PodElement<U> element, _):
return element.._attachTo(_owner);
case _:
final PodElement<U> element = pod.createElement()
.._debugLabel = pod.debugLabel
.._attachTo(_owner);
_pods[pod] = element;
if (shouldMount) {
_mountPodElement(element);
}
return element;
}
}
void _mountPodElement(PodElement element) => element.mount(
Pods._(
owner: element,
pods: _pods,
overrides: _overrides,
),
);
}
/* End Pods Container */
/* Start Pod Types */
extension PodOverrideWith<T> on Pod<T> {
PodOverride<T> overrideWith(PodFactory<T> factory) => (
origin: this,
override: _ProxyPod(factory, debugLabel: 'Override<$this>'),
);
}
extension PodSelector<T> on NotifiablePod<T> {
NotifiablePod<U> select<U>(ValueMapper<T, U> selector) => _SelectorPod(
(Ref ref) => selector(ref.watch(this)),
debugLabel: 'Selector<$this>',
);
}
extension AsyncPodSelector<T, V> on AsyncPod<T, V> {
NotifiablePod<Future<U>> selectAsync<U>(ValueMapper<T, U> selector) => _AsyncSelectorPod<T, U, V>(
_factory,
selector,
debugLabel: 'AsyncSelector<$this>',
);
}
@optionalTypeArgs
final class ValuePod<T> extends Pod<T> {
const ValuePod(this._factory, {super.debugLabel});
static ValueMapper<U, ValuePod<T>> family<T, U>(
FamilyPodFactory<T, U> factory, {
String? debugLabel,
}) {
return Pod._family(
(U args) => ValuePod<T>(
(Ref ref) => factory(ref, args),
debugLabel: '${debugLabel ?? 'ValueFamily'}<$args>',
),
);
}
final PodFactory<T> _factory;
@override
PodElement<T> createElement() => _ValuePodElement<T>(this);
}
@optionalTypeArgs
final class StatePod<T> extends ValuePod<T> with NotifiablePod<T> {
StatePod(super._factory, {super.debugLabel});
static ValueMapper<U, StatePod<T>> family<T, U>(
FamilyPodFactory<T, U> factory, {
String? debugLabel,
}) {
return Pod._family(
(U args) => StatePod<T>(
(Ref ref) => factory(ref, args),
debugLabel: '${debugLabel ?? 'StateFamily'}<$args>',
),
);
}
late final Pod<Notifier<T>> notifier = _ProxyPod(
(Ref ref) {
Pods pods = (ref as Pods);
return Notifier(
() => pods._resolvePodElement(this).state,
(T state) => pods._resolvePodElement(this, shouldMount: false).state = state,
);
},
debugLabel: 'Notifier<$this>',
);
}
@optionalTypeArgs
final class FuturePod<T> extends _AsyncValuePod<T, FutureOr<T>> {
FuturePod(super._factory, {super.debugLabel});
static ValueMapper<U, FuturePod<T>> family<T, U>(
FamilyPodFactory<FutureOr<T>, U> factory, {
String? debugLabel,
}) {
return Pod._family(
(U args) => FuturePod<T>(
(Ref ref) => factory(ref, args),
debugLabel: '${debugLabel ?? 'FutureFamily'}<$args>',
),
);
}
@override
PodElement<AsyncValue<T>> createElement() => _FuturePodElement(this);
}
@optionalTypeArgs
final class StreamPod<T> extends _AsyncValuePod<T, Stream<T>> {
StreamPod(super._factory, {super.debugLabel});
static ValueMapper<U, StreamPod<T>> family<T, U>(
FamilyPodFactory<Stream<T>, U> factory, {
String? debugLabel,
}) {
return Pod._family(
(U args) => StreamPod<T>(
(Ref ref) => factory(ref, args),
debugLabel: '${debugLabel ?? 'StreamFamily'}<$args>',
),
);
}
@override
PodElement<AsyncValue<T>> createElement() => _StreamPodElement(this);
}
/* End Pod Types */
/* Start Internal Pod Types */
@optionalTypeArgs
final class _ProxyPod<T> extends Pod<T> with WatchablePod<T> {
const _ProxyPod(this._builder, {required super.debugLabel});
final PodFactory<T> _builder;
@override
PodElement<T> createElement() => _ProxyPodElement(_builder);
}
@optionalTypeArgs
final class _SelectorPod<T> extends _ProxyPod<T> with NotifiablePod<T> {
const _SelectorPod(super._builder, {super.debugLabel});
}
@optionalTypeArgs
final class _AsyncSelectorPod<T, U, V> extends Pod<Future<U>> with NotifiablePod<Future<U>> {
const _AsyncSelectorPod(this._factory, this._selector, {super.debugLabel});
final PodFactory<V> _factory;
final ValueMapper<T, U> _selector;
@override
PodElement<Future<U>> createElement() => _AsyncSelectorPodElement<T, U, V>(_factory, _selector);
}
@optionalTypeArgs
abstract base class _AsyncValuePod<T, U> extends Pod<AsyncValue<T>> implements AsyncPod<T, U> {
_AsyncValuePod(this._factory, {super.debugLabel});
@override
final PodFactory<U> _factory;
Completer<T>? _completer;
@override
late final WatchablePod<Future<T>> future = _AsyncSelectorPod<T, T, Future<T>>(
(Ref ref) {
if (_completer?.isCompleted == true) {
_completer = null;
}
_completer ??= Completer<T>.sync();
final T? value = ref.watch(this).previousValue;
if (value != null) {
_completer?.complete(value);
}
(ref as Pods)._owner._dependents.whereType<_AsyncValuePodElement>().forEach(
(_) => _._refreshState(),
);
return _completer!.future;
},
(T value) => value,
debugLabel: 'Future<$this>',
);
}
/* End Internal Pod Types */
/* Start Pod Elements */
final class _AnonymousPodElement extends PodElement<Object> {
_AnonymousPodElement() : super(Object());
}
@optionalTypeArgs
final class _ValuePodElement<T> extends PodElement<T> {
_ValuePodElement(this._pod);
final ValuePod<T> _pod;
@override
void mount(Ref ref) {
_state = _pod._factory(ref);
super.mount(ref);
}
}
@optionalTypeArgs
base class _AsyncValuePodElement<T, U> extends PodElement<AsyncValue<T>> {
_AsyncValuePodElement(_AsyncValuePod<T, U> pod) : _factory = pod._factory;
final PodFactory<U> _factory;
@override
void mount(Ref ref) {
_refreshState();
super.mount(ref);
}
void _refreshState() => state = PendingAsyncValue(_state?.previousValue);
}
@optionalTypeArgs
final class _FuturePodElement<T> extends _AsyncValuePodElement<T, FutureOr<T>> {
_FuturePodElement(super._pod);
@override
void mount(Ref ref) {
Future<T>.value(_factory(ref)).then((T value) {
state = SuccessfulAsyncValue(value);
}).catchError((Object error, StackTrace stackTrace) {
state = FailedAsyncValue(error, stackTrace);
});
super.mount(ref);
}
}
@optionalTypeArgs
final class _StreamPodElement<T> extends _AsyncValuePodElement<T, Stream<T>> {
_StreamPodElement(super._pod);
StreamSubscription<T>? _subscription;
@override
void mount(Ref ref) {
_subscription?.cancel();
_subscription = _factory(ref).listen((T value) {
state = SuccessfulAsyncValue(value);
}, onError: (Object error, StackTrace stackTrace) {
state = FailedAsyncValue(error, stackTrace);
});
super.mount(ref);
}
@override
void dispose() {
_subscription?.cancel();
super.dispose();
}
}
@optionalTypeArgs
final class _ProxyPodElement<T> extends PodElement<T> {
_ProxyPodElement(this._builder);
final PodFactory<T> _builder;
@override
void mount(Pods ref) {
state = _builder(ref);
super.mount(ref);
}
}
@optionalTypeArgs
final class _AsyncSelectorPodElement<T, U, V> extends PodElement<Future<U>> {
_AsyncSelectorPodElement(this._factory, this._selector);
final PodFactory<V> _factory;
final ValueMapper<T, U> _selector;
final StreamController<T> _controller = StreamController<T>.broadcast();
final Completer<U> _completer = Completer<U>();
StreamSubscription<U>? _subscription;
StreamSubscription<T>? _innerSubscription;
@override
void mount(Ref ref) {
_subscription ??= _controller.stream.map(_selector).distinct().listen((U value) {
state = Future<U>.value(value);
if (!_completer.isCompleted) {
_completer.complete(value);
}
});
switch (_factory(ref)) {
case T value:
_controller.add(value);
case Future<T> future:
future.then(_controller.add);
case Stream<T> stream:
_innerSubscription?.cancel();
_innerSubscription = stream.listen(_controller.add);
}
_state = _completer.future;
super.mount(ref);
}
@override
void dispose() {
_state?.ignore();
_innerSubscription?.cancel();
_subscription?.cancel();
_controller.close();
super.dispose();
}
}
/* End Pod Elements */
/* Start Data Classes */
@optionalTypeArgs
class Notifier<T> {
Notifier(this._stateFn, this._listener);
final ValueCallback<T> _stateFn;
final ValueMapper<T, void> _listener;
@protected
T get state => _stateFn();
set state(T value) => _listener(value);
T update(ValueMapper<T, T> cb) => state = cb(_stateFn());
@override
String toString() => 'Notifier<${_stateFn()}>';
}
@optionalTypeArgs
sealed class AsyncValue<T> {}
@optionalTypeArgs
class PendingAsyncValue<T> implements AsyncValue<T> {
const PendingAsyncValue(this.data);
final T? data;
@override
bool operator ==(Object other) =>
identical(this, other) || other is PendingAsyncValue<T> && runtimeType == other.runtimeType && data == other.data;
@override
int get hashCode => data.hashCode;
@override
String toString() => 'PendingAsyncValue${data != null ? '<$data>' : ''}';
}
@optionalTypeArgs
class SuccessfulAsyncValue<T> implements AsyncValue<T> {
const SuccessfulAsyncValue(this.data);
final T data;
@override
bool operator ==(Object other) =>
identical(this, other) ||
other is SuccessfulAsyncValue<T> && runtimeType == other.runtimeType && data == other.data;
@override
int get hashCode => data.hashCode;
@override
String toString() => 'SuccessfulAsyncValue<$data>';
}
@optionalTypeArgs
class FailedAsyncValue<T> implements AsyncValue<T> {
const FailedAsyncValue(this.error, this.stackTrace);
final Object error;
final StackTrace stackTrace;
@override
bool operator ==(Object other) =>
identical(this, other) ||
other is FailedAsyncValue<T> && runtimeType == other.runtimeType && error == other.error;
@override
int get hashCode => error.hashCode;
@override
String toString() => 'FailedAsyncValue<$error>';
}
extension<T> on AsyncValue<T> {
T? get previousValue => switch (this) {
PendingAsyncValue<T> state => state.data,
SuccessfulAsyncValue<T> state => state.data,
FailedAsyncValue<T> _ => null,
};
}
/* End Data Classes */
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