Create Flutter adapter for GenUiValueNotifier.

packages/a2ui_core/lib/a2ui_core.dart

@@ -5,5 +5,9 @@
 export 'src/listenable/error_reporting.dart'
     show ListenableError, ListenableErrorDetails;
 export 'src/listenable/notifiers.dart'
-    show ChangeNotifier, GenUiListenable, GenUiValueListenable, ValueNotifier;
+    show
+        GenUiChangeNotifier,
+        GenUiListenable,
+        GenUiValueListenable,
+        GenUiValueNotifier;
 export 'src/listenable/primitives.dart' show VoidCallback;

packages/a2ui_core/lib/src/listenable/notifiers.dart

@@ -65,7 +65,7 @@ abstract class GenUiValueListenable<T> extends GenUiListenable {
 ///
 /// This class should not be modified, because it is temporary and should be
 /// replaced with dash-wide alternative.
-mixin class ChangeNotifier implements GenUiListenable {
+mixin class GenUiChangeNotifier implements GenUiListenable {
   int _count = 0;
   // The _listeners is intentionally set to a fixed-length _GrowableList instead
   // of const [].
@@ -84,8 +84,8 @@ mixin class ChangeNotifier implements GenUiListenable {
   int _reentrantlyRemovedListeners = 0;
   bool _debugDisposed = false;
 
-  /// Used by subclasses to assert that the [ChangeNotifier] has not yet been
-  /// disposed.
+  /// Used by subclasses to assert that the [GenUiChangeNotifier] has not
+  /// yet been disposed.
   ///
   /// {@tool snippet}
   /// The [debugAssertNotDisposed] function should only be called inside of an
@@ -103,7 +103,7 @@ mixin class ChangeNotifier implements GenUiListenable {
   // This is static and not an instance method because too many people try to
   // implement ChangeNotifier instead of extending it (and so it is too breaking
   // to add a method, especially for debug).
-  static bool debugAssertNotDisposed(ChangeNotifier notifier) {
+  static bool debugAssertNotDisposed(GenUiChangeNotifier notifier) {
     assert(() {
       if (notifier._debugDisposed) {
         throw ListenableErrorReporting.createError(
@@ -150,7 +150,7 @@ mixin class ChangeNotifier implements GenUiListenable {
   /// (e.g. in response to a notification), it will still be called again. If,
   /// on the other hand, it is removed as many times as it was registered, then
   /// it will no longer be called. This odd behavior is the result of the
-  /// [ChangeNotifier] not being able to determine which listener is being
+  /// [GenUiChangeNotifier] not being able to determine which listener is being
   /// removed, since they are identical, therefore it will conservatively still
   /// call all the listeners when it knows that any are still registered.
   ///
@@ -165,7 +165,7 @@ mixin class ChangeNotifier implements GenUiListenable {
   ///    the list of closures that are notified when the object changes.
   @override
   void addListener(VoidCallback listener) {
-    assert(ChangeNotifier.debugAssertNotDisposed(this));
+    assert(GenUiChangeNotifier.debugAssertNotDisposed(this));
 
     if (_count == _listeners.length) {
       if (_count == 0) {
@@ -269,7 +269,7 @@ mixin class ChangeNotifier implements GenUiListenable {
   /// listeners or not immediately before disposal.
   @mustCallSuper
   void dispose() {
-    assert(ChangeNotifier.debugAssertNotDisposed(this));
+    assert(GenUiChangeNotifier.debugAssertNotDisposed(this));
     if (_notificationCallStackDepth > 0) {
       throw ListenableErrorReporting.createError(
         'The "dispose()" method on $this was called during the call to '
@@ -304,7 +304,7 @@ mixin class ChangeNotifier implements GenUiListenable {
   @visibleForTesting
   @pragma('vm:notify-debugger-on-exception')
   void notifyListeners() {
-    assert(ChangeNotifier.debugAssertNotDisposed(this));
+    assert(GenUiChangeNotifier.debugAssertNotDisposed(this));
     if (_count == 0) {
       return;
     }
@@ -403,16 +403,16 @@ class _MergingListenable extends GenUiListenable {
   }
 }
 
-/// A [ChangeNotifier] that holds a single value.
+/// A [GenUiChangeNotifier] that holds a single value.
 ///
 /// Dart replica of Flutter's [ValueNotifier](https://api.flutter.dev/flutter/foundation/ValueNotifier-class.html)
 ///
 /// This class should not be modified, because it is temporary and should be
 /// replaced with dash-wide alternative.
-class ValueNotifier<T> extends ChangeNotifier
+class GenUiValueNotifier<T> extends GenUiChangeNotifier
     implements GenUiValueListenable<T> {
-  /// Creates a [ChangeNotifier] that wraps this value.
-  ValueNotifier(this._value);
+  /// Creates a [GenUiChangeNotifier] that wraps this value.
+  GenUiValueNotifier(this._value);
 
   /// The current value stored in this notifier.
   ///

packages/a2ui_core/test/listenable/listenable_test.dart

@@ -6,15 +6,15 @@ import 'package:a2ui_core/a2ui_core.dart';
 import 'package:a2ui_core/src/listenable/error_reporting.dart';
 import 'package:test/test.dart';
 
-class TestNotifier extends ChangeNotifier {
+class TestNotifier extends GenUiChangeNotifier {
   void notify() {
     notifyListeners();
   }
 
   bool get isListenedTo => hasListeners;
 }
 
-class HasListenersTester<T> extends ValueNotifier<T> {
+class HasListenersTester<T> extends GenUiValueNotifier<T> {
   HasListenersTester(super.value);
   bool get testHasListeners => hasListeners;
 }
@@ -26,7 +26,7 @@ class A {
   }
 }
 
-class B extends A with ChangeNotifier {
+class B extends A with GenUiChangeNotifier {
   B();
 
   @override
@@ -36,7 +36,7 @@ class B extends A with ChangeNotifier {
   }
 }
 
-class Counter with ChangeNotifier {
+class Counter with GenUiChangeNotifier {
   Counter();
 
   int get value => _value;
@@ -377,7 +377,7 @@ void main() {
   });
 
   test('Value notifier', () {
-    final notifier = ValueNotifier<double>(2.0);
+    final notifier = GenUiValueNotifier<double>(2.0);
 
     final log = <double>[];
     void listener() {
@@ -512,11 +512,11 @@ void main() {
 
   test('Calling debugAssertNotDisposed works as intended', () {
     final testNotifier = TestNotifier();
-    expect(ChangeNotifier.debugAssertNotDisposed(testNotifier), isTrue);
+    expect(GenUiChangeNotifier.debugAssertNotDisposed(testNotifier), isTrue);
     testNotifier.dispose();
     ListenableError? error;
     try {
-      ChangeNotifier.debugAssertNotDisposed(testNotifier);
+      GenUiChangeNotifier.debugAssertNotDisposed(testNotifier);
       // ignore: avoid_catching_errors
     } on ListenableError catch (e) {
       error = e;

packages/a2ui_core/test/listenable/smoke_test.dart

@@ -6,7 +6,7 @@ import 'package:a2ui_core/a2ui_core.dart';
 import 'package:test/test.dart';
 
 // ignore: unused_element, tests that ValueNotifier can be implemented.
-class _ValueNotifierImplementation<T> implements ValueNotifier<T> {
+class _ValueNotifierImplementation<T> implements GenUiValueNotifier<T> {
   @override
   void addListener(VoidCallback listener) {}
 
@@ -30,12 +30,12 @@ class _ValueNotifierImplementation<T> implements ValueNotifier<T> {
 }
 
 // ignore: unused_element, tests that ValueNotifier can be extended.
-class _ValueNotifierExtension<T> extends ValueNotifier<T> {
+class _ValueNotifierExtension<T> extends GenUiValueNotifier<T> {
   _ValueNotifierExtension(super.value);
 }
 
 // ignore: unused_element, tests that ChangeNotifier can be implemented.
-class _ChangeNotifierImplementation implements ChangeNotifier {
+class _ChangeNotifierImplementation implements GenUiChangeNotifier {
   @override
   void addListener(VoidCallback listener) {}
 
@@ -53,11 +53,11 @@ class _ChangeNotifierImplementation implements ChangeNotifier {
 }
 
 // ignore: unused_element, tests that ChangeNotifier can be extended.
-class _ChangeNotifierExtention extends ChangeNotifier {}
+class _ChangeNotifierExtention extends GenUiChangeNotifier {}
 
 void main() {
   test('ValueNotifier basic functionality is working', () {
-    final ValueNotifier<int> notifier = ValueNotifier(1);
+    final GenUiValueNotifier<int> notifier = GenUiValueNotifier(1);
     addTearDown(notifier.dispose);
     var count = 0;
     notifier.addListener(() => count++);
@@ -72,7 +72,7 @@ void main() {
   });
 
   test('ChangeNotifier basic functionality is working', () {
-    final notifier = ChangeNotifier();
+    final notifier = GenUiChangeNotifier();
     addTearDown(notifier.dispose);
     var count = 0;
     notifier.addListener(() => count++);

packages/genui/lib/src/primitives/flutter_listenable.dart

@@ -0,0 +1,50 @@
+// Copyright 2025 The Flutter Authors.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:a2ui_core/a2ui_core.dart';
+import 'package:flutter/foundation.dart';
+
+/// Extension to convert [GenUiListenable] to [Listenable].
+///
+/// Enables using [GenUiListenable] with Flutter widgets
+/// that accept [Listenable].
+extension FlutterListenable on GenUiListenable {
+  Listenable listenable() {
+    return FlutterListenableAdapter(this);
+  }
+}
+
+/// Extensions to convert GenUi value listenables to Flutter value listenables.
+extension GenUiValueListenableFlutterExtension<T> on GenUiValueListenable<T> {
+  /// Converts this [GenUiValueListenable] to a Flutter [ValueListenable].
+  ValueListenable<T> valueListenable() =>
+      FlutterValueListenableAdapter<T>(this);
+}
+
+class FlutterListenableAdapter implements Listenable {
+  FlutterListenableAdapter(this._listenable);
+
+  final GenUiListenable _listenable;
+
+  @override
+  void addListener(VoidCallback listener) {
+    _listenable.addListener(listener);
+  }
+
+  @override
+  void removeListener(VoidCallback listener) {
+    _listenable.removeListener(listener);
+  }
+}
+
+class FlutterValueListenableAdapter<T> extends FlutterListenableAdapter
+    implements ValueListenable<T> {
+  FlutterValueListenableAdapter(GenUiValueListenable<T> super.listenable);
+
+  GenUiValueListenable<T> get _valueListenable =>
+      _listenable as GenUiValueListenable<T>;
+
+  @override
+  T get value => _valueListenable.value;
+}

packages/genui/pubspec.yaml

@@ -16,6 +16,7 @@ environment:
 resolution: workspace
 
 dependencies:
+  a2ui_core: ^0.0.1-dev001
   audioplayers: ^6.6.0
   collection: ^1.19.1
   flutter:

packages/genui/test/primitives/flutter_listenable_test.dart

@@ -0,0 +1,77 @@
+// Copyright 2025 The Flutter Authors.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:a2ui_core/a2ui_core.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:genui/src/primitives/flutter_listenable.dart';
+
+class TestGenUiListenable extends GenUiListenable {
+  int addListenerCount = 0;
+  int removeListenerCount = 0;
+  VoidCallback? lastAddedListener;
+  VoidCallback? lastRemovedListener;
+
+  @override
+  void addListener(VoidCallback listener) {
+    addListenerCount++;
+    lastAddedListener = listener;
+  }
+
+  @override
+  void removeListener(VoidCallback listener) {
+    removeListenerCount++;
+    lastRemovedListener = listener;
+  }
+}
+
+class TestGenUiValueListenable<T> extends TestGenUiListenable
+    implements GenUiValueListenable<T> {
+  TestGenUiValueListenable(this.value);
+
+  @override
+  T value;
+}
+
+void main() {
+  group('FlutterListenable', () {
+    test('adapter registers and unregisters listeners correctly', () {
+      final listenable = TestGenUiListenable();
+      final Listenable adapter = listenable.listenable();
+
+      expect(adapter, isA<Listenable>());
+      expect(adapter, isA<FlutterListenableAdapter>());
+
+      void listener() {}
+
+      adapter.addListener(listener);
+      expect(listenable.addListenerCount, 1);
+      expect(listenable.lastAddedListener, listener);
+
+      adapter.removeListener(listener);
+      expect(listenable.removeListenerCount, 1);
+      expect(listenable.lastRemovedListener, listener);
+    });
+
+    test('valueListenable adapter works correctly', () {
+      final valueListenable = TestGenUiValueListenable<int>(42);
+      final ValueListenable<int> adapter = valueListenable.valueListenable();
+
+      expect(adapter, isA<ValueListenable<int>>());
+      expect(adapter, isA<FlutterValueListenableAdapter<int>>());
+
+      expect(adapter.value, 42);
+
+      void listener() {}
+
+      adapter.addListener(listener);
+      expect(valueListenable.addListenerCount, 1);
+      expect(valueListenable.lastAddedListener, listener);
+
+      adapter.removeListener(listener);
+      expect(valueListenable.removeListenerCount, 1);
+      expect(valueListenable.lastRemovedListener, listener);
+    });
+  });
+}