init

Author: Nguyễn Thái Học

.gitignore

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+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+.dart_tool/
+.flutter-plugins
+.flutter-plugins-dependencies
+.packages
+.pub-cache/
+.pub/
+build/
+
+# Android related
+**/android/**/gradle-wrapper.jar
+**/android/.gradle
+**/android/captures/
+**/android/gradlew
+**/android/gradlew.bat
+**/android/local.properties
+**/android/**/GeneratedPluginRegistrant.java
+
+# iOS/XCode related
+**/ios/**/*.mode1v3
+**/ios/**/*.mode2v3
+**/ios/**/*.moved-aside
+**/ios/**/*.pbxuser
+**/ios/**/*.perspectivev3
+**/ios/**/*sync/
+**/ios/**/.sconsign.dblite
+**/ios/**/.tags*
+**/ios/**/.vagrant/
+**/ios/**/DerivedData/
+**/ios/**/Icon?
+**/ios/**/Pods/
+**/ios/**/.symlinks/
+**/ios/**/profile
+**/ios/**/xcuserdata
+**/ios/.generated/
+**/ios/Flutter/App.framework
+**/ios/Flutter/Flutter.framework
+**/ios/Flutter/Flutter.podspec
+**/ios/Flutter/Generated.xcconfig
+**/ios/Flutter/app.flx
+**/ios/Flutter/app.zip
+**/ios/Flutter/flutter_assets/
+**/ios/Flutter/flutter_export_environment.sh
+**/ios/ServiceDefinitions.json
+**/ios/Runner/GeneratedPluginRegistrant.*
+
+# Exceptions to above rules.
+!**/ios/**/default.mode1v3
+!**/ios/**/default.mode2v3
+!**/ios/**/default.pbxuser
+!**/ios/**/default.perspectivev3

.metadata

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+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: 022b333a089afb81c471ec43d1f1f4f26305d876
+  channel: dev
+
+project_type: package

CHANGELOG.md

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+## [0.0.1] - TODO: Add release date.
+
+* TODO: Describe initial release.

LICENSE

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+TODO: Add your license here.

README.md

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+# listenable_stream
+
+listenable_stream
+
+## Getting Started
+
+This project is a starting point for a Dart
+[package](https://flutter.dev/developing-packages/),
+a library module containing code that can be shared easily across
+multiple Flutter or Dart projects.
+
+For help getting started with Flutter, view our 
+[online documentation](https://flutter.dev/docs), which offers tutorials, 
+samples, guidance on mobile development, and a full API reference.

analysis_options.yaml

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+include: package:pedantic/analysis_options.1.9.0.yaml
+linter:
+  rules:
+    - prefer_final_locals
+    - prefer_relative_imports
+    - public_member_api_docs

lib/listenable_stream.dart

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+library listenable_stream;
+
+export './src/listenable_to_stream.dart';
+export './src/value_listenable_to_value_stream.dart';

lib/src/listenable_to_stream.dart

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+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+
+/// Convert this [Listenable] to a [Stream].
+extension ListenableToStream<T extends Listenable> on T {
+  /// Convert this [Listenable] to a [Stream].
+  Stream<T> toStream() {
+    StreamController<T> controller;
+    VoidCallback listener;
+
+    controller = StreamController<T>(
+      sync: true,
+      onListen: () => addListener(listener = () => controller.add(this)),
+      onCancel: () {
+        try {
+          removeListener(listener);
+          listener = null;
+        } catch (_) {}
+      },
+    );
+
+    return controller.stream;
+  }
+}

lib/src/value_listenable_to_value_stream.dart

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+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+import 'package:rxdart/rxdart.dart';
+
+import 'listenable_to_stream.dart';
+
+/// Convert this [ValueListenable] to a [ValueStream].
+/// The returned [ValueStream] is a Single-Subscription [Stream].
+///
+/// If [replayValue] is true, the returned [ValueStream] will replay latest value when listening to it.
+/// Otherwise, it does not.
+extension ValueListenableToValueStream<T> on ValueListenable<T> {
+  /// Convert this [ValueListenable] to a [ValueStream].
+  /// The returned [ValueStream] is a Single-Subscription [Stream].
+  ///
+  /// If [replayValue] is true, the returned [ValueStream] will replay latest value when listening to it.
+  /// Otherwise, it does not.
+  ValueStream<T> toValueStream({bool replayValue = false}) =>
+      ValueListenableStream<T>(this, replayValue);
+}
+
+/// A Single-Subscription Stream will emits data when [ValueListenable.value] changed.
+class ValueListenableStream<T> extends Stream<T> implements ValueStream<T> {
+  final ValueListenable<T> _valueListenable;
+  final bool _replayValue;
+  Stream<T> _stream;
+
+  /// Construct a [ValueListenableStream] from [ValueListenable].
+  ValueListenableStream(this._valueListenable, this._replayValue);
+
+  @override
+  bool get isBroadcast => false;
+
+  @override
+  ErrorAndStackTrace get errorAndStackTrace => null;
+
+  @override
+  bool get hasError => false;
+
+  @override
+  bool get hasValue => true;
+
+  @override
+  T get value => _valueListenable.value;
+
+  @override
+  StreamSubscription<T> listen(
+    void Function(T) onData, {
+    Function onError,
+    void Function() onDone,
+    bool cancelOnError,
+  }) {
+    if (_replayValue) {
+      _stream ??= _valueListenable
+          .toStream()
+          .map((_) => _valueListenable.value)
+          .shareBehavior(value);
+    } else {
+      _stream ??=
+          _valueListenable.toStream().map((_) => _valueListenable.value);
+    }
+
+    return _stream.listen(
+      onData,
+      onError: onError,
+      onDone: onDone,
+      cancelOnError: cancelOnError,
+    );
+  }
+}
+
+extension _ShareValueExtension<T> on Stream<T> {
+  Stream<T> shareBehavior(T seeded) {
+    final controllers = <MultiStreamController<T>>[];
+    StreamSubscription<T> subscription;
+
+    var latestValue = seeded;
+    var cancel = false;
+    var done = false;
+
+    final listenUpStream = () => listen(
+          (event) {
+            latestValue = event;
+            controllers.forEach((c) => c.addSync(event));
+          },
+          onError: (e, StackTrace st) =>
+              controllers.forEach((c) => c.addErrorSync(e, st)),
+          onDone: () {
+            done = true;
+            subscription = null;
+
+            controllers.forEach((c) {
+              c.onCancel = null;
+              c.closeSync();
+            });
+            controllers.clear();
+          },
+        );
+
+    final onListen = (MultiStreamController<T> controller) {
+      if (cancel) {
+        return controller.closeSync();
+      }
+      controller.addSync(latestValue);
+      if (done) {
+        return controller.closeSync();
+      }
+
+      final wasEmpty = controllers.isEmpty;
+      controllers.add(controller);
+      if (wasEmpty) {
+        subscription = listenUpStream();
+      }
+
+      controller.onCancel = () {
+        controllers.remove(controller);
+        if (controllers.isEmpty) {
+          subscription?.cancel();
+          subscription = null;
+          cancel = true;
+        }
+      };
+    };
+
+    return Stream.multi(onListen, isBroadcast: true);
+  }
+}