add class modifiers (#113)

lib/src/not_replay_value_stream/not_replay_value_connectable_stream.dart

@@ -13,8 +13,9 @@ import 'value_subject.dart';
 /// a broadcast [Stream], and provides synchronous access to the latest emitted value.
 ///
 /// See [NotReplayValueStream].
-class NotReplayValueConnectableStream<T> extends AbstractConnectableStream<T,
-        ValueSubject<T>, NotReplayValueStream<T>>
+final class NotReplayValueConnectableStream<T>
+    extends AbstractConnectableStream<T, ValueSubject<T>,
+        NotReplayValueStream<T>>
     with NotReplayValueStreamMixin<T>
     implements NotReplayValueStream<T> {
   final ValueSubject<T> _subject;

lib/src/not_replay_value_stream/not_replay_value_stream.dart

@@ -3,4 +3,4 @@ import 'package:rxdart/rxdart.dart' show ValueStream;
 /// The marker interface for [ValueStream] classes
 /// that provide synchronous access to the last emitted item,
 /// but do not replay the latest value.
-abstract class NotReplayValueStream<T> extends ValueStream<T> {}
+abstract interface class NotReplayValueStream<T> implements ValueStream<T> {}

lib/src/not_replay_value_stream/stream_event.dart

@@ -3,7 +3,7 @@ import 'package:rxdart/rxdart.dart' show ErrorAndStackTrace;
 
 /// Class that holds latest value and lasted error emitted from Stream.
 @internal
-class StreamEvent<T> {
+final class StreamEvent<T> {
   T _value;
   ErrorAndStackTrace? _errorAndStacktrace;
   var _lastEventIsData = false;

lib/src/not_replay_value_stream/value_stream_controller.dart

@@ -21,7 +21,7 @@ import 'stream_event.dart';
 /// it has subscribers or not, as well as getting a callback when either of
 /// these change.
 @sealed
-class ValueStreamController<T> implements StreamController<T> {
+final class ValueStreamController<T> implements StreamController<T> {
   final StreamController<T> _delegate;
   final StreamEvent<T> _dataOrError;
 

lib/src/not_replay_value_stream/value_subject.dart

@@ -33,7 +33,7 @@ import 'stream_event.dart';
 ///     subject.add(2);
 ///     subject.close();
 @sealed
-class ValueSubject<T> extends Subject<T>
+final class ValueSubject<T> extends Subject<T>
     with NotReplayValueStreamMixin<T>
     implements NotReplayValueStream<T> {
   final StreamEvent<T> _dataOrError;

lib/src/operators/done_on_error.dart

@@ -2,7 +2,7 @@ import 'dart:async';
 
 import '../utils/default_sink.dart';
 
-class _DoneOnErrorSink<T> extends BaseEventSink<T, T> {
+final class _DoneOnErrorSink<T> extends BaseEventSink<T, T> {
   final bool Function(Object e, StackTrace s) predicate;
 
   _DoneOnErrorSink(super.sink, this.predicate);

lib/src/operators/ignore.dart

@@ -2,7 +2,7 @@ import 'dart:async';
 
 import '../utils/default_sink.dart';
 
-class _IgnoreErrorsEventSink<T> extends BaseEventSink<T, T> {
+final class _IgnoreErrorsEventSink<T> extends BaseEventSink<T, T> {
   _IgnoreErrorsEventSink(super.sink);
 
   @override

lib/src/operators/void.dart

@@ -2,7 +2,7 @@ import 'dart:async';
 
 import '../utils/default_sink.dart';
 
-class _AsVoidStreamSink<T> extends BaseEventSink<T, void> {
+final class _AsVoidStreamSink<T> extends BaseEventSink<T, void> {
   _AsVoidStreamSink(super.sink);
 
   @override

lib/src/single/on_error_resume.dart

@@ -3,7 +3,7 @@ import 'dart:async';
 import '../utils/default_sink.dart';
 import 'single.dart';
 
-class _OnErrorReturnSingleSink<T> extends BaseEventSink<T, T> {
+final class _OnErrorReturnSingleSink<T> extends BaseEventSink<T, T> {
   final T returnValue;
 
   _OnErrorReturnSingleSink(super.sink, this.returnValue);
@@ -16,7 +16,7 @@ class _OnErrorReturnSingleSink<T> extends BaseEventSink<T, T> {
       sink.add(returnValue);
 }
 
-class _OnErrorReturnWithSingleSink<T> extends BaseEventSink<T, T> {
+final class _OnErrorReturnWithSingleSink<T> extends BaseEventSink<T, T> {
   final T Function(Object error, StackTrace stackTrace) itemSupplier;
 
   _OnErrorReturnWithSingleSink(super.sink, this.itemSupplier);

lib/src/single/single.dart

@@ -18,7 +18,7 @@ import 'internal.dart';
 ///                         error done
 /// ```
 @sealed
-class Single<T> extends StreamView<T> {
+final class Single<T> extends StreamView<T> {
   /// Underline source Stream.
   final Stream<T> _stream;
 
@@ -179,7 +179,7 @@ class Single<T> extends StreamView<T> {
       Single.safe(_stream.asyncMap(convert));
 }
 
-class _SingleOrErrorStreamSink<T> extends BaseEventSink<T, T> {
+final class _SingleOrErrorStreamSink<T> extends BaseEventSink<T, T> {
   var value = _null;
   ErrorAndStackTrace? error;
 

lib/src/state_stream/state_connectable_stream.dart

@@ -12,7 +12,7 @@ import 'state_subject.dart';
 ///
 /// This is a combination of [ConnectableStream], [ValueStream], [ValueSubject] and [Stream.distinct].
 @sealed
-abstract class StateConnectableStream<T> extends ConnectableStream<T>
+sealed class StateConnectableStream<T> extends ConnectableStream<T>
     implements StateStream<T> {
   /// Constructs a [Stream] which only begins emitting events when
   /// the [connect] method is called, this [Stream] acts like a
@@ -44,7 +44,7 @@ abstract class StateConnectableStream<T> extends ConnectableStream<T>
   StateStream<T> refCount();
 }
 
-class _StateConnectableStream<T>
+final class _StateConnectableStream<T>
     extends AbstractConnectableStream<T, StateSubject<T>, StateStream<T>>
     with StateStreamMixin<T>
     implements StateConnectableStream<T> {

lib/src/state_stream/state_stream.dart

@@ -17,7 +17,7 @@ export '../utils/equality.dart';
 ///
 /// This [Stream] do **not replay** the latest value, see [NotReplayValueStream].
 /// This [Stream] always has **no error**.
-abstract class StateStream<T> extends NotReplayValueStream<T> {
+abstract interface class StateStream<T> implements NotReplayValueStream<T> {
   /// Determined equality between previous data event and current data event.
   Equality<T> get equals;
 
@@ -56,7 +56,7 @@ abstract class StateStream<T> extends NotReplayValueStream<T> {
 }
 
 /// A mutable [StateStream] that provides a setter for [value].
-abstract class MutableStateStream<T> implements StateStream<T> {
+abstract interface class MutableStateStream<T> implements StateStream<T> {
   /// Set the [value] of this [MutableStateStream].
   /// Also emits the [newValue] to all listeners
   /// if it is not equal to the current value.

lib/src/state_stream/state_subject.dart

@@ -50,7 +50,7 @@ import 'state_stream_mixin.dart';
 ///     subject.add(3);
 ///     subject.close();
 @sealed
-class StateSubject<T> extends Subject<T>
+final class StateSubject<T> extends Subject<T>
     with StateStreamMixin<T>
     implements StateStream<T>, MutableStateStream<T> {
   T _value;

lib/src/utils/default_sink.dart

@@ -21,7 +21,7 @@ mixin ForwardingSinkMixin<T, R> implements ForwardingSink<T, R> {
 }
 
 /// This [EventSink] class implements all [EventSink] members except [add].
-abstract class BaseEventSink<T, R> implements EventSink<T> {
+abstract base class BaseEventSink<T, R> implements EventSink<T> {
   /// The output sink.
   @protected
   final EventSink<R> sink;

lib/src/utils/stream_sink_wrapper.dart

@@ -4,7 +4,7 @@ import 'package:meta/meta.dart';
 
 /// A class that exposes only the [StreamSink] interface of an object.
 @internal
-class StreamSinkWrapper<T> implements StreamSink<T> {
+final class StreamSinkWrapper<T> implements StreamSink<T> {
   final StreamSink<T> _target;
 
   /// Creates a [StreamSinkWrapper] that wraps [target].