feat: allow a custom equals parameter for ObservableStream

Signed-off-by: Minsu Lee <[email protected]>

Author: amondnet

docs/docs/api/observable.mdx

@@ -268,12 +268,15 @@ class LoadingIndicator extends StatelessWidget {
 
 ## ObservableStream
 
-#### `ObservableStream(Stream<T> stream, {T initialValue, bool cancelOnError, ReactiveContext context})`
+#### `ObservableStream(Stream<T> stream, {T initialValue, bool cancelOnError, ReactiveContext context, String? name,
+      EqualityComparer<dynamic>? equals})`
 
 - **`Stream<T> stream`**: The stream that is tracked for `status` and `value` changes.
 - **`T initialValue`**: The starting value of the stream.
 - **`bool cancelOnError`**: Should the stream be cancelled on error. Default is set to `false`.
 - **`ReactiveContext context`**: the context to which this observable-stream is bound. By default, all `ObservableStream`s are bound to the singleton `mainContext` of the application.
+- **`String? name`**: This string is used as a debug name.
+- **`EqualityComparer<dynamic>? equals`**: It acts as a comparison function for comparing the previous value with the next value. If this function considers the values to be equal, then the observers will not be re-evaluated.
 
 Similar to `ObservableFuture`, an **`ObservableStream`** provides a reactive wrapper around a `Stream`. This gives an easy way to observe and re-render whenever there is new `data`, or `error` or a `status` change on the `ObservableStream`.
 

mobx/lib/src/api/async/observable_stream.dart

@@ -36,6 +36,8 @@ class ObservableStream<T> implements Stream<T>, ObservableValue<T?> {
   ///
   /// If `cancelOnError` is `true`, the stream will be cancelled when an error
   /// event is emitted by the source stream. The default value is `false`.
+  ///
+  /// It is possible to override equality comparison of new values with [equals].
   ObservableStream(Stream<T> stream,
       {T? initialValue,
       bool cancelOnError = false,