Init repo

lib/util/stream_value.dart

@@ -0,0 +1,38 @@
+import 'dart:async';
+
+class StreamValue<T> {
+  final T _initialValue;
+  T _latestValue;
+  final StreamController<T> _controller;
+  bool _hasInitialValue = true;
+
+  StreamValue(T initialValue)
+      : _initialValue = initialValue,
+        _latestValue = initialValue,
+        _controller = StreamController<T>.broadcast();
+
+  Stream<T> get stream => _controller.stream;
+
+  void add(T value) {
+    _latestValue = value;
+    _hasInitialValue = false;
+    _controller.add(value);
+  }
+
+  void addError(Object error, [StackTrace? stackTrace]) {
+    _controller.addError(error, stackTrace);
+  }
+
+  void listen(void Function(T) onData, {Function? onError, void Function()? onDone, bool? cancelOnError}) {
+    if (_hasInitialValue) {
+      onData(_initialValue);
+    } else {
+      onData(_latestValue);
+    }
+    _controller.stream.listen(onData, onError: onError, onDone: onDone, cancelOnError: cancelOnError);
+  }
+
+  void close() {
+    _controller.close();
+  }
+}