feat(ui): add possibility to limit attachments in MessageInput

Signed-off-by: xsahil03x <[email protected]>

packages/stream_chat_flutter/lib/src/utils.dart

@@ -340,3 +340,51 @@ Widget wrapAttachmentWidget(
       type: MaterialType.transparency,
       child: attachmentWidget,
     );
+
+/// Represents a 2-tuple, or pair.
+class Tuple2<T1, T2> {
+  /// Creates a new tuple value with the specified items.
+  const Tuple2(this.item1, this.item2);
+
+  /// Create a new tuple value with the specified list [items].
+  factory Tuple2.fromList(List items) {
+    if (items.length != 2) {
+      throw ArgumentError('items must have length 2');
+    }
+
+    return Tuple2<T1, T2>(items[0] as T1, items[1] as T2);
+  }
+
+  /// Returns the first item of the tuple
+  final T1 item1;
+
+  /// Returns the second item of the tuple
+  final T2 item2;
+
+  /// Returns a tuple with the first item set to the specified value.
+  Tuple2<T1, T2> withItem1(T1 v) => Tuple2<T1, T2>(v, item2);
+
+  /// Returns a tuple with the second item set to the specified value.
+  Tuple2<T1, T2> withItem2(T2 v) => Tuple2<T1, T2>(item1, v);
+
+  /// Creates a [List] containing the items of this [Tuple2].
+  ///
+  /// The elements are in item order. The list is variable-length
+  /// if [growable] is true.
+  List toList({bool growable = false}) =>
+      List.from([item1, item2], growable: growable);
+
+  @override
+  String toString() => '[$item1, $item2]';
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is Tuple2 &&
+          runtimeType == other.runtimeType &&
+          item1 == other.item1 &&
+          item2 == other.item2;
+
+  @override
+  int get hashCode => item1.hashCode ^ item2.hashCode;
+}