feat(core): Add a list constructor to TypedMap

packages/moxxmpp/lib/src/util/typed_map.dart

@@ -1,5 +1,15 @@
 /// A map, similar to Map, but always uses the type of the value as the key.
 class TypedMap<B> {
+  /// Create an empty typed map.
+  TypedMap();
+
+  /// Create a typed map from a list of values.
+  TypedMap.fromList(List<B> items) {
+    for (final item in items) {
+      _data[item.runtimeType] = item;
+    }
+  }
+
   /// The internal mapping of type -> data
   final Map<Object, B> _data = {};
 

packages/moxxmpp/test/type_map_test.dart

@@ -24,4 +24,16 @@ void main() {
     expect(map.get<TestType1>()?.i, 1);
     expect(map.get<TestType2>()?.j, false);
   });
+
+  test('Test storing data in the type map using a list', () {
+    // Set
+    final map = TypedMap<BaseType>.fromList([
+      const TestType1(1),
+      const TestType2(false),
+    ]);
+
+    // And access
+    expect(map.get<TestType1>()?.i, 1);
+    expect(map.get<TestType2>()?.j, false);
+  });
 }