Avoid unnecessary observable notifications of Iterable or Map fields

mobxjs · Nov 2, 2023 · 39e5f28 · 39e5f28
1 parent 74dba7d
commit 39e5f28
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Showing 3 changed files with 22 additions and 19 deletions.
diff --git a/mobx/lib/src/core/atom_extensions.dart b/mobx/lib/src/core/atom_extensions.dart
@@ -1,6 +1,7 @@
-import 'package:collection/collection.dart';
 import 'package:mobx/mobx.dart';
 
+import '../utils.dart';
+
 extension AtomSpyReporter on Atom {
   void reportRead() {
     context.enforceReadPolicy(this);
@@ -10,7 +11,7 @@ extension AtomSpyReporter on Atom {
   void reportWrite<T>(T newValue, T oldValue, void Function() setNewValue,
       {EqualityComparer<T>? equals}) {
     final areEqual = equals == null
-        ? _equals(oldValue, newValue)
+        ? equatable(oldValue, newValue)
         : equals(oldValue, newValue);
 
     // Avoid unnecessary observable notifications of @observable fields of Stores
@@ -33,19 +34,3 @@ extension AtomSpyReporter on Atom {
     context.spyReport(EndedSpyEvent(type: 'observable', name: name));
   }
 }
-
-/// Determines whether [a] and [b] are equal.
-bool _equals<T>(T a, T b) {
-  if (identical(a, b)) return true;
-  if (a is Iterable || a is Map) {
-    if (!_equality.equals(a, b)) return false;
-  } else if (a.runtimeType != b.runtimeType) {
-    return false;
-  } else if (a != b) {
-    return false;
-  }
-
-  return true;
-}
-
-const DeepCollectionEquality _equality = DeepCollectionEquality();
diff --git a/mobx/lib/src/core/observable.dart b/mobx/lib/src/core/observable.dart
@@ -105,7 +105,7 @@ class Observable<T> extends Atom
     }
 
     final areEqual =
-        equals == null ? prepared == value : equals!(prepared, _value);
+        equals == null ? equatable(prepared, value) : equals!(prepared, _value);
 
     return (!areEqual) ? prepared : WillChangeNotification.unchanged;
   }

diff --git a/mobx/lib/src/utils.dart b/mobx/lib/src/utils.dart
@@ -1,5 +1,7 @@
 import 'dart:async';
 
+import 'package:collection/collection.dart' show DeepCollectionEquality;
+
 const Duration ms = Duration(milliseconds: 1);
 
 Timer Function(void Function()) createDelayedScheduler(int delayMs) =>
@@ -20,3 +22,19 @@ mixin DebugCreationStack {
     return result;
   }();
 }
+
+/// Determines whether [a] and [b] are equal.
+bool equatable<T>(T a, T b) {
+  if (identical(a, b)) return true;
+  if (a is Iterable || a is Map) {
+    if (!_equality.equals(a, b)) return false;
+  } else if (a.runtimeType != b.runtimeType) {
+    return false;
+  } else if (a != b) {
+    return false;
+  }
+
+  return true;
+}
+
+const DeepCollectionEquality _equality = DeepCollectionEquality();