perf: improve equality comparison performance

lib/src/equatable.dart

@@ -1,3 +1,4 @@
+import 'package:equatable/src/equatable_comparison_utils.dart';
 import 'package:equatable/src/equatable_config.dart';
 import 'package:equatable/src/equatable_utils.dart';
 import 'package:meta/meta.dart';

lib/src/equatable_comparison_utils.dart

@@ -0,0 +1,84 @@
+import 'package:equatable/src/equatable.dart';
+import 'package:equatable/src/equatable_mixin.dart';
+
+/// Determines whether [list1] and [list2] are equal.
+// This method is optimized for comparing properties
+// from primitive types like int, double, String, bool.
+// Using the _iterableEquals method instead of this code
+// can degrade performance by ~ 20%.
+bool equals(List<Object?> list1, List<Object?> list2) {
+  if (identical(list1, list2)) return true;
+  final length = list1.length;
+  if (length != list2.length) return false;
+
+  for (var i = 0; i < length; i++) {
+    final unit1 = list1[i];
+    final unit2 = list2[i];
+
+    if (_isEquatable(unit1) && _isEquatable(unit2)) {
+      if (unit1 != unit2) return false;
+    } else if (unit1 is Iterable && unit2 is Iterable) {
+      return _iterableEquals(unit1, unit2);
+    } else if (unit1 is Set && unit2 is Set) {
+      return _setEquals(unit1, unit2);
+    } else if (unit1 is Map && unit2 is Map) {
+      return _mapEquals(unit1, unit2);
+    } else if (unit1?.runtimeType != unit2?.runtimeType) {
+      return false;
+    } else if (unit1 != unit2) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool _objectsEquals(Object? object1, Object? object2) {
+  if (identical(object1, object2)) {
+    return true;
+  } else if (_isEquatable(object1) && _isEquatable(object2)) {
+    if (object1 != object2) return false;
+  } else if (object1 is List && object2 is List) {
+    return _iterableEquals(object1, object2);
+  } else if (object1 is Set && object2 is Set) {
+    return _setEquals(object1, object2);
+  } else if (object1 is Map && object2 is Map) {
+    return _mapEquals(object1, object2);
+  } else if (object1?.runtimeType != object2?.runtimeType) {
+    return false;
+  } else if (object1 != object2) {
+    return false;
+  }
+  return true;
+}
+
+bool _isEquatable(Object? object) {
+  return object is Equatable || object is EquatableMixin;
+}
+
+bool _setEquals(Set<Object?> a, Set<Object?> b) {
+  if (a.length != b.length) return false;
+  if (identical(a, b)) return true;
+  for (final element in a) {
+    if (!b.contains(element)) return false;
+  }
+  return true;
+}
+
+bool _iterableEquals(Iterable<Object?> a, Iterable<Object?> b) {
+  if (identical(a, b)) return true;
+  final aLength = a.length;
+  if (aLength != b.length) return false;
+  for (var i = 0; i < aLength; i++) {
+    if (!_objectsEquals(a.elementAt(i), b.elementAt(i))) return false;
+  }
+  return true;
+}
+
+bool _mapEquals(Map<Object?, Object?> a, Map<Object?, Object?> b) {
+  if (a.length != b.length) return false;
+  if (identical(a, b)) return true;
+  for (final key in a.keys) {
+    if (!_objectsEquals(a[key], b[key])) return false;
+  }
+  return true;
+}

lib/src/equatable_mixin.dart

@@ -1,4 +1,5 @@
 import 'package:equatable/src/equatable.dart';
+import 'package:equatable/src/equatable_comparison_utils.dart';
 import 'package:equatable/src/equatable_config.dart';
 import 'package:equatable/src/equatable_utils.dart';
 import 'package:meta/meta.dart';

lib/src/equatable_utils.dart

@@ -1,41 +1,10 @@
 import 'package:collection/collection.dart';
-import 'package:equatable/equatable.dart';
 
 /// Returns a `hashCode` for [props].
 int mapPropsToHashCode(Iterable<Object?>? props) {
   return _finish(props == null ? 0 : props.fold(0, _combine));
 }
 
-const DeepCollectionEquality _equality = DeepCollectionEquality();
-
-/// Determines whether [list1] and [list2] are equal.
-bool equals(List<Object?>? list1, List<Object?>? list2) {
-  if (identical(list1, list2)) return true;
-  if (list1 == null || list2 == null) return false;
-  final length = list1.length;
-  if (length != list2.length) return false;
-
-  for (var i = 0; i < length; i++) {
-    final unit1 = list1[i];
-    final unit2 = list2[i];
-
-    if (_isEquatable(unit1) && _isEquatable(unit2)) {
-      if (unit1 != unit2) return false;
-    } else if (unit1 is Iterable || unit1 is Map) {
-      if (!_equality.equals(unit1, unit2)) return false;
-    } else if (unit1?.runtimeType != unit2?.runtimeType) {
-      return false;
-    } else if (unit1 != unit2) {
-      return false;
-    }
-  }
-  return true;
-}
-
-bool _isEquatable(Object? object) {
-  return object is Equatable || object is EquatableMixin;
-}
-
 /// Jenkins Hash Functions
 /// https://en.wikipedia.org/wiki/Jenkins_hash_function
 int _combine(int hash, Object? object) {