feat: Added automatic generation of == and hashCode method with @StoreConfig annotation

Author: amondnet

mobx/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.3.0
+
+- Added automatic generation of `==` and `hashCode` method with `@StoreConfig` annotation
+
 ## 2.2.3
 
 - Avoid unnecessary observable notifications of `@observable` `Iterable` or `Map` fields of Stores by [@amondnet](https://github.com/amondnet)  in [#951](https://github.com/mobxjs/mobx.dart/pull/951)

mobx/lib/src/api/annotations.dart

@@ -2,9 +2,10 @@
 /// Currently the only configuration used is boolean to indicate generation of toString method (true), or not (false)
 
 class StoreConfig {
-  const StoreConfig({this.hasToString = true});
+  const StoreConfig({this.hasToString = true, this.hasEqualsAndHashCode = true});
 
   final bool hasToString;
+  final bool hasEqualsAndHashCode;
 }
 
 /// Internal class only used for code-generation with `mobx_codegen`.

mobx/lib/src/api/store.dart

@@ -1,4 +1,5 @@
 import 'package:mobx/mobx.dart';
+import 'package:mobx/src/utils.dart';
 
 /// The `Store` mixin is primarily meant for code-generation and used as part of the
 /// `mobx_codegen` package.
@@ -9,4 +10,18 @@ import 'package:mobx/mobx.dart';
 mixin Store {
   /// Override this method to use a custom context.
   ReactiveContext get context => mainContext;
+
+  List<Object?> props = [];
+
+  @override
+  bool operator ==(Object other) {
+    return identical(this, other) ||
+        other is Store &&
+            runtimeType == other.runtimeType &&
+            equatable(props, other.props);
+  }
+
+  @override
+  int get hashCode => runtimeType.hashCode ^ mapPropsToHashCode(props);
+
 }

mobx/lib/src/utils.dart

@@ -1,6 +1,6 @@
 import 'dart:async';
 
-import 'package:collection/collection.dart' show DeepCollectionEquality;
+import 'package:collection/collection.dart' show DeepCollectionEquality, IterableExtension;
 
 const Duration ms = Duration(milliseconds: 1);
 
@@ -38,3 +38,40 @@ bool equatable<T>(T a, T b) {
 }
 
 const DeepCollectionEquality _equality = DeepCollectionEquality();
+
+/// Returns a `hashCode` for [props].
+int mapPropsToHashCode(Iterable<Object?>? props) {
+  return _finish(props == null ? 0 : props.fold(0, _combine));
+}
+
+/// Jenkins Hash Functions
+/// https://en.wikipedia.org/wiki/Jenkins_hash_function
+int _combine(int hash, Object? object) {
+  if (object is Map) {
+    object.keys
+        .sorted((Object? a, Object? b) => a.hashCode - b.hashCode)
+        .forEach((Object? key) {
+      hash = hash ^ _combine(hash, [key, (object! as Map)[key]]);
+    });
+    return hash;
+  }
+  if (object is Set) {
+    object = object.sorted((Object? a, Object? b) => a.hashCode - b.hashCode);
+  }
+  if (object is Iterable) {
+    for (final value in object) {
+      hash = hash ^ _combine(hash, value);
+    }
+    return hash ^ object.length;
+  }
+
+  hash = 0x1fffffff & (hash + object.hashCode);
+  hash = 0x1fffffff & (hash + ((0x0007ffff & hash) << 10));
+  return hash ^ (hash >> 6);
+}
+
+int _finish(int hash) {
+  hash = 0x1fffffff & (hash + ((0x03ffffff & hash) << 3));
+  hash = hash ^ (hash >> 11);
+  return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
+}

mobx/lib/version.dart

@@ -1,4 +1,4 @@
 // Generated via set_version.dart. !!!DO NOT MODIFY BY HAND!!!
 
 /// The current version as per `pubspec.yaml`.
-const version = '2.2.3';
+const version = '2.3.0';

mobx/pubspec.yaml

@@ -1,5 +1,5 @@
 name: mobx
-version: 2.2.3
+version: 2.3.0
 description: "MobX is a library for reactively managing the state of your applications. Use the power of observables, actions, and reactions to supercharge your Dart and Flutter apps."
 
 homepage: https://github.com/mobxjs/mobx.dart

mobx_codegen/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.5.0
+
+- Added automatic generation of `==` and `hashCode` method with `@StoreConfig` annotation
+
 ## 2.4.0
 
 - Require `analyzer: ^5.12.0`

mobx_codegen/lib/src/store_class_visitor.dart

@@ -73,6 +73,7 @@ class StoreClassVisitor extends SimpleElementVisitor {
     }
     // if the class is annotated to generate toString() method we add the information to the _storeTemplate
     _storeTemplate.generateToString = hasGeneratedToString(options, element);
+    _storeTemplate.generateEquals = hasGeneratedEquals(options, element);
   }
 
   @override
@@ -283,6 +284,22 @@ bool hasGeneratedToString(BuilderOptions options, ClassElement? classElement) {
   return true;
 }
 
+bool hasGeneratedEquals(BuilderOptions options, ClassElement? classElement) {
+  const fieldKey = 'hasEqualsAndHashCode';
+
+  if (classElement != null && isStoreConfigAnnotatedStoreClass(classElement)) {
+    final annotation =
+    _toStringAnnotationChecker.firstAnnotationOfExact(classElement);
+    return annotation?.getField(fieldKey)?.toBoolValue() ?? false;
+  }
+
+  if (options.config.containsKey(fieldKey)) {
+    return options.config[fieldKey]! as bool;
+  }
+
+  return true;
+}
+
 bool _any(List<bool> list) => list.any(_identity);
 
 T _identity<T>(T value) => value;

mobx_codegen/lib/src/template/store.dart

@@ -34,8 +34,10 @@ abstract class StoreTemplate {
   final Rows<ObservableFutureTemplate> observableFutures = Rows();
   final Rows<ObservableStreamTemplate> observableStreams = Rows();
   final List<String> toStringList = [];
+  final List<String> props = [];
 
   bool generateToString = false;
+  bool generateEquals = true;
   String? _actionControllerName;
   String get actionControllerName =>
       _actionControllerName ??= '_\$${parentTypeName}ActionController';
@@ -72,6 +74,24 @@ ${allStrings.join(',\n')}
   ''';
   }
 
+  String get propsMethod {
+    if (!generateEquals) {
+      return '';
+    }
+
+    final allObservables = observables.templates
+        .map((current) => 'super.${current.name}');
+
+    final allProps = props..addAll(allObservables);
+
+    // The indents have been kept to ensure each field comes on a separate line without any tabs/spaces
+    return '''
+  @override
+  List<Object?> get props => [${allProps.join(', ')}];
+  ''';
+  }
+
+
   String get storeBody => '''
   $computeds
 
@@ -88,5 +108,7 @@ ${allStrings.join(',\n')}
   $actions
 
   $toStringMethod
+  
+  $propsMethod
   ''';
 }

mobx_codegen/lib/version.dart

@@ -1,4 +1,4 @@
 // Generated via set_version.dart. !!!DO NOT MODIFY BY HAND!!!
 
 /// The current version as per `pubspec.yaml`.
-const version = '2.4.0';
+const version = '2.5.0';