[objective_c] Collections support for NS[Mutable]Dictionary and NS[Mutable]Set (#2234)

Author: liamappelbe

pkgs/objective_c/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 - Use ffigen 18.2.0
 - `NSArray` is now a Dart `Iterable` and `NSMutableArray` is now a Dart `List`.
+- `NSDictionary` and `NSMutableDictionary` are now Dart `Map`s.
+- `NSSet` and `NSMutableSet` are now Dart `Set`s.
 - Add `.toNSNumber()` extension method to `int`, `double`, and `num`.
 
 ## 7.1.0

pkgs/objective_c/lib/src/objective_c_bindings_generated.dart

@@ -2022,7 +2022,39 @@ class NSDate extends NSObject implements NSCopying, NSSecureCoding {
 
 /// NSDictionary
 class NSDictionary extends NSObject
+    with MapBase<NSCopying, objc.ObjCObjectBase>
     implements NSCopying, NSMutableCopying, NSSecureCoding, NSFastEnumeration {
+  /// Creates a [NSDictionary] from [other].
+  static NSDictionary of(Map<NSCopying, objc.ObjCObjectBase> other) =>
+      NSMutableDictionary.of(other);
+
+  @override
+  int get length => count;
+
+  @override
+  objc.ObjCObjectBase? operator [](Object? key) =>
+      key is NSCopying ? objectForKey_(key) : null;
+
+  @override
+  Iterable<NSCopying> get keys => _NSDictionaryKeyIterable(this);
+
+  @override
+  Iterable<objc.ObjCObjectBase> get values => _NSDictionaryValueIterable(this);
+
+  @override
+  bool containsKey(Object? key) => this[key] != null;
+
+  @override
+  void operator []=(NSCopying key, objc.ObjCObjectBase value) =>
+      throw UnsupportedError("Cannot modify NSDictionary");
+
+  @override
+  void clear() => throw UnsupportedError("Cannot modify NSDictionary");
+
+  @override
+  objc.ObjCObjectBase? remove(Object? key) =>
+      throw UnsupportedError("Cannot modify NSDictionary");
+
   NSDictionary._(ffi.Pointer<objc.ObjCObject> pointer,
       {bool retain = false, bool release = false})
       : super.castFromPointer(pointer, retain: retain, release: release);
@@ -2228,7 +2260,20 @@ enum NSEnumerationOptions {
 }
 
 /// NSEnumerator
-class NSEnumerator extends NSObject implements NSFastEnumeration {
+class NSEnumerator extends NSObject
+    implements NSFastEnumeration, Iterator<objc.ObjCObjectBase> {
+  objc.ObjCObjectBase? _current;
+
+  @override
+  objc.ObjCObjectBase get current => _current!;
+
+  @override
+  @pragma('vm:prefer-inline')
+  bool moveNext() {
+    _current = nextObject();
+    return _current != null;
+  }
+
   NSEnumerator._(ffi.Pointer<objc.ObjCObject> pointer,
       {bool retain = false, bool release = false})
       : super.castFromPointer(pointer, retain: retain, release: release);
@@ -4694,7 +4739,7 @@ class NSMethodSignature extends NSObject {
 }
 
 /// NSMutableArray
-class NSMutableArray extends NSArray with ListMixin<objc.ObjCObjectBase> {
+class NSMutableArray extends NSArray with ListBase<objc.ObjCObjectBase> {
   /// Creates a [NSMutableArray] of the given length with [fill] at each
   /// position.
   ///
@@ -4716,18 +4761,19 @@ class NSMutableArray extends NSArray with ListMixin<objc.ObjCObjectBase> {
     for (; len > newLength; --len) removeLastObject();
   }
 
+  @override
+  Iterator<objc.ObjCObjectBase> get iterator => _NSArrayIterator(this);
+
+  @override
+  objc.ObjCObjectBase operator [](int index) => objectAtIndex_(index);
+
   @override
   void operator []=(int index, objc.ObjCObjectBase value) =>
       replaceObjectAtIndex_withObject_(index, value);
 
   @override
   void add(objc.ObjCObjectBase value) => addObject_(value);
 
-  @override
-  void addAll(Iterable<objc.ObjCObjectBase> iterable) {
-    for (final value in iterable) add(value);
-  }
-
   NSMutableArray._(ffi.Pointer<objc.ObjCObject> pointer,
       {bool retain = false, bool release = false})
       : super.castFromPointer(pointer, retain: retain, release: release);
@@ -5339,6 +5385,25 @@ class NSMutableData extends NSData {
 
 /// NSMutableDictionary
 class NSMutableDictionary extends NSDictionary {
+  /// Creates a [NSMutableDictionary] from [other].
+  static NSDictionary of(Map<NSCopying, objc.ObjCObjectBase> other) =>
+      NSMutableDictionary.dictionaryWithCapacity_(other.length)..addAll(other);
+
+  @override
+  void clear() => removeAllObjects();
+
+  @override
+  objc.ObjCObjectBase? remove(Object? key) {
+    if (key is! NSCopying) return null;
+    final old = this[key];
+    removeObjectForKey_(key);
+    return old;
+  }
+
+  @override
+  void operator []=(NSCopying key, objc.ObjCObjectBase value) =>
+      setObject_forKey_(value, NSCopying.castFrom(key));
+
   NSMutableDictionary._(ffi.Pointer<objc.ObjCObject> pointer,
       {bool retain = false, bool release = false})
       : super.castFromPointer(pointer, retain: retain, release: release);
@@ -6083,6 +6148,28 @@ class NSMutableOrderedSet extends NSOrderedSet {
 
 /// NSMutableSet
 class NSMutableSet extends NSSet {
+  /// Creates a [NSMutableSet] from [elements].
+  static NSMutableSet of(Iterable<objc.ObjCObjectBase> elements) =>
+      setWithCapacity_(elements.length)..addAll(elements);
+
+  @override
+  bool add(objc.ObjCObjectBase value) {
+    final alreadyContains = contains(value);
+    addObject_(value);
+    return !alreadyContains;
+  }
+
+  @override
+  bool remove(Object? value) {
+    if (value is! objc.ObjCObjectBase) return false;
+    final alreadyContains = contains(value);
+    removeObject_(value);
+    return alreadyContains;
+  }
+
+  @override
+  void clear() => removeAllObjects();
+
   NSMutableSet._(ffi.Pointer<objc.ObjCObject> pointer,
       {bool retain = false, bool release = false})
       : super.castFromPointer(pointer, retain: retain, release: release);
@@ -9379,7 +9466,39 @@ interface class NSSecureCoding extends objc.ObjCProtocolBase
 
 /// NSSet
 class NSSet extends NSObject
+    with SetBase<objc.ObjCObjectBase>
     implements NSCopying, NSMutableCopying, NSSecureCoding, NSFastEnumeration {
+  /// Creates a [NSSet] from [elements].
+  static NSSet of(Iterable<objc.ObjCObjectBase> elements) =>
+      NSMutableSet.of(elements);
+
+  @override
+  int get length => count;
+
+  @override
+  bool contains(Object? element) =>
+      element is objc.ObjCObjectBase ? containsObject_(element) : false;
+
+  @override
+  objc.ObjCObjectBase? lookup(Object? element) =>
+      element is objc.ObjCObjectBase ? member_(element) : null;
+
+  @override
+  Iterator<objc.ObjCObjectBase> get iterator => objectEnumerator();
+
+  @override
+  Set<objc.ObjCObjectBase> toSet() => {...this};
+
+  @override
+  bool add(objc.ObjCObjectBase value) =>
+      throw UnsupportedError("Cannot modify NSSet");
+
+  @override
+  bool remove(Object? value) => throw UnsupportedError("Cannot modify NSSet");
+
+  @override
+  void clear() => throw UnsupportedError("Cannot modify NSSet");
+
   NSSet._(ffi.Pointer<objc.ObjCObject> pointer,
       {bool retain = false, bool release = false})
       : super.castFromPointer(pointer, retain: retain, release: release);
@@ -18498,3 +18617,43 @@ class _NSArrayIterator implements Iterator<objc.ObjCObjectBase> {
     return true;
   }
 }
+
+class _NSDictionaryKeyIterable with Iterable<NSCopying> {
+  NSDictionary _dictionary;
+
+  _NSDictionaryKeyIterable(this._dictionary);
+
+  @override
+  int get length => _dictionary.length;
+
+  @override
+  Iterator<NSCopying> get iterator =>
+      _NSDictionaryKeyIterator(_dictionary.keyEnumerator());
+
+  @override
+  bool contains(Object? key) => _dictionary.containsKey(key);
+}
+
+class _NSDictionaryValueIterable with Iterable<objc.ObjCObjectBase> {
+  NSDictionary _dictionary;
+
+  _NSDictionaryValueIterable(this._dictionary);
+
+  @override
+  int get length => _dictionary.length;
+
+  @override
+  Iterator<objc.ObjCObjectBase> get iterator => _dictionary.objectEnumerator();
+}
+
+class _NSDictionaryKeyIterator implements Iterator<NSCopying> {
+  final Iterator<objc.ObjCObjectBase> _iterator;
+  _NSDictionaryKeyIterator(this._iterator);
+
+  @override
+  NSCopying get current => NSCopying.castFrom(_iterator.current);
+
+  @override
+  @pragma('vm:prefer-inline')
+  bool moveNext() => _iterator.moveNext();
+}

pkgs/objective_c/test/nsdictionary_test.dart

@@ -0,0 +1,113 @@
+// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Objective C support is only available on mac.
+@TestOn('mac-os')
+library;
+
+import 'dart:ffi';
+
+import 'package:objective_c/objective_c.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('NSDictionary', () {
+    setUpAll(() {
+      // TODO(https://github.com/dart-lang/native/issues/1068): Remove this.
+      DynamicLibrary.open('test/objective_c.dylib');
+    });
+
+    test('of', () {
+      final obj1 = 'obj1'.toNSString();
+      final obj2 = 'obj2'.toNSString();
+      final obj3 = 'obj3'.toNSString();
+      final obj4 = 'obj4'.toNSString();
+      final obj5 = 'obj5'.toNSString();
+      final obj6 = 'obj6'.toNSString();
+
+      final dict = NSDictionary.of({
+        obj1: obj2,
+        obj3: obj4,
+        obj5: obj6,
+      });
+
+      expect(dict.length, 3);
+      expect(dict[obj1], obj2);
+      expect(dict[obj3], obj4);
+      expect(dict[obj5], obj6);
+
+      // Keys are copied, so compare the string values.
+      final actualKeys = <String>[];
+      for (final key in dict.keys) {
+        actualKeys.add(NSString.castFrom(key).toDartString());
+      }
+      expect(actualKeys, unorderedEquals(['obj1', 'obj3', 'obj5']));
+
+      // Values are stored by reference, so we can compare the actual objects.
+      final actualValues = <ObjCObjectBase>[];
+      for (final value in dict.values) {
+        actualValues.add(value);
+      }
+      expect(actualValues, unorderedEquals([obj2, obj4, obj6]));
+    });
+
+    test('immutable', () {
+      final obj1 = 'obj1'.toNSString();
+      final obj2 = 'obj2'.toNSString();
+      final obj3 = 'obj3'.toNSString();
+      final obj4 = 'obj4'.toNSString();
+      final obj5 = 'obj5'.toNSString();
+      final obj6 = 'obj6'.toNSString();
+
+      // NSDictionary.of actually returns a NSMutableDictionary, so our
+      // immutability tests wouldn't actually work. So convert it to a real
+      // NSDictionary using an ObjC constructor.
+      final dict = NSDictionary.dictionaryWithDictionary_(NSDictionary.of({
+        obj1: obj2,
+        obj3: obj4,
+        obj5: obj6,
+      }));
+
+      expect(() => dict[obj3] = obj1, throwsUnsupportedError);
+      expect(dict.clear, throwsUnsupportedError);
+      expect(() => dict.remove(obj1), throwsUnsupportedError);
+    });
+
+    test('MapBase mixin', () {
+      final obj1 = 'obj1'.toNSString();
+      final obj2 = 'obj2'.toNSString();
+      final obj3 = 'obj3'.toNSString();
+      final obj4 = 'obj4'.toNSString();
+      final obj5 = 'obj5'.toNSString();
+      final obj6 = 'obj6'.toNSString();
+
+      final dict = NSDictionary.of({
+        obj1: obj2,
+        obj3: obj4,
+        obj5: obj6,
+      });
+
+      expect(dict.isNotEmpty, isTrue);
+      expect(dict.containsKey(obj1), isTrue);
+      expect(dict.containsKey(obj4), isFalse);
+      expect(dict.containsValue(obj2), isTrue);
+      expect(dict.containsValue(obj3), isFalse);
+
+      expect(
+          dict.map((key, value) =>
+              MapEntry<ObjCObjectBase, ObjCObjectBase>(value, key)),
+          {
+            obj2: obj1,
+            obj4: obj3,
+            obj6: obj5,
+          });
+      expect(
+          dict.keys
+              .map((key) => NSString.castFrom(key).toDartString())
+              .toList(),
+          unorderedEquals(['obj1', 'obj3', 'obj5']));
+      expect(dict.values.toList(), unorderedEquals([obj2, obj4, obj6]));
+    });
+  });
+}