Don't cache hashCode because items in collections might be mutable an…

…d allowed to change
passsy · Aug 15, 2021 · b727893 · b727893
1 parent f38b76e
commit b727893
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Showing 8 changed files with 38 additions and 9 deletions.
diff --git a/lib/src/collection/impl/list.dart b/lib/src/collection/impl/list.dart
@@ -10,7 +10,6 @@ class DartList<T> extends Object implements KtList<T> {
         super();
 
   final List<T> _list;
-  int? _hashCode;
 
   @override
   Iterable<T> get iter => _list;
@@ -76,7 +75,7 @@ class DartList<T> extends Object implements KtList<T> {
   }
 
   @override
-  int get hashCode => _hashCode ??= 1 + hashObjects(_list);
+  int get hashCode => 1 + hashObjects(_list);
 
   @override
   bool operator ==(dynamic other) {

diff --git a/lib/src/collection/impl/map.dart b/lib/src/collection/impl/map.dart
@@ -9,7 +9,6 @@ class DartMap<K, V> extends Object implements KtMap<K, V> {
         super();
 
   final Map<K, V> _map;
-  int? _hashCode;
 
   @override
   Iterable<KtMapEntry<K, V>> get iter =>
@@ -63,7 +62,7 @@ class DartMap<K, V> extends Object implements KtMap<K, V> {
 
   @override
   int get hashCode {
-    return _hashCode ??= hashObjects(_map.keys
+    return hashObjects(_map.keys
         .map((key) => hash2(key.hashCode, _map[key].hashCode))
         .toList(growable: false)
       ..sort());

diff --git a/lib/src/collection/impl/set.dart b/lib/src/collection/impl/set.dart
@@ -8,7 +8,6 @@ class DartSet<T> extends Object implements KtSet<T> {
         super();
 
   final Set<T> _set;
-  int? _hashCode;
 
   @override
   Iterable<T> get iter => _set;
@@ -41,7 +40,7 @@ class DartSet<T> extends Object implements KtSet<T> {
   int get size => _set.length;
 
   @override
-  int get hashCode => _hashCode ??=
+  int get hashCode =>
       hashObjects(_set.map((e) => e.hashCode).toList(growable: false)..sort());
 
   @override

diff --git a/lib/src/collection/kt_list.dart b/lib/src/collection/kt_list.dart
@@ -428,7 +428,6 @@ class _CastKtList<Source, T> implements KtList<T> {
   _CastKtList(KtList<Source> list) : _list = list;
 
   final KtList<Source> _list;
-  int? _hashCode;
 
   @override
   Iterable<T> get iter => _list.asList().cast();
@@ -496,7 +495,7 @@ class _CastKtList<Source, T> implements KtList<T> {
   }
 
   @override
-  int get hashCode => _hashCode ??= 1 + hashObjects(_list.asList());
+  int get hashCode => 1 + hashObjects(_list.asList());
 
   @override
   bool operator ==(dynamic other) {

diff --git a/test/collection/list_empty_test.dart b/test/collection/list_empty_test.dart
@@ -20,7 +20,7 @@ void main() {
     group("KtList.of", () {
       testEmptyList(<T>() => KtList<T>.of(), mutable: false);
     });
-    group("KtList.of", () {
+    group("KtList.from", () {
       testEmptyList(<T>() => KtList<T>.from(), mutable: false);
     });
     group("mutableListOf", () {

diff --git a/test/collection/list_test.dart b/test/collection/list_test.dart
@@ -191,6 +191,17 @@ void testList(
       expect(list0, isNot(equals(list2)));
       expect(list0.hashCode, isNot(equals(list2.hashCode)));
     });
+
+    test("hashcode changes when mutable value change", () {
+      final list = listOf(mutableListOf('a', 'b'), mutableListOf('c'));
+      final hash1 = list.hashCode;
+
+      // mutate content in list, not the list itself
+      list[1].add('d');
+
+      final hash2 = list.hashCode;
+      expect(hash2, isNot(hash1));
+    });
   });
 
   group("reduceRight", () {

diff --git a/test/collection/map_test.dart b/test/collection/map_test.dart
@@ -159,4 +159,15 @@ void testMap(KtMap<K, V> Function<K, V>(Map<K, V> map) mapFrom,
       expect(keys, listOf(1, 2));
     });
   });
+
+  test("hashcode changes when mutable value change", () {
+    final map = mapFrom({1: mutableListOf('a', 'b')});
+    final hash1 = map.hashCode;
+
+    // mutate content in map, not the map itself
+    map[1]!.add('d');
+
+    final hash2 = map.hashCode;
+    expect(hash2, isNot(hash1));
+  });
 }
diff --git a/test/collection/set_test.dart b/test/collection/set_test.dart
@@ -226,5 +226,16 @@ void testSet(
           catchException<UnsupportedError>(() => ktSet.asSet().add("asdf"));
       expect(e.message, contains("unmodifiable"));
     });
+
+    test("hashcode changes when mutable value change", () {
+      final set = setOf(mutableListOf('a', 'b'));
+      final hash1 = set.hashCode;
+
+      // mutate content in set, not the set itself
+      set.first().add('d');
+
+      final hash2 = set.hashCode;
+      expect(hash2, isNot(hash1));
+    });
   }
 }