firka/flutter
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Fix KeySet<T> (and LogicalKeySet, PhysicalKeySet) hashCode calculation (#38936)

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This fixes the hashCode calculation for KeySet<T> so that it doesn't depend on the insertion order of the keys in the set.

The fix involves switching from Set<T> to HashSet<T> internally, so that the iteration order is stable around the hash values of the inserted keys, and not the insertion order. This matters when hashList is called in KeySet<T>.hashCode to build the hash value of the contents of the internal set.

Fixes #38919
This commit is contained in:
Greg Spencer 2019-08-23 07:51:35 -07:00 committed by GitHub
parent 01a5d112d5
commit 055c548902
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 28 additions and 3 deletions
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11
packages/flutter/lib/src/widgets/shortcuts.dart
View File

@ -2,6 +2,8 @@
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:collection';
import 'package:collection/collection.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
@ -39,7 +41,7 @@ class KeySet<T extends KeyboardKey> extends Diagnosticable {
T key3,
T key4,
]) : assert(key1 != null),
_keys = <T>{key1} {
_keys = HashSet<T>()..add(key1) {
int count = 1;
if (key2 != null) {
_keys.add(key2);
@ -74,11 +76,14 @@ class KeySet<T extends KeyboardKey> extends Diagnosticable {
: assert(keys != null),
assert(keys.isNotEmpty),
assert(!keys.contains(null)),
_keys = keys;
_keys = HashSet<T>.from(keys);
/// Returns an unmodifiable view of the [KeyboardKey]s in this [KeySet].
Set<T> get keys => UnmodifiableSetView<T>(_keys);
final Set<T> _keys;
// This needs to be a hash set to be sure that the hashCode accessor returns
// consistent results. LinkedHashSet (the default Set implementation) depends
// upon insertion order, and HashSet does not.
final HashSet<T> _keys;
@override
bool operator ==(Object other) {

20
packages/flutter/test/widgets/shortcuts_test.dart
View File

@ -167,8 +167,26 @@ void main() {
final LogicalKeySet set2 = LogicalKeySet(
LogicalKeyboardKey.keyA,
LogicalKeyboardKey.keyB,
LogicalKeyboardKey.keyC,
LogicalKeyboardKey.keyD,
);
final LogicalKeySet set3 = LogicalKeySet(
LogicalKeyboardKey.keyD,
LogicalKeyboardKey.keyC,
LogicalKeyboardKey.keyB,
LogicalKeyboardKey.keyA,
);
final LogicalKeySet set4 = LogicalKeySet.fromSet(<LogicalKeyboardKey>{
LogicalKeyboardKey.keyD,
LogicalKeyboardKey.keyC,
LogicalKeyboardKey.keyB,
LogicalKeyboardKey.keyA,}
);
final Map<LogicalKeySet, String> map = <LogicalKeySet, String>{set1: 'one'};
expect(set2 == set3, isTrue);
expect(set2 == set4, isTrue);
expect(set2.hashCode == set3.hashCode, isTrue);
expect(set2.hashCode == set4.hashCode, isTrue);
expect(map.containsKey(set1), isTrue);
expect(map.containsKey(LogicalKeySet(LogicalKeyboardKey.keyA)), isTrue);
expect(
@ -176,6 +194,8 @@ void main() {
equals(LogicalKeySet.fromSet(<LogicalKeyboardKey>{
LogicalKeyboardKey.keyA,
LogicalKeyboardKey.keyB,
LogicalKeyboardKey.keyC,
LogicalKeyboardKey.keyD,
})));
});
test('$KeySet diagnostics work.', () {