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Impl (#78218)

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Tong Mu 2021-03-16 09:38:04 -07:00 committed by GitHub
parent 4266d629c2
commit 7dca2e54a0
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1 changed files with 11 additions and 17 deletions
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28
packages/flutter/lib/src/widgets/shortcuts.dart
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@ -26,6 +26,7 @@ import 'inherited_notifier.dart';
/// ///
/// * [ShortcutManager], which uses [LogicalKeySet] (a [KeySet] subclass) to /// * [ShortcutManager], which uses [LogicalKeySet] (a [KeySet] subclass) to
/// define its key map. /// define its key map.
@immutable
class KeySet<T extends KeyboardKey> { class KeySet<T extends KeyboardKey> {
/// A constructor for making a [KeySet] of up to four keys. /// A constructor for making a [KeySet] of up to four keys.
/// ///
@ -81,7 +82,6 @@ class KeySet<T extends KeyboardKey> {
final HashSet<T> _keys; final HashSet<T> _keys;
@override @override
// ignore: avoid_equals_and_hash_code_on_mutable_classes, to remove in NNBD with a late final hashcode
bool operator ==(Object other) { bool operator ==(Object other) {
if (other.runtimeType != runtimeType) { if (other.runtimeType != runtimeType) {
return false; return false;
@ -90,25 +90,19 @@ class KeySet<T extends KeyboardKey> {
&& setEquals<T>(other._keys, _keys); && setEquals<T>(other._keys, _keys);
} }
// Arrays used to temporarily store hash codes for sorting.
static final List<int> _tempHashStore3 = <int>[0, 0, 0]; // used to sort exactly 3 keys
static final List<int> _tempHashStore4 = <int>[0, 0, 0, 0]; // used to sort exactly 4 keys
// Cached hash code value. Improves [hashCode] performance by 27%-900%, // Cached hash code value. Improves [hashCode] performance by 27%-900%,
// depending on key set size and read/write ratio. // depending on key set size and read/write ratio.
int? _hashCode;
@override @override
// ignore: avoid_equals_and_hash_code_on_mutable_classes, to remove in NNBD with a late final hashcode late final int hashCode = _computeHashCode(_keys);
int get hashCode {
// Return cached hash code if available.
if (_hashCode != null) {
return _hashCode!;
}
// Arrays used to temporarily store hash codes for sorting.
static final List<int> _tempHashStore3 = <int>[0, 0, 0]; // used to sort exactly 3 keys
static final List<int> _tempHashStore4 = <int>[0, 0, 0, 0]; // used to sort exactly 4 keys
static int _computeHashCode<T>(Set<T> keys) {
// Compute order-independent hash and cache it. // Compute order-independent hash and cache it.
final int length = _keys.length; final int length = keys.length;
final Iterator<T> iterator = _keys.iterator; final Iterator<T> iterator = keys.iterator;
// There's always at least one key. Just extract it. // There's always at least one key. Just extract it.
iterator.moveNext(); iterator.moveNext();
@ -116,14 +110,14 @@ class KeySet<T extends KeyboardKey> {
if (length == 1) { if (length == 1) {
// Don't do anything fancy if there's exactly one key. // Don't do anything fancy if there's exactly one key.
return _hashCode = h1; return h1;
} }
iterator.moveNext(); iterator.moveNext();
final int h2 = iterator.current.hashCode; final int h2 = iterator.current.hashCode;
if (length == 2) { if (length == 2) {
// No need to sort if there's two keys, just compare them. // No need to sort if there's two keys, just compare them.
return _hashCode = h1 < h2 return h1 < h2
? hashValues(h1, h2) ? hashValues(h1, h2)
: hashValues(h2, h1); : hashValues(h2, h1);
} }
@ -142,7 +136,7 @@ class KeySet<T extends KeyboardKey> {
sortedHashes[3] = iterator.current.hashCode; sortedHashes[3] = iterator.current.hashCode;
} }
sortedHashes.sort(); sortedHashes.sort();
return _hashCode = hashList(sortedHashes); return hashList(sortedHashes);
} }
} }