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merged 4 commits into from
Apr 3, 2025
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[collection] explicitly make BoolList abstract interface #875

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80a7330
[collection] explicitly make BoolList abstract interface
kevmoo Apr 2, 2025
c0d8bf8
go with @sealed for BoolList for now
kevmoo Apr 2, 2025
a0c328b
fix comment
kevmoo Apr 3, 2025
57bc094
prefer inline
kevmoo Apr 3, 2025
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1 change: 1 addition & 0 deletions pkgs/collection/CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@

- Add `IterableMapEntryExtension` for working on `Map` as a list of pairs, using
`Map.entries`.
- Explicitly mark `BoolList` as `abstract interface`
- Address diagnostics from `strict_top_level_inference`.

## 1.19.1
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27 changes: 18 additions & 9 deletions pkgs/collection/lib/src/boollist.dart
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Expand Up @@ -5,12 +5,16 @@
import 'dart:collection' show ListMixin;
import 'dart:typed_data' show Uint32List;

import 'package:meta/meta.dart';

import 'unmodifiable_wrappers.dart' show NonGrowableListMixin;

/// A space-efficient list of boolean values.
///
/// Uses list of integers as internal storage to reduce memory usage.
abstract /*mixin*/ class BoolList with ListMixin<bool> {
@sealed
// TODO: replace `interface` with `final` in the next major release.
abstract interface class BoolList with ListMixin<bool> {
static const int _entryShift = 5;

static const int _bitsPerEntry = 32;
Expand Down Expand Up @@ -119,9 +123,7 @@ abstract /*mixin*/ class BoolList with ListMixin<bool> {
@override
bool operator [](int index) {
RangeError.checkValidIndex(index, this, 'index', _length);
return (_data[index >> _entryShift] &
(1 << (index & _entrySignBitIndex))) !=
0;
return _getBit(index);
}

@override
Expand Down Expand Up @@ -167,6 +169,7 @@ abstract /*mixin*/ class BoolList with ListMixin<bool> {
@override
Iterator<bool> get iterator => _BoolListIterator(this);

// Note: [index] is NOT checked for validity.
void _setBit(int index, bool value) {
if (value) {
_data[index >> _entryShift] |= 1 << (index & _entrySignBitIndex);
Expand All @@ -175,12 +178,19 @@ abstract /*mixin*/ class BoolList with ListMixin<bool> {
}
}

// Note: [index] is NOT checked for validity.
@pragma('dart2js:prefer-inline')
@pragma('vm:prefer-inline')
@pragma('wasm:prefer-inline')
bool _getBit(int index) =>
(_data[index >> _entryShift] & (1 << (index & _entrySignBitIndex))) != 0;

static int _lengthInWords(int bitLength) {
return (bitLength + (_bitsPerEntry - 1)) >> _entryShift;
}
}

class _GrowableBoolList extends BoolList {
final class _GrowableBoolList extends BoolList {
static const int _growthFactor = 2;

_GrowableBoolList._withCapacity(int length, int capacity)
Expand Down Expand Up @@ -228,7 +238,8 @@ class _GrowableBoolList extends BoolList {
}
}

class _NonGrowableBoolList extends BoolList with NonGrowableListMixin<bool> {
final class _NonGrowableBoolList extends BoolList
with NonGrowableListMixin<bool> {
_NonGrowableBoolList._withCapacity(int length, int capacity)
: super._(
Uint32List(BoolList._lengthInWords(capacity)),
Expand Down Expand Up @@ -262,9 +273,7 @@ class _BoolListIterator implements Iterator<bool> {

if (_pos < _boolList.length) {
var pos = _pos++;
_current = _boolList._data[pos >> BoolList._entryShift] &
(1 << (pos & BoolList._entrySignBitIndex)) !=
0;
_current = _boolList._getBit(pos);
return true;
}
_current = false;
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3 changes: 3 additions & 0 deletions pkgs/collection/pubspec.yaml
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Expand Up @@ -12,6 +12,9 @@ topics:
environment:
sdk: ^3.4.0

dependencies:
meta: ^1.16.0

dev_dependencies:
benchmark_harness: ^2.3.1
dart_flutter_team_lints: ^3.0.0
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