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@sunderee
Created November 18, 2023 12:15
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Miniature "equatable", good enough for majority of use cases
import 'package:collection/collection.dart';
import 'package:meta/meta.dart';
const DeepCollectionEquality _equality = DeepCollectionEquality();
@immutable
abstract class Equatable {
const Equatable();
List<Object?> get props;
@override
bool operator ==(Object other) =>
identical(this, other) ||
other is Equatable &&
runtimeType == other.runtimeType &&
_equals(props, other.props);
@override
int get hashCode => runtimeType.hashCode ^ _finish(props.fold(0, _combine));
@override
String toString() =>
'$runtimeType(${props.map((prop) => prop.toString()).join(', ')})';
}
bool _equals(List<Object?>? list1, List<Object?>? list2) {
if (identical(list1, list2)) {
return true;
}
if (list1 == null || list2 == null) {
return false;
}
final length = list1.length;
if (length != list2.length) {
return false;
}
for (var i = 0; i < length; i++) {
final unit1 = list1[i];
final unit2 = list2[i];
if (_isEquatable(unit1) && _isEquatable(unit2)) {
if (unit1 != unit2) {
return false;
}
} else if (unit1 is Iterable || unit1 is Map) {
if (!_equality.equals(unit1, unit2)) {
return false;
}
} else if (unit1?.runtimeType != unit2?.runtimeType) {
return false;
} else if (unit1 != unit2) {
return false;
}
}
return true;
}
bool _isEquatable(Object? object) {
return object is Equatable;
}
int _combine(int hash, Object? object) {
if (object is Map) {
object.keys
.sorted((Object? a, Object? b) => a.hashCode - b.hashCode)
.forEach((Object? key) {
hash = hash ^ _combine(hash, [key, (object! as Map)[key]]);
});
return hash;
}
if (object is Set) {
object = object.sorted((Object? a, Object? b) => a.hashCode - b.hashCode);
}
if (object is Iterable) {
for (final value in object) {
hash = hash ^ _combine(hash, value);
}
return hash ^ object.length;
}
hash = 0x1fffffff & (hash + object.hashCode);
hash = 0x1fffffff & (hash + ((0x0007ffff & hash) << 10));
return hash ^ (hash >> 6);
}
int _finish(int hash) {
hash = 0x1fffffff & (hash + ((0x03ffffff & hash) << 3));
hash = hash ^ (hash >> 11);
return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
}
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