29 lines
711 B
Dart
29 lines
711 B
Dart
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import 'dart:async';
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class CancelledException implements Exception {
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final String? reason;
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const CancelledException([this.reason]);
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@override
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String toString() =>
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reason == null ? 'CancelledException' : 'CancelledException: $reason';
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}
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class CancellationToken {
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final Completer<void> _completer = Completer<void>();
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String? _reason;
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bool get isCancelled => _completer.isCompleted;
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String? get reason => _reason;
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Future<void> get whenCancelled => _completer.future;
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void cancel([String? reason]) {
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if (_completer.isCompleted) return;
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_reason = reason;
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_completer.complete();
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}
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void throwIfCancelled() {
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if (isCancelled) throw CancelledException(_reason);
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}
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}
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