using System.Threading;
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namespace Cysharp.Threading.Tasks.Linq
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{
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public static partial class UniTaskAsyncEnumerable
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{
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public static IUniTaskAsyncEnumerable<T> Never<T>()
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{
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return Cysharp.Threading.Tasks.Linq.Never<T>.Instance;
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}
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}
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internal class Never<T> : IUniTaskAsyncEnumerable<T>
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{
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public static readonly IUniTaskAsyncEnumerable<T> Instance = new Never<T>();
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Never()
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{
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}
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public IUniTaskAsyncEnumerator<T> GetAsyncEnumerator(CancellationToken cancellationToken = default)
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{
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return new _Never(cancellationToken);
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}
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class _Never : IUniTaskAsyncEnumerator<T>
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{
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CancellationToken cancellationToken;
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public _Never(CancellationToken cancellationToken)
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{
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this.cancellationToken = cancellationToken;
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}
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public T Current => default;
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public UniTask<bool> MoveNextAsync()
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{
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var tcs = new UniTaskCompletionSource<bool>();
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cancellationToken.Register(state =>
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{
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var task = (UniTaskCompletionSource<bool>)state;
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task.TrySetCanceled(cancellationToken);
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}, tcs);
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return tcs.Task;
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}
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public UniTask DisposeAsync()
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{
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return default;
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}
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}
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}
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}
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