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CrowdControl/Assets/Plugins/UniTask/Runtime/Linq/ElementAt.cs

58 lines
1.8 KiB
C#

using Cysharp.Threading.Tasks.Internal;
using System;
using System.Threading;
namespace Cysharp.Threading.Tasks.Linq
{
public static partial class UniTaskAsyncEnumerable
{
public static UniTask<TSource> ElementAtAsync<TSource>(this IUniTaskAsyncEnumerable<TSource> source, int index, CancellationToken cancellationToken = default)
{
Error.ThrowArgumentNullException(source, nameof(source));
return ElementAt.ElementAtAsync(source, index, cancellationToken, false);
}
public static UniTask<TSource> ElementAtOrDefaultAsync<TSource>(this IUniTaskAsyncEnumerable<TSource> source, int index, CancellationToken cancellationToken = default)
{
Error.ThrowArgumentNullException(source, nameof(source));
return ElementAt.ElementAtAsync(source, index, cancellationToken, true);
}
}
internal static class ElementAt
{
public static async UniTask<TSource> ElementAtAsync<TSource>(IUniTaskAsyncEnumerable<TSource> source, int index, CancellationToken cancellationToken, bool defaultIfEmpty)
{
var e = source.GetAsyncEnumerator(cancellationToken);
try
{
int i = 0;
while (await e.MoveNextAsync())
{
if (i++ == index)
{
return e.Current;
}
}
if (defaultIfEmpty)
{
return default;
}
else
{
throw Error.ArgumentOutOfRange(nameof(index));
}
}
finally
{
if (e != null)
{
await e.DisposeAsync();
}
}
}
}
}