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OnErrorResumeNext.cs
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OnErrorResumeNext.cs
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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the Apache 2.0 License.
// See the LICENSE file in the project root for more information.
using System.Collections.Generic;
using System.Threading.Tasks;
namespace System.Linq
{
public static partial class AsyncEnumerableEx
{
public static IAsyncEnumerable<TSource> OnErrorResumeNext<TSource>(this IAsyncEnumerable<TSource> first, IAsyncEnumerable<TSource> second)
{
if (first == null)
throw Error.ArgumentNull(nameof(first));
if (second == null)
throw Error.ArgumentNull(nameof(second));
return OnErrorResumeNextCore(new[] { first, second });
}
public static IAsyncEnumerable<TSource> OnErrorResumeNext<TSource>(params IAsyncEnumerable<TSource>[] sources)
{
if (sources == null)
throw Error.ArgumentNull(nameof(sources));
return OnErrorResumeNextCore(sources);
}
public static IAsyncEnumerable<TSource> OnErrorResumeNext<TSource>(this IEnumerable<IAsyncEnumerable<TSource>> sources)
{
if (sources == null)
throw Error.ArgumentNull(nameof(sources));
return OnErrorResumeNextCore(sources);
}
private static IAsyncEnumerable<TSource> OnErrorResumeNextCore<TSource>(IEnumerable<IAsyncEnumerable<TSource>> sources)
{
return new OnErrorResumeNextAsyncIterator<TSource>(sources);
}
private sealed class OnErrorResumeNextAsyncIterator<TSource> : AsyncIterator<TSource>
{
private readonly IEnumerable<IAsyncEnumerable<TSource>> _sources;
private IAsyncEnumerator<TSource>? _enumerator;
private IEnumerator<IAsyncEnumerable<TSource>>? _sourcesEnumerator;
public OnErrorResumeNextAsyncIterator(IEnumerable<IAsyncEnumerable<TSource>> sources)
{
_sources = sources;
}
public override AsyncIteratorBase<TSource> Clone()
{
return new OnErrorResumeNextAsyncIterator<TSource>(_sources);
}
public override async ValueTask DisposeAsync()
{
if (_sourcesEnumerator != null)
{
_sourcesEnumerator.Dispose();
_sourcesEnumerator = null;
}
if (_enumerator != null)
{
await _enumerator.DisposeAsync().ConfigureAwait(false);
_enumerator = null;
}
await base.DisposeAsync().ConfigureAwait(false);
}
protected override async ValueTask<bool> MoveNextCore()
{
switch (_state)
{
case AsyncIteratorState.Allocated:
_sourcesEnumerator = _sources.GetEnumerator();
_state = AsyncIteratorState.Iterating;
goto case AsyncIteratorState.Iterating;
case AsyncIteratorState.Iterating:
while (true)
{
if (_enumerator == null)
{
if (!_sourcesEnumerator!.MoveNext())
{
break; // while -- done, nothing else to do
}
_enumerator = _sourcesEnumerator.Current.GetAsyncEnumerator(_cancellationToken);
}
try
{
if (await _enumerator.MoveNextAsync().ConfigureAwait(false))
{
_current = _enumerator.Current;
return true;
}
}
catch
{
// Ignore
}
// Done with the current one, go to the next
await _enumerator.DisposeAsync().ConfigureAwait(false);
_enumerator = null;
}
break; // case
}
await DisposeAsync().ConfigureAwait(false);
return false;
}
}
}
}