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

128 lines
4.1 KiB
C#

using Cysharp.Threading.Tasks.Internal;
using System;
using System.Threading;
namespace Cysharp.Threading.Tasks.Linq
{
public static partial class UniTaskAsyncEnumerable
{
public static IUniTaskAsyncEnumerable<(TSource, TSource)> Pairwise<TSource>(this IUniTaskAsyncEnumerable<TSource> source)
{
Error.ThrowArgumentNullException(source, nameof(source));
return new Pairwise<TSource>(source);
}
}
internal sealed class Pairwise<TSource> : IUniTaskAsyncEnumerable<(TSource, TSource)>
{
readonly IUniTaskAsyncEnumerable<TSource> source;
public Pairwise(IUniTaskAsyncEnumerable<TSource> source)
{
this.source = source;
}
public IUniTaskAsyncEnumerator<(TSource, TSource)> GetAsyncEnumerator(CancellationToken cancellationToken = default)
{
return new _Pairwise(source, cancellationToken);
}
sealed class _Pairwise : MoveNextSource, IUniTaskAsyncEnumerator<(TSource, TSource)>
{
static readonly Action<object> MoveNextCoreDelegate = MoveNextCore;
readonly IUniTaskAsyncEnumerable<TSource> source;
CancellationToken cancellationToken;
IUniTaskAsyncEnumerator<TSource> enumerator;
UniTask<bool>.Awaiter awaiter;
TSource prev;
bool isFirst;
public _Pairwise(IUniTaskAsyncEnumerable<TSource> source, CancellationToken cancellationToken)
{
this.source = source;
this.cancellationToken = cancellationToken;
TaskTracker.TrackActiveTask(this, 3);
}
public (TSource, TSource) Current { get; private set; }
public UniTask<bool> MoveNextAsync()
{
cancellationToken.ThrowIfCancellationRequested();
if (enumerator == null)
{
isFirst = true;
enumerator = source.GetAsyncEnumerator(cancellationToken);
}
completionSource.Reset();
SourceMoveNext();
return new UniTask<bool>(this, completionSource.Version);
}
void SourceMoveNext()
{
try
{
awaiter = enumerator.MoveNextAsync().GetAwaiter();
if (awaiter.IsCompleted)
{
MoveNextCore(this);
}
else
{
awaiter.SourceOnCompleted(MoveNextCoreDelegate, this);
}
}
catch (Exception ex)
{
completionSource.TrySetException(ex);
}
}
static void MoveNextCore(object state)
{
var self = (_Pairwise)state;
if (self.TryGetResult(self.awaiter, out var result))
{
if (result)
{
if (self.isFirst)
{
self.isFirst = false;
self.prev = self.enumerator.Current;
self.SourceMoveNext(); // run again. okay to use recursive(only one more).
}
else
{
var p = self.prev;
self.prev = self.enumerator.Current;
self.Current = (p, self.prev);
self.completionSource.TrySetResult(true);
}
}
else
{
self.completionSource.TrySetResult(false);
}
}
}
public UniTask DisposeAsync()
{
TaskTracker.RemoveTracking(this);
if (enumerator != null)
{
return enumerator.DisposeAsync();
}
return default;
}
}
}
}