using Cysharp.Threading.Tasks.Internal;
|
using System;
|
using System.Threading;
|
|
namespace Cysharp.Threading.Tasks.Linq
|
{
|
public static partial class UniTaskAsyncEnumerable
|
{
|
public static IUniTaskAsyncEnumerable<TSource> Append<TSource>(this IUniTaskAsyncEnumerable<TSource> source, TSource element)
|
{
|
Error.ThrowArgumentNullException(source, nameof(source));
|
|
return new AppendPrepend<TSource>(source, element, true);
|
}
|
|
public static IUniTaskAsyncEnumerable<TSource> Prepend<TSource>(this IUniTaskAsyncEnumerable<TSource> source, TSource element)
|
{
|
Error.ThrowArgumentNullException(source, nameof(source));
|
|
return new AppendPrepend<TSource>(source, element, false);
|
}
|
}
|
|
internal sealed class AppendPrepend<TSource> : IUniTaskAsyncEnumerable<TSource>
|
{
|
readonly IUniTaskAsyncEnumerable<TSource> source;
|
readonly TSource element;
|
readonly bool append; // or prepend
|
|
public AppendPrepend(IUniTaskAsyncEnumerable<TSource> source, TSource element, bool append)
|
{
|
this.source = source;
|
this.element = element;
|
this.append = append;
|
}
|
|
public IUniTaskAsyncEnumerator<TSource> GetAsyncEnumerator(CancellationToken cancellationToken = default)
|
{
|
return new _AppendPrepend(source, element, append, cancellationToken);
|
}
|
|
sealed class _AppendPrepend : MoveNextSource, IUniTaskAsyncEnumerator<TSource>
|
{
|
enum State : byte
|
{
|
None,
|
RequirePrepend,
|
RequireAppend,
|
Completed
|
}
|
|
static readonly Action<object> MoveNextCoreDelegate = MoveNextCore;
|
|
readonly IUniTaskAsyncEnumerable<TSource> source;
|
readonly TSource element;
|
CancellationToken cancellationToken;
|
|
State state;
|
IUniTaskAsyncEnumerator<TSource> enumerator;
|
UniTask<bool>.Awaiter awaiter;
|
|
public _AppendPrepend(IUniTaskAsyncEnumerable<TSource> source, TSource element, bool append, CancellationToken cancellationToken)
|
{
|
this.source = source;
|
this.element = element;
|
this.state = append ? State.RequireAppend : State.RequirePrepend;
|
this.cancellationToken = cancellationToken;
|
|
TaskTracker.TrackActiveTask(this, 3);
|
}
|
|
public TSource Current { get; private set; }
|
|
|
public UniTask<bool> MoveNextAsync()
|
{
|
cancellationToken.ThrowIfCancellationRequested();
|
completionSource.Reset();
|
|
if (enumerator == null)
|
{
|
if (state == State.RequirePrepend)
|
{
|
Current = element;
|
state = State.None;
|
return CompletedTasks.True;
|
}
|
|
enumerator = source.GetAsyncEnumerator(cancellationToken);
|
}
|
|
if (state == State.Completed)
|
{
|
return CompletedTasks.False;
|
}
|
|
awaiter = enumerator.MoveNextAsync().GetAwaiter();
|
|
if (awaiter.IsCompleted)
|
{
|
MoveNextCoreDelegate(this);
|
}
|
else
|
{
|
awaiter.SourceOnCompleted(MoveNextCoreDelegate, this);
|
}
|
|
return new UniTask<bool>(this, completionSource.Version);
|
}
|
|
static void MoveNextCore(object state)
|
{
|
var self = (_AppendPrepend)state;
|
|
if (self.TryGetResult(self.awaiter, out var result))
|
{
|
if (result)
|
{
|
self.Current = self.enumerator.Current;
|
self.completionSource.TrySetResult(true);
|
}
|
else
|
{
|
if (self.state == State.RequireAppend)
|
{
|
self.state = State.Completed;
|
self.Current = self.element;
|
self.completionSource.TrySetResult(true);
|
}
|
else
|
{
|
self.state = State.Completed;
|
self.completionSource.TrySetResult(false);
|
}
|
}
|
}
|
}
|
|
public UniTask DisposeAsync()
|
{
|
TaskTracker.RemoveTracking(this);
|
if (enumerator != null)
|
{
|
return enumerator.DisposeAsync();
|
}
|
return default;
|
}
|
}
|
}
|
|
}
|
