using System.Runtime.InteropServices; using System.Security; using System.Threading.Tasks; namespace System.Runtime.CompilerServices { [StructLayout(LayoutKind.Auto)] public struct AsyncValueTaskMethodBuilder<TResult> { private AsyncTaskMethodBuilder<TResult> _methodBuilder; private TResult _result; private bool _haveResult; private bool _useBuilder; public ValueTask<TResult> Task { get { if (_haveResult) return new ValueTask<TResult>(_result); _useBuilder = true; return new ValueTask<TResult>(_methodBuilder.Task); } } public static AsyncValueTaskMethodBuilder<TResult> Create() { AsyncValueTaskMethodBuilder<TResult> result = default(AsyncValueTaskMethodBuilder<TResult>); result._methodBuilder = AsyncTaskMethodBuilder<TResult>.Create(); return result; } public void Start<TStateMachine>(ref TStateMachine stateMachine) where TStateMachine : IAsyncStateMachine { this._methodBuilder.Start(ref stateMachine); } public void SetStateMachine(IAsyncStateMachine stateMachine) { _methodBuilder.SetStateMachine(stateMachine); } public void SetResult(TResult result) { if (_useBuilder) _methodBuilder.SetResult(result); else { _result = result; _haveResult = true; } } public void SetException(Exception exception) { _methodBuilder.SetException(exception); } public void AwaitOnCompleted<TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : INotifyCompletion where TStateMachine : IAsyncStateMachine { this._useBuilder = true; this._methodBuilder.AwaitOnCompleted(ref awaiter, ref stateMachine); } [SecuritySafeCritical] public void AwaitUnsafeOnCompleted<TAwaiter, TStateMachine>(ref TAwaiter awaiter, ref TStateMachine stateMachine) where TAwaiter : ICriticalNotifyCompletion where TStateMachine : IAsyncStateMachine { this._useBuilder = true; this._methodBuilder.AwaitUnsafeOnCompleted(ref awaiter, ref stateMachine); } } }