reactive/Ix.NET/Source/System.Linq.Async/System/Collections/Generic/IAsyncEnumerator.cs

// 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. 

// See https://github.com/dotnet/csharplang/blob/master/proposals/async-streams.md for the definition of this interface
// and the design rationale. (8/30/2017)

#if !HAS_ASYNCENUMERABLE

using System.Threading.Tasks;

namespace System.Collections.Generic
{
    /// <summary>
    /// Asynchronous version of the <see cref="IEnumerator{T}"/> interface, allowing elements to be retrieved asynchronously.
    /// </summary>
    /// <typeparam name="T">Element type.</typeparam>
    public interface IAsyncEnumerator<out T> : IAsyncDisposable
    {
        /// <summary>
        /// Gets the current element in the iteration.
        /// </summary>
        T Current { get; }

        /// <summary>
        /// Advances the enumerator to the next element in the sequence, returning the result asynchronously.
        /// </summary>
        /// <returns>
        /// Task containing the result of the operation: true if the enumerator was successfully advanced
        /// to the next element; false if the enumerator has passed the end of the sequence.
        /// </returns>
        ValueTask<bool> MoveNextAsync();
    }
}

#endif