// 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; using System.Collections.Generic; using System.Linq; using System.Threading; using System.Threading.Tasks; namespace System.Linq { public static partial class AsyncEnumerable { public static Task Count(this IAsyncEnumerable source, CancellationToken cancellationToken) { if (source == null) throw new ArgumentNullException(nameof(source)); var collectionoft = source as ICollection; if (collectionoft != null) { return Task.FromResult(collectionoft.Count); } var listProv = source as IIListProvider; if (listProv != null) { return listProv.GetCountAsync(onlyIfCheap: false, cancellationToken: cancellationToken); } return source.Aggregate(0, (c, _) => checked(c + 1), cancellationToken); } public static Task Count(this IAsyncEnumerable source, Func predicate, CancellationToken cancellationToken) { if (source == null) throw new ArgumentNullException(nameof(source)); if (predicate == null) throw new ArgumentNullException(nameof(predicate)); return source.Where(predicate) .Aggregate(0, (c, _) => checked(c + 1), cancellationToken); } public static Task Count(this IAsyncEnumerable source) { if (source == null) throw new ArgumentNullException(nameof(source)); return Count(source, CancellationToken.None); } public static Task Count(this IAsyncEnumerable source, Func predicate) { if (source == null) throw new ArgumentNullException(nameof(source)); if (predicate == null) throw new ArgumentNullException(nameof(predicate)); return Count(source, predicate, CancellationToken.None); } public static Task LongCount(this IAsyncEnumerable source, CancellationToken cancellationToken) { if (source == null) throw new ArgumentNullException(nameof(source)); return source.Aggregate(0L, (c, _) => checked(c + 1), cancellationToken); } public static Task LongCount(this IAsyncEnumerable source, Func predicate, CancellationToken cancellationToken) { if (source == null) throw new ArgumentNullException(nameof(source)); if (predicate == null) throw new ArgumentNullException(nameof(predicate)); return source.Where(predicate) .Aggregate(0L, (c, _) => checked(c + 1), cancellationToken); } public static Task LongCount(this IAsyncEnumerable source) { if (source == null) throw new ArgumentNullException(nameof(source)); return LongCount(source, CancellationToken.None); } public static Task LongCount(this IAsyncEnumerable source, Func predicate) { if (source == null) throw new ArgumentNullException(nameof(source)); if (predicate == null) throw new ArgumentNullException(nameof(predicate)); return LongCount(source, predicate, CancellationToken.None); } } }