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- // Licensed to the .NET Foundation under one or more agreements.
- // The .NET Foundation licenses this file to you under the MIT License.
- // See the LICENSE file in the project root for more information.
- using System.Threading.Tasks;
- namespace System.Reactive.Linq
- {
- public partial class AsyncObservable
- {
- public static IAsyncObservable<TSource> FirstAsync<TSource>(this IAsyncObservable<TSource> source) => First(source);
- public static IAsyncObservable<TSource> FirstAsync<TSource>(this IAsyncObservable<TSource> source, Func<TSource, bool> predicate) => First(source, predicate);
- public static IAsyncObservable<TSource> FirstAsync<TSource>(this IAsyncObservable<TSource> source, Func<TSource, ValueTask<bool>> predicate) => First(source, predicate);
- public static IAsyncObservable<TSource> First<TSource>(this IAsyncObservable<TSource> source)
- {
- if (source == null)
- throw new ArgumentNullException(nameof(source));
- return Create(source, static (source, observer) => source.SubscribeSafeAsync(AsyncObserver.First(observer)));
- }
- public static IAsyncObservable<TSource> First<TSource>(this IAsyncObservable<TSource> source, Func<TSource, bool> predicate)
- {
- if (source == null)
- throw new ArgumentNullException(nameof(source));
- if (predicate == null)
- throw new ArgumentNullException(nameof(predicate));
- return Create(
- source,
- predicate,
- static (source, predicate, observer) => source.SubscribeSafeAsync(AsyncObserver.First(observer, predicate)));
- }
- public static IAsyncObservable<TSource> First<TSource>(this IAsyncObservable<TSource> source, Func<TSource, ValueTask<bool>> predicate)
- {
- if (source == null)
- throw new ArgumentNullException(nameof(source));
- if (predicate == null)
- throw new ArgumentNullException(nameof(predicate));
- return Create(
- source,
- predicate,
- static (source, predicate, observer) => source.SubscribeSafeAsync(AsyncObserver.First(observer, predicate)));
- }
- }
- public partial class AsyncObserver
- {
- public static IAsyncObserver<TSource> First<TSource>(IAsyncObserver<TSource> observer)
- {
- if (observer == null)
- throw new ArgumentNullException(nameof(observer));
- return Create<TSource>(
- async x =>
- {
- await observer.OnNextAsync(x).ConfigureAwait(false);
- await observer.OnCompletedAsync().ConfigureAwait(false);
- },
- observer.OnErrorAsync,
- async () =>
- {
- await observer.OnErrorAsync(new InvalidOperationException("The sequence is empty.")).ConfigureAwait(false);
- }
- );
- }
- public static IAsyncObserver<TSource> First<TSource>(IAsyncObserver<TSource> observer, Func<TSource, bool> predicate)
- {
- if (observer == null)
- throw new ArgumentNullException(nameof(observer));
- if (predicate == null)
- throw new ArgumentNullException(nameof(predicate));
- return Where(First(observer), predicate);
- }
- public static IAsyncObserver<TSource> First<TSource>(IAsyncObserver<TSource> observer, Func<TSource, ValueTask<bool>> predicate)
- {
- if (observer == null)
- throw new ArgumentNullException(nameof(observer));
- if (predicate == null)
- throw new ArgumentNullException(nameof(predicate));
- return Where(First(observer), predicate);
- }
- }
- }
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