67 lines
2.8 KiB
C#
67 lines
2.8 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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using System;
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using System.Linq;
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using System.Threading;
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using System.Threading.Tasks;
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namespace CommunityToolkit.Common.Deferred;
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/// <summary>
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/// Extensions to <see cref="EventHandler{TEventArgs}"/> for Deferred Events.
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/// </summary>
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public static class EventHandlerExtensions
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{
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/// <summary>
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/// Use to invoke an async <see cref="EventHandler{TEventArgs}"/> using <see cref="DeferredEventArgs"/>.
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/// </summary>
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/// <typeparam name="T"><see cref="EventArgs"/> type.</typeparam>
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/// <param name="eventHandler"><see cref="EventHandler{TEventArgs}"/> to be invoked.</param>
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/// <param name="sender">Sender of the event.</param>
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/// <param name="eventArgs"><see cref="EventArgs"/> instance.</param>
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/// <returns><see cref="Task"/> to wait on deferred event handler.</returns>
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public static Task InvokeAsync<T>(this EventHandler<T>? eventHandler, object sender, T eventArgs)
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where T : DeferredEventArgs
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{
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return InvokeAsync(eventHandler, sender, eventArgs, CancellationToken.None);
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}
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/// <summary>
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/// Use to invoke an async <see cref="EventHandler{TEventArgs}"/> using <see cref="DeferredEventArgs"/> with a <see cref="CancellationToken"/>.
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/// </summary>
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/// <typeparam name="T"><see cref="EventArgs"/> type.</typeparam>
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/// <param name="eventHandler"><see cref="EventHandler{TEventArgs}"/> to be invoked.</param>
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/// <param name="sender">Sender of the event.</param>
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/// <param name="eventArgs"><see cref="EventArgs"/> instance.</param>
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/// <param name="cancellationToken"><see cref="CancellationToken"/> option.</param>
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/// <returns><see cref="Task"/> to wait on deferred event handler.</returns>
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public static Task InvokeAsync<T>(this EventHandler<T>? eventHandler, object sender, T eventArgs, CancellationToken cancellationToken)
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where T : DeferredEventArgs
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{
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if (eventHandler == null)
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{
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return Task.CompletedTask;
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}
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Task[]? tasks = eventHandler.GetInvocationList()
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.OfType<EventHandler<T>>()
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.Select(invocationDelegate =>
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{
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cancellationToken.ThrowIfCancellationRequested();
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invocationDelegate(sender, eventArgs);
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#pragma warning disable CS0618 // Type or member is obsolete
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EventDeferral? deferral = eventArgs.GetCurrentDeferralAndReset();
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return deferral?.WaitForCompletion(cancellationToken) ?? Task.CompletedTask;
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#pragma warning restore CS0618 // Type or member is obsolete
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})
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.ToArray();
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return Task.WhenAll(tasks);
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}
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}
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