37 lines
1.7 KiB
C#
37 lines
1.7 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.Windows.Input;
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using CommunityToolkit.Mvvm.Input.Internals;
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namespace CommunityToolkit.Mvvm.Input;
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/// <summary>
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/// Extensions for the <see cref="IAsyncRelayCommand"/> type.
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/// </summary>
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public static class IAsyncRelayCommandExtensions
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{
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/// <summary>
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/// Creates an <see cref="ICommand"/> instance that can be used to cancel execution on the input command.
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/// The returned command will also notify when it can be executed based on the state of the wrapped command.
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/// </summary>
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/// <param name="command">The input <see cref="IAsyncRelayCommand"/> instance to create a cancellation command for.</param>
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/// <returns>An <see cref="ICommand"/> instance that can be used to monitor and signal cancellation for <paramref name="command"/>.</returns>
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/// <remarks>The returned instance is not guaranteed to be unique across multiple invocations with the same arguments.</remarks>
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/// <exception cref="System.ArgumentNullException">Thrown if <paramref name="command"/> is <see langword="null"/>.</exception>
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public static ICommand CreateCancelCommand(this IAsyncRelayCommand command)
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{
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ArgumentNullException.ThrowIfNull(command);
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// If the command is known not to ever allow cancellation, just reuse the same instance
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if (command is ICancellationAwareCommand { IsCancellationSupported: false })
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{
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return DisabledCommand.Instance;
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}
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// Create a new cancel command wrapping the input one
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return new CancelCommand(command);
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}
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}
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