.NET-Community-Toolkit/CommunityToolkit.Mvvm/Input/RelayCommand.cs

80 lines
2.7 KiB
C#

// 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.
// This file is inspired from the MvvmLight library (lbugnion/MvvmLight),
// more info in ThirdPartyNotices.txt in the root of the project.
using System;
using System.Runtime.CompilerServices;
namespace CommunityToolkit.Mvvm.Input;
/// <summary>
/// A command whose sole purpose is to relay its functionality to other
/// objects by invoking delegates. The default return value for the <see cref="CanExecute"/>
/// method is <see langword="true"/>. This type does not allow you to accept command parameters
/// in the <see cref="Execute"/> and <see cref="CanExecute"/> callback methods.
/// </summary>
public sealed class RelayCommand : IRelayCommand
{
/// <summary>
/// The <see cref="Action"/> to invoke when <see cref="Execute"/> is used.
/// </summary>
private readonly Action execute;
/// <summary>
/// The optional action to invoke when <see cref="CanExecute"/> is used.
/// </summary>
private readonly Func<bool>? canExecute;
/// <inheritdoc/>
public event EventHandler? CanExecuteChanged;
/// <summary>
/// Initializes a new instance of the <see cref="RelayCommand"/> class that can always execute.
/// </summary>
/// <param name="execute">The execution logic.</param>
/// <exception cref="System.ArgumentNullException">Thrown if <paramref name="execute"/> is <see langword="null"/>.</exception>
public RelayCommand(Action execute)
{
ArgumentNullException.ThrowIfNull(execute);
this.execute = execute;
}
/// <summary>
/// Initializes a new instance of the <see cref="RelayCommand"/> class.
/// </summary>
/// <param name="execute">The execution logic.</param>
/// <param name="canExecute">The execution status logic.</param>
/// <exception cref="System.ArgumentNullException">Thrown if <paramref name="execute"/> or <paramref name="canExecute"/> are <see langword="null"/>.</exception>
public RelayCommand(Action execute, Func<bool> canExecute)
{
ArgumentNullException.ThrowIfNull(execute);
ArgumentNullException.ThrowIfNull(canExecute);
this.execute = execute;
this.canExecute = canExecute;
}
/// <inheritdoc/>
public void NotifyCanExecuteChanged()
{
CanExecuteChanged?.Invoke(this, EventArgs.Empty);
}
/// <inheritdoc/>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public bool CanExecute(object? parameter)
{
return this.canExecute?.Invoke() != false;
}
/// <inheritdoc/>
public void Execute(object? parameter)
{
this.execute();
}
}