| | | 1 | | // ----------------------------------------------------------------------- |
| | | 2 | | // <copyright file="AsyncRelayCommand.cs" company="Stéphane ANDRE"> |
| | | 3 | | // Copyright (c) Stéphane ANDRE. All rights reserved. |
| | | 4 | | // </copyright> |
| | | 5 | | // ----------------------------------------------------------------------- |
| | | 6 | | |
| | | 7 | | using System; |
| | | 8 | | using System.Diagnostics.CodeAnalysis; |
| | | 9 | | using System.Reactive.Concurrency; |
| | | 10 | | using System.Threading; |
| | | 11 | | using System.Threading.Tasks; |
| | | 12 | | using System.Windows.Input; |
| | | 13 | | using MyNet.UI.Threading; |
| | | 14 | | |
| | | 15 | | namespace MyNet.UI.Commands; |
| | | 16 | | |
| | | 17 | | /// <summary> |
| | | 18 | | /// An implementation of <see cref="IAsyncCommand"/> that relays its functionality to the provided asynchronous delegate |
| | | 19 | | /// </summary> |
| | | 20 | | /// <param name="execute">The asynchronous delegate to execute when the command is invoked.</param> |
| | | 21 | | /// <param name="canExecute">An optional delegate to determine whether the command can execute.</param> |
| | | 22 | | /// <param name="schedulerProvider">An optional scheduler provider to specify the UI thread scheduler.</param> |
| | | 23 | | public sealed class AsyncRelayCommand(Func<Task> execute, Func<bool>? canExecute = null, ISchedulerProvider? schedulerPr |
| | | 24 | | { |
| | 357 | 25 | | private readonly Func<Task> _execute = execute ?? throw new ArgumentNullException(nameof(execute)); |
| | 357 | 26 | | private readonly IScheduler _uiScheduler = schedulerProvider?.Ui ?? CurrentThreadScheduler.Instance; |
| | | 27 | | private int _isExecuting; |
| | | 28 | | |
| | | 29 | | /// <summary> |
| | | 30 | | /// Gets the event that is raised when the return value of the CanExecute method changes. This event should be raise |
| | | 31 | | /// </summary> |
| | | 32 | | public event EventHandler? CanExecuteChanged; |
| | | 33 | | |
| | | 34 | | /// <summary> |
| | | 35 | | /// Determines whether the command can execute in its current state. The command can execute if it is not currently |
| | | 36 | | /// </summary> |
| | | 37 | | /// <param name="parameter">The command parameter.</param> |
| | | 38 | | /// <returns><see langword="true"/> if the command can execute; otherwise, <see langword="false"/>.</returns> |
| | 27 | 39 | | public bool CanExecute(object? parameter) => Volatile.Read(ref _isExecuting) == 0 && (canExecute?.Invoke() ?? true); |
| | | 40 | | |
| | | 41 | | /// <summary> |
| | | 42 | | /// Asynchronously executes the command. If the command cannot execute, this method does nothing. This method is thr |
| | | 43 | | /// </summary> |
| | | 44 | | /// <param name="parameter">The command parameter.</param> |
| | | 45 | | public async Task ExecuteAsync(object? parameter) |
| | | 46 | | { |
| | 15 | 47 | | if (!CanExecute(parameter) || Interlocked.CompareExchange(ref _isExecuting, 1, 0) != 0) |
| | 3 | 48 | | return; |
| | | 49 | | |
| | | 50 | | try |
| | | 51 | | { |
| | 12 | 52 | | RaiseCanExecuteChanged(); |
| | | 53 | | |
| | 12 | 54 | | await _execute().ConfigureAwait(false); |
| | 12 | 55 | | } |
| | | 56 | | finally |
| | | 57 | | { |
| | 12 | 58 | | Interlocked.Exchange(ref _isExecuting, 0); |
| | 12 | 59 | | RaiseCanExecuteChanged(); |
| | | 60 | | } |
| | 15 | 61 | | } |
| | | 62 | | |
| | | 63 | | /// <summary> |
| | | 64 | | /// Asynchronously executes the command. This method is required by the ICommand interface and simply calls the Exec |
| | | 65 | | /// </summary> |
| | | 66 | | /// <param name="parameter">The command parameter.</param> |
| | | 67 | | [SuppressMessage("ReSharper", "AsyncVoidMethod", Justification = "Required by ICommand interface.")] |
| | 0 | 68 | | async void ICommand.Execute(object? parameter) => await ExecuteAsync(parameter).ConfigureAwait(false); |
| | | 69 | | |
| | | 70 | | /// <summary> |
| | | 71 | | /// Raises the CanExecuteChanged event to indicate that the return value of the CanExecute method has changed. This |
| | | 72 | | /// </summary> |
| | 27 | 73 | | public void RaiseCanExecuteChanged() => _uiScheduler.Schedule(() => CanExecuteChanged?.Invoke(this, EventArgs.Empty) |
| | | 74 | | } |
| | | 75 | | |
| | | 76 | | /// <summary> |
| | | 77 | | /// An implementation of <see cref="IAsyncCommand"/> that relays its functionality to the provided asynchronous delegate |
| | | 78 | | /// </summary> |
| | | 79 | | /// <param name="execute">The asynchronous delegate to execute when the command is invoked.</param> |
| | | 80 | | /// <param name="canExecute">The delegate that determines whether the command can execute.</param> |
| | | 81 | | /// <param name="schedulerProvider">The scheduler provider for UI thread scheduling.</param> |
| | | 82 | | /// <typeparam name="T">The type of the command parameter.</typeparam> |
| | | 83 | | public sealed class AsyncRelayCommand<T>(Func<T?, Task> execute, Func<T?, bool>? canExecute = null, ISchedulerProvider? |
| | | 84 | | { |
| | | 85 | | private readonly Func<T?, Task> _execute = execute ?? throw new ArgumentNullException(nameof(execute)); |
| | | 86 | | private readonly IScheduler _uiScheduler = schedulerProvider?.Ui ?? CurrentThreadScheduler.Instance; |
| | | 87 | | private int _isExecuting; |
| | | 88 | | |
| | | 89 | | /// <summary> |
| | | 90 | | /// Gets the event that is raised when the return value of the CanExecute method changes. This event should be raise |
| | | 91 | | /// </summary> |
| | | 92 | | public event EventHandler? CanExecuteChanged; |
| | | 93 | | |
| | | 94 | | /// <summary> |
| | | 95 | | /// Determines whether the command can execute in its current state. The command can execute if it is not currently |
| | | 96 | | /// </summary> |
| | | 97 | | /// <param name="parameter">The command parameter.</param> |
| | | 98 | | /// <returns>True if the command can execute; otherwise, false.</returns> |
| | | 99 | | public bool CanExecute(object? parameter) |
| | | 100 | | => Volatile.Read(ref _isExecuting) == 0 |
| | | 101 | | && (parameter is T or null) |
| | | 102 | | && (canExecute?.Invoke((T?)parameter) ?? true); |
| | | 103 | | |
| | | 104 | | /// <summary> |
| | | 105 | | /// Asynchronously executes the command. If the command cannot execute, this method does nothing. This method is thr |
| | | 106 | | /// </summary> |
| | | 107 | | /// <param name="parameter">The command parameter.</param> |
| | | 108 | | /// <returns>A task that represents the asynchronous operation.</returns> |
| | | 109 | | public async Task ExecuteAsync(object? parameter) |
| | | 110 | | { |
| | | 111 | | if (!CanExecute(parameter) || Interlocked.CompareExchange(ref _isExecuting, 1, 0) != 0) |
| | | 112 | | return; |
| | | 113 | | |
| | | 114 | | try |
| | | 115 | | { |
| | | 116 | | RaiseCanExecuteChanged(); |
| | | 117 | | await _execute((T?)parameter).ConfigureAwait(false); |
| | | 118 | | } |
| | | 119 | | finally |
| | | 120 | | { |
| | | 121 | | Interlocked.Exchange(ref _isExecuting, 0); |
| | | 122 | | RaiseCanExecuteChanged(); |
| | | 123 | | } |
| | | 124 | | } |
| | | 125 | | |
| | | 126 | | /// <summary> |
| | | 127 | | /// Asynchronously executes the command. This method is required by the ICommand interface and simply calls the Exec |
| | | 128 | | /// </summary> |
| | | 129 | | /// <param name="parameter">The command parameter.</param> |
| | | 130 | | [SuppressMessage("ReSharper", "AsyncVoidMethod", Justification = "Required by ICommand interface.")] |
| | | 131 | | async void ICommand.Execute(object? parameter) => await ExecuteAsync(parameter).ConfigureAwait(false); |
| | | 132 | | |
| | | 133 | | /// <summary> |
| | | 134 | | /// Raises the CanExecuteChanged event to indicate that the return value of the CanExecute method has changed. This |
| | | 135 | | /// </summary> |
| | | 136 | | public void RaiseCanExecuteChanged() => _uiScheduler.Schedule(() => CanExecuteChanged?.Invoke(this, EventArgs.Empty) |
| | | 137 | | } |
| | | 138 | | |