Refactor terminal startup method

CHANGES.md

@@ -30,7 +30,8 @@ To be Released.
 * Removed commands sorting code in `CommandContextBase`.  [[#38]]
 * Integrated usage-related properties(`Summary`, `Description`, `Example`) into 
   the `CommandUsage` property.  [[#40]]
-* Added ₩StepProgress₩ to make it easier to work with progress.  [[#41]]
+* Added `StepProgress` to make it easier to work with progress.  [[#41]]
+* Added `RunAsync` and `StopAsync` methods to `SystemTerminalBase`.  [[#42]]
 
 [#13]: https://github.com/s2quake/commands/pull/13
 [#17]: https://github.com/s2quake/commands/pull/17
@@ -48,6 +49,7 @@ To be Released.
 [#38]: https://github.com/s2quake/commands/pull/38
 [#40]: https://github.com/s2quake/commands/pull/40
 [#41]: https://github.com/s2quake/commands/pull/41
+[#42]: https://github.com/s2quake/commands/pull/42
 
 
 6.0.1

example/JSSoft.Commands.Repl/Application.cs

@@ -76,7 +76,7 @@ public Task StartAsync()
 
         _terminal = _container.GetExportedValue<SystemTerminal>();
         _cancellationTokenSource = new();
-        return _terminal.StartAsync(_cancellationTokenSource.Token);
+        return _terminal.RunAsync(_cancellationTokenSource.Token);
     }
 
     public void Dispose()

src/JSSoft.Terminals/SystemTerminalBase.cs

@@ -22,6 +22,8 @@ public abstract class SystemTerminalBase : IDisposable
     private readonly TextWriter _error;
     private string _prompt = string.Empty;
     private bool _isDisposed;
+    private CancellationTokenSource? _cancellationTokenSource;
+    private Task? _runningTask;
 
     protected SystemTerminalBase()
     {
@@ -44,20 +46,50 @@ protected SystemTerminalBase()
 
     public async Task StartAsync(CancellationToken cancellationToken)
     {
+        if (_cancellationTokenSource is not null)
+        {
+            throw new InvalidOperationException("The terminal is already running.");
+        }
+
+        _cancellationTokenSource = new CancellationTokenSource();
         OnInitialize(_out, _error);
+        _runningTask = Task.Run(() => ProcessAsync(_cancellationTokenSource.Token), default);
+        await Task.CompletedTask;
+    }
+
+    public async Task StopAsync(CancellationToken cancellationToken)
+    {
+        if (_cancellationTokenSource is null)
+        {
+            throw new InvalidOperationException("The terminal is not running.");
+        }
 
+        _cancellationTokenSource.Cancel();
+        if (_runningTask is not null)
+        {
+            await _runningTask;
+        }
+
+        _cancellationTokenSource.Dispose();
+        _cancellationTokenSource = null;
+    }
+
+    public async Task RunAsync(CancellationToken cancellationToken)
+    {
+        await StartAsync(cancellationToken);
         while (cancellationToken.IsCancellationRequested is false)
         {
-            var isEnabled = _terminal.IsEnabled;
-            var prompt = Prompt;
-            if (isEnabled is true && _terminal.ReadStringInternal(prompt, cancellationToken) is { } text)
+            try
             {
-                await ExecuteAsync(_error, text);
+                await Task.Delay(1, default);
+            }
+            catch (TaskCanceledException)
+            {
+                break;
             }
-#pragma warning disable CA2016
-            await Task.Delay(1);
-#pragma warning restore
         }
+
+        await StopAsync(cancellationToken);
     }
 
     public string? ReadString(string prompt, string command) => _terminal.ReadString(prompt, command);
@@ -116,6 +148,27 @@ protected virtual void OnDispose()
 
     protected abstract Task OnExecuteAsync(string command, CancellationToken cancellationToken);
 
+    private async Task ProcessAsync(CancellationToken cancellationToken)
+    {
+        while (cancellationToken.IsCancellationRequested is false)
+        {
+            var isEnabled = _terminal.IsEnabled;
+            var prompt = Prompt;
+            if (isEnabled is true && _terminal.ReadStringInternal(prompt, cancellationToken) is { } text)
+            {
+                await ExecuteAsync(_error, text);
+            }
+            try
+            {
+                await Task.Delay(1, default);
+            }
+            catch (TaskCanceledException)
+            {
+                break;
+            }
+        }
+    }
+
     private async Task ExecuteAsync(TextWriter error, string text)
     {
         var consoleControlC = Console.IsInputRedirected is false && Console.TreatControlCAsInput;