Fixes #3692++ - Rearchitects drivers (#3837)

Author: tznind

Terminal.Gui/Application/Application.Initialization.cs

@@ -37,7 +37,15 @@ public static partial class Application // Initialization (Init/Shutdown)
     /// </param>
     [RequiresUnreferencedCode ("AOT")]
     [RequiresDynamicCode ("AOT")]
-    public static void Init (IConsoleDriver? driver = null, string? driverName = null) { InternalInit (driver, driverName); }
+    public static void Init (IConsoleDriver? driver = null, string? driverName = null)
+    {
+        if (driverName?.StartsWith ("v2") ?? false)
+        {
+            ApplicationImpl.ChangeInstance (new ApplicationV2 ());
+        }
+
+        ApplicationImpl.Instance.Init (driver, driverName);
+    }
 
     internal static int MainThreadId { get; set; } = -1;
 
@@ -94,19 +102,7 @@ internal static void InternalInit (
 
         AddKeyBindings ();
 
-        // Start the process of configuration management.
-        // Note that we end up calling LoadConfigurationFromAllSources
-        // multiple times. We need to do this because some settings are only
-        // valid after a Driver is loaded. In this case we need just
-        // `Settings` so we can determine which driver to use.
-        // Don't reset, so we can inherit the theme from the previous run.
-        string previousTheme = Themes?.Theme ?? string.Empty;
-        Load ();
-        if (Themes is { } && !string.IsNullOrEmpty (previousTheme) && previousTheme != "Default")
-        {
-            ThemeManager.SelectedTheme = previousTheme;
-        }
-        Apply ();
+        InitializeConfigurationManagement ();
 
         // Ignore Configuration for ForceDriver if driverName is specified
         if (!string.IsNullOrEmpty (driverName))
@@ -166,12 +162,28 @@ internal static void InternalInit (
 
         SynchronizationContext.SetSynchronizationContext (new MainLoopSyncContext ());
 
-        SupportedCultures = GetSupportedCultures ();
         MainThreadId = Thread.CurrentThread.ManagedThreadId;
         bool init = Initialized = true;
         InitializedChanged?.Invoke (null, new (init));
     }
 
+    internal static void InitializeConfigurationManagement ()
+    {
+        // Start the process of configuration management.
+        // Note that we end up calling LoadConfigurationFromAllSources
+        // multiple times. We need to do this because some settings are only
+        // valid after a Driver is loaded. In this case we need just
+        // `Settings` so we can determine which driver to use.
+        // Don't reset, so we can inherit the theme from the previous run.
+        string previousTheme = Themes?.Theme ?? string.Empty;
+        Load ();
+        if (Themes is { } && !string.IsNullOrEmpty (previousTheme) && previousTheme != "Default")
+        {
+            ThemeManager.SelectedTheme = previousTheme;
+        }
+        Apply ();
+    }
+
     internal static void SubscribeDriverEvents ()
     {
         ArgumentNullException.ThrowIfNull (Driver);
@@ -226,20 +238,7 @@ internal static void UnsubscribeDriverEvents ()
     ///     up (Disposed)
     ///     and terminal settings are restored.
     /// </remarks>
-    public static void Shutdown ()
-    {
-        // TODO: Throw an exception if Init hasn't been called.
-
-        bool wasInitialized = Initialized;
-        ResetState ();
-        PrintJsonErrors ();
-
-        if (wasInitialized)
-        {
-            bool init = Initialized;
-            InitializedChanged?.Invoke (null, new (in init));
-        }
-    }
+    public static void Shutdown () => ApplicationImpl.Instance.Shutdown ();
 
     /// <summary>
     ///     Gets whether the application has been initialized with <see cref="Init"/> and not yet shutdown with <see cref="Shutdown"/>.
@@ -258,4 +257,12 @@ public static void Shutdown ()
     ///     Intended to support unit tests that need to know when the application has been initialized.
     /// </remarks>
     public static event EventHandler<EventArgs<bool>>? InitializedChanged;
+
+    /// <summary>
+    ///  Raises the <see cref="InitializedChanged"/> event.
+    /// </summary>
+    internal static void OnInitializedChanged (object sender, EventArgs<bool> e)
+    {
+        Application.InitializedChanged?.Invoke (sender,e);
+    }
 }

Terminal.Gui/Application/Application.Keyboard.cs

@@ -177,7 +177,6 @@ internal static void AddKeyBindings ()
                         return true;
                     }
                    );
-
         AddCommand (
                     Command.Suspend,
                     static () =>
@@ -187,7 +186,6 @@ internal static void AddKeyBindings ()
                         return true;
                     }
                    );
-
         AddCommand (
                     Command.NextTabStop,
                     static () => Navigation?.AdvanceFocus (NavigationDirection.Forward, TabBehavior.TabStop));

Terminal.Gui/Application/Application.Run.cs

@@ -305,7 +305,8 @@ internal static bool PositionCursor ()
     /// <returns>The created <see cref="Toplevel"/> object. The caller is responsible for disposing this object.</returns>
     [RequiresUnreferencedCode ("AOT")]
     [RequiresDynamicCode ("AOT")]
-    public static Toplevel Run (Func<Exception, bool>? errorHandler = null, IConsoleDriver? driver = null) { return Run<Toplevel> (errorHandler, driver); }
+    public static Toplevel Run (Func<Exception, bool>? errorHandler = null, IConsoleDriver? driver = null) =>
+        ApplicationImpl.Instance.Run (errorHandler, driver);
 
     /// <summary>
     ///     Runs the application by creating a <see cref="Toplevel"/>-derived object of type <c>T</c> and calling
@@ -331,20 +332,7 @@ internal static bool PositionCursor ()
     [RequiresUnreferencedCode ("AOT")]
     [RequiresDynamicCode ("AOT")]
     public static T Run<T> (Func<Exception, bool>? errorHandler = null, IConsoleDriver? driver = null)
-        where T : Toplevel, new()
-    {
-        if (!Initialized)
-        {
-            // Init() has NOT been called.
-            InternalInit (driver, null, true);
-        }
-
-        var top = new T ();
-
-        Run (top, errorHandler);
-
-        return top;
-    }
+        where T : Toplevel, new() => ApplicationImpl.Instance.Run<T> (errorHandler, driver);
 
     /// <summary>Runs the Application using the provided <see cref="Toplevel"/> view.</summary>
     /// <remarks>
@@ -385,110 +373,31 @@ public static T Run<T> (Func<Exception, bool>? errorHandler = null, IConsoleDriv
     ///     rethrows when null).
     /// </param>
     public static void Run (Toplevel view, Func<Exception, bool>? errorHandler = null)
-    {
-        ArgumentNullException.ThrowIfNull (view);
-
-        if (Initialized)
-        {
-            if (Driver is null)
-            {
-                // Disposing before throwing
-                view.Dispose ();
-
-                // This code path should be impossible because Init(null, null) will select the platform default driver
-                throw new InvalidOperationException (
-                                                     "Init() completed without a driver being set (this should be impossible); Run<T>() cannot be called."
-                                                    );
-            }
-        }
-        else
-        {
-            // Init() has NOT been called.
-            throw new InvalidOperationException (
-                                                 "Init() has not been called. Only Run() or Run<T>() can be used without calling Init()."
-                                                );
-        }
-
-        var resume = true;
-
-        while (resume)
-        {
-#if !DEBUG
-            try
-            {
-#endif
-            resume = false;
-            RunState runState = Begin (view);
-
-            // If EndAfterFirstIteration is true then the user must dispose of the runToken
-            // by using NotifyStopRunState event.
-            RunLoop (runState);
-
-            if (runState.Toplevel is null)
-            {
-#if DEBUG_IDISPOSABLE
-                Debug.Assert (TopLevels.Count == 0);
-#endif
-                runState.Dispose ();
-
-                return;
-            }
-
-            if (!EndAfterFirstIteration)
-            {
-                End (runState);
-            }
-#if !DEBUG
-            }
-            catch (Exception error)
-            {
-                if (errorHandler is null)
-                {
-                    throw;
-                }
-
-                resume = errorHandler (error);
-            }
-#endif
-        }
-    }
+        => ApplicationImpl.Instance.Run (view, errorHandler);
 
     /// <summary>Adds a timeout to the application.</summary>
     /// <remarks>
     ///     When time specified passes, the callback will be invoked. If the callback returns true, the timeout will be
     ///     reset, repeating the invocation. If it returns false, the timeout will stop and be removed. The returned value is a
     ///     token that can be used to stop the timeout by calling <see cref="RemoveTimeout(object)"/>.
     /// </remarks>
-    public static object? AddTimeout (TimeSpan time, Func<bool> callback)
-    {
-        return MainLoop?.AddTimeout (time, callback) ?? null;
-    }
+    public static object? AddTimeout (TimeSpan time, Func<bool> callback) => ApplicationImpl.Instance.AddTimeout (time, callback);
 
     /// <summary>Removes a previously scheduled timeout</summary>
     /// <remarks>The token parameter is the value returned by <see cref="AddTimeout"/>.</remarks>
     /// Returns
-    /// <c>true</c>
+    /// <see langword="true"/>
     /// if the timeout is successfully removed; otherwise,
-    /// <c>false</c>
+    /// <see langword="false"/>
     /// .
     /// This method also returns
-    /// <c>false</c>
+    /// <see langword="false"/>
     /// if the timeout is not found.
-    public static bool RemoveTimeout (object token) { return MainLoop?.RemoveTimeout (token) ?? false; }
+    public static bool RemoveTimeout (object token) => ApplicationImpl.Instance.RemoveTimeout (token);
 
     /// <summary>Runs <paramref name="action"/> on the thread that is processing events</summary>
     /// <param name="action">the action to be invoked on the main processing thread.</param>
-    public static void Invoke (Action action)
-    {
-        MainLoop?.AddIdle (
-                           () =>
-                           {
-                               action ();
-
-                               return false;
-                           }
-                          );
-    }
+    public static void Invoke (Action action) => ApplicationImpl.Instance.Invoke (action);
 
     // TODO: Determine if this is really needed. The only code that calls WakeUp I can find
     // is ProgressBarStyles, and it's not clear it needs to.
@@ -517,8 +426,7 @@ public static void LayoutAndDraw (bool forceDraw = false)
 
         View.SetClipToScreen ();
         View.Draw (TopLevels, neededLayout || forceDraw);
-        View.SetClipToScreen ();
-
+        View.SetClipToScreen (); 
         Driver?.Refresh ();
     }
 
@@ -528,7 +436,7 @@ public static void LayoutAndDraw (bool forceDraw = false)
 
     /// <summary>The <see cref="MainLoop"/> driver for the application</summary>
     /// <value>The main loop.</value>
-    internal static MainLoop? MainLoop { get; private set; }
+    internal static MainLoop? MainLoop { get; set; }
 
     /// <summary>
     ///     Set to true to cause <see cref="End"/> to be called after the first iteration. Set to false (the default) to
@@ -612,31 +520,8 @@ public static bool RunIteration (ref RunState state, bool firstIteration = false
     ///         property on the currently running <see cref="Toplevel"/> to false.
     ///     </para>
     /// </remarks>
-    public static void RequestStop (Toplevel? top = null)
-    {
-        if (top is null)
-        {
-            top = Top;
-        }
-
-        if (!top!.Running)
-        {
-            return;
-        }
-
-        var ev = new ToplevelClosingEventArgs (top);
-        top.OnClosing (ev);
-
-        if (ev.Cancel)
-        {
-            return;
-        }
-
-        top.Running = false;
-        OnNotifyStopRunState (top);
-    }
-
-    private static void OnNotifyStopRunState (Toplevel top)
+    public static void RequestStop (Toplevel? top = null) => ApplicationImpl.Instance.RequestStop (top);
+    internal static void OnNotifyStopRunState (Toplevel top)
     {
         if (EndAfterFirstIteration)
         {