Start fixing null-ability

Terminal.Gui/ConsoleDrivers/AnsiEscapeSequence.cs

@@ -0,0 +1,49 @@
+#nullable enable
+namespace Terminal.Gui;
+
+/// <summary>
+/// Describes an Ansi escape sequence. This is a 'blueprint'. If you
+/// want to send the sequence you should instead use <see cref="AnsiEscapeSequenceRequest"/>
+/// </summary>
+public class AnsiEscapeSequence
+{
+    /// <summary>
+    ///     Request to send e.g. see
+    ///     <see>
+    ///         <cref>EscSeqUtils.CSI_SendDeviceAttributes.Request</cref>
+    ///     </see>
+    /// </summary>
+    public required string Request { get; init; }
+
+    /// <summary>
+    ///     <para>
+    ///         The terminator that uniquely identifies the type of response as responded
+    ///         by the console. e.g. for
+    ///         <see>
+    ///             <cref>EscSeqUtils.CSI_SendDeviceAttributes.Request</cref>
+    ///         </see>
+    ///         the terminator is
+    ///         <see>
+    ///             <cref>EscSeqUtils.CSI_SendDeviceAttributes.Terminator</cref>
+    ///         </see>
+    ///         .
+    ///     </para>
+    ///     <para>
+    ///         After sending a request, the first response with matching terminator will be matched
+    ///         to the oldest outstanding request.
+    ///     </para>
+    /// </summary>
+    public required string Terminator { get; init; }
+
+
+
+    /// <summary>
+    ///     The value expected in the response e.g.
+    ///     <see>
+    ///         <cref>EscSeqUtils.CSI_ReportTerminalSizeInChars.Value</cref>
+    ///     </see>
+    ///     which will have a 't' as terminator but also other different request may return the same terminator with a
+    ///     different value.
+    /// </summary>
+    public string? Value { get; init; }
+}

Terminal.Gui/ConsoleDrivers/AnsiEscapeSequenceRequest.cs

@@ -6,47 +6,19 @@ namespace Terminal.Gui;
 ///     Use <see cref="ResponseReceived"/> to handle the response
 ///     when console answers the request.
 /// </summary>
-public class AnsiEscapeSequenceRequest
+public class AnsiEscapeSequenceRequest : AnsiEscapeSequence
 {
-    /// <summary>
-    ///     Request to send e.g. see
-    ///     <see>
-    ///         <cref>EscSeqUtils.CSI_SendDeviceAttributes.Request</cref>
-    ///     </see>
-    /// </summary>
-    public required string Request { get; init; }
-
-    // BUGBUG: Nullable issue
     /// <summary>
     ///     Invoked when the console responds with an ANSI response code that matches the
-    ///     <see cref="Terminator"/>
+    ///     <see cref="AnsiEscapeSequence.Terminator"/>
     /// </summary>
-    public Action<string> ResponseReceived;
+    public required Action<string> ResponseReceived { get; init; }
 
     /// <summary>
     ///     Invoked if the console fails to responds to the ANSI response code
     /// </summary>
-    public Action? Abandoned;
+    public Action? Abandoned { get; init; }
 
-    /// <summary>
-    ///     <para>
-    ///         The terminator that uniquely identifies the type of response as responded
-    ///         by the console. e.g. for
-    ///         <see>
-    ///             <cref>EscSeqUtils.CSI_SendDeviceAttributes.Request</cref>
-    ///         </see>
-    ///         the terminator is
-    ///         <see>
-    ///             <cref>EscSeqUtils.CSI_SendDeviceAttributes.Terminator</cref>
-    ///         </see>
-    ///         .
-    ///     </para>
-    ///     <para>
-    ///         After sending a request, the first response with matching terminator will be matched
-    ///         to the oldest outstanding request.
-    ///     </para>
-    /// </summary>
-    public required string Terminator { get; init; }
 
     /// <summary>
     ///     Sends the <see cref="Request"/> to the raw output stream of the current <see cref="ConsoleDriver"/>.
@@ -55,14 +27,4 @@ public class AnsiEscapeSequenceRequest
     /// </summary>
     public void Send () { Application.Driver?.WriteRaw (Request); }
 
-
-    /// <summary>
-    ///     The value expected in the response e.g.
-    ///     <see>
-    ///         <cref>EscSeqUtils.CSI_ReportTerminalSizeInChars.Value</cref>
-    ///     </see>
-    ///     which will have a 't' as terminator but also other different request may return the same terminator with a
-    ///     different value.
-    /// </summary>
-    public string? Value { get; init; }
 }

Terminal.Gui/ConsoleDrivers/CursesDriver/CursesDriver.cs

@@ -581,8 +581,7 @@ internal class CursesDriver : ConsoleDriver
 
     private Curses.Window? _window;
     private UnixMainLoop? _mainLoopDriver;
-    // BUGBUG: Fix this nullable issue.
-    private object _processInputToken;
+    private object? _processInputToken;
 
     public override MainLoop Init ()
     {
@@ -1111,7 +1110,7 @@ internal class CursesDriver : ConsoleDriver
         StopReportingMouseMoves ();
         SetCursorVisibility (CursorVisibility.Default);
 
-        if (_mainLoopDriver is { })
+        if (_mainLoopDriver is { } && _processInputToken != null)
         {
             _mainLoopDriver.RemoveWatch (_processInputToken);
         }

Terminal.Gui/ConsoleDrivers/EscSeqUtils/EscSeqUtils.cs

@@ -1799,7 +1799,7 @@ public static class EscSeqUtils
     ///     https://terminalguide.namepad.de/seq/csi_sn__p-6/
     ///     The terminal reply to <see cref="CSI_RequestCursorPositionReport"/>. ESC [ ? (y) ; (x) ; 1 R
     /// </summary>
-    public static readonly AnsiEscapeSequenceRequest CSI_RequestCursorPositionReport = new () { Request = CSI + "?6n", Terminator = "R" };
+    public static readonly AnsiEscapeSequence CSI_RequestCursorPositionReport = new () { Request = CSI + "?6n", Terminator = "R" };
 
     /// <summary>
     ///     The terminal reply to <see cref="CSI_RequestCursorPositionReport"/>. ESC [ ? (y) ; (x) R
@@ -1826,30 +1826,30 @@ public static class EscSeqUtils
     ///     The terminator indicating a reply to <see cref="CSI_SendDeviceAttributes"/> or
     ///     <see cref="CSI_SendDeviceAttributes2"/>
     /// </summary>
-    public static readonly AnsiEscapeSequenceRequest CSI_SendDeviceAttributes = new () { Request = CSI + "0c", Terminator = "c" };
+    public static readonly AnsiEscapeSequence CSI_SendDeviceAttributes = new () { Request = CSI + "0c", Terminator = "c" };
 
     /// <summary>
     ///     ESC [ > 0 c - Send Device Attributes (Secondary DA)
     ///     Windows Terminal v1.18+ emits: "\x1b[>0;10;1c" (vt100, firmware version 1.0, vt220)
     /// </summary>
-    public static readonly AnsiEscapeSequenceRequest CSI_SendDeviceAttributes2 = new () { Request = CSI + ">0c", Terminator = "c" };
+    public static readonly AnsiEscapeSequence CSI_SendDeviceAttributes2 = new () { Request = CSI + ">0c", Terminator = "c" };
 
     /// <summary>
     ///     CSI 16 t - Request sixel resolution (width and height in pixels)
     /// </summary>
-    public static readonly AnsiEscapeSequenceRequest CSI_RequestSixelResolution = new () { Request = CSI + "16t", Terminator = "t" };
+    public static readonly AnsiEscapeSequence CSI_RequestSixelResolution = new () { Request = CSI + "16t", Terminator = "t" };
 
     /// <summary>
     ///     CSI 14 t - Request window size in pixels (width x height)
     /// </summary>
-    public static readonly AnsiEscapeSequenceRequest CSI_RequestWindowSizeInPixels = new () { Request = CSI + "14t", Terminator = "t" };
+    public static readonly AnsiEscapeSequence CSI_RequestWindowSizeInPixels = new () { Request = CSI + "14t", Terminator = "t" };
 
     /// <summary>
     ///     CSI 1 8 t  | yes | yes |  yes  | report window size in chars
     ///     https://terminalguide.namepad.de/seq/csi_st-18/
     ///     The terminator indicating a reply to <see cref="CSI_ReportTerminalSizeInChars"/> : ESC [ 8 ; height ; width t
     /// </summary>
-    public static readonly AnsiEscapeSequenceRequest CSI_ReportTerminalSizeInChars = new () { Request = CSI + "18t", Terminator = "t", Value = "8" };
+    public static readonly AnsiEscapeSequence CSI_ReportTerminalSizeInChars = new () { Request = CSI + "18t", Terminator = "t", Value = "8" };
 
 
     /// <summary>

Terminal.Gui/Drawing/Sixel/SixelSupportDetector.cs

@@ -127,7 +127,7 @@ public class SixelSupportDetector
                       () => resultCallback (result));
     }
 
-    private static void QueueRequest (AnsiEscapeSequenceRequest req, Action<string> responseCallback, Action abandoned)
+    private static void QueueRequest (AnsiEscapeSequence req, Action<string> responseCallback, Action abandoned)
     {
         var newRequest = new AnsiEscapeSequenceRequest
         {

UICatalog/Scenarios/AnsiRequestsScenario.cs

@@ -104,7 +104,7 @@ public sealed class AnsiEscapeSequenceRequests : Scenario
                                               }
 
                                               var selAnsiEscapeSequenceRequestName = scrRequests [cbRequests.SelectedItem];
-                                              AnsiEscapeSequenceRequest selAnsiEscapeSequenceRequest = null;
+                                              AnsiEscapeSequence selAnsiEscapeSequenceRequest = null;
 
                                               switch (selAnsiEscapeSequenceRequestName)
                                               {
@@ -157,7 +157,7 @@ public sealed class AnsiEscapeSequenceRequests : Scenario
 
         btnResponse.Accepting += (s, e) =>
                                  {
-                                     var ansiEscapeSequenceRequest = new AnsiEscapeSequenceRequest
+                                     var ansiEscapeSequenceRequest = new AnsiEscapeSequence
                                      {
                                          Request = tfRequest.Text,
                                          Terminator = tfTerminator.Text,