feat: add CancellationSource class attribute

Godot 4 Tests/Run.cs

@@ -21,6 +21,7 @@ private static IEnumerable<Func<ITest>> Tests
             yield return ITest.GetTest<AutoloadExtensionTests>;
             yield return ITest.GetTest<BuiltInScriptTest>;
             yield return ITest.GetTest<CachedNodes>;
+            yield return ITest.GetTest<CancellationSourceTests>;
             yield return ITest.GetTest<DiscardWorkaroundTest>;
             yield return ITest.GetTest<EditableChildrenTest>;
             yield return ITest.GetTest<EditableChildrenWithTraversalTest>;

Godot 4 Tests/TestScenes/CancellationSource/CancellationSourceTests.cs

@@ -0,0 +1,38 @@
+using System.Threading;
+using FluentAssertions;
+using Godot;
+using GodotSharp.BuildingBlocks.TestRunner;
+
+namespace GodotTests.TestScenes;
+
+[SceneTree]
+[CancellationSource]
+public partial class CancellationSourceTests : Node, ITest
+{
+    private CancellationToken capturedToken;
+
+    void ITest.InitTests()
+    {
+        Cts.Should().BeNull();
+    }
+
+    void ITest.EnterTests()
+    {
+        // After entering tree, CTS should be created
+        Cts.Should().NotBeNull();
+        Cts.Token.IsCancellationRequested.Should().BeFalse();
+        Cts.Token.CanBeCanceled.Should().BeTrue();
+
+        // Capture token to verify it gets cancelled on exit
+        capturedToken = Cts.Token;
+    }
+
+    void ITest.ExitTests()
+    {
+        // After exiting tree, the captured token should be cancelled
+        capturedToken.IsCancellationRequested.Should().BeTrue();
+
+        // The property should now return null
+        Cts.Should().BeNull();
+    }
+}

Godot 4 Tests/TestScenes/CancellationSource/CancellationSourceTests.cs.uid

@@ -0,0 +1 @@
+uid://docd60525k7es

Godot 4 Tests/TestScenes/CancellationSource/CancellationSourceTests.tscn

@@ -0,0 +1,6 @@
+[gd_scene format=3]
+
+[ext_resource type="Script" path="res://TestScenes/Feature.CancellationSource/CancellationSourceTests.cs" id="1"]
+
+[node name="Root" type="Node"]
+script = ExtResource("1")

NRT.Tests/GD4.NRT/TestCancellationSource.cs

@@ -0,0 +1,6 @@
+using Godot;
+
+namespace NRT.Tests;
+
+[CancellationSource]
+public partial class TestCancellationSource : Node;

README.md

@@ -25,6 +25,10 @@ C# Source Generators for use with the Godot Game Engine
 * [NEW] `AutoEnum` enum/class attribute (GD4 only):
   * (enum) Generates efficient Str/Parse for enums
   * (class) Generates enum for static data classes (for editor/network use)
+* [NEW] `CancellationSource` class attribute (GD4 only):
+  * Generates a `CancellationTokenSource` property (`Cts`) on a Node
+  * Automatically creates a new source on tree enter, cancels and disposes on tree exit
+  * Handles re-entry (fresh source each time the node enters the tree)
 * `Autoload` class attribute:
   * Provide strongly typed access to autoload nodes defined in godot.project
 * `CodeComments` class attribute:
@@ -80,6 +84,7 @@ C# Source Generators for use with the Godot Game Engine
     - [`AnimNames`](#animnames)
     - [`AudioBus`](#audiobus)
     - [`AutoEnum`](#autoenum)
+    - [`CancellationSource`](#cancellationsource)
     - [`Autoload`](#autoload)
     - [`CodeComments`](#codecomments)
     - [`GlobalGroups`](#globalgroups)
@@ -405,6 +410,74 @@ var s = MapData.Outside.ToStr(); // s = "Outside"
 var d = MapData.FromStr(s);      // d = MapData.Outside
 ```
 
+### `CancellationSource`
+  * Class attribute (GD4 only)
+  * Generates a `CancellationTokenSource` property (`Cts`) on a Node
+  * Automatically creates a new source when the node enters the tree
+  * Cancels and disposes the source when the node exits the tree
+  * Handles re-entry (fresh source each time)
+  * Uses lazy initialization to avoid constructor conflicts
+#### Examples:
+```cs
+[CancellationSource]
+public partial class MyNode : Node
+{
+    public override void _Ready()
+    {
+        DoWork(Cts.Token);
+    }
+
+    private async void DoWork(CancellationToken token)
+    {
+        while (!token.IsCancellationRequested)
+        {
+            await DoSomethingAsync(token);
+        }
+    }
+}
+```
+Generates:
+```cs
+partial class MyNode
+{
+    private CancellationTokenSource __cancellationTokenSource;
+    private bool __cancellationSourceInitialized;
+
+    public CancellationTokenSource Cts
+    {
+        get
+        {
+            __InitCancellationSource();
+            return __cancellationTokenSource;
+        }
+    }
+
+    private void __InitCancellationSource()
+    {
+        if (__cancellationSourceInitialized) return;
+        __cancellationSourceInitialized = true;
+
+        if (IsInsideTree())
+            __cancellationTokenSource = new CancellationTokenSource();
+
+        TreeEntered += __CancellationSource_OnTreeEntered;
+        TreeExiting += __CancellationSource_OnTreeExiting;
+    }
+
+    private void __CancellationSource_OnTreeEntered()
+    {
+        __cancellationTokenSource = new CancellationTokenSource();
+    }
+
+    private void __CancellationSource_OnTreeExiting()
+    {
+        __cancellationTokenSource?.Cancel();
+        __cancellationTokenSource?.Dispose();
+        __cancellationTokenSource = null;
+    }
+}
+```
+
 ### `Autoload`
   * `Autoload` class attribute
     * Provides strongly typed access to autoload nodes defined in editor project settings

SourceGenerators/CancellationSourceExtensions/CancellationSourceAttribute.cs

@@ -0,0 +1,4 @@
+namespace Godot;
+
+[AttributeUsage(AttributeTargets.Class)]
+public sealed class CancellationSourceAttribute : Attribute;

SourceGenerators/CancellationSourceExtensions/CancellationSourceDataModel.cs

@@ -0,0 +1,11 @@
+using Microsoft.CodeAnalysis;
+
+namespace GodotSharp.SourceGenerators.CancellationSourceExtensions;
+
+internal class CancellationSourceDataModel(INamedTypeSymbol symbol) : ClassDataModel(symbol)
+{
+    protected override string Str()
+    {
+        return $"ClassName: {ClassName}";
+    }
+}

SourceGenerators/CancellationSourceExtensions/CancellationSourceSourceGenerator.cs

@@ -0,0 +1,22 @@
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Scriban;
+
+namespace GodotSharp.SourceGenerators.CancellationSourceExtensions;
+
+[Generator]
+internal class CancellationSourceSourceGenerator : SourceGeneratorForDeclaredTypeWithAttribute<Godot.CancellationSourceAttribute>
+{
+    private static Template CancellationSourceTemplate => field ??= Template.Parse(Resources.CancellationSourceTemplate);
+
+    protected override (string GeneratedCode, DiagnosticDetail Error) GenerateCode(Compilation compilation, SyntaxNode node, INamedTypeSymbol symbol, AttributeData attribute, AnalyzerConfigOptions options)
+    {
+        var model = new CancellationSourceDataModel(symbol);
+        Log.Debug($"--- MODEL ---\n{model}\n");
+
+        var output = CancellationSourceTemplate.Render(model, Shared.Utils);
+        Log.Debug($"--- OUTPUT ---\n{output}<END>\n");
+
+        return (output, null);
+    }
+}

SourceGenerators/CancellationSourceExtensions/CancellationSourceTemplate.scriban

@@ -0,0 +1,49 @@
+{{-#####-CONTENT-#####-}}
+
+{{~ capture body ~}}
+    [{{EditorBrowsableNever}}]
+    private System.Threading.CancellationTokenSource __cancellationTokenSource;
+
+    [{{EditorBrowsableNever}}]
+    private bool __cancellationSourceInitialized;
+
+    public System.Threading.CancellationTokenSource Cts
+    {
+        get
+        {
+            __InitCancellationSource();
+            return __cancellationTokenSource;
+        }
+    }
+
+    [{{EditorBrowsableNever}}]
+    private void __InitCancellationSource()
+    {
+        if (__cancellationSourceInitialized) return;
+        __cancellationSourceInitialized = true;
+
+        if (IsInsideTree())
+            __cancellationTokenSource = new System.Threading.CancellationTokenSource();
+
+        TreeEntered += __CancellationSource_OnTreeEntered;
+        TreeExiting += __CancellationSource_OnTreeExiting;
+    }
+
+    [{{EditorBrowsableNever}}]
+    private void __CancellationSource_OnTreeEntered()
+    {
+        __cancellationTokenSource = new System.Threading.CancellationTokenSource();
+    }
+
+    [{{EditorBrowsableNever}}]
+    private void __CancellationSource_OnTreeExiting()
+    {
+        __cancellationTokenSource?.Cancel();
+        __cancellationTokenSource?.Dispose();
+        __cancellationTokenSource = null;
+    }
+{{~ end ~}}
+
+{{-#####-MAIN-#####-}}
+
+{{~ RenderClass body ~}}

SourceGenerators/CancellationSourceExtensions/Resources.cs

@@ -0,0 +1,9 @@
+using System.Reflection;
+
+namespace GodotSharp.SourceGenerators.CancellationSourceExtensions;
+
+internal static class Resources
+{
+    private const string cancellationSourceTemplate = "GodotSharp.SourceGenerators.CancellationSourceExtensions.CancellationSourceTemplate.scriban";
+    public static readonly string CancellationSourceTemplate = Assembly.GetExecutingAssembly().GetEmbeddedResource(cancellationSourceTemplate);
+}