feat: backport API to Unity 2021 for compatibility

Editor/Editors/YarnProjectImporterEditor.cs

@@ -234,7 +234,7 @@ protected override void Apply()
                 localisationFieldsContainer?.Add(newBaseLanguageField);
             }
         }
-
+        #if UNITY_2022_2_OR_NEWER
         public override void DiscardChanges()
         {
             localizationEntryFields.Clear();
@@ -250,7 +250,23 @@ public override void DiscardChanges()
 
             inspectorRoot?.Add(CreateInspectorGUI());
         }
+        #else
+        protected override void ResetValues()
+        {
+            localizationEntryFields.Clear();
+            sourceEntryFields.Clear();
+            LocalisationsAddedOrRemoved = false;
+            BaseLanguageNameModified = false;
+            SourceFilesAddedOrRemoved = false;
 
+            base.ResetValues();
+
+            var inspectorRoot = uiRoot?.parent;
+            uiRoot?.RemoveFromHierarchy();
+
+            inspectorRoot?.Add(CreateInspectorGUI());
+        }
+        #endif
         public override VisualElement CreateInspectorGUI()
         {
             if (!(target is YarnProjectImporter yarnProjectImporter))

Editor/Utility/EnsureInputModuleAvailableEditor.cs

@@ -0,0 +1,39 @@
+#nullable enable
+using UnityEditor;
+using UnityEngine;
+
+namespace Yarn.Unity.Editor
+{
+    [CustomEditor(typeof(EnsureInputModuleAvailable))]
+    public class EnsureInputModuleAvailableEditor : UnityEditor.Editor
+    {
+        public override void OnInspectorGUI()
+        {
+            const string message = "This component checks to see if a UI Input Module exists in the scene. If one isn't available, it creates an input module on this object that's compatible with your current input system.";
+
+            EditorGUILayout.HelpBox(message, MessageType.Info);
+
+            if (target is not EnsureInputModuleAvailable module)
+            {
+                return;
+            }
+
+            if (module.TryGetComponent<UnityEngine.EventSystems.BaseInputModule>(out var existingInputModule))
+            {
+                if ((existingInputModule.hideFlags & HideFlags.DontSaveInEditor) != 0)
+                {
+                    EditorGUILayout.Space();
+
+                    EditorGUILayout.HelpBox("The " + existingInputModule.GetType().Name + " on this object is marked as temporary, and won't be saved in the scene. Click the button below if you'd like to include it in the saved scene.", MessageType.Info);
+                    if (GUILayout.Button("Save in Scene"))
+                    {
+                        existingInputModule.hideFlags &= ~HideFlags.DontSaveInEditor;
+                        UnityEditor.EditorUtility.SetDirty(existingInputModule.gameObject);
+                        var scene = existingInputModule.gameObject.scene;
+                        UnityEditor.SceneManagement.EditorSceneManager.SaveScene(scene);
+                    }
+                }
+            }
+        }
+    }
+}

Runtime/DialogueRunner/DialogueRunner.cs

@@ -957,7 +957,8 @@ public void StartDialogue(string nodeName)
 
             dialogueCompletionSource = new YarnTaskCompletionSource();
 
-            dialogueCancellationSource = CancellationTokenSource.CreateLinkedTokenSource(this.destroyCancellationToken);
+            dialogueCancellationSource = CancellationTokenSource.CreateLinkedTokenSource(this.GetDestroyCancellationToken());
+
             LineProvider.YarnProject = yarnProject;
 
             EnsureCommandDispatcherReady();

Runtime/Utility/ApplicationExitCompat.cs

@@ -0,0 +1,40 @@
+using System.Threading;
+using UnityEditor;
+using UnityEngine;
+
+namespace Yarn.Unity
+{
+    public static class ApplicationExitCompat
+    {
+        private static CancellationTokenSource _exitCts;
+
+        public static CancellationToken ExitCancellationToken
+        {
+            get
+            {
+                _exitCts ??= new CancellationTokenSource();
+
+                return _exitCts.Token;
+            }
+        }
+
+        [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)]
+        private static void Init()
+        {
+            _exitCts ??= new CancellationTokenSource();
+
+            #if UNITY_EDITOR
+            EditorApplication.playModeStateChanged += state =>
+            {
+                if (state == PlayModeStateChange.ExitingPlayMode)
+                {
+                    _exitCts.Cancel();
+                }
+            };
+            #endif
+
+            Application.quitting += () => { _exitCts.Cancel(); };
+        }
+    }
+
+}

Runtime/Utility/EnsureInputModuleAvailable.cs

@@ -95,44 +95,4 @@ private bool IsInputModuleInScene
             }
         }
     }
-
-#if UNITY_EDITOR
-    namespace Editor
-    {
-        using UnityEditor;
-        [CustomEditor(typeof(EnsureInputModuleAvailable))]
-        public class EnsureInputModuleAvailableEditor : UnityEditor.Editor
-        {
-            public override void OnInspectorGUI()
-            {
-                const string message = "This component checks to see if a UI Input Module exists in the scene. If one isn't available, it creates an input module on this object that's compatible with your current input system.";
-
-                EditorGUILayout.HelpBox(message, MessageType.Info);
-
-                if (target is not EnsureInputModuleAvailable module)
-                {
-                    return;
-                }
-
-                if (module.TryGetComponent<UnityEngine.EventSystems.BaseInputModule>(out var existingInputModule))
-                {
-                    if ((existingInputModule.hideFlags & HideFlags.DontSaveInEditor) != 0)
-                    {
-                        EditorGUILayout.Space();
-
-                        EditorGUILayout.HelpBox("The " + existingInputModule.GetType().Name + " on this object is marked as temporary, and won't be saved in the scene. Click the button below if you'd like to include it in the saved scene.", MessageType.Info);
-                        if (GUILayout.Button("Save in Scene"))
-                        {
-                            existingInputModule.hideFlags &= ~HideFlags.DontSaveInEditor;
-                            UnityEditor.EditorUtility.SetDirty(existingInputModule.gameObject);
-                            var scene = existingInputModule.gameObject.scene;
-                            UnityEditor.SceneManagement.EditorSceneManager.SaveScene(scene);
-                        }
-                    }
-                }
-            }
-        }
-    }
-#endif
-
 }

Runtime/Utility/MonoBehaviourExtensions.cs

@@ -0,0 +1,35 @@
+#nullable enable
+using System.Threading;
+using UnityEngine;
+
+namespace Yarn.Unity
+{
+    public static class MonoBehaviourExtensions
+    {
+        /// <summary>
+        /// Gets a CancellationToken that is cancelled when the MonoBehaviour's GameObject is destroyed.
+        /// </summary>
+        public static CancellationToken GetDestroyCancellationToken(this MonoBehaviour mb)
+        {
+            #if UNITY_2022_2_OR_NEWER
+            return mb.destroyCancellationToken;
+            #endif
+
+            DestroyTokenNotifier notifier = mb.gameObject.GetComponent<DestroyTokenNotifier>()
+                                            ?? mb.gameObject.AddComponent<DestroyTokenNotifier>();
+
+            return notifier.Cts.Token;
+        }
+    }
+
+    internal class DestroyTokenNotifier : MonoBehaviour
+    {
+        public CancellationTokenSource Cts { get; } = new();
+
+        private void OnDestroy()
+        {
+            Cts.Cancel();
+            Cts.Dispose();
+        }
+    }
+}

Runtime/Views/Legacy/DialogueViewBase.cs

@@ -383,7 +383,7 @@ public override async YarnTask RunLineAsync(LocalizedLine line, LineCancellation
             // 2. The line is cancelled.
             while (phaseComplete == false
                    && token.IsNextLineRequested == false
-                   && Application.exitCancellationToken.IsCancellationRequested == false)
+                   && GetExitCancellationToken().IsCancellationRequested == false)
             {
                 await YarnTask.Yield();
             }
@@ -396,7 +396,7 @@ public override async YarnTask RunLineAsync(LocalizedLine line, LineCancellation
                 phaseComplete = false;
                 this.InterruptLine(line, PhaseComplete);
                 while (phaseComplete == false
-                  && Application.exitCancellationToken.IsCancellationRequested == false)
+                  && GetExitCancellationToken().IsCancellationRequested == false)
                 {
                     await YarnTask.Yield();
                 }
@@ -408,7 +408,7 @@ public override async YarnTask RunLineAsync(LocalizedLine line, LineCancellation
             this.DismissLine(PhaseComplete);
 
             while (phaseComplete == false
-                  && Application.exitCancellationToken.IsCancellationRequested == false)
+                  && GetExitCancellationToken().IsCancellationRequested == false)
             {
                 await YarnTask.Yield();
             }
@@ -428,12 +428,12 @@ public override async YarnTask RunLineAsync(LocalizedLine line, LineCancellation
                 selectedOptionID = selectedID;
             });
 
-            while (selectedOptionID == -1 && cancellationToken.IsCancellationRequested == false && Application.exitCancellationToken.IsCancellationRequested == false)
+            while (selectedOptionID == -1 && cancellationToken.IsCancellationRequested == false && GetExitCancellationToken().IsCancellationRequested == false)
             {
                 await YarnTask.Yield();
             }
 
-            if (cancellationToken.IsCancellationRequested || Application.exitCancellationToken.IsCancellationRequested)
+            if (cancellationToken.IsCancellationRequested || GetExitCancellationToken().IsCancellationRequested)
             {
                 // We were cancelled or are exiting the game. Return null.
                 return null;
@@ -453,5 +453,13 @@ public override async YarnTask RunLineAsync(LocalizedLine line, LineCancellation
             // an option that was valid. Throw an error.
             throw new InvalidOperationException($"Option view selected an invalid option ID ({selectedOptionID})");
         }
+
+        private static CancellationToken GetExitCancellationToken()
+        {
+            #if UNITY_2022_2_OR_NEWER
+            return Application.exitCancellationToken;
+            #endif
+            return ApplicationExitCompat.ExitCancellationToken;
+        }
     }
 }