Allow specifying default C# system impls by attribute

EcsactCsharpSystemImpl/Editor/CsharpSystemImplSettings.cs

@@ -0,0 +1,43 @@
+using UnityEditor;
+using UnityEngine;
+using System.IO;
+
+#nullable enable
+
+namespace Ecsact.Editor {
+
+public class CsharpSystemImplSettings : ScriptableObject {
+	private static CsharpSystemImplSettings? _instance;
+	public const string assetPath =
+		"Assets/Editor/EcsactCsharpSystemImplSettings.asset";
+
+	[Tooltip("The assembly that contains all the Ecsacts sytem impls")]
+	public UnityEditorInternal.AssemblyDefinitionAsset? systemImplsAssembly;
+
+	public static CsharpSystemImplSettings Get() {
+		if(_instance != null) {
+			return _instance;
+		}
+
+		_instance = AssetDatabase.LoadAssetAtPath<CsharpSystemImplSettings>(
+			assetPath
+		);
+		if(_instance == null) {
+			_instance = ScriptableObject.CreateInstance<CsharpSystemImplSettings>();
+			Directory.CreateDirectory(Path.GetDirectoryName(assetPath));
+			AssetDatabase.CreateAsset(_instance, assetPath);
+			AssetDatabase.SaveAssetIfDirty(_instance);
+		}
+
+		if(_instance == null) {
+			throw new global::System.Exception(
+				"Failed to load CsharpSystemImplSettings"
+			);
+		}
+
+		return _instance;
+	}
+
+}
+
+} // namespace Ecsact.Editor

EcsactCsharpSystemImpl/Editor/CsharpSystemImplSettingsEditor.cs

@@ -0,0 +1,231 @@
+using UnityEditor;
+using UnityEngine;
+using System.Linq;
+using System.Reflection;
+using System.Collections.Generic;
+using EcsactInternal;
+
+#nullable enable
+
+// https://docs.unity3d.com/Manual/AssemblyDefinitionFileFormat.html
+[System.Serializable]
+struct UnityAssemblyDefinitionFile {
+	public bool allowUnsafeCode;
+	public bool autoReferenced;
+	public bool noEngineReferences;
+	public List<string> defineConstraints;
+	public List<string> includePlatforms;
+	public List<string> excludePlatforms;
+	public string name;
+	public List<string> optionalUnityReferences;
+	public bool overrideReferences;
+	public List<string> precompiledReferences;
+	public List<string> references;
+}
+
+namespace Ecsact.Editor {
+
+[InitializeOnLoad]
+[CustomEditor(typeof(CsharpSystemImplSettings))]
+public class CsharpSystemImplSettingsEditor : UnityEditor.Editor {
+	const float maxWidthMethodDetails = 400f;
+	const float minWidthMethodDetails = 300f;
+	private static GUILayoutOption[] methodDetailsLayoutOptions = new[]{
+		GUILayout.MaxWidth(maxWidthMethodDetails),
+		GUILayout.MinWidth(minWidthMethodDetails),
+	};
+	private static List<global::System.Type>? systemLikeTypes;
+
+	static CsharpSystemImplSettingsEditor() {
+		EditorApplication.delayCall += () => {
+			InitializeDelayed();
+		};
+	}
+
+	private static void InitializeDelayed() {
+		var settings = CsharpSystemImplSettings.Get();
+		var runtimeSettings = EcsactRuntimeSettings.Get();
+		EnsureDefaultCsharpSystemImplsAssemblyName(settings, runtimeSettings);
+	}
+
+	private static void EnsureDefaultCsharpSystemImplsAssemblyName
+		( CsharpSystemImplSettings  settings
+		, EcsactRuntimeSettings     runtimeSettings
+		)
+	{
+		var newDefault = "";
+		if(settings.systemImplsAssembly != null) {
+			var asmDefJson = global::System.Text.Encoding.Default.GetString(
+				settings.systemImplsAssembly.bytes
+			);
+			var asmDef = JsonUtility.FromJson<UnityAssemblyDefinitionFile>(
+				asmDefJson
+			);
+
+			newDefault = asmDef.name;
+		} else {
+			newDefault = "";
+		}
+
+		if(runtimeSettings.defaultCsharpSystemImplsAssemblyName != newDefault) {
+			runtimeSettings.defaultCsharpSystemImplsAssemblyName = newDefault;
+			EditorUtility.SetDirty(runtimeSettings);
+		}
+	}
+
+	public override void OnInspectorGUI() {
+		var settings = (target as CsharpSystemImplSettings)!;
+
+		EditorGUI.BeginChangeCheck();
+		settings.systemImplsAssembly = EditorGUILayout.ObjectField(
+			obj: settings.systemImplsAssembly,
+			objType: typeof(UnityEditorInternal.AssemblyDefinitionAsset),
+			allowSceneObjects: false,
+			label: "Assembly"
+		) as UnityEditorInternal.AssemblyDefinitionAsset;
+
+		if(EditorGUI.EndChangeCheck()) {
+			EnsureDefaultCsharpSystemImplsAssemblyName(
+				settings,
+				EcsactRuntimeSettings.Get()
+			);
+		}
+
+		if(settings.systemImplsAssembly != null) {
+			var asmDefJson = global::System.Text.Encoding.Default.GetString(
+				settings.systemImplsAssembly.bytes
+			);
+			var asmDef = JsonUtility.FromJson<UnityAssemblyDefinitionFile>(
+				asmDefJson
+			);
+
+			if(!asmDef.noEngineReferences) {
+				EditorGUILayout.HelpBox(
+					$"The assembly definition {asmDef.name} has engine references " +
+					"enabled. Ecsact system implementations run on multiple threads " +
+					"and should not use engine apis that are not thread safe.",
+					MessageType.Warning,
+					wide: false
+				);
+			}
+
+			var assembly = Assembly.Load(asmDef.name);
+			if(assembly != null) {
+				var implDict = new Dictionary<int, List<MethodInfo>>();
+				foreach(var type in assembly.GetTypes()) {
+					foreach(var method in type.GetMethods()) {
+						var defaultSystemImplAttr =
+							method.GetCustomAttribute<Ecsact.DefaultSystemImplAttribute>();
+						if(defaultSystemImplAttr == null) continue;
+
+						var systemLikeId = defaultSystemImplAttr.systemLikeId;
+						if(!implDict.ContainsKey(systemLikeId)) {
+							implDict.Add(systemLikeId, new());
+						}
+
+						implDict[systemLikeId].Add(method);
+					}
+				}
+
+				if(systemLikeTypes == null) {
+					systemLikeTypes = Ecsact.Util.GetAllSystemLikeTypes().ToList();
+				}
+
+				if(implDict.Count == 0) {
+					EditorGUILayout.HelpBox(
+						$"No system implementations detected in assembly {asmDef.name}. " +
+						"Add the Ecsact.DefaultSystemImpl attribute to a public static " +
+						$"method found in the {asmDef.name} assembly.",
+						MessageType.Info,
+						wide: false
+					);
+				}
+
+				foreach(var systemLikeType in systemLikeTypes) {
+					var systemLikeId = Ecsact.Util.GetSystemID(systemLikeType);
+					var methods = implDict.GetValueOrDefault(systemLikeId, new());
+					DrawSystemImplDetail(systemLikeId, systemLikeType, methods);
+				}
+
+			} else {
+				EditorGUILayout.HelpBox(
+					$"Unable to load assembly definition by name: {asmDef.name}",
+					MessageType.Error,
+					wide: false
+				);
+			}
+		}
+	}
+
+	private string GetMethodFullName
+		( MethodInfo methodInfo
+		)
+	{
+		return methodInfo.DeclaringType.FullName + "." + methodInfo.Name;
+	}
+
+	private void DrawSystemImplMethodDetails
+		( MethodInfo methodInfo
+		)
+	{
+		EditorGUILayout.BeginHorizontal(methodDetailsLayoutOptions);
+
+		var style = new GUIStyle(EditorStyles.label);
+		style.richText = true;
+		var label = GetMethodFullName(methodInfo);
+		var errors = DefaultCsharpSystemImplsLoader.ValidateImplMethodInfo(
+			methodInfo
+		);
+
+		if(errors.Count > 0) {
+			label = $"<color=red>{label}</color>";
+		}
+
+		EditorGUILayout.LabelField(
+			label: new GUIContent(label, string.Join("\n", errors)),
+			options: new GUILayoutOption[]{},
+			style: style
+		);
+
+		EditorGUILayout.EndHorizontal();
+	}
+
+	private void DrawSystemImplDetail
+		( global::System.Int32  systemLikeId
+		, global::System.Type   systemLikeType
+		, List<MethodInfo>      methods
+		)
+	{
+		EditorGUILayout.BeginHorizontal();
+		EditorGUILayout.LabelField(
+			systemLikeType.FullName,
+			new GUILayoutOption[]{
+				GUILayout.ExpandWidth(true)
+			}
+		);
+
+		if(methods.Count == 0) {
+			EditorGUILayout.LabelField(
+				label: "(none)",
+				options: methodDetailsLayoutOptions
+			);
+			GUILayout.Space(10f);
+		} else if(methods.Count == 1) {
+			DrawSystemImplMethodDetails(methods[0]);
+		} else {
+			EditorGUILayout.BeginVertical(methodDetailsLayoutOptions);
+			foreach(var method in methods) {
+				DrawSystemImplMethodDetails(method);
+			}
+			EditorGUILayout.HelpBox(
+				"Multiple default system impls for the same system is not allowed.",
+				MessageType.Error,
+				wide: true
+			);
+			EditorGUILayout.EndVertical();
+		}
+		EditorGUILayout.EndHorizontal();
+	}
+}
+
+}

EcsactCsharpSystemImpl/Editor/EcsactCsharpSystemImplEditor.asmdef

@@ -0,0 +1,19 @@
+{
+    "name": "EcsactCsharpSystemImplEditor",
+    "rootNamespace": "",
+    "references": [
+        "GUID:2d10fa57d8150f7499b7579b289a41a2",
+        "GUID:6e7029456009ab94da19a8f93d5e3523"
+    ],
+    "includePlatforms": [
+        "Editor"
+    ],
+    "excludePlatforms": [],
+    "allowUnsafeCode": false,
+    "overrideReferences": false,
+    "precompiledReferences": [],
+    "autoReferenced": true,
+    "defineConstraints": [],
+    "versionDefines": [],
+    "noEngineReferences": false
+}