Performed a migration to the modern C# null/not-null checks

Author: Taritsyn

build/common.props

@@ -3,5 +3,6 @@
     <Copyright>Copyright © 2012-2024 Andrey Taritsyn</Copyright>
     <GenerateAssemblyTitleAttribute>false</GenerateAssemblyTitleAttribute>
     <GenerateAssemblyDescriptionAttribute>false</GenerateAssemblyDescriptionAttribute>
+    <LangVersion>14.0</LangVersion>
   </PropertyGroup>
 </Project>

src/MsieJavaScriptEngine/ActiveScript/ActiveScriptException.cs

@@ -163,7 +163,7 @@ public ActiveScriptException(string message, Exception innerException)
 		private ActiveScriptException(SerializationInfo info, StreamingContext context)
 			: base(info, context)
 		{
-			if (info != null)
+			if (info is not null)
 			{
 				_errorCode = info.GetInt32("ErrorCode");
 				_type = info.GetString("Type");
@@ -187,7 +187,7 @@ private ActiveScriptException(SerializationInfo info, StreamingContext context)
 		[SecurityPermission(SecurityAction.Demand, SerializationFormatter = true)]
 		public override void GetObjectData(SerializationInfo info, StreamingContext context)
 		{
-			if (info == null)
+			if (info is null)
 			{
 				throw new ArgumentNullException("info");
 			}

src/MsieJavaScriptEngine/ActiveScript/ActiveScriptJsEngineBase.ScriptSiteBase.cs

@@ -200,7 +200,7 @@ public void GetLcid(out int lcid)
 			public void GetItemInfo(string name, ScriptInfoFlags mask, ref IntPtr pUnkItem, ref IntPtr pTypeInfo)
 			{
 				object item = _jsEngine._hostItems[name];
-				if (item == null)
+				if (item is null)
 				{
 					throw new COMException(
 						string.Format(NetFrameworkStrings.Runtime_ItemNotFound, name),
@@ -254,7 +254,7 @@ public void OnScriptErrorDebug(IActiveScriptErrorDebug errorDebug, out bool ente
 				out bool callOnScriptErrorWhenContinuing)
 			{
 				var error = errorDebug as IActiveScriptError;
-				if (error != null)
+				if (error is not null)
 				{
 					ProcessActiveScriptError(error);
 				}
@@ -329,7 +329,7 @@ public CustomQueryInterfaceResult GetInterface(ref Guid iid, out IntPtr pInterfa
 					|| iid == typeof(IActiveScriptSiteDebug64).GUID
 					|| iid == typeof(IActiveScriptSiteDebugEx).GUID)
 				{
-					return _jsEngine._processDebugManagerWrapper != null ?
+					return _jsEngine._processDebugManagerWrapper is not null ?
 						CustomQueryInterfaceResult.NotHandled : CustomQueryInterfaceResult.Failed;
 				}
 

src/MsieJavaScriptEngine/ActiveScript/ActiveScriptJsEngineBase.cs

@@ -172,7 +172,7 @@ protected ActiveScriptJsEngineBase(JsEngineSettings settings, string clsid,
 			}
 			finally
 			{
-				if (_dispatch == null)
+				if (_dispatch is null)
 				{
 					Dispose();
 				}
@@ -187,14 +187,14 @@ protected ActiveScriptJsEngineBase(JsEngineSettings settings, string clsid,
 		/// or <c>0</c> to use the default maximum stack size specified in the header for the executable.</param>
 		private static void InitScriptDispatcher(int maxStackSize)
 		{
-			if (_dispatcher != null)
+			if (_dispatcher is not null)
 			{
 				return;
 			}
 
 			lock (_dispatcherSynchronizer)
 			{
-				if (_dispatcher != null)
+				if (_dispatcher is not null)
 				{
 					return;
 				}
@@ -328,7 +328,7 @@ private ActiveScriptException GetAndResetLastException()
 		private void ThrowError()
 		{
 			ActiveScriptException last = GetAndResetLastException();
-			if (last != null)
+			if (last is not null)
 			{
 				throw last;
 			}
@@ -539,7 +539,7 @@ private void InnerEmbedHostItem(string itemName, object value)
 			}
 			catch
 			{
-				if (oldValue != null)
+				if (oldValue is not null)
 				{
 					_hostItems[itemName] = oldValue;
 				}
@@ -607,12 +607,12 @@ private object[] MapToHostType(object[] args)
 		private static IExpando WrapScriptDispatch(object dispatch)
 		{
 			IExpando wrappedDispatch = null;
-			if (dispatch != null && dispatch.GetType().IsCOMObject)
+			if (dispatch is not null && dispatch.GetType().IsCOMObject)
 			{
 				wrappedDispatch = dispatch as IExpando;
 			}
 
-			if (wrappedDispatch == null)
+			if (wrappedDispatch is null)
 			{
 				throw new InvalidOperationException(
 					NetFrameworkStrings.Engine_ActiveScriptDispatcherNotInitialized);
@@ -652,7 +652,7 @@ private JsException WrapActiveScriptException(ActiveScriptException originalExce
 			wrapperException.Description = originalException.Description;
 
 			var wrapperScriptException = wrapperException as JsScriptException;
-			if (wrapperScriptException != null)
+			if (wrapperScriptException is not null)
 			{
 				wrapperScriptException.Type = originalException.Type;
 				wrapperScriptException.DocumentName = originalException.DocumentName;
@@ -798,7 +798,7 @@ public override bool HasVariable(string variableName)
 				try
 				{
 					object variableValue = InnerGetVariableValue(variableName);
-					variableExist = variableValue != null;
+					variableExist = variableValue is not null;
 				}
 				catch (ActiveScriptException e)
 				{
@@ -933,7 +933,7 @@ public override void Dispose()
 		{
 			if (_disposedFlag.Set())
 			{
-				if (_debuggingStarted && _debugDocuments != null)
+				if (_debuggingStarted && _debugDocuments is not null)
 				{
 					foreach (UIntPtr debugDocumentKey in _debugDocuments.Keys)
 					{
@@ -945,11 +945,11 @@ public override void Dispose()
 					_debugDocuments = null;
 				}
 
-				if (_processDebugManagerWrapper != null)
+				if (_processDebugManagerWrapper is not null)
 				{
 					_processDebugManagerWrapper.RemoveApplication(_debugApplicationCookie);
 
-					if (_debugApplicationWrapper != null)
+					if (_debugApplicationWrapper is not null)
 					{
 						_debugApplicationWrapper.Close();
 						_debugApplicationWrapper = null;
@@ -958,28 +958,28 @@ public override void Dispose()
 					_processDebugManagerWrapper = null;
 				}
 
-				if (_documentNames != null)
+				if (_documentNames is not null)
 				{
 					_documentNames.Clear();
 					_documentNames = null;
 				}
 
 				_dispatcher.Invoke(() =>
 				{
-					if (_dispatch != null)
+					if (_dispatch is not null)
 					{
 						Marshal.ReleaseComObject(_dispatch);
 						_dispatch = null;
 					}
 
-					if (_activeScriptWrapper != null)
+					if (_activeScriptWrapper is not null)
 					{
 						_activeScriptWrapper.Dispose();
 						_activeScriptWrapper = null;
 					}
 				});
 
-				if (_hostItems != null)
+				if (_hostItems is not null)
 				{
 					_hostItems.Clear();
 					_hostItems = null;

src/MsieJavaScriptEngine/ActiveScript/ActiveScriptJsErrorHelpers.cs

@@ -71,12 +71,12 @@ public static string GetErrorTypeByNumber(int errorNumber, Dictionary<int, strin
 		/// <returns>Short name of error item</returns>
 		public static string ShortenErrorItemName(string itemName, string prefix)
 		{
-			if (itemName == null)
+			if (itemName is null)
 			{
 				throw new ArgumentNullException(nameof(itemName));
 			}
 
-			if (prefix == null)
+			if (prefix is null)
 			{
 				throw new ArgumentNullException(nameof(prefix));
 			}

src/MsieJavaScriptEngine/ActiveScript/ActiveScriptWrapper32.cs

@@ -116,7 +116,7 @@ public override object ParseScriptText(string code, string itemName, object cont
 
 		public override void EnumStackFrames(out IEnumDebugStackFrames enumFrames)
 		{
-			if (_debugStackFrameSniffer32 != null)
+			if (_debugStackFrameSniffer32 is not null)
 			{
 				_debugStackFrameSniffer32.EnumStackFrames(out enumFrames);
 			}

src/MsieJavaScriptEngine/ActiveScript/ActiveScriptWrapper64.cs

@@ -116,7 +116,7 @@ public override object ParseScriptText(string code, string itemName, object cont
 
 		public override void EnumStackFrames(out IEnumDebugStackFrames enumFrames)
 		{
-			if (_debugStackFrameSniffer64 != null)
+			if (_debugStackFrameSniffer64 is not null)
 			{
 				_debugStackFrameSniffer64.EnumStackFrames(out enumFrames);
 			}

src/MsieJavaScriptEngine/ActiveScript/ActiveScriptWrapperBase.cs

@@ -69,7 +69,7 @@ protected ActiveScriptWrapperBase(string clsid, ScriptLanguageVersion languageVe
 			if (languageVersion != ScriptLanguageVersion.None)
 			{
 				var activeScriptProperty = _activeScript as IActiveScriptProperty;
-				if (activeScriptProperty != null)
+				if (activeScriptProperty is not null)
 				{
 					object scriptLanguageVersion = (int)languageVersion;
 					uint result = activeScriptProperty.SetProperty((uint)ScriptProperty.InvokeVersioning,
@@ -222,7 +222,7 @@ public void InterruptScriptThread(uint scriptThreadId, ref EXCEPINFO exceptionIn
 		/// <param name="type">The type of garbage collection</param>
 		public void CollectGarbage(ScriptGCType type)
 		{
-			if (_activeScriptGarbageCollector != null)
+			if (_activeScriptGarbageCollector is not null)
 			{
 				_activeScriptGarbageCollector.CollectGarbage(type);
 			}
@@ -247,7 +247,7 @@ protected virtual void Dispose(bool disposing)
 			{
 				_activeScriptGarbageCollector = null;
 
-				if (_activeScript != null)
+				if (_activeScript is not null)
 				{
 					_activeScript.Close();
 					Marshal.FinalReleaseComObject(_activeScript);

src/MsieJavaScriptEngine/ActiveScript/ClassicActiveScriptJsEngine.ScriptSite.cs

@@ -95,7 +95,7 @@ protected override CallStackItem[] GetCallStackItems()
 						uint lineNumber = 0;
 						uint columnNumber = 0;
 
-						if (documentContext != null)
+						if (documentContext is not null)
 						{
 							IDebugDocument document;
 							documentContext.GetDocument(out document);

src/MsieJavaScriptEngine/ActiveScript/Debugging/DebugDocument.cs

@@ -120,14 +120,14 @@ private void Initialize()
 		/// </summary>
 		public void Close()
 		{
-			if (_node != null)
+			if (_node is not null)
 			{
 				_node.Detach();
 				_node.Close();
 				_node = null;
 			}
 
-			if (_lines != null)
+			if (_lines is not null)
 			{
 				_lines.Clear();
 			}