reduce duplicate IndexOf calls

src/Controls/src/Core/HandlerImpl/Application/Application.Impl.cs

@@ -76,7 +76,7 @@ internal void RemoveWindow(Window window)
 			if (window is Element windowElement)
 			{
 				var oldIndex = InternalChildren.IndexOf(windowElement);
-				InternalChildren.Remove(windowElement);
+				InternalChildren.RemoveAt(oldIndex);
 				windowElement.Parent = null;
 				OnChildRemoved(windowElement, oldIndex);
 			}

src/Controls/src/Core/ListView.cs

@@ -456,10 +456,12 @@ protected override void UnhookContent(Cell content)
 		{
 			base.UnhookContent(content);
 
-			if (content == null || !_logicalChildren.Contains(content))
+			if (content == null)
 				return;
 			var index = _logicalChildren.IndexOf(content);
-			_logicalChildren.Remove(content);
+			if (index == -1)
+				return;
+			_logicalChildren.RemoveAt(index);
 			content.Parent = null;
 			VisualDiagnostics.OnChildRemoved(this, content, index);
 

src/Controls/src/Core/Shell/Shell.cs

@@ -713,11 +713,11 @@ public void RemoveLogicalChild(Element element)
 
 			element.Parent = null;
 
-			if (!_logicalChildren.Contains(element))
+			var oldLogicalIndex = _logicalChildren.IndexOf(element);
+			if (oldLogicalIndex == -1)
 				return;
 
-			var oldLogicalIndex = _logicalChildren.IndexOf(element);
-			_logicalChildren.Remove(element);
+			_logicalChildren.RemoveAt(oldLogicalIndex);
 			OnChildRemoved(element, oldLogicalIndex);
 			VisualDiagnostics.OnChildRemoved(this, element, oldLogicalIndex);
 		}

src/Controls/src/Core/VisualElement.cs

@@ -178,10 +178,12 @@ static void OnTransformChanged(BindableObject bindable, object oldValue, object
 			var transforms = ((string)newValue).Split(' ');
 			foreach (var transform in transforms)
 			{
-				if (string.IsNullOrEmpty(transform) || transform.IndexOf("(", StringComparison.Ordinal) < 0 || transform.IndexOf(")", StringComparison.Ordinal) < 0)
+				var openBracket = transform.IndexOf("(", StringComparison.Ordinal);
+				var closeBracket = transform.IndexOf(")", StringComparison.Ordinal);
+				if (string.IsNullOrEmpty(transform) || openBracket < 0 || closeBracket < 0)
 					throw new FormatException("Format for transform is 'none | transform(value) [transform(value) ]*'");
-				var transformName = transform.Substring(0, transform.IndexOf("(", StringComparison.Ordinal));
-				var value = transform.Substring(transform.IndexOf("(", StringComparison.Ordinal) + 1, transform.IndexOf(")", StringComparison.Ordinal) - transform.IndexOf("(", StringComparison.Ordinal) - 1);
+				var transformName = transform.Substring(0, openBracket);
+				var value = transform.Substring(openBracket + 1, closeBracket - openBracket - 1);
 				double translationX, translationY, scaleX, scaleY, rotateX, rotateY, rotate;
 				if (transformName.StartsWith("translateX", StringComparison.OrdinalIgnoreCase) && double.TryParse(value, out translationX))
 					bindable.SetValue(TranslationXProperty, translationX);

src/Controls/src/Xaml/TypeArgumentsParser.cs

@@ -45,9 +45,10 @@ static XmlType Parse(string match, ref string remaining, IXmlNamespaceResolver r
 			IList<XmlType> typeArguments = null;
 			if (isGeneric)
 			{
+				var openBracket = type.IndexOf("(", StringComparison.Ordinal);
 				typeArguments = ParseExpression(
-					type.Substring(type.IndexOf("(", StringComparison.Ordinal) + 1, type.LastIndexOf(")", StringComparison.Ordinal) - type.IndexOf("(", StringComparison.Ordinal) - 1), resolver, lineinfo);
-				type = type.Substring(0, type.IndexOf("(", StringComparison.Ordinal));
+					type.Substring(openBracket + 1, type.LastIndexOf(")", StringComparison.Ordinal) - openBracket - 1), resolver, lineinfo);
+				type = type.Substring(0, openBracket);
 			}
 
 			var split = type.Split(':');

src/Controls/src/Xaml/XmlTypeXamlExtensions.cs

@@ -68,8 +68,9 @@ static class XmlTypeXamlExtensions
 			for (var i = 0; i < lookupNames.Count; i++)
 			{
 				var name = lookupNames[i];
-				if (name.IndexOf(":", StringComparison.Ordinal) != -1)
-					name = name.Substring(name.LastIndexOf(':') + 1);
+				var lastIndex = name.LastIndexOf(":", StringComparison.Ordinal);
+				if (lastIndex != -1)
+					name = name.Substring(lastIndex + 1);
 				if (typeArguments != null)
 					name += "`" + typeArguments.Count; //this will return an open generic Type
 				lookupNames[i] = name;

src/Core/src/Handlers/View/ViewHandlerOfT.Windows.cs

@@ -20,9 +20,9 @@ protected override void SetupContainer()
 				return;
 
 			var oldParent = (Panel?)PlatformView.Parent;
-
 			var oldIndex = oldParent?.Children.IndexOf(PlatformView);
-			oldParent?.Children.Remove(PlatformView);
+			if (oldIndex is int oldIdx && oldIdx >= 0)
+				oldParent?.Children.RemoveAt(oldIdx);
 
 			ContainerView ??= new WrapperView();
 			((WrapperView)ContainerView).Child = PlatformView;
@@ -43,9 +43,9 @@ protected override void RemoveContainer()
 			}
 
 			var oldParent = (Panel?)ContainerView.Parent;
-
 			var oldIndex = oldParent?.Children.IndexOf(ContainerView);
-			oldParent?.Children.Remove(ContainerView);
+			if (oldIndex is int oldIdx && oldIdx >= 0)
+				oldParent?.Children.RemoveAt(oldIdx);
 
 			CleanupContainerView(ContainerView);
 			ContainerView = null;