Adding an attribute to a class after the documentation comment trivia

Question

I am trying to turn

namespace DevComponents.WpfEditors.Primitives
{
 /// <summary>
 /// Interaction logic for EditorFreeTextButton.xaml
 /// </summary>
 public partial class EditorFreeTextButton : EditorButton
 {
 public EditorFreeTextButton()
 {
 InitializeComponent();
 }
 }
}

into

namespace DevComponents.WpfEditors.Primitives
{
 /// <summary>
 /// Interaction logic for EditorFreeTextButton.xaml
 /// </summary>
 [System.Reflection.Obfuscation(Exclude = true)]
 public partial class EditorFreeTextButton : EditorButton
 {
 public EditorFreeTextButton()
 {
 InitializeComponent();
 }
 }
}

through Roslyn. I have the following code that works

private static SyntaxNode AddAnnotation(ClassDeclarationSyntax classNode, SyntaxNode rootNode)
{
 var name = SyntaxFactory.ParseName("System.Reflection.Obfuscation");
 var arguments = SyntaxFactory.ParseAttributeArgumentList("(Exclude = true)");
 var attribute = SyntaxFactory.Attribute(name, arguments);
 var leadingTrivia = classNode.GetLeadingTrivia();
 var whitespace = leadingTrivia.LastOrDefault(x => x.Kind() == SyntaxKind.WhitespaceTrivia);
 var attributeList = SyntaxFactory.AttributeList(SyntaxFactory.SingletonSeparatedList(attribute))
 .WithTrailingTrivia(SyntaxFactory.CarriageReturnLineFeed);
 var newClassNode = classNode.WithoutLeadingTrivia()
 .WithLeadingTrivia(whitespace)
 .AddAttributeLists(attributeList)
 .WithLeadingTrivia(leadingTrivia);
 rootNode = rootNode.ReplaceNode(classNode, newClassNode);
 return rootNode;
}

However I feel like I am coding in circles to get all the leading Trivia right.

Is there a easier way to insert an attribute to be after the SingleLineDocumentationCommentTrivia and be formatted correctly with the correct leading whitespace trivia?

• Scott Chamberlain: @Hosch250 I think i misread what you said before I commented and you did not use the function I think you where using. Please undelete your answer so I can look in to and ask you about Formatter.Annotation more.
• user34073: I'm so sorry, I missed your notification.

Answer 1

Look into the WithAnnotation(Formatter.Annotation) member. This should create a new node with the correct leading indentation.

var newClassNode = classNode.AddAttributeLists(attributeList)
 .WithAnnotation(Formatter.Annotation)

• Scott Chamberlain: That puts the annotation before the SingleLineDocumentationCommentTrivia. however the Formatter.Annotation might be useful
• user34073: OK, I'll delete this then.