 }
 
 
-extension NSAttributedString.Key {
+private extension NSAttributedString.Key {
     
     static let syntaxType = NSAttributedString.Key("CotEditor.SyntaxType")
 }

        
        // use cache if the content of the whole document is the same as the last
        if let cache = self.highlightCache, cache.styleName == self.style.name, cache.string == self.textStorage.string {
            self.apply(highlights: cache.highlights, range: wholeRange)
            completionHandler()
            return nil
        }

        
        // just clear current highlight and return if no coloring needs
        guard self.style.hasHighlightDefinition else {
            self.textStorage.apply(highlights: [:], range: highlightRange)
            completionHandler()
            return nil
        }
