Highlight JS keywords

MongoView/Synax Highlighting/JavaScriptHighlighter.swift

@@ -23,6 +23,7 @@ fileprivate let identifierStarts: CharacterSet = {
 }()
 fileprivate let operators = CharacterSet(charactersIn: "+-*/<>=")
 fileprivate let expressionEnds = CharacterSet(charactersIn: ",]});")
+fileprivate let keywords = ["null", "true", "false"]
 
 class JavaScriptHighlighter {
     private var text: String!
@@ -244,6 +245,9 @@ class JavaScriptHighlighter {
         while let char = peek(), identifiers.contains(char) {
             consume()
         }
+        let identifier = text[identifierStart..<currentIndex]
+        let token: TokenType = keywords.contains(String(identifier)) ? .keyword : .identifier
+        emit(token: token, range: range(from: identifierStart, to: currentIndex))
         print("Identifier: '\(text[identifierStart..<currentIndex])'")
     }
 
@@ -452,6 +456,7 @@ class JavaScriptHighlighter {
 extension JavaScriptHighlighter {
     enum TokenType {
         case identifier
+        case keyword
         case punctuation
         case number
         case string(Unicode.Scalar)
@@ -463,9 +468,9 @@ extension JavaScriptHighlighter {
             case .number:
                 return .systemBlue
             case .punctuation:
-                return .systemTeal
-            case .identifier:
                 return nil
+            case .keyword, .identifier:
+                return .systemTeal
             }
         }
     }