gistfile1.groovy

class UnwelcomeVisitorIterator {
   
  static public traverse( data, visitor ){
    if ( data instanceof Map ){
      data.each{ entrySet ->
        entrySet.value = visitor.visitMap( entrySet.key, entrySet.value )
        entrySet.value = traverse( entrySet.value, visitor )
      }
    } else if ( data instanceof Collection ){
      def processedList = []
      data.each{
        def visitedEntry = visitor.visitList( it )
        processedList << traverse( visitedEntry, visitor )
      }
      data = processedList
    }
    data
  }
}