“…None of them considered complex tree traversals as attribute grammars. On the other hand, there have been many studies on parallel evaluation of attribute grammars [3], [14], [16], [17], [19], [23], [30], [31], but most of them do not guarantee parallel speedups. A notable exception is Reps' scan grammars [30], which provided an efficiency-guaranteed parallel implementation for an attribution that scans leaves by using an associative operator.…”