ELIMINATING UNNECESSARY ITEMS FROM THE ONE-PASS EVALUATION OF ATTRIBUTE GRAMMARS

We present two efficient attribute evaluator construction methods for a wide subclass of L-attributed grammars by enumeration of attributed items during one-pass bottom-up parsing. We have already proposed a co nstruction method of a parser/evaluator for the subclass of L-arrribut ed grammar. However the evaluator produced by our previous method uses a great number of attributed items to evaluate all attributes of a gi ven input string. In this paper we propose two generalized methods to reduce the number of attributed items used in attribute evaluation. Ou r methods allow us to evaluate all attributes taking advantage of the use of available lookahead information.