Logic-based specification of visibility rules

Abstract

The paper describes a new, declarative method for the formal specification of visibility rules. In contrast to common methods that are based on the specification of a symboltable (or environment), of appropriate update operations and of passing rules, the presented method is related to visibility descriptions in language reports. It consists of three steps: First, the program entities are specified, i.e. the candidates for the meaning of an identifier; the next step defines the ranges where the program entities are valid or hidden; finally, visibility is expressed in terms of these ranges. To formally define the semantics of these visibility specifications, a modeltheoretic view of abstract syntaxtrees is sketched. Using this framework, we give a fixpoint semantics for such specifications.