Grammar-based Context Handling

Abstract

The lexical analysis and parsing described in Chapters 2 and 3, applied to a program text, result in an abstract syntax tree (AST) with a minimal but important degree of annotation: the Token.class and Token.repr attributes supplied by the lexical analyzer as the initial attributes of the terminals in the leaf nodes of the AST. For example, a token representing an integer has the class ``integer'' and its value derives from the token representation; a token representing an identifier has the class ``identifier'', but completion of further attributes may have to wait until the identification mechanism has done its work.