Subclasses of Attribute Grammars

Abstract

This thesis is a contribution to the development of a formal theory for attribute grammars, their languages and their translations.

There are given precise definitions of an attribute grammar, the language recognized by the attribute grammar and the translation specified by the attribute grammar. The various definitions are compared with some alternative ones. Based on properties of the translation specified by an attribute grammar two new subclasses of attribute grammars are introduced: the determinate and the unambiguous attribute grammars.

Furthermore the concept of an evaluator is considered. Based on properties of an evaluator for an attribute grammar some new subclasses of attribute grammars are introduced: the k-visit attribute grammars and the k left-to-right pass attribute grammars (k is an integer). It turns out that the k-visit as well as the k left-to-right pass attribute grammars define proper hierarchies of translations when some conditions are satisfied. It is also shown that there are translations specified by 1-visit anribute grammars that cannot be specified by any k left-to-right pass attribute grammar (when some conditions are satisfied). On the other hand it turns out that any well-defined attribute grammar is k-visit for some k.