Stephen B. Peckham

Globally Partitionable Attribute Grammars

The standard model for incremental attribute evaluation allows single subtree replacements followed by attribute reevaluation to restore consistency to a derivation tree. This paper advocates an extended model that allows multiple subtree replacements. In order to develop a static (tree-walking) algorithm for performing incremental updating after such changes, a subclass of attribute grammars is defined: globally partitionable attribute grammars (GPAGs). A new evaluator for GPAGs, GPAG-evaluate, may visit non-adjacent nodes, while guaranteeing that dependencies between attributes of each pair of nonterminals are respected. A polynomial-time test for determining whether an attribute grammar is GPAG is described, although the test will fail for some grammars that are GPAG.