Dynamically Bypassing Copy Rule Chains in Attribute Grammars

Abstract

Attribute grammars require copy rules to transfer values between attribute instances distant in an attributed parse tree. We introduce copy bypass attribute propagation that dynamically replaces copy rules with nonlocal dependencies, resulting in faster incremental evaluation. A evaluation strategy is used that approximates a topological ordering of attribute instances. The result is an efficient incremental evaluator that allows multiple subtree replacement on any noncircular attribute grammar.