LL(1) Conflict Resolution in a Recursive Descent Compiler Generator

Albrecht Wöß
Institut für Praktische Informatik
woess@ssw.uni-linz.ac.at

Markus Löberbauer
Institut für Praktische Informatik
loeberbauer@ssw.uni-linz.ac.at

Hanspeter Mössenböck
Institut für Praktische Informatik
moessenboeck@ssw.uni-linz.ac.at

Abstract

Recursive descent parsing is restricted to languages whose grammars are LL(1), i.e., which can be parsed top-down with a single lookahead symbol. Unfortunately, many languages such as Java, C++, or C# are not LL(1). There-fore recursive descent parsing cannot be used or the parser has to make its deci-sions based on semantic information or a multi-symbol lookahead.

In this paper we suggest a systematic technique for resolving LL(1) conflicts in recursive descent parsing and show how to integrate it into a compiler gen-erator (Coco/R). The idea is to evaluate user-defined boolean expressions, in order to allow the parser to make its parsing decisions where a one symbol loo-kahead does not suffice.

Using our extended compiler generator we implemented a compiler front end for C# that can be used as a framework for implementing a variety of tools.

Proceedings of the Joint Modular Languages Conference (JMLC'03), Klagenfurt, August 2003, Lecture Notes in Computer Science

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