Elkhound: A Fast, Practical GLR Parser Generator

The Generalized LR (GLR) parsing algorithm is attractive for use in parsing programming languages because it is asymptotically efficient for typical grammars, and can parse with any context-free grammar, including ambiguous grammars. However, adoption of GLR has been slowed by high constant-factor overheads and the lack of a general, user-defined action interface. In this paper we present algorithmic and implementation enhancements to GLR to solve these problems. First, we present a hybrid algorithm that chooses between GLR and ordinary LR on a token-by-token basis, thus achieving competitive performance for determinstic input fragments. Second, we describe a design for an action interface and a new worklist algorithm that can guarantee bottom-up execution of actions for acyclic grammars. These ideas are implemented in the Elkhound GLR parser generator. To demonstrate the effectiveness of these techniques, we describe our experience using Elkhound to write a parser for C++, a languag...

• Type: Conference
• Year: 2004
• Where: CC
• Authors: Scott McPeak, George C. Necula
• Keywords: Action Interface, Algorithm, CC 2004, Elkhound GLR Parser, Programming Languages