ANTLRWorks: an ANTLR grammar development environment

Programmers tend to avoid using language tools, resorting to ad-hoc methods, because tools can be hard to use, their parsing strategies can be difficult to understand and debug, and their generated parsers can be opaque black-boxes. In particular, there are two very common difficulties encountered by grammar developers: Understanding why a grammar fragment results in a parser nondeterminism and determining why a generated parser incorrectly interprets an input sentence. This paper describes ANTLRWorks, a complete development environment for ANTLR grammars that attempts to resolve these difficulties and, in general, make grammar development more accessible to the average programmer. The main components are a grammar editor with refactoring and navigation features, a grammar interpreter, and a domain-specific grammar debugger. ANTLRWorks’ primary contributions are a parser nondeterminism visualizer based upon syntax diagrams and a time-traveling debugger that pays special attention to parser decision-making by visualizing lookahead usage and speculative parsing during backtracking.