ANTLR Grammar Testing Tool

Kotlin ANTLR grammar correctness verification by comparing trees created both with ANTLR autogenerated parser and the real parser.

Input	Output
Kotlin language source code	Parsing and comparison report with ability to check out the subtrees in which the difference was found

Workflow description

• The KotlinFileContext object is created using the generated by ANTLR tool KotlinLexer and KotlinParser classes. If parsing errors are detected, no further validation occurs
• The real AST stored in KtFile object is generated using Kootstrap
• For future analysis the resulting objects are wrapped into auxiliary wrapper classes
• The comparison is recursive. If a difference in the subtrees is found, the information is stored as an ComparisonError object, and verification continues

Comparison logic

• There are several ANTLR rules which can be considered as redundant. Redundant rules are created just to simplify the grammar and skipped when verified
• Our goal is to check if the trees are homeomorphic by smoothing out vertices from the ANLTR-generated parse tree

Grammar source

Source