AntlrVSIX is an extension for Visual Studio 2019 to support editing and refactoring of Antlr v4 grammars. It is implemented using Microsoft's Language Server Protocol (LSP) client and server APIs, Antlr, Antlr4BuildTasks, and a number of other tools. Most of the extension is implemented in C#, while the client for VS Code is in Typescript. Supported are colorized tagging, hover, go to def, find all refs, replace, command completion, reformat, and go to visitor/listener.
Instead of providing railroad diagrams and ATN graphs, this extension focuses on features useful for maintaining grammars, i.e., refactoring grammars in order to make them cleaner, more readable, and more efficient. Some of the refactorings implemented, or planned, include string literal folding, parser rule orderings, useless rule elimination, split combined grammars, combine split grammars, Flex/Bison import, removal of indirect left recursion, rule folding, rule unfolding, rule packing, and a "linter for Antlr grammars".
The source code for the extension is open source, free of charge, and free of ads. For the latest developments on the extension, check out my blog.
Release notes for v5.8:
For full version history, see the extension website.