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0.0.8 • Public • Published


API and CLI to generate Abstract Syntax Trees (AST) of several well-known programming languages using antlr4 grammars

Playground - Demo

Playground (WIP)


  • JavaScript API for node.js and browser.
  • Command line tool
  • TypeScript
  • ASTs for C, golang, ruby, java, python, scala, erlang, lua, dart2, rust, antlr4, kotlin, smalltalk, fortran77, VisualBasic6, less wat, and more...

A word of caution

A word of caution regarding generated ASTs:

  • Not guaranteed to support 100% of Language's features
  • Not guaranteed to render 100% of given source code semantics
  • AST structure is not official
    • Was built using antlr4 which is not a tool oriented to generate AST
      • So some grammars needed to be post-processed to remove redundant nodes.


npm i univac

JavaScript API

import { parseAst } from 'univac'
const ast = await parseAst({
  input: 'int main() {}',
  language: 'c'
console.log(JSON.stringify(ast, null, 2))

Command line

univac --input src/file.py --language python3 --output file-ast.json
univac --listLanguages
univac --input "int main() {}" --language c > ast.json

Supported Languages

The idea is to support all languages in antlr4 grammars


THis is a very new project, WIP, this is the current status:

  • tests for Node.js API
  • tests to make sure it runs in the browser
  • C language
  • Golang
  • C++
  • scala
  • ruby
  • java
  • lua
  • python3
  • erlang
  • dart2
  • kotlin
  • Fortran77
  • Smalltalk
  • VisualBasic6
  • wat
  • less
  • java9 (very slow)
  • CLI
  • Basic Playground
  • playground improved with many examples, syntax hihgiling,different kind of ast viewers.
  • antlr4 grammar
  • c++ grammar (cppAntlr) - slow
  • introduced second kind of parser : tree-sitting. These return a "real" ast - not visitor.
    • declared adaptor interfaces
    • visitor is now a normalizer Normalizer
    • tree-sitter tests for node
    • async call parseAst()
  • rust (tree-sitter)
  • sexpressions (antlr4)
  • abnf (antlr4)
  • julia (tree-sitter)

Language grammars notes


Grammar taken from official readline-smalltalk project: https://github.com/redline-smalltalk/redline-smalltalk


Is not Ruby, is Ruby-like. Doesn't support Object Oriented features.

TODO: rename it or remove it. Notes from the author:

Ruby-like language (Corundum) grammar written in ANTLR v4. Was developed just for fun to use with Parrot VM (basically it compiles into PIR - parrot intermediate representation)

It has some specific stuff like inline pir and for loop :) And won't ever have OOP features, sorry.


It's very very slow, just use the java one. notes form the author:

A Java 8 grammar for ANTLR 4 derived from the Java Language Specification chapter 19.

NOTE: This grammar results in a generated parser that is much slower than the Java 7 grammar in the grammars-v4/java directory. This one is, however, extremely close to the spec.

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