Pogo2Ts

Use Antlr grammars to generate TypeScript models from POGOs (Plain Old Groovy Objects). With this side project I wanted to learn a little bit more about Antlr grammars and code generation.

This is kind of just a toy and would need a pretty good amount of work to be considered usable. I just wanted have some fun with this and get a simple case working.

General Idea

• Lex and parse POGOs using Antlr4
• Walk through each generated AST
• Generate TypeScript source for each POGO

Groovy Grammars

There are official Antlr4 grammars located in https://github.com/apache/groovy/blob/master/src/antlr/ . However, I found out the Parrot parser for Groovy uses a fork of Antlr4 (https://issues.apache.org/jira/browse/GROOVY-9232). This means that the official Antlr4 grammars don't work out of the box with the official Antlr4 jar.

After a lot of screwing around with trying to build the fork from https://github.com/tunnelvisionlabs/antlr4 , I decided I would just modify the existing Antlr4 Java8 grammars at https://github.com/antlr/grammars-v4/tree/master/java/java8 since Groovy is just a superset of Java.

Since I'm really just trying to convert POGOs, I will be skipping over the following items:

• Closures
• Metaprogramming
• All the cool Groovy string literal stuff - (interpolation, GStrings, etc)
• Probably much more...

My EBNF/Antlr is not strong enough to tackle these yet. If coerced enough I'd probably dive back in.

Setup (Windows)

• Download Antlr4 jar - https://www.antlr.org/download/antlr-4.8-complete.jar
• Add Antlr4 jar to CLASSPATH system variable
  • System Properties > Environment Variables > CLASSPATH (create if it doesn't exist)
  • Example: CLASSPATH = C:\Antlr4\antlr-4.8-complete.jar
• Create C:\Antlr4\antlr4.bat with the content java org.antlr.v4.Tool %* and add to PATH
• Generate lexer and parser using generate.bat
• Run program with dotnet run <directory_path>

Usage

• Run example files - dotnet run ../model/groovy ../model/ts com.github.barrettotte.model

References

• Antlr Mega Tutorial - https://tomassetti.me/antlr-mega-tutorial/
• The Definitive ANTLR4 Reference - https://pragprog.com/book/tpantlr2/the-definitive-antlr-4-reference
• Apache Groovy - https://github.com/apache/groovy
• Antlr4 Grammars - https://github.com/antlr/grammars-v4
• Groovy Grammar Resources
  • Groovy Language Documentation - https://docs.groovy-lang.org/latest/html/documentation/
  • Groovy Syntax - https://groovy-lang.org/syntax.html
  • Groovy Style Guide - https://groovy-lang.org/style-guide.html