What do you mean with plugin structure?
There is a documentation file for how to use the add-on:
There is no documentation on the code itself, if that’s what you’re wondering. You’d have to figure it out from the code comments I’m afraid. In general the process is:
Scanning/lexing source to tokens → parse tokens into AST → transform AST into typed AST and resolve function overloading etc. → Compile typed AST into “bytecode”-like instructions → Interpret instruction into nodes