https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/LispReader.java

This is the code that will read from a stream of chars into Clojure forms

Perfect. Thank you so much!

you are welcome

It is more like a json decoder than a traditional lexer/scanner

not to forget https://github.com/clojure/tools.reader, which is used by CLJS. same thing, just implemented in clj(s) and not java