I would also recommend looking at the code generated by Lex and Yacc as well as hand-written code to parse a Lisp or Scheme. That might give an idea of how to o

I would also recommend looking at the code generated by Lex and Yacc as well as hand-written code to parse a Lisp or Scheme. That might give an idea of how to organize a hand-written parser. Though, without reading Modern Compiler Implementation or something similar the use of shift-reduce tables in generated code might not make sense. Also, my computer science curriculum included a course where we wrote a top-down LL(1) parser which is organized very differently with a function call for parsing each rule which calls other functions for parsing sub-rules etc. I've hand-written a few mangled char-by-char state machines as well, which served as lexers for various DSLs.