use std::str::FromStr;
use std::rc::Rc;
use std::cell::RefCell;
use sl::Form;

grammar;

pub Term: Rc<Form> = {
    NUM => Rc::new(Form::Int(i32::from_str(<>).unwrap())),
    SYM => Rc::new(Form::Symbol(<>.to_owned())),
	"(" <ListInside?> ")" => <>.unwrap_or(Rc::new(Form::Nil)),
	"'" <Term> => Rc::new(Form::Pair(Rc::new(Form::Symbol("quote".to_owned())), Rc::new(Form::Pair(<>, Rc::new(Form::Nil))))),
	"!" <h: Term> <t: Term> => {
        h.append(t).unwrap()
     },
};
ListInside: Rc<Form> = {
	<Term> => Rc::new(Form::Pair(<>, Rc::new(Form::Nil))),
	<h: Term> <t: ListInside> => Rc::new(Form::Pair(h, t)),
	<a: Term> "." <d: Term> => Rc::new(Form::Pair(a, d)),
}
match {
    "(",
    ")",
    ".",
    "'",
    "!",
    r"[0-9]+"                                  => NUM,
    r"[a-zA-Z+*/_=?%&|^<>-][\w+*/=_?%&|^<>-]*" => SYM,
    r"(;[^\n]*\n)|\s+"                         => { }
}