;;; I'm trying to write an interpreter for a BBC BASIC subset
;;; initially following the design of
;;; https://caml.inria.fr/pub/docs/oreilly-book/html/book-ora058.html
;;; and later I can Frankenstein it with
;;; https://github.com/Henry/BuddKaminInterpreters

(load "cutil.lisp")
(load "cparse.lisp")
(require "cparse")
(defpackage #:cbasic
  (:use #:common-lisp)
  (:export
   #:main))
(in-package #:cbasic)

;;; Not sure if it's a good idea,
;;; but try to keep the number of top-level functions the same as in OCaml.

(defun one-command (st)
  (format (standard-output) "> ")
  (with-handler #'error-handler
    (let ((l (parse (read-line))))
      (case (car l)
        ((line) (insert (cadr c)))
        ((p-end) (throw 'end nil)))))) ; throw and conditions are orthogonal

(defclass <state> () ((program :accessor program)
                      (env :accessor env)))
(defmethod initialize-object :after ((self <state>) initargs)
  (setf (program self) nil)
  (setf (env self) nil))

(defun main ()
  (catch 'end (lambda ()
                (format (standard-output) "BASIC version 0.1~%~%")
                (for ((st (create (class <state>))))
                     (catch 'error (one-command st)))))
  (format (standard-output) "See you later...~%"))
(provide "cbasic")