;; -*- mode: common-lisp -*-
#|
clasm-6502: An assembler for the 6502 written in Common Lisp.
Copyright (C) 2024  Aleksei Eaves

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
|#

;; Rules for interpreting the purpose of some line.
(setf
 *grammar*
 '(
   (label
	(lambda (l)
	  (and (eq (last-char (first l)) #\:)
		   (eq (length l) 1))))
   (label-instruction
	(lambda (l)
	  (and (eq (last-char (first l)) #\:)
		   (member (read-from-string (second l)) *opcodes*))))
   (attribute
	(lambda (l)
	  (equal (char (first l) 0) #\.)))
   (instruction
	(lambda (l)
	  (member (read-from-string (first l)) *opcodes*)))
   (macro
	(lambda (l)
	  (equal (second l) "=")))   
   (unknown
	(lambda (l)
	  t))))


(defun syntax-rule (line list)
  "Apply a syntax rule against a delimited line from a program."
  (dolist (i (extract-keys list))
	(let ((z (funcall (eval (cadr (assoc i list)))
					  line)))
	  (if (not (equal
				z nil))
		  (return i)
		  nil))))


(syntax-rule '("LABEL:" "LDA" "$05") *grammar*)

(syntax-rule '("LDA" "$05") *grammar*)

(syntax-rule '("AS" "=" "THAT") *grammar*)

(syntax-rule '("LABEL:") *grammar*)

(syntax-rule '("hhhh") *grammar*)

(syntax-rule '(".org" "$FF00") *grammar*)