;;; LALR(1) parser generator -- sample program
;;;
;;; (C) 2008 Gergő ÉRDI
;;; http://cactus.rulez.org/

(in-package :common-lisp-user)
(eval-when (:compile-toplevel :load-toplevel :execute)
  (require :lexer))
;;  (require :parser-shiftreduce))

(defpackage :cactus.parser-shiftreduce.example
  (:use :common-lisp :cactus.parser-shiftreduce :lexer)
  (:export :test))

(in-package :cactus.parser-shiftreduce.example)

(deflexer arithmetics-lexer
  ("[0-9]+"
   (return (values 'intlit (int %0))))
  ("[+*()]"
   (return %0))
  ("[:space:]+") )

(defparser/actions arithmetics-parser E  
  (E ((T)       (op)             op)
     ((E "+" T) (left nil right) (+ left right)))
  
  (T ((F)       (op)             op)
     ((T "*" F) (left nil right) (* left right)))
  
  (F (("(" E ")") (nil op nil) op)
     ((intlit)    (i)          (second i))))

(defun test (input)
  (labels ((terminal-matches-p (terminal token)
             (equal (car terminal) token)))
    (let* ((lex (arithmetics-lexer input))
           (tokens (loop for foo = (multiple-value-list (funcall lex))
                         while (car foo)
                         collecting foo)))
      (pprint (arithmetics-parser tokens #'terminal-matches-p)))))

(eval-when (:execute)
  (with-parser-debug-stream t
    (test "4 * (3 + 1) * 2 + (3 + 7)")))