Epsilon-production bug of CL-YACC

eplislon-production-bug-of-cl-yacc.lisp

;; BUG1: Unnecessary readin tokens
(in-package :cl-user)

(yacc:define-parser *parser*
  (:start-symbol start)
  (:terminals ())
  (start))

(yacc:parse-with-lexer (lambda () (error "BUG")) *parser*)

;; BUG2: Handling epsilon production
(in-package :cl-user)

(yacc:define-parser *parser*
  (:start-symbol start)
  (:terminals (:foo :bar))
  (start (optional1 optional2))
  (optional1 (:foo)
             ;())
             (none))
  (optional2 (:bar)
             ())
  (none ()))

(defun list-lexer (list) (lambda () (pop list)))

(yacc:parse-with-lexer (list-lexer '(:bar)) *parser*)