;;;  Define as funcoes logicas que nao estao no clisp:
;;;  impl e equ

(defun impl (a b)
  (or a (not b))
  )

(defun equ (a b)
  (not (xor a b))
  )

;;; Agora table, que constroi tabela de funcoes booleanas
;;; os parametros A e A sao as variaveis, e E e' a expressao booleana
;;; Esta aqui e' para expressoes infixas.

(defun table-in (a b e)
  (dolist (va (list t nil))
	  (dolist (vb (list t nil))
		  (format t "~S ~S ~S~%"
			  va vb
			  (bool-infix-eval a va b vb e)
			  )
		  )
	  )
  )

;;; Esta funcao avalia uma expressao infixa E em A e B
;;; dando-lhes valores VA e VB

(defun bool-infix-eval (a va b vb e)
  (cond
   ((eql e a) va)
   ((eql e b) vb)
   ((not (consp e)) 'invalida)
   ((eql (car e) 'not) (not (bool-infix-eval a va b vb (cadr e))))
   ((eql (cadr e) 'and) (and (bool-infix-eval a va b vb (car e))
			     (bool-infix-eval a va b vb (caddr e))
			     ))
   ((eql (cadr e) 'or) (or (bool-infix-eval a va b vb (car e))
			   (bool-infix-eval a va b vb (caddr e))
			   ))
   ((eql (cadr e) 'xor) (xor (bool-infix-eval a va b vb (car e))
			     (bool-infix-eval a va b vb (caddr e))
			     ))
   ((eql (cadr e) 'impl) (impl (bool-infix-eval a va b vb (car e))
			       (bool-infix-eval a va b vb (caddr e))
			       ))
   ((eql (cadr e) 'equ) (equ (bool-infix-eval a va b vb (car e))
			     (bool-infix-eval a va b vb (caddr e))
			     ))
   (t 'invalida)
   )
  )