;; print.stk -- a generic visitor for printing.

(require "visitor")

(define-method printf args (apply format #t args))

(define-visitor <print>
  :methods
  (
   (before <object>
     (printf "(~a" [class-name (class-of host)]))
   (after <object>
     (printf ")"))

   ;; printing a list
   (before <list>
     (printf "("))
   (after <list>
     (printf ")"))

   ;; printing a vector
   (before <vector>
     (printf "["))
   (after <vector>
     (printf "]"))

   ;; anything else (Terminal classes)
   (before <top>
     (printf "~s" host))
))

(define-method before ((visitor <print>) (s <object>) (e <edge>) t)
  (printf " :~a " [label e]))

(define-method before ((visitor <print>) (l <list>) (e <edge>) target)
  (unless (eq? (car l) target)
    ;; don't print anything before the first member of the list
    (printf " ")))

(define-method before ((visitor <print>) (v <vector>) (e <edge>) target)
  (unless (eq? (vector-ref v 0) target)
    ;; don't print anything before the first member of the vector
    (printf " ")))

(provide "print")