;; pretty-print.stk -- a generic visitor for printing with nice indentation.

(require "visitor")
(require "print")

(define-visitor <pretty-print>
  :extends <print>
  :locals ((indent-level :initform 0))
  :methods
  (
   (inc-indent (inc <integer>)
     (set! indent-level (+ indent-level inc)))
   (dec-indent (dec <integer>)
     (set! indent-level (- indent-level dec)))

   (before <list>
     (next-method)
     (inc-indent vis 1))
   (after <list>
     (dec-indent vis 1)
     (next-method))

   (before <vector>
     (next-method)
     (inc-indent vis 1))
   (after <vector>
     (dec-indent vis 1)
     (next-method))
))

(define-method before ((p <pretty-print>) (s <object>) (e <edge>) t)
  (indent p)
  (next-method)
  (inc-indent p (+ (string-length (symbol->string [label e])) 3)))
(define-method after ((p <pretty-print>) (s <object>) (e <edge>) t)
  (dec-indent p (+ (string-length (symbol->string [label e])) 3))
  (next-method))

(define-method before ((p <pretty-print>) (l <list>) (e <edge>) (t <object>))
  (next-method)
  (unless (eq? (car l) t)
    ;; don't print a newline before the first member of the list
    (indent p)))

(define-method before ((p <pretty-print>) (v <vector>) (e <edge>) (t <object>))
  (next-method)
  (unless (eq? (vector-ref v 0) t)
    ;; don't print a newline before the first member of the vector
    (indent p)))

(define-method indent ((p <pretty-print>))
  (printf (string-append "~%" (make-string [indent-level p] #\space))))

(provide "pretty-print")