;; lib/maude/pretty.sx — mixfix surface-syntax printer.
;;
;; term->str renders the internal prefix form (`_+_(s_(X), 0)`); this renders
;; terms back in Maude mixfix surface syntax (`((s X) + 0)`), driven by the
;; operator forms in the module signature. Fully parenthesised — unambiguous
;; rather than minimal. Constants and unknown ops fall back to prefix form.

(define
  mau/render-forms
  (fn
    (m)
    (let
      ((tbl {}))
      (for-each
        (fn
          (op)
          (dict-set! tbl (get op :name) (mau/op-form (get op :name))))
        (mau/module-ops m))
      tbl)))

(define
  mau/render-args
  (fn
    (forms args)
    (cond
      ((empty? args) "")
      ((empty? (rest args)) (mau/render-term forms (first args)))
      (else
        (str
          (mau/render-term forms (first args))
          ", "
          (mau/render-args forms (rest args)))))))

(define
  mau/render-term
  (fn
    (forms t)
    (cond
      ((mau/var? t) (mau/vname t))
      ((mau/app? t)
        (let
          ((form (get forms (mau/op t))) (args (mau/args t)))
          (cond
            ((empty? args) (mau/op t))
            ((and form (= (get form :kind) "infix") (= (len args) 2))
              (str
                "("
                (mau/render-term forms (nth args 0))
                " "
                (get form :token)
                " "
                (mau/render-term forms (nth args 1))
                ")"))
            ((and form (= (get form :kind) "prefix") (= (len args) 1))
              (str
                "("
                (get form :token)
                " "
                (mau/render-term forms (first args))
                ")"))
            ((and form (= (get form :kind) "postfix") (= (len args) 1))
              (str
                "("
                (mau/render-term forms (first args))
                " "
                (get form :token)
                ")"))
            (else (str (mau/op t) "(" (mau/render-args forms args) ")")))))
      (else (str t)))))

(define
  mau/term->maude
  (fn (m t) (mau/render-term (mau/render-forms m) t)))

;; reduce / rewrite then render in surface syntax
(define
  mau/red->maude
  (fn (m src) (mau/term->maude m (mau/creduce-term m src))))

(define
  mau/rew->maude
  (fn (m src) (mau/term->maude m (mau/rewrite-term m src))))