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#lang racket/base
(provide fresh-line
zero-column!)
;; Borrowed from xrepl
(define last-output-port (make-parameter #f))
(define last-error-port (make-parameter #f))
(define (maybe-new-output-ports)
(define (maybe last cur)
(unless (eq? (last) (cur))
(when (and (last)
(not (port-closed? (last))))
(flush-output (last))) ;just in case
(last (cur))
(flush-output (last))
(port-count-lines! (last))))
(maybe last-output-port current-output-port)
(maybe last-error-port current-error-port))
(define (fresh-line [stderr? #f])
(maybe-new-output-ports)
(define port (if stderr? (last-error-port) (last-output-port)))
(flush-output port)
(define-values [line col pos] (port-next-location port))
(unless (eq? col 0) (newline)))
(define (zero-column!)
;; there's a problem whenever there's some printout followed by a
;; read: the cursor will be at column zero, but the port counting
;; will think that it's still right after the printout; call this
;; function in such cases to adjust the column to 0.
(maybe-new-output-ports)
(define-values [line col pos] (port-next-location (last-output-port)))
(set-port-next-location! (last-output-port) line 0 pos))
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