narrow.el

## narrow.el

;; Narrow to the current buffer is somethimes weird because you loose
;; the ability to see other parts of the buffer.  One way is to first
;; create a clone of the current buffer. However, when this is
;; repeated, clones accumulate.

;; This hack just allows to kill clones when ending the narrowing,
;; allowing transparent workflow without manual buffer bookkeeping.


(defun my-kill-buffer-on-widen ()
  (kill-buffer)
  (advice-remove 'widen #'my-kill-buffer-on-widen))

(defun my-narrow-to-sexp ()
  (interactive)
  (let ((orig-point (point))
        start end)
    (cond ((region-active-p)
           (setq deactivate-mark t)
           (unless (< (point) (mark))
             (exchange-point-and-mark))
           (setq start (point)
                 end (mark)))
          (t
           (setq end (progn (forward-sexp) (point))
                 start orig-point)
           (goto-char orig-point)))
    (move-beginning-of-line 1)
    (let ((clone-buffer (clone-indirect-buffer nil nil))
          (narrow-start (point)))
      (with-current-buffer clone-buffer
        (goto-char start)
        (narrow-to-region narrow-start end)
        (advice-add 'widen :after #'my-kill-buffer-on-widen)
        (switch-to-buffer clone-buffer)))))