Emacs: bulletproof up-list?

问题:

I'm getting up-list: Scan error: "Unbalanced parentheses" from this position:

(foo "bar|")

Snippet from up-list doc:

This command assumes point is not in a string or comment.

So this is the expected behavior. But I don't care. I just want to go upwards from a list. Could someone suggest an up-list clone that does the proper thing?

I'm looking for something better than this naive code:

(defun up-list-naive ()
  (interactive)
  (while (not (ignore-errors (up-list) t))
    (forward-char)))

回答1:

EDIT: incorporated Andreas Rohler's suggestion:

This works for me in your test case:

(defun my-up-list ()
  (interactive)
  (let ((s (syntax-ppss)))
    (when (nth 3 s)
      (goto-char (nth 8 s))))
  (ignore-errors (up-list)))

syntax-ppss returns a list, the third element of which exists if you're inside a string, and the 8th element is the beginning of the string (if you're in one, otherwise nil).

回答2:

In extension of answers given: deal with comments also, send "nil" when no further list found. When interactively called, message result.

(defun ar-up-list (arg)
  "Move forward out of one level of parentheses.
With ARG, do this that many times.

A negative argument means move backward but still to a less deep spot."
  (interactive "p")
  (let ((orig (point))
        (pps (syntax-ppss))
        erg)
    (and (nth 8 pps) (goto-char (nth 8 pps)))
    (ignore-errors (up-list arg))
    (and (< orig (point)) (setq erg (point)))
    (when (interactive-p) (message "%s" erg))
    erg))

And it's complement:

(defun ar-down-list (arg)
"Move forward down one level of parentheses.
With ARG, do this that many times.

A negative argument means move backward but still go down a level. "
  (interactive "p")
  (let ((orig (point))
        (pps (syntax-ppss))
        erg)
    (and (nth 8 pps) (goto-char (nth 8 pps)))
    (ignore-errors (down-list arg))
    (and (< orig (point)) (setq erg (point)))
    (when (interactive-p) (message "%s" erg))
    erg))