Re: Proposal: make up-list escape strings

[Andreas Röhler]

Am 09.04.2014 01:14, schrieb Daniel Colascione:
> Here's a small patch that makes backward-up-list and up-list escape
> strings as well as explicit lists. This behavior is active only when
> these functions are called interactively or when lisp explicitly asks
> for this behavior, so the change shouldn't pose a compatibility risk.
> Backing out of strings is generally a useful thing to do when you want
> to operate on the string as a whole.
>
> === modified file 'lisp/emacs-lisp/lisp.el'
> --- lisp/emacs-lisp/lisp.el     2014-02-26 02:31:27 +0000
> +++ lisp/emacs-lisp/lisp.el     2014-04-08 23:12:16 +0000
> @@ -140,38 +140,58 @@
>         (goto-char (or (scan-lists (point) inc -1) (buffer-end arg)))
>         (setq arg (- arg inc)))))
>
> -(defun backward-up-list (&optional arg)
> +(defun backward-up-list (&optional arg escape-strings)
>     "Move backward out of one level of parentheses.
>   This command will also work on other parentheses-like expressions
>   defined by the current language mode.
>   With ARG, do this that many times.
>   A negative argument means move forward but still to a less deep spot.
> -This command assumes point is not in a string or comment."
> -  (interactive "^p")
> -  (up-list (- (or arg 1))))
> +This command assumes point is not in a string or comment.
> +If ESCAPE-STRINGS is non-nil (as it is interactively), treat
> +encoding strings as sexps."
> +  (interactive "^p\nd")
> +  (up-list (- (or arg 1)) escape-strings))
>
> -(defun up-list (&optional arg)
> +(defun up-list (&optional arg escape-strings)
>     "Move forward out of one level of parentheses.
>   This command will also work on other parentheses-like expressions
>   defined by the current language mode.
>   With ARG, do this that many times.
>   A negative argument means move backward but still to a less deep spot.
> -This command assumes point is not in a string or comment."
> -  (interactive "^p")
> +If ESCAPE-STRINGS is non-nil (as it is interactively), treat
> +encoding strings as sexps."
> +  (interactive "^p\nd")
>     (or arg (setq arg 1))
>     (let ((inc (if (> arg 0) 1 -1))
>           pos)
>       (while (/= arg 0)
>         (if (null forward-sexp-function)
> -          (goto-char (or (scan-lists (point) inc 1) (buffer-end arg)))
> +          (condition-case err
> +              (goto-char (or (scan-lists (point) inc 1) (buffer-end arg)))
> +            (scan-error
> +             (or (and escape-strings
> +                      (let ((syntax (syntax-ppss)))
> +                        (and (nth 3 syntax)
> +                             (nth 8 syntax))
> +                        (goto-char (nth 8 syntax))
> +                        (when (> arg 0) (forward-sexp))
> +                        t))
> +                 (signal (car err) (cdr err)))))
>         (condition-case err
>             (while (progn (setq pos (point))
>                           (forward-sexp inc)
>                           (/= (point) pos)))
>           (scan-error (goto-char (nth (if (> arg 0) 3 2) err))))
>         (if (= (point) pos)
> -            (signal 'scan-error
> -                    (list "Unbalanced parentheses" (point) (point)))))
> +            (or (and escape-strings
> +                     (let ((syntax (syntax-ppss)))
> +                       (and (nth 3 syntax)
> +                            (nth 8 syntax))
> +                       (goto-char (nth 8 syntax))
> +                       (when (> arg 0) (forward-sexp))
> +                       t))
> +             (signal 'scan-error
> +                     (list "Unbalanced parentheses" (point) (point))))))
>         (setq arg (- arg inc)))))
>
>   (defun kill-sexp (&optional arg)

Probably the most ancient bug :-)

IMO you don't need "and" going out of comments/strings

just (goto-char (nth 8 syntax))


Here is the form I'm using for ages:

(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))

Cheers,

Andreas