Re: insert gives args out of range

[Stephen Berman <stephen.berman@gmx.net>]

On Fri, 16 Aug 2024 12:10:48 +0000 Heime <heimeborgia@protonmail.com> wrote:

> On Saturday, August 17th, 2024 at 12:03 AM, Heime <heimeborgia@protonmail.com> wrote:
>
>> On Friday, August 16th, 2024 at 11:51 PM, Stephen Berman
>> stephen.berman@gmx.net wrote:
>>
>> > On Fri, 16 Aug 2024 10:59:09 +0000 Heime heimeborgia@protonmail.com wrote:
>> >
>> > > On Friday, August 16th, 2024 at 10:20 PM, Heime
>> > > heimeborgia@protonmail.com wrote:
>> > >
>> > > > On Friday, August 16th, 2024 at 9:54 PM, Stephen Berman
>> > > > stephen.berman@gmx.net wrote:
>> > > >
>> > > > > On Fri, 16 Aug 2024 09:24:23 +0000 Heime heimeborgia@protonmail.com wrote:
>> > > > >
>> > > > > > I want to display text starting from "(defun" up to the second blank
>> > > > > > line that is encountered.
>> > > > > >
>> > > > > > But with this code I get
>> > > > > >
>> > > > > > insert: Args out of range: #<buffer Defun Sections>, 2706, 2804
>> > > > > >
>> > > > > > (defun display-text ()
>> > > > > > "Display the text between a line starting with '(defun' and the second
>> > > > > > blank line."
>> > > > > > (interactive)
>> > > > > > (let ((output-buffer (get-buffer-create "Defun Sections")))
>> > > > > > (with-current-buffer output-buffer
>> > > > > > (erase-buffer)) ;; Clear previous contents
>> > > > > > (save-excursion
>> > > > > > (goto-char (point-min))
>> > > > > > (while (re-search-forward "^(defun" nil t)
>> > > > > > (let ((start (match-beginning 0))
>> > > > > > (blank-lines 0)
>> > > > > > end)
>> > > > > > ;; Move forward to find the second blank line
>> > > > > > (while (and (< blank-lines 2)
>> > > > > > (re-search-forward "^\\s-*$" nil t))
>> > > > > > (setq blank-lines (1+ blank-lines)))
>> > > > > > (setq end (point))
>> > > > > > ;; Ensure the range is valid before inserting
>> > > > > > (when (> end start)
>> > > > > > (with-current-buffer output-buffer
>> > > > > > (insert (buffer-substring-no-properties start end) "\n"))))))
>> > > > > > ;; Display the output buffer
>> > > > > > (display-buffer output-buffer)))
>> > > > >
>> > > > > You've set `start' and` end' in a different buffer than output-buffer
>> > > > > but you're invoking buffer-substring-no-properties with these values in
>> > > > > output-buffer, which you've erased, so those values are not in the range
>> > > > > of possible values in output-buffer. Try let-binding the result of
>> > > > > invoking buffer-substring-no-properties before the second invocation of
>> > > > > with-current-buffer.
>> > > > >
>> > > > > Steve Berman
>> > >
>> > > I updated as suggested. Although I get the output, the search stops on
>> > > the first
>> > > blank line rather than on the second blank line.
>> >
>> > Consider a buffer "test" with the following content (two blank lines
>> > between the defuns):
>> >
>> > ;;;;;;;;;;;;;
>> >
>> > (defun f1 ()
>> > (ignore))
>> >
>> > (defun f2 ()
>> > (ignore))
>> > ;;;;;;;;;;;;;
>> >
>> > When you call `display-text' in "test", the first evaluation of the
>> > sexp (re-search-forward "^\\s-*$" nil t) moves point to the first blank
>> > line below the first defun. Where is point after the second evaluation
>> > of that sexp? - Steve Berman
>>
>>
>> It is still at the beginning of the first blank line.
>
> I do not understand why this happens.  Because (point) after
> re-search-forward should give me the position at the beginning of the
> second blank line that is encountered.

The sexp (re-search-forward "^\\s-*$" nil t) succeeds if it find a line
containing only zero or more whitespace characters and moves point to
the end of the match.  If point is on a blank line, the search succeeds,
but since the beginning and end of the match coincide, point does not
move.  If you want point to move, your code needs to accommodate this
case.

Steve Berman