From: Stefan Kangas <stefankangas@gmail.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>, JD Smith <jdtsmith@gmail.com>
Cc: Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org
Subject: Re: Temporarily select-window, without updating mode-line face and cursor fill?
Date: Tue, 4 May 2021 19:49:25 -0500 [thread overview]
Message-ID: <CADwFkmnUtg6mZH5XiAVfGZAnX-fOY+WipKDN8ETANEQ4s3=t9g@mail.gmail.com> (raw)
In-Reply-To: <jwvlf8wwogv.fsf-monnier+emacs@gnu.org>
Stefan Monnier <monnier@iro.umontreal.ca> writes:
> We really should simply speed up `line-number-at-pos`.
> It shouldn't be hard. See below what I do in nlinum.el.
Interesting, it seems much faster at least in this simplistic test:
(benchmark-run 100000 (line-number-at-pos))
=> (5.868677411999999 0 0.0)
(benchmark-run 100000 (line-number-at-pos))
=> (0.9772498589999999 1 0.5954873589998897)
Why not to just rename `line-number-at-pos' to
`internal--line-number-at-pos and install something much like the below
as `line-number-at-pos'?
> (defvar nlinum--line-number-cache nil)
> (make-variable-buffer-local 'nlinum--line-number-cache)
>
> ;; We could try and avoid flushing the cache at every change, e.g. with:
> ;; (defun nlinum--before-change (start _end)
> ;; (if (and nlinum--line-number-cache
> ;; (< start (car nlinum--line-number-cache)))
> ;; (save-excursion (goto-char start) (nlinum--line-number-at-pos))))
> ;; But it's far from clear that it's worth the trouble. The current simplistic
> ;; approach seems to be good enough in practice.
>
> (defun nlinum--after-change (&rest _args)
> (setq nlinum--line-number-cache nil))
>
> (defun nlinum--line-number-at-pos ()
> "Like `line-number-at-pos' but sped up with a cache.
> Only works right if point is at BOL."
> ;; (cl-assert (bolp))
> (if nlinum-widen
> (save-excursion
> (save-restriction
> (widen)
> (forward-line 0) ;In case (point-min) was not at BOL.
> (let ((nlinum-widen nil))
> (nlinum--line-number-at-pos))))
> (let ((pos
> (if (and nlinum--line-number-cache
> (> (- (point) (point-min))
> (abs (- (point) (car nlinum--line-number-cache)))))
> (funcall (if (> (point) (car nlinum--line-number-cache))
> #'+ #'-)
> (cdr nlinum--line-number-cache)
> (count-lines (point) (car nlinum--line-number-cache)))
> (line-number-at-pos))))
> ;;(assert (= pos (line-number-at-pos)))
> (add-hook 'after-change-functions #'nlinum--after-change nil :local)
> (setq nlinum--line-number-cache (cons (point) pos))
> pos)))
next prev parent reply other threads:[~2021-05-05 0:49 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-01 18:46 Temporarily select-window, without updating mode-line face and cursor fill? JD Smith
2021-05-01 19:31 ` Eli Zaretskii
2021-05-01 20:32 ` JD Smith
2021-05-02 6:49 ` Eli Zaretskii
2021-05-03 2:15 ` JD Smith
2021-05-03 7:50 ` martin rudalics
2021-05-03 16:16 ` JD Smith
2021-05-03 17:32 ` martin rudalics
2021-05-02 7:40 ` martin rudalics
2021-05-03 2:23 ` JD Smith
2021-05-01 22:17 ` JD Smith
2021-05-02 6:55 ` Eli Zaretskii
2021-05-03 2:08 ` JD Smith
2021-05-03 2:25 ` Stefan Monnier
2021-05-03 2:49 ` JD Smith
2021-05-04 19:28 ` JD Smith
2021-05-04 19:40 ` Stefan Monnier
2021-05-05 0:49 ` Stefan Kangas [this message]
2021-05-05 11:54 ` Eli Zaretskii
2021-05-05 19:32 ` Stefan Kangas
2021-05-05 19:47 ` Stefan Monnier
2021-05-06 0:16 ` JD Smith
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