From: Lars Ingebrigtsen <larsi@gnus.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: contovob@tcd.ie, emacs-devel@gnu.org
Subject: Re: Searching for line beginning
Date: Mon, 15 Aug 2022 06:28:05 +0200 [thread overview]
Message-ID: <87bksmf7vu.fsf@gnus.org> (raw)
In-Reply-To: <83o7wmkeqo.fsf@gnu.org> (Eli Zaretskii's message of "Sun, 14 Aug 2022 18:48:47 +0300")
By the way, I see that Fline_beginning_position/end have grown field
capabilities while I wasn't looking (in 2000). I.e., they call
Fconstrain_to_field, which is a pretty complex function. This means
that rewriting a loop like
(let ((sum 0))
(goto-char (point-min))
(while (not (eobp))
(goto-char (line-end-position))
(setq sum (+ sum (point)))
(forward-char 1))
sum)
into
(let ((sum 0))
(goto-char (point-min))
(while (not (eobp))
(forward-line 1)
(setq sum (+ sum (1- (point)))))
sum)
is more than twice as fast, which is sad. (Because `forward-line'
doesn't do the field stuff.)
The field stuff only makes sense in user-oriented buffers, while we use
line-end-position extensively in Emacs to parse buffers in general --
but we get this field penalty throughout Emacs.
next prev parent reply other threads:[~2022-08-15 4:28 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-13 15:43 Searching for line beginning Eli Zaretskii
2022-08-13 16:20 ` Stefan Monnier
2022-08-13 17:58 ` Eli Zaretskii
2022-08-14 12:54 ` Eli Zaretskii
2022-08-14 15:33 ` Basil L. Contovounesios
2022-08-14 15:36 ` Eli Zaretskii
2022-08-14 15:43 ` Lars Ingebrigtsen
2022-08-14 15:48 ` Eli Zaretskii
2022-08-15 4:28 ` Lars Ingebrigtsen [this message]
2022-08-15 11:29 ` Eli Zaretskii
2022-08-15 11:37 ` Lars Ingebrigtsen
2022-08-15 12:00 ` Eli Zaretskii
2022-08-17 2:49 ` Richard Stallman
2022-08-17 10:41 ` Lars Ingebrigtsen
2022-08-17 11:48 ` Eli Zaretskii
2022-08-17 11:52 ` Stefan Monnier
2022-08-18 12:37 ` Lars Ingebrigtsen
2022-08-14 17:24 ` Stefan Monnier
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