GNU bug report logs - #22763
25.1.50; Feature Request -- A faster method to obtain line number at position.

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From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 22763 <at> debbugs.gnu.org, Eli Zaretskii <eliz <at> gnu.org>, Keith David Bershatsky <esq <at> lawlist.com>
Subject: bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position.
Date: Sun, 07 Feb 2021 18:45:51 +0100

Stefan Monnier <monnier <at> iro.umontreal.ca> writes:

> Why is it faster?
>
> Is it still always Θ(N) just with a smaller constant (if so, what makes
> the constant smaller), or does it benefit from some kind of caching
> (which I fail to see in the code) such that it's O(N) sometimes but much
> faster other times (and if so, what are the cases that are sped up)?

There's no caching.  I guess find_newline is just slow compared to
display_count_lines?  (How many of these functions do we have in the C
layer, anyway?)

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

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