From: Eli Zaretskii <eliz@gnu.org>
To: chen bin <chenbin.sh@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: [PATCH] add 'string-distance' to calculate Levenshtein distance
Date: Thu, 19 Apr 2018 11:05:52 +0300 [thread overview]
Message-ID: <83wox3zkm7.fsf@gnu.org> (raw)
In-Reply-To: <CAAE-R+-YRbMNMMt67hz2XHrBeAj+By4mhOo13vj_cuF-R=wJfw@mail.gmail.com> (message from chen bin on Tue, 17 Apr 2018 22:31:20 +1000)
> From: chen bin <chenbin.sh@gmail.com>
> Date: Tue, 17 Apr 2018 22:31:20 +1000
> Cc: emacs-devel@gnu.org
>
> As you suggested, I re-write the code using 'FETCH_STRING_CHAR_ADVANCE'.
Thanks.
> I also implemented the byte comparing version. It's 4 times as fast. And I do
> need use it to compare file path in my package 'counsel-etags'.
File names are just strings for this purpose, and they can potentially
include any non-zero characters. So I don't see why they are special.
> The fille path couldn't contain any funny characters (emoji). so
> it'sperfectly fine
> to use byte comparing version.
File names can very well include emoji and other "funny" characters,
Emacs supports that on all modern systems (including even MS-Windows).
> diff --git a/etc/NEWS b/etc/NEWS
> index 5aa92e2991..3cce2c48c7 100644
> --- a/etc/NEWS
> +++ b/etc/NEWS
> @@ -490,6 +490,8 @@ x-lost-selection-hooks, x-sent-selection-hooks
> +++
> ** New function assoc-delete-all.
>
> +** New function string-distance to calculate Levenshtein distance between two strings.
This long line should be filled using the fill-column setting we use
in NEWS. Even better, make the header a short summary, like
** New function 'string-distance'
and then describe its functionality in a separate sentence that starts
immediately below that header.
> +DEFUN ("string-distance", Fstring_distance, Sstring_distance, 2, 3, 0,
> + doc: /* Return Levenshtein distance between STRING1 and STRING2.
> +If BYTECOMPARE is nil, we compare character of strings.
> +If BYTECOMPARE is t, we compare byte of strings.
Please lose the "we" part, it's inappropriate in documentation,
because it describes what Emacs does.
> +Comparing by byte is faster and non-ascii characters has weighted distance.
I would delete this sentence, it is IMO confusing more than anything
else. (And I still think the bytewise comparison is not needed.)
> + bool use_bytecompare = !NILP(bytecompare);
^^
Space between these 2 characters.
> + else
> + {
> + int c1, c2;
> + ptrdiff_t i1, i1_byte, i2, i2_byte;
> + i2 = i2_byte = 0;
> + for (x = 1; x <= len2; x++)
Please move the initialization of i2 and i2_byte into the for-loop
initializer (suing the comma operator).
> + i1 = i1_byte = 0;
> + for (y = 1, lastdiag = x - 1; y <= len1; y++)
Likewise here with i1 and i1_byte.
Thanks.
next prev parent reply other threads:[~2018-04-19 8:05 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-14 2:35 [PATCH] add 'string-distance' to calculate Levenshtein distance Chen Bin
2018-04-14 7:05 ` Eli Zaretskii
[not found] ` <87lgdq831h.fsf@gmail.com>
2018-04-14 13:24 ` Eli Zaretskii
2018-04-14 16:40 ` Chen Bin
2018-04-14 17:08 ` Eli Zaretskii
2018-04-15 7:15 ` Chen Bin
2018-04-15 14:47 ` Eli Zaretskii
[not found] ` <CAAE-R+-RDWvyrv+uqHszzh6VMH6An3disOw=PyPWaTnUTHDOCw@mail.gmail.com>
[not found] ` <83k1t72b2o.fsf@gnu.org>
2018-04-17 2:43 ` chen bin
2018-04-17 15:44 ` Eli Zaretskii
2018-04-18 7:11 ` chen bin
[not found] ` <CAAE-R+8s++_LRcQCLX60Z=TQeQHdtbM5X1k525bfNnnPSLDvRw@mail.gmail.com>
[not found] ` <83bmei36dw.fsf@gnu.org>
2018-04-17 12:31 ` chen bin
2018-04-19 8:05 ` Eli Zaretskii [this message]
2018-04-19 14:55 ` chen bin
2018-04-20 4:37 ` chen bin
2018-04-20 6:01 ` Thien-Thi Nguyen
2018-04-20 10:47 ` chen bin
2018-04-21 7:22 ` Eli Zaretskii
2018-04-21 20:47 ` Juri Linkov
2018-04-28 7:36 ` Eli Zaretskii
2018-05-06 9:53 ` chen bin
2018-04-15 18:53 ` Paul Eggert
2018-04-14 17:18 ` Nathan Moreau
2018-04-14 17:36 ` Paul Eggert
2018-04-15 18:17 ` Andreas Politz
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