From: Michael Haggerty <mhagger@alum.mit.edu>
To: Stefan Beller <sbeller@google.com>
Cc: "git@vger.kernel.org" <git@vger.kernel.org>,
"Junio C Hamano" <gitster@pobox.com>, "Jeff King" <peff@peff.net>,
"Jakub Narębski" <jnareb@gmail.com>,
"Jacob Keller" <jacob.keller@gmail.com>
Subject: Re: [PATCH 2/8] xdl_change_compact(): clarify code
Date: Wed, 10 Aug 2016 18:39:47 +0200 [thread overview]
Message-ID: <48ca79e2-418b-3c73-e075-808d39a4da9a@alum.mit.edu> (raw)
In-Reply-To: <CAGZ79kbyCRDTt4u+Fje819mNZZf3GkZtYVurwOMPXRfXqO-YEw@mail.gmail.com>
On 08/04/2016 01:50 AM, Stefan Beller wrote:
> On Wed, Aug 3, 2016 at 4:14 PM, Michael Haggerty <mhagger@alum.mit.edu> wrote:
>> On 08/04/2016 12:11 AM, Stefan Beller wrote:
>>> On Wed, Aug 3, 2016 at 3:00 PM, Michael Haggerty <mhagger@alum.mit.edu> wrote:
>>>> [...]
>>>> +
>>>> + /*
>>>> + * Are there any blank lines that could appear as the last
>>>> + * line of this group?
>>>> + */
>>>
>>> IIRC this comment is not quite correct as this 'only' counts the number of
>>> blank lines within the forward shifting section, i.e. in the movable space.
>>>
>>> Later we use it as a boolean indicator (whether or not it is equal to 0)
>>> to see if we can do better.
>>> [...]
Thanks for your comments, Stefan.
I realized that the main thing that took me a while to grok when I was
reading this code was that blank_lines was really only used as a boolean
value, even though it was updated with "+=". That's the main information
that I'd like to convey to the reader.
So I decided to change the comment to emphasize this fact (and change it
from a question to a statement), and also changed the place that
blank_lines is updated to treat it more like a boolean. The latter
change also has the advantage of not calling is_blank_line()
unnecessarily when blank_lines is already true.
If you have no objections, that is what I will put in v2 of this patch
series:
> diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c
> index de15de2..fde0433 100644
> --- a/xdiff/xdiffi.c
> +++ b/xdiff/xdiffi.c
> @@ -460,6 +460,12 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
>
> do {
> groupsize = i - start;
> +
> + /*
> + * Boolean value that records whether there are any blank
> + * lines that could be made to be the last line of this
> + * group.
> + */
> blank_lines = 0;
>
> /*
> @@ -511,7 +517,8 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) {
> * the current change group.
> */
> while (i < nrec && recs_match(recs, start, i, flags)) {
> - blank_lines += is_blank_line(recs, i, flags);
> + if (!blank_lines)
> + blank_lines = is_blank_line(recs, i, flags);
>
> rchg[start++] = 0;
> rchg[i++] = 1;
Michael
next prev parent reply other threads:[~2016-08-10 18:47 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-03 22:00 [PATCH 0/8] Better heuristics make prettier diffs Michael Haggerty
2016-08-03 22:00 ` [PATCH 1/8] xdl_change_compact(): rename some local variables for clarity Michael Haggerty
2016-08-04 7:06 ` Jeff King
2016-08-04 18:24 ` Junio C Hamano
2016-08-13 19:38 ` Michael Haggerty
2016-08-14 12:26 ` Jeff King
2016-08-03 22:00 ` [PATCH 2/8] xdl_change_compact(): clarify code Michael Haggerty
2016-08-03 22:11 ` Stefan Beller
2016-08-03 23:14 ` Michael Haggerty
2016-08-03 23:50 ` Stefan Beller
2016-08-04 7:13 ` Jeff King
2016-08-10 16:39 ` Michael Haggerty [this message]
2016-08-10 16:58 ` Stefan Beller
2016-08-03 22:00 ` [PATCH 3/8] xdl_change_compact(): rename i to end Michael Haggerty
2016-08-04 7:16 ` Jeff King
2016-08-03 22:00 ` [PATCH 4/8] xdl_change_compact(): do one final shift or the other, not both Michael Haggerty
2016-08-03 22:00 ` [PATCH 5/8] xdl_change_compact(): fix compaction heuristic to adjust io Michael Haggerty
2016-08-04 7:27 ` Jeff King
2016-08-10 16:58 ` Michael Haggerty
2016-08-10 17:09 ` Michael Haggerty
2016-08-11 4:16 ` Jeff King
2016-08-04 18:43 ` Junio C Hamano
2016-08-10 17:13 ` Michael Haggerty
2016-08-03 22:00 ` [PATCH 6/8] xdl_change_compact(): keep track of the earliest end Michael Haggerty
2016-08-04 18:46 ` Junio C Hamano
2016-08-10 17:16 ` Michael Haggerty
2016-08-03 22:00 ` [PATCH 7/8] is_blank_line: take a single xrecord_t as argument Michael Haggerty
2016-08-04 18:48 ` Junio C Hamano
2016-08-03 22:00 ` [PATCH 8/8] diff: improve positioning of add/delete blocks in diffs Michael Haggerty
2016-08-03 22:29 ` Jacob Keller
2016-08-03 22:36 ` Michael Haggerty
2016-08-04 4:47 ` Jacob Keller
2016-08-04 19:39 ` Junio C Hamano
2016-08-10 19:01 ` Michael Haggerty
2016-08-10 21:28 ` Junio C Hamano
2016-08-03 22:30 ` Stefan Beller
2016-08-03 22:41 ` Michael Haggerty
2016-08-03 22:51 ` Stefan Beller
2016-08-03 23:30 ` Michael Haggerty
2016-08-04 0:04 ` Stefan Beller
2016-08-10 19:12 ` Michael Haggerty
2016-08-04 7:56 ` Jeff King
2016-08-04 16:55 ` Stefan Beller
2016-08-04 19:47 ` Junio C Hamano
2016-08-13 0:09 ` Michael Haggerty
2016-08-12 23:25 ` Michael Haggerty
2016-08-13 8:59 ` Jeff King
2016-08-13 15:59 ` Junio C Hamano
2016-08-14 7:21 ` Jacob Keller
2016-08-15 6:33 ` Stefan Beller
2016-08-15 20:24 ` Junio C Hamano
2016-08-04 19:52 ` Junio C Hamano
2016-08-13 0:11 ` Michael Haggerty
2016-08-03 22:08 ` [PATCH 0/8] Better heuristics make prettier diffs Michael Haggerty
2016-08-04 7:38 ` Jeff King
2016-08-04 19:54 ` Junio C Hamano
2016-08-04 20:01 ` Jeff King
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