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From: Phillip Wood <phillip.wood@talktalk.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: Git Mailing List <git@vger.kernel.org>,
	Ævar Arnfjörð Bjarmason <avarab@gmail.com>,
	Igor Djordjevic <igor.d.djordjevic@gmail.com>,
	Phillip Wood <phillip.wood@dunelm.org.uk>
Subject: Re: [RFC PATCH v5 2/4] add -p: select modified lines correctly
Date: Fri, 27 Jul 2018 11:19:38 +0100
Message-ID: <2e78e077-1801-9c92-6b53-badf588fe262@talktalk.net> (raw)
In-Reply-To: <xmqqmuudpzfl.fsf@gitster-ct.c.googlers.com>

Hi Junio, thanks for the comments

On 26/07/18 20:30, Junio C Hamano wrote:
> Phillip Wood <phillip.wood@talktalk.net> writes:
> 
> An interesting problem you are solving ;-)
> 
>> For example given the hunk
>>       1 -* a longer description of the
>>       2 -  first item
>>       3 -* second
>>       4 -* third
>>       5 +* first
>>       6 +  second item
>>       7 +* the third item
>>
>> If the user selects 1,2,4–5,7 then we should generate
>> 	-* a longer description of the
>> 	-  first item
>> 	+* first
>> 	 * second
>> 	-* third
>> 	+* the third item
> 
> I understood this example as "3 that is removal and 6 that is
> addition are excluded---we consider that these two lines (one in the
> pre-image and the other in the post-image) are _matching" As we> are excluding a deletion, it becomes the common context line, and
> any removal or addition that appear before that must stay to happen
> before the common context line (i.e. removal of 1 and 2, and
> addition of 5, both precede common context line "second") and any
> removal or addition that appear after that must stay after the
> common context (i.e. removal of "third" and addition of "the third
> item" come after "second").
> 
> But then it is not clear to me what you mean by "group" below.  What
> groups does the above example have?  Ones before the retained
> "second" (i.e. removal 1, 2, 4 and addition 5) form one group and
> ones after it (i.e. removal 4 and addition 7) form another group?

The code actually looks at the lines that are selected rather than
omitted. So in the example above it groups them as [1,2] (because they
are contiguous), [4],[5] (these are split because one is an insertion
and one a deletion) and [7]. It then sees that there are two groups of
deletions ([1,2],[4]) and two groups of insertions ([5],[7]) and so
pairs up the deletions in [12] with the insertion in [5] and likewise
with [4] and [7]. Lines 3 and 6 are never explicitly paired, although
they basically behave as if they were. One the insertions are all paired
up it walks over the list and creates a new hunk where the paired
insertions come immediately after their corresponding deletions,
unselected deletions are converted to context lines and unselected
additions are dropped.

> 
>> Reported-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> 
> Is this fixing any bug?  I usually see "Reported-by" only for a
> bugfix patch but this seems to be adding a new feature (and lack of
> feature is usually not a bug).

I guess I meant that the previous series was effectively buggy as it
would give the wrong result for modified lines. I wanted to acknowledge
that Ævar spent some time testing it and pointed that out.

Best Wishes

Phillip


  reply index

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-19 11:36 [PATCH v1 0/3] add -p: select individual hunk lines Phillip Wood
2018-02-19 11:36 ` [PATCH v1 1/3] " Phillip Wood
2018-02-19 11:36 ` [PATCH v1 2/3] add -p: allow line selection to be inverted Phillip Wood
2018-02-19 11:36 ` [PATCH v1 3/3] add -p: optimize line selection for short hunks Phillip Wood
2018-02-19 12:20 ` [PATCH v1 0/3] add -p: select individual hunk lines Gustavo Leite
2018-03-06 10:17 ` [PATCH v2 " Phillip Wood
2018-03-06 10:17   ` [PATCH v2 1/3] " Phillip Wood
2018-03-06 20:29     ` Igor Djordjevic
2018-03-06 21:33       ` Igor Djordjevic
2018-03-06 10:17   ` [PATCH v2 2/3] add -p: allow line selection to be inverted Phillip Wood
2018-03-06 19:57     ` Junio C Hamano
2018-03-08 11:05       ` Phillip Wood
2018-03-08 17:53         ` Junio C Hamano
2018-03-13 12:06           ` Phillip Wood
2018-03-13 16:32             ` Junio C Hamano
2018-03-14 11:02               ` Phillip Wood
2018-03-06 20:41     ` Igor Djordjevic
2018-03-06 10:17   ` [PATCH v2 3/3] add -p: optimize line selection for short hunks Phillip Wood
2018-03-06 20:33     ` Igor Djordjevic
2018-03-06 20:19   ` [PATCH v2 0/3] add -p: select individual hunk lines Igor Djordjevic
2018-03-06 21:03     ` Junio C Hamano
2018-03-06 21:20       ` Igor Djordjevic
2018-03-16 10:13 ` [PATCH v3 " Phillip Wood
2018-03-16 10:13   ` [PATCH v3 1/3] " Phillip Wood
2018-03-16 10:13   ` [PATCH v3 2/3] add -p: allow line selection to be inverted Phillip Wood
2018-03-16 10:13   ` [PATCH v3 3/3] add -p: optimize line selection for short hunks Phillip Wood
2018-03-29 18:32   ` [PATCH v3 0/3] add -p: select individual hunk lines Junio C Hamano
2018-03-30 11:09     ` Phillip Wood
2018-03-31 19:20       ` Ævar Arnfjörð Bjarmason
2018-04-02 10:55         ` Phillip Wood
2018-04-02 11:39           ` Ævar Arnfjörð Bjarmason
2018-07-26 10:22 ` [RFC PATCH v4 0/4] " Phillip Wood
2018-07-26 10:22   ` [PATCH v4 1/4] " Phillip Wood
2018-07-26 10:22   ` [RFC PATCH v4 2/4] add -p: select modified lines correctly Phillip Wood
2018-07-26 10:22   ` [PATCH v4 3/4] add -p: allow line selection to be inverted Phillip Wood
2018-07-26 10:22   ` [PATCH v4 4/4] add -p: optimize line selection for short hunks Phillip Wood
2018-07-26 15:58 ` [RFC PATCH v5 0/4] add -p: select individual hunk lines Phillip Wood
2018-07-26 15:58   ` [PATCH v5 1/4] " Phillip Wood
2018-07-26 19:36     ` Junio C Hamano
2018-07-27 10:05       ` Phillip Wood
2018-07-27 16:09         ` Junio C Hamano
2018-07-26 15:58   ` [RFC PATCH v5 2/4] add -p: select modified lines correctly Phillip Wood
2018-07-26 19:30     ` Junio C Hamano
2018-07-27 10:19       ` Phillip Wood [this message]
2018-07-27 16:14         ` Junio C Hamano
2018-07-26 15:58   ` [PATCH v5 3/4] add -p: allow line selection to be inverted Phillip Wood
2018-07-26 15:58   ` [PATCH v5 4/4] add -p: optimize line selection for short hunks Phillip Wood
2018-07-27 18:27   ` [RFC PATCH v5 0/4] add -p: select individual hunk lines Ævar Arnfjörð Bjarmason
2018-07-28 10:08     ` Phillip Wood
2018-07-28 12:40   ` Ævar Arnfjörð Bjarmason
2018-08-03 10:01     ` Phillip Wood
2018-08-03 16:51       ` Junio C Hamano
2018-08-03 17:59       ` Ævar Arnfjörð Bjarmason

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