Re: [PATCH] Improve contrib/diff-highlight to highlight unevenly-sized hunks
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Jun 18, 2015, 15:50 UTC
- Message-ID
- <xmqqwpz1f22b.fsf@gitster.dls.corp.google.com>
- In-Reply-To
- <1434388853-23915-1-git-send-email-patrick@parcs.ath.cx>
Patrick Palka <patrick@parcs.ath.cx> writes:
Show 11 quoted lines
> Currently the diff-highlight script does not try to highlight hunks that > have different numbers of removed/added lines. But we can be a little > smarter than that, without introducing much magic and complexity. > > In the case of unevenly-sized hunks, we could still highlight the first > few (lexicographical) add/remove pairs. It is not uncommon for hunks to > have common "prefixes", and in such a case this change is very useful > for spotting differences. > > Signed-off-by: Patrick Palka <patrick@parcs.ath.cx> > ---
Patrick, "git shortlog --no-merges contrib/diff-highlight/" is your friend to see who may be able to give you a good feedback.
Jeff, what do you think?
I have this nagging feeling that it is just as likely that two uneven hunks align at the top as they align at the bottom, so while this might not hurt it may not be the right approach for a better solution, in the sense that when somebody really wants to do a better solution, this change and the original code may need to be ripped out and redone from scratch.
Show 47 quoted lines
> contrib/diff-highlight/diff-highlight | 26 +++++++++++++++++---------
> 1 file changed, 17 insertions(+), 9 deletions(-)
>
> diff --git a/contrib/diff-highlight/diff-highlight b/contrib/diff-highlight/diff-highlight
> index ffefc31..0dfbebd 100755
> --- a/contrib/diff-highlight/diff-highlight
> +++ b/contrib/diff-highlight/diff-highlight
> @@ -88,22 +88,30 @@ sub show_hunk {
> return;
> }
>
> - # If we have mismatched numbers of lines on each side, we could try to
> - # be clever and match up similar lines. But for now we are simple and
> - # stupid, and only handle multi-line hunks that remove and add the same
> - # number of lines.
> - if (@$a != @$b) {
> - print @$a, @$b;
> - return;
> - }
> + # We match up the first MIN(a, b) lines on each side.
> + my $c = @$a < @$b ? @$a : @$b;
>
> + # Highlight each pair, and print each removed line of that pair.
> my @queue;
> - for (my $i = 0; $i < @$a; $i++) {
> + for (my $i = 0; $i < $c; $i++) {
> my ($rm, $add) = highlight_pair($a->[$i], $b->[$i]);
> print $rm;
> push @queue, $add;
> }
> +
> + # Print the remaining unmatched removed lines of the hunk.
> + for (my $i = $c; $i < @$a; $i++) {
> + print $a->[$i];
> + }
> +
> + # Print the added lines of each highlighted pair.
> print @queue;
> +
> + # Print the remaining unmatched added lines of the hunk.
> + for (my $i = $c; $i < @$b; $i++) {
> + print $b->[$i];
> + }
> +
> }
>
> sub highlight_pair {