git-cherry filter

Is there a way to add a pre-git-patch-id filter to git-cherry?

e.g.,

(a) perform "keyword contraction" to the patch before generating the git-patch-id.

e.g. I want to run a git-cherry to see if two patches are identical other than keyword expansion values like $User: foo$ vs. $User: bar$. (I would have to tell git-cherry which keyword formats to "contract".)

(b) ignore comments in the source code.

e.g. I want to run a git-cherry to see if the patches are identical in regards to executable source. (I would have to tell git-cherry what the comment rules are for the various source files.)

(c) exclude certain files from the diff (ie., binaries, comment files, etc.).

e.g. I want to run a git-cherry to see which source code fixes from the old system have already been applied to the new system regardless of whether certain files differ (ie., binaries (ie, compile date), comment files (ie., fixed a typo), etc.). (I would have to tell git-cherry which paths/filenames to disregard.)

I suppose these may be git-patch-id options that are passed via git-cherry like the git-fetch options passable via git-pull.

v/r, neal

On Mon, Feb 13, 2012 at 10:20:59PM -0600, Neal Kreitzinger wrote:

Not directly, but see below.

Shouldn't these be contracted already in the canonical versions in the repo?

This one is tough, because you are talking about arbitrary transformation of the diff.

This one is perhaps easier, and git-cherry could learn to use the regular pathspec-limiting when generating patch-ids.

In any case, git-cherry is basically just comparing the set of patch ids in one set to the patch-ids in the other set. So you could do all of the above transformations by hacking together something like:

  merge_base=`git merge-base $upstream $head`
  get_patch_ids() {
    git rev-list $merge_base..$1 |
      git diff-tree --stdin -p -- $path_limiters |
      munge_your_diff_however_you_like |
      git patch-id
  }
  get_patch_ids $head >head
  get_patch_ids $upstream | cut -d' ' -f1 >upstream
  perl -l <<-\EOF
  open(my $head, '<', 'head');
  open(my $upstream, '<', 'upstream');
  my %upstream = map { $_ => 1 } <$upstream>;
  while (<$head>) {
          chomp;
          my ($patch, $commit) = split;
          print exists($upstream{$patch}) ? '+' : '-',
                ' ',
                $commit;
  }
  EOF

-Peff