Function to get number of changed/deleted/added files for a single commit?

[dubcanada]

Hello,

I am wondering if there is currently a way to determine how many files are changed/deleted/added in a single commit? Something pretty much like

git show --pretty="format:" --name-only SHA | wc -l

Thanks!

[arrbee]

So, I think the easiest way to do this is:

/* get first commit and tree */
git_commit_lookup(&commit, repo, SHA);
git_commit_tree(&tree, commit);

/* get parent commit and tree - this assumes one parent, which is not safe */
git_commit_parent(&parent, commit, 0);
git_commit_tree(&parent_tree, parent);

/* get diff */
git_diff_tree_to_tree(&diff, repo, parent_tree, tree, NULL);

/* get your counts here */
printf("%d changed, %d added, %d deleted\n",
       (int)git_diff_num_deltas_of_type(diff, GIT_DELTA_MODIFIED),
       (int)git_diff_num_deltas_of_type(diff, GIT_DELTA_ADDED),
       (int)git_diff_num_deltas_of_type(diff, GIT_DELTA_DELETED));

Obviously you would want to do error checking and you'd need to do something more robust about handling the commit parents, but this is a quick approximation of what you want, I think. Note that in this case, git_diff_tree_to_tree is finding the file differences but not generating the text diffs between the files. You can use the diff object to generate those too, if you wish.

[arrbee]

@dubcanada Rereading this, I realize that you probably just need git_diff_num_deltas() after you have created the diff, since you are not trying to distinguish between added/deleted/modified and just want the overall count.

For merge commits, I believe the command as you have it will show files that are common to the diff against all parents. At the moment, libgit2 doesn't have an n-way diff nor a diff intersection operation, so you'd be stuck with generating the n diffs from each parent and iterating through them concurrently looking for files that appear in more than one diff. That's probably a little bit painful.

There are probably some new APIs in the works that could make dealing with those merge commits easier, but I wouldn't expect them particularly soon.

I'm hoping this answers your question, so I'm going to close the issue for now. If you have more questions or want to request a specific API that makes it easier to deal with merge commits or such, feel free to reopen this or just open a new issue!