[PATCH/RFC] Add a --bouquet option to git rev-list

["Nathan W. Panike" <nathan.panike@gmail.com>]

Add a command line option to rev-list so the command 'git rev-list --bouquet'
shows all revisions that are ancestors of refs which share history with HEAD.

Signed-off-by: Nathan W. Panike <nathan.panike@gmail.com>
---
I have a repository with the following structure:

      B
     /
A'--A--C
     \
      D

E'--E

Thus the command 'git merge base E A' returns nothing, as there is no common
history.  The E history contains stuff that is derived from the other history
(A, B, C, or D).  Often I find myself doing the following:

git checkout C
gitk $(include_forks) &
<View history, make changes, merges, et cetera>
git checkout E
<go back to gitk, only see history for B, C, etc>

Now the 'include_forks' command is a bash function in my .bashrc:

include_forks () 
{ 
    local head="$(git show -s --pretty=format:'%H' HEAD)";
    echo "HEAD $(git for-each-ref --format='%(refname)' \
	refs/heads refs/remotes | while read ref; do \
	if test "$(git merge-base HEAD ${ref}^{commit})" != ""; \
		then echo ${ref}; fi; done)"
}

The shell thus intercepts my command and I must restart gitk to see the history
of E. 

With this patch, I can issue the command 'gitk --bouquet' and when I checkout
E, I can 'reload' in gitk and see the history of E automatically.

If there is an easier way to do this in git, please let me know.  Otherwise,
please let me know how to improve this patch.

 revision.c |   38 ++++++++++++++++++++++++++++++++++++++
 1 files changed, 38 insertions(+), 0 deletions(-)

diff --git a/revision.c b/revision.c
index a8a3c3a..ba367cc 100644
--- a/revision.c
+++ b/revision.c
@@ -699,6 +699,31 @@ static int handle_one_ref(const char *path, const unsigned char *sha1, int flag,
 	return 0;
 }
 
+static int handle_one_connected_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
+{
+	struct all_refs_cb *cb = cb_data;
+	struct object *object = get_reference(cb->all_revs, path, sha1,
+					      cb->all_flags);
+	struct commit *r;
+	static int got_head = 1;
+	static struct commit *head_commit;
+	static int head_nr = 0;
+	if(got_head) {
+		got_head=head_ref(handle_one_ref,cb);
+		if(got_head)
+			return 1;
+		if(cb && cb->all_revs && cb->all_revs->pending.nr > 0) {
+			head_nr = cb->all_revs->pending.nr - 1;
+			head_commit = (struct commit*)&cb->all_revs->pending.objects->item[head_nr];
+		}
+	}
+	r = lookup_commit_reference_gently(sha1,1);
+	if(r != NULL && head_commit)
+		if(get_merge_bases_many(head_commit,1,&r,1)) 
+			add_pending_object(cb->all_revs, object, path);
+	return 0;
+}
+
 static void handle_refs(struct rev_info *revs, unsigned flags,
 		int (*for_each)(each_ref_fn, void *))
 {
@@ -708,6 +733,15 @@ static void handle_refs(struct rev_info *revs, unsigned flags,
 	for_each(handle_one_ref, &cb);
 }
 
+static void handle_connected_refs(struct rev_info *revs, unsigned flags,
+		int (*for_each)(each_ref_fn, void *))
+{
+	struct all_refs_cb cb;
+	cb.all_revs = revs;
+	cb.all_flags = flags;
+	for_each(handle_one_connected_ref, &cb);
+}
+
 static void handle_one_reflog_commit(unsigned char *sha1, void *cb_data)
 {
 	struct all_refs_cb *cb = cb_data;
@@ -1352,6 +1386,10 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 				handle_refs(revs, flags, for_each_remote_ref);
 				continue;
 			}
+			if (!strcmp(arg, "--bouquet")) {
+				handle_connected_refs(revs, flags, for_each_ref);
+				continue;
+			}
 			if (!strcmp(arg, "--reflog")) {
 				handle_reflog(revs, flags);
 				continue;
-- 
1.6.5.3