Refactor "tracking statistics" code used by "git checkout"

People seem to like "Your branch is ahead by N commit" report made by
"git checkout", but the interface into the statistics function was a bit
clunky.  This splits the function into three parts:

 * The core "commit counting" function that takes "struct branch" and
   returns number of commits to show if we are ahead, behind or forked;

 * Convenience "stat formating" function that takes "struct branch" and
   formats the report into a given strbuf, using the above function;

 * "checkout" specific function that takes "branch_info" (type that is
   internal to checkout implementation), calls the above function and
   print the formatted result.

in the hope that the former two can be more easily reusable.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/remote.h b/remote.h
index 8eed87ba5a..091b1d041f 100644
--- a/remote.h
+++ b/remote.h
@@ -129,4 +129,8 @@ enum match_refs_flags {
 	MATCH_REFS_MIRROR	= (1 << 1),
 };
 
+/* Reporting of tracking info */
+int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs);
+int format_tracking_info(struct branch *branch, struct strbuf *sb);
+
 #endif