[PATCH] Add --diff-filter= output restriction to diff-* family.

This is a halfway between debugging aid and a helper to write an
ultra-smart merge scripts.  The new option takes a string that
consists of a list of "status" letters, and limits the diff
output to only those classes of changes, with two exceptions:

 - A broken pair (aka "complete rewrite"), does not match D
   (deleted) or N (created).  Use B to look for them.

 - The letter "A" in the diff-filter string does not match
   anything itself, but causes the entire diff that contains
   selected patches to be output (this behaviour is similar to
   that of --pickaxe-all for the -S option).

For example,

    $ git-rev-list HEAD |
      git-diff-tree --stdin -s -v -B -C --diff-filter=BCR

shows a list of commits that have complete rewrite, copy, or
rename.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/diff-stages.c b/diff-stages.c
index 0090ac00b..78729d781 100644
--- a/diff-stages.c
+++ b/diff-stages.c
@@ -13,6 +13,7 @@ static const char *pickaxe = NULL;
 static int pickaxe_opts = 0;
 static int diff_break_opt = -1;
 static const char *orderfile = NULL;
+static const char *diff_filter = NULL;
 
 static char *diff_stages_usage =
 "git-diff-stages [-p] [-r] [-z] [-M] [-C] [-R] [-S<string>] [-O<orderfile>] <stage1> <stage2> [<path>...]";
@@ -50,6 +51,8 @@ int main(int ac, const char **av)
 			pickaxe = arg + 2;
 		else if (!strncmp(arg, "-O", 2))
 			orderfile = arg + 2;
+		else if (!strncmp(arg, "--diff-filter=", 14))
+			diff_filter = arg + 14;
 		else if (!strcmp(arg, "--pickaxe-all"))
 			pickaxe_opts = DIFF_PICKAXE_ALL;
 		else
@@ -106,7 +109,8 @@ int main(int ac, const char **av)
 		     detect_rename, diff_score_opt,
 		     pickaxe, pickaxe_opts,
 		     diff_break_opt,
-		     orderfile);
-	diff_flush(diff_output_format, 1);
+		     orderfile,
+		     diff_filter);
+	diff_flush(diff_output_format);
 	return 0;
 }