[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, 9 insertions, 3 deletions

diff --git a/diff-tree.c b/diff-tree.c
index a29c738..2075715 100644
--- a/diff-tree.c
+++ b/diff-tree.c
@@ -18,6 +18,7 @@ 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 const char *header = NULL;
 static const char *header_prefix = "";
 static enum cmit_fmt commit_format = CMIT_FMT_RAW;
@@ -272,9 +273,10 @@ static int call_diff_flush(void)
 		     detect_rename, diff_score_opt,
 		     pickaxe, pickaxe_opts,
 		     diff_break_opt,
-		     orderfile);
+		     orderfile,
+		     diff_filter);
 	if (diff_queue_is_empty()) {
-		diff_flush(DIFF_FORMAT_NO_OUTPUT, 0);
+		diff_flush(DIFF_FORMAT_NO_OUTPUT);
 		return 0;
 	}
 	if (header) {
@@ -285,7 +287,7 @@ static int call_diff_flush(void)
 		printf(fmt, header, 0);
 		header = NULL;
 	}
-	diff_flush(diff_output_format, 1);
+	diff_flush(diff_output_format);
 	return 1;
 }
 
@@ -468,6 +470,10 @@ int main(int argc, const char **argv)
 			orderfile = arg + 2;
 			continue;
 		}
+		if (!strncmp(arg, "--diff-filter=", 14)) {
+			diff_filter = arg + 14;
+			continue;
+		}
 		if (!strcmp(arg, "--pickaxe-all")) {
 			pickaxe_opts = DIFF_PICKAXE_ALL;
 			continue;