Add '...' operator for revisions

'A...B' is a shortcut for 'A B --not $(git-merge-base --all A B)'.
This XOR-like operation is called symmetric difference in set
theory.

The symbol '...' has been chosen because it's rather similar to the
existing '..' operator and the somewhat more natural caret ('^') is
already taken.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 39 insertions, 9 deletions

diff --git a/revision.c b/revision.c
index b963f2adfd..9eb0b6da92 100644
--- a/revision.c
+++ b/revision.c
@@ -536,6 +536,18 @@ void init_revisions(struct rev_info *revs)
 	diff_setup(&revs->diffopt);
 }
 
+static void add_pending_commit_list(struct rev_info *revs,
+                                    struct commit_list *commit_list,
+                                    unsigned int flags)
+{
+	while (commit_list) {
+		struct object *object = &commit_list->item->object;
+		object->flags |= flags;
+		add_pending_object(revs, object, sha1_to_hex(object->sha1));
+		commit_list = commit_list->next;
+	}
+}
+
 /*
  * Parse revision information, filling in the "rev_info" structure,
  * and removing the used arguments from the argument list.
@@ -771,27 +783,45 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 			unsigned char from_sha1[20];
 			const char *next = dotdot + 2;
 			const char *this = arg;
+			int symmetric = *next == '.';
+			unsigned int flags_exclude = flags ^ UNINTERESTING;
+
 			*dotdot = 0;
+			next += symmetric;
+
 			if (!*next)
 				next = "HEAD";
 			if (dotdot == arg)
 				this = "HEAD";
 			if (!get_sha1(this, from_sha1) &&
 			    !get_sha1(next, sha1)) {
-				struct object *exclude;
-				struct object *include;
-
-				exclude = get_reference(revs, this, from_sha1, flags ^ UNINTERESTING);
-				include = get_reference(revs, next, sha1, flags);
-				if (!exclude || !include)
-					die("Invalid revision range %s..%s", arg, next);
+				struct commit *a, *b;
+				struct commit_list *exclude;
+
+				a = lookup_commit_reference(from_sha1);
+				b = lookup_commit_reference(sha1);
+				if (!a || !b) {
+					die(symmetric ?
+					    "Invalid symmetric difference expression %s...%s" :
+					    "Invalid revision range %s..%s",
+					    arg, next);
+				}
 
 				if (!seen_dashdash) {
 					*dotdot = '.';
 					verify_non_filename(revs->prefix, arg);
 				}
-				add_pending_object(revs, exclude, this);
-				add_pending_object(revs, include, next);
+
+				if (symmetric) {
+					exclude = get_merge_bases_clean(a, b);
+					add_pending_commit_list(revs, exclude,
+					                        flags_exclude);
+					a->object.flags |= flags;
+				} else
+					a->object.flags |= flags_exclude;
+				b->object.flags |= flags;
+				add_pending_object(revs, &a->object, this);
+				add_pending_object(revs, &b->object, next);
 				continue;
 			}
 			*dotdot = '.';