Re: A note on merging conflicts..

[Rene Scharfe <rene.scharfe@lsrfire.ath.cx>]

On Sat, Jul 01, 2006 at 07:45:33PM -0400, Daniel Barkalow wrote:
> That is: (this only has the logic portion, and it's against master, so it 
> isn't actually a really working patch or anything; also, it doesn't handle 
> "--not a...b" correctly, whatever that should mean)

[concept patch snipped]

You mean something like the patch below?  It seems to work, but in my
unscientific tests it's significant slower than the version based on
get_merge_bases() (0.17s vs 0.05s for
"git-rev-list 89719209...262a6ef7 66ae0c77...ced9456a").  Did I do
something wrong?

You had no mark_parents_left_right() in your patch.  I added it because
otherwise it wouldn't remove any common commits.  Was this supposed to
work some other way?

We still need an automatic test case, and a better benchmark.

diff --git a/revision.c b/revision.c
index ebee05a..8c494ee 100644
--- a/revision.c
+++ b/revision.c
@@ -339,6 +339,20 @@ static void try_to_simplify_commit(struc
 		commit->object.flags |= TREECHANGE;
 }
 
+static void mark_parents_left_right(struct commit *commit)
+{
+	unsigned int flags = commit->object.flags & (RIGHT_HALF | LEFT_HALF);
+	struct commit_list *parents = commit->parents;
+
+	while (parents) {
+		struct commit *p = parents->item;
+		p->object.flags |= flags;
+		if (p->parents)
+			mark_parents_left_right(p);
+		parents = parents->next;
+	}
+}
+
 static void add_parents_to_list(struct rev_info *revs, struct commit *commit, struct commit_list **list)
 {
 	struct commit_list *parent = commit->parents;
@@ -347,6 +361,13 @@ static void add_parents_to_list(struct r
 		return;
 	commit->object.flags |= ADDED;
 
+	if (commit->object.flags & (RIGHT_HALF | LEFT_HALF)) {
+		if (commit->object.flags & RIGHT_HALF &&
+		    commit->object.flags & LEFT_HALF)
+			commit->object.flags |= UNINTERESTING;
+		mark_parents_left_right(commit);
+	}
+
 	/*
 	 * If the commit is uninteresting, don't try to
 	 * prune parents - we want the maximal uninteresting
@@ -772,7 +793,10 @@ int setup_revisions(int argc, const char
 			unsigned char from_sha1[20];
 			const char *next = dotdot + 2;
 			const char *this = arg;
+			int symmetric = *next == '.';
+
 			*dotdot = 0;
+			next += symmetric;
 			if (!*next)
 				next = "HEAD";
 			if (dotdot == arg)
@@ -782,8 +806,13 @@ int setup_revisions(int argc, const char
 				struct object *exclude;
 				struct object *include;
 
-				exclude = get_reference(revs, this, from_sha1, flags ^ UNINTERESTING);
-				include = get_reference(revs, next, sha1, flags);
+				if (symmetric) {
+					exclude = get_reference(revs, this, from_sha1, flags | LEFT_HALF);
+					include = get_reference(revs, next, sha1, flags | RIGHT_HALF);
+				} else {
+					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);
 
diff --git a/revision.h b/revision.h
index c010a08..0090232 100644
--- a/revision.h
+++ b/revision.h
@@ -9,6 +9,8 @@ #define TMP_MARK	(1u<<4) /* for isolated
 #define BOUNDARY	(1u<<5)
 #define BOUNDARY_SHOW	(1u<<6)
 #define ADDED		(1u<<7)	/* Parents already parsed and added? */
+#define RIGHT_HALF	(1u<<8)
+#define LEFT_HALF	(1u<<9)
 
 struct rev_info;
 struct log_info;