UUID: add nil value for UUIDs

Add `BLI_uuid_nil()` that returns the nil UUID (used to indicate "not
set") and `BLI_uuid_is_nil(uuid)` to do an equality test with the nil
value.

1 files changed, 11 insertions, 0 deletions

diff --git a/source/blender/blenlib/intern/uuid.cc b/source/blender/blenlib/intern/uuid.cc
index 5d4f7e1a520..f5edb356acc 100644
--- a/source/blender/blenlib/intern/uuid.cc
+++ b/source/blender/blenlib/intern/uuid.cc
@@ -78,6 +78,17 @@ UUID BLI_uuid_generate_random()
   return uuid;
 }
 
+UUID BLI_uuid_nil(void)
+{
+  const UUID nil = {0, 0, 0, 0, 0, 0};
+  return nil;
+}
+
+bool BLI_uuid_is_nil(UUID uuid)
+{
+  return BLI_uuid_equal(BLI_uuid_nil(), uuid);
+}
+
 bool BLI_uuid_equal(const UUID uuid1, const UUID uuid2)
 {
   return std::memcmp(&uuid1, &uuid2, sizeof(uuid1)) == 0;