1 files changed, 30 insertions, 0 deletions
diff --git a/components/script/dom/macros.rs b/components/script/dom/macros.rs
index a566fee4fb6..0fb51c7d8fd 100644
--- a/components/script/dom/macros.rs
+++ b/components/script/dom/macros.rs
@@ -632,3 +632,33 @@ macro_rules! handle_potential_webgl_error {
         handle_potential_webgl_error!($context, $call, ());
     };
 }
+
+macro_rules! impl_rare_data (
+    ($type:ty) => (
+        fn init_rare_data(&self) {
+            let mut rare_data = self.rare_data.borrow_mut();
+            if rare_data.is_none() {
+                *rare_data = Some(Default::default());
+            }
+        }
+
+        fn rare_data(&self) -> Ref<Option<Box<$type>>> {
+            self.init_rare_data();
+            self.rare_data.borrow()
+        }
+
+        fn rare_data_mut(&self) -> RefMut<Option<Box<$type>>> {
+            self.init_rare_data();
+            self.rare_data.borrow_mut()
+        }
+
+        #[allow(unsafe_code)]
+        fn rare_data_for_layout(&self) -> &Option<Box<$type>> {
+            let mut rare_data = self.rare_data.borrow_mut_for_layout();
+            if rare_data.is_none() {
+                *rare_data = Some(Default::default());
+            }
+            unsafe { self.rare_data.borrow_for_layout() }
+        }
+    );
+);