1 files changed, 61 insertions, 0 deletions
diff --git a/servo/components/style/gecko_bindings/sugar/ownership.rs b/servo/components/style/gecko_bindings/sugar/ownership.rs
new file mode 100644
index 0000000000..31b512cf1e
--- /dev/null
+++ b/servo/components/style/gecko_bindings/sugar/ownership.rs
@@ -0,0 +1,61 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//! Helpers for different FFI pointer kinds that Gecko's FFI layer uses.
+
+use crate::gecko_bindings::structs::root::mozilla::detail::CopyablePtr;
+use servo_arc::Arc;
+use std::marker::PhantomData;
+use std::ops::{Deref, DerefMut};
+use std::ptr;
+
+/// Gecko-FFI-safe Arc (T is an ArcInner).
+///
+/// This can be null.
+///
+/// Leaks on drop. Please don't drop this.
+#[repr(C)]
+pub struct Strong<GeckoType> {
+    ptr: *const GeckoType,
+    _marker: PhantomData<GeckoType>,
+}
+
+impl<T> From<Arc<T>> for Strong<T> {
+    fn from(arc: Arc<T>) -> Self {
+        Self {
+            ptr: Arc::into_raw(arc),
+            _marker: PhantomData,
+        }
+    }
+}
+
+impl<GeckoType> Strong<GeckoType> {
+    #[inline]
+    /// Returns whether this reference is null.
+    pub fn is_null(&self) -> bool {
+        self.ptr.is_null()
+    }
+
+    #[inline]
+    /// Returns a null pointer
+    pub fn null() -> Self {
+        Self {
+            ptr: ptr::null(),
+            _marker: PhantomData,
+        }
+    }
+}
+
+impl<T> Deref for CopyablePtr<T> {
+    type Target = T;
+    fn deref(&self) -> &Self::Target {
+        &self.mPtr
+    }
+}
+
+impl<T> DerefMut for CopyablePtr<T> {
+    fn deref_mut<'a>(&'a mut self) -> &'a mut T {
+        &mut self.mPtr
+    }
+}