Introduce NodeRareData and ElementRareData

4 files changed, 46 insertions, 17 deletions

diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 9ba5f7c21a2..ce4a3ac5268 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -76,6 +76,7 @@ use crate::dom::node::{BindContext, NodeDamage, NodeFlags, UnbindContext};
 use crate::dom::node::{ChildrenMutation, LayoutNodeHelpers, Node};
 use crate::dom::nodelist::NodeList;
 use crate::dom::promise::Promise;
+use crate::dom::raredata::ElementRareData;
 use crate::dom::servoparser::ServoParser;
 use crate::dom::shadowroot::ShadowRoot;
 use crate::dom::text::Text;
@@ -172,10 +173,7 @@ pub struct Element {
     custom_element_definition: DomRefCell<Option<Rc<CustomElementDefinition>>>,
     /// <https://dom.spec.whatwg.org/#concept-element-custom-element-state>
     custom_element_state: Cell<CustomElementState>,
-    /// https://dom.spec.whatwg.org/#dom-element-shadowroot
-    /// XXX This is currently not exposed to web content. Only for
-    ///     internal use.
-    shadow_root: MutNullableDom<ShadowRoot>,
+    rare_data: Box<ElementRareData>,
 }
 
 impl fmt::Debug for Element {
@@ -310,7 +308,7 @@ impl Element {
             custom_element_reaction_queue: Default::default(),
             custom_element_definition: Default::default(),
             custom_element_state: Cell::new(CustomElementState::Uncustomized),
-            shadow_root: Default::default(),
+            rare_data: Default::default(),
         }
     }
 
@@ -452,7 +450,7 @@ impl Element {
     }
 
     pub fn is_shadow_host(&self) -> bool {
-        self.shadow_root.get().is_some()
+        self.rare_data.shadow_root.get().is_some()
     }
 
     /// https://dom.spec.whatwg.org/#dom-element-attachshadow
@@ -496,6 +494,7 @@ impl Element {
 
         // Steps 4, 5 and 6.
         let shadow_root = self
+            .rare_data
             .shadow_root
             .or_init(|| ShadowRoot::new(self, &*self.node.owner_doc()));
 
@@ -1070,7 +1069,10 @@ impl LayoutElementHelpers for LayoutDom<Element> {
     #[inline]
     #[allow(unsafe_code)]
     unsafe fn get_shadow_root_for_layout(&self) -> Option<LayoutDom<ShadowRoot>> {
-        (*self.unsafe_get()).shadow_root.get_inner_as_layout()
+        (*self.unsafe_get())
+            .rare_data
+            .shadow_root
+            .get_inner_as_layout()
     }
 }
 
@@ -2847,7 +2849,7 @@ impl VirtualMethods for Element {
 
         let doc = document_from_node(self);
 
-        if let Some(shadow_root) = self.shadow_root.get() {
+        if let Some(shadow_root) = self.rare_data.shadow_root.get() {
             doc.unregister_shadow_root(&shadow_root);
             let shadow_root = shadow_root.upcast::<Node>();
             shadow_root.set_flag(NodeFlags::IS_CONNECTED, false);
diff --git a/components/script/dom/mod.rs b/components/script/dom/mod.rs
index 15d3ba34a23..776d20299c1 100644
--- a/components/script/dom/mod.rs
+++ b/components/script/dom/mod.rs
@@ -443,6 +443,7 @@ pub mod promisenativehandler;
 pub mod promiserejectionevent;
 pub mod radionodelist;
 pub mod range;
+pub mod raredata;
 pub mod request;
 pub mod response;
 pub mod rtcicecandidate;
diff --git a/components/script/dom/node.rs b/components/script/dom/node.rs
index 8070481045a..f8b6de5cb24 100644
--- a/components/script/dom/node.rs
+++ b/components/script/dom/node.rs
@@ -53,6 +53,7 @@ use crate::dom::mutationobserver::{Mutation, MutationObserver, RegisteredObserve
 use crate::dom::nodelist::NodeList;
 use crate::dom::processinginstruction::ProcessingInstruction;
 use crate::dom::range::WeakRangeVec;
+use crate::dom::raredata::NodeRareData;
 use crate::dom::shadowroot::{LayoutShadowRootHelpers, ShadowRoot};
 use crate::dom::stylesheetlist::StyleSheetListOwner;
 use crate::dom::svgsvgelement::{LayoutSVGSVGElementHelpers, SVGSVGElement};
@@ -124,10 +125,8 @@ pub struct Node {
     /// The document that this node belongs to.
     owner_doc: MutNullableDom<Document>,
 
-    /// The shadow root this node belongs to.
-    /// This is None if the node is not in a shadow tree or
-    /// if it is a ShadowRoot.
-    owner_shadow_root: MutNullableDom<ShadowRoot>,
+    /// Rare node data.
+    rare_data: Box<NodeRareData>,
 
     /// The live list of children return by .childNodes.
     child_list: MutNullableDom<NodeList>,
@@ -937,11 +936,11 @@ impl Node {
         if let Some(ref shadow_root) = self.downcast::<ShadowRoot>() {
             return Some(DomRoot::from_ref(shadow_root));
         }
-        self.owner_shadow_root.get()
+        self.rare_data.owner_shadow_root.get()
     }
 
     pub fn set_owner_shadow_root(&self, shadow_root: &ShadowRoot) {
-        self.owner_shadow_root.set(Some(shadow_root));
+        self.rare_data.owner_shadow_root.set(Some(shadow_root));
     }
 
     pub fn is_in_html_doc(&self) -> bool {
@@ -1272,7 +1271,10 @@ impl LayoutNodeHelpers for LayoutDom<Node> {
     #[inline]
     #[allow(unsafe_code)]
     unsafe fn owner_shadow_root_for_layout(&self) -> Option<LayoutDom<ShadowRoot>> {
-        (*self.unsafe_get()).owner_shadow_root.get_inner_as_layout()
+        (*self.unsafe_get())
+            .rare_data
+            .owner_shadow_root
+            .get_inner_as_layout()
     }
 
     #[inline]
@@ -1641,7 +1643,7 @@ impl Node {
             next_sibling: Default::default(),
             prev_sibling: Default::default(),
             owner_doc: MutNullableDom::new(doc),
-            owner_shadow_root: Default::default(),
+            rare_data: Default::default(),
             child_list: Default::default(),
             children_count: Cell::new(0u32),
             flags: Cell::new(flags),
@@ -2280,7 +2282,7 @@ impl NodeMethods for Node {
     // https://dom.spec.whatwg.org/#dom-node-getrootnode
     fn GetRootNode(&self, options: &GetRootNodeOptions) -> DomRoot<Node> {
         if options.composed {
-            if let Some(shadow_root) = self.owner_shadow_root.get() {
+            if let Some(shadow_root) = self.rare_data.owner_shadow_root.get() {
                 // shadow-including root.
                 return shadow_root.Host().upcast::<Node>().GetRootNode(options);
             }
diff --git a/components/script/dom/raredata.rs b/components/script/dom/raredata.rs
new file mode 100644
index 00000000000..65b47a40e41
--- /dev/null
+++ b/components/script/dom/raredata.rs
@@ -0,0 +1,24 @@
+/* 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/. */
+
+use crate::dom::bindings::root::MutNullableDom;
+use crate::dom::shadowroot::ShadowRoot;
+
+#[derive(Default, JSTraceable, MallocSizeOf)]
+#[must_root]
+pub struct NodeRareData {
+    /// The shadow root the node belongs to.
+    /// This is None if the node is not in a shadow tree or
+    /// if it is a ShadowRoot.
+    pub owner_shadow_root: MutNullableDom<ShadowRoot>,
+}
+
+#[derive(Default, JSTraceable, MallocSizeOf)]
+#[must_root]
+pub struct ElementRareData {
+    /// https://dom.spec.whatwg.org/#dom-element-shadowroot
+    /// XXX This is currently not exposed to web content. Only for
+    ///     internal use.
+    pub shadow_root: MutNullableDom<ShadowRoot>,
+}