Implement ShadowRoot.clonable attribute (#34514)

* Implement ShadowRoot clonable attribute

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Update WPT expectations

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* Update WPT expectations

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* ./mach test-tidy fixes

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

* fix clippy warnings

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

---------

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

components/script/dom/element.rs

@@ -507,8 +507,10 @@ impl Element {
     /// <https://dom.spec.whatwg.org/#dom-element-attachshadow>
     pub fn attach_shadow(
         &self,
+        // TODO: remove is_ua_widget argument
         is_ua_widget: IsUserAgentWidget,
         mode: ShadowRootMode,
+        clonable: bool,
     ) -> Fallible<DomRoot<ShadowRoot>> {
         // Step 1.
         if self.namespace != ns!(html) {
@@ -546,7 +548,7 @@ impl Element {
         }
 
         // Steps 4, 5 and 6.
-        let shadow_root = ShadowRoot::new(self, &self.node.owner_doc(), mode);
+        let shadow_root = ShadowRoot::new(self, &self.node.owner_doc(), mode, clonable);
         self.ensure_rare_data().shadow_root = Some(Dom::from_ref(&*shadow_root));
         shadow_root
             .upcast::<Node>()
@@ -3034,7 +3036,7 @@ impl ElementMethods<crate::DomTypeHolder> for Element {
     fn AttachShadow(&self, init: &ShadowRootInit) -> Fallible<DomRoot<ShadowRoot>> {
         // Step 1. Run attach a shadow root with this, init["mode"], init["clonable"], init["serializable"],
         // init["delegatesFocus"], and init["slotAssignment"].
-        let shadow_root = self.attach_shadow(IsUserAgentWidget::No, init.mode)?;
+        let shadow_root = self.attach_shadow(IsUserAgentWidget::No, init.mode, init.clonable)?;
 
         // Step 2. Return this’s shadow root.
         Ok(shadow_root)

components/script/dom/htmlmediaelement.rs

@@ -1910,7 +1910,7 @@ impl HTMLMediaElement {
             return;
         }
         let shadow_root = element
-            .attach_shadow(IsUserAgentWidget::Yes, ShadowRootMode::Closed)
+            .attach_shadow(IsUserAgentWidget::Yes, ShadowRootMode::Closed, false)
             .unwrap();
         let document = document_from_node(self);
         let script = HTMLScriptElement::new(

components/script/dom/node.rs

@@ -98,7 +98,7 @@ 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::shadowroot::{IsUserAgentWidget, LayoutShadowRootHelpers, ShadowRoot};
 use crate::dom::stylesheetlist::StyleSheetListOwner;
 use crate::dom::svgsvgelement::{LayoutSVGSVGElementHelpers, SVGSVGElement};
 use crate::dom::text::Text;
@@ -2247,13 +2247,13 @@ impl Node {
         clone_children: CloneChildrenFlag,
         can_gc: CanGc,
     ) -> DomRoot<Node> {
-        // Step 1.
+        // Step 1. If document is not given, let document be node’s node document.
         let document = match maybe_doc {
             Some(doc) => DomRoot::from_ref(doc),
             None => node.owner_doc(),
         };
 
-        // Step 2.
+        // Step 2. / Step 3.
         // XXXabinader: clone() for each node as trait?
         let copy: DomRoot<Node> = match node.type_id() {
             NodeTypeId::DocumentType => {
@@ -2337,14 +2337,15 @@ impl Node {
             },
         };
 
-        // Step 3.
+        // Step 4. Set copy’s node document and document to copy, if copy is a document,
+        // and set copy’s node document to document otherwise.
         let document = match copy.downcast::<Document>() {
             Some(doc) => DomRoot::from_ref(doc),
             None => DomRoot::from_ref(&*document),
         };
         assert!(copy.owner_doc() == document);
 
-        // Step 4 (some data already copied in step 2).
+        // TODO: The spec tells us to do this in step 3.
         match node.type_id() {
             NodeTypeId::Document(_) => {
                 let node_doc = node.downcast::<Document>().unwrap();
@@ -2370,10 +2371,12 @@ impl Node {
             _ => (),
         }
 
-        // Step 5: cloning steps.
+        // Step 5: Run any cloning steps defined for node in other applicable specifications and pass copy,
+        // node, document, and the clone children flag if set, as parameters.
         vtable_for(node).cloning_steps(&copy, maybe_doc, clone_children);
 
-        // Step 6.
+        // Step 6. If the clone children flag is set, then for each child child of node, in tree order: append the
+        // result of cloning child with document and the clone children flag set, to copy.
         if clone_children == CloneChildrenFlag::CloneChildren {
             for child in node.children() {
                 let child_copy = Node::clone(&child, Some(&document), clone_children, can_gc);
@@ -2381,7 +2384,43 @@ impl Node {
             }
         }
 
-        // Step 7.
+        // Step 7. If node is a shadow host whose shadow root’s clonable is true:
+        // NOTE: Only elements can be shadow hosts
+        if matches!(node.type_id(), NodeTypeId::Element(_)) {
+            let node_elem = node.downcast::<Element>().unwrap();
+            let copy_elem = copy.downcast::<Element>().unwrap();
+
+            if let Some(shadow_root) = node_elem.shadow_root().filter(|r| r.Clonable()) {
+                // Step 7.1 Assert: copy is not a shadow host.
+                assert!(!copy_elem.is_shadow_host());
+
+                // Step 7.2 Run attach a shadow root with copy, node’s shadow root’s mode, true,
+                // node’s shadow root’s serializable, node’s shadow root’s delegates focus,
+                // and node’s shadow root’s slot assignment.
+                let copy_shadow_root =
+                    copy_elem.attach_shadow(IsUserAgentWidget::No, shadow_root.Mode(), true)
+                    .expect("placement of attached shadow root must be valid, as this is a copy of an existing one");
+
+                // TODO: Step 7.3 Set copy’s shadow root’s declarative to node’s shadow root’s declarative.
+
+                // Step 7.4 For each child child of node’s shadow root, in tree order: append the result of
+                // cloning child with document and the clone children flag set, to copy’s shadow root.
+                for child in shadow_root.upcast::<Node>().children() {
+                    let child_copy = Node::clone(
+                        &child,
+                        Some(&document),
+                        CloneChildrenFlag::CloneChildren,
+                        can_gc,
+                    );
+
+                    // TODO: Should we handle the error case here and in step 6?
+                    let _inserted_node =
+                        Node::pre_insert(&child_copy, copy_shadow_root.upcast::<Node>(), None);
+                }
+            }
+        }
+
+        // Step 8. Return copy.
         copy
     }
 

components/script/dom/shadowroot.rs

@@ -55,11 +55,19 @@ pub struct ShadowRoot {
 
     /// <https://dom.spec.whatwg.org/#dom-shadowroot-mode>
     mode: ShadowRootMode,
+
+    /// <https://dom.spec.whatwg.org/#dom-shadowroot-clonable>
+    clonable: bool,
 }
 
 impl ShadowRoot {
     #[allow(crown::unrooted_must_root)]
-    fn new_inherited(host: &Element, document: &Document, mode: ShadowRootMode) -> ShadowRoot {
+    fn new_inherited(
+        host: &Element,
+        document: &Document,
+        mode: ShadowRootMode,
+        clonable: bool,
+    ) -> ShadowRoot {
         let document_fragment = DocumentFragment::new_inherited(document);
         let node = document_fragment.upcast::<Node>();
         node.set_flag(NodeFlags::IS_IN_SHADOW_TREE, true);
@@ -77,12 +85,18 @@ impl ShadowRoot {
             stylesheet_list: MutNullableDom::new(None),
             window: Dom::from_ref(document.window()),
             mode,
+            clonable,
         }
     }
 
-    pub fn new(host: &Element, document: &Document, mode: ShadowRootMode) -> DomRoot<ShadowRoot> {
+    pub fn new(
+        host: &Element,
+        document: &Document,
+        mode: ShadowRootMode,
+        clonable: bool,
+    ) -> DomRoot<ShadowRoot> {
         reflect_dom_object(
-            Box::new(ShadowRoot::new_inherited(host, document, mode)),
+            Box::new(ShadowRoot::new_inherited(host, document, mode, clonable)),
             document.window(),
         )
     }
@@ -238,6 +252,11 @@ impl ShadowRootMethods<crate::DomTypeHolder> for ShadowRoot {
         self.mode
     }
 
+    /// <https://dom.spec.whatwg.org/#dom-shadowroot-clonable>
+    fn Clonable(&self) -> bool {
+        self.clonable
+    }
+
     /// <https://dom.spec.whatwg.org/#dom-shadowroot-host>
     fn Host(&self) -> DomRoot<Element> {
         let host = self.host.get();

components/script/dom/webidls/Element.webidl

@@ -91,7 +91,7 @@ dictionary ShadowRootInit {
   required ShadowRootMode mode;
   // boolean delegatesFocus = false;
   // SlotAssignmentMode slotAssignment = "named";
-  // boolean clonable = false;
+  boolean clonable = false;
   // boolean serializable = false;
 };
 

components/script/dom/webidls/ShadowRoot.webidl

@@ -9,9 +9,15 @@
 [Exposed=Window]
 interface ShadowRoot : DocumentFragment {
   readonly attribute ShadowRootMode mode;
+  // readonly attribute boolean delegatesFocus;
+  // readonly attribute SlotAssignmentMode slotAssignment;
+  readonly attribute boolean clonable;
+  // readonly attribute boolean serializable;
   readonly attribute Element host;
+  // attribute EventHandler onslotchange;
 };
 
+
 enum ShadowRootMode { "open", "closed"};
 // enum SlotAssignmentMode { "manual", "named" };
 

tests/wpt/meta/dom/idlharness.window.js.ini

@@ -694,9 +694,6 @@
   [AbortSignal interface: calling any(sequence<AbortSignal>) on new AbortController().signal with too few arguments must throw TypeError]
     expected: FAIL
 
-  [ShadowRoot interface: attribute clonable]
-    expected: FAIL
-
   [Document interface: operation prepend((Node or TrustedScript or DOMString)...)]
     expected: FAIL
 

tests/wpt/meta/shadow-dom/shadow-root-clonable.html.ini

@@ -1,13 +1,4 @@
 [shadow-root-clonable.html]
-  [attachShadow with clonable: true]
-    expected: FAIL
-
-  [attachShadow with clonable: false]
-    expected: FAIL
-
-  [attachShadow with clonable: undefined]
-    expected: FAIL
-
   [declarative shadow roots do *not* get clonable: true automatically]
     expected: FAIL