Bug 1981341 - Add referenceTarget and shadowRootReferenceTarget attributes. r=webidl,emilio,hsivonen

Allows setting referenceTarget when creating shadow roots declaratively or programatically, and also getting the referenceTarget value for a shadow root.

Differential Revision: https://phabricator.services.mozilla.com/D260140

Author: alice

dom/base/Element.cpp

@@ -1349,16 +1349,19 @@ already_AddRefed<ShadowRoot> Element::AttachShadow(const ShadowRootInit& aInit,
     OwnerDoc()->ReportShadowDOMUsage();
   }
 
+  const nsString& referenceTarget = aInit.mReferenceTarget.WasPassed()
+                                        ? aInit.mReferenceTarget.Value()
+                                        : VoidString();
   return AttachShadowWithoutNameChecks(
       aInit.mMode, DelegatesFocus(aInit.mDelegatesFocus), aInit.mSlotAssignment,
       ShadowRootClonable(aInit.mClonable),
-      ShadowRootSerializable(aInit.mSerializable));
+      ShadowRootSerializable(aInit.mSerializable), referenceTarget);
 }
 
 already_AddRefed<ShadowRoot> Element::AttachShadowWithoutNameChecks(
     ShadowRootMode aMode, DelegatesFocus aDelegatesFocus,
     SlotAssignmentMode aSlotAssignment, ShadowRootClonable aClonable,
-    ShadowRootSerializable aSerializable) {
+    ShadowRootSerializable aSerializable, const nsAString& aReferenceTarget) {
   nsAutoScriptBlocker scriptBlocker;
 
   auto* nim = mNodeInfo->NodeInfoManager();
@@ -1385,6 +1388,7 @@ already_AddRefed<ShadowRoot> Element::AttachShadowWithoutNameChecks(
   RefPtr<ShadowRoot> shadowRoot = new (nim)
       ShadowRoot(this, aMode, aDelegatesFocus, aSlotAssignment, aClonable,
                  aSerializable, ShadowRootDeclarative::No, nodeInfo.forget());
+  shadowRoot->SetReferenceTarget(aReferenceTarget);
 
   if (NodeOrAncestorHasDirAuto()) {
     shadowRoot->SetAncestorHasDirAuto();

dom/base/Element.h

@@ -1478,7 +1478,8 @@ class Element : public FragmentOrElement {
       ShadowRootMode aMode, DelegatesFocus = DelegatesFocus::No,
       SlotAssignmentMode aSlotAssignmentMode = SlotAssignmentMode::Named,
       ShadowRootClonable aClonable = ShadowRootClonable::No,
-      ShadowRootSerializable aSerializable = ShadowRootSerializable::No);
+      ShadowRootSerializable aSerializable = ShadowRootSerializable::No,
+      const nsAString& aReferenceTarget = EmptyString());
 
   // Attach UA Shadow Root if it is not attached.
   enum class NotifyUAWidgetSetup : bool { No, Yes };

dom/base/ShadowRoot.cpp

@@ -70,7 +70,8 @@ ShadowRoot::ShadowRoot(Element* aElement, ShadowRootMode aMode,
       mIsAvailableToElementInternals(false),
       mIsDeclarative(aDeclarative),
       mIsClonable(aIsClonable),
-      mIsSerializable(aIsSerializable) {
+      mIsSerializable(aIsSerializable),
+      mReferenceTarget(nsGkAtoms::_empty) {
   // nsINode.h relies on this.
   MOZ_ASSERT(static_cast<nsINode*>(this) == reinterpret_cast<nsINode*>(this));
   MOZ_ASSERT(static_cast<nsIContent*>(this) ==
@@ -936,3 +937,7 @@ void ShadowRoot::GetHTML(const GetHTMLOptions& aOptions, nsAString& aResult) {
       this, true, aResult, aOptions.mSerializableShadowRoots,
       aOptions.mShadowRoots);
 }
+void ShadowRoot::SetReferenceTarget(RefPtr<nsAtom> aTarget) {
+  MOZ_ASSERT(aTarget);
+  mReferenceTarget = std::move(aTarget);
+}

dom/base/ShadowRoot.h

@@ -275,6 +275,19 @@ class ShadowRoot final : public DocumentFragment, public DocumentOrShadowRoot {
 
   void GetHTML(const GetHTMLOptions& aOptions, nsAString& aResult);
 
+  void GetReferenceTarget(nsAString& aResult) const {
+    mReferenceTarget->ToString(aResult);
+  }
+  nsAtom* ReferenceTarget() const { return mReferenceTarget; }
+  void SetReferenceTarget(const nsAString& aValue) {
+    SetReferenceTarget(NS_Atomize(aValue));
+  }
+  void SetReferenceTarget(RefPtr<nsAtom> aTarget);
+  Element* GetReferenceTargetElement() const {
+    return mReferenceTarget->IsEmpty() ? nullptr
+                                       : GetElementById(mReferenceTarget);
+  }
+
  protected:
   // FIXME(emilio): This will need to become more fine-grained.
   void ApplicableRulesChanged();
@@ -321,6 +334,8 @@ class ShadowRoot final : public DocumentFragment, public DocumentOrShadowRoot {
   // https://dom.spec.whatwg.org/#shadowroot-serializable
   const IsSerializable mIsSerializable;
 
+  RefPtr<nsAtom> mReferenceTarget;
+
   nsresult Clone(dom::NodeInfo*, nsINode** aResult) const override;
 };
 

dom/base/nsContentUtils.cpp

@@ -12385,11 +12385,10 @@ int32_t nsContentUtils::CompareTreePosition(const nsINode* aNode1,
   return static_cast<int32_t>(static_cast<int64_t>(*index1) - *index2);
 }
 
-nsIContent* nsContentUtils::AttachDeclarativeShadowRoot(nsIContent* aHost,
-                                                        ShadowRootMode aMode,
-                                                        bool aIsClonable,
-                                                        bool aIsSerializable,
-                                                        bool aDelegatesFocus) {
+nsIContent* nsContentUtils::AttachDeclarativeShadowRoot(
+    nsIContent* aHost, ShadowRootMode aMode, bool aIsClonable,
+    bool aIsSerializable, bool aDelegatesFocus,
+    const nsAString& aReferenceTarget) {
   RefPtr<Element> host = mozilla::dom::Element::FromNodeOrNull(aHost);
   if (!host || host->GetShadowRoot()) {
     // https://html.spec.whatwg.org/#parsing-main-inhead:shadow-host
@@ -12409,6 +12408,7 @@ nsIContent* nsContentUtils::AttachDeclarativeShadowRoot(nsIContent* aHost,
         nsGenericHTMLFormControlElement::ShadowRootDeclarative::Yes);
     // https://html.spec.whatwg.org/#parsing-main-inhead:available-to-element-internals
     shadowRoot->SetAvailableToElementInternals();
+    shadowRoot->SetReferenceTarget(aReferenceTarget);
   }
   return shadowRoot;
 }

dom/base/nsContentUtils.h

@@ -3562,7 +3562,7 @@ class nsContentUtils {
   MOZ_CAN_RUN_SCRIPT_BOUNDARY
   static nsIContent* AttachDeclarativeShadowRoot(
       nsIContent* aHost, mozilla::dom::ShadowRootMode aMode, bool aIsClonable,
-      bool aIsSerializable, bool aDelegatesFocus);
+      bool aIsSerializable, bool aDelegatesFocus, const nsAString&);
 
   static bool NavigationMustBeAReplace(nsIURI& aURI, const Document& aDocument);
 

dom/base/nsINode.cpp

@@ -3960,6 +3960,8 @@ already_AddRefed<nsINode> nsINode::CloneAndAdopt(
         return nullptr;
       }
       newShadowRoot->SetIsDeclarative(originalShadowRoot->IsDeclarative());
+      nsAtom* referenceTarget = originalShadowRoot->ReferenceTarget();
+      newShadowRoot->SetReferenceTarget(referenceTarget);
 
       for (nsIContent* origChild = originalShadowRoot->GetFirstChild();
            origChild; origChild = origChild->GetNextSibling()) {

dom/html/HTMLTemplateElement.h

@@ -72,6 +72,13 @@ class HTMLTemplateElement final : public nsGenericHTMLElement {
     SetHTMLBoolAttr(nsGkAtoms::shadowrootserializable, aValue, aRv);
   }
 
+  void GetShadowRootReferenceTarget(nsAString& aResult) const {
+    GetHTMLAttr(nsGkAtoms::shadowrootreferencetarget, aResult);
+  }
+  void SetShadowRootReferenceTarget(const nsAString& aValue, ErrorResult& aRv) {
+    SetHTMLAttr(nsGkAtoms::shadowrootreferencetarget, aValue);
+  }
+
   void SetHTML(const nsAString& aInnerHTML, const SetHTMLOptions& aOptions,
                ErrorResult& aError) final;
 

dom/webidl/Element.webidl

@@ -279,6 +279,10 @@ dictionary ShadowRootInit {
   SlotAssignmentMode slotAssignment = "named";
   boolean clonable = false;
   boolean serializable = false;
+
+  // https://github.com/whatwg/dom/pull/1353
+  [Pref="dom.shadowdom.referenceTarget.enabled"]
+  DOMString referenceTarget;
 };
 
 // https://dom.spec.whatwg.org/#element

dom/webidl/HTMLTemplateElement.webidl

@@ -22,4 +22,6 @@ interface HTMLTemplateElement : HTMLElement {
   attribute boolean shadowRootClonable;
   [CEReactions, SetterThrows]
   attribute boolean shadowRootSerializable;
+  [CEReactions, SetterThrows, Pref="dom.shadowdom.referenceTarget.enabled"]
+  attribute DOMString shadowRootReferenceTarget;
 };