From 87b0ddb354191ff096b29c02de6b8814d418cb27 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Sat, 5 Nov 2022 17:06:19 +0100
Subject: [PATCH] LibWeb: Add DOM::Node::parent_or_shadow_host_element()

This will be used in style computation to inherit style across shadow
tree boundaries.
---
 Userland/Libraries/LibWeb/DOM/Node.cpp | 13 +++++++++++++
 Userland/Libraries/LibWeb/DOM/Node.h   |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/Userland/Libraries/LibWeb/DOM/Node.cpp b/Userland/Libraries/LibWeb/DOM/Node.cpp
index 57a756a109..d249c0b140 100644
--- a/Userland/Libraries/LibWeb/DOM/Node.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Node.cpp
@@ -872,6 +872,19 @@ ParentNode* Node::parent_or_shadow_host()
     return verify_cast<ParentNode>(parent());
 }
 
+Element* Node::parent_or_shadow_host_element()
+{
+    if (is<ShadowRoot>(*this))
+        return static_cast<ShadowRoot&>(*this).host();
+    if (!parent())
+        return nullptr;
+    if (is<Element>(*parent()))
+        return static_cast<Element*>(parent());
+    if (is<ShadowRoot>(*parent()))
+        return static_cast<ShadowRoot&>(*parent()).host();
+    return nullptr;
+}
+
 JS::NonnullGCPtr<NodeList> Node::child_nodes()
 {
     if (!m_child_nodes) {
diff --git a/Userland/Libraries/LibWeb/DOM/Node.h b/Userland/Libraries/LibWeb/DOM/Node.h
index 7e0dd8ec0b..a0dd4bda03 100644
--- a/Userland/Libraries/LibWeb/DOM/Node.h
+++ b/Userland/Libraries/LibWeb/DOM/Node.h
@@ -45,6 +45,9 @@ public:
     ParentNode* parent_or_shadow_host();
     ParentNode const* parent_or_shadow_host() const { return const_cast<Node*>(this)->parent_or_shadow_host(); }
 
+    Element* parent_or_shadow_host_element();
+    Element const* parent_or_shadow_host_element() const { return const_cast<Node*>(this)->parent_or_shadow_host_element(); }
+
     virtual ~Node();
 
     // FIXME: Move cleanup to the regular destructor.