LibWeb: Implement ChildNode.after

Author: https://github.com/Lubrsi
Commit: https://github.com/SerenityOS/serenity/commit/5a5e3a6ec38
Pull-request: https://github.com/SerenityOS/serenity/pull/12208
Reviewed-by: https://github.com/awesomekling

Userland/Libraries/LibWeb/DOM/CharacterData.idl

@@ -8,6 +8,7 @@ interface CharacterData : Node {
 
     // FIXME: These should come from a ChildNode mixin
     [CEReactions, Unscopable] undefined before((Node or DOMString)... nodes);
+    [CEReactions, Unscopable] undefined after((Node or DOMString)... nodes);
     [CEReactions, Unscopable, ImplementedAs=remove_binding] undefined remove();
 
 };

Userland/Libraries/LibWeb/DOM/ChildNode.h

@@ -51,6 +51,36 @@ public:
         return {};
     }
 
+    // https://dom.spec.whatwg.org/#dom-childnode-after
+    ExceptionOr<void> after(Vector<Variant<NonnullRefPtr<Node>, String>> const& nodes)
+    {
+        auto* node = static_cast<NodeType*>(this);
+
+        // 1. Let parent be this’s parent.
+        auto* parent = node->parent();
+
+        // 2. If parent is null, then return.
+        if (!parent)
+            return {};
+
+        // 3. Let viableNextSibling be this’s first following sibling not in nodes; otherwise null.
+        auto viable_next_sibling = viable_nest_sibling_for_insertion(nodes);
+
+        // 4. Let node be the result of converting nodes into a node, given nodes and this’s node document.
+        auto node_or_exception = convert_nodes_to_single_node(nodes, node->document());
+        if (node_or_exception.is_exception())
+            return node_or_exception.exception();
+
+        auto node_to_insert = node_or_exception.release_value();
+
+        // 5. Pre-insert node into parent before viableNextSibling.
+        auto result = parent->pre_insert(node_to_insert, viable_next_sibling);
+        if (result.is_exception())
+            return result.exception();
+
+        return {};
+    }
+
     // https://dom.spec.whatwg.org/#dom-childnode-remove
     void remove_binding()
     {
@@ -92,6 +122,31 @@ private:
 
         return nullptr;
     }
+
+    RefPtr<Node> viable_nest_sibling_for_insertion(Vector<Variant<NonnullRefPtr<Node>, String>> const& nodes) const
+    {
+        auto* node = static_cast<NodeType const*>(this);
+
+        while (auto* next_sibling = node->next_sibling()) {
+            bool contained_in_nodes = false;
+
+            for (auto const& node_or_string : nodes) {
+                if (!node_or_string.template has<NonnullRefPtr<Node>>())
+                    continue;
+
+                auto node_in_vector = node_or_string.template get<NonnullRefPtr<Node>>();
+                if (node_in_vector.ptr() == next_sibling) {
+                    contained_in_nodes = true;
+                    break;
+                }
+            }
+
+            if (!contained_in_nodes)
+                return next_sibling;
+        }
+
+        return nullptr;
+    }
 };
 
 }

Userland/Libraries/LibWeb/DOM/DocumentType.idl

@@ -6,6 +6,7 @@ interface DocumentType : Node {
 
     // FIXME: These should come from a ChildNode mixin
     [CEReactions, Unscopable] undefined before((Node or DOMString)... nodes);
+    [CEReactions, Unscopable] undefined after((Node or DOMString)... nodes);
     [CEReactions, Unscopable, ImplementedAs=remove_binding] undefined remove();
 
 };

Userland/Libraries/LibWeb/DOM/Element.idl

@@ -56,6 +56,7 @@ interface Element : Node {
 
     // FIXME: These should come from a ChildNode mixin
     [CEReactions, Unscopable] undefined before((Node or DOMString)... nodes);
+    [CEReactions, Unscopable] undefined after((Node or DOMString)... nodes);
     [CEReactions, Unscopable, ImplementedAs=remove_binding] undefined remove();
 
 };