LibHTML: Create some subdirectories.

LibHTML/DOM/Node.h

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <AK/Badge.h>
+#include <AK/RetainPtr.h>
+#include <AK/Vector.h>
+
+enum class NodeType : unsigned {
+    INVALID = 0,
+    ELEMENT_NODE = 1,
+    TEXT_NODE = 3,
+    DOCUMENT_NODE = 9,
+};
+
+class LayoutNode;
+class ParentNode;
+
+class Node {
+public:
+    virtual ~Node();
+
+    void retain();
+    void release();
+    int retain_count() const { return m_retain_count; }
+
+    ParentNode* parent_node() { return m_parent_node; }
+    const ParentNode* parent_node() const { return m_parent_node; }
+
+    void set_parent_node(Badge<ParentNode>, ParentNode* parent_node) { m_parent_node = parent_node; }
+
+    NodeType type() const { return m_type; }
+    bool is_element() const { return type() == NodeType::ELEMENT_NODE; }
+    bool is_text() const { return type() == NodeType::TEXT_NODE; }
+    bool is_document() const { return type() == NodeType::DOCUMENT_NODE; }
+    bool is_parent_node() const { return is_element() || is_document(); }
+
+    Node* next_sibling() { return m_next_sibling; }
+    Node* previous_sibling() { return m_previous_sibling; }
+    const Node* next_sibling() const { return m_next_sibling; }
+    const Node* previous_sibling() const { return m_previous_sibling; }
+
+    void set_next_sibling(Node* node) { m_next_sibling = node; }
+    void set_previous_sibling(Node* node) { m_previous_sibling = node; }
+
+    virtual RetainPtr<LayoutNode> create_layout_node();
+
+    const LayoutNode* layout_node() const { return m_layout_node; }
+    LayoutNode* layout_node() { return m_layout_node; }
+
+    void set_layout_node(Retained<LayoutNode>);
+
+protected:
+    explicit Node(NodeType);
+
+    int m_retain_count { 1 };
+    NodeType m_type { NodeType::INVALID };
+    ParentNode* m_parent_node { nullptr };
+    Node* m_next_sibling { nullptr };
+    Node* m_previous_sibling { nullptr };
+    RetainPtr<LayoutNode> m_layout_node;
+};