LibWeb: Rename directory LibHTML => LibWeb

Let's rename this to LibWeb since it aims to provide more parts of the
web platform than just HTML. :^)

Libraries/LibWeb/DOM/Element.h

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/String.h>
+#include <LibWeb/DOM/ParentNode.h>
+#include <LibWeb/Layout/LayoutNode.h>
+
+namespace Web {
+
+class LayoutNodeWithStyle;
+
+class Attribute {
+public:
+    Attribute(const String& name, const String& value)
+        : m_name(name)
+        , m_value(value)
+    {
+    }
+
+    const String& name() const { return m_name; }
+    const String& value() const { return m_value; }
+
+    void set_value(const String& value) { m_value = value; }
+
+private:
+    String m_name;
+    String m_value;
+};
+
+class Element : public ParentNode {
+public:
+    Element(Document&, const String& tag_name);
+    virtual ~Element() override;
+
+    virtual String tag_name() const final { return m_tag_name; }
+
+    bool has_attribute(const String& name) const { return !attribute(name).is_null(); }
+    String attribute(const String& name) const;
+    void set_attribute(const String& name, const String& value);
+
+    void set_attributes(Vector<Attribute>&&);
+
+    template<typename Callback>
+    void for_each_attribute(Callback callback) const
+    {
+        for (auto& attribute : m_attributes)
+            callback(attribute.name(), attribute.value());
+    }
+
+    bool has_class(const StringView&) const;
+
+    virtual void apply_presentational_hints(StyleProperties&) const {}
+    virtual void parse_attribute(const String& name, const String& value);
+
+    void recompute_style();
+
+    LayoutNodeWithStyle* layout_node() { return static_cast<LayoutNodeWithStyle*>(Node::layout_node()); }
+    const LayoutNodeWithStyle* layout_node() const { return static_cast<const LayoutNodeWithStyle*>(Node::layout_node()); }
+
+    String name() const { return attribute("name"); }
+
+    const StyleProperties* resolved_style() const { return m_resolved_style.ptr(); }
+    NonnullRefPtr<StyleProperties> computed_style();
+
+private:
+    RefPtr<LayoutNode> create_layout_node(const StyleProperties* parent_style) const override;
+
+    Attribute* find_attribute(const String& name);
+    const Attribute* find_attribute(const String& name) const;
+
+    String m_tag_name;
+    Vector<Attribute> m_attributes;
+
+    RefPtr<StyleProperties> m_resolved_style;
+};
+
+template<>
+inline bool is<Element>(const Node& node)
+{
+    return node.is_element();
+}
+
+}