LibWeb: Start generating JS wrappers from (simplified) WebIDL :^)

This patch introduces a hackish but functional IDL parser and uses it
to generate the JS bindings for Node and Document.

We'll see how far this simple parser takes us. The important thing
right now is generating code, not being a perfect IDL parser. :^)

Libraries/LibWeb/Bindings/CanvasRenderingContext2DWrapper.cpp

@@ -34,6 +34,7 @@
 #include <LibWeb/Bindings/CanvasRenderingContext2DWrapper.h>
 #include <LibWeb/Bindings/HTMLImageElementWrapper.h>
 #include <LibWeb/Bindings/ImageDataWrapper.h>
+#include <LibWeb/Bindings/NodeWrapperFactory.h>
 #include <LibWeb/DOM/CanvasRenderingContext2D.h>
 #include <LibWeb/DOM/HTMLCanvasElement.h>
 #include <LibWeb/DOM/HTMLImageElement.h>

Libraries/LibWeb/Bindings/DocumentWrapper.cpp

@@ -1,134 +0,0 @@
-/*
- * Copyright (c) 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.
- */
-
-#include <AK/FlyString.h>
-#include <LibJS/Interpreter.h>
-#include <LibJS/Runtime/Array.h>
-#include <LibJS/Runtime/Error.h>
-#include <LibJS/Runtime/GlobalObject.h>
-#include <LibJS/Runtime/PrimitiveString.h>
-#include <LibJS/Runtime/Value.h>
-#include <LibWeb/Bindings/DocumentWrapper.h>
-#include <LibWeb/DOM/Document.h>
-#include <LibWeb/DOM/Element.h>
-
-namespace Web {
-namespace Bindings {
-
-DocumentWrapper::DocumentWrapper(JS::GlobalObject& global_object, Document& document)
-    : NodeWrapper(global_object, document)
-{
-}
-
-void DocumentWrapper::initialize(JS::Interpreter& interpreter, JS::GlobalObject& global_object)
-{
-    NodeWrapper::initialize(interpreter, global_object);
-    define_native_function("getElementById", get_element_by_id, 1);
-    define_native_function("querySelector", query_selector, 1);
-    define_native_function("querySelectorAll", query_selector_all, 1);
-}
-
-DocumentWrapper::~DocumentWrapper()
-{
-}
-
-Document& DocumentWrapper::node()
-{
-    return static_cast<Document&>(NodeWrapper::node());
-}
-
-const Document& DocumentWrapper::node() const
-{
-    return static_cast<const Document&>(NodeWrapper::node());
-}
-
-static Document* impl_from(JS::Interpreter& interpreter, JS::GlobalObject& global_object)
-{
-    auto* this_object = interpreter.this_value(global_object).to_object(interpreter, global_object);
-    if (!this_object)
-        return {};
-    if (StringView("DocumentWrapper") != this_object->class_name()) {
-        interpreter.throw_exception<JS::TypeError>(JS::ErrorType::NotA, "DocumentWrapper");
-        return {};
-    }
-    return &static_cast<DocumentWrapper*>(this_object)->node();
-}
-
-JS_DEFINE_NATIVE_FUNCTION(DocumentWrapper::get_element_by_id)
-{
-    auto* document = impl_from(interpreter, global_object);
-    if (!document)
-        return {};
-    if (!interpreter.argument_count())
-        return interpreter.throw_exception<JS::TypeError>(JS::ErrorType::BadArgCountOne, "getElementById");
-    auto id = interpreter.argument(0).to_string(interpreter);
-    if (interpreter.exception())
-        return {};
-    auto* element = document->get_element_by_id(id);
-    if (!element)
-        return JS::js_null();
-    return wrap(interpreter.heap(), const_cast<Element&>(*element));
-}
-
-JS_DEFINE_NATIVE_FUNCTION(DocumentWrapper::query_selector)
-{
-    auto* document = impl_from(interpreter, global_object);
-    if (!document)
-        return {};
-    if (!interpreter.argument_count())
-        return interpreter.throw_exception<JS::TypeError>(JS::ErrorType::BadArgCountOne, "querySelector");
-    auto selector = interpreter.argument(0).to_string(interpreter);
-    if (interpreter.exception())
-        return {};
-    // FIXME: Throw if selector is invalid
-    auto element = document->query_selector(selector);
-    if (!element)
-        return JS::js_null();
-    return wrap(interpreter.heap(), *element);
-}
-
-JS_DEFINE_NATIVE_FUNCTION(DocumentWrapper::query_selector_all)
-{
-    auto* document = impl_from(interpreter, global_object);
-    if (!document)
-        return {};
-    if (!interpreter.argument_count())
-        return interpreter.throw_exception<JS::TypeError>(JS::ErrorType::BadArgCountOne, "querySelectorAll");
-    auto selector = interpreter.argument(0).to_string(interpreter);
-    if (interpreter.exception())
-        return {};
-    // FIXME: Throw if selector is invalid
-    auto elements = document->query_selector_all(selector);
-    // FIXME: This should be a static NodeList, not a plain JS::Array.
-    auto* node_list = JS::Array::create(global_object);
-    for (auto& element : elements) {
-        node_list->indexed_properties().append(wrap(interpreter.heap(), element));
-    }
-    return node_list;
-}
-
-}
-}

Libraries/LibWeb/Bindings/DocumentWrapper.h

@@ -1,52 +0,0 @@
-/*
- * Copyright (c) 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 <LibWeb/Bindings/NodeWrapper.h>
-
-namespace Web {
-namespace Bindings {
-
-class DocumentWrapper : public NodeWrapper {
-public:
-    DocumentWrapper(JS::GlobalObject&, Document&);
-    virtual void initialize(JS::Interpreter&, JS::GlobalObject&) override;
-    virtual ~DocumentWrapper() override;
-
-    Document& node();
-    const Document& node() const;
-
-private:
-    virtual const char* class_name() const override { return "DocumentWrapper"; }
-
-    JS_DECLARE_NATIVE_FUNCTION(get_element_by_id);
-    JS_DECLARE_NATIVE_FUNCTION(query_selector);
-    JS_DECLARE_NATIVE_FUNCTION(query_selector_all);
-};
-
-}
-}

Libraries/LibWeb/Bindings/ElementWrapper.cpp

@@ -61,12 +61,12 @@ ElementWrapper::~ElementWrapper()
 
 Element& ElementWrapper::node()
 {
-    return static_cast<Element&>(NodeWrapper::node());
+    return static_cast<Element&>(NodeWrapper::impl());
 }
 
 const Element& ElementWrapper::node() const
 {
-    return static_cast<const Element&>(NodeWrapper::node());
+    return static_cast<const Element&>(NodeWrapper::impl());
 }
 
 static Element* impl_from(JS::Interpreter& interpreter, JS::GlobalObject& global_object)

Libraries/LibWeb/Bindings/HTMLCanvasElementWrapper.cpp

@@ -57,12 +57,12 @@ HTMLCanvasElementWrapper::~HTMLCanvasElementWrapper()
 
 HTMLCanvasElement& HTMLCanvasElementWrapper::node()
 {
-    return static_cast<HTMLCanvasElement&>(NodeWrapper::node());
+    return static_cast<HTMLCanvasElement&>(NodeWrapper::impl());
 }
 
 const HTMLCanvasElement& HTMLCanvasElementWrapper::node() const
 {
-    return static_cast<const HTMLCanvasElement&>(NodeWrapper::node());
+    return static_cast<const HTMLCanvasElement&>(NodeWrapper::impl());
 }
 
 static HTMLCanvasElement* impl_from(JS::Interpreter& interpreter, JS::GlobalObject& global_object)

Libraries/LibWeb/Bindings/HTMLImageElementWrapper.cpp

@@ -46,12 +46,12 @@ HTMLImageElementWrapper::~HTMLImageElementWrapper()
 
 HTMLImageElement& HTMLImageElementWrapper::node()
 {
-    return static_cast<HTMLImageElement&>(NodeWrapper::node());
+    return static_cast<HTMLImageElement&>(NodeWrapper::impl());
 }
 
 const HTMLImageElement& HTMLImageElementWrapper::node() const
 {
-    return static_cast<const HTMLImageElement&>(NodeWrapper::node());
+    return static_cast<const HTMLImageElement&>(NodeWrapper::impl());
 }
 
 }

Libraries/LibWeb/Bindings/NodeWrapperFactory.cpp

@@ -24,9 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <AK/FlyString.h>
-#include <LibJS/Runtime/PrimitiveString.h>
-#include <LibJS/Runtime/Value.h>
+#include <LibJS/Interpreter.h>
 #include <LibWeb/Bindings/DocumentWrapper.h>
 #include <LibWeb/Bindings/HTMLCanvasElementWrapper.h>
 #include <LibWeb/Bindings/HTMLImageElementWrapper.h>
@@ -52,30 +50,5 @@ NodeWrapper* wrap(JS::Heap& heap, Node& node)
     return static_cast<NodeWrapper*>(wrap_impl(heap, node));
 }
 
-NodeWrapper::NodeWrapper(JS::GlobalObject& global_object, Node& node)
-    : EventTargetWrapper(global_object, node)
-{
-}
-
-void NodeWrapper::initialize(JS::Interpreter& interpreter, JS::GlobalObject& global_object)
-{
-    EventTargetWrapper::initialize(interpreter, global_object);
-    put("nodeName", JS::js_string(interpreter.heap(), node().node_name()));
-}
-
-NodeWrapper::~NodeWrapper()
-{
-}
-
-Node& NodeWrapper::node()
-{
-    return static_cast<Node&>(EventTargetWrapper::impl());
-}
-
-const Node& NodeWrapper::node() const
-{
-    return static_cast<const Node&>(EventTargetWrapper::impl());
-}
-
 }
 }

Libraries/LibWeb/Bindings/NodeWrapperFactory.h

@@ -26,24 +26,12 @@
 
 #pragma once
 
-#include <LibWeb/Bindings/EventTargetWrapper.h>
+#include <LibWeb/Forward.h>
+#include <LibJS/Forward.h>
 
 namespace Web {
 namespace Bindings {
 
-class NodeWrapper : public EventTargetWrapper {
-public:
-    NodeWrapper(JS::GlobalObject&, Node&);
-    virtual void initialize(JS::Interpreter&, JS::GlobalObject&) override;
-    virtual ~NodeWrapper() override;
-
-    Node& node();
-    const Node& node() const;
-
-private:
-    virtual const char* class_name() const override { return "NodeWrapper"; }
-};
-
 NodeWrapper* wrap(JS::Heap&, Node&);
 
 }

Libraries/LibWeb/Bindings/WindowObject.cpp

@@ -36,6 +36,7 @@
 #include <LibWeb/Bindings/DocumentWrapper.h>
 #include <LibWeb/Bindings/LocationObject.h>
 #include <LibWeb/Bindings/NavigatorObject.h>
+#include <LibWeb/Bindings/NodeWrapperFactory.h>
 #include <LibWeb/Bindings/WindowObject.h>
 #include <LibWeb/Bindings/XMLHttpRequestConstructor.h>
 #include <LibWeb/Bindings/XMLHttpRequestPrototype.h>

Libraries/LibWeb/CMakeLists.txt

@@ -1,6 +1,7 @@
 set(SOURCES
     Bindings/CanvasRenderingContext2DWrapper.cpp
     Bindings/DocumentWrapper.cpp
+    Bindings/DocumentWrapper.h
     Bindings/ElementWrapper.cpp
     Bindings/EventListenerWrapper.cpp
     Bindings/EventTargetWrapper.cpp
@@ -12,6 +13,8 @@ set(SOURCES
     Bindings/MouseEventWrapper.cpp
     Bindings/NavigatorObject.cpp
     Bindings/NodeWrapper.cpp
+    Bindings/NodeWrapper.h
+    Bindings/NodeWrapperFactory.cpp
     Bindings/WindowObject.cpp
     Bindings/Wrappable.cpp
     Bindings/XMLHttpRequestConstructor.cpp
@@ -123,6 +126,46 @@ set(GENERATED_SOURCES
     ../../Services/ProtocolServer/ProtocolServerEndpoint.h
 )
 
+add_custom_command(
+    OUTPUT Bindings/NodeWrapper.h
+    COMMAND /bin/mkdir -p Bindings
+    COMMAND WrapperGenerator --header ${CMAKE_CURRENT_SOURCE_DIR}/DOM/Node.idl > Bindings/NodeWrapper.h
+    VERBATIM
+    DEPENDS WrapperGenerator
+    MAIN_DEPENDENCY DOM/Node.idl
+)
+add_custom_target(generate_NodeWrapper.h DEPENDS Bindings/NodeWrapper.h)
+
+add_custom_command(
+    OUTPUT Bindings/NodeWrapper.cpp
+    COMMAND /bin/mkdir -p Bindings
+    COMMAND WrapperGenerator --implementation ${CMAKE_CURRENT_SOURCE_DIR}/DOM/Node.idl > Bindings/NodeWrapper.cpp
+    VERBATIM
+    DEPENDS WrapperGenerator
+    MAIN_DEPENDENCY DOM/Node.idl
+)
+add_custom_target(generate_NodeWrapper.cpp DEPENDS Bindings/NodeWrapper.cpp)
+
+add_custom_command(
+    OUTPUT Bindings/DocumentWrapper.h
+    COMMAND /bin/mkdir -p Bindings
+    COMMAND WrapperGenerator --header ${CMAKE_CURRENT_SOURCE_DIR}/DOM/Document.idl > Bindings/DocumentWrapper.h
+    VERBATIM
+    DEPENDS WrapperGenerator
+    MAIN_DEPENDENCY DOM/Document.idl
+)
+add_custom_target(generate_DocumentWrapper.h DEPENDS Bindings/DocumentWrapper.h)
+
+add_custom_command(
+    OUTPUT Bindings/DocumentWrapper.cpp
+    COMMAND /bin/mkdir -p Bindings
+    COMMAND WrapperGenerator --implementation ${CMAKE_CURRENT_SOURCE_DIR}/DOM/Document.idl > Bindings/DocumentWrapper.cpp
+    VERBATIM
+    DEPENDS WrapperGenerator
+    MAIN_DEPENDENCY DOM/Document.idl
+)
+add_custom_target(generate_DocumentWrapper.cpp DEPENDS Bindings/DocumentWrapper.cpp)
+
 add_custom_command(
     OUTPUT CSS/PropertyID.h
     COMMAND /bin/mkdir -p CSS

Libraries/LibWeb/CodeGenerators/CMakeLists.txt

@@ -1,4 +1,6 @@
 add_executable(Generate_CSS_PropertyID_h Generate_CSS_PropertyID_h.cpp)
 add_executable(Generate_CSS_PropertyID_cpp Generate_CSS_PropertyID_cpp.cpp)
+add_executable(WrapperGenerator WrapperGenerator.cpp)
 target_link_libraries(Generate_CSS_PropertyID_h LagomCore)
 target_link_libraries(Generate_CSS_PropertyID_cpp LagomCore)
+target_link_libraries(WrapperGenerator LagomCore)

Libraries/LibWeb/CodeGenerators/WrapperGenerator.cpp

@@ -0,0 +1,487 @@
+/*
+ * Copyright (c) 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.
+ */
+
+#include <AK/ByteBuffer.h>
+#include <AK/StringBuilder.h>
+#include <LibCore/ArgsParser.h>
+#include <LibCore/File.h>
+#include <ctype.h>
+
+static String snake_name(const StringView& camel_name)
+{
+    StringBuilder builder;
+    for (auto ch : camel_name) {
+        if (isupper(ch)) {
+            builder.append('_');
+            builder.append(tolower(ch));
+        } else {
+            builder.append(ch);
+        }
+    }
+    return builder.to_string();
+}
+
+namespace IDL {
+
+struct Type {
+    String name;
+    bool nullable { false };
+};
+
+struct Parameter {
+    Type type;
+    String name;
+};
+
+struct Function {
+    Type return_type;
+    String name;
+    Vector<Parameter> parameters;
+
+    size_t length() const
+    {
+        // FIXME: Take optional arguments into account
+        return parameters.size();
+    }
+};
+
+struct Attribute {
+    bool readonly { false };
+    Type type;
+    String name;
+
+    // Added for convenience after parsing
+    String getter_callback_name;
+    String setter_callback_name;
+};
+
+struct Interface {
+    String name;
+    String parent_name;
+
+    Vector<Attribute> attributes;
+    Vector<Function> functions;
+
+    // Added for convenience after parsing
+    String wrapper_class;
+    String wrapper_base_class;
+};
+
+static String snake_name(const StringView& camel_name)
+{
+    StringBuilder builder;
+    for (auto ch : camel_name) {
+        if (isupper(ch)) {
+            builder.append('_');
+            builder.append(tolower(ch));
+        } else {
+            builder.append(ch);
+        }
+    }
+    return builder.to_string();
+}
+
+OwnPtr<Interface> parse_interface(const StringView& input)
+{
+    auto interface = make<Interface>();
+
+    size_t index = 0;
+
+    auto peek = [&](size_t offset = 0) -> char {
+        if (index + offset > input.length())
+            return 0;
+        return input[index + offset];
+    };
+
+    auto consume = [&] {
+        return input[index++];
+    };
+
+    auto consume_if = [&](auto ch) {
+        if (peek() == ch) {
+            consume();
+            return true;
+        }
+        return false;
+    };
+
+    auto consume_specific = [&](char ch) {
+        auto consumed = consume();
+        if (consumed != ch) {
+            dbg() << "Expected '" << ch << "' at offset " << index << " but got '" << consumed << "'";
+            ASSERT_NOT_REACHED();
+        }
+    };
+
+    auto consume_whitespace = [&] {
+        while (isspace(peek()))
+            consume();
+    };
+
+    auto consume_string = [&](const StringView& string) {
+        for (size_t i = 0; i < string.length(); ++i) {
+            ASSERT(consume() == string[i]);
+        }
+    };
+
+    auto next_is = [&](const StringView& string) {
+        for (size_t i = 0; i < string.length(); ++i) {
+            if (peek(i) != string[i])
+                return false;
+        }
+        return true;
+    };
+
+    auto consume_while = [&](auto condition) {
+        StringBuilder builder;
+        while (index < input.length() && condition(peek())) {
+            builder.append(consume());
+        }
+        return builder.to_string();
+    };
+
+    consume_string("interface");
+    consume_whitespace();
+    interface->name = consume_while([](auto ch) { return !isspace(ch); });
+    consume_whitespace();
+    if (consume_if(':')) {
+        consume_whitespace();
+        interface->parent_name = consume_while([](auto ch) { return !isspace(ch); });
+        consume_whitespace();
+    }
+    consume_specific('{');
+
+    auto parse_type = [&] {
+        auto name = consume_while([](auto ch) { return !isspace(ch) && ch != '?'; });
+        auto nullable = peek() == '?';
+        if (nullable)
+            consume_specific('?');
+        return Type { name, nullable };
+    };
+
+    auto parse_attribute = [&] {
+        bool readonly = false;
+        if (next_is("readonly")) {
+            consume_string("readonly");
+            readonly = true;
+            consume_whitespace();
+        }
+        if (next_is("attribute")) {
+            consume_string("attribute");
+            consume_whitespace();
+        }
+        auto type = parse_type();
+        consume_whitespace();
+        auto name = consume_while([](auto ch) { return !isspace(ch) && ch != ';'; });
+        consume_specific(';');
+        Attribute attribute;
+        attribute.readonly = readonly;
+        attribute.type = type;
+        attribute.name = name;
+        attribute.getter_callback_name = String::format("%s_getter", snake_name(attribute.name).characters());
+        attribute.setter_callback_name = String::format("%s_setter", snake_name(attribute.name).characters());
+        interface->attributes.append(move(attribute));
+    };
+
+    auto parse_function = [&] {
+        auto return_type = parse_type();
+        consume_whitespace();
+        auto name = consume_while([](auto ch) { return !isspace(ch) && ch != '('; });
+        consume_specific('(');
+
+        Vector<Parameter> parameters;
+
+        for (;;) {
+            auto type = parse_type();
+            consume_whitespace();
+            auto name = consume_while([](auto ch) { return !isspace(ch) && ch != ',' && ch != ')'; });
+            parameters.append({ move(type), move(name) });
+            if (consume_if(')'))
+                break;
+            consume_specific(',');
+            consume_whitespace();
+        }
+
+        consume_specific(';');
+
+        interface->functions.append(Function { return_type, name, move(parameters) });
+    };
+
+    for (;;) {
+
+        consume_whitespace();
+
+        if (consume_if('}'))
+            break;
+
+        if (next_is("readonly") || next_is("attribute")) {
+            parse_attribute();
+            continue;
+        }
+
+        parse_function();
+    }
+
+    interface->wrapper_class = String::format("%sWrapper", interface->name.characters());
+    interface->wrapper_base_class = String::format("%sWrapper", interface->parent_name.characters());
+
+    return interface;
+}
+
+}
+
+static void generate_header(const IDL::Interface&);
+static void generate_implementation(const IDL::Interface&);
+
+int main(int argc, char** argv)
+{
+    Core::ArgsParser args_parser;
+    const char* path = nullptr;
+    bool header_mode = false;
+    bool implementation_mode = false;
+    args_parser.add_option(header_mode, "Generate the wrapper .h file", "header", 'H');
+    args_parser.add_option(implementation_mode, "Generate the wrapper .cpp file", "implementation", 'I');
+    args_parser.add_positional_argument(path, "IDL file", "idl-file");
+    args_parser.parse(argc, argv);
+
+    auto file_or_error = Core::File::open(path, Core::IODevice::ReadOnly);
+    if (file_or_error.is_error()) {
+        fprintf(stderr, "Cannot open %s\n", path);
+        return 1;
+    }
+
+    auto data = file_or_error.value()->read_all();
+    auto interface = IDL::parse_interface(data);
+
+    if (!interface) {
+        fprintf(stderr, "Cannot parse %s\n", path);
+        return 1;
+    }
+
+#if 0
+    dbg() << "Attributes:";
+    for (auto& attribute : interface->attributes) {
+        dbg() << "  " << (attribute.readonly ? "Readonly " : "")
+              << attribute.type.name << (attribute.type.nullable ? "?" : "")
+              << " " << attribute.name;
+    }
+
+    dbg() << "Functions:";
+    for (auto& function : interface->functions) {
+        dbg() << "  " << function.return_type.name << (function.return_type.nullable ? "?" : "")
+              << " " << function.name;
+        for (auto& parameter : function.parameters) {
+            dbg() << "    " << parameter.type.name << (parameter.type.nullable ? "?" : "") << " " << parameter.name;
+        }
+    }
+#endif
+
+    if (header_mode)
+        generate_header(*interface);
+
+    if (implementation_mode)
+        generate_implementation(*interface);
+
+    return 0;
+}
+
+static void generate_header(const IDL::Interface& interface)
+{
+    auto& wrapper_class = interface.wrapper_class;
+    auto& wrapper_base_class = interface.wrapper_base_class;
+
+    out() << "#pragma once";
+    out() << "#include <LibWeb/Bindings/Wrapper.h>";
+    out() << "#include <LibWeb/DOM/" << interface.name << ".h>";
+
+    if (!wrapper_base_class.is_empty()) {
+        out() << "#include <LibWeb/Bindings/" << wrapper_base_class << ".h>";
+    }
+
+    out() << "namespace Web {";
+    out() << "namespace Bindings {";
+
+    out() << "class " << wrapper_class << " : public " << wrapper_base_class << " {";
+    out() << "public:";
+    out() << "    " << wrapper_class << "(JS::GlobalObject&, " << interface.name << "&);";
+    out() << "    virtual void initialize(JS::Interpreter&, JS::GlobalObject&) override;";
+    out() << "    virtual ~" << wrapper_class << "() override;";
+
+    if (wrapper_base_class.is_empty()) {
+        out() << "    " << interface.name << "& impl() { return *m_impl; }";
+        out() << "    const " << interface.name << "& impl() const { return *m_impl; }";
+    } else {
+        out() << "    " << interface.name << "& impl() { return static_cast<" << interface.name << "&>(" << wrapper_base_class << "::impl()); }";
+        out() << "    const " << interface.name << "& impl() const { return static_cast<const " << interface.name << "&>(" << wrapper_base_class << "::impl()); }";
+    }
+
+    out() << "private:";
+    out() << "    virtual const char* class_name() const override { return \"" << interface.name << "\"; }";
+
+    for (auto& function : interface.functions) {
+        out() << "    JS_DECLARE_NATIVE_FUNCTION(" << snake_name(function.name) << ");";
+    }
+
+    for (auto& attribute : interface.attributes) {
+        out() << "    JS_DECLARE_NATIVE_GETTER(" << snake_name(attribute.name) << "_getter);";
+        if (!attribute.readonly)
+            out() << "    JS_DECLARE_NATIVE_SETTER(" << snake_name(attribute.name) << "_setter);";
+    }
+
+    out() << "};";
+    out() << "}";
+    out() << "}";
+}
+
+void generate_implementation(const IDL::Interface& interface)
+{
+    auto& wrapper_class = interface.wrapper_class;
+    auto& wrapper_base_class = interface.wrapper_base_class;
+
+    out() << "#include <AK/FlyString.h>";
+    out() << "#include <LibJS/Interpreter.h>";
+    out() << "#include <LibJS/Runtime/Array.h>";
+    out() << "#include <LibJS/Runtime/Value.h>";
+    out() << "#include <LibJS/Runtime/GlobalObject.h>";
+    out() << "#include <LibJS/Runtime/Error.h>";
+    out() << "#include <LibWeb/Bindings/NodeWrapperFactory.h>";
+    out() << "#include <LibWeb/Bindings/" << wrapper_class << ".h>";
+    out() << "#include <LibWeb/DOM/Element.h>";
+
+    out() << "namespace Web {";
+    out() << "namespace Bindings {";
+
+    // Implementation: Wrapper constructor
+    out() << wrapper_class << "::" << wrapper_class << "(JS::GlobalObject& global_object, " << interface.name << "& impl)";
+    out() << "    : " << wrapper_base_class << "(global_object, impl)";
+    out() << "{";
+    out() << "}";
+
+    // Implementation: Wrapper initialize()
+    out() << "void " << wrapper_class << "::initialize(JS::Interpreter& interpreter, JS::GlobalObject& global_object)";
+    out() << "{";
+    out() << "    [[maybe_unused]] u8 default_attributes = JS::Attribute::Enumerable | JS::Attribute::Configurable;";
+    out() << "    " << wrapper_base_class << "::initialize(interpreter, global_object);";
+
+    for (auto& attribute : interface.attributes) {
+        out() << "    define_native_property(\"" << attribute.name << "\", " << attribute.getter_callback_name << ", " << (attribute.readonly ? "nullptr" : attribute.setter_callback_name) << ", default_attributes);";
+    }
+
+    for (auto& function : interface.functions) {
+        out() << "    define_native_function(\"" << function.name << "\", " << snake_name(function.name) << ", " << function.length() << ", default_attributes);";
+    }
+
+    out() << "}";
+
+    // Implementation: Wrapper destructor
+    out() << wrapper_class << "::~" << wrapper_class << "()";
+    out() << "{";
+    out() << "}";
+
+    // Implementation: impl_from()
+    out() << "static " << interface.name << "* impl_from(JS::Interpreter& interpreter, JS::GlobalObject& global_object)";
+    out() << "{";
+    out() << "    auto* this_object = interpreter.this_value(global_object).to_object(interpreter, global_object);";
+    out() << "    if (!this_object)";
+    out() << "        return {};";
+    out() << "    if (StringView(\"" << interface.name << "\") != this_object->class_name()) {";
+    out() << "        interpreter.throw_exception<JS::TypeError>(JS::ErrorType::NotA, \"" << interface.name << "\");";
+    out() << "        return nullptr;";
+    out() << "    }";
+    out() << "    return &static_cast<" << wrapper_class << "*>(this_object)->impl();";
+    out() << "}";
+
+    auto generate_return_statement = [&](auto& return_type) {
+        if (return_type.nullable) {
+            out() << "    if (!retval)";
+            out() << "        return JS::js_null();";
+        }
+
+        if (return_type.name == "DOMString") {
+            out() << "    return JS::js_string(interpreter, retval);";
+        } else if (return_type.name == "ArrayFromVector") {
+            // FIXME: Remove this fake type hack once it's no longer needed.
+            //        Basically once we have NodeList we can throw this out.
+            out() << "    auto* new_array = JS::Array::create(global_object);";
+            out() << "    for (auto& element : retval) {";
+            out() << "        new_array->indexed_properties().append(wrap(interpreter.heap(), element));";
+            out() << "    }";
+            out() << "    return new_array;";
+        } else {
+            out() << "    return wrap(interpreter.heap(), const_cast<" << return_type.name << "&>(*retval));";
+        }
+    };
+
+    // Implementation: Attributes
+    for (auto& attribute : interface.attributes) {
+        out() << "JS_DEFINE_NATIVE_GETTER(" << wrapper_class << "::" << snake_name(attribute.name) << "_getter)";
+        out() << "{";
+        out() << "    auto* impl = impl_from(interpreter, global_object);";
+        out() << "    if (!impl)";
+        out() << "        return {};";
+        out() << "    auto retval = impl->" << snake_name(attribute.name) << "();";
+        generate_return_statement(attribute.type);
+        out() << "}";
+    }
+
+    // Implementation: Functions
+    for (auto& function : interface.functions) {
+        out() << "JS_DEFINE_NATIVE_FUNCTION(" << wrapper_class << "::" << snake_name(function.name) << ")";
+        out() << "{";
+        out() << "    auto* impl = impl_from(interpreter, global_object);";
+        out() << "    if (!impl)";
+        out() << "        return {};";
+        out() << "    if (interpreter.argument_count() < " << function.length() << ")";
+        out() << "        return interpreter.throw_exception<JS::TypeError>(JS::ErrorType::BadArgCountMany, \"" << function.name << "\", \"" << function.length() << "\");";
+
+        Vector<String> parameter_names;
+        size_t argument_index = 0;
+        for (auto& parameter : function.parameters) {
+            parameter_names.append(parameter.name);
+            if (parameter.type.name == "DOMString") {
+                out() << "    auto " << snake_name(parameter.name) << " = interpreter.argument(" << argument_index << ").to_string(interpreter);";
+                out() << "    if (interpreter.exception())";
+                out() << "        return {};";
+            }
+            ++argument_index;
+        }
+
+        StringBuilder arguments_builder;
+        arguments_builder.join(", ", parameter_names);
+
+        if (function.return_type.name != "void") {
+            out() << "    auto retval = impl->" << snake_name(function.name) << "(" << arguments_builder.to_string() << ");";
+        } else {
+            out() << "    impl->" << snake_name(function.name) << "(" << arguments_builder.to_string() << ");";
+        }
+
+        generate_return_statement(function.return_type);
+        out() << "}";
+    }
+
+    out() << "}";
+    out() << "}";
+}

Libraries/LibWeb/DOM/Document.idl

@@ -0,0 +1,7 @@
+interface Document : Node {
+
+    Element? getElementById(DOMString id);
+    Element? querySelector(DOMString selectors);
+    ArrayFromVector querySelectorAll(DOMString selectors);
+
+}

Libraries/LibWeb/DOM/Node.cpp

@@ -32,6 +32,7 @@
 #include <LibJS/Runtime/ScriptFunction.h>
 #include <LibWeb/Bindings/EventWrapper.h>
 #include <LibWeb/Bindings/NodeWrapper.h>
+#include <LibWeb/Bindings/NodeWrapperFactory.h>
 #include <LibWeb/CSS/StyleResolver.h>
 #include <LibWeb/DOM/Element.h>
 #include <LibWeb/DOM/Event.h>

Libraries/LibWeb/DOM/Node.idl

@@ -0,0 +1,10 @@
+interface Node : EventTarget {
+
+    readonly attribute DOMString nodeName;
+    readonly attribute Node? firstChild;
+    readonly attribute Node? lastChild;
+    readonly attribute Node? previousSibling;
+    readonly attribute Node? nextSibling;
+
+}
+