LibWeb: Add basic support for HTMLInputElement.form

HTMLInputElement now inherits from FormAssociatedElement, which will
be a common base for the handful of elements that need to track their
owner form (and register with it for the form.elements collection.)

At the moment, the owner form is assigned during DOM insertion/removal
of an HTMLInputElement. I didn't implement any of the legacy behaviors
defined by the HTML parsing spec yet.

8 files changed, 110 insertions, 4 deletions

diff --git a/Userland/Libraries/LibWeb/CMakeLists.txt b/Userland/Libraries/LibWeb/CMakeLists.txt
index 110d3247f1..5361b96482 100644
--- a/Userland/Libraries/LibWeb/CMakeLists.txt
+++ b/Userland/Libraries/LibWeb/CMakeLists.txt
@@ -67,6 +67,7 @@ set(SOURCES
     HTML/AttributeNames.cpp
     HTML/CanvasRenderingContext2D.cpp
     HTML/EventNames.cpp
+    HTML/FormAssociatedElement.cpp
     HTML/FrameHostElement.cpp
     HTML/GlobalEventHandlers.cpp
     HTML/HTMLAnchorElement.cpp
diff --git a/Userland/Libraries/LibWeb/CodeGenerators/WrapperGenerator.cpp b/Userland/Libraries/LibWeb/CodeGenerators/WrapperGenerator.cpp
index 9a4311ad3b..bf7f4660da 100644
--- a/Userland/Libraries/LibWeb/CodeGenerators/WrapperGenerator.cpp
+++ b/Userland/Libraries/LibWeb/CodeGenerators/WrapperGenerator.cpp
@@ -865,6 +865,7 @@ void generate_implementation(const IDL::Interface& interface)
 #include <LibWeb/Bindings/EventTargetWrapperFactory.h>
 #include <LibWeb/Bindings/EventWrapperFactory.h>
 #include <LibWeb/Bindings/HTMLCanvasElementWrapper.h>
+#include <LibWeb/Bindings/HTMLFormElementWrapper.h>
 #include <LibWeb/Bindings/HTMLHeadElementWrapper.h>
 #include <LibWeb/Bindings/HTMLImageElementWrapper.h>
 #include <LibWeb/Bindings/ImageDataWrapper.h>
@@ -1205,6 +1206,7 @@ void generate_prototype_implementation(const IDL::Interface& interface)
 #include <LibWeb/Bindings/EventWrapperFactory.h>
 #include <LibWeb/Bindings/ExceptionOrUtils.h>
 #include <LibWeb/Bindings/HTMLCanvasElementWrapper.h>
+#include <LibWeb/Bindings/HTMLFormElementWrapper.h>
 #include <LibWeb/Bindings/HTMLHeadElementWrapper.h>
 #include <LibWeb/Bindings/HTMLImageElementWrapper.h>
 #include <LibWeb/Bindings/ImageDataWrapper.h>
diff --git a/Userland/Libraries/LibWeb/HTML/FormAssociatedElement.cpp b/Userland/Libraries/LibWeb/HTML/FormAssociatedElement.cpp
new file mode 100644
index 0000000000..5026c6067e
--- /dev/null
+++ b/Userland/Libraries/LibWeb/HTML/FormAssociatedElement.cpp
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2021, 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 <LibWeb/HTML/FormAssociatedElement.h>
+#include <LibWeb/HTML/HTMLFormElement.h>
+
+namespace Web::HTML {
+
+void FormAssociatedElement::set_form(HTMLFormElement* form)
+{
+    m_form = form;
+}
+
+}
diff --git a/Userland/Libraries/LibWeb/HTML/FormAssociatedElement.h b/Userland/Libraries/LibWeb/HTML/FormAssociatedElement.h
new file mode 100644
index 0000000000..2e7a405adf
--- /dev/null
+++ b/Userland/Libraries/LibWeb/HTML/FormAssociatedElement.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2021, 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/WeakPtr.h>
+#include <LibWeb/Forward.h>
+
+namespace Web::HTML {
+
+class FormAssociatedElement {
+public:
+    HTMLFormElement* form() { return m_form; }
+    HTMLFormElement const* form() const { return m_form; }
+
+    void set_form(HTMLFormElement*);
+
+protected:
+    FormAssociatedElement() { }
+
+private:
+    WeakPtr<HTMLFormElement> m_form;
+};
+
+}
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLFormElement.h b/Userland/Libraries/LibWeb/HTML/HTMLFormElement.h
index 8c5b3d1669..0368880494 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLFormElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLFormElement.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
index 25efe4d7c5..350ff84014 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -138,4 +138,14 @@ void HTMLInputElement::create_shadow_tree_if_needed()
     set_shadow_root(move(shadow_root));
 }
 
+void HTMLInputElement::inserted()
+{
+    set_form(first_ancestor_of_type<HTMLFormElement>());
+}
+
+void HTMLInputElement::removed_from(DOM::Node*)
+{
+    set_form(nullptr);
+}
+
 }
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h
index 51387371df..ff8cf6d8c7 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,11 +26,14 @@
 
 #pragma once
 
+#include <LibWeb/HTML/FormAssociatedElement.h>
 #include <LibWeb/HTML/HTMLElement.h>
 
 namespace Web::HTML {
 
-class HTMLInputElement final : public HTMLElement {
+class HTMLInputElement final
+    : public HTMLElement
+    , public FormAssociatedElement {
 public:
     using WrapperType = Bindings::HTMLInputElementWrapper;
 
@@ -54,6 +57,9 @@ public:
     void did_click_button(Badge<Layout::ButtonBox>);
 
 private:
+    virtual void inserted() override;
+    virtual void removed_from(Node*) override;
+
     void create_shadow_tree_if_needed();
 
     RefPtr<DOM::Text> m_text_node;
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.idl b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.idl
index 1fe526d6cc..361de54d65 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.idl
+++ b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.idl
@@ -1,5 +1,7 @@
 interface HTMLInputElement : HTMLElement {
 
+    readonly attribute HTMLFormElement? form;
+
     [Reflect] attribute DOMString accept;
     [Reflect] attribute DOMString alt;
     [Reflect] attribute DOMString max;