Create a mechanism to automatically reset relevant members of Document during Document.open

[jdm]

There are a lot of members that need to be reset to initial states during Document.open. Right now it's just a list of reinitializations in that method, which is not very maintainable. We should have a structure that contains the members that need to be cleared, and auto-derive a trait for every member. This will make it impossible to forget to clear a member, and will make it easy to tell if a member is reinitialized or not by looking at the member initialization list for Document.

[Dylan-DPC]

Hey. I can take this up

[jdm]

That would be great! Please ask questions if anything is unclear!

[jdm]

@Dylan-DPC Are you still working on this?

[Dylan-DPC]

Hey got a bit busy so didn't get time. If anyone else wants to take it then fine else i'll look into it during the coming weekend.

[jdm]

I'll mark it unassigned in the time being. Let us know if you start working on it!

[nipunG314]

Hi. I would like to take this up if this is still pending.

Just to clarify, I have to refactor the Open function residing in components/script/dom/document.rs.

servo/components/script/dom/document.rs

Lines 4431 to 4435 in fb5ab1f

	fn Open(
	&self,
	_unused1: Option<DOMString>,
	_unused2: Option<DOMString>,
	) -> Fallible<DomRoot<Document>> {

I can see that this method consists of a number of steps. Steps 8 to 15 seem to responsible for reinitializing the members of the Document struct. So when I create a struct to automatically reset the relevant members, there would be one auto-derived trait for each step. And the corresponding step's code would be moved into that trait.

Is that correct, or have I missed anything?

servo/components/script/dom/document.rs

Lines 4481 to 4525 in fb5ab1f

	// Step 8
	for node in self
	.upcast::<Node>()
	.traverse_preorder(ShadowIncluding::Yes)
	{
	node.upcast::<EventTarget>().remove_all_listeners();
	}
	// Step 9
	if self.window.Document() == DomRoot::from_ref(self) {
	self.window.upcast::<EventTarget>().remove_all_listeners();
	}
	// Step 10
	// TODO: https://github.com/servo/servo/issues/21936
	Node::replace_all(None, self.upcast::<Node>());
	// Step 11
	if self.is_fully_active() {
	let mut new_url = entry_responsible_document.url();
	if entry_responsible_document != DomRoot::from_ref(self) {
	new_url.set_fragment(None);
	}
	// TODO: https://github.com/servo/servo/issues/21939
	self.set_url(new_url);
	}
	// Step 12
	// TODO: https://github.com/servo/servo/issues/21938
	// Step 13
	self.set_quirks_mode(QuirksMode::NoQuirks);
	// Step 14
	let resource_threads = self
	.window
	.upcast::<GlobalScope>()
	.resource_threads()
	.clone();
	*self.loader.borrow_mut() =
	DocumentLoader::new_with_threads(resource_threads, Some(self.url()));
	ServoParser::parse_html_script_input(self, self.url());
	// Step 15
	self.ready_state.set(DocumentReadyState::Loading);

[jdm]

I suspect this code has changed in the 2.5 years since I filed this issue. I'm pretty sure the code I had mind back when was this code, but it's not clear to me if my proposal still makes sense.