auto merge of #2101 : jdm/servo/newroot_rebase, r=Ms2ger

As described in #1764, this strategy uses the following properties:
* DOM members are `JS<T>` types. These cannot be used with being explicitly rooted, but they are required for compiler-derived trace hooks.
* Methods that take DOM type arguments receive `&[mut] JSRef<T>`. These are rooted value references that are cloneable but cannot escape.
* Methods that return DOM values use `Unrooted<T>`. These are values that may or may not be rooted elsewhere, but callers must root them in order to interact with them in any way. One unsoundness hole exists - `Unrooted` values must be rooted ASAP, or there exists the danger that JSAPI calls could be made that could cause the underlying JS value to be GCed.
* All methods are implemented on `JSRef<T>`, enforcing the requirement that all DOM values are rooted for the duration of a method call (with a few exceptions for layout-related code, which cannot root values and therefore interacts with `JS<T>` and `&T` values - this is safe under the assumption that layout code interacts with DOM nodes that are in the tree, therefore rooted, and does not run concurrently with content code)

1 files changed, 59 insertions, 33 deletions

diff --git a/src/components/script/dom/htmlformelement.rs b/src/components/script/dom/htmlformelement.rs
index 3fdf2a4ba7f..445ad6e0831 100644
--- a/src/components/script/dom/htmlformelement.rs
+++ b/src/components/script/dom/htmlformelement.rs
@@ -4,14 +4,14 @@
 
 use dom::bindings::codegen::BindingDeclarations::HTMLFormElementBinding;
 use dom::bindings::codegen::InheritTypes::HTMLFormElementDerived;
-use dom::bindings::js::JS;
+use dom::bindings::js::{JSRef, Temporary};
 use dom::bindings::error::ErrorResult;
 use dom::document::Document;
 use dom::element::{Element, HTMLFormElementTypeId};
 use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlcollection::{HTMLCollection, Static};
 use dom::htmlelement::HTMLElement;
-use dom::node::{Node, ElementNodeTypeId};
+use dom::node::{Node, ElementNodeTypeId, window_from_node};
 use servo_util::str::DOMString;
 
 #[deriving(Encodable)]
@@ -29,114 +29,140 @@ impl HTMLFormElementDerived for EventTarget {
 }
 
 impl HTMLFormElement {
-    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLFormElement {
+    pub fn new_inherited(localName: DOMString, document: &JSRef<Document>) -> HTMLFormElement {
         HTMLFormElement {
             htmlelement: HTMLElement::new_inherited(HTMLFormElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLFormElement> {
-        let element = HTMLFormElement::new_inherited(localName, document.clone());
+    pub fn new(localName: DOMString, document: &JSRef<Document>) -> Temporary<HTMLFormElement> {
+        let element = HTMLFormElement::new_inherited(localName, document);
         Node::reflect_node(~element, document, HTMLFormElementBinding::Wrap)
     }
 }
 
-impl HTMLFormElement {
-    pub fn AcceptCharset(&self) -> DOMString {
+pub trait HTMLFormElementMethods {
+    fn AcceptCharset(&self) -> DOMString;
+    fn SetAcceptCharset(&mut self, _accept_charset: DOMString) -> ErrorResult;
+    fn Action(&self) -> DOMString;
+    fn SetAction(&mut self, _action: DOMString) -> ErrorResult;
+    fn Autocomplete(&self) -> DOMString;
+    fn SetAutocomplete(&mut self, _autocomplete: DOMString) -> ErrorResult;
+    fn Enctype(&self) -> DOMString;
+    fn SetEnctype(&mut self, _enctype: DOMString) -> ErrorResult;
+    fn Encoding(&self) -> DOMString;
+    fn SetEncoding(&mut self, _encoding: DOMString) -> ErrorResult;
+    fn Method(&self) -> DOMString;
+    fn SetMethod(&mut self, _method: DOMString) -> ErrorResult;
+    fn Name(&self) -> DOMString;
+    fn SetName(&mut self, _name: DOMString) -> ErrorResult;
+    fn NoValidate(&self) -> bool;
+    fn SetNoValidate(&mut self, _no_validate: bool) -> ErrorResult;
+    fn Target(&self) -> DOMString;
+    fn SetTarget(&mut self, _target: DOMString) -> ErrorResult;
+    fn Elements(&self) -> Temporary<HTMLCollection>;
+    fn Length(&self) -> i32;
+    fn Submit(&self) -> ErrorResult;
+    fn Reset(&self);
+    fn CheckValidity(&self) -> bool;
+    fn IndexedGetter(&self, _index: u32, _found: &mut bool) -> Temporary<Element>;
+}
+
+impl<'a> HTMLFormElementMethods for JSRef<'a, HTMLFormElement> {
+    fn AcceptCharset(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetAcceptCharset(&mut self, _accept_charset: DOMString) -> ErrorResult {
+    fn SetAcceptCharset(&mut self, _accept_charset: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Action(&self) -> DOMString {
+    fn Action(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetAction(&mut self, _action: DOMString) -> ErrorResult {
+    fn SetAction(&mut self, _action: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Autocomplete(&self) -> DOMString {
+    fn Autocomplete(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetAutocomplete(&mut self, _autocomplete: DOMString) -> ErrorResult {
+    fn SetAutocomplete(&mut self, _autocomplete: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Enctype(&self) -> DOMString {
+    fn Enctype(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetEnctype(&mut self, _enctype: DOMString) -> ErrorResult {
+    fn SetEnctype(&mut self, _enctype: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Encoding(&self) -> DOMString {
+    fn Encoding(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetEncoding(&mut self, _encoding: DOMString) -> ErrorResult {
+    fn SetEncoding(&mut self, _encoding: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Method(&self) -> DOMString {
+    fn Method(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetMethod(&mut self, _method: DOMString) -> ErrorResult {
+    fn SetMethod(&mut self, _method: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Name(&self) -> DOMString {
+    fn Name(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetName(&mut self, _name: DOMString) -> ErrorResult {
+    fn SetName(&mut self, _name: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn NoValidate(&self) -> bool {
+    fn NoValidate(&self) -> bool {
         false
     }
 
-    pub fn SetNoValidate(&mut self, _no_validate: bool) -> ErrorResult {
+    fn SetNoValidate(&mut self, _no_validate: bool) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Target(&self) -> DOMString {
+    fn Target(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetTarget(&mut self, _target: DOMString) -> ErrorResult {
+    fn SetTarget(&mut self, _target: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Elements(&self) -> JS<HTMLCollection> {
+    fn Elements(&self) -> Temporary<HTMLCollection> {
         // FIXME: https://github.com/mozilla/servo/issues/1844
-        let doc = self.htmlelement.element.node.owner_doc();
-        let doc = doc.get();
-        HTMLCollection::new(&doc.window, Static(vec!()))
+        let window = window_from_node(self).root();
+        HTMLCollection::new(&*window, Static(vec!()))
     }
 
-    pub fn Length(&self) -> i32 {
+    fn Length(&self) -> i32 {
         0
     }
 
-    pub fn Submit(&self) -> ErrorResult {
+    fn Submit(&self) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Reset(&self) {
+    fn Reset(&self) {
     }
 
-    pub fn CheckValidity(&self) -> bool {
+    fn CheckValidity(&self) -> bool {
         false
     }
 
-    pub fn IndexedGetter(&self, _index: u32, _found: &mut bool) -> JS<Element> {
+    fn IndexedGetter(&self, _index: u32, _found: &mut bool) -> Temporary<Element> {
         fail!("Not implemented.")
     }
 }