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, 67 insertions, 40 deletions

diff --git a/src/components/script/dom/htmlbuttonelement.rs b/src/components/script/dom/htmlbuttonelement.rs
index d40fdbe94be..782e9a0c0c8 100644
--- a/src/components/script/dom/htmlbuttonelement.rs
+++ b/src/components/script/dom/htmlbuttonelement.rs
@@ -4,14 +4,14 @@
 
 use dom::bindings::codegen::BindingDeclarations::HTMLButtonElementBinding;
 use dom::bindings::codegen::InheritTypes::HTMLButtonElementDerived;
-use dom::bindings::js::JS;
+use dom::bindings::js::{JSRef, Temporary};
 use dom::bindings::error::ErrorResult;
 use dom::document::Document;
 use dom::element::HTMLButtonElementTypeId;
 use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
 use dom::htmlformelement::HTMLFormElement;
-use dom::node::{Node, ElementNodeTypeId};
+use dom::node::{Node, ElementNodeTypeId, window_from_node};
 use dom::validitystate::ValidityState;
 use servo_util::str::DOMString;
 
@@ -30,131 +30,158 @@ impl HTMLButtonElementDerived for EventTarget {
 }
 
 impl HTMLButtonElement {
-    pub fn new_inherited(localName: DOMString, document: JS<Document>) -> HTMLButtonElement {
+    pub fn new_inherited(localName: DOMString, document: &JSRef<Document>) -> HTMLButtonElement {
         HTMLButtonElement {
             htmlelement: HTMLElement::new_inherited(HTMLButtonElementTypeId, localName, document)
         }
     }
 
-    pub fn new(localName: DOMString, document: &JS<Document>) -> JS<HTMLButtonElement> {
-        let element = HTMLButtonElement::new_inherited(localName, document.clone());
+    pub fn new(localName: DOMString, document: &JSRef<Document>) -> Temporary<HTMLButtonElement> {
+        let element = HTMLButtonElement::new_inherited(localName, document);
         Node::reflect_node(~element, document, HTMLButtonElementBinding::Wrap)
     }
 }
 
-impl HTMLButtonElement {
-    pub fn Autofocus(&self) -> bool {
+pub trait HTMLButtonElementMethods {
+    fn Autofocus(&self) -> bool;
+    fn SetAutofocus(&mut self, _autofocus: bool) -> ErrorResult;
+    fn Disabled(&self) -> bool;
+    fn SetDisabled(&mut self, _disabled: bool) -> ErrorResult;
+    fn GetForm(&self) -> Option<Temporary<HTMLFormElement>>;
+    fn FormAction(&self) -> DOMString;
+    fn SetFormAction(&mut self, _formaction: DOMString) -> ErrorResult;
+    fn FormEnctype(&self) -> DOMString;
+    fn SetFormEnctype(&mut self, _formenctype: DOMString) -> ErrorResult;
+    fn FormMethod(&self) -> DOMString;
+    fn SetFormMethod(&mut self, _formmethod: DOMString) -> ErrorResult;
+    fn FormNoValidate(&self) -> bool;
+    fn SetFormNoValidate(&mut self, _novalidate: bool) -> ErrorResult;
+    fn FormTarget(&self) -> DOMString;
+    fn SetFormTarget(&mut self, _formtarget: DOMString) -> ErrorResult;
+    fn Name(&self) -> DOMString;
+    fn SetName(&mut self, _name: DOMString) -> ErrorResult;
+    fn Type(&self) -> DOMString;
+    fn SetType(&mut self, _type: DOMString) -> ErrorResult;
+    fn Value(&self) -> DOMString;
+    fn SetValue(&mut self, _value: DOMString) -> ErrorResult;
+    fn WillValidate(&self) -> bool;
+    fn SetWillValidate(&mut self, _will_validate: bool);
+    fn Validity(&self) -> Temporary<ValidityState>;
+    fn ValidationMessage(&self) -> DOMString;
+    fn SetValidationMessage(&mut self, _message: DOMString) -> ErrorResult;
+    fn CheckValidity(&self) -> bool;
+    fn SetCustomValidity(&mut self, _error: DOMString);
+}
+
+impl<'a> HTMLButtonElementMethods for JSRef<'a, HTMLButtonElement> {
+    fn Autofocus(&self) -> bool {
         false
     }
 
-    pub fn SetAutofocus(&mut self, _autofocus: bool) -> ErrorResult {
+    fn SetAutofocus(&mut self, _autofocus: bool) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Disabled(&self) -> bool {
+    fn Disabled(&self) -> bool {
         false
     }
 
-    pub fn SetDisabled(&mut self, _disabled: bool) -> ErrorResult {
+    fn SetDisabled(&mut self, _disabled: bool) -> ErrorResult {
         Ok(())
     }
 
-    pub fn GetForm(&self) -> Option<JS<HTMLFormElement>> {
+    fn GetForm(&self) -> Option<Temporary<HTMLFormElement>> {
         None
     }
 
-    pub fn FormAction(&self) -> DOMString {
+    fn FormAction(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetFormAction(&mut self, _formaction: DOMString) -> ErrorResult {
+    fn SetFormAction(&mut self, _formaction: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn FormEnctype(&self) -> DOMString {
+    fn FormEnctype(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetFormEnctype(&mut self, _formenctype: DOMString) -> ErrorResult {
+    fn SetFormEnctype(&mut self, _formenctype: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn FormMethod(&self) -> DOMString {
+    fn FormMethod(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetFormMethod(&mut self, _formmethod: DOMString) -> ErrorResult {
+    fn SetFormMethod(&mut self, _formmethod: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn FormNoValidate(&self) -> bool {
+    fn FormNoValidate(&self) -> bool {
         false
     }
 
-    pub fn SetFormNoValidate(&mut self, _novalidate: bool) -> ErrorResult {
+    fn SetFormNoValidate(&mut self, _novalidate: bool) -> ErrorResult {
         Ok(())
     }
 
-    pub fn FormTarget(&self) -> DOMString {
+    fn FormTarget(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetFormTarget(&mut self, _formtarget: DOMString) -> ErrorResult {
+    fn SetFormTarget(&mut self, _formtarget: 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 Type(&self) -> DOMString {
+    fn Type(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetType(&mut self, _type: DOMString) -> ErrorResult {
+    fn SetType(&mut self, _type: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn Value(&self) -> DOMString {
+    fn Value(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetValue(&mut self, _value: DOMString) -> ErrorResult {
+    fn SetValue(&mut self, _value: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn WillValidate(&self) -> bool {
+    fn WillValidate(&self) -> bool {
         false
     }
 
-    pub fn SetWillValidate(&mut self, _will_validate: bool) {
-    }
-
-    pub fn Validity(&self) -> JS<ValidityState> {
-        let doc = self.htmlelement.element.node.owner_doc();
-        let doc = doc.get();
-        ValidityState::new(&doc.window)
+    fn SetWillValidate(&mut self, _will_validate: bool) {
     }
 
-    pub fn SetValidity(&mut self, _validity: JS<ValidityState>) {
+    fn Validity(&self) -> Temporary<ValidityState> {
+        let window = window_from_node(self).root();
+        ValidityState::new(&*window)
     }
 
-    pub fn ValidationMessage(&self) -> DOMString {
+    fn ValidationMessage(&self) -> DOMString {
         ~""
     }
 
-    pub fn SetValidationMessage(&mut self, _message: DOMString) -> ErrorResult {
+    fn SetValidationMessage(&mut self, _message: DOMString) -> ErrorResult {
         Ok(())
     }
 
-    pub fn CheckValidity(&self) -> bool {
+    fn CheckValidity(&self) -> bool {
         true
     }
 
-    pub fn SetCustomValidity(&mut self, _error: DOMString) {
+    fn SetCustomValidity(&mut self, _error: DOMString) {
     }
 }