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, 81 insertions, 44 deletions

diff --git a/src/components/script/dom/mouseevent.rs b/src/components/script/dom/mouseevent.rs
index 9db7963c2c9..fbd0abfc4d4 100644
--- a/src/components/script/dom/mouseevent.rs
+++ b/src/components/script/dom/mouseevent.rs
@@ -3,13 +3,13 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use dom::bindings::codegen::BindingDeclarations::MouseEventBinding;
-use dom::bindings::codegen::InheritTypes::MouseEventDerived;
-use dom::bindings::js::JS;
+use dom::bindings::codegen::InheritTypes::{UIEventCast, MouseEventDerived};
+use dom::bindings::js::{JS, JSRef, RootedReference, Temporary, OptionalSettable};
 use dom::bindings::error::Fallible;
 use dom::bindings::utils::{Reflectable, Reflector, reflect_dom_object};
 use dom::event::{Event, MouseEventTypeId};
 use dom::eventtarget::EventTarget;
-use dom::uievent::UIEvent;
+use dom::uievent::{UIEvent, UIEventMethods};
 use dom::window::Window;
 use servo_util::str::DOMString;
 
@@ -51,91 +51,127 @@ impl MouseEvent {
         }
     }
 
-    pub fn new(window: &JS<Window>) -> JS<MouseEvent> {
+    pub fn new(window: &JSRef<Window>) -> Temporary<MouseEvent> {
         reflect_dom_object(~MouseEvent::new_inherited(),
                            window,
                            MouseEventBinding::Wrap)
     }
 
-    pub fn Constructor(owner: &JS<Window>,
+    pub fn Constructor(owner: &JSRef<Window>,
                        type_: DOMString,
-                       init: &MouseEventBinding::MouseEventInit) -> Fallible<JS<MouseEvent>> {
-        let mut ev = MouseEvent::new(owner);
-        ev.get_mut().InitMouseEvent(type_, init.bubbles, init.cancelable, init.view.clone(),
-                                      init.detail, init.screenX, init.screenY,
-                                      init.clientX, init.clientY, init.ctrlKey,
-                                      init.altKey, init.shiftKey, init.metaKey,
-                                      init.button, init.relatedTarget.clone());
-        Ok(ev)
+                       init: &MouseEventBinding::MouseEventInit) -> Fallible<Temporary<MouseEvent>> {
+        let mut ev = MouseEvent::new(owner).root();
+        ev.InitMouseEvent(type_, init.bubbles, init.cancelable, init.view.root_ref(),
+                          init.detail, init.screenX, init.screenY,
+                          init.clientX, init.clientY, init.ctrlKey,
+                          init.altKey, init.shiftKey, init.metaKey,
+                          init.button, init.relatedTarget.root_ref());
+        Ok(Temporary::from_rooted(&*ev))
     }
+}
+
+pub trait MouseEventMethods {
+    fn ScreenX(&self) -> i32;
+    fn ScreenY(&self) -> i32;
+    fn ClientX(&self) -> i32;
+    fn ClientY(&self) -> i32;
+    fn CtrlKey(&self) -> bool;
+    fn ShiftKey(&self) -> bool;
+    fn AltKey(&self) -> bool;
+    fn MetaKey(&self) -> bool;
+    fn Button(&self) -> u16;
+    fn Buttons(&self)-> u16;
+    fn GetRelatedTarget(&self) -> Option<Temporary<EventTarget>>;
+    fn GetModifierState(&self, _keyArg: DOMString) -> bool;
+    fn InitMouseEvent(&mut self,
+                      typeArg: DOMString,
+                      canBubbleArg: bool,
+                      cancelableArg: bool,
+                      viewArg: Option<JSRef<Window>>,
+                      detailArg: i32,
+                      screenXArg: i32,
+                      screenYArg: i32,
+                      clientXArg: i32,
+                      clientYArg: i32,
+                      ctrlKeyArg: bool,
+                      altKeyArg: bool,
+                      shiftKeyArg: bool,
+                      metaKeyArg: bool,
+                      buttonArg: u16,
+                      relatedTargetArg: Option<JSRef<EventTarget>>);
+}
 
-    pub fn ScreenX(&self) -> i32 {
+impl<'a> MouseEventMethods for JSRef<'a, MouseEvent> {
+    fn ScreenX(&self) -> i32 {
         self.screen_x
     }
 
-    pub fn ScreenY(&self) -> i32 {
+    fn ScreenY(&self) -> i32 {
         self.screen_y
     }
 
-    pub fn ClientX(&self) -> i32 {
+    fn ClientX(&self) -> i32 {
         self.client_x
     }
 
-    pub fn ClientY(&self) -> i32 {
+    fn ClientY(&self) -> i32 {
         self.client_y
     }
 
-    pub fn CtrlKey(&self) -> bool {
+    fn CtrlKey(&self) -> bool {
         self.ctrl_key
     }
 
-    pub fn ShiftKey(&self) -> bool {
+    fn ShiftKey(&self) -> bool {
         self.shift_key
     }
 
-    pub fn AltKey(&self) -> bool {
+    fn AltKey(&self) -> bool {
         self.alt_key
     }
 
-    pub fn MetaKey(&self) -> bool {
+    fn MetaKey(&self) -> bool {
         self.meta_key
     }
 
-    pub fn Button(&self) -> u16 {
+    fn Button(&self) -> u16 {
         self.button
     }
 
-    pub fn Buttons(&self)-> u16 {
+    fn Buttons(&self)-> u16 {
         //TODO
         0
     }
 
-    pub fn GetRelatedTarget(&self) -> Option<JS<EventTarget>> {
-        self.related_target.clone()
+    fn GetRelatedTarget(&self) -> Option<Temporary<EventTarget>> {
+        self.related_target.clone().map(|target| Temporary::new(target))
     }
 
-    pub fn GetModifierState(&self, _keyArg: DOMString) -> bool {
+    fn GetModifierState(&self, _keyArg: DOMString) -> bool {
         //TODO
         false
     }
 
-    pub fn InitMouseEvent(&mut self,
-                          typeArg: DOMString,
-                          canBubbleArg: bool,
-                          cancelableArg: bool,
-                          viewArg: Option<JS<Window>>,
-                          detailArg: i32,
-                          screenXArg: i32,
-                          screenYArg: i32,
-                          clientXArg: i32,
-                          clientYArg: i32,
-                          ctrlKeyArg: bool,
-                          altKeyArg: bool,
-                          shiftKeyArg: bool,
-                          metaKeyArg: bool,
-                          buttonArg: u16,
-                          relatedTargetArg: Option<JS<EventTarget>>) {
-        self.mouseevent.InitUIEvent(typeArg, canBubbleArg, cancelableArg, viewArg, detailArg);
+    fn InitMouseEvent(&mut self,
+                      typeArg: DOMString,
+                      canBubbleArg: bool,
+                      cancelableArg: bool,
+                      viewArg: Option<JSRef<Window>>,
+                      detailArg: i32,
+                      screenXArg: i32,
+                      screenYArg: i32,
+                      clientXArg: i32,
+                      clientYArg: i32,
+                      ctrlKeyArg: bool,
+                      altKeyArg: bool,
+                      shiftKeyArg: bool,
+                      metaKeyArg: bool,
+                      buttonArg: u16,
+                      relatedTargetArg: Option<JSRef<EventTarget>>) {
+        {
+            let uievent: &mut JSRef<UIEvent> = UIEventCast::from_mut_ref(self);
+            uievent.InitUIEvent(typeArg, canBubbleArg, cancelableArg, viewArg, detailArg);
+        }
         self.screen_x = screenXArg;
         self.screen_y = screenYArg;
         self.client_x = clientXArg;
@@ -145,10 +181,11 @@ impl MouseEvent {
         self.shift_key = shiftKeyArg;
         self.meta_key = metaKeyArg;
         self.button = buttonArg;
-        self.related_target = relatedTargetArg;
+        self.related_target.assign(relatedTargetArg);
     }
 }
 
+
 impl Reflectable for MouseEvent {
     fn reflector<'a>(&'a self) -> &'a Reflector {
         self.mouseevent.reflector()