auto merge of #4526 : servo/servo/deref-1, r=Manishearth

This is a start towards fixing #3868. Not all callers have been fixed yet, so the `Deref` implementation remains for now.

components/script/dom/bindings/callback.rs

@@ -147,7 +147,7 @@ impl CallSetup {
     pub fn new<T: CallbackContainer>(callback: T, handling: ExceptionHandling) -> CallSetup {
         let global = global_object_for_js_object(callback.callback());
         let global = global.root();
-        let cx = global.root_ref().get_cx();
+        let cx = global.r().get_cx();
         CallSetup {
             cx: cx,
             _handling: handling

components/script/dom/bindings/codegen/CodegenRust.py

@@ -2199,7 +2199,7 @@ class CGCallGenerator(CGThing):
         if static:
             call = CGWrapper(call, pre="%s::" % descriptorProvider.interface.identifier.name)
         else:
-            call = CGWrapper(call, pre="%s." % object)
+            call = CGWrapper(call, pre="%s.r()." % object)
         call = CGList([call, CGWrapper(args, pre="(", post=")")])
 
         self.cgRoot.append(CGList([
@@ -2214,7 +2214,7 @@ class CGCallGenerator(CGThing):
             if static:
                 glob = ""
             else:
-                glob = "        let global = global_object_for_js_object(this.reflector().get_jsobject());\n"\
+                glob = "        let global = global_object_for_js_object(this.r().reflector().get_jsobject());\n"\
                        "        let global = global.root();\n"
 
             self.cgRoot.append(CGGeneric(
@@ -2222,7 +2222,7 @@ class CGCallGenerator(CGThing):
                 "    Ok(result) => result,\n"
                 "    Err(e) => {\n"
                 "%s"
-                "        throw_dom_exception(cx, global.root_ref(), e);\n"
+                "        throw_dom_exception(cx, global.r(), e);\n"
                 "        return%s;\n"
                 "    },\n"
                 "};" % (glob, errorResult)))
@@ -2307,7 +2307,7 @@ class CGPerSignatureCall(CGThing):
         def process(arg, i):
             argVal = "arg" + str(i)
             if arg.type.isGeckoInterface() and not arg.type.unroll().inner.isCallback():
-                argVal += ".root_ref()"
+                argVal += ".r()"
             return argVal
         return [(a, process(a, i)) for (i, a) in enumerate(self.arguments)]
 
@@ -3540,7 +3540,7 @@ class CGProxySpecialOperation(CGPerSignatureCall):
         def process(arg):
             argVal = arg.identifier.name
             if arg.type.isGeckoInterface() and not arg.type.unroll().inner.isCallback():
-                argVal += ".root_ref()"
+                argVal += ".r()"
             return argVal
         args = [(a, process(a)) for a in self.arguments]
         if self.idlNode.isGetter():
@@ -4014,7 +4014,7 @@ let global = global_object_for_js_object(JS_CALLEE(cx, vp).to_object());
 let global = global.root();
 """)
         nativeName = MakeNativeName(self._ctor.identifier.name)
-        callGenerator = CGMethodCall(["&global.root_ref()"], nativeName, True,
+        callGenerator = CGMethodCall(["&global.r()"], nativeName, True,
                                      self.descriptor, self._ctor)
         return CGList([preamble, callGenerator])
 

components/script/dom/bindings/codegen/Configuration.py

@@ -156,7 +156,7 @@ class Descriptor(DescriptorProvider):
             self.needsRooting = True
             self.returnType = "Temporary<%s>" % ifaceName
             self.argumentType = "JSRef<%s>" % ifaceName
-            self.memberType = "Root<'a, 'b, %s>" % ifaceName
+            self.memberType = "Root<%s>" % ifaceName
             self.nativeType = "JS<%s>" % ifaceName
 
         self.concreteType = ifaceName

components/script/dom/bindings/conversions.rs

@@ -471,9 +471,9 @@ impl<T: Reflectable+IDLInterface> FromJSValConvertible<()> for JS<T> {
     }
 }
 
-impl<'a, 'b, T: Reflectable> ToJSValConvertible for Root<'a, 'b, T> {
+impl<T: Reflectable> ToJSValConvertible for Root<T> {
     fn to_jsval(&self, cx: *mut JSContext) -> JSVal {
-        self.reflector().to_jsval(cx)
+        self.r().reflector().to_jsval(cx)
     }
 }
 

components/script/dom/bindings/global.rs

@@ -32,9 +32,9 @@ pub enum GlobalRef<'a> {
 }
 
 /// A stack-based rooted reference to a global object.
-pub enum GlobalRoot<'a, 'b> {
-    Window(Root<'a, 'b, window::Window>),
-    Worker(Root<'a, 'b, WorkerGlobalScope>),
+pub enum GlobalRoot {
+    Window(Root<window::Window>),
+    Worker(Root<WorkerGlobalScope>),
 }
 
 /// A traced reference to a global object, for use in fields of traced Rust
@@ -98,13 +98,13 @@ impl<'a> Reflectable for GlobalRef<'a> {
     }
 }
 
-impl<'a, 'b> GlobalRoot<'a, 'b> {
+impl GlobalRoot {
     /// Obtain a safe reference to the global object that cannot outlive the
     /// lifetime of this root.
-    pub fn root_ref<'c>(&'c self) -> GlobalRef<'c> {
+    pub fn r<'c>(&'c self) -> GlobalRef<'c> {
         match *self {
-            GlobalRoot::Window(ref window) => GlobalRef::Window(window.root_ref()),
-            GlobalRoot::Worker(ref worker) => GlobalRef::Worker(worker.root_ref()),
+            GlobalRoot::Window(ref window) => GlobalRef::Window(window.r()),
+            GlobalRoot::Worker(ref worker) => GlobalRef::Worker(worker.r()),
         }
     }
 }

components/script/dom/bindings/js.rs

@@ -31,11 +31,11 @@
 //! Both `Temporary<T>` and `JS<T>` do not allow access to their inner value without explicitly
 //! creating a stack-based root via the `root` method. This returns a `Root<T>`, which causes
 //! the JS-owned value to be uncollectable for the duration of the `Root` object's lifetime.
-//! A `JSRef<T>` can be obtained from a `Root<T>` either by dereferencing the `Root<T>` (`*rooted`)
-//! or explicitly calling the `root_ref` method. These `JSRef<T>` values are not allowed to
-//! outlive their originating `Root<T>`, to ensure that all interactions with the enclosed value
-//! only occur when said value is uncollectable, and will cause static lifetime errors if
-//! misused.
+//! A `JSRef<T>` can be obtained from a `Root<T>` by calling the `r` method. (Dereferencing the
+//! object is still supported, but as it is unsafe, this is deprecated.) These `JSRef<T>` values
+//! are not allowed to outlive their originating `Root<T>`, to ensure that all interactions with
+//! the enclosed value only occur when said value is uncollectable, and will cause static lifetime
+//! errors if misused.
 //!
 //! Other miscellaneous helper traits:
 //!
@@ -91,7 +91,7 @@ impl<T: Reflectable> Temporary<T> {
     }
 
     /// Create a stack-bounded root for this value.
-    pub fn root<'a, 'b>(self) -> Root<'a, 'b, T> {
+    pub fn root(self) -> Root<T> {
         let collection = StackRoots.get().unwrap();
         unsafe {
             Root::new(&**collection, &self.inner)
@@ -150,7 +150,7 @@ impl<T: Reflectable> JS<T> {
 
 
     /// Root this JS-owned value to prevent its collection as garbage.
-    pub fn root<'a, 'b>(&self) -> Root<'a, 'b, T> {
+    pub fn root(&self) -> Root<T> {
         let collection = StackRoots.get().unwrap();
         unsafe {
             Root::new(&**collection, self)
@@ -307,23 +307,23 @@ impl<From, To> JS<From> {
 
 /// Get an `Option<JSRef<T>>` out of an `Option<Root<T>>`
 pub trait RootedReference<T> {
-    fn root_ref<'a>(&'a self) -> Option<JSRef<'a, T>>;
+    fn r<'a>(&'a self) -> Option<JSRef<'a, T>>;
 }
 
-impl<'a, 'b, T: Reflectable> RootedReference<T> for Option<Root<'a, 'b, T>> {
-    fn root_ref<'a>(&'a self) -> Option<JSRef<'a, T>> {
-        self.as_ref().map(|root| root.root_ref())
+impl<T: Reflectable> RootedReference<T> for Option<Root<T>> {
+    fn r<'a>(&'a self) -> Option<JSRef<'a, T>> {
+        self.as_ref().map(|root| root.r())
     }
 }
 
 /// Get an `Option<Option<JSRef<T>>>` out of an `Option<Option<Root<T>>>`
 pub trait OptionalRootedReference<T> {
-    fn root_ref<'a>(&'a self) -> Option<Option<JSRef<'a, T>>>;
+    fn r<'a>(&'a self) -> Option<Option<JSRef<'a, T>>>;
 }
 
-impl<'a, 'b, T: Reflectable> OptionalRootedReference<T> for Option<Option<Root<'a, 'b, T>>> {
-    fn root_ref<'a>(&'a self) -> Option<Option<JSRef<'a, T>>> {
-        self.as_ref().map(|inner| inner.root_ref())
+impl<T: Reflectable> OptionalRootedReference<T> for Option<Option<Root<T>>> {
+    fn r<'a>(&'a self) -> Option<Option<JSRef<'a, T>>> {
+        self.as_ref().map(|inner| inner.r())
     }
 }
 
@@ -367,11 +367,11 @@ impl<T: Assignable<U>, U: Reflectable> OptionalSettable<T> for Cell<Option<JS<U>
 
 /// Root a rootable `Option` type (used for `Option<Temporary<T>>`)
 pub trait OptionalRootable<T> {
-    fn root<'a, 'b>(self) -> Option<Root<'a, 'b, T>>;
+    fn root(self) -> Option<Root<T>>;
 }
 
 impl<T: Reflectable> OptionalRootable<T> for Option<Temporary<T>> {
-    fn root<'a, 'b>(self) -> Option<Root<'a, 'b, T>> {
+    fn root(self) -> Option<Root<T>> {
         self.map(|inner| inner.root())
     }
 }
@@ -389,22 +389,22 @@ impl<'a, T: Reflectable> OptionalUnrootable<T> for Option<JSRef<'a, T>> {
 
 /// Root a rootable `Option` type (used for `Option<JS<T>>`)
 pub trait OptionalRootedRootable<T> {
-    fn root<'a, 'b>(&self) -> Option<Root<'a, 'b, T>>;
+    fn root(&self) -> Option<Root<T>>;
 }
 
 impl<T: Reflectable> OptionalRootedRootable<T> for Option<JS<T>> {
-    fn root<'a, 'b>(&self) -> Option<Root<'a, 'b, T>> {
+    fn root(&self) -> Option<Root<T>> {
         self.as_ref().map(|inner| inner.root())
     }
 }
 
 /// Root a rootable `Option<Option>` type (used for `Option<Option<JS<T>>>`)
 pub trait OptionalOptionalRootedRootable<T> {
-    fn root<'a, 'b>(&self) -> Option<Option<Root<'a, 'b, T>>>;
+    fn root(&self) -> Option<Option<Root<T>>>;
 }
 
 impl<T: Reflectable> OptionalOptionalRootedRootable<T> for Option<Option<JS<T>>> {
-    fn root<'a, 'b>(&self) -> Option<Option<Root<'a, 'b, T>>> {
+    fn root(&self) -> Option<Option<Root<T>>> {
         self.as_ref().map(|inner| inner.root())
     }
 }
@@ -412,17 +412,17 @@ impl<T: Reflectable> OptionalOptionalRootedRootable<T> for Option<Option<JS<T>>>
 
 /// Root a rootable `Result` type (any of `Temporary<T>` or `JS<T>`)
 pub trait ResultRootable<T,U> {
-    fn root<'a, 'b>(self) -> Result<Root<'a, 'b, T>, U>;
+    fn root(self) -> Result<Root<T>, U>;
 }
 
 impl<T: Reflectable, U> ResultRootable<T, U> for Result<Temporary<T>, U> {
-    fn root<'a, 'b>(self) -> Result<Root<'a, 'b, T>, U> {
+    fn root(self) -> Result<Root<T>, U> {
         self.map(|inner| inner.root())
     }
 }
 
 impl<T: Reflectable, U> ResultRootable<T, U> for Result<JS<T>, U> {
-    fn root<'a, 'b>(self) -> Result<Root<'a, 'b, T>, U> {
+    fn root(self) -> Result<Root<T>, U> {
         self.map(|inner| inner.root())
     }
 }
@@ -459,7 +459,7 @@ impl RootCollection {
     }
 
     /// Track a stack-based root to ensure LIFO root ordering
-    fn root<'a, 'b, T: Reflectable>(&self, untracked: &Root<'a, 'b, T>) {
+    fn root<'b, T: Reflectable>(&self, untracked: &Root<T>) {
         unsafe {
             let roots = self.roots.get();
             (*roots).push(untracked.js_ptr);
@@ -468,7 +468,7 @@ impl RootCollection {
     }
 
     /// Stop tracking a stack-based root, asserting if LIFO root ordering has been violated
-    fn unroot<'a, 'b, T: Reflectable>(&self, rooted: &Root<'a, 'b, T>) {
+    fn unroot<'b, T: Reflectable>(&self, rooted: &Root<T>) {
         unsafe {
             let roots = self.roots.get();
             debug!("unrooting {} (expecting {}",
@@ -485,20 +485,20 @@ impl RootCollection {
 /// for the same JS value. `Root`s cannot outlive the associated `RootCollection` object.
 /// Attempts to transfer ownership of a `Root` via moving will trigger dynamic unrooting
 /// failures due to incorrect ordering.
-pub struct Root<'a, 'b, T> {
+pub struct Root<T> {
     /// List that ensures correct dynamic root ordering
-    root_list: &'a RootCollection,
+    root_list: &'static RootCollection,
     /// Reference to rooted value that must not outlive this container
-    jsref: JSRef<'b, T>,
+    jsref: JSRef<'static, T>,
     /// On-stack JS pointer to assuage conservative stack scanner
     js_ptr: *mut JSObject,
 }
 
-impl<'b, 'a: 'b, T: Reflectable> Root<'a, 'b, T> {
+impl<T: Reflectable> Root<T> {
     /// Create a new stack-bounded root for the provided JS-owned value.
     /// It cannot not outlive its associated `RootCollection`, and it contains a `JSRef`
     /// which cannot outlive this new `Root`.
-    fn new(roots: &'a RootCollection, unrooted: &JS<T>) -> Root<'a, 'b, T> {
+    fn new(roots: &'static RootCollection, unrooted: &JS<T>) -> Root<T> {
         let root = Root {
             root_list: roots,
             jsref: JSRef {
@@ -513,19 +513,22 @@ impl<'b, 'a: 'b, T: Reflectable> Root<'a, 'b, T> {
 
     /// Obtain a safe reference to the wrapped JS owned-value that cannot outlive
     /// the lifetime of this root.
-    pub fn root_ref<'b>(&'b self) -> JSRef<'b,T> {
-        self.jsref.clone()
+    pub fn r<'b>(&'b self) -> JSRef<'b, T> {
+        JSRef {
+            ptr: self.jsref.ptr,
+            chain: ContravariantLifetime,
+        }
     }
 }
 
 #[unsafe_destructor]
-impl<'b, 'a: 'b, T: Reflectable> Drop for Root<'a, 'b, T> {
+impl<T: Reflectable> Drop for Root<T> {
     fn drop(&mut self) {
         self.root_list.unroot(self);
     }
 }
 
-impl<'b, 'a: 'b, T: Reflectable> Deref<JSRef<'b, T>> for Root<'a, 'b, T> {
+impl<'b, T: Reflectable> Deref<JSRef<'b, T>> for Root<T> {
     fn deref<'c>(&'c self) -> &'c JSRef<'b, T> {
         &self.jsref
     }

components/script/dom/bindings/utils.rs

@@ -552,7 +552,7 @@ pub extern fn outerize_global(_cx: *mut JSContext, obj: JSHandleObject) -> *mut
         debug!("outerizing");
         let obj = *obj.unnamed_field1;
         let win: Root<window::Window> = unwrap_jsmanaged(obj).unwrap().root();
-        win.browser_context().as_ref().unwrap().window_proxy()
+        win.r().browser_context().as_ref().unwrap().window_proxy()
     }
 }