Auto merge of #11308 - nox:guarded, r=jdm

Implement [Func]

First part of #11292, this just includes support of `[Func]`.

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components/constellation/constellation.rs

@@ -69,8 +69,9 @@ use style_traits::viewport::ViewportConstraints;
 use timer_scheduler::TimerScheduler;
 use url::Url;
 use util::geometry::PagePx;
+use util::opts;
+use util::prefs::mozbrowser_enabled;
 use util::thread::spawn_named;
-use util::{opts, prefs};
 use webrender_traits;
 
 #[derive(Debug, PartialEq)]
@@ -1129,7 +1130,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
     }
 
     fn handle_alert(&mut self, pipeline_id: PipelineId, message: String, sender: IpcSender<bool>) {
-        let display_alert_dialog = if prefs::get_pref("dom.mozbrowser.enabled").as_boolean().unwrap_or(false) {
+        let display_alert_dialog = if mozbrowser_enabled() {
             let parent_pipeline_info = self.pipelines.get(&pipeline_id).and_then(|source| source.parent_info);
             if let Some(_) = parent_pipeline_info {
                 let root_pipeline_id = self.root_frame_id
@@ -1421,7 +1422,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                                    containing_pipeline_id: PipelineId,
                                    subpage_id: SubpageId,
                                    event: MozBrowserEvent) {
-        assert!(prefs::get_pref("dom.mozbrowser.enabled").as_boolean().unwrap_or(false));
+        assert!(mozbrowser_enabled());
 
         // Find the script channel for the given parent pipeline,
         // and pass the event to that script thread.
@@ -1999,9 +2000,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             if let Some(pipeline_id) = rng.choose(&*pipeline_ids) {
                 if let Some(pipeline) = self.pipelines.get(pipeline_id) {
                     // Don't kill the mozbrowser pipeline
-                    if prefs::get_pref("dom.mozbrowser.enabled").as_boolean().unwrap_or(false) &&
+                    if mozbrowser_enabled() && pipeline.parent_info.is_none() {
-                        pipeline.parent_info.is_none()
-                    {
                         info!("Not closing mozbrowser pipeline {}.", pipeline_id);
                     } else {
                         // Note that we deliberately do not do any of the tidying up
@@ -2089,7 +2088,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
     // https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowserlocationchange
     // Note that this is a no-op if the pipeline is not a mozbrowser iframe
     fn trigger_mozbrowserlocationchange(&self, pipeline_id: PipelineId) {
-        if !prefs::get_pref("dom.mozbrowser.enabled").as_boolean().unwrap_or(false) { return; }
+        if !mozbrowser_enabled() { return; }
 
         let event_info = self.pipelines.get(&pipeline_id).and_then(|pipeline| {
             pipeline.parent_info.map(|(containing_pipeline_id, subpage_id, frame_type)| {
@@ -2115,7 +2114,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
     // https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowsererror
     // Note that this does not require the pipeline to be an immediate child of the root
     fn trigger_mozbrowsererror(&self, pipeline_id: PipelineId, reason: String, backtrace: String) {
-        if !prefs::get_pref("dom.mozbrowser.enabled").as_boolean().unwrap_or(false) { return; }
+        if !mozbrowser_enabled() { return; }
 
         let ancestor_info = self.get_mozbrowser_ancestor_info(pipeline_id);
 

components/constellation/pipeline.rs

@@ -356,7 +356,7 @@ impl Pipeline {
     pub fn trigger_mozbrowser_event(&self,
                                      subpage_id: SubpageId,
                                      event: MozBrowserEvent) {
-        assert!(prefs::get_pref("dom.mozbrowser.enabled").as_boolean().unwrap_or(false));
+        assert!(prefs::mozbrowser_enabled());
 
         let event = ConstellationControlMsg::MozBrowserEvent(self.id,
                                                              subpage_id,

components/script/dom/bindings/callback.rs

@@ -164,7 +164,7 @@ impl CallSetup {
     /// Performs the setup needed to make a call.
     #[allow(unrooted_must_root)]
     pub fn new<T: CallbackContainer>(callback: &T, handling: ExceptionHandling) -> CallSetup {
-        let global = global_root_from_object(callback.callback());
+        let global = unsafe { global_root_from_object(callback.callback()) };
         let cx = global.r().get_cx();
 
         let exception_compartment = unsafe {

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

@@ -5,6 +5,7 @@
 # Common codegen classes.
 
 from collections import defaultdict
+from itertools import groupby
 
 import operator
 import re
@@ -1322,31 +1323,23 @@ def getRetvalDeclarationForType(returnType, descriptorProvider):
                     returnType)
 
 
-class MemberCondition:
+def MemberCondition(pref, func):
     """
-    An object representing the condition for a member to actually be
+    A string representing the condition for a member to actually be exposed.
-    exposed.  Any of the arguments can be None.  If not
+    Any of the arguments can be None. If not None, they should have the
-    None, they should have the following types:
+    following types:
 
     pref: The name of the preference.
     func: The name of the function.
     """
-    def __init__(self, pref=None, func=None):
+    assert pref is None or isinstance(pref, str)
-        assert pref is None or isinstance(pref, str)
+    assert func is None or isinstance(func, str)
-        assert func is None or isinstance(func, str)
+    assert func is None or pref is None
-        self.pref = pref
+    if pref:
-
+        return 'Condition::Pref("%s")' % pref
-        def toFuncPtr(val):
+    if func:
-            if val is None:
+        return 'Condition::Func(%s)' % func
-                return "None"
+    return "Condition::Satisfied"
-            return "Some(%s)" % val
-        self.func = toFuncPtr(func)
-
-    def __eq__(self, other):
-        return (self.pref == other.pref and self.func == other.func)
-
-    def __ne__(self, other):
-        return not self.__eq__(other)
 
 
 class PropertyDefiner:
@@ -1390,8 +1383,8 @@ class PropertyDefiner:
             PropertyDefiner.getStringAttr(interfaceMember,
                                           "Func"))
 
-    def generatePrefableArray(self, array, name, specTemplate, specTerminator,
+    def generateGuardedArray(self, array, name, specTemplate, specTerminator,
-                              specType, getCondition, getDataTuple):
+                             specType, getCondition, getDataTuple):
         """
         This method generates our various arrays.
 
@@ -1417,43 +1410,23 @@ class PropertyDefiner:
         # members while still allowing us to define all the members in the smallest
         # number of JSAPI calls.
         assert len(array) != 0
-        # So we won't put a specTerminator at the very front of the list:
-        lastCondition = getCondition(array[0], self.descriptor)
         specs = []
-        currentSpecs = []
         prefableSpecs = []
+        prefableTemplate = '    Guard::new(%s, %s[%d])'
 
-        prefableTemplate = '    Prefable { pref: %s, specs: %s[%d], terminator: %s }'
+        for cond, members in groupby(array, lambda m: getCondition(m, self.descriptor)):
-
+            currentSpecs = [specTemplate % getDataTuple(m) for m in members]
-        def switchToCondition(props, condition):
+            if specTerminator:
-            prefableSpecs.append(prefableTemplate %
+                currentSpecs.append(specTerminator)
-                                 ('Some("%s")' % condition.pref if condition.pref else 'None',
-                                  name + "_specs",
-                                  len(specs),
-                                  'true' if specTerminator else 'false'))
             specs.append("&[\n" + ",\n".join(currentSpecs) + "]\n")
-            del currentSpecs[:]
+            prefableSpecs.append(
-
+                prefableTemplate % (cond, name + "_specs", len(specs) - 1))
-        for member in array:
-            curCondition = getCondition(member, self.descriptor)
-            if lastCondition != curCondition:
-                # Terminate previous list
-                if specTerminator:
-                    currentSpecs.append(specTerminator)
-                # And switch to our new pref
-                switchToCondition(self, lastCondition)
-                lastCondition = curCondition
-            # And the actual spec
-            currentSpecs.append(specTemplate % getDataTuple(member))
-        if specTerminator:
-            currentSpecs.append(specTerminator)
-        switchToCondition(self, lastCondition)
 
         specsArray = ("const %s_specs: &'static [&'static[%s]] = &[\n" +
                       ",\n".join(specs) + "\n" +
                       "];\n") % (name, specType)
 
-        prefArray = ("const %s: &'static [Prefable<%s>] = &[\n" +
+        prefArray = ("const %s: &'static [Guard<&'static [%s]>] = &[\n" +
                      ",\n".join(prefableSpecs) + "\n" +
                      "];\n") % (name, specType)
         return specsArray + prefArray
@@ -1500,7 +1473,7 @@ class MethodDefiner(PropertyDefiner):
                                  "methodInfo": False,
                                  "selfHostedName": "ArrayValues",
                                  "length": 0,
-                                 "condition": MemberCondition()})
+                                 "condition": "Condition::Satisfied"})
 
         isUnforgeableInterface = bool(descriptor.interface.getExtendedAttribute("Unforgeable"))
         if not static and unforgeable == isUnforgeableInterface:
@@ -1551,7 +1524,7 @@ class MethodDefiner(PropertyDefiner):
                         % m["name"][2:], accessor, jitinfo, m["length"], flags, selfHostedName)
             return (str_to_const_array(m["name"]), accessor, jitinfo, m["length"], flags, selfHostedName)
 
-        return self.generatePrefableArray(
+        return self.generateGuardedArray(
             array, name,
             '    JSFunctionSpec {\n'
             '        name: %s as *const u8 as *const libc::c_char,\n'
@@ -1631,7 +1604,7 @@ class AttrDefiner(PropertyDefiner):
             return (str_to_const_array(attr.identifier.name), flags, getter(attr),
                     setter(attr))
 
-        return self.generatePrefableArray(
+        return self.generateGuardedArray(
             array, name,
             '    JSPropertySpec {\n'
             '        name: %s as *const u8 as *const libc::c_char,\n'
@@ -1666,7 +1639,7 @@ class ConstDefiner(PropertyDefiner):
             return (str_to_const_array(const.identifier.name),
                     convertConstIDLValueToJSVal(const.value))
 
-        return self.generatePrefableArray(
+        return self.generateGuardedArray(
             array, name,
             '    ConstantSpec { name: %s, value: %s }',
             None,
@@ -2327,8 +2300,8 @@ def InitUnforgeablePropertiesOnHolder(descriptor, properties):
     """
     unforgeables = []
 
-    defineUnforgeableAttrs = "define_prefable_properties(cx, unforgeable_holder.handle(), %s);"
+    defineUnforgeableAttrs = "define_guarded_properties(cx, unforgeable_holder.handle(), %s);"
-    defineUnforgeableMethods = "define_prefable_methods(cx, unforgeable_holder.handle(), %s);"
+    defineUnforgeableMethods = "define_guarded_methods(cx, unforgeable_holder.handle(), %s);"
 
     unforgeableMembers = [
         (defineUnforgeableAttrs, properties.unforgeable_attrs),
@@ -2560,15 +2533,10 @@ assert!(!prototype_proto.ptr.is_null());""" % getPrototypeProto)]
         properties = {"id": name}
         for arrayName in self.properties.arrayNames():
             array = getattr(self.properties, arrayName)
-            if arrayName == "consts":
+            if array.length():
-                if array.length():
+                properties[arrayName] = array.variableName()
-                    properties[arrayName] = array.variableName()
-                else:
-                    properties[arrayName] = "&[]"
-            elif array.length():
-                properties[arrayName] = "Some(%s)" % array.variableName()
             else:
-                properties[arrayName] = "None"
+                properties[arrayName] = "&[]"
 
         code.append(CGGeneric("""
 let mut prototype = RootedObject::new(cx, ptr::null_mut());
@@ -5563,13 +5531,13 @@ class CGBindingRoot(CGThing):
             'dom::bindings::interface::{InterfaceConstructorBehavior, NonCallbackInterfaceObjectClass}',
             'dom::bindings::interface::{create_callback_interface_object, create_interface_prototype_object}',
             'dom::bindings::interface::{create_named_constructors, create_noncallback_interface_object}',
-            'dom::bindings::interface::{define_prefable_methods, define_prefable_properties}',
+            'dom::bindings::interface::{define_guarded_methods, define_guarded_properties}',
             'dom::bindings::interface::{ConstantSpec, NonNullJSNative}',
             'dom::bindings::interface::ConstantVal::{IntVal, UintVal}',
             'dom::bindings::js::{JS, Root, RootedReference}',
             'dom::bindings::js::{OptionalRootedReference}',
             'dom::bindings::reflector::{Reflectable}',
-            'dom::bindings::utils::{DOMClass, DOMJSClass, Prefable}',
+            'dom::bindings::utils::{DOMClass, DOMJSClass}',
             'dom::bindings::utils::{DOM_PROTO_UNFORGEABLE_HOLDER_SLOT, JSCLASS_DOM_GLOBAL}',
             'dom::bindings::utils::{ProtoOrIfaceArray, create_dom_global}',
             'dom::bindings::utils::{enumerate_global, finalize_global, find_enum_string_index}',
@@ -5593,6 +5561,7 @@ class CGBindingRoot(CGThing):
             'dom::bindings::error::{Fallible, Error, ErrorResult}',
             'dom::bindings::error::Error::JSFailed',
             'dom::bindings::error::throw_dom_exception',
+            'dom::bindings::guard::{Condition, Guard}',
             'dom::bindings::proxyhandler',
             'dom::bindings::proxyhandler::{ensure_expando_object, fill_property_descriptor}',
             'dom::bindings::proxyhandler::{get_expando_object, get_property_descriptor}',

components/script/dom/bindings/global.rs

@@ -302,44 +302,39 @@ impl GlobalRoot {
 
 /// Returns the global object of the realm that the given DOM object's reflector was created in.
 pub fn global_root_from_reflector<T: Reflectable>(reflector: &T) -> GlobalRoot {
-    global_root_from_object(*reflector.reflector().get_jsobject())
+    unsafe { global_root_from_object(*reflector.reflector().get_jsobject()) }
 }
 
 /// Returns the Rust global object from a JS global object.
 #[allow(unrooted_must_root)]
-pub fn global_root_from_global(global: *mut JSObject) -> GlobalRoot {
+unsafe fn global_root_from_global(global: *mut JSObject) -> GlobalRoot {
-    unsafe {
+    assert!(!global.is_null());
-        let clasp = JS_GetClass(global);
+    let clasp = JS_GetClass(global);
-        assert!(((*clasp).flags & (JSCLASS_IS_DOMJSCLASS | JSCLASS_IS_GLOBAL)) != 0);
+    assert!(((*clasp).flags & (JSCLASS_IS_DOMJSCLASS | JSCLASS_IS_GLOBAL)) != 0);
-        match root_from_object(global) {
+    match root_from_object(global) {
-            Ok(window) => return GlobalRoot::Window(window),
+        Ok(window) => return GlobalRoot::Window(window),
-            Err(_) => (),
+        Err(_) => (),
-        }
-
-        match root_from_object(global) {
-            Ok(worker) => return GlobalRoot::Worker(worker),
-            Err(_) => (),
-        }
-
-        panic!("found DOM global that doesn't unwrap to Window or WorkerGlobalScope")
     }
+
+    match root_from_object(global) {
+        Ok(worker) => return GlobalRoot::Worker(worker),
+        Err(_) => (),
+    }
+
+    panic!("found DOM global that doesn't unwrap to Window or WorkerGlobalScope")
 }
 
 /// Returns the global object of the realm that the given JS object was created in.
 #[allow(unrooted_must_root)]
-pub fn global_root_from_object(obj: *mut JSObject) -> GlobalRoot {
+pub unsafe fn global_root_from_object(obj: *mut JSObject) -> GlobalRoot {
-    unsafe {
+    assert!(!obj.is_null());
-        let global = GetGlobalForObjectCrossCompartment(obj);
+    let global = GetGlobalForObjectCrossCompartment(obj);
-        global_root_from_global(global)
+    global_root_from_global(global)
-    }
 }
 
 /// Returns the global object for the given JSContext
 #[allow(unrooted_must_root)]
-pub fn global_root_from_context(cx: *mut JSContext) -> GlobalRoot {
+pub unsafe fn global_root_from_context(cx: *mut JSContext) -> GlobalRoot {
-    unsafe {
+    let global = CurrentGlobalOrNull(cx);
-        let global = CurrentGlobalOrNull(cx);
+    global_root_from_global(global)
-        assert!(!global.is_null());
-        global_root_from_global(global)
-    }
 }

components/script/dom/bindings/guard.rs

@@ -0,0 +1,55 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Machinery to conditionally expose things.
+
+use js::jsapi::{HandleObject, JSContext};
+use util::prefs::get_pref;
+
+/// A container with a condition.
+pub struct Guard<T: Clone + Copy> {
+    condition: Condition,
+    value: T,
+}
+
+impl<T: Clone + Copy> Guard<T> {
+    /// Construct a new guarded value.
+    pub const fn new(condition: Condition, value: T) -> Self {
+        Guard {
+            condition: condition,
+            value: value,
+        }
+    }
+
+    /// Expose the value if the condition is satisfied.
+    ///
+    /// The passed handle is the object on which the value may be exposed.
+    pub unsafe fn expose(&self, cx: *mut JSContext, obj: HandleObject) -> Option<T> {
+        if self.condition.is_satisfied(cx, obj) {
+            Some(self.value)
+        } else {
+            None
+        }
+    }
+}
+
+/// A condition to expose things.
+pub enum Condition {
+    /// The condition is satisfied if the function returns true.
+    Func(unsafe fn(*mut JSContext, HandleObject) -> bool),
+    /// The condition is satisfied if the preference is set.
+    Pref(&'static str),
+    /// The condition is always satisfied.
+    Satisfied,
+}
+
+impl Condition {
+    unsafe fn is_satisfied(&self, cx: *mut JSContext, obj: HandleObject) -> bool {
+        match *self {
+            Condition::Pref(name) => get_pref(name).as_boolean().unwrap_or(false),
+            Condition::Func(f) => f(cx, obj),
+            Condition::Satisfied => true,
+        }
+    }
+}

components/script/dom/bindings/interface.rs

@@ -6,7 +6,8 @@
 
 use dom::bindings::codegen::PrototypeList;
 use dom::bindings::conversions::get_dom_class;
-use dom::bindings::utils::{get_proto_or_iface_array, Prefable};
+use dom::bindings::guard::Guard;
+use dom::bindings::utils::get_proto_or_iface_array;
 use js::error::throw_type_error;
 use js::glue::UncheckedUnwrapObject;
 use js::jsapi::{Class, ClassExtension, ClassSpec, GetGlobalForObjectCrossCompartment};
@@ -66,7 +67,10 @@ pub type NonNullJSNative =
 
 /// Defines constants on `obj`.
 /// Fails on JSAPI failure.
-pub fn define_constants(cx: *mut JSContext, obj: HandleObject, constants: &'static [ConstantSpec]) {
+fn define_constants(
+        cx: *mut JSContext,
+        obj: HandleObject,
+        constants: &[ConstantSpec]) {
     for spec in constants {
         let value = RootedValue::new(cx, spec.get_value());
         unsafe {
@@ -208,18 +212,20 @@ impl InterfaceConstructorBehavior {
 /// Create and define the interface object of a callback interface.
 pub unsafe fn create_callback_interface_object(
         cx: *mut JSContext,
-        receiver: HandleObject,
+        global: HandleObject,
-        constants: &'static [Prefable<ConstantSpec>],
+        constants: &[Guard<&[ConstantSpec]>],
-        name: &'static [u8],
+        name: &[u8],
         rval: MutableHandleObject) {
     assert!(!constants.is_empty());
     rval.set(JS_NewObject(cx, ptr::null()));
     assert!(!rval.ptr.is_null());
-    for prefable in constants {
+    for guard in constants {
-        define_constants(cx, rval.handle(), prefable.specs());
+        if let Some(specs) = guard.expose(cx, rval.handle()) {
+            define_constants(cx, rval.handle(), specs);
+        }
     }
     define_name(cx, rval.handle(), name);
-    define_on_global_object(cx, receiver, name, rval.handle());
+    define_on_global_object(cx, global, name, rval.handle());
 }
 
 /// Create the interface prototype object of a non-callback interface.
@@ -227,9 +233,9 @@ pub unsafe fn create_interface_prototype_object(
         cx: *mut JSContext,
         proto: HandleObject,
         class: &'static JSClass,
-        regular_methods: Option<&'static [Prefable<JSFunctionSpec>]>,
+        regular_methods: &[Guard<&'static [JSFunctionSpec]>],
-        regular_properties: Option<&'static [Prefable<JSPropertySpec>]>,
+        regular_properties: &[Guard<&'static [JSPropertySpec]>],
-        constants: &'static [Prefable<ConstantSpec>],
+        constants: &[Guard<&[ConstantSpec]>],
         rval: MutableHandleObject) {
     create_object(cx, proto, class, regular_methods, regular_properties, constants, rval);
 }
@@ -237,14 +243,14 @@ pub unsafe fn create_interface_prototype_object(
 /// Create and define the interface object of a non-callback interface.
 pub unsafe fn create_noncallback_interface_object(
         cx: *mut JSContext,
-        receiver: HandleObject,
+        global: HandleObject,
         proto: HandleObject,
         class: &'static NonCallbackInterfaceObjectClass,
-        static_methods: Option<&'static [Prefable<JSFunctionSpec>]>,
+        static_methods: &[Guard<&'static [JSFunctionSpec]>],
-        static_properties: Option<&'static [Prefable<JSPropertySpec>]>,
+        static_properties: &[Guard<&'static [JSPropertySpec]>],
-        constants: &'static [Prefable<ConstantSpec>],
+        constants: &[Guard<&[ConstantSpec]>],
         interface_prototype_object: HandleObject,
-        name: &'static [u8],
+        name: &[u8],
         length: u32,
         rval: MutableHandleObject) {
     create_object(cx,
@@ -257,14 +263,14 @@ pub unsafe fn create_noncallback_interface_object(
     assert!(JS_LinkConstructorAndPrototype(cx, rval.handle(), interface_prototype_object));
     define_name(cx, rval.handle(), name);
     define_length(cx, rval.handle(), length);
-    define_on_global_object(cx, receiver, name, rval.handle());
+    define_on_global_object(cx, global, name, rval.handle());
 }
 
 /// Create and define the named constructors of a non-callback interface.
 pub unsafe fn create_named_constructors(
         cx: *mut JSContext,
-        receiver: HandleObject,
+        global: HandleObject,
-        named_constructors: &[(NonNullJSNative, &'static [u8], u32)],
+        named_constructors: &[(NonNullJSNative, &[u8], u32)],
         interface_prototype_object: HandleObject) {
     let mut constructor = RootedObject::new(cx, ptr::null_mut());
 
@@ -288,7 +294,7 @@ pub unsafe fn create_named_constructors(
                                    None,
                                    None));
 
-        define_on_global_object(cx, receiver, name, constructor.handle());
+        define_on_global_object(cx, global, name, constructor.handle());
     }
 }
 
@@ -354,42 +360,46 @@ unsafe fn create_object(
         cx: *mut JSContext,
         proto: HandleObject,
         class: &'static JSClass,
-        methods: Option<&'static [Prefable<JSFunctionSpec>]>,
+        methods: &[Guard<&'static [JSFunctionSpec]>],
-        properties: Option<&'static [Prefable<JSPropertySpec>]>,
+        properties: &[Guard<&'static [JSPropertySpec]>],
-        constants: &'static [Prefable<ConstantSpec>],
+        constants: &[Guard<&[ConstantSpec]>],
         rval: MutableHandleObject) {
     rval.set(JS_NewObjectWithUniqueType(cx, class, proto));
     assert!(!rval.ptr.is_null());
-    if let Some(methods) = methods {
+    define_guarded_methods(cx, rval.handle(), methods);
-        define_prefable_methods(cx, rval.handle(), methods);
+    define_guarded_properties(cx, rval.handle(), properties);
-    }
+    for guard in constants {
-    if let Some(properties) = properties {
+        if let Some(specs) = guard.expose(cx, rval.handle()) {
-        define_prefable_properties(cx, rval.handle(), properties);
+            define_constants(cx, rval.handle(), specs);
-    }
+        }
-    for prefable in constants {
-        define_constants(cx, rval.handle(), prefable.specs());
     }
 }
 
 /// Conditionally define methods on an object.
-pub unsafe fn define_prefable_methods(cx: *mut JSContext,
+pub unsafe fn define_guarded_methods(
-                                      obj: HandleObject,
+        cx: *mut JSContext,
-                                      methods: &'static [Prefable<JSFunctionSpec>]) {
+        obj: HandleObject,
-    for prefable in methods {
+        methods: &[Guard<&'static [JSFunctionSpec]>]) {
-        define_methods(cx, obj, prefable.specs()).unwrap();
+    for guard in methods {
+        if let Some(specs) = guard.expose(cx, obj) {
+            define_methods(cx, obj, specs).unwrap();
+        }
     }
 }
 
 /// Conditionally define properties on an object.
-pub unsafe fn define_prefable_properties(cx: *mut JSContext,
+pub unsafe fn define_guarded_properties(
-                                         obj: HandleObject,
+        cx: *mut JSContext,
-                                         properties: &'static [Prefable<JSPropertySpec>]) {
+        obj: HandleObject,
-    for prefable in properties {
+        properties: &[Guard<&'static [JSPropertySpec]>]) {
-        define_properties(cx, obj, prefable.specs()).unwrap();
+    for guard in properties {
+        if let Some(specs) = guard.expose(cx, obj) {
+            define_properties(cx, obj, specs).unwrap();
+        }
     }
 }
 
-unsafe fn define_name(cx: *mut JSContext, obj: HandleObject, name: &'static [u8]) {
+unsafe fn define_name(cx: *mut JSContext, obj: HandleObject, name: &[u8]) {
     assert!(*name.last().unwrap() == b'\0');
     let name = RootedString::new(
         cx, JS_AtomizeAndPinString(cx, name.as_ptr() as *const libc::c_char));
@@ -413,12 +423,12 @@ unsafe fn define_length(cx: *mut JSContext, obj: HandleObject, length: u32) {
 
 unsafe fn define_on_global_object(
         cx: *mut JSContext,
-        receiver: HandleObject,
+        global: HandleObject,
-        name: &'static [u8],
+        name: &[u8],
         obj: HandleObject) {
     assert!(*name.last().unwrap() == b'\0');
     assert!(JS_DefineProperty1(cx,
-                               receiver,
+                               global,
                                name.as_ptr() as *const libc::c_char,
                                obj,
                                JSPROP_RESOLVING,

components/script/dom/bindings/mod.rs

@@ -133,6 +133,7 @@ pub mod cell;
 pub mod conversions;
 pub mod error;
 pub mod global;
+pub mod guard;
 pub mod inheritance;
 pub mod interface;
 pub mod js;

components/script/dom/bindings/utils.rs

@@ -39,7 +39,6 @@ use std::ffi::CString;
 use std::os::raw::c_void;
 use std::ptr;
 use std::slice;
-use util::prefs;
 
 /// Proxy handler for a WindowProxy.
 pub struct WindowProxyHandler(pub *const libc::c_void);
@@ -550,31 +549,3 @@ unsafe extern "C" fn instance_class_has_proto_at_depth(clasp: *const js::jsapi::
 pub const DOM_CALLBACKS: DOMCallbacks = DOMCallbacks {
     instanceClassMatchesProto: Some(instance_class_has_proto_at_depth),
 };
-
-/// A container around JS member specifications that are conditionally enabled.
-pub struct Prefable<T: 'static> {
-    /// If present, the name of the preference used to conditionally enable these specs.
-    pub pref: Option<&'static str>,
-    /// The underlying slice of specifications.
-    pub specs: &'static [T],
-    /// Whether the specifications contain special terminating entries that should be
-    /// included or not.
-    pub terminator: bool,
-}
-
-impl<T> Prefable<T> {
-    /// Retrieve the slice represented by this container, unless the condition
-    /// guarding it is false.
-    pub fn specs(&self) -> &'static [T] {
-        if let Some(pref) = self.pref {
-            if !prefs::get_pref(pref).as_boolean().unwrap_or(false) {
-                return if self.terminator {
-                    &self.specs[self.specs.len() - 1..]
-                } else {
-                    &[]
-                };
-            }
-        }
-        self.specs
-    }
-}

components/script/dom/document.rs

@@ -56,7 +56,7 @@ use dom::htmlembedelement::HTMLEmbedElement;
 use dom::htmlformelement::HTMLFormElement;
 use dom::htmlheadelement::HTMLHeadElement;
 use dom::htmlhtmlelement::HTMLHtmlElement;
-use dom::htmliframeelement::{self, HTMLIFrameElement};
+use dom::htmliframeelement::HTMLIFrameElement;
 use dom::htmlimageelement::HTMLImageElement;
 use dom::htmllinkelement::HTMLLinkElement;
 use dom::htmlmetaelement::HTMLMetaElement;
@@ -127,6 +127,7 @@ use task_source::dom_manipulation::DOMManipulationTask;
 use time;
 use url::Url;
 use url::percent_encoding::percent_decode;
+use util::prefs::mozbrowser_enabled;
 use util::str::{split_html_space_chars, str_join};
 
 #[derive(JSTraceable, PartialEq, HeapSizeOf)]
@@ -1261,7 +1262,7 @@ impl Document {
     }
 
     pub fn trigger_mozbrowser_event(&self, event: MozBrowserEvent) {
-        if htmliframeelement::mozbrowser_enabled() {
+        if mozbrowser_enabled() {
             if let Some((containing_pipeline_id, subpage_id)) = self.window.parent_info() {
                 let event = ConstellationMsg::MozBrowserEvent(containing_pipeline_id,
                                                               subpage_id,

components/script/dom/htmliframeelement.rs

@@ -42,13 +42,9 @@ use std::cell::Cell;
 use string_cache::Atom;
 use style::context::ReflowGoal;
 use url::Url;
-use util::prefs;
+use util::prefs::mozbrowser_enabled;
 use util::str::LengthOrPercentageOrAuto;
 
-pub fn mozbrowser_enabled() -> bool {
-    prefs::get_pref("dom.mozbrowser.enabled").as_boolean().unwrap_or(false)
-}
-
 #[derive(HeapSizeOf)]
 enum SandboxAllowance {
     AllowNothing = 0x00,
@@ -439,29 +435,16 @@ impl HTMLIFrameElementMethods for HTMLIFrameElement {
     // Experimental mozbrowser implementation is based on the webidl
     // present in the gecko source tree, and the documentation here:
     // https://developer.mozilla.org/en-US/docs/Web/API/Using_the_Browser_API
-
-    // TODO(gw): Use experimental codegen when it is available to avoid
-    // exposing these APIs. See https://github.com/servo/servo/issues/5264.
-
     // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#attr-mozbrowser
     fn Mozbrowser(&self) -> bool {
-        // We don't want to allow mozbrowser iframes within iframes
+        let element = self.upcast::<Element>();
-        let is_root_pipeline = window_from_node(self).parent_info().is_none();
+        element.has_attribute(&atom!("mozbrowser"))
-        if mozbrowser_enabled() && is_root_pipeline {
-            let element = self.upcast::<Element>();
-            element.has_attribute(&atom!("mozbrowser"))
-        } else {
-            false
-        }
     }
 
     // https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#attr-mozbrowser
-    fn SetMozbrowser(&self, value: bool) -> ErrorResult {
+    fn SetMozbrowser(&self, value: bool) {
-        if mozbrowser_enabled() {
+        let element = self.upcast::<Element>();
-            let element = self.upcast::<Element>();
+        element.set_bool_attribute(&atom!("mozbrowser"), value);
-            element.set_bool_attribute(&atom!("mozbrowser"), value);
-        }
-        Ok(())
     }
 
     // https://developer.mozilla.org/en-US/docs/Web/API/HTMLIFrameElement/goBack

components/script/dom/testbinding.rs

@@ -24,7 +24,7 @@ use dom::bindings::str::{ByteString, DOMString, USVString};
 use dom::bindings::weakref::MutableWeakRef;
 use dom::blob::{Blob, DataSlice};
 use dom::url::URL;
-use js::jsapi::{HandleValue, JSContext, JSObject};
+use js::jsapi::{HandleObject, HandleValue, JSContext, JSObject};
 use js::jsval::{JSVal, NullValue};
 use std::borrow::ToOwned;
 use std::ptr;
@@ -567,6 +567,10 @@ impl TestBindingMethods for TestBinding {
     fn PrefControlledAttributeEnabled(&self) -> bool { false }
     fn PrefControlledMethodDisabled(&self) {}
     fn PrefControlledMethodEnabled(&self) {}
+    fn FuncControlledAttributeDisabled(&self) -> bool { false }
+    fn FuncControlledAttributeEnabled(&self) -> bool { false }
+    fn FuncControlledMethodDisabled(&self) {}
+    fn FuncControlledMethodEnabled(&self) {}
 }
 
 impl TestBinding {
@@ -577,4 +581,14 @@ impl TestBinding {
     pub fn PrefControlledStaticAttributeEnabled(_: GlobalRef) -> bool { false }
     pub fn PrefControlledStaticMethodDisabled(_: GlobalRef) {}
     pub fn PrefControlledStaticMethodEnabled(_: GlobalRef) {}
+    pub fn FuncControlledStaticAttributeDisabled(_: GlobalRef) -> bool { false }
+    pub fn FuncControlledStaticAttributeEnabled(_: GlobalRef) -> bool { false }
+    pub fn FuncControlledStaticMethodDisabled(_: GlobalRef) {}
+    pub fn FuncControlledStaticMethodEnabled(_: GlobalRef) {}
+}
+
+#[allow(unsafe_code)]
+impl TestBinding {
+    pub unsafe fn condition_satisfied(_: *mut JSContext, _: HandleObject) -> bool { true }
+    pub unsafe fn condition_unsatisfied(_: *mut JSContext, _: HandleObject) -> bool { false }
 }

components/script/dom/webidls/HTMLIFrameElement.webidl

@@ -32,8 +32,8 @@ partial interface HTMLIFrameElement {
 };
 
 partial interface HTMLIFrameElement {
-  [ChromeOnly,SetterThrows,Pref="dom.mozbrowser.enabled"]
+    [Func="Window::global_is_mozbrowser"]
-           attribute boolean mozbrowser;
+    attribute boolean mozbrowser;
 };
 
 HTMLIFrameElement implements BrowserElement;

components/script/dom/webidls/TestBinding.webidl

@@ -433,4 +433,26 @@ interface TestBinding {
   static void prefControlledStaticMethodEnabled();
   [Pref="dom.testbinding.prefcontrolled2.enabled"]
   const unsigned short prefControlledConstEnabled = 0;
+
+  [Func="TestBinding::condition_unsatisfied"]
+  readonly attribute boolean funcControlledAttributeDisabled;
+  [Func="TestBinding::condition_unsatisfied"]
+  static readonly attribute boolean funcControlledStaticAttributeDisabled;
+  [Func="TestBinding::condition_unsatisfied"]
+  void funcControlledMethodDisabled();
+  [Func="TestBinding::condition_unsatisfied"]
+  static void funcControlledStaticMethodDisabled();
+  [Func="TestBinding::condition_unsatisfied"]
+  const unsigned short funcControlledConstDisabled = 0;
+
+  [Func="TestBinding::condition_satisfied"]
+  readonly attribute boolean funcControlledAttributeEnabled;
+  [Func="TestBinding::condition_satisfied"]
+  static readonly attribute boolean funcControlledStaticAttributeEnabled;
+  [Func="TestBinding::condition_satisfied"]
+  void funcControlledMethodEnabled();
+  [Func="TestBinding::condition_satisfied"]
+  static void funcControlledStaticMethodEnabled();
+  [Func="TestBinding::condition_satisfied"]
+  const unsigned short funcControlledConstEnabled = 0;
 };

components/script/dom/window.rs

@@ -14,7 +14,7 @@ use dom::bindings::codegen::Bindings::FunctionBinding::Function;
 use dom::bindings::codegen::Bindings::WindowBinding::{ScrollBehavior, ScrollToOptions};
 use dom::bindings::codegen::Bindings::WindowBinding::{self, FrameRequestCallback, WindowMethods};
 use dom::bindings::error::{Error, Fallible, report_pending_exception};
-use dom::bindings::global::GlobalRef;
+use dom::bindings::global::{GlobalRef, global_root_from_object};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::{JS, MutNullableHeap, Root};
 use dom::bindings::num::Finite;
@@ -37,9 +37,8 @@ use dom::storage::Storage;
 use euclid::{Point2D, Rect, Size2D};
 use gfx_traits::LayerId;
 use ipc_channel::ipc::{self, IpcSender};
-use js::jsapi::{Evaluate2, MutableHandleValue};
+use js::jsapi::{Evaluate2, HandleObject, HandleValue, JSAutoCompartment, JSContext};
-use js::jsapi::{HandleValue, JSContext};
+use js::jsapi::{JS_GetRuntime, JS_GC, MutableHandleValue, SetWindowProxy};
-use js::jsapi::{JSAutoCompartment, JS_GC, JS_GetRuntime, SetWindowProxy};
 use js::rust::CompileOptionsWrapper;
 use js::rust::Runtime;
 use layout_interface::{ContentBoxResponse, ContentBoxesResponse, ResolvedStyleResponse, ScriptReflow};
@@ -93,6 +92,7 @@ use timers::{IsInterval, OneshotTimerCallback, OneshotTimerHandle, OneshotTimers
 use tinyfiledialogs::{self, MessageBoxIcon};
 use url::Url;
 use util::geometry::{self, MAX_RECT};
+use util::prefs::mozbrowser_enabled;
 use util::str::HTML_SPACE_CHARACTERS;
 use util::{breakpoint, opts};
 use webdriver_handlers::jsval_to_webdriver;
@@ -1437,6 +1437,19 @@ impl Window {
             context.active_window()
         })
     }
+
+    /// Returns whether mozbrowser is enabled and `obj` has been created
+    /// in a top-level `Window` global.
+    #[allow(unsafe_code)]
+    pub unsafe fn global_is_mozbrowser(_: *mut JSContext, obj: HandleObject) -> bool {
+        if !mozbrowser_enabled() {
+            return false;
+        }
+        match global_root_from_object(obj.get()).r() {
+            GlobalRef::Window(window) => window.parent_info().is_none(),
+            _ => false,
+        }
+    }
 }
 
 impl Window {

components/script/dom/xmlhttprequest.rs

@@ -62,7 +62,7 @@ use string_cache::Atom;
 use time;
 use timers::{OneshotTimerCallback, OneshotTimerHandle};
 use url::{Url, Position};
-use util::prefs;
+use util::prefs::mozbrowser_enabled;
 
 #[derive(JSTraceable, PartialEq, Copy, Clone, HeapSizeOf)]
 enum XMLHttpRequestState {
@@ -884,7 +884,7 @@ impl XMLHttpRequest {
             // story. See https://github.com/servo/servo/issues/9582
             if let GlobalRoot::Window(win) = self.global() {
                 let is_root_pipeline = win.parent_info().is_none();
-                let is_mozbrowser_enabled = prefs::get_pref("dom.mozbrowser.enabled").as_boolean().unwrap_or(false);
+                let is_mozbrowser_enabled = mozbrowser_enabled();
                 is_root_pipeline && is_mozbrowser_enabled
             } else {
                 false

components/util/prefs.rs

@@ -243,3 +243,7 @@ pub fn reset_all_prefs() {
         reset_pref(name);
     }
 }
+
+pub fn mozbrowser_enabled() -> bool {
+    get_pref("dom.mozbrowser.enabled").as_boolean().unwrap_or(false)
+}

tests/wpt/mozilla/tests/mozilla/interface_member_exposed.html

@@ -19,10 +19,15 @@ function test_member(name, enabled, target) {
 }
 
 var members = [
+  'funcControlledAttribute',
+  'funcControlledMethod',
   'prefControlledAttribute',
   'prefControlledMethod'
 ];
 var staticMembers = [
+  'funcControlledStaticAttribute',
+  'funcControlledStaticMethod',
+  'funcControlledConst',
   'prefControlledStaticAttribute',
   'prefControlledStaticMethod',
   'prefControlledConst'