5 files changed, 53 insertions, 8 deletions
diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index f418a1ba569..73d9f7f3ed0 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -1334,8 +1334,11 @@ def MemberCondition(pref, func):
     """
     assert pref is None or isinstance(pref, str)
     assert func is None or isinstance(func, str)
+    assert func is None or pref is None
     if pref:
         return 'Condition::Pref("%s")' % pref
+    if func:
+        return 'Condition::Func(%s)' % func
     return "Condition::Satisfied"
 
 
diff --git a/components/script/dom/bindings/guard.rs b/components/script/dom/bindings/guard.rs
index 15b7c418a31..40faebbd4f2 100644
--- a/components/script/dom/bindings/guard.rs
+++ b/components/script/dom/bindings/guard.rs
@@ -4,6 +4,7 @@
 
 //! Machinery to conditionally expose things.
 
+use js::jsapi::{HandleObject, JSContext};
 use util::prefs::get_pref;
 
 /// A container with a condition.
@@ -22,8 +23,10 @@ impl<T: Clone + Copy> Guard<T> {
     }
 
     /// Expose the value if the condition is satisfied.
-    pub fn expose(&self) -> Option<T> {
-        if self.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
@@ -33,6 +36,8 @@ impl<T: Clone + Copy> Guard<T> {
 
 /// 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.
@@ -40,9 +45,10 @@ pub enum Condition {
 }
 
 impl Condition {
-    fn is_satisfied(&self) -> bool {
+    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,
         }
     }
diff --git a/components/script/dom/bindings/interface.rs b/components/script/dom/bindings/interface.rs
index 371e70372ac..590e57ba8e0 100644
--- a/components/script/dom/bindings/interface.rs
+++ b/components/script/dom/bindings/interface.rs
@@ -220,7 +220,7 @@ pub unsafe fn create_callback_interface_object(
     rval.set(JS_NewObject(cx, ptr::null()));
     assert!(!rval.ptr.is_null());
     for guard in constants {
-        if let Some(specs) = guard.expose() {
+        if let Some(specs) = guard.expose(cx, rval.handle()) {
             define_constants(cx, rval.handle(), specs);
         }
     }
@@ -369,7 +369,7 @@ unsafe fn create_object(
     define_guarded_methods(cx, rval.handle(), methods);
     define_guarded_properties(cx, rval.handle(), properties);
     for guard in constants {
-        if let Some(specs) = guard.expose() {
+        if let Some(specs) = guard.expose(cx, rval.handle()) {
             define_constants(cx, rval.handle(), specs);
         }
     }
@@ -381,7 +381,7 @@ pub unsafe fn define_guarded_methods(
         obj: HandleObject,
         methods: &[Guard<&'static [JSFunctionSpec]>]) {
     for guard in methods {
-        if let Some(specs) = guard.expose() {
+        if let Some(specs) = guard.expose(cx, obj) {
             define_methods(cx, obj, specs).unwrap();
         }
     }
@@ -393,7 +393,7 @@ pub unsafe fn define_guarded_properties(
         obj: HandleObject,
         properties: &[Guard<&'static [JSPropertySpec]>]) {
     for guard in properties {
-        if let Some(specs) = guard.expose() {
+        if let Some(specs) = guard.expose(cx, obj) {
             define_properties(cx, obj, specs).unwrap();
         }
     }
diff --git a/components/script/dom/testbinding.rs b/components/script/dom/testbinding.rs
index faf53596ecc..5ff0e0bd272 100644
--- a/components/script/dom/testbinding.rs
+++ b/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 }
 }
diff --git a/components/script/dom/webidls/TestBinding.webidl b/components/script/dom/webidls/TestBinding.webidl
index 6706ccfdaa9..cdfb9fd18ae 100644
--- a/components/script/dom/webidls/TestBinding.webidl
+++ b/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;
 };