Auto merge of #13292 - creativcoder:extendable, r=jdm

Implement ExtendableEvent as base type for ServiceWorker events

<!-- Please describe your changes on the following line: -->
r? @jdm

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

<!-- Either: -->
- [X] These changes do not require tests because refactor

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/13292)
<!-- Reviewable:end -->

1 files changed, 68 insertions, 0 deletions

diff --git a/components/script/dom/extendableevent.rs b/components/script/dom/extendableevent.rs
new file mode 100644
index 00000000000..76756b40c71
--- /dev/null
+++ b/components/script/dom/extendableevent.rs
@@ -0,0 +1,68 @@
+/* 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/. */
+
+use dom::bindings::codegen::Bindings::EventBinding::EventMethods;
+use dom::bindings::codegen::Bindings::ExtendableEventBinding;
+use dom::bindings::error::{Error, ErrorResult, Fallible};
+use dom::bindings::global::GlobalRef;
+use dom::bindings::inheritance::Castable;
+use dom::bindings::js::Root;
+use dom::bindings::reflector::reflect_dom_object;
+use dom::bindings::str::DOMString;
+use dom::event::Event;
+use js::jsapi::{HandleValue, JSContext};
+use string_cache::Atom;
+
+// https://w3c.github.io/ServiceWorker/#extendable-event
+#[dom_struct]
+pub struct ExtendableEvent {
+    event: Event,
+    extensions_allowed: bool
+}
+
+impl ExtendableEvent {
+    pub fn new_inherited() -> ExtendableEvent {
+        ExtendableEvent {
+            event: Event::new_inherited(),
+            extensions_allowed: true
+        }
+    }
+    pub fn new(global: GlobalRef,
+               type_: Atom,
+               bubbles: bool,
+               cancelable: bool)
+               -> Root<ExtendableEvent> {
+        let ev = reflect_dom_object(box ExtendableEvent::new_inherited(), global, ExtendableEventBinding::Wrap);
+        {
+            let event = ev.upcast::<Event>();
+            event.init_event(type_, bubbles, cancelable);
+        }
+        ev
+    }
+
+    pub fn Constructor(global: GlobalRef,
+                       type_: DOMString,
+                       init: &ExtendableEventBinding::ExtendableEventInit) -> Fallible<Root<ExtendableEvent>> {
+        Ok(ExtendableEvent::new(global,
+                                Atom::from(type_),
+                                init.parent.bubbles,
+                                init.parent.cancelable))
+    }
+
+    // https://w3c.github.io/ServiceWorker/#wait-until-method
+    pub fn WaitUntil(&self, _cx: *mut JSContext, val: HandleValue) -> ErrorResult {
+        // Step 1
+        if !self.extensions_allowed {
+            return Err(Error::InvalidState);
+        }
+        // Step 2
+        // TODO add a extended_promises array to enqueue the `val`
+        Ok(())
+    }
+
+    // https://dom.spec.whatwg.org/#dom-event-istrusted
+    pub fn IsTrusted(&self) -> bool {
+        self.event.IsTrusted()
+    }
+}