Strong html

tools/dom/src/EventStreamProvider.dart

Index: tools/dom/src/EventStreamProvider.dart
diff --git a/tools/dom/src/EventStreamProvider.dart b/tools/dom/src/EventStreamProvider.dart
index 3b41f51821892c5817fb99dd891d2ecc94af24e2..76bed572735ed5c939c762b06c5cc56276a9e3e0 100644
--- a/tools/dom/src/EventStreamProvider.dart
+++ b/tools/dom/src/EventStreamProvider.dart
@@ -34,7 +34,7 @@ class EventStreamProvider<T extends Event> {
    * [addEventListener](http://docs.webplatform.org/wiki/dom/methods/addEventListener)
    */
   Stream<T> forTarget(EventTarget e, {bool useCapture: false}) =>
-    new _EventStream(e, _eventType, useCapture);
+    new _EventStream<T>(e, _eventType, useCapture);
 
   /**
    * Gets an [ElementEventStream] for this event type, on the specified element.
@@ -58,7 +58,7 @@ class EventStreamProvider<T extends Event> {
    * [addEventListener](http://docs.webplatform.org/wiki/dom/methods/addEventListener)
    */
   ElementStream<T> forElement(Element e, {bool useCapture: false}) {
-    return new _ElementEventStreamImpl(e, _eventType, useCapture);
+    return new _ElementEventStreamImpl<T>(e, _eventType, useCapture);
   }
 
   /**
@@ -129,8 +129,8 @@ class _EventStream<T extends Event> extends Stream<T> {
   _EventStream(this._target, this._eventType, this._useCapture);
 
   // DOM events are inherently multi-subscribers.
-  Stream<T> asBroadcastStream({void onListen(StreamSubscription subscription),
-                               void onCancel(StreamSubscription subscription)})
+  Stream<T> asBroadcastStream({void onListen(StreamSubscription<T> subscription),
+                               void onCancel(StreamSubscription<T> subscription)})
       => this;
   bool get isBroadcast => true;
 
@@ -144,6 +144,11 @@ class _EventStream<T extends Event> extends Stream<T> {
   }
 }
 
+bool _matchesWithAncestors(Event event, String selector) {
+  var target = event.target;
+  return target is Element ? target.matchesWithAncestors(selector) : false;
+}
+
 /**
  * Adapter for exposing DOM Element events as streams, while also allowing
  * event delegation.
@@ -154,7 +159,7 @@ class _ElementEventStreamImpl<T extends Event> extends _EventStream<T>
       super(target, eventType, useCapture);
 
   Stream<T> matches(String selector) => this.where(
-      (event) => event.target.matchesWithAncestors(selector)).map((e) {
+      (event) => _matchesWithAncestors(event, selector)).map((e) {
         e._selector = selector;
         return e;
       });
@@ -178,7 +183,7 @@ class _ElementListEventStreamImpl<T extends Event> extends Stream<T>
       this._targetList, this._eventType, this._useCapture);
 
   Stream<T> matches(String selector) => this.where(
-      (event) => event.target.matchesWithAncestors(selector)).map((e) {
+      (event) => _matchesWithAncestors(event, selector)).map((e) {
         e._selector = selector;
         return e;
       });
@@ -188,37 +193,46 @@ class _ElementListEventStreamImpl<T extends Event> extends Stream<T>
       { Function onError,
         void onDone(),
         bool cancelOnError}) {
-    var pool = new _StreamPool.broadcast();
+    var pool = new _StreamPool<T>.broadcast();
     for (var target in _targetList) {
-      pool.add(new _EventStream(target, _eventType, _useCapture));
+      pool.add(new _EventStream<T>(target, _eventType, _useCapture));
     }
     return pool.stream.listen(onData, onError: onError, onDone: onDone,
           cancelOnError: cancelOnError);
   }
 
   StreamSubscription<T> capture(void onData(T event)) {
-    var pool = new _StreamPool.broadcast();
+    var pool = new _StreamPool<T>.broadcast();
     for (var target in _targetList) {
-      pool.add(new _EventStream(target, _eventType, true));
+      pool.add(new _EventStream<T>(target, _eventType, true));
     }
     return pool.stream.listen(onData);
   }
 
-  Stream<T> asBroadcastStream({void onListen(StreamSubscription subscription),
-                               void onCancel(StreamSubscription subscription)})
+  Stream<T> asBroadcastStream({void onListen(StreamSubscription<T> subscription),
+                               void onCancel(StreamSubscription<T> subscription)})
       => this;
   bool get isBroadcast => true;
 }
 
+// We would like this to just be EventListener<T> but that typdef cannot
+// use generics until dartbug/26276 is fixed.
+typedef _EventListener<T extends Event>(T event);
+
 class _EventStreamSubscription<T extends Event> extends StreamSubscription<T> {
   int _pauseCount = 0;
   EventTarget _target;
   final String _eventType;
-  var _onData;
+  EventListener _onData;
   final bool _useCapture;
 
-  _EventStreamSubscription(this._target, this._eventType, onData,
-      this._useCapture) : _onData = _wrapZone(onData) {
+  // TODO(jacobr): for full strong mode correctness we should write
+  // _onData = onData == null ? null : _wrapZone/*<Event, dynamic>*/((e) => onData(e as T))
+  // but that breaks 114 co19 tests as well as multiple html tests as it is reasonable
+  // to pass the wrong type of event object to an event listener as part of a
+  // test.
+  _EventStreamSubscription(this._target, this._eventType, void onData(T event),
+      this._useCapture) : _onData = _wrapZone/*<Event, dynamic>*/(onData) {

[Jacob, 2016/04/19 17:12:29]

This is the most problematic of the dart:html changes.
I tried to change this to _wrapZone/*<Event, dynamic>*/((e) => onData(e as T))
but it broke way too many tests as it is too hard and sometimes impossible to
pass correct event subtypes to event listeners for tests.
Over 100 co19 tests broke because of this and I would expect many more could as
well.
The other option to fix this would be to make all event streams in the dom just
be EventStreamSubscription<Event> but that would be breaking change and lose
useful documentation information we currently provide.

[Leaf, 2016/04/19 23:01:14]

Do tests that do this screwy stuff pass in an onData that is dynamic -> void? 
If so, you could possibly force a dcall here so that you only fail if the even
is the wrong type and onData doesn't accept dynamic?  If I'm understanding the
problem correctly.

     _tryResume();
   }
 
@@ -240,8 +254,7 @@ class _EventStreamSubscription<T extends Event> extends StreamSubscription<T> {
     }
     // Remove current event listener.
     _unlisten();
-
-    _onData = _wrapZone(handleData);
+    _onData = _wrapZone/*<Event, dynamic>*/(handleData);
     _tryResume();
   }
 
@@ -320,8 +333,8 @@ class _CustomEventStreamImpl<T extends Event> extends Stream<T>
         onDone: onDone, cancelOnError: cancelOnError);
   }
 
-  Stream<T> asBroadcastStream({void onListen(StreamSubscription subscription),
-                               void onCancel(StreamSubscription subscription)})
+  Stream<T> asBroadcastStream({void onListen(StreamSubscription<T> subscription),
+                               void onCancel(StreamSubscription<T> subscription)})
       => _streamController.stream;
 
   bool get isBroadcast => true;
@@ -412,16 +425,16 @@ class _CustomEventStreamProvider<T extends Event>
   const _CustomEventStreamProvider(this._eventTypeGetter);
 
   Stream<T> forTarget(EventTarget e, {bool useCapture: false}) {
-    return new _EventStream(e, _eventTypeGetter(e), useCapture);
+    return new _EventStream<T>(e, _eventTypeGetter(e), useCapture);
   }
 
   ElementStream<T> forElement(Element e, {bool useCapture: false}) {
-    return new _ElementEventStreamImpl(e, _eventTypeGetter(e), useCapture);
+    return new _ElementEventStreamImpl<T>(e, _eventTypeGetter(e), useCapture);
   }
 
   ElementStream<T> _forElementList(ElementList e,
       {bool useCapture: false}) {
-    return new _ElementListEventStreamImpl(e, _eventTypeGetter(e), useCapture);
+    return new _ElementListEventStreamImpl<T>(e, _eventTypeGetter(e), useCapture);
   }
 
   String getEventType(EventTarget target) {