Move html events generation to domimpl.

lib/dom/src/native_EventsImplementation.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class EventsImplementation implements html.Events {
+
+  final EventTarget _ptr;
+
+  final Map<String, html.EventListenerList> _listenerMap;
+
+  EventsImplementation(this._ptr) : _listenerMap = <html.EventListenerList>{};
+
+  html.EventListenerList operator [](String type) => _get(type);
+
+  html.EventListenerList _get(String type) {
+    return _listenerMap.putIfAbsent(type,
+      () => new EventListenerListImplementation(_ptr, type));
+  }
+}
+
+class EventListenerWrapper {
+  final html.EventListener raw;
+  final Function wrapped;
+  final bool useCapture;
+  EventListenerWrapper(this.raw, this.wrapped, this.useCapture);
+}
+
+class EventListenerListImplementation implements html.EventListenerList {
+  final EventTarget _ptr;
+  final String _type;
+  List<EventListenerWrapper> _wrappers;
+
+  EventListenerListImplementation(this._ptr, this._type)
+    // TODO(jacobr): switch to <EventListenerWrapper>[] when the VM allow it.
+    : _wrappers = new List<EventListenerWrapper>();
+
+  html.EventListenerList add(html.EventListener listener, [bool useCapture = false]) {
+    _add(listener, useCapture);
+    return this;
+  }
+
+  html.EventListenerList remove(html.EventListener listener, [bool useCapture = false]) {
+    _remove(listener, useCapture);
+    return this;
+  }
+
+  bool dispatch(html.Event evt) {
+    // TODO(jacobr): what is the correct behavior here. We could alternately
+    // force the event to have the expected type.
+    assert(evt.type == _type);
+    return _ptr.dispatchEvent(html.unwrap_internal(evt));
+  }
+
+  void _add(html.EventListener listener, bool useCapture) {
+    _ptr.addEventListener(_type,
+                          _findOrAddWrapper(listener, useCapture),
+                          useCapture);
+  }
+
+  void _remove(html.EventListener listener, bool useCapture) {
+    Function wrapper = _removeWrapper(listener, useCapture);
+    if (wrapper !== null) {
+      _ptr.removeEventListener(_type, wrapper, useCapture);
+    }
+  }
+
+  Function _removeWrapper(html.EventListener listener, bool useCapture) {
+    if (_wrappers === null) {
+      return null;
+    }
+    for (int i = 0; i < _wrappers.length; i++) {
+      EventListenerWrapper wrapper = _wrappers[i];
+      if (wrapper.raw === listener && wrapper.useCapture == useCapture) {
+        // Order doesn't matter so we swap with the last element instead of
+        // performing a more expensive remove from the middle of the list.
+        if (i + 1 != _wrappers.length) {
+          _wrappers[i] = _wrappers.removeLast();
+        } else {
+          _wrappers.removeLast();
+        }
+        return wrapper.wrapped;
+      }
+    }
+    return null;
+  }
+
+  Function _findOrAddWrapper(html.EventListener listener, bool useCapture) {
+    if (_wrappers === null) {
+      _wrappers = <EventListenerWrapper>[];
+    } else {
+      for (EventListenerWrapper wrapper in _wrappers) {
+        if (wrapper.raw === listener && wrapper.useCapture == useCapture) {
+          return wrapper.wrapped;
+        }
+      }
+    }
+    final wrapped = (e) { listener(html.wrap_internal(e)); };
+    _wrappers.add(new EventListenerWrapper(listener, wrapped, useCapture));
+    return wrapped;
+  }
+}