[add] NativeEventEmitter export

Export NativeEventEmitter and provide React Native's implementation.

package.json

@@ -63,7 +63,9 @@
   ],
   "lint-staged": {
     "packages/react-native-web/src/index.js": [
-      "node ./scripts/babel/createModuleMap.js"
+      "node ./scripts/babel/createModuleMap.js",
+      "prettier --write ./packages/babel-plugin-react-native-web/src/moduleMap.js",
+      "git add ./packages/babel-plugin-react-native-web/src/moduleMap.js"
     ],
     "**/*.js": [
       "prettier --write",

packages/babel-plugin-react-native-web/src/moduleMap.js

@@ -27,6 +27,7 @@ module.exports = {
   Linking: true,
   ListView: true,
   Modal: true,
+  NativeEventEmitter: true,
   NativeModules: true,
   NetInfo: true,
   PanResponder: true,

packages/react-native-web/src/exports/NativeEventEmitter/index.js

@@ -0,0 +1,11 @@
+/**
+ * Copyright (c) 2016-present, Nicolas Gallagher.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import NativeEventEmitter from '../../vendor/react-native/NativeEventEmitter';
+export default NativeEventEmitter;

packages/react-native-web/src/index.js

@@ -23,6 +23,7 @@ import Keyboard from './exports/Keyboard';
 import InteractionManager from './exports/InteractionManager';
 import LayoutAnimation from './exports/LayoutAnimation';
 import Linking from './exports/Linking';
+import NativeEventEmitter from './exports/NativeEventEmitter';
 import NetInfo from './exports/NetInfo';
 import PanResponder from './exports/PanResponder';
 import PixelRatio from './exports/PixelRatio';
@@ -93,6 +94,7 @@ export {
   Keyboard,
   LayoutAnimation,
   Linking,
+  NativeEventEmitter,
   NetInfo,
   PanResponder,
   PixelRatio,
@@ -162,6 +164,7 @@ const ReactNative = {
   Keyboard,
   LayoutAnimation,
   Linking,
+  NativeEventEmitter,
   NetInfo,
   PanResponder,
   PixelRatio,

packages/react-native-web/src/vendor/react-native/Animated/NativeAnimatedHelper.js

@@ -11,7 +11,7 @@
 
 import invariant from 'fbjs/lib/invariant';
 import NativeModules from '../../../exports/NativeModules';
-import NativeEventEmitter from '../../../modules/NativeEventEmitter';
+import NativeEventEmitter from '../NativeEventEmitter';
 
 import type {AnimationConfig} from './animations/Animation';
 import type {EventConfig} from './AnimatedEvent';

packages/react-native-web/src/vendor/react-native/NativeEventEmitter/index.js

@@ -0,0 +1,67 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @providesModule NativeEventEmitter
+ * @flow
+ */
+'use strict';
+
+import EventEmitter from '../emitter/EventEmitter';
+import Platform from '../../../exports/Platform';
+
+import invariant from 'fbjs/lib/invariant';
+
+import type EmitterSubscription from '../emitter/EmitterSubscription';
+
+type NativeModule = {
+  +addListener: (eventType: string) => void,
+  +removeListeners: (count: number) => void,
+};
+
+/**
+ * Abstract base class for implementing event-emitting modules. This implements
+ * a subset of the standard EventEmitter node module API.
+ */
+class NativeEventEmitter extends EventEmitter {
+  _nativeModule: ?NativeModule;
+
+  constructor(nativeModule: ?NativeModule) {
+    super();
+    if (Platform.OS === 'ios') {
+      invariant(nativeModule, 'Native module cannot be null.');
+      this._nativeModule = nativeModule;
+    }
+  }
+
+  addListener(
+    eventType: string,
+    listener: Function,
+    context: ?Object,
+  ): EmitterSubscription {
+    if (this._nativeModule != null) {
+      this._nativeModule.addListener(eventType);
+    }
+    return super.addListener(eventType, listener, context);
+  }
+
+  removeAllListeners(eventType: string) {
+    invariant(eventType, 'eventType argument is required.');
+    const count = this.listeners(eventType).length;
+    if (this._nativeModule != null) {
+      this._nativeModule.removeListeners(count);
+    }
+    super.removeAllListeners(eventType);
+  }
+
+  removeSubscription(subscription: EmitterSubscription) {
+    if (this._nativeModule != null) {
+      this._nativeModule.removeListeners(1);
+    }
+    super.removeSubscription(subscription);
+  }
+}
+
+export default NativeEventEmitter;

packages/react-native-web/src/vendor/react-native/emitter/EmitterSubscription.js

@@ -0,0 +1,59 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @providesModule EmitterSubscription
+ * @flow
+ */
+'use strict';
+
+import EventSubscription from './EventSubscription';
+
+import type EventEmitter from './EventEmitter';
+import type EventSubscriptionVendor from './EventSubscriptionVendor';
+
+/**
+ * EmitterSubscription represents a subscription with listener and context data.
+ */
+class EmitterSubscription extends EventSubscription {
+
+  emitter: EventEmitter;
+  listener: Function;
+  context: ?Object;
+
+  /**
+   * @param {EventEmitter} emitter - The event emitter that registered this
+   *   subscription
+   * @param {EventSubscriptionVendor} subscriber - The subscriber that controls
+   *   this subscription
+   * @param {function} listener - Function to invoke when the specified event is
+   *   emitted
+   * @param {*} context - Optional context object to use when invoking the
+   *   listener
+   */
+  constructor(
+    emitter: EventEmitter,
+    subscriber: EventSubscriptionVendor,
+    listener: Function,
+    context: ?Object
+  ) {
+    super(subscriber);
+    this.emitter = emitter;
+    this.listener = listener;
+    this.context = context;
+  }
+
+  /**
+   * Removes this subscription from the emitter that registered it.
+   * Note: we're overriding the `remove()` method of EventSubscription here
+   * but deliberately not calling `super.remove()` as the responsibility
+   * for removing the subscription lies with the EventEmitter.
+   */
+  remove() {
+    this.emitter.removeSubscription(this);
+  }
+}
+
+export default EmitterSubscription;