Files
react-native/Libraries/EventEmitter/NativeEventEmitter.js
T
Rubén Norte fa406ac2aa Implement typed event emitters
Summary:
Adds types to Event Emitters and migrates the most relevant modules using them in `react-native`.

The most relevant file of this diff is `react-native/Libraries/vendor/emitter/__flowtests__/EventEmitter-flowtest.js` with the Flow tests showing and testing the behavior of the new types

Changelog: [Internal] Add types for Event Emitters and subclasses

Reviewed By: motiz88

Differential Revision: D25587936

fbshipit-source-id: feeb09f9ad15d383cdd82deaaaba0d12b94e868b
2021-01-07 03:19:04 -08:00

85 lines
2.6 KiB
JavaScript

/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @format
* @flow
*/
'use strict';
import Platform from '../Utilities/Platform';
import EventEmitter from '../vendor/emitter/EventEmitter';
import type EmitterSubscription from '../vendor/emitter/_EmitterSubscription';
import RCTDeviceEventEmitter from './RCTDeviceEventEmitter';
import invariant from 'invariant';
type NativeModule = {
+addListener: (eventType: string) => void,
+removeListeners: (count: number) => void,
...
};
type NativeEventEmitterOptions = $ReadOnly<{|
__SECRET_DISABLE_CALLS_INTO_MODULE_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: boolean,
|}>;
const DEFAULT_NATIVE_EVENT_EMITTER_OPTIONS = {
__SECRET_DISABLE_CALLS_INTO_MODULE_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: false,
};
/**
* Abstract base class for implementing event-emitting modules. This implements
* a subset of the standard EventEmitter node module API.
*/
export default class NativeEventEmitter<
EventDefinitions: {...},
> extends EventEmitter<EventDefinitions> {
_nativeModule: ?NativeModule;
_disableCallsIntoModule: boolean;
constructor(
nativeModule: ?NativeModule,
options: NativeEventEmitterOptions = DEFAULT_NATIVE_EVENT_EMITTER_OPTIONS,
) {
super(RCTDeviceEventEmitter.sharedSubscriber);
this._disableCallsIntoModule =
options.__SECRET_DISABLE_CALLS_INTO_MODULE_DO_NOT_USE_OR_YOU_WILL_BE_FIRED;
if (Platform.OS === 'ios') {
invariant(nativeModule, 'Native module cannot be null.');
this._nativeModule = nativeModule;
}
}
addListener<K: $Keys<EventDefinitions>>(
eventType: K,
listener: (...$ElementType<EventDefinitions, K>) => mixed,
context: $FlowFixMe,
): EmitterSubscription<EventDefinitions, K> {
if (this._nativeModule != null && !this._disableCallsIntoModule) {
this._nativeModule.addListener(eventType);
}
return super.addListener(eventType, listener, context);
}
removeAllListeners<K: $Keys<EventDefinitions>>(eventType: ?K): void {
invariant(eventType, 'eventType argument is required.');
const count = this.listenerCount(eventType);
if (this._nativeModule != null && !this._disableCallsIntoModule) {
this._nativeModule.removeListeners(count);
}
super.removeAllListeners(eventType);
}
removeSubscription<K: $Keys<EventDefinitions>>(
subscription: EmitterSubscription<EventDefinitions, K>,
): void {
if (this._nativeModule != null && !this._disableCallsIntoModule) {
this._nativeModule.removeListeners(1);
}
super.removeSubscription(subscription);
}
}