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90403154a2
Summary: …while an event is dispatched While it is guarded, a copy of the Set is created before listeners are added or removed. The event dispatch loop continues with the old Set of listeners. This PR modifies `BackAndroid` to match the proposal at the end of #5781. Closes https://github.com/facebook/react-native/pull/5783 Reviewed By: svcscm Differential Revision: D2911282 Pulled By: foghina fb-gh-sync-id: 34964ec3414af85eb9574bbcef081238fc67ffaf
80 lines
1.9 KiB
JavaScript
80 lines
1.9 KiB
JavaScript
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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* @providesModule BackAndroid
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*/
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'use strict';
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var DeviceEventManager = require('NativeModules').DeviceEventManager;
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var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
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var DEVICE_BACK_EVENT = 'hardwareBackPress';
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type BackPressEventName = $Enum<{
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backPress: string;
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}>;
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var _backPressSubscriptions = new Set();
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RCTDeviceEventEmitter.addListener(DEVICE_BACK_EVENT, function() {
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var backPressSubscriptions = new Set(_backPressSubscriptions);
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var invokeDefault = true;
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backPressSubscriptions.forEach((subscription) => {
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if (subscription()) {
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invokeDefault = false;
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}
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});
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if (invokeDefault) {
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BackAndroid.exitApp();
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}
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});
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/**
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* Detect hardware back button presses, and programmatically invoke the default back button
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* functionality to exit the app if there are no listeners or if none of the listeners return true.
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*
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* Example:
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*
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* ```js
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* BackAndroid.addEventListener('hardwareBackPress', function() {
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* if (!this.onMainScreen()) {
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* this.goBack();
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* return true;
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* }
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* return false;
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* });
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* ```
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*/
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var BackAndroid = {
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exitApp: function() {
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DeviceEventManager.invokeDefaultBackPressHandler();
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},
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addEventListener: function (
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eventName: BackPressEventName,
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handler: Function
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): {remove: () => void} {
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_backPressSubscriptions.add(handler);
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return {
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remove: () => BackAndroid.removeEventListener(eventName, handler),
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};
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},
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removeEventListener: function(
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eventName: BackPressEventName,
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handler: Function
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): void {
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_backPressSubscriptions.delete(handler);
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},
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};
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module.exports = BackAndroid;
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