react-native/Libraries/EventEmitter/EventSubscriptionVendor.js

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/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
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*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
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*
* @providesModule EventSubscriptionVendor
* @flow
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*/
'use strict';
const invariant = require('fbjs/lib/invariant');
import type EventSubscription from 'EventSubscription';
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/**
* EventSubscriptionVendor stores a set of EventSubscriptions that are
* subscribed to a particular event type.
*/
class EventSubscriptionVendor {
_subscriptionsForType: Object;
_currentSubscription: ?EventSubscription;
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constructor() {
this._subscriptionsForType = {};
this._currentSubscription = null;
}
/**
* Adds a subscription keyed by an event type.
*
* @param {string} eventType
* @param {EventSubscription} subscription
*/
addSubscription(
eventType: string, subscription: EventSubscription): EventSubscription {
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invariant(
subscription.subscriber === this,
'The subscriber of the subscription is incorrectly set.');
if (!this._subscriptionsForType[eventType]) {
this._subscriptionsForType[eventType] = [];
}
const key = this._subscriptionsForType[eventType].length;
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this._subscriptionsForType[eventType].push(subscription);
subscription.eventType = eventType;
subscription.key = key;
return subscription;
}
/**
* Removes a bulk set of the subscriptions.
*
* @param {?string} eventType - Optional name of the event type whose
* registered supscriptions to remove, if null remove all subscriptions.
*/
removeAllSubscriptions(eventType: ?string) {
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if (eventType === undefined) {
this._subscriptionsForType = {};
} else {
delete this._subscriptionsForType[eventType];
}
}
/**
* Removes a specific subscription. Instead of calling this function, call
* `subscription.remove()` directly.
*
* @param {object} subscription
*/
removeSubscription(subscription: Object) {
const eventType = subscription.eventType;
const key = subscription.key;
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const subscriptionsForType = this._subscriptionsForType[eventType];
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if (subscriptionsForType) {
delete subscriptionsForType[key];
}
}
/**
* Returns the array of subscriptions that are currently registered for the
* given event type.
*
* Note: This array can be potentially sparse as subscriptions are deleted
* from it when they are removed.
*
* TODO: This returns a nullable array. wat?
*
* @param {string} eventType
* @returns {?array}
*/
getSubscriptionsForType(eventType: string): ?[EventSubscription] {
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return this._subscriptionsForType[eventType];
}
}
module.exports = EventSubscriptionVendor;