jiti-meet/react/features/mobile/polyfills/Storage.js

193 lines
6.6 KiB
JavaScript
Raw Normal View History

import AsyncStorage from '@react-native-community/async-storage';
/**
* A Web Sorage API implementation used for polyfilling
* {@code window.localStorage} and/or {@code window.sessionStorage}.
* <p>
* The Web Storage API is synchronous whereas React Native's builtin generic
* storage API {@code AsyncStorage} is asynchronous so the implementation with
* persistence is optimistic: it will first store the value locally in memory so
* that results can be served synchronously and then persist the value
* asynchronously. If an asynchronous operation produces an error, it's ignored.
*/
export default class Storage {
/**
* Initializes a new {@code Storage} instance. Loads all previously
* persisted data items from React Native's {@code AsyncStorage} if
* necessary.
*
* @param {string|undefined} keyPrefix - The prefix of the
* {@code AsyncStorage} keys to be persisted by this storage.
*/
constructor(keyPrefix) {
/**
* The prefix of the {@code AsyncStorage} keys persisted by this
* storage. If {@code undefined}, then the data items stored in this
* storage will not be persisted.
*
* @private
* @type {string}
*/
this._keyPrefix = keyPrefix;
// Perform optional asynchronous initialization.
const initializing = this._initializeAsync();
if (initializing) {
// Indicate that asynchronous initialization is under way.
this._initializing = initializing;
// When the asynchronous initialization completes, indicate its
// completion.
initializing.finally(() => {
if (this._initializing === initializing) {
this._initializing = undefined;
}
});
}
}
/**
* Removes all keys from this storage.
*
* @returns {void}
*/
clear() {
for (const key of Object.keys(this)) {
this.removeItem(key);
}
}
/**
* Returns the value associated with a specific key in this storage.
*
* @param {string} key - The name of the key to retrieve the value of.
* @returns {string|null} The value associated with {@code key} or
* {@code null}.
*/
getItem(key) {
return this.hasOwnProperty(key) ? this[key] : null;
}
/**
* Returns the value associated with a specific key in this {@code Storage}
* in an async manner. The method is required for the cases where we need
* the stored data but we're not sure yet whether this {@code Storage} is
* already initialized (e.g. On app start).
*
* @param {string} key - The name of the key to retrieve the value of.
* @returns {Promise}
*/
_getItemAsync(key) {
return (
(this._initializing || Promise.resolve())
.catch(() => { /* _getItemAsync should always resolve! */ })
.then(() => this.getItem(key)));
}
/**
* Performs asynchronous initialization of this {@code Storage} instance
* such as loading all keys from {@link AsyncStorage}.
*
* @private
* @returns {Promise}
*/
_initializeAsync() {
if (typeof this._keyPrefix !== 'undefined') {
// Load all previously persisted data items from React Native's
// AsyncStorage.
return new Promise(resolve => {
AsyncStorage.getAllKeys().then((...getAllKeysCallbackArgs) => {
// XXX The keys argument of getAllKeys' callback may or may
// not be preceded by an error argument.
const keys
= getAllKeysCallbackArgs[
getAllKeysCallbackArgs.length - 1
].filter(key => key.startsWith(this._keyPrefix));
AsyncStorage.multiGet(keys)
.then((...multiGetCallbackArgs) => {
// XXX The result argument of multiGet may or may not be
// preceded by an errors argument.
const result
= multiGetCallbackArgs[
multiGetCallbackArgs.length - 1
];
const keyPrefixLength
= this._keyPrefix && this._keyPrefix.length;
// eslint-disable-next-line prefer-const
for (let [ key, value ] of result) {
key = key.substring(keyPrefixLength);
// XXX The loading of the previously persisted data
// items from AsyncStorage is asynchronous which
// means that it is technically possible to invoke
// setItem with a key before the key is loaded from
// AsyncStorage.
if (!this.hasOwnProperty(key)) {
this[key] = value;
}
}
resolve();
});
});
});
}
return undefined;
2017-12-13 10:35:42 +00:00
}
/**
* Returns the name of the nth key in this storage.
*
* @param {number} n - The zero-based integer index of the key to get the
* name of.
* @returns {string} The name of the nth key in this storage.
*/
key(n) {
const keys = Object.keys(this);
return n < keys.length ? keys[n] : null;
}
/**
* Returns an integer representing the number of data items stored in this
* storage.
*
* @returns {number}
*/
get length() {
return Object.keys(this).length;
}
/**
* Removes a specific key from this storage.
*
* @param {string} key - The name of the key to remove.
* @returns {void}
*/
removeItem(key) {
delete this[key];
typeof this._keyPrefix === 'undefined'
|| AsyncStorage.removeItem(`${String(this._keyPrefix)}${key}`);
}
/**
* Adds a specific key to this storage and associates it with a specific
* value. If the key exists already, updates its value.
*
* @param {string} key - The name of the key to add/update.
* @param {string} value - The value to associate with {@code key}.
* @returns {void}
*/
setItem(key, value) {
value = String(value); // eslint-disable-line no-param-reassign
this[key] = value;
typeof this._keyPrefix === 'undefined'
|| AsyncStorage.setItem(`${String(this._keyPrefix)}${key}`, value);
}
}