145a5a8a8d
* Conform more code to strict null checking * Conform more code to strict null checking * Iterate * Iterate
112 lines
4.1 KiB
TypeScript
112 lines
4.1 KiB
TypeScript
/*
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Copyright 2019 - 2022 The Matrix.org Foundation C.I.C.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import SettingsHandler from "./SettingsHandler";
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/**
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* Abstract settings handler wrapping around localStorage making getValue calls cheaper
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* by caching the values and listening for localStorage updates from other tabs.
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*/
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export default abstract class AbstractLocalStorageSettingsHandler extends SettingsHandler {
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// Shared cache between all subclass instances
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private static itemCache = new Map<string, string | null>();
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private static objectCache = new Map<string, object>();
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private static storageListenerBound = false;
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private static onStorageEvent = (e: StorageEvent): void => {
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if (e.key === null) {
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AbstractLocalStorageSettingsHandler.clear();
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} else {
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AbstractLocalStorageSettingsHandler.itemCache.delete(e.key);
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AbstractLocalStorageSettingsHandler.objectCache.delete(e.key);
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}
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};
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// Expose the clear event for Lifecycle to call, the storage listener only fires for changes from other tabs
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public static clear(): void {
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AbstractLocalStorageSettingsHandler.itemCache.clear();
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AbstractLocalStorageSettingsHandler.objectCache.clear();
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}
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protected constructor() {
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super();
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if (!AbstractLocalStorageSettingsHandler.storageListenerBound) {
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AbstractLocalStorageSettingsHandler.storageListenerBound = true;
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// Listen for storage changes from other tabs to bust the cache
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window.addEventListener("storage", AbstractLocalStorageSettingsHandler.onStorageEvent);
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}
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}
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protected getItem(key: string): string | null {
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if (!AbstractLocalStorageSettingsHandler.itemCache.has(key)) {
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const value = localStorage.getItem(key);
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AbstractLocalStorageSettingsHandler.itemCache.set(key, value);
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return value;
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}
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return AbstractLocalStorageSettingsHandler.itemCache.get(key)!;
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}
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protected getBoolean(key: string): boolean | null {
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const item = this.getItem(key);
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if (item === "true") return true;
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if (item === "false") return false;
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// Fall back to the next config level
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return null;
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}
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protected getObject<T extends object>(key: string): T | null {
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if (!AbstractLocalStorageSettingsHandler.objectCache.has(key)) {
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try {
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const value = JSON.parse(localStorage.getItem(key)!);
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AbstractLocalStorageSettingsHandler.objectCache.set(key, value);
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return value;
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} catch (err) {
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console.error("Failed to parse localStorage object", err);
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return null;
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}
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}
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return AbstractLocalStorageSettingsHandler.objectCache.get(key) as T;
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}
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protected setItem(key: string, value: string): void {
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AbstractLocalStorageSettingsHandler.itemCache.set(key, value);
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localStorage.setItem(key, value);
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}
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protected setBoolean(key: string, value: boolean | null): void {
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this.setItem(key, `${value}`);
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}
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protected setObject(key: string, value: object): void {
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AbstractLocalStorageSettingsHandler.objectCache.set(key, value);
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localStorage.setItem(key, JSON.stringify(value));
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}
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// handles both items and objects
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protected removeItem(key: string): void {
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localStorage.removeItem(key);
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AbstractLocalStorageSettingsHandler.itemCache.delete(key);
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AbstractLocalStorageSettingsHandler.objectCache.delete(key);
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}
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public isSupported(): boolean {
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return localStorage !== undefined && localStorage !== null;
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}
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}
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