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111 lines
3.9 KiB
111 lines
3.9 KiB
import {safeJsonParse} from 'app/common/gutil';
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import {Observable} from 'grainjs';
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/**
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* Returns true if storage is functional. In some cass (e.g. when embedded), localStorage may
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* throw errors. If so, we return false. This implementation is the approach taken by store.js.
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*/
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function testStorage(storage: Storage) {
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try {
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const testStr = '__localStorage_test';
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storage.setItem(testStr, testStr);
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const ok = (storage.getItem(testStr) === testStr);
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storage.removeItem(testStr);
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return ok;
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} catch (e) {
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return false;
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}
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}
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/**
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* Returns localStorage if functional, or sessionStorage, or an in-memory storage. The fallbacks
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* help with tests, and may help when Grist is embedded.
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*/
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export function getStorage(): Storage {
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return _storage || (_storage = createStorage());
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}
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/**
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* Similar to `getStorage`, but always returns sessionStorage (or an in-memory equivalent).
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*/
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export function getSessionStorage(): Storage {
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return _sessionStorage || (_sessionStorage = createSessionStorage());
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}
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let _storage: Storage|undefined;
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let _sessionStorage: Storage|undefined;
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function createStorage(): Storage {
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if (typeof localStorage !== 'undefined' && testStorage(localStorage)) {
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return localStorage;
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} else {
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return createSessionStorage();
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}
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}
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function createSessionStorage(): Storage {
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if (typeof sessionStorage !== 'undefined' && testStorage(sessionStorage)) {
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return sessionStorage;
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} else {
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// Fall back to a Map-based implementation of (non-persistent) sessionStorage.
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return createInMemoryStorage();
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}
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}
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function createInMemoryStorage(): Storage {
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const values = new Map<string, string>();
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return {
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setItem(key: string, val: string) { values.set(key, val); },
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getItem(key: string) { return values.get(key) ?? null; },
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removeItem(key: string) { values.delete(key); },
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clear() { values.clear(); },
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get length() { return values.size; },
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key(index: number): string|null { throw new Error('Not implemented'); },
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};
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}
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function getStorageBoolObs(store: Storage, key: string, defValue: boolean) {
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const storedNegation = defValue ? 'false' : 'true';
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const obs = Observable.create(null, store.getItem(key) === storedNegation ? !defValue : defValue);
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obs.addListener((val) => val === defValue ? store.removeItem(key) : store.setItem(key, storedNegation));
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return obs;
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}
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/**
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* Helper to create a boolean observable whose state is stored in localStorage.
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*
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* Optionally, a default value of true will make the observable start off as true. Note that the
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* same default value should be used for an observable every time it's created.
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*/
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export function localStorageBoolObs(key: string, defValue = false): Observable<boolean> {
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return getStorageBoolObs(getStorage(), key, defValue);
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}
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/**
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* Similar to `localStorageBoolObs`, but always uses sessionStorage (or an in-memory equivalent).
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*/
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export function sessionStorageBoolObs(key: string, defValue = false): Observable<boolean> {
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return getStorageBoolObs(getSessionStorage(), key, defValue);
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}
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/**
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* Helper to create a string observable whose state is stored in localStorage.
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*/
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export function localStorageObs(key: string, defaultValue?: string): Observable<string|null> {
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const store = getStorage();
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const obs = Observable.create<string|null>(null, store.getItem(key) ?? defaultValue ?? null);
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obs.addListener((val) => (val === null) ? store.removeItem(key) : store.setItem(key, val));
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return obs;
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}
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/**
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* Helper to create a JSON observable whose state is stored in localStorage.
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*/
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export function localStorageJsonObs<T>(key: string, defaultValue: T): Observable<T> {
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const store = getStorage();
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const currentValue = safeJsonParse(store.getItem(key) || '', defaultValue ?? null);
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const obs = Observable.create<T>(null, currentValue);
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obs.addListener((val) => (val === null) ? store.removeItem(key) : store.setItem(key, JSON.stringify(val ?? null)));
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return obs;
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}
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