100 lines
2.5 KiB
TypeScript
100 lines
2.5 KiB
TypeScript
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/**
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* Persistent storage, in particular `localStorage`.
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*/
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export class Storage {
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private readonly key: string;
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private _cache: { [key: string]: string } | null = null;
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/**
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* Constructs a new persistent storage item under the given key.
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*
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* @param key the unique identifier to store the data under
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*/
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constructor(key: string) {
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this.key = key;
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}
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/**
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* Reads the object stored in local storage.
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*
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* @return the object stored in local storage, or an empty object if there is nothing in the local storage
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* @private
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*/
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private read(): { [key: string]: string } {
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if (this._cache === null)
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this._cache = JSON.parse(localStorage.getItem(this.key) ?? "{}");
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return this._cache!;
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}
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/**
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* Writes the given object to local storage.
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*
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* @param item the object to write to local storage
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* @private
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*/
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private write(item: { [key: string]: string }): void {
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this._cache = item;
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localStorage.setItem(this.key, JSON.stringify(item));
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}
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/**
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* Removes the data from storage.
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*/
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clear(): void {
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this._cache = null;
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localStorage.removeItem(this.key);
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}
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/**
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* Retrieves a boolean from storage.
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*
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* @param name the name of the boolean to retrieve
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* @param def the value to return if no boolean is stored with the given name
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* @protected
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*/
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getBoolean(name: string, def: boolean = false): boolean {
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return (this.read()[name] ?? `${def}`) === "true";
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}
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/**
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* Stores a boolean.
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*
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* @param name the name of the boolean to store
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* @param value the boolean to store under the given name
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* @protected
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*/
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setBoolean(name: string, value: boolean): void {
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const item = this.read();
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item[name] = "" + value;
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this.write(item);
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}
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/**
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* Retrieves a number from storage.
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*
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* @param name the name of the number to retrieve
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* @param def the value to return if no number is stored with the given name
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* @protected
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*/
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getNumber(name: string, def: number = 0): number {
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return +(this.read()[name] ?? def);
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}
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/**
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* Stores a number.
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*
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* @param name the name of the number to store
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* @param value the number to store under the given name
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* @protected
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*/
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setNumber(name: string, value: number): void {
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const item = this.read();
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item[name] = "" + value;
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this.write(item);
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}
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}
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