import { Stream } from 'xstream';
export declare type Target = 'local' | 'session';
export declare type StorageRequest = StorageSaveRequest | StorageRemoveRequest | StorageClearRequest;
export interface StorageSaveRequest {
    target?: Target;
    action?: 'setItem';
    key: string;
    value: any;
}
export interface StorageRemoveRequest {
    target?: Target;
    action: 'removeItem';
    key: string;
}
export interface StorageClearRequest {
    action: 'clear';
    target?: Target;
}
export interface ResponseCollection {
    local: StorageSource;
    session: StorageSource;
}
export interface StorageSource {
    key(n: number): Stream<string>;
    getItem<T>(key: string): Stream<T>;
}
/**
 * Storage Driver.
 *
 * This is a localStorage and sessionStorage Driver for Cycle.js apps. The
 * driver is also a function, and it takes a stream of requests as input, and
 * returns a **`responseCollection`** with functions that allow reading from the
 * storage objects. The functions on the **`responseCollection`** return streams
 * of the storage data that was requested.
 *
 * **Requests**. The stream of requests should emit objects. These should be
 * instructions to write to the desired Storage object. Here are the `request`
 * object properties:
 *
 * - `target` *(String)*: type of storage, can be `local` or `session`, defaults
 * to `local`.
 * - `action` *(String)*: type of action, can be `setItem`, `removeItem` or
 * `clear`, defaults to `setItem`.
 * - `key` *(String)*: storage key.
 * - `value` *(String)*: storage value.
 *
 * **responseCollection**. The **`responseCollection`** is an Object that
 * exposes functions to read from local- and sessionStorage.
 *
 * ```js
 * // Returns key of nth localStorage value.
 * responseCollection.local.getKey(n)
 * // Returns localStorage value of `key`.
 * responseCollection.local.getItem(key)
 * ```
 *
 * @param request$ - a stream of write request objects.
 * @return {Object} the response collection containing functions
 * for reading from storage.
 * @function storageDriver
 */
declare function storageDriver(request$: Stream<StorageRequest>): ResponseCollection;
export default storageDriver;