import { BaseStorageService } from './base-storage.service';
/**
 * An implementation of `StorageService` interface that uses an underlying (web) `Storage` object, such as `localStorage` and
 * `sessionStorage`, as backing data store. This class basically wraps the `Storage` object so it can be accessed through the
 * `StorageService` interface.
 */
export declare class WebStorageService extends BaseStorageService<any> {
    private readonly storage;
    /**
     * Creates a new `WebStorageService` instance that uses the specified (web) storage object as underlying backing storage.
     *
     * @param storage Storage object which is to be wrapped in a class that implements the `StorageService` interface.
     */
    constructor(storage: Storage);
    /**
     * Checks whether an entry with the specified key exists in the storage.
     *
     * @param   key Identifier of the entry for which its presence in the storage is to be checked.
     * @returns     `true` if an entry with the specified key exists in the storage, `false` if not.
     */
    has(key: string): boolean;
    /**
     * Removes the entry that is identified by the specified key. Attempting to remove an entry for an unknown key will have no effect.
     * Attempting to retrieve an entry via the `get` method after it has been removed will result in `undefined`.
     *
     * @param key Identifier of the entry which is to be removed.
     */
    remove(key: string): void;
    /**
     * Clears the storage by removing all entries. Subsequent `get(x)` calls for a key *x* will return `undefined`, until a new value is set
     * for key *x*.
     */
    clear(): void;
    /**
     * Performs the actual retrieval of a value from storage.
     *
     * @param   key Identifier of the entry whose value is to be retrieved.
     * @returns     The value that is stored for the specified entry or `undefined` if no entry exists for the specified key.
     */
    protected getItem(key: string): string | undefined;
    /**
     * Stores the provided value using specified key in the storage.
     *
     * @param key   Identifier of the entry for which the value is to be stored.
     * @param value The value that is to be stored.
     */
    protected setItem(key: string, value: string): void;
}
/**
 * Checks whether the specified (web) storage is available and functional. This might not be the case for older browsers. However even
 * certain browsers that do support the web storage API can, under some circumstances, have non functional storage objects. For example,
 * Safari is known to have `localStorage` and `sessionStorage` throw exceptions in private mode.
 *
 * @param   storage Storage object which is to be tested for availability.
 * @returns         `true` if the specified storage can be used, `false` if not.
 */
export declare function isStorageAvailable(storage: Storage): boolean;
/**
 * Checks whether session storage is available and functional. This might not be the case for older browsers. However even certain browsers
 * that do support the web storage API can, under some circumstances, have non functional storage objects. For example, Safari is known to
 * have `sessionStorage` throw exceptions in private mode.
 *
 * @returns `true` if session storage can be used, `false` if not.
 */
export declare function isSessionStorageAvailable(): boolean;
/**
 * Checks whether local storage is available and functional. This might not be the case for older browsers. However even certain browsers
 * that do support the web storage API can, under some circumstances, have non functional storage objects. For example, Safari is known to
 * have `localStorage` throw exceptions in private mode.
 *
 * @returns `true` if local storage can be used, `false` if not.
 */
export declare function isLocalStorageAvailable(): boolean;