interface StateInterface

interface StateInterface {
    
    /**
     * Returns the stored value for a given key.
     *
     * @param string $key
     *   The key of the data to retrieve.
     * @param mixed $default
     *   The default value to use if the key is not found.
     *
     * @return mixed
     *   The stored value, or NULL if no value exists.
     */
    public function get($key, $default = NULL);
    
    /**
     * Returns the stored key/value pairs for a given set of keys.
     *
     * @param array $keys
     *   A list of keys to retrieve.
     *
     * @return array
     *   An associative array of items successfully returned, indexed by key.
     */
    public function getMultiple(array $keys);
    
    /**
     * Saves a value for a given key.
     *
     * @param string $key
     *   The key of the data to store.
     * @param mixed $value
     *   The data to store.
     */
    public function set($key, $value);
    
    /**
     * Saves key/value pairs.
     *
     * @param array $data
     *   An associative array of key/value pairs.
     */
    public function setMultiple(array $data);
    
    /**
     * Deletes an item.
     *
     * @param string $key
     *   The item name to delete.
     */
    public function delete($key);
    
    /**
     * Deletes multiple items.
     *
     * @param array $keys
     *   A list of item names to delete.
     */
    public function deleteMultiple(array $keys);
    
    /**
     * Resets the static cache.
     *
     * This is mainly used in testing environments.
     */
    public function resetCache();

}