import type { SubscriptionAction } from './subscription-actions';
export interface QueuedItem {
    action: SubscriptionAction;
    args?: {
        force?: boolean;
        [p: string]: any;
    };
}
/**
 * Queue (FIFO) of pending subscription actions. Allows for easier abstraction of managing list of pending actions.
 * In addition to standard queue implementation, provides:
 *  - merging consecutive duplicated actions
 *  - merging of uneccessary combinations: ACTION_SUBSCRIBE action before ACTION_UNSUBSCRIBE, is merged to ACTION_UNSUBSCRIBE.
 */
declare class SubscriptionQueue {
    items: QueuedItem[];
    private getLastItem;
    /**
     * Add pending action to a queue and making sure that we remove unecessary actions like:
     * - duplicates.
     * - ACTION_SUBSCRIBE action before ACTION_UNSUBSCRIBE.
     *
     * @param queuedItem - action with arguments to add to the queue.
     */
    enqueue(queuedItem: QueuedItem): void;
    /**
     * This is called at the point of subscribing or on a subscribe error.
     * We know at that point we do not need any follow up modifys
     * or subscribes.
     */
    clearModifys(): boolean;
    /**
     * Returns the action from the beginning of a queue without removing it.
     * @returns  Next action.
     */
    peekAction(): SubscriptionAction | undefined;
    /**
     * Peeks the next action
     */
    peek(): QueuedItem | undefined;
    /**
     * Looks to see if the end state after processing actions is to be unsubscribed or not
     * If the actions are indeterminate (for example, no actions) then it returns the current
     * state passed as a argument
     */
    peekIsSubscribed(isSubscribedNow: boolean): boolean;
    /**
     * Removes and returns the action from the beginning of a queue.
     * @returns  First action, if queue is not empty. Otherwise undefined.
     */
    dequeue(): QueuedItem | undefined;
    /**
     * Resets queue.
     */
    reset(): void;
    /**
     * @returns True if empty.
     */
    isEmpty(): boolean;
}
export default SubscriptionQueue;