import { Base } from './abstract-base';
import { Stream } from './stream';
import { ClusterConfig, ClusterItems, ClusterStreamObservableProducer, InstancesMapToValuesMap } from '../models';
/**
 * A Cluster is just a wrapper, a group, of two or more ActiveJS fundamental constructs, `Units`, `Systems`, `Actions`, or even `Clusters`.
 *
 * It creates a master `Observable` of the combined value of its members by merging all the provided Observable constructs.
 * Whenever any of these wrapped constructs emits a value, `Cluster` emits a new combined-value.
 *
 * See {@link https://docs.activejs.dev/fundamentals/cluster} for more details.
 *
 * @category 4. Utility
 */
export declare class Cluster<T extends ClusterItems = ClusterItems, K extends keyof T = keyof T, V = InstancesMapToValuesMap<T>> extends Base<V> {
    /**
     * Configured options. \
     * Combination of global-options {@link GlobalUnitConfig} and the options passed on instantiation.
     */
    readonly config: Readonly<ClusterConfig>;
    /**
     * @internal please do not use.
     */
    private itemsKeys;
    /**
     * The items part of this cluster, stored as key-value pairs.
     */
    readonly items: Readonly<T>;
    /**
     * @internal please do not use.
     */
    private _itemsCount;
    /**
     * The count of items part of this cluster.
     */
    get itemsCount(): number;
    /**
     * Combined value of the items part of this Cluster.
     *
     * @category Access Value
     */
    value(): V;
    constructor(items: T, config?: ClusterConfig);
    /**
     * A helper method that creates a stream by subscribing to the Observable returned by the param `observableProducer` callback.
     *
     * Ideally the callback function creates an Observable by applying `Observable.pipe`.
     *
     * Just know that you should catch the error in a sub-pipe (ie: do not let it propagate to the main-pipe), otherwise
     * as usual the stream will stop working, and will not react on any further emissions.
     *
     * @param observableProducer A callback function that should return an Observable.
     *
     * @category Common
     */
    createStream<R>(observableProducer: ClusterStreamObservableProducer<this, R>): Stream;
    /**
     * Select a child by providing its key.
     *
     * @param key The key of the child.
     *
     * @category Custom Cluster
     */
    select<k extends K>(key: k): T[k];
    /**
     * Performs the specified action for each child of the Cluster {@link items}. \
     * It's a drop-in replacement for the `forEach` method.
     *
     * @param callbackFn A function that accepts up to three arguments.
     * forEvery calls the callbackFn function one time for each element in the list.
     * @param thisArg An object to which this keyword can refer in the callbackFn function.
     * If thisArg is omitted, undefined is used as this value.
     *
     * @category Custom Cluster
     */
    forEvery(callbackFn: (item: T[K], key: K, index: number, entries: [K, T[K]][]) => void, thisArg?: any): void;
    /** Iterator */
    [Symbol.iterator](): Iterator<[K, T[K]]>;
    /**
     * @internal please do not use.
     */
    private extractItems;
    /**
     * @internal please do not use.
     */
    private startListeningAndEmitting;
    /**
     * @internal please do not use.
     */
    protected emit(value?: V): void;
    /**
     * @internal please do not use.
     */
    private combinedEmittedValues;
}