import type { Observable } from './Observable.js';
import type { ObservableCallback } from './ObservableCallback.js';
/**
 * An {@link Observable} which transforms a list of input Observables into a
 * single value efficiently.
 *
 * @category State Management
 */
export declare class ObservableTransformer<V, I extends Iterable<Observable<U>> | [Observable<U>], U = unknown> implements Observable<V> {
    readonly inputs: I;
    readonly transformer: (inputs: I) => V;
    readonly decider?: ((inputs: I) => boolean) | undefined;
    private dirty;
    private cache;
    private watcher;
    /** The function callbacks called when the value is changed */
    private callbacks;
    /**
     * The current value.
     *
     * Evaluated when needed. Values are cached.
     */
    get value(): V;
    /**
     * @param inputs - The list of observables to use as inputs for this transformer.
     * @param transformer - The actual transformer function. Takes in a list of input observables, and outputs a single value.
     * @param decider - Decides whether the transformer's output value needs to be updated or not. If `undefined` (the default), then the value is always assumed to need to be updated whenever an input watcher is invoked.
     */
    constructor(inputs: I, transformer: (inputs: I) => V, decider?: ((inputs: I) => boolean) | undefined);
    destroy(): void;
    watch(callback: ObservableCallback<V>, callNow?: boolean, group?: unknown): this;
    unwatch(callback: ObservableCallback<V>): this;
    private doCallback;
}