import { Iterator, Source } from "./lazy";
import type { AnyObject, Options } from "./types";
/**
 * The `Aggregator` class provides functionality to process data collections
 * through an aggregation pipeline. It supports streaming and executing
 * aggregation operations with customizable options.
 */
export declare class Aggregator {
    #private;
    /**
     * Creates an instance of the Aggregator class.
     *
     * @param pipeline - An array of objects representing the aggregation pipeline stages.
     * @param options - Optional configuration settings for the aggregator.
     */
    constructor(pipeline: AnyObject[], options: Partial<Options>);
    /**
     * Processes a collection through an aggregation pipeline and returns an iterator
     * for the transformed results.
     *
     * @param collection - The input collection to process. This can be any source
     *   that implements the `Source` interface.
     * @param options - Optional configuration for processing. If not provided, the
     *   default options of the aggregator instance will be used.
     * @returns An iterator that yields the results of the aggregation pipeline.
     *
     * @throws Will throw an error if:
     * - A pipeline stage contains more than one operator.
     * - The `$documents` operator is not the first stage in the pipeline.
     * - An unregistered pipeline operator is encountered.
     */
    stream(collection: Source, options?: Options): Iterator;
    /**
     * Executes the aggregation pipeline on the provided collection and returns the resulting array.
     *
     * @template T - The type of the objects in the resulting array.
     * @param collection - The input data source to run the aggregation on.
     * @param options - Optional settings to customize the aggregation behavior.
     * @returns An array of objects of type `T` resulting from the aggregation.
     */
    run<T extends AnyObject>(collection: Source, options?: Options): T[];
}