import { IndexedSelector } from "../types/IndexedSelector";
import { MapFactory } from "../types/MapFactory";
/**
 * Groups elements of a sequence by key, returning a map of iterables per key.
 *
 * @typeParam T - Element type produced by the source iterable.
 * @typeParam TKey - Key type returned by `keySelector`.
 * @typeParam TValue - Value type stored in each lookup entry when `valueSelector` is supplied.
 * @param src - Source iterable to partition.
 * @param keySelector - Projection producing the lookup key for each element.
 * @param valueSelector - Optional projection producing the value to store per key; defaults to the element itself.
 * @param mapFactory - Optional factory controlling the concrete map implementation that backs the lookup.
 * @returns A map in which each key maps to an iterable of the grouped values.
 * @example
 * ```ts
 * const lookup = _toLookup(
 *   ["a", "aa", "bbb"],
 *   (value) => value.length
 * );
 * console.log([...lookup.entries()].map(([k, v]) => [k, [...v]]));
 * // [[1, ["a"]], [2, ["aa"]], [3, ["bbb"]]]
 * ```
 */
export declare function _toLookup<T, TKey>(src: Iterable<T>, keySelector: IndexedSelector<T, TKey>, mapFactory?: MapFactory<TKey>): Map<TKey, Iterable<T>>;
export declare function _toLookup<T, TKey, TValue>(src: Iterable<T>, keySelector: IndexedSelector<T, TKey>, valueSelector: IndexedSelector<T, TValue>, mapFactory?: MapFactory<TKey>): Map<TKey, Iterable<TValue>>;
/**
 * Curried version of {@link _toLookup}.
 */
export declare function toLookup<T, TKey>(keySelector: IndexedSelector<T, TKey>, mapFactory?: MapFactory<TKey>): (src: Iterable<T>) => Map<TKey, Iterable<T>>;
export declare function toLookup<T, TKey, TValue>(keySelector: IndexedSelector<T, TKey>, valueSelector: IndexedSelector<T, TValue>, mapFactory?: MapFactory<TKey>): (src: Iterable<T>) => Map<TKey, Iterable<TValue>>;