import { IndexedSelector } from "../types/IndexedSelector";
import { MapFactory } from "../types/MapFactory";
/**
 * Performs a group join pairing each outer element with the group of matching inner elements.
 *
 * @typeParam T - Element type produced by the outer source iterable.
 * @typeParam TInner - Element type produced by the inner source iterable.
 * @typeParam TKey - Key type generated by the key selector functions.
 * @typeParam TOut - Result type emitted by the `selector`.
 * @param src - Outer source iterable enumerated sequentially.
 * @param innerSeq - Inner source iterable used to build a lookup for matching keys.
 * @param outerKeySelector - Selector producing a key for each outer element.
 * @param innerKeySelector - Selector producing a key for each inner element.
 * @param selector - Projection receiving the current outer element and the iterable of matching inner elements.
 * @param mapFactory - Optional factory used to create the internal map for lookups.
 * @returns A deferred iterable yielding the result of `selector` for every element in the outer sequence.
 *
 * @example
 * ```ts
 * const result = [..._groupJoin(
 *   [
 *     { id: 1, name: "Alice" },
 *     { id: 2, name: "Bob" }
 *   ],
 *   [
 *     { userId: 1, order: "A" },
 *     { userId: 1, order: "B" },
 *     { userId: 3, order: "C" }
 *   ],
 *   (user) => user.id,
 *   (order) => order.userId,
 *   (user, orders) => ({
 *     name: user.name,
 *     orders: [...orders].map((order) => order.order)
 *   })
 * )];
 * console.log(result);
 * // [
 * //   { name: "Alice", orders: ["A", "B"] },
 * //   { name: "Bob", orders: [] }
 * // ]
 * ```
 *
 * or using the curried version:
 * ```ts
 * const result = pipeInto(
 *   [
 *     { id: 1, name: "Taylor" }
 *   ],
 *   groupJoin(
 *     [
 *       { userId: 1, order: "Order-1" },
 *       { userId: 2, order: "Order-2" }
 *     ],
 *     (user) => user.id,
 *     (order) => order.userId,
 *     (user, orders) => ({
 *       name: user.name,
 *       orders: [...orders].map((order) => order.order)
 *     })
 *   )
 * );
 * console.log([...result]);
 * // [
 * //   { name: "Taylor", orders: ["Order-1"] }
 * // ]
 * ```
 */
export declare function _groupJoin<T, TInner, TKey, TOut>(src: Iterable<T>, innerSeq: Iterable<TInner>, outerKeySelector: IndexedSelector<T, TKey>, innerKeySelector: IndexedSelector<TInner, TKey>, selector: (o: T, v: Iterable<TInner>) => TOut, mapFactory?: MapFactory<TKey>): Iterable<TOut>;
/**
 * Curried version of {@link _groupJoin}.
 */
export declare const groupJoin: <T, TInner, TKey, TOut>(innerSeq: Iterable<TInner>, outerKeySelector: IndexedSelector<T, TKey>, innerKeySelector: IndexedSelector<TInner, TKey>, selector: (o: T, v: Iterable<TInner>) => TOut, mapFactory?: MapFactory<TKey> | undefined) => (src: Iterable<T>) => Iterable<TOut>;