import { IndexedSelector } from "../types/IndexedSelector";
/**
 * Groups adjacent elements that share an equal key and projects each group into a result.
 *
 * @typeParam TSource - Element type produced by the source iterable.
 * @typeParam TKey - Key type generated by the key selector.
 * @typeParam TElement - Element type produced by the element selector for each group.
 * @typeParam TResult - Result type emitted by the group projection.
 * @param src - Source iterable enumerated sequentially for grouping.
 * @param keySelector - Selector producing a key for each source element.
 * @param elementSelector - Selector producing the element stored for each group member.
 * @param resultSelector - Projection invoked with the key and grouped elements.
 * @param equalityComparer - Optional key comparer; defaults to strict equality when omitted.
 * @returns A deferred iterable emitting one projected result for each run of equal keys.
 *
 * @example
 * ```ts
 * const result = [..._groupAdjacent(
 *   [1, 1, 2, 3, 3],
 *   (value) => value,
 *   (value) => value * 2,
 *   (key, items) => ({ key, doubled: [...items] })
 * )];
 * console.log(result);
 * // [
 * //   { key: 1, doubled: [2, 2] },
 * //   { key: 2, doubled: [4] },
 * //   { key: 3, doubled: [6, 6] }
 * // ]
 * ```
 *
 * or using the curried version:
 * ```ts
 * const result = pipeInto(
 *   ["a", "a", "b"],
 *   groupAdjacent(
 *     (value) => value,
 *     (value) => value.toUpperCase(),
 *     (key, items) => ({ key, items: [...items] })
 *   )
 * );
 * console.log([...result]);
 * // [
 * //   { key: "a", items: ["A", "A"] },
 * //   { key: "b", items: ["B"] }
 * // ]
 * ```
 */
export declare function _groupAdjacent<TSource, TKey, TElement, TResult>(src: Iterable<TSource>, keySelector: IndexedSelector<TSource, TKey>, elementSelector: IndexedSelector<TSource, TElement>, resultSelector: (key: TKey, items: Iterable<TElement>) => TResult, equalityComparer?: (a: TKey | undefined, b: TKey | undefined) => boolean): Iterable<TResult>;
/**
 * Curried version of {@link _groupAdjacent}.
 */
export declare const groupAdjacent: <TSource, TKey, TElement, TResult>(keySelector: IndexedSelector<TSource, TKey>, elementSelector: IndexedSelector<TSource, TElement>, resultSelector: (key: TKey, items: Iterable<TElement>) => TResult, equalityComparer?: ((a: TKey | undefined, b: TKey | undefined) => boolean) | undefined) => (src: Iterable<TSource>) => Iterable<TResult>;