thi-ng/umbrella

import type { IObjectOf } from "@thi.ng/api";
import type { MultiplexTxLike, Reducer, Transducer } from "./api.js";
import { comp } from "./comp.js";
import { __iter } from "./iterator.js";
import { multiplex } from "./multiplex.js";
import { rename } from "./rename.js";

/**
 * Transducer. Similar to (and building on) {@link multiplex}, but takes an
 * object of transducers and produces a result object for each input.
 *
 * @example
 * ```ts
 * import { multiplexObj } from "@thi.ng/transducers";
 *
 * [...multiplexObj(
 *   {
 *     initial: map(x => x.charAt(0)),
 *     upper:   map(x => x.toUpperCase()),
 *     length:  map(x => x.length)
 *   },
 *   ["Alice", "Bob", "Charlie"]
 * )]
 * // [ { length: 5, upper: 'ALICE', initial: 'A' },
 * //   { length: 3, upper: 'BOB', initial: 'B' },
 * //   { length: 7, upper: 'CHARLIE', initial: 'C' } ]
 * ```
 *
 * @param xforms - object of transducers
 * @param rfn -
 */
export function multiplexObj<A, B>(
    xforms: IObjectOf<MultiplexTxLike<A, any>>,
    rfn?: Reducer<[PropertyKey, any], B>
): Transducer<A, B>;
export function multiplexObj<A, B>(
    xforms: IObjectOf<MultiplexTxLike<A, any>>,
    src: Iterable<A>
): IterableIterator<B>;
export function multiplexObj<A, B>(
    xforms: IObjectOf<MultiplexTxLike<A, any>>,
    rfn: Reducer<[PropertyKey, any], B>,
    src: Iterable<A>
): IterableIterator<B>;
export function multiplexObj(...args: any[]): any {
    const iter = __iter(multiplexObj, args);
    if (iter) {
        return iter;
    }
    const [xforms, rfn] = args;
    const ks = Object.keys(xforms);
    return comp(
        multiplex.apply(null, <any>ks.map((k) => xforms[k])),
        rename(ks, rfn)
    );
}