thi-ng/umbrella

import type { MaybeAsyncIterable } from "@thi.ng/api";

export function zip<A>(a: MaybeAsyncIterable<A>): AsyncIterableIterator<[A]>;
export function zip<A, B>(
    a: MaybeAsyncIterable<A>,
    b: MaybeAsyncIterable<B>
): AsyncIterableIterator<[A, B]>;
export function zip<A, B, C>(
    a: MaybeAsyncIterable<A>,
    b: MaybeAsyncIterable<B>,
    c: MaybeAsyncIterable<C>
): AsyncIterableIterator<[A, B, C]>;
export function zip<A, B, C, D>(
    a: MaybeAsyncIterable<A>,
    b: MaybeAsyncIterable<B>,
    c: MaybeAsyncIterable<C>,
    d: MaybeAsyncIterable<D>
): AsyncIterableIterator<[A, B, C, D]>;
export function zip<A, B, C, D, E>(
    a: MaybeAsyncIterable<A>,
    b: MaybeAsyncIterable<B>,
    c: MaybeAsyncIterable<C>,
    d: MaybeAsyncIterable<D>,
    e: MaybeAsyncIterable<E>
): AsyncIterableIterator<[A, B, C, D, E]>;
export function zip<A, B, C, D, E, F>(
    a: MaybeAsyncIterable<A>,
    b: MaybeAsyncIterable<B>,
    c: MaybeAsyncIterable<C>,
    d: MaybeAsyncIterable<D>,
    e: MaybeAsyncIterable<E>,
    f: MaybeAsyncIterable<F>
): AsyncIterableIterator<[A, B, C, D, E, F]>;
export function zip<A, B, C, D, E, F, G>(
    a: MaybeAsyncIterable<A>,
    b: MaybeAsyncIterable<B>,
    c: MaybeAsyncIterable<C>,
    d: MaybeAsyncIterable<D>,
    e: MaybeAsyncIterable<E>,
    f: MaybeAsyncIterable<F>,
    g: MaybeAsyncIterable<G>
): AsyncIterableIterator<[A, B, C, D, E, F, G]>;
export function zip<A, B, C, D, E, F, G, H>(
    a: MaybeAsyncIterable<A>,
    b: MaybeAsyncIterable<B>,
    c: MaybeAsyncIterable<C>,
    d: MaybeAsyncIterable<D>,
    e: MaybeAsyncIterable<E>,
    f: MaybeAsyncIterable<F>,
    g: MaybeAsyncIterable<G>,
    h: MaybeAsyncIterable<H>
): AsyncIterableIterator<[A, B, C, D, E, F, G, H]>;
export async function* zip(
    ...src: MaybeAsyncIterable<any>[]
): AsyncIterableIterator<any[]> {
    const iters: (Iterator<any> | AsyncIterator<any>)[] = src.map(
        (s: any) => s[Symbol.iterator]?.() || s[Symbol.asyncIterator]?.()
    );
    while (true) {
        const tuple = [];
        for (let i of iters) {
            let v = await i.next();
            if (v.done) return;
            tuple.push(v.value);
        }
        yield tuple;
    }
}