ix/src/asynciterable/operators/dowhile.ts

The Interactive Extensions for JavaScript

import { AsyncIterableX } from '../asynciterablex.js';
import { concat } from '../concat.js';
import { whileDo } from '../whiledo.js';
import { MonoTypeOperatorAsyncFunction } from '../../interfaces.js';

/**
 * Generates an async-iterable sequence by repeating a source sequence as long as the given loop postcondition holds.
 *
 * @template TSource The type of elements in the source sequence.
 * @param {((signal?: AbortSignal) => boolean | Promise<boolean>)} condition Loop condition.
 * @returns {MonoTypeOperatorAsyncFunction<TSource>} An operator that generates an async-iterable by repeating a
 * source sequence while the postcondition holds.
 */
export function doWhile<TSource>(
  condition: (signal?: AbortSignal) => boolean | Promise<boolean>
): MonoTypeOperatorAsyncFunction<TSource> {
  return function doWhileOperatorFunction(source: AsyncIterable<TSource>): AsyncIterableX<TSource> {
    return concat(source, whileDo(source, condition));
  };
}