ix/src/iterable/whiledo.ts

The Interactive Extensions for JavaScript

import { IterableX } from './iterablex.js';

class WhileIterable<TSource> extends IterableX<TSource> {
  private _condition: () => boolean;
  private _source: Iterable<TSource>;

  constructor(condition: () => boolean, source: Iterable<TSource>) {
    super();
    this._condition = condition;
    this._source = source;
  }

  *[Symbol.iterator]() {
    while (this._condition()) {
      yield* this._source;
    }
  }
}

/**
 * Repeats the given source as long as the specified conditions holds, where
 * the condition is evaluated before each repeated source is iterated.
 *
 * @template TSource
 * @param {Iterable<TSource>} source Source to repeat as long as the condition function evaluates to true.
 * @param {((signal?: AbortSignal) => boolean)} condition Condition that will be evaluated before the source sequence is iterated.
 * @returns {IterableX<TSource>} An iterable which is repeated while the condition returns true.
 */
export function whileDo<TSource>(
  source: Iterable<TSource>,
  condition: () => boolean
): IterableX<TSource> {
  return new WhileIterable<TSource>(condition, source);
}