src/range.js

import rangeArgs from './rangeArgs.js';
import ForwardRange from './ForwardRange.js';
import BackwardRange from './BackwardRange.js';

/**
 * Constructs a {@link Range} whose iterator yields values in an interval,
 * separated by a fixed constant called step. If this step is negative, the
 * range has to be given in reverse order, that is, largest value first,
 * smallest value second. Both the starting value and the step value are
 * optional. By default the starting value is <code>0</code>. The default for
 * the step value is <code>1</code>.
 *
 * @param {number} [start=0] - The starting value.
 * @param {number} stop - The stopping value.
 * @param {number} [step=1] - The step value.
 * @returns {ForwardRange|BackwardRange}
 */
const range = (start, stop, step) => {
	[start, stop, step] = rangeArgs(start, stop, step);
	return step < 0
		? new BackwardRange(start, stop, step)
		: new ForwardRange(start, stop, step);
};

export default range;