Function parseCronExpression

packages/agent-core/src/tools/cron/cron-expr.ts:47–87

(expr: string)

 * lists (`a,b,c`), and step (e.g. star-slash-n or `a-b/n`).
 */
export function parseCronExpression(expr: string): ParsedCronExpression {
  if (typeof expr !== 'string') {
    throw new TypeError('cron expression must be a string');
  }
  const trimmed = expr.trim();
  if (trimmed === '') {
    throw new Error('cron expression is empty');
  }
  const fields = trimmed.split(/\s+/);
  if (fields.length !== 5) {
    throw new Error(
      `cron expression must have exactly 5 fields (minute hour day-of-month month day-of-week); got ${fields.length}`,
    );
  }
  const [minField, hourField, domField, monthField, dowField] = fields as [
    string,
    string,
    string,
    string,
    string,
  ];

  const minutes = parseField(minField, MINUTE_RANGE.min, MINUTE_RANGE.max, 'minute');
  const hours = parseField(hourField, HOUR_RANGE.min, HOUR_RANGE.max, 'hour');
  const daysOfMonth = parseField(domField, DOM_RANGE.min, DOM_RANGE.max, 'day-of-month');
  const months = parseField(monthField, MONTH_RANGE.min, MONTH_RANGE.max, 'month');
  const dowRaw = parseField(dowField, DOW_RANGE.min, DOW_RANGE.max, 'day-of-week');
  const daysOfWeek = new Set<number>();
  for (const v of dowRaw) daysOfWeek.add(v === 7 ? 0 : v);

  return {
    raw: trimmed,
    minutes,
    hours,
    daysOfMonth,
    months,
    daysOfWeek,
    daysOfMonthWildcard: isWildcard(domField),
    daysOfWeekWildcard: isWildcard(dowField),
  };
}

function isWildcard(field: string): boolean {
  // `*` and `*/n` both leave the field unconstrained in the