/**
 * Options to configure a cron expression
 *
 * All fields are strings so you can use complex expressions. Absence of
 * a field implies '*' or '?', whichever one is appropriate.
 *
 * @see https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-cron-expressions.html
 */
export interface CronOptions {
    /**
       * The minute to run this rule at
       *
       * @default - Every minute
       */
    readonly minute?: string;
    /**
       * The hour to run this rule at
       *
       * @default - Every hour
       */
    readonly hour?: string;
    /**
       * The day of the month to run this rule at
       *
       * @default - Every day of the month
       */
    readonly day?: string;
    /**
       * The month to run this rule at
       *
       * @default - Every month
       */
    readonly month?: string;
    /**
       * The year to run this rule at
       *
       * @default - Every year
       */
    readonly year?: string;
    /**
       * The day of the week to run this rule at
       *
       * @default - Any day of the week
       */
    readonly weekDay?: string;
}
export declare class Cron {
    private readonly minute;
    private readonly hour;
    private readonly day;
    private readonly month;
    private readonly weekDay;
    private readonly year;
    /**
       * Create a cron expression
       */
    constructor(options: CronOptions);
    /**
       * Return the cron expression
       */
    toString(): string;
    private validate;
}