import { JulianDays } from "./common";
import { HistoricalDate } from './historical-date';
import { JulianDate } from "./julian-date";
export declare class GregorianDate extends HistoricalDate {
    readonly year: number | undefined;
    readonly month: number | undefined;
    readonly day: number | undefined;
    readonly isLeapYear: boolean;
    constructor(year: number | undefined, month: number | undefined, day: number | undefined);
    static fromJulianDays(jd: JulianDays): GregorianDate;
    static fromString(text: string): GregorianDate;
    addDays(days: number): GregorianDate;
    toGregorian(): this;
    toJulian(): JulianDate;
    toString(): string;
    /**
     * Gregorian to Julian Day Count for years between 1801-2099
     * @see http://quasar.as.utexas.edu/BillInfo/JulianDatesG.html
     */
    private static toJulianDays1801;
    private static toJulianDays;
    private toJulianDays;
    /**
     * Check if this is a legal date in the Gregorian calendar
     */
    private assertLegalDate;
}