/**
 * Tolerant date parsing and calendar-delta helpers for the date detector.
 *
 * The detector needs to (a) recognize whether source values are dates, (b) keep
 * the *input shape* so output matches (a `Date` column emits `Date`s, an
 * ISO-string column emits ISO strings), and (c) classify the step between
 * consecutive dates as a whole number of days, months or years.
 *
 * @packageDocumentation
 */
/** Milliseconds in one calendar day. */
export declare const DAY_MS = 86400000;
/** How a parsed date was represented in the source, so output can match it. */
export declare enum DateShape {
    /** A native `Date` object. */
    DateObject = "date",
    /** An ISO `YYYY-MM-DD` string. */
    IsoDate = "iso-date"
}
/** A source value parsed into a date plus the shape it arrived in. */
export interface ParsedDate {
    /** Local-time date (time component zeroed for date-only shapes). */
    readonly date: Date;
    /** The representation to emit back. */
    readonly shape: DateShape;
}
/**
 * Parses a source value into a {@link ParsedDate}, or `null` when it is not a
 * date this detector handles (native `Date` or ISO `YYYY-MM-DD` string).
 *
 * @param value - The source value.
 * @returns The parsed date + shape, or `null`.
 */
export declare function parseDate(value: unknown): ParsedDate | null;
/**
 * Formats a `Date` back into the requested shape.
 *
 * @param date  - The date to emit.
 * @param shape - The representation to produce.
 * @returns A `Date` or an ISO `YYYY-MM-DD` string.
 */
export declare function formatDate(date: Date, shape: DateShape): Date | string;
/** Whole-calendar-months between two dates when day-of-month is preserved, else `null`. */
export declare function wholeMonthsBetween(a: Date, b: Date): number | null;
/** Whole-calendar-years between two dates when month/day are preserved, else `null`. */
export declare function wholeYearsBetween(a: Date, b: Date): number | null;
/** Whole days between two local dates when the gap is an exact day multiple, else `null`. */
export declare function wholeDaysBetween(a: Date, b: Date): number | null;
/**
 * Adds `n` calendar months to a date, clamping the day to the target month's
 * length (Jan 31 + 1mo → Feb 28/29), matching spreadsheet behavior.
 */
export declare function addMonths(date: Date, n: number): Date;
/** Adds `n` calendar years, clamping Feb 29 to Feb 28 on non-leap targets. */
export declare function addYears(date: Date, n: number): Date;
/** Adds `n` days (may be negative) to a date. */
export declare function addDays(date: Date, n: number): Date;
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