/**
 * ROWS UNDER A DAY — the one implementation of "fold a set into its days", for
 * `Itinerary` and the calendar's `CalendarAgenda` alike.
 *
 * What is NOT here is the day's HEAD: the agenda's states no year because it
 * sits under a month title that does, and an itinerary's crosses months and
 * years, so the words each device heads a day with stay with the device.
 */
/** One day's rows, in the order they are drawn. */
export interface DayRun<T> {
    /** The day's key — an ISO date, so the runs sort forward as text. */
    day: string;
    rows: readonly T[];
}
/**
 * The rows folded into their days, ascending, each day's rows in `order`.
 *
 * A row whose `day` is `null` belongs to no day and is dropped: the day head is
 * the device's subject.
 *
 * ASCENDING IS NOT AN OPTION. Ties inside a day break on ARRIVAL, so a caller's
 * order decides between two rows the comparator calls equal, and the sorts run
 * over copies: the caller's array is never touched.
 */
export declare function dayRuns<T>(rows: readonly T[], day: (row: T) => string | null, order?: (a: T, b: T) => number): DayRun<T>[];
/** A `Date`'s own day, as the key the runs are folded on. LOCAL, never
 *  `toISOString` — that is UTC, and east of Greenwich every event before 07:00
 *  files under the day before. */
export declare function dayKey(date: Date): string;
/**
 * EVERY DAY OF A WINDOW, ASCENDING AND INCLUSIVE — the run a register whose ROWS
 * ARE DAYS is drawn over.
 *
 * {@link dayRuns} folds the days a set HAS; this states the days a window has,
 * so a day nobody filed against is still drawn — the gap is what such a register
 * is read for.
 *
 * NOTHING where either end is not a date or the window is inverted. Walked at
 * NOON so a step across a daylight-saving boundary lands on the next day rather
 * than on 23:00 of the same one, and LOCAL for the reason {@link dayKey} is.
 */
export declare function calendarDays(from: string, to: string): string[];