export type FrequencyWindow = {
    /** Start time in minutes since midnight */
    startTime: number;
    /** End time (exclusive) in minutes since midnight */
    endTime: number;
    /** Headway in minutes */
    headwayMins: number;
};
/**
 * A map from a GTFS trip_id to the list of frequency windows that define
 * its repeated service pattern.
 */
export type FrequenciesMap = Map<string, FrequencyWindow[]>;
/**
 * Parses the frequencies.txt file from a GTFS feed.
 *
 * In GTFS, a frequency entry indicates that a trip departs repeatedly at
 * a fixed headway between start_time and end_time. The stop times in
 * stop_times.txt for that trip serve only as a template – each stop's
 * time offset relative to the first stop is preserved, while the absolute
 * departure times are generated from the frequency windows.
 *
 * @param stream The readable stream containing the frequencies.txt data.
 * @param activeTripIds The set of active trip IDs to filter by.
 *   Only frequency entries whose trip_id appears in this set are included.
 * @returns A map of trip IDs to their ordered list of frequency windows.
 */
export declare const parseFrequencies: (stream: NodeJS.ReadableStream, activeTripIds: Set<string>) => Promise<FrequenciesMap>;