import { IndexInterface, IndexOperation, IndexReader } from './base-index.js';
import { RangeQueryOptions } from './btree-index.js';
export declare class ReverseIndex<TKey extends string | number> implements IndexReader<TKey> {
    private readonly nullsFirst?;
    private originalIndex;
    /**
     * @param nullsFirst - Whether nullish values come first in the reversed
     * order. The original index keeps them at the opposite end, so reversing
     * it alone would move them; ordered reads put them back. Omit it to read
     * the original index's plain reversed walk, as earlier releases did.
     */
    constructor(index: IndexInterface<TKey>, nullsFirst?: boolean | undefined);
    lookup(operation: IndexOperation, value: any): Set<TKey>;
    rangeQuery(options?: RangeQueryOptions): Set<TKey>;
    take(n: number, from: any, filterFn?: (key: TKey) => boolean): Array<TKey>;
    takeFromStart(n: number, filterFn?: (key: TKey) => boolean): Array<TKey>;
    /** Reads after `from` (`null` is the nullish group), or from the start. */
    private read;
    supports(operation: IndexOperation): boolean;
    get supportsRangeOptimization(): boolean;
    canOptimizeRangeFor(value: unknown): boolean;
    get keyCount(): number;
}