/// <reference types="node" />
/**
 * 2048 bits Bloom filter
 */
export declare class Bloom {
    /** number of hash functions */
    static readonly MAX_K = 16;
    /** bit length */
    static readonly BITS_LENGTH = 2048;
    /** estimate k(number of hash functions) according to item count */
    static estimateK(itemCount: number): number;
    readonly bits: Buffer;
    readonly k: number;
    /**
     * new bloom filter instance
     * @param k number of hash functions
     * @param bits leave it out to construct an empty one
     */
    constructor(k: number, bits?: Buffer);
    /**
     * add item
     * @param item
     */
    add(item: Buffer): void;
    /**
     * test if an item contained. (false positive)
     * @param item
     */
    test(item: Buffer): boolean;
    private distribute;
}