import { MultiSetCounter } from '../index';
/**
 * Implement this interface to support the use of different hash functions. Note that
 * your backend will need to be registered using `HasherFactory.register(..)` before
 * it can be used.
 */
export interface Hasher<V> {
    /**
     * Generate hash of the provided string.
     */
    hash(val: string): V;
    /**
     * Returns the number of consecutive zeros in the provided hash value.
     * @param hashVal The hash value as computed by the `hash(..)` method.
     */
    runLength(hashVal: V): number;
    /**
     * Determine the register index for a given hash value.
     * @param hashVal The hash value as computed by the `hash(..)` method.
     */
    regIdx(hashVal: V): number;
    /**
     * Returns the length, in bits, of hash values generated by this `Hasher`.
     */
    readonly hashLen: number;
    /**
     * The unique name of this `Hasher` implementation. Used to ensure counters
     * are compatible before merging, as well as to instantiate the proper backend
     * when deserializing.
     */
    readonly hasherId: string;
    /** Maximum number of register bits supported by a `Hasher` implementation */
    readonly maxPrecision: number;
}
interface HasherFactoryImpl {
    new (counter: MultiSetCounter): Hasher<any>;
}
export declare class HasherFactory {
    private static factories;
    /**
     * Used to register custom backends so that they may be instantiated given their unique id
     * (see `Options.hasherId`). See the `Jenkins32` class for an example of how to register your backend.
     */
    static register(hasherId: string, f: HasherFactoryImpl): void;
    /**
     * Builds a `Hasher` instance given it's `hasherId` and the counter it will be used with. This is
     * used internally by `HyperLogLog` during construction and deserialization.
     */
    static build(hasherId: string, counter: MultiSetCounter): Hasher<any>;
}
export {};
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