/// <reference types="node" />
import type { Blockchain } from './blockchain';
import type { BlockHeader } from './primitives';
import { Event } from './event';
import { Logger } from './logger';
/**
 * This is used to get a non synchronous chain of block events from the blockchain
 * As blocks are added and removed, this system will call onAdd() and onRemove() in
 * a guaranteed correct order. If you have this chain:
 *      G -> A1
 *
 * You'll get
 *  - onAdd(G)
 *  - onAdd(A1)
 *
 * If you then reorg and have received
 *      G -> A1
 *        -> B1 -> B2
 *
 * - onAdd(G)
 * - onAdd(A1)
 * - onRemove(A1)
 * - onAdd(B1)
 * - onAdd(B2)
 */
export declare class ChainProcessor {
    chain: Blockchain;
    hash: Buffer | null;
    sequence: number | null;
    logger: Logger;
    onAdd: Event<[block: BlockHeader]>;
    onRemove: Event<[block: BlockHeader]>;
    maxQueueSize: number | null;
    constructor(options: {
        logger?: Logger;
        chain: Blockchain;
        head: Buffer | null;
        maxQueueSize?: number | null;
    });
    private add;
    private remove;
    update({ signal }?: {
        signal?: AbortSignal;
    }): Promise<{
        hashChanged: boolean;
    }>;
}
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