import { Readable, Transform, TransformOptions } from 'stream';
export interface PeekStreamOptions extends TransformOptions {
    peekBytes: number;
}
export declare class BufferPeekStream extends Transform {
    private peekBytes;
    private buffer;
    private bufferLength;
    private peeked;
    constructor(options: PeekStreamOptions);
    _transform(chunk: any, encoding: BufferEncoding, callback: Function): void;
    _flush(callback: Function): void;
}
export declare function peek(source: Readable, bytes: number, callback?: (err: Error | null, buffer: Buffer, dest: BufferPeekStream) => void): BufferPeekStream;
export declare function peek(source: Readable, callback: (err: Error | null, buffer: Buffer, dest: BufferPeekStream) => void): BufferPeekStream;
export declare namespace peek {
    var promise: (source: Readable, bytes?: number) => Promise<[Buffer, BufferPeekStream]>;
}
export type PeekCallback = (err: Error | null, buffer: Buffer, dest: BufferPeekStream) => void;
export type PeekPromise = (source: Readable, bytes?: number) => Promise<[Buffer, BufferPeekStream]>;