import { Writable } from 'stream';
export declare class CsvWriter<T> extends Writable {
    private columns;
    private delimiter;
    private includeHeader;
    private filePath;
    private fileStream;
    private outputBuffer;
    constructor(options?: {
        filePath?: string;
        delimiter?: string;
        includeHeader?: boolean;
    });
    _construct(callback: (error?: Error | null) => void): void;
    _write(chunk: T, _: BufferEncoding, callback: (error?: Error | null) => void): void;
    writeData(data: string, callback?: (error?: Error | null) => void): void;
    _final(callback: (error?: Error | null) => void): void;
    getOutputBuffer(): string;
}