/**
 * Class for extracting XML from PDF files with robust error handling
 */
export declare class RobustPDFExtractor {
    /**
     * Extracts XML from a PDF buffer
     * @param pdfBuffer PDF buffer
     * @returns XML content or null if not found
     */
    extractXml(pdfBuffer: Uint8Array | Buffer): Promise<string | null>;
    /**
     * Standard extraction method using PDF-lib
     * @param pdfBuffer PDF buffer
     * @returns XML content or null if not found
     */
    private standardExtraction;
    /**
     * Alternative extraction method using a more robust approach
     * @param pdfBuffer PDF buffer
     * @returns XML content or null if not found
     */
    private alternativeExtraction;
    /**
     * Extracts XML from a string
     * @param pdfString PDF string
     * @returns XML content or null if not found
     */
    private extractXmlFromString;
    /**
     * Checks if an XML string is valid
     * @param xmlString XML string to check
     * @returns True if the XML is valid
     */
    private isValidXml;
    /**
     * Extracts a sample XML file for testing
     * @returns Sample XML content
     */
    private extractSampleXml;
}