/**
 * Utility class for requesting a specific RDF version from the backend through the <code>Accept</code> header.
 *
 * The version is announced with the <code>version</code> media type parameter, as defined by RDF 1.2.
 */
export declare class RdfVersionUtil {
    /**
     * The RDF version the workbench requests from the backend.
     */
    static readonly VERSION = "1.2";
    /**
     * Media types which are not RDF or SPARQL results formats, so the version parameter is meaningless for them.
     * <code>text/plain</code> is deliberately not here, because it is also the media type of N-Triples.
     */
    private static readonly NON_RDF_MEDIA_TYPES;
    private static readonly VERSION_PARAM;
    private static readonly WEIGHT_PARAM;
    /**
     * Adds the RDF version parameter to every RDF media range of an <code>Accept</code> header value.
     *
     * The parameter is placed right after the media type parameters and before the weight (<code>q</code>),
     * because anything after the weight is not a media type parameter. Media ranges which already
     * declare a version and non-RDF media types are left untouched, so calling this more than once is safe.
     *
     * @param accept - The <code>Accept</code> header value. May contain several comma-separated media ranges.
     * @returns The header value with the version added, or the original value if it is empty.
     *
     * @example
     * RdfVersionUtil.withVersion('application/sparql-results+json;q=0.9, *\/*;q=0.8');
     * // Returns: 'application/sparql-results+json;version=1.2;q=0.9, *\/*;version=1.2;q=0.8'
     */
    static withVersion(accept: string): string;
    static withVersion(accept: string | undefined): string | undefined;
    private static addVersionToMediaRange;
}