import { Descriptor } from '../descriptor';
import { CallSettings } from '../gax';
import { NormalApiCaller } from '../normalCalls/normalApiCaller';
import { BundleApiCaller } from './bundleApiCaller';
/**
 * A descriptor for calls that can be bundled into one call.
 */
export declare class BundleDescriptor implements Descriptor {
    bundledField: string;
    requestDiscriminatorFields: string[];
    subresponseField: string | null;
    byteLengthFunction: Function;
    /**
     * Describes the structure of bundled call.
     *
     * requestDiscriminatorFields may include '.' as a separator, which is used to
     * indicate object traversal. This allows fields in nested objects to be used
     * to determine what request to bundle.
     *
     * @property {String} bundledField
     * @property {String} requestDiscriminatorFields
     * @property {String} subresponseField
     * @property {Function} byteLengthFunction
     *
     * @param {String} bundledField - the repeated field in the request message
     *   that will have its elements aggregated by bundling.
     * @param {String} requestDiscriminatorFields - a list of fields in the
     *   target request message class that are used to detemrine which request
     *   messages should be bundled together.
     * @param {String} subresponseField - an optional field, when present it
     *   indicates the field in the response message that should be used to
     *   demultiplex the response into multiple response messages.
     * @param {Function} byteLengthFunction - a function to obtain the byte
     *   length to be consumed for the bundled field messages. Because Node.JS
     *   protobuf.js/gRPC uses builtin Objects for the user-visible data and
     *   internally they are encoded/decoded in protobuf manner, this function
     *   is actually necessary to calculate the byte length.
     * @constructor
     */
    constructor(bundledField: string, requestDiscriminatorFields: string[], subresponseField: string | null, byteLengthFunction: Function);
    getApiCaller(settings: CallSettings): NormalApiCaller | BundleApiCaller;
}