import { Query } from './index';
import { RunQueryOptions, RunQueryResponse } from './query';
import { RequestCallback } from './request';
declare const AGGREGATE_QUERY: unique symbol;
/**
 * An AggregateQuery is a class that can be used to obtain results from an
 * aggregate query request.
 *
 * @see {@link https://cloud.google.com/datastore/docs/aggregation-queries| Aggregation queries Reference}
 *
 * @class
 */
declare class AggregateQuery {
    type: symbol;
    aggregations: Array<AggregateField>;
    query: Query | undefined;
    /**
     * Build an AggregateQuery object.
     *
     * @param {Query} query A Query object
     */
    constructor(query: Query);
    /**
     * Add a `count` aggregate query to the list of aggregations.
     *
     * @param {string} alias The label used in the results to describe this
     * aggregate field when a query is run.
     * @returns {AggregateQuery}
     */
    count(alias?: string): AggregateQuery;
    /**
     * Add a `sum` aggregate query to the list of aggregations.
     *
     * @param {string} property The property to use for the sum calculation.
     * @param {string} alias The label used in the results to describe this
     * aggregate field when a query is run.
     * @returns {AggregateQuery}
     */
    sum(property: string, alias?: string): AggregateQuery;
    /**
     * Add a `average` aggregate query to the list of aggregations.
     *
     * @param {string} property The property to use for the average calculation.
     * @param {string} alias The label used in the results to describe this
     * aggregate field when a query is run.
     * @returns {AggregateQuery}
     */
    average(property: string, alias?: string): AggregateQuery;
    /**
     * Add a custom aggregation to the list of aggregations.
     *
     * @param {AggregateField} aggregation The aggregate field to perform the
     * aggregation query over.
     * @returns {AggregateQuery}
     */
    addAggregation(aggregation: AggregateField): AggregateQuery;
    /**
     * Add a list of custom aggregations to the list of aggregations.
     *
     * @param {AggregateField[]} aggregations The aggregate fields to perform the
     * aggregation query over.
     * @returns {AggregateQuery}
     */
    addAggregations(aggregations: AggregateField[]): AggregateQuery;
    /**
     * Run the aggregation query and return the results.
     *
     * @param {RunQueryOptions | RequestCallback} [optionsOrCallback]
     * @param {function} cb The callback function.
     * @returns {void | Promise<RunQueryResponse>}
     */
    run(optionsOrCallback?: RunQueryOptions | RequestCallback, cb?: RequestCallback): void | Promise<RunQueryResponse>;
    /**
     * Get the proto for the list of aggregations.
     *
     */
    toProto(): any;
}
/**
 * An AggregateField is a class that contains data that defines an aggregation.
 *
 */
declare abstract class AggregateField {
    alias_?: string;
    /**
     * Gets a copy of the Count aggregate field.
     *
     * @returns {Count}
     */
    static count(): Count;
    /**
     * Gets a copy of the Sum aggregate field.
     *
     * @param {string} property The property to use for the average calculation.
     * @returns {Sum}
     */
    static sum(property: string): Sum;
    /**
     * Gets a copy of the Average aggregate field.
     *
     * @param {string} property The property to use for the average calculation.
     * @returns {Average}
     */
    static average(property: string): Average;
    /**
     * Sets the alias on the aggregate field that should be used.
     *
     * @param {string} alias The label used in the results to describe this
     * aggregate field when a query is run.
     * @returns {AggregateField}
     */
    alias(alias?: string): AggregateField;
    /**
     * Gets the proto for the aggregate field.
     *
     */
    abstract toProto(): any;
}
/**
 * A Count is a class that contains data that defines a Count aggregation.
 *
 */
declare class Count extends AggregateField {
    /**
     * Gets the proto for the count aggregate field.
     *
     */
    toProto(): any;
}
/**
 * A PropertyAggregateField is a class that contains data that defines any
 * aggregation that is performed on a property.
 *
 */
declare abstract class PropertyAggregateField extends AggregateField {
    property_: string;
    abstract operator: string;
    /**
     * Build a PropertyAggregateField object.
     *
     * @param {string} property The property to aggregate over.
     */
    constructor(property_: string);
    /**
     * Gets the proto for the property aggregate field.
     *
     */
    toProto(): any;
}
/**
 * A Sum is a class that contains data that defines a Sum aggregation.
 *
 */
declare class Sum extends PropertyAggregateField {
    operator: string;
}
/**
 * An Average is a class that contains data that defines an Average aggregation.
 *
 */
declare class Average extends PropertyAggregateField {
    operator: string;
}
export { AggregateField, AggregateQuery, AGGREGATE_QUERY };