/**
 * Copyright © 2019 Cenacle Research India Private Limited.
 * All Rights Reserved.
 */
export type TTag = string;
export type THelp = string;
export interface ISingleton<TResult> {
    p: Promise<TResult>;
    help: THelp;
}
export type TPromiseGroup<TResult> = Map<TTag, ISingleton<TResult>>;
export declare function getNewPromiseGroup<TResult>(): TPromiseGroup<TResult>;
/**
 * Caches and returns the same promise on repeated calls.
 * The value resolved by the promise will be static and does not vary.
 * Use the `reset` method to reinitialize the promise.
 *
 * @template TResult
 * @param {() => Promise<TResult>} fn - Function that creates the promise
 * @param {TTag} tag - Unique identifier for the singleton
 * @param {THelp} help - Descriptive help text, if any, for UI purposes
 * @param {TPromiseGroup<unknown>} [promiseGroup=gPromises] - Group to store singletons
 * @returns {Promise<TResult>} The singleton promise
 */
export declare function singletonPromise<TResult>(fn: () => Promise<TResult>, tag: TTag, help?: THelp, promiseGroup?: TPromiseGroup<unknown>): Promise<TResult>;
/**
 * Resets the promises so that next time when they are called, they will
 * initialize all over again instead of returning cached values. Useful
 * to reload the data associated with the promises when the underlying
 * configuration parameters change.
 * @param {String | Array} tag the promises that need to be reset.
 */
export declare function reset(tag?: TTag | Array<TTag> | null, promiseGroup?: TPromiseGroup<unknown>): boolean | void | boolean[];
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