import { Changes, ChangeSet } from './types';
import { Component } from './component';
export declare const animatingKey = "$$animating";
/**
 * Creates fast object
 */
export declare function obj(proto?: any): Record<string, unknown>;
/**
 * Check if given value id defined, e.g. not `null`, `undefined` or `NaN`
 */
export declare function isDefined(value: unknown): boolean;
/**
 * Creates object for storing change sets, e.g. current and previous values
 */
export declare function changeSet(): ChangeSet;
/**
 * Returns properties from `next` which were changed since `prev` state.
 * Returns `null` if there are no changes
 */
export declare function changed(next: Record<string, unknown>, prev: Record<string, unknown>, prefix?: string): Changes | null;
/**
 * Adds given `scope` attribute to `el` to isolate its CSS
 */
export declare function cssScope(el: HTMLElement, host?: Component): HTMLElement;
declare const assign: {
    <T extends {}, U>(target: T, source: U): T & U;
    <T_1 extends {}, U_1, V>(target: T_1, source1: U_1, source2: V): T_1 & U_1 & V;
    <T_2 extends {}, U_2, V_1, W>(target: T_2, source1: U_2, source2: V_1, source3: W): T_2 & U_2 & V_1 & W;
    (target: object, ...sources: any[]): any;
};
/**
 * Returns property descriptors from given object
 */
declare const getObjectDescriptors: <T>(o: T) => { [P in keyof T]: TypedPropertyDescriptor<T[P]>; } & {
    [x: string]: PropertyDescriptor;
};
export { assign, getObjectDescriptors };
/**
 * Assign data from `next` to `prev` if there are any updates
 * @return Returns `true` if data was assigned
 */
export declare function assignIfNeeded(prev: Record<string, unknown>, next: Record<string, unknown>): boolean;
export declare function safeCall<T, U, Y>(fn?: (p1?: T, p2?: U) => Y, arg1?: T, arg2?: U): Y | undefined;
export declare function captureError<T, U, Y>(host: Component, fn?: (p1?: T, p2?: U) => Y, arg1?: T, arg2?: U): Y | undefined;
export declare function runtimeError(host: Component, error: Error): void;
/**
 * Schedule a microtask
 */
export declare const nextTick: typeof queueMicrotask;