/**
 * Observer class that is attached to each observed
 * object. Once attached, the observer converts the target
 * object's property keys into getter/setters that
 * collect dependencies and dispatch updates.
 */
import Dep from "./dep";
export declare let shouldObserve: boolean;
export declare class Observer {
    value: any;
    dep: Dep;
    vmCount: number;
    constructor(value: any);
    /**
     * Walk through all properties and convert them into
     * getter/setters. This method should only be called when
     * value type is Object.
     */
    walk(obj: Object): void;
    /**
     * Observe a list of Array items.
     */
    observeArray(items: Array<any>): void;
}
/**
 * Define a reactive property on an Object.
 */
export declare function defineReactive(obj: {
    [key: string]: any;
}, key: string, val?: any, customSetter?: Function, shallow?: boolean): void;
/**
 * Attempt to create an observer instance for a value,
 * returns the new observer if successfully observed,
 * or the existing observer if the value already has one.
 */
export declare function observe(value: any, asRootData?: boolean): Observer | void;