Rule = function(parent, $el) {
    if (!(this instanceof Rule)) {
        return new Rule(parent, $el);
    }

    Node.call(this, parent, $el);

    this._updating_value = false;
    this._updating_input = false;

    /**
     * @name filter
     * @member {QueryBuilder.Filter}
     * @memberof Rule
     * @instance
     */
    this.__.filter = null;

    /**
     * @name operator
     * @member {QueryBuilder.Operator}
     * @memberof Rule
     * @instance
     */
    this.__.operator = null;

    /**
     * @name value
     * @member {*}
     * @memberof Rule
     * @instance
     */
    this.__.value = undefined;
}
Rule object
@constructor
@extends Node
@param {Group} parent
@param {jQuery} $el