/**
 * Comparison function for sorting purposes.
 *
 * @param {*} a The first value to compare.
 * @param {*} b The second value to compare.
 * @returns {number} Returns number from -1 to 1.
 */
export declare function sortComparison(a: unknown, b: unknown): number;
/**
 * Convert raw value into visual value.
 *
 * @param {*} value The value to convert.
 * @param {string} defaultEmptyValue Default value for empty cells.
 * @returns {*}
 */
export declare function toVisualValue(value: unknown, defaultEmptyValue: string): unknown;
/**
 * Create an array assertion to compare if an element exists in that array (in a more efficient way than .indexOf).
 *
 * @param {Array} initialData Values to compare.
 * @returns {Function}
 */
export declare function createArrayAssertion(initialData: unknown[]): (value: unknown) => boolean;
export declare function toEmptyString(value: null | undefined): '';
export declare function toEmptyString<T>(value: T): T;
/**
 * Unify column values (remove duplicated values and sort them).
 *
 * @param {Array} values An array of values.
 * @param {Function} [comparator] Optional sort comparator. When omitted, numbers sort numerically
 *   and all other values sort lexicographically.
 * @returns {Array}
 */
export declare function unifyColumnValues(values: unknown[], comparator?: (a: unknown, b: unknown) => number): unknown[];
/**
 * Intersect 'base' values with 'selected' values and return an array of object.
 *
 * @param {Array} base An array of base values.
 * @param {Array} selected An array of selected values.
 * @param {string} defaultEmptyValue Default value for empty cells.
 * @param {Function} [callback] A callback function which is invoked for every item in an array.
 * @returns {Array}
 */
export declare function intersectValues(base: unknown[], selected: unknown[], defaultEmptyValue: string, callback?: Function): Record<string, unknown>[];