export declare class WidgetValidationError extends Error {
    name: string;
    constructor(message: string);
}
/**
 * Asserts that the given input string only contains the characters specified by `legalCharacters`.
 * @param input The string under test
 * @param legalCharacters The characters that the input string may contain. Follows character class notation from regex (inside the [])
 * @param message The message that is included in the error. Specify where the input is used and can be corrected.
 * @throws WidgetValidationError If the input contains characters not allowed by legalCharacters
 */
export declare function throwOnIllegalChars(input: string, legalCharacters: string, message: string): void;
/**
 * Asserts that the given input string matches the given pattern.
 * @param input The string under test
 * @param pattern The pattern the input must match
 * @param message The message that is included in the error. Specify where the input is used and can be corrected.
 * @throws WidgetValidationError If the input contains characters not allowed by legalCharacters
 */
export declare function throwOnNoMatch(input: string, pattern: RegExp, message: string): void;