Interface Validator

packages/forms/src/directives/validators.ts:91–110

 * @publicApi
 */
export interface Validator {
  /**
   * @description
   * Method that performs synchronous validation against the provided control.
   *
   * @param control The control to validate against.
   *
   * @returns A map of validation errors if validation fails,
   * otherwise null.
   */
  validate(control: AbstractControl): ValidationErrors | null;

  /**
   * @description
   * Registers a callback function to call when the validator inputs change.
   *
   * @param fn The callback function
   */
  registerOnValidatorChange?(fn: () => void): void;
}

/**
 * A base class for Validator-based Directives. The class contains common logic shared across such