import { UntypedFormControl, FormGroupDirective, NgForm } from '@angular/forms';
import { ErrorStateMatcher } from '@angular/material/core';
export declare class SurveyErrorStateMatcher implements ErrorStateMatcher {
    item: any;
    isErrorState(control: UntypedFormControl | null, form: FormGroupDirective | NgForm | null): boolean;
}
export declare class ItemOptionStateMatcher implements ErrorStateMatcher {
    isErrorState(control: UntypedFormControl, form: FormGroupDirective | NgForm): boolean;
}