import { PipeTransform } from '@angular/core';
import { Observable } from 'rxjs';
import * as i0 from "@angular/core";
/**
 * Pipe that formats a string '{0} of {1}' with the given parameters
 */
export declare class LfFieldGroupIndexDisplayPipe implements PipeTransform {
    constructor();
    /**
     * Formats the given string with the two expected params
     * @param res_0_of_1 Localized string in the form '{0} of {1}'
     * @param currentIndex The current index of the group (0-indexed)
     * @param totalNumber The total number of groups
     * @returns The string formatted with the given numbers. Adds one to the current index.
     * Returns undefined if the string does not contain 2 params
     */
    transform(res_0_of_1: Observable<string>, currentIndex: number, totalNumber: number): Observable<string>;
    static ɵfac: i0.ɵɵFactoryDeclaration<LfFieldGroupIndexDisplayPipe, never>;
    static ɵpipe: i0.ɵɵPipeDeclaration<LfFieldGroupIndexDisplayPipe, "lfFieldGroupIndexDisplay", false>;
}