import { Expression } from '../../core/expression';
import { PipeOperator } from '../../core/pipe-operator';
import { ObjectValueSelector, ObjectValueSelectorType } from '../../helpers/object-value-selector';
import { Error } from '../../types/utils';
export declare class FlatMapOperator implements PipeOperator {
    readonly mapper: (input: Expression<any>) => Expression;
    static readonly inputIdentifier: unique symbol;
    constructor(mapper: (input: Expression<any>) => Expression);
    instantiate(input: Expression): Expression<any>;
}
export declare function flatMap<TIn extends unknown[], TOut extends unknown[]>(selector: PipeOperator<TIn[number], TOut | undefined>): PipeOperator<TIn, TOut>;
export declare function flatMap<TIn extends unknown[], TSelector extends ObjectValueSelector<TIn[number]>>(selector: ObjectValueSelectorType<TIn[number], TSelector> extends unknown[] | undefined ? TSelector : Error<'Selected value must be an array.'>): PipeOperator<TIn, NonNullable<ObjectValueSelectorType<TIn[number], TSelector>>>;