import { Operator } from '../Operator';
import { Subscriber } from '../Subscriber';
import { OperatorFunction } from '../types';
/**
 * Applies a given `project` function to each value emitted by the source
 * Observable, and emits the resulting values as an Observable.
 *
 * <span class="informal">Like [Array.prototype.map()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map),
 * it passes each source value through a transformation function to get
 * corresponding output values.</span>
 *
 * ![](map.png)
 *
 * Similar to the well known `Array.prototype.map` function, this operator
 * applies a projection to each value and emits that projection in the output
 * Observable.
 *
 * ## Example
 * Map every click to the clientX position of that click
 * ```javascript
 * const clicks = fromEvent(document, 'click');
 * const positions = clicks.pipe(map(ev => ev.clientX));
 * positions.subscribe(x => console.log(x));
 * ```
 *
 * @see {@link mapTo}
 * @see {@link pluck}
 *
 * @param {function(value: T, index: number): R} project The function to apply
 * to each `value` emitted by the source Observable. The `index` parameter is
 * the number `i` for the i-th emission that has happened since the
 * subscription, starting from the number `0`.
 * @param {any} [thisArg] An optional argument to define what `this` is in the
 * `project` function.
 * @return {Observable<R>} An Observable that emits the values from the source
 * Observable transformed by the given `project` function.
 * @method map
 * @owner Observable
 */
export declare function map<T, R>(project: (value: T, index: number) => R, thisArg?: any): OperatorFunction<T, R>;
export declare class MapOperator<T, R> implements Operator<T, R> {
    private project;
    private thisArg;
    constructor(project: (value: T, index: number) => R, thisArg: any);
    call(subscriber: Subscriber<R>, source: any): any;
}