+++ /dev/null
-import {Observable} from '../Observable';
-import {Operator} from '../Operator';
-import {Subscriber} from '../Subscriber';
-import {OperatorFunction} from '../types';
-
-export function find<T, S extends T>(predicate: (value: T, index: number, source: Observable<T>) => value is S,
- thisArg?: any): OperatorFunction<T, S | undefined>;
-export function find<T>(predicate: (value: T, index: number, source: Observable<T>) => boolean,
- thisArg?: any): OperatorFunction<T, T | undefined>;
-/**
- * Emits only the first value emitted by the source Observable that meets some
- * condition.
- *
- * <span class="informal">Finds the first value that passes some test and emits
- * that.</span>
- *
- * ![](find.png)
- *
- * `find` searches for the first item in the source Observable that matches the
- * specified condition embodied by the `predicate`, and returns the first
- * occurrence in the source. Unlike {@link first}, the `predicate` is required
- * in `find`, and does not emit an error if a valid value is not found.
- *
- * ## Example
- * Find and emit the first click that happens on a DIV element
- * ```ts
- * import { fromEvent } from 'rxjs';
- * import { find } from 'rxjs/operators';
- *
- * const clicks = fromEvent(document, 'click');
- * const result = clicks.pipe(find(ev => ev.target.tagName === 'DIV'));
- * result.subscribe(x => console.log(x));
- * ```
- *
- * @see {@link filter}
- * @see {@link first}
- * @see {@link findIndex}
- * @see {@link take}
- *
- * @param {function(value: T, index: number, source: Observable<T>): boolean} predicate
- * A function called with each item to test for condition matching.
- * @param {any} [thisArg] An optional argument to determine the value of `this`
- * in the `predicate` function.
- * @return {Observable<T>} An Observable of the first item that matches the
- * condition.
- * @method find
- * @owner Observable
- */
-export function find<T>(predicate: (value: T, index: number, source: Observable<T>) => boolean,
- thisArg?: any): OperatorFunction<T, T | undefined> {
- if (typeof predicate !== 'function') {
- throw new TypeError('predicate is not a function');
- }
- return (source: Observable<T>) => source.lift(new FindValueOperator(predicate, source, false, thisArg)) as Observable<T | undefined>;
-}
-
-export class FindValueOperator<T> implements Operator<T, T | number | undefined> {
- constructor(private predicate: (value: T, index: number, source: Observable<T>) => boolean,
- private source: Observable<T>,
- private yieldIndex: boolean,
- private thisArg?: any) {
- }
-
- call(observer: Subscriber<T>, source: any): any {
- return source.subscribe(new FindValueSubscriber(observer, this.predicate, this.source, this.yieldIndex, this.thisArg));
- }
-}
-
-/**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
-export class FindValueSubscriber<T> extends Subscriber<T> {
- private index: number = 0;
-
- constructor(destination: Subscriber<T>,
- private predicate: (value: T, index: number, source: Observable<T>) => boolean,
- private source: Observable<T>,
- private yieldIndex: boolean,
- private thisArg?: any) {
- super(destination);
- }
-
- private notifyComplete(value: any): void {
- const destination = this.destination;
-
- destination.next(value);
- destination.complete();
- this.unsubscribe();
- }
-
- protected _next(value: T): void {
- const {predicate, thisArg} = this;
- const index = this.index++;
- try {
- const result = predicate.call(thisArg || this, value, index, this.source);
- if (result) {
- this.notifyComplete(this.yieldIndex ? index : value);
- }
- } catch (err) {
- this.destination.error(err);
- }
- }
-
- protected _complete(): void {
- this.notifyComplete(this.yieldIndex ? -1 : undefined);
- }
-}