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							- 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` 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);
 
-   }
 
- }
 
 
  |