| import { Subscriber } from '../Subscriber'; |
| import { EmptyError } from '../util/EmptyError'; |
| /* tslint:enable:max-line-length */ |
| /** |
| * Returns an Observable that emits only the last item emitted by the source Observable. |
| * It optionally takes a predicate function as a parameter, in which case, rather than emitting |
| * the last item from the source Observable, the resulting Observable will emit the last item |
| * from the source Observable that satisfies the predicate. |
| * |
| * <img src="./img/last.png" width="100%"> |
| * |
| * @throws {EmptyError} Delivers an EmptyError to the Observer's `error` |
| * callback if the Observable completes before any `next` notification was sent. |
| * @param {function} predicate - The condition any source emitted item has to satisfy. |
| * @return {Observable} An Observable that emits only the last item satisfying the given condition |
| * from the source, or an NoSuchElementException if no such items are emitted. |
| * @throws - Throws if no items that match the predicate are emitted by the source Observable. |
| * @method last |
| * @owner Observable |
| */ |
| export function last(predicate, resultSelector, defaultValue) { |
| return (source) => source.lift(new LastOperator(predicate, resultSelector, defaultValue, source)); |
| } |
| class LastOperator { |
| constructor(predicate, resultSelector, defaultValue, source) { |
| this.predicate = predicate; |
| this.resultSelector = resultSelector; |
| this.defaultValue = defaultValue; |
| this.source = source; |
| } |
| call(observer, source) { |
| return source.subscribe(new LastSubscriber(observer, this.predicate, this.resultSelector, this.defaultValue, this.source)); |
| } |
| } |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| class LastSubscriber extends Subscriber { |
| constructor(destination, predicate, resultSelector, defaultValue, source) { |
| super(destination); |
| this.predicate = predicate; |
| this.resultSelector = resultSelector; |
| this.defaultValue = defaultValue; |
| this.source = source; |
| this.hasValue = false; |
| this.index = 0; |
| if (typeof defaultValue !== 'undefined') { |
| this.lastValue = defaultValue; |
| this.hasValue = true; |
| } |
| } |
| _next(value) { |
| const index = this.index++; |
| if (this.predicate) { |
| this._tryPredicate(value, index); |
| } |
| else { |
| if (this.resultSelector) { |
| this._tryResultSelector(value, index); |
| return; |
| } |
| this.lastValue = value; |
| this.hasValue = true; |
| } |
| } |
| _tryPredicate(value, index) { |
| let result; |
| try { |
| result = this.predicate(value, index, this.source); |
| } |
| catch (err) { |
| this.destination.error(err); |
| return; |
| } |
| if (result) { |
| if (this.resultSelector) { |
| this._tryResultSelector(value, index); |
| return; |
| } |
| this.lastValue = value; |
| this.hasValue = true; |
| } |
| } |
| _tryResultSelector(value, index) { |
| let result; |
| try { |
| result = this.resultSelector(value, index); |
| } |
| catch (err) { |
| this.destination.error(err); |
| return; |
| } |
| this.lastValue = result; |
| this.hasValue = true; |
| } |
| _complete() { |
| const destination = this.destination; |
| if (this.hasValue) { |
| destination.next(this.lastValue); |
| destination.complete(); |
| } |
| else { |
| destination.error(new EmptyError); |
| } |
| } |
| } |
| //# sourceMappingURL=last.js.map |