diff --git a/src/operator/last.ts b/src/operator/last.ts index 04a298964b..d78a0a3e62 100644 --- a/src/operator/last.ts +++ b/src/operator/last.ts @@ -1,7 +1,5 @@ import { Observable } from '../Observable'; -import { Operator } from '../Operator'; -import { Subscriber } from '../Subscriber'; -import { EmptyError } from '../util/EmptyError'; +import { last as higherOrder } from '../operators'; /* tslint:disable:max-line-length */ export function last(this: Observable, @@ -45,94 +43,5 @@ export function last(this: Observable, export function last(this: Observable, predicate?: (value: T, index: number, source: Observable) => boolean, resultSelector?: ((value: T, index: number) => R) | void, defaultValue?: R): Observable { - return this.lift(new LastOperator(predicate, resultSelector, defaultValue, this)); -} - -class LastOperator implements Operator { - constructor(private predicate?: (value: T, index: number, source: Observable) => boolean, - private resultSelector?: ((value: T, index: number) => R) | void, - private defaultValue?: any, - private source?: Observable) { - } - - call(observer: Subscriber, source: any): any { - 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 { - private lastValue: T | R; - private hasValue: boolean = false; - private index: number = 0; - - constructor(destination: Subscriber, - private predicate?: (value: T, index: number, source: Observable) => boolean, - private resultSelector?: ((value: T, index: number) => R) | void, - private defaultValue?: any, - private source?: Observable) { - super(destination); - if (typeof defaultValue !== 'undefined') { - this.lastValue = defaultValue; - this.hasValue = true; - } - } - - protected _next(value: T): void { - 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; - } - } - - private _tryPredicate(value: T, index: number) { - let result: any; - 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; - } - } - - private _tryResultSelector(value: T, index: number) { - let result: any; - try { - result = (this).resultSelector(value, index); - } catch (err) { - this.destination.error(err); - return; - } - this.lastValue = result; - this.hasValue = true; - } - - protected _complete(): void { - const destination = this.destination; - if (this.hasValue) { - destination.next(this.lastValue); - destination.complete(); - } else { - destination.error(new EmptyError); - } - } + return higherOrder(predicate, resultSelector as any, defaultValue)(this); } diff --git a/src/operators/index.ts b/src/operators/index.ts index 72e484cf17..8c86794819 100644 --- a/src/operators/index.ts +++ b/src/operators/index.ts @@ -32,6 +32,7 @@ export { first } from './first'; export { groupBy } from './groupBy'; export { ignoreElements } from './ignoreElements'; export { isEmpty } from './isEmpty'; +export { last } from './last'; export { map } from './map'; export { materialize } from './materialize'; export { max } from './max'; diff --git a/src/operators/last.ts b/src/operators/last.ts new file mode 100644 index 0000000000..a6891c02cb --- /dev/null +++ b/src/operators/last.ts @@ -0,0 +1,133 @@ +import { Observable } from '../Observable'; +import { Operator } from '../Operator'; +import { Subscriber } from '../Subscriber'; +import { EmptyError } from '../util/EmptyError'; +import { OperatorFunction, MonoTypeOperatorFunction } from '../interfaces'; + +/* tslint:disable:max-line-length */ +export function last(predicate: (value: T, index: number, source: Observable) => value is S): OperatorFunction; +export function last(predicate: (value: T | S, index: number, source: Observable) => value is S, + resultSelector: (value: S, index: number) => R, defaultValue?: R): OperatorFunction; +export function last(predicate: (value: T, index: number, source: Observable) => value is S, + resultSelector: void, + defaultValue?: S): OperatorFunction; +export function last(predicate?: (value: T, index: number, source: Observable) => boolean): MonoTypeOperatorFunction; +export function last(predicate: (value: T, index: number, source: Observable) => boolean, + resultSelector?: (value: T, index: number) => R, + defaultValue?: R): OperatorFunction; +export function last(predicate: (value: T, index: number, source: Observable) => boolean, + resultSelector: void, + defaultValue?: T): MonoTypeOperatorFunction; +/* 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. + * + * + * + * @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?: (value: T, index: number, source: Observable) => boolean, + resultSelector?: ((value: T, index: number) => R) | void, + defaultValue?: R): OperatorFunction { + return (source: Observable) => source.lift(new LastOperator(predicate, resultSelector, defaultValue, source)); +} + +class LastOperator implements Operator { + constructor(private predicate?: (value: T, index: number, source: Observable) => boolean, + private resultSelector?: ((value: T, index: number) => R) | void, + private defaultValue?: any, + private source?: Observable) { + } + + call(observer: Subscriber, source: any): any { + 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 { + private lastValue: T | R; + private hasValue: boolean = false; + private index: number = 0; + + constructor(destination: Subscriber, + private predicate?: (value: T, index: number, source: Observable) => boolean, + private resultSelector?: ((value: T, index: number) => R) | void, + private defaultValue?: any, + private source?: Observable) { + super(destination); + if (typeof defaultValue !== 'undefined') { + this.lastValue = defaultValue; + this.hasValue = true; + } + } + + protected _next(value: T): void { + 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; + } + } + + private _tryPredicate(value: T, index: number) { + let result: any; + 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; + } + } + + private _tryResultSelector(value: T, index: number) { + let result: any; + try { + result = (this).resultSelector(value, index); + } catch (err) { + this.destination.error(err); + return; + } + this.lastValue = result; + this.hasValue = true; + } + + protected _complete(): void { + const destination = this.destination; + if (this.hasValue) { + destination.next(this.lastValue); + destination.complete(); + } else { + destination.error(new EmptyError); + } + } +}