| import { OuterSubscriber } from '../OuterSubscriber'; |
| import { subscribeToResult } from '../util/subscribeToResult'; |
| import { Set } from '../util/Set'; |
| /** |
| * Returns an Observable that emits all items emitted by the source Observable that are distinct by comparison from previous items. |
| * |
| * If a keySelector function is provided, then it will project each value from the source observable into a new value that it will |
| * check for equality with previously projected values. If a keySelector function is not provided, it will use each value from the |
| * source observable directly with an equality check against previous values. |
| * |
| * In JavaScript runtimes that support `Set`, this operator will use a `Set` to improve performance of the distinct value checking. |
| * |
| * In other runtimes, this operator will use a minimal implementation of `Set` that relies on an `Array` and `indexOf` under the |
| * hood, so performance will degrade as more values are checked for distinction. Even in newer browsers, a long-running `distinct` |
| * use might result in memory leaks. To help alleviate this in some scenarios, an optional `flushes` parameter is also provided so |
| * that the internal `Set` can be "flushed", basically clearing it of values. |
| * |
| * @example <caption>A simple example with numbers</caption> |
| * Observable.of(1, 1, 2, 2, 2, 1, 2, 3, 4, 3, 2, 1) |
| * .distinct() |
| * .subscribe(x => console.log(x)); // 1, 2, 3, 4 |
| * |
| * @example <caption>An example using a keySelector function</caption> |
| * interface Person { |
| * age: number, |
| * name: string |
| * } |
| * |
| * Observable.of<Person>( |
| * { age: 4, name: 'Foo'}, |
| * { age: 7, name: 'Bar'}, |
| * { age: 5, name: 'Foo'}) |
| * .distinct((p: Person) => p.name) |
| * .subscribe(x => console.log(x)); |
| * |
| * // displays: |
| * // { age: 4, name: 'Foo' } |
| * // { age: 7, name: 'Bar' } |
| * |
| * @see {@link distinctUntilChanged} |
| * @see {@link distinctUntilKeyChanged} |
| * |
| * @param {function} [keySelector] Optional function to select which value you want to check as distinct. |
| * @param {Observable} [flushes] Optional Observable for flushing the internal HashSet of the operator. |
| * @return {Observable} An Observable that emits items from the source Observable with distinct values. |
| * @method distinct |
| * @owner Observable |
| */ |
| export function distinct(keySelector, flushes) { |
| return (source) => source.lift(new DistinctOperator(keySelector, flushes)); |
| } |
| class DistinctOperator { |
| constructor(keySelector, flushes) { |
| this.keySelector = keySelector; |
| this.flushes = flushes; |
| } |
| call(subscriber, source) { |
| return source.subscribe(new DistinctSubscriber(subscriber, this.keySelector, this.flushes)); |
| } |
| } |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| export class DistinctSubscriber extends OuterSubscriber { |
| constructor(destination, keySelector, flushes) { |
| super(destination); |
| this.keySelector = keySelector; |
| this.values = new Set(); |
| if (flushes) { |
| this.add(subscribeToResult(this, flushes)); |
| } |
| } |
| notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) { |
| this.values.clear(); |
| } |
| notifyError(error, innerSub) { |
| this._error(error); |
| } |
| _next(value) { |
| if (this.keySelector) { |
| this._useKeySelector(value); |
| } |
| else { |
| this._finalizeNext(value, value); |
| } |
| } |
| _useKeySelector(value) { |
| let key; |
| const { destination } = this; |
| try { |
| key = this.keySelector(value); |
| } |
| catch (err) { |
| destination.error(err); |
| return; |
| } |
| this._finalizeNext(key, value); |
| } |
| _finalizeNext(key, value) { |
| const { values } = this; |
| if (!values.has(key)) { |
| values.add(key); |
| this.destination.next(value); |
| } |
| } |
| } |
| //# sourceMappingURL=distinct.js.map |