| import { Subscriber } from '../Subscriber'; |
| import { tryCatch } from '../util/tryCatch'; |
| import { errorObject } from '../util/errorObject'; |
| /* tslint:enable:max-line-length */ |
| /** |
| * Returns an Observable that emits all items emitted by the source Observable that are distinct by comparison from the previous item. |
| * |
| * If a comparator function is provided, then it will be called for each item to test for whether or not that value should be emitted. |
| * |
| * If a comparator function is not provided, an equality check is used by default. |
| * |
| * @example <caption>A simple example with numbers</caption> |
| * Observable.of(1, 1, 2, 2, 2, 1, 1, 2, 3, 3, 4) |
| * .distinctUntilChanged() |
| * .subscribe(x => console.log(x)); // 1, 2, 1, 2, 3, 4 |
| * |
| * @example <caption>An example using a compare function</caption> |
| * interface Person { |
| * age: number, |
| * name: string |
| * } |
| * |
| * Observable.of<Person>( |
| * { age: 4, name: 'Foo'}, |
| * { age: 7, name: 'Bar'}, |
| * { age: 5, name: 'Foo'}) |
| * { age: 6, name: 'Foo'}) |
| * .distinctUntilChanged((p: Person, q: Person) => p.name === q.name) |
| * .subscribe(x => console.log(x)); |
| * |
| * // displays: |
| * // { age: 4, name: 'Foo' } |
| * // { age: 7, name: 'Bar' } |
| * // { age: 5, name: 'Foo' } |
| * |
| * @see {@link distinct} |
| * @see {@link distinctUntilKeyChanged} |
| * |
| * @param {function} [compare] Optional comparison function called to test if an item is distinct from the previous item in the source. |
| * @return {Observable} An Observable that emits items from the source Observable with distinct values. |
| * @method distinctUntilChanged |
| * @owner Observable |
| */ |
| export function distinctUntilChanged(compare, keySelector) { |
| return (source) => source.lift(new DistinctUntilChangedOperator(compare, keySelector)); |
| } |
| class DistinctUntilChangedOperator { |
| constructor(compare, keySelector) { |
| this.compare = compare; |
| this.keySelector = keySelector; |
| } |
| call(subscriber, source) { |
| return source.subscribe(new DistinctUntilChangedSubscriber(subscriber, this.compare, this.keySelector)); |
| } |
| } |
| /** |
| * We need this JSDoc comment for affecting ESDoc. |
| * @ignore |
| * @extends {Ignored} |
| */ |
| class DistinctUntilChangedSubscriber extends Subscriber { |
| constructor(destination, compare, keySelector) { |
| super(destination); |
| this.keySelector = keySelector; |
| this.hasKey = false; |
| if (typeof compare === 'function') { |
| this.compare = compare; |
| } |
| } |
| compare(x, y) { |
| return x === y; |
| } |
| _next(value) { |
| const keySelector = this.keySelector; |
| let key = value; |
| if (keySelector) { |
| key = tryCatch(this.keySelector)(value); |
| if (key === errorObject) { |
| return this.destination.error(errorObject.e); |
| } |
| } |
| let result = false; |
| if (this.hasKey) { |
| result = tryCatch(this.compare)(this.key, key); |
| if (result === errorObject) { |
| return this.destination.error(errorObject.e); |
| } |
| } |
| else { |
| this.hasKey = true; |
| } |
| if (Boolean(result) === false) { |
| this.key = key; |
| this.destination.next(value); |
| } |
| } |
| } |
| //# sourceMappingURL=distinctUntilChanged.js.map |