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- import { Operator } from '../Operator';
- import { Observable } from '../Observable';
- import { Subscriber } from '../Subscriber';
- import { Subscription } from '../Subscription';
- import { Observer, OperatorFunction } from '../types';
- /**
- * Compares all values of two observables in sequence using an optional comparator function
- * and returns an observable of a single boolean value representing whether or not the two sequences
- * are equal.
- *
- * <span class="informal">Checks to see of all values emitted by both observables are equal, in order.</span>
- *
- * 
- *
- * `sequenceEqual` subscribes to two observables and buffers incoming values from each observable. Whenever either
- * observable emits a value, the value is buffered and the buffers are shifted and compared from the bottom
- * up; If any value pair doesn't match, the returned observable will emit `false` and complete. If one of the
- * observables completes, the operator will wait for the other observable to complete; If the other
- * observable emits before completing, the returned observable will emit `false` and complete. If one observable never
- * completes or emits after the other complets, the returned observable will never complete.
- *
- * ## Example
- * figure out if the Konami code matches
- * ```ts
- * import { from, fromEvent } from 'rxjs';
- * import { sequenceEqual, bufferCount, mergeMap, map } from 'rxjs/operators';
- *
- * const codes = from([
- * 'ArrowUp',
- * 'ArrowUp',
- * 'ArrowDown',
- * 'ArrowDown',
- * 'ArrowLeft',
- * 'ArrowRight',
- * 'ArrowLeft',
- * 'ArrowRight',
- * 'KeyB',
- * 'KeyA',
- * 'Enter', // no start key, clearly.
- * ]);
- *
- * const keys = fromEvent(document, 'keyup').pipe(map(e => e.code));
- * const matches = keys.pipe(
- * bufferCount(11, 1),
- * mergeMap(
- * last11 => from(last11).pipe(sequenceEqual(codes)),
- * ),
- * );
- * matches.subscribe(matched => console.log('Successful cheat at Contra? ', matched));
- * ```
- *
- * @see {@link combineLatest}
- * @see {@link zip}
- * @see {@link withLatestFrom}
- *
- * @param {Observable} compareTo The observable sequence to compare the source sequence to.
- * @param {function} [comparator] An optional function to compare each value pair
- * @return {Observable} An Observable of a single boolean value representing whether or not
- * the values emitted by both observables were equal in sequence.
- * @method sequenceEqual
- * @owner Observable
- */
- export function sequenceEqual<T>(compareTo: Observable<T>,
- comparator?: (a: T, b: T) => boolean): OperatorFunction<T, boolean> {
- return (source: Observable<T>) => source.lift(new SequenceEqualOperator(compareTo, comparator));
- }
- export class SequenceEqualOperator<T> implements Operator<T, boolean> {
- constructor(private compareTo: Observable<T>,
- private comparator: (a: T, b: T) => boolean) {
- }
- call(subscriber: Subscriber<boolean>, source: any): any {
- return source.subscribe(new SequenceEqualSubscriber(subscriber, this.compareTo, this.comparator));
- }
- }
- /**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
- export class SequenceEqualSubscriber<T, R> extends Subscriber<T> {
- private _a: T[] = [];
- private _b: T[] = [];
- private _oneComplete = false;
- constructor(destination: Observer<R>,
- private compareTo: Observable<T>,
- private comparator: (a: T, b: T) => boolean) {
- super(destination);
- (this.destination as Subscription).add(compareTo.subscribe(new SequenceEqualCompareToSubscriber(destination, this)));
- }
- protected _next(value: T): void {
- if (this._oneComplete && this._b.length === 0) {
- this.emit(false);
- } else {
- this._a.push(value);
- this.checkValues();
- }
- }
- public _complete(): void {
- if (this._oneComplete) {
- this.emit(this._a.length === 0 && this._b.length === 0);
- } else {
- this._oneComplete = true;
- }
- this.unsubscribe();
- }
- checkValues() {
- const { _a, _b, comparator } = this;
- while (_a.length > 0 && _b.length > 0) {
- let a = _a.shift();
- let b = _b.shift();
- let areEqual = false;
- try {
- areEqual = comparator ? comparator(a, b) : a === b;
- } catch (e) {
- this.destination.error(e);
- }
- if (!areEqual) {
- this.emit(false);
- }
- }
- }
- emit(value: boolean) {
- const { destination } = this;
- destination.next(value);
- destination.complete();
- }
- nextB(value: T) {
- if (this._oneComplete && this._a.length === 0) {
- this.emit(false);
- } else {
- this._b.push(value);
- this.checkValues();
- }
- }
- completeB() {
- if (this._oneComplete) {
- this.emit(this._a.length === 0 && this._b.length === 0);
- } else {
- this._oneComplete = true;
- }
- }
- }
- class SequenceEqualCompareToSubscriber<T, R> extends Subscriber<T> {
- constructor(destination: Observer<R>, private parent: SequenceEqualSubscriber<T, R>) {
- super(destination);
- }
- protected _next(value: T): void {
- this.parent.nextB(value);
- }
- protected _error(err: any): void {
- this.parent.error(err);
- this.unsubscribe();
- }
- protected _complete(): void {
- this.parent.completeB();
- this.unsubscribe();
- }
- }
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