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