[6a3a178] | 1 | import { Operator } from '../Operator';
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| 2 | import { Observable } from '../Observable';
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| 3 | import { Subscriber } from '../Subscriber';
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| 4 | import { Subscription } from '../Subscription';
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| 5 |
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| 6 | import { Observer, OperatorFunction } from '../types';
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| 7 |
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| 8 | /**
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| 9 | * Compares all values of two observables in sequence using an optional comparator function
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| 10 | * and returns an observable of a single boolean value representing whether or not the two sequences
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| 11 | * are equal.
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| 12 | *
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| 13 | * <span class="informal">Checks to see of all values emitted by both observables are equal, in order.</span>
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| 14 | *
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| 15 | * ![](sequenceEqual.png)
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| 16 | *
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| 17 | * `sequenceEqual` subscribes to two observables and buffers incoming values from each observable. Whenever either
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| 18 | * observable emits a value, the value is buffered and the buffers are shifted and compared from the bottom
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| 19 | * up; If any value pair doesn't match, the returned observable will emit `false` and complete. If one of the
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| 20 | * observables completes, the operator will wait for the other observable to complete; If the other
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| 21 | * observable emits before completing, the returned observable will emit `false` and complete. If one observable never
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| 22 | * completes or emits after the other complets, the returned observable will never complete.
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| 23 | *
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| 24 | * ## Example
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| 25 | * figure out if the Konami code matches
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| 26 | * ```ts
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| 27 | * import { from, fromEvent } from 'rxjs';
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| 28 | * import { sequenceEqual, bufferCount, mergeMap, map } from 'rxjs/operators';
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| 29 | *
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| 30 | * const codes = from([
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| 31 | * 'ArrowUp',
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| 32 | * 'ArrowUp',
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| 33 | * 'ArrowDown',
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| 34 | * 'ArrowDown',
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| 35 | * 'ArrowLeft',
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| 36 | * 'ArrowRight',
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| 37 | * 'ArrowLeft',
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| 38 | * 'ArrowRight',
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| 39 | * 'KeyB',
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| 40 | * 'KeyA',
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| 41 | * 'Enter', // no start key, clearly.
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| 42 | * ]);
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| 43 | *
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| 44 | * const keys = fromEvent(document, 'keyup').pipe(map(e => e.code));
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| 45 | * const matches = keys.pipe(
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| 46 | * bufferCount(11, 1),
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| 47 | * mergeMap(
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| 48 | * last11 => from(last11).pipe(sequenceEqual(codes)),
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| 49 | * ),
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| 50 | * );
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| 51 | * matches.subscribe(matched => console.log('Successful cheat at Contra? ', matched));
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| 52 | * ```
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| 53 | *
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| 54 | * @see {@link combineLatest}
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| 55 | * @see {@link zip}
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| 56 | * @see {@link withLatestFrom}
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| 57 | *
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| 58 | * @param {Observable} compareTo The observable sequence to compare the source sequence to.
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| 59 | * @param {function} [comparator] An optional function to compare each value pair
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| 60 | * @return {Observable} An Observable of a single boolean value representing whether or not
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| 61 | * the values emitted by both observables were equal in sequence.
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| 62 | * @method sequenceEqual
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| 63 | * @owner Observable
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| 64 | */
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| 65 | export function sequenceEqual<T>(compareTo: Observable<T>,
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| 66 | comparator?: (a: T, b: T) => boolean): OperatorFunction<T, boolean> {
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| 67 | return (source: Observable<T>) => source.lift(new SequenceEqualOperator(compareTo, comparator));
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| 68 | }
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| 69 |
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| 70 | export class SequenceEqualOperator<T> implements Operator<T, boolean> {
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| 71 | constructor(private compareTo: Observable<T>,
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| 72 | private comparator: (a: T, b: T) => boolean) {
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| 73 | }
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| 74 |
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| 75 | call(subscriber: Subscriber<boolean>, source: any): any {
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| 76 | return source.subscribe(new SequenceEqualSubscriber(subscriber, this.compareTo, this.comparator));
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| 77 | }
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| 78 | }
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| 79 |
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| 80 | /**
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| 81 | * We need this JSDoc comment for affecting ESDoc.
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| 82 | * @ignore
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| 83 | * @extends {Ignored}
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| 84 | */
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| 85 | export class SequenceEqualSubscriber<T, R> extends Subscriber<T> {
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| 86 | private _a: T[] = [];
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| 87 | private _b: T[] = [];
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| 88 | private _oneComplete = false;
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| 89 |
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| 90 | constructor(destination: Observer<R>,
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| 91 | private compareTo: Observable<T>,
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| 92 | private comparator: (a: T, b: T) => boolean) {
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| 93 | super(destination);
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| 94 | (this.destination as Subscription).add(compareTo.subscribe(new SequenceEqualCompareToSubscriber(destination, this)));
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| 95 | }
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| 96 |
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| 97 | protected _next(value: T): void {
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| 98 | if (this._oneComplete && this._b.length === 0) {
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| 99 | this.emit(false);
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| 100 | } else {
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| 101 | this._a.push(value);
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| 102 | this.checkValues();
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| 103 | }
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| 104 | }
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| 105 |
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| 106 | public _complete(): void {
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| 107 | if (this._oneComplete) {
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| 108 | this.emit(this._a.length === 0 && this._b.length === 0);
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| 109 | } else {
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| 110 | this._oneComplete = true;
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| 111 | }
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| 112 | this.unsubscribe();
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| 113 | }
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| 114 |
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| 115 | checkValues() {
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| 116 | const { _a, _b, comparator } = this;
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| 117 | while (_a.length > 0 && _b.length > 0) {
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| 118 | let a = _a.shift();
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| 119 | let b = _b.shift();
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| 120 | let areEqual = false;
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| 121 | try {
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| 122 | areEqual = comparator ? comparator(a, b) : a === b;
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| 123 | } catch (e) {
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| 124 | this.destination.error(e);
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| 125 | }
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| 126 | if (!areEqual) {
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| 127 | this.emit(false);
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| 128 | }
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| 129 | }
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| 130 | }
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| 131 |
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| 132 | emit(value: boolean) {
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| 133 | const { destination } = this;
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| 134 | destination.next(value);
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| 135 | destination.complete();
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| 136 | }
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| 137 |
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| 138 | nextB(value: T) {
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| 139 | if (this._oneComplete && this._a.length === 0) {
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| 140 | this.emit(false);
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| 141 | } else {
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| 142 | this._b.push(value);
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| 143 | this.checkValues();
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| 144 | }
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| 145 | }
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| 146 |
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| 147 | completeB() {
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| 148 | if (this._oneComplete) {
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| 149 | this.emit(this._a.length === 0 && this._b.length === 0);
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| 150 | } else {
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| 151 | this._oneComplete = true;
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| 152 | }
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| 153 | }
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| 154 | }
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| 155 |
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| 156 | class SequenceEqualCompareToSubscriber<T, R> extends Subscriber<T> {
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| 157 | constructor(destination: Observer<R>, private parent: SequenceEqualSubscriber<T, R>) {
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| 158 | super(destination);
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| 159 | }
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| 160 |
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| 161 | protected _next(value: T): void {
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| 162 | this.parent.nextB(value);
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| 163 | }
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| 164 |
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| 165 | protected _error(err: any): void {
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| 166 | this.parent.error(err);
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| 167 | this.unsubscribe();
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| 168 | }
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| 169 |
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| 170 | protected _complete(): void {
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| 171 | this.parent.completeB();
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| 172 | this.unsubscribe();
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| 173 | }
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| 174 | }
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