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node_modules/rxjs/src/internal/operators/audit.ts

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+import { Operator } from '../Operator';
+import { Subscriber } from '../Subscriber';
+import { Observable } from '../Observable';
+import { Subscription } from '../Subscription';
+import { MonoTypeOperatorFunction, SubscribableOrPromise, TeardownLogic } from '../types';
+
+import { OuterSubscriber } from '../OuterSubscriber';
+import { subscribeToResult } from '../util/subscribeToResult';
+
+/**
+ * Ignores source values for a duration determined by another Observable, then
+ * emits the most recent value from the source Observable, then repeats this
+ * process.
+ *
+ * <span class="informal">It's like {@link auditTime}, but the silencing
+ * duration is determined by a second Observable.</span>
+ *
+ * ![](audit.png)
+ *
+ * `audit` is similar to `throttle`, but emits the last value from the silenced
+ * time window, instead of the first value. `audit` emits the most recent value
+ * from the source Observable on the output Observable as soon as its internal
+ * timer becomes disabled, and ignores source values while the timer is enabled.
+ * Initially, the timer is disabled. As soon as the first source value arrives,
+ * the timer is enabled by calling the `durationSelector` function with the
+ * source value, which returns the "duration" Observable. When the duration
+ * Observable emits a value or completes, the timer is disabled, then the most
+ * recent source value is emitted on the output Observable, and this process
+ * repeats for the next source value.
+ *
+ * ## Example
+ *
+ * Emit clicks at a rate of at most one click per second
+ * ```ts
+ * import { fromEvent, interval } from 'rxjs';
+ * import { audit } from 'rxjs/operators'
+ *
+ * const clicks = fromEvent(document, 'click');
+ * const result = clicks.pipe(audit(ev => interval(1000)));
+ * result.subscribe(x => console.log(x));
+ * ```
+ * @see {@link auditTime}
+ * @see {@link debounce}
+ * @see {@link delayWhen}
+ * @see {@link sample}
+ * @see {@link throttle}
+ *
+ * @param {function(value: T): SubscribableOrPromise} durationSelector A function
+ * that receives a value from the source Observable, for computing the silencing
+ * duration, returned as an Observable or a Promise.
+ * @return {Observable<T>} An Observable that performs rate-limiting of
+ * emissions from the source Observable.
+ * @method audit
+ * @owner Observable
+ */
+export function audit<T>(durationSelector: (value: T) => SubscribableOrPromise<any>): MonoTypeOperatorFunction<T> {
+  return function auditOperatorFunction(source: Observable<T>) {
+    return source.lift(new AuditOperator(durationSelector));
+  };
+}
+
+class AuditOperator<T> implements Operator<T, T> {
+  constructor(private durationSelector: (value: T) => SubscribableOrPromise<any>) {
+  }
+
+  call(subscriber: Subscriber<T>, source: any): TeardownLogic {
+    return source.subscribe(new AuditSubscriber<T, T>(subscriber, this.durationSelector));
+  }
+}
+
+/**
+ * We need this JSDoc comment for affecting ESDoc.
+ * @ignore
+ * @extends {Ignored}
+ */
+class AuditSubscriber<T, R> extends OuterSubscriber<T, R> {
+
+  private value: T;
+  private hasValue: boolean = false;
+  private throttled: Subscription;
+
+  constructor(destination: Subscriber<T>,
+              private durationSelector: (value: T) => SubscribableOrPromise<any>) {
+    super(destination);
+  }
+
+  protected _next(value: T): void {
+    this.value = value;
+    this.hasValue = true;
+    if (!this.throttled) {
+      let duration;
+      try {
+        const { durationSelector } = this;
+        duration = durationSelector(value);
+      } catch (err) {
+        return this.destination.error(err);
+      }
+      const innerSubscription = subscribeToResult(this, duration);
+      if (!innerSubscription || innerSubscription.closed) {
+        this.clearThrottle();
+      } else {
+        this.add(this.throttled = innerSubscription);
+      }
+    }
+  }
+
+  clearThrottle() {
+    const { value, hasValue, throttled } = this;
+    if (throttled) {
+      this.remove(throttled);
+      this.throttled = null;
+      throttled.unsubscribe();
+    }
+    if (hasValue) {
+      this.value = null;
+      this.hasValue = false;
+      this.destination.next(value);
+    }
+  }
+
+  notifyNext(outerValue: T, innerValue: R, outerIndex: number, innerIndex: number): void {
+    this.clearThrottle();
+  }
+
+  notifyComplete(): void {
+    this.clearThrottle();
+  }
+}