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node_modules/rxjs/_esm2015/operators/mergeScan.js

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+import { tryCatch } from '../util/tryCatch';
+import { errorObject } from '../util/errorObject';
+import { subscribeToResult } from '../util/subscribeToResult';
+import { OuterSubscriber } from '../OuterSubscriber';
+/**
+ * Applies an accumulator function over the source Observable where the
+ * accumulator function itself returns an Observable, then each intermediate
+ * Observable returned is merged into the output Observable.
+ *
+ * <span class="informal">It's like {@link scan}, but the Observables returned
+ * by the accumulator are merged into the outer Observable.</span>
+ *
+ * @example <caption>Count the number of click events</caption>
+ * const click$ = Rx.Observable.fromEvent(document, 'click');
+ * const one$ = click$.mapTo(1);
+ * const seed = 0;
+ * const count$ = one$.mergeScan((acc, one) => Rx.Observable.of(acc + one), seed);
+ * count$.subscribe(x => console.log(x));
+ *
+ * // Results:
+ * 1
+ * 2
+ * 3
+ * 4
+ * // ...and so on for each click
+ *
+ * @param {function(acc: R, value: T): Observable<R>} accumulator
+ * The accumulator function called on each source value.
+ * @param seed The initial accumulation value.
+ * @param {number} [concurrent=Number.POSITIVE_INFINITY] Maximum number of
+ * input Observables being subscribed to concurrently.
+ * @return {Observable<R>} An observable of the accumulated values.
+ * @method mergeScan
+ * @owner Observable
+ */
+export function mergeScan(accumulator, seed, concurrent = Number.POSITIVE_INFINITY) {
+    return (source) => source.lift(new MergeScanOperator(accumulator, seed, concurrent));
+}
+export class MergeScanOperator {
+    constructor(accumulator, seed, concurrent) {
+        this.accumulator = accumulator;
+        this.seed = seed;
+        this.concurrent = concurrent;
+    }
+    call(subscriber, source) {
+        return source.subscribe(new MergeScanSubscriber(subscriber, this.accumulator, this.seed, this.concurrent));
+    }
+}
+/**
+ * We need this JSDoc comment for affecting ESDoc.
+ * @ignore
+ * @extends {Ignored}
+ */
+export class MergeScanSubscriber extends OuterSubscriber {
+    constructor(destination, accumulator, acc, concurrent) {
+        super(destination);
+        this.accumulator = accumulator;
+        this.acc = acc;
+        this.concurrent = concurrent;
+        this.hasValue = false;
+        this.hasCompleted = false;
+        this.buffer = [];
+        this.active = 0;
+        this.index = 0;
+    }
+    _next(value) {
+        if (this.active < this.concurrent) {
+            const index = this.index++;
+            const ish = tryCatch(this.accumulator)(this.acc, value);
+            const destination = this.destination;
+            if (ish === errorObject) {
+                destination.error(errorObject.e);
+            }
+            else {
+                this.active++;
+                this._innerSub(ish, value, index);
+            }
+        }
+        else {
+            this.buffer.push(value);
+        }
+    }
+    _innerSub(ish, value, index) {
+        this.add(subscribeToResult(this, ish, value, index));
+    }
+    _complete() {
+        this.hasCompleted = true;
+        if (this.active === 0 && this.buffer.length === 0) {
+            if (this.hasValue === false) {
+                this.destination.next(this.acc);
+            }
+            this.destination.complete();
+        }
+    }
+    notifyNext(outerValue, innerValue, outerIndex, innerIndex, innerSub) {
+        const { destination } = this;
+        this.acc = innerValue;
+        this.hasValue = true;
+        destination.next(innerValue);
+    }
+    notifyComplete(innerSub) {
+        const buffer = this.buffer;
+        this.remove(innerSub);
+        this.active--;
+        if (buffer.length > 0) {
+            this._next(buffer.shift());
+        }
+        else if (this.active === 0 && this.hasCompleted) {
+            if (this.hasValue === false) {
+                this.destination.next(this.acc);
+            }
+            this.destination.complete();
+        }
+    }
+}
+//# sourceMappingURL=mergeScan.js.map