Fix EsLint Brackets (error markup 'const').

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

@@ -0,0 +1,79 @@
+import { Observable } from '../Observable';
+import { scan } from './scan';
+import { takeLast } from './takeLast';
+import { defaultIfEmpty } from './defaultIfEmpty';
+import { OperatorFunction, MonoTypeOperatorFunction } from '../types';
+import { pipe } from '../util/pipe';
+
+/* tslint:disable:max-line-length */
+export function reduce<T>(accumulator: (acc: T, value: T, index: number) => T, seed?: T): MonoTypeOperatorFunction<T>;
+export function reduce<T>(accumulator: (acc: T[], value: T, index: number) => T[], seed: T[]): OperatorFunction<T, T[]>;
+export function reduce<T, R>(accumulator: (acc: R, value: T, index: number) => R, seed?: R): OperatorFunction<T, R>;
+/* tslint:enable:max-line-length */
+
+/**
+ * Applies an accumulator function over the source Observable, and returns the
+ * accumulated result when the source completes, given an optional seed value.
+ *
+ * <span class="informal">Combines together all values emitted on the source,
+ * using an accumulator function that knows how to join a new source value into
+ * the accumulation from the past.</span>
+ *
+ * ![](reduce.png)
+ *
+ * Like
+ * [Array.prototype.reduce()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce),
+ * `reduce` applies an `accumulator` function against an accumulation and each
+ * value of the source Observable (from the past) to reduce it to a single
+ * value, emitted on the output Observable. Note that `reduce` will only emit
+ * one value, only when the source Observable completes. It is equivalent to
+ * applying operator {@link scan} followed by operator {@link last}.
+ *
+ * Returns an Observable that applies a specified `accumulator` function to each
+ * item emitted by the source Observable. If a `seed` value is specified, then
+ * that value will be used as the initial value for the accumulator. If no seed
+ * value is specified, the first item of the source is used as the seed.
+ *
+ * ## Example
+ * Count the number of click events that happened in 5 seconds
+ * ```javascript
+ * const clicksInFiveSeconds = fromEvent(document, 'click').pipe(
+ *   takeUntil(interval(5000)),
+ * );
+ * const ones = clicksInFiveSeconds.pipe(mapTo(1));
+ * const seed = 0;
+ * const count = ones.reduce((acc, one) => acc + one, seed);
+ * count.subscribe(x => console.log(x));
+ * ```
+ *
+ * @see {@link count}
+ * @see {@link expand}
+ * @see {@link mergeScan}
+ * @see {@link scan}
+ *
+ * @param {function(acc: R, value: T, index: number): R} accumulator The accumulator function
+ * called on each source value.
+ * @param {R} [seed] The initial accumulation value.
+ * @return {Observable<R>} An Observable that emits a single value that is the
+ * result of accumulating the values emitted by the source Observable.
+ * @method reduce
+ * @owner Observable
+ */
+export function reduce<T, R>(accumulator: (acc: R, value: T, index?: number) => R, seed?: R): OperatorFunction<T, R> {
+  // providing a seed of `undefined` *should* be valid and trigger
+  // hasSeed! so don't use `seed !== undefined` checks!
+  // For this reason, we have to check it here at the original call site
+  // otherwise inside Operator/Subscriber we won't know if `undefined`
+  // means they didn't provide anything or if they literally provided `undefined`
+  if (arguments.length >= 2) {
+    return function reduceOperatorFunctionWithSeed(source: Observable<T>): Observable<R> {
+      return pipe(scan(accumulator, seed), takeLast(1), defaultIfEmpty(seed))(source);
+    };
+  }
+  return function reduceOperatorFunction(source: Observable<T>): Observable<R> {
+    return pipe(
+      scan((acc: R, value: T, index: number): R => accumulator(acc, value, index + 1)),
+      takeLast(1),
+    )(source);
+  };
+}