routie dev init since i didn't adhere to any proper guidance up until now

frontend/node_modules/rxjs/src/internal/operators/connect.ts

@@ -0,0 +1,109 @@
+import { OperatorFunction, ObservableInput, ObservedValueOf, SubjectLike } from '../types';
+import { Observable } from '../Observable';
+import { Subject } from '../Subject';
+import { innerFrom } from '../observable/innerFrom';
+import { operate } from '../util/lift';
+import { fromSubscribable } from '../observable/fromSubscribable';
+
+/**
+ * An object used to configure {@link connect} operator.
+ */
+export interface ConnectConfig<T> {
+  /**
+   * A factory function used to create the Subject through which the source
+   * is multicast. By default, this creates a {@link Subject}.
+   */
+  connector: () => SubjectLike<T>;
+}
+
+/**
+ * The default configuration for `connect`.
+ */
+const DEFAULT_CONFIG: ConnectConfig<unknown> = {
+  connector: () => new Subject<unknown>(),
+};
+
+/**
+ * Creates an observable by multicasting the source within a function that
+ * allows the developer to define the usage of the multicast prior to connection.
+ *
+ * This is particularly useful if the observable source you wish to multicast could
+ * be synchronous or asynchronous. This sets it apart from {@link share}, which, in the
+ * case of totally synchronous sources will fail to share a single subscription with
+ * multiple consumers, as by the time the subscription to the result of {@link share}
+ * has returned, if the source is synchronous its internal reference count will jump from
+ * 0 to 1 back to 0 and reset.
+ *
+ * To use `connect`, you provide a `selector` function that will give you
+ * a multicast observable that is not yet connected. You then use that multicast observable
+ * to create a resulting observable that, when subscribed, will set up your multicast. This is
+ * generally, but not always, accomplished with {@link merge}.
+ *
+ * Note that using a {@link takeUntil} inside of `connect`'s `selector` _might_ mean you were looking
+ * to use the {@link takeWhile} operator instead.
+ *
+ * When you subscribe to the result of `connect`, the `selector` function will be called. After
+ * the `selector` function returns, the observable it returns will be subscribed to, _then_ the
+ * multicast will be connected to the source.
+ *
+ * ## Example
+ *
+ * Sharing a totally synchronous observable
+ *
+ * ```ts
+ * import { of, tap, connect, merge, map, filter } from 'rxjs';
+ *
+ * const source$ = of(1, 2, 3, 4, 5).pipe(
+ *   tap({
+ *     subscribe: () => console.log('subscription started'),
+ *     next: n => console.log(`source emitted ${ n }`)
+ *   })
+ * );
+ *
+ * source$.pipe(
+ *   // Notice in here we're merging 3 subscriptions to `shared$`.
+ *   connect(shared$ => merge(
+ *     shared$.pipe(map(n => `all ${ n }`)),
+ *     shared$.pipe(filter(n => n % 2 === 0), map(n => `even ${ n }`)),
+ *     shared$.pipe(filter(n => n % 2 === 1), map(n => `odd ${ n }`))
+ *   ))
+ * )
+ * .subscribe(console.log);
+ *
+ * // Expected output: (notice only one subscription)
+ * 'subscription started'
+ * 'source emitted 1'
+ * 'all 1'
+ * 'odd 1'
+ * 'source emitted 2'
+ * 'all 2'
+ * 'even 2'
+ * 'source emitted 3'
+ * 'all 3'
+ * 'odd 3'
+ * 'source emitted 4'
+ * 'all 4'
+ * 'even 4'
+ * 'source emitted 5'
+ * 'all 5'
+ * 'odd 5'
+ * ```
+ *
+ * @param selector A function used to set up the multicast. Gives you a multicast observable
+ * that is not yet connected. With that, you're expected to create and return
+ * and Observable, that when subscribed to, will utilize the multicast observable.
+ * After this function is executed -- and its return value subscribed to -- the
+ * operator will subscribe to the source, and the connection will be made.
+ * @param config The configuration object for `connect`.
+ */
+export function connect<T, O extends ObservableInput<unknown>>(
+  selector: (shared: Observable<T>) => O,
+  config: ConnectConfig<T> = DEFAULT_CONFIG
+): OperatorFunction<T, ObservedValueOf<O>> {
+  const { connector } = config;
+  return operate((source, subscriber) => {
+    const subject = connector();
+    innerFrom(selector(fromSubscribable(subject))).subscribe(subscriber);
+    subscriber.add(source.subscribe(subject));
+  });
+}