--- /dev/null
+import { Subject } from './Subject';
+import { SchedulerLike } from './types';
+import { queue } from './scheduler/queue';
+import { Subscriber } from './Subscriber';
+import { Subscription } from './Subscription';
+import { ObserveOnSubscriber } from './operators/observeOn';
+import { ObjectUnsubscribedError } from './util/ObjectUnsubscribedError';
+import { SubjectSubscription } from './SubjectSubscription';
+/**
+ * A variant of Subject that "replays" or emits old values to new subscribers.
+ * It buffers a set number of values and will emit those values immediately to
+ * any new subscribers in addition to emitting new values to existing subscribers.
+ *
+ * @class ReplaySubject<T>
+ */
+export class ReplaySubject<T> extends Subject<T> {
+ private _events: (ReplayEvent<T> | T)[] = [];
+ private _bufferSize: number;
+ private _windowTime: number;
+ private _infiniteTimeWindow: boolean = false;
+
+ constructor(bufferSize: number = Number.POSITIVE_INFINITY,
+ windowTime: number = Number.POSITIVE_INFINITY,
+ private scheduler?: SchedulerLike) {
+ super();
+ this._bufferSize = bufferSize < 1 ? 1 : bufferSize;
+ this._windowTime = windowTime < 1 ? 1 : windowTime;
+
+ if (windowTime === Number.POSITIVE_INFINITY) {
+ this._infiniteTimeWindow = true;
+ this.next = this.nextInfiniteTimeWindow;
+ } else {
+ this.next = this.nextTimeWindow;
+ }
+ }
+
+ private nextInfiniteTimeWindow(value: T): void {
+ const _events = this._events;
+ _events.push(value);
+ // Since this method is invoked in every next() call than the buffer
+ // can overgrow the max size only by one item
+ if (_events.length > this._bufferSize) {
+ _events.shift();
+ }
+
+ super.next(value);
+ }
+
+ private nextTimeWindow(value: T): void {
+ this._events.push(new ReplayEvent(this._getNow(), value));
+ this._trimBufferThenGetEvents();
+
+ super.next(value);
+ }
+
+ /** @deprecated This is an internal implementation detail, do not use. */
+ _subscribe(subscriber: Subscriber<T>): Subscription {
+ // When `_infiniteTimeWindow === true` then the buffer is already trimmed
+ const _infiniteTimeWindow = this._infiniteTimeWindow;
+ const _events = _infiniteTimeWindow ? this._events : this._trimBufferThenGetEvents();
+ const scheduler = this.scheduler;
+ const len = _events.length;
+ let subscription: Subscription;
+
+ if (this.closed) {
+ throw new ObjectUnsubscribedError();
+ } else if (this.isStopped || this.hasError) {
+ subscription = Subscription.EMPTY;
+ } else {
+ this.observers.push(subscriber);
+ subscription = new SubjectSubscription(this, subscriber);
+ }
+
+ if (scheduler) {
+ subscriber.add(subscriber = new ObserveOnSubscriber<T>(subscriber, scheduler));
+ }
+
+ if (_infiniteTimeWindow) {
+ for (let i = 0; i < len && !subscriber.closed; i++) {
+ subscriber.next(<T>_events[i]);
+ }
+ } else {
+ for (let i = 0; i < len && !subscriber.closed; i++) {
+ subscriber.next((<ReplayEvent<T>>_events[i]).value);
+ }
+ }
+
+ if (this.hasError) {
+ subscriber.error(this.thrownError);
+ } else if (this.isStopped) {
+ subscriber.complete();
+ }
+
+ return subscription;
+ }
+
+ _getNow(): number {
+ return (this.scheduler || queue).now();
+ }
+
+ private _trimBufferThenGetEvents(): ReplayEvent<T>[] {
+ const now = this._getNow();
+ const _bufferSize = this._bufferSize;
+ const _windowTime = this._windowTime;
+ const _events = <ReplayEvent<T>[]>this._events;
+
+ const eventsCount = _events.length;
+ let spliceCount = 0;
+
+ // Trim events that fall out of the time window.
+ // Start at the front of the list. Break early once
+ // we encounter an event that falls within the window.
+ while (spliceCount < eventsCount) {
+ if ((now - _events[spliceCount].time) < _windowTime) {
+ break;
+ }
+ spliceCount++;
+ }
+
+ if (eventsCount > _bufferSize) {
+ spliceCount = Math.max(spliceCount, eventsCount - _bufferSize);
+ }
+
+ if (spliceCount > 0) {
+ _events.splice(0, spliceCount);
+ }
+
+ return _events;
+ }
+
+}
+
+class ReplayEvent<T> {
+ constructor(public time: number, public value: T) {
+ }
+}