feat(bufferTime): add higher-order lettable version of bufferTime operator

Author: benlesh

src/operator/bufferTime.ts

@@ -1,11 +1,8 @@
 import { IScheduler } from '../Scheduler';
-import { Action } from '../scheduler/Action';
-import { Operator } from '../Operator';
 import { async } from '../scheduler/async';
 import { Observable } from '../Observable';
-import { Subscriber } from '../Subscriber';
-import { Subscription } from '../Subscription';
 import { isScheduler } from '../util/isScheduler';
+import { bufferTime as higherOrder } from '../operators';
 
 /* tslint:disable:max-line-length */
 export function bufferTime<T>(this: Observable<T>, bufferTimeSpan: number, scheduler?: IScheduler): Observable<T[]>;
@@ -75,160 +72,5 @@ export function bufferTime<T>(this: Observable<T>, bufferTimeSpan: number): Obse
     maxBufferSize = arguments[2];
   }
 
-  return this.lift(new BufferTimeOperator<T>(bufferTimeSpan, bufferCreationInterval, maxBufferSize, scheduler));
-}
-
-class BufferTimeOperator<T> implements Operator<T, T[]> {
-  constructor(private bufferTimeSpan: number,
-              private bufferCreationInterval: number,
-              private maxBufferSize: number,
-              private scheduler: IScheduler) {
-  }
-
-  call(subscriber: Subscriber<T[]>, source: any): any {
-    return source.subscribe(new BufferTimeSubscriber(
-      subscriber, this.bufferTimeSpan, this.bufferCreationInterval, this.maxBufferSize, this.scheduler
-    ));
-  }
-}
-
-class Context<T> {
-  buffer: T[] = [];
-  closeAction: Subscription;
-}
-
-type CreationState<T> = {
-  bufferTimeSpan: number;
-  bufferCreationInterval: number,
-  subscriber: BufferTimeSubscriber<T>;
-  scheduler: IScheduler;
-};
-
-/**
- * We need this JSDoc comment for affecting ESDoc.
- * @ignore
- * @extends {Ignored}
- */
-class BufferTimeSubscriber<T> extends Subscriber<T> {
-  private contexts: Array<Context<T>> = [];
-  private timespanOnly: boolean;
-
-  constructor(destination: Subscriber<T[]>,
-              private bufferTimeSpan: number,
-              private bufferCreationInterval: number,
-              private maxBufferSize: number,
-              private scheduler: IScheduler) {
-    super(destination);
-    const context = this.openContext();
-    this.timespanOnly = bufferCreationInterval == null || bufferCreationInterval < 0;
-    if (this.timespanOnly) {
-      const timeSpanOnlyState = { subscriber: this, context, bufferTimeSpan };
-      this.add(context.closeAction = scheduler.schedule(dispatchBufferTimeSpanOnly, bufferTimeSpan, timeSpanOnlyState));
-    } else {
-      const closeState = { subscriber: this, context };
-      const creationState: CreationState<T> = { bufferTimeSpan, bufferCreationInterval, subscriber: this, scheduler };
-      this.add(context.closeAction = scheduler.schedule(dispatchBufferClose, bufferTimeSpan, closeState));
-      this.add(scheduler.schedule(dispatchBufferCreation, bufferCreationInterval, creationState));
-    }
-  }
-
-  protected _next(value: T) {
-    const contexts = this.contexts;
-    const len = contexts.length;
-    let filledBufferContext: Context<T>;
-    for (let i = 0; i < len; i++) {
-      const context = contexts[i];
-      const buffer = context.buffer;
-      buffer.push(value);
-      if (buffer.length == this.maxBufferSize) {
-        filledBufferContext = context;
-      }
-    }
-
-    if (filledBufferContext) {
-      this.onBufferFull(filledBufferContext);
-    }
-  }
-
-  protected _error(err: any) {
-    this.contexts.length = 0;
-    super._error(err);
-  }
-
-  protected _complete() {
-    const { contexts, destination } = this;
-    while (contexts.length > 0) {
-      const context = contexts.shift();
-      destination.next(context.buffer);
-    }
-    super._complete();
-  }
-
-  protected _unsubscribe() {
-    this.contexts = null;
-  }
-
-  protected onBufferFull(context: Context<T>) {
-    this.closeContext(context);
-    const closeAction = context.closeAction;
-    closeAction.unsubscribe();
-    this.remove(closeAction);
-
-    if (!this.closed && this.timespanOnly) {
-      context = this.openContext();
-      const bufferTimeSpan = this.bufferTimeSpan;
-      const timeSpanOnlyState = { subscriber: this, context, bufferTimeSpan };
-      this.add(context.closeAction = this.scheduler.schedule(dispatchBufferTimeSpanOnly, bufferTimeSpan, timeSpanOnlyState));
-    }
-  }
-
-  openContext(): Context<T> {
-    const context: Context<T> = new Context<T>();
-    this.contexts.push(context);
-    return context;
-  }
-
-  closeContext(context: Context<T>) {
-    this.destination.next(context.buffer);
-    const contexts = this.contexts;
-
-    const spliceIndex = contexts ? contexts.indexOf(context) : -1;
-    if (spliceIndex >= 0) {
-      contexts.splice(contexts.indexOf(context), 1);
-    }
-  }
-}
-
-function dispatchBufferTimeSpanOnly(this: Action<any>, state: any) {
-  const subscriber: BufferTimeSubscriber<any> = state.subscriber;
-
-  const prevContext = state.context;
-  if (prevContext) {
-    subscriber.closeContext(prevContext);
-  }
-
-  if (!subscriber.closed) {
-    state.context = subscriber.openContext();
-    state.context.closeAction = this.schedule(state, state.bufferTimeSpan);
-  }
-}
-
-interface DispatchArg<T> {
-  subscriber: BufferTimeSubscriber<T>;
-  context: Context<T>;
-}
-
-function dispatchBufferCreation<T>(this: Action<CreationState<T>>, state: CreationState<T>) {
-  const { bufferCreationInterval, bufferTimeSpan, subscriber, scheduler } = state;
-  const context = subscriber.openContext();
-  const action = <Action<CreationState<T>>>this;
-  if (!subscriber.closed) {
-    subscriber.add(context.closeAction = scheduler.schedule<DispatchArg<T>>(dispatchBufferClose, bufferTimeSpan, { subscriber, context }));
-    action.schedule(state, bufferCreationInterval);
-  }
-}
-
-function dispatchBufferClose<T>(arg: DispatchArg<T>) {
-  const { subscriber, context } = arg;
-  subscriber.closeContext(context);
+  return higherOrder(bufferTimeSpan, bufferCreationInterval, maxBufferSize, scheduler)(this);
 }