import { Operator } from '../Operator';
import { Subscriber } from '../Subscriber';
import { IScheduler } from '../Scheduler';
import { Subscription, TeardownLogic } from '../Subscription';
import { async } from '../scheduler/async';
import { Observable } from '../Observable';
import { ThrottleConfig, defaultThrottleConfig } from './throttle';
import { MonoTypeOperatorFunction } from '../interfaces';
/**
* Emits a value from the source Observable, then ignores subsequent source
* values for `duration` milliseconds, then repeats this process.
*
* Lets a value pass, then ignores source values for the
* next `duration` milliseconds.
*
*
*
* `throttleTime` emits the source Observable values on the output Observable
* when its internal timer is disabled, and ignores source values when the timer
* is enabled. Initially, the timer is disabled. As soon as the first source
* value arrives, it is forwarded to the output Observable, and then the timer
* is enabled. After `duration` milliseconds (or the time unit determined
* internally by the optional `scheduler`) has passed, the timer is disabled,
* and this process repeats for the next source value. Optionally takes a
* {@link IScheduler} for managing timers.
*
* @example
Emit clicks at a rate of at most one click per second
* var clicks = Rx.Observable.fromEvent(document, 'click');
* var result = clicks.throttleTime(1000);
* result.subscribe(x => console.log(x));
*
* @see {@link auditTime}
* @see {@link debounceTime}
* @see {@link delay}
* @see {@link sampleTime}
* @see {@link throttle}
*
* @param {number} duration Time to wait before emitting another value after
* emitting the last value, measured in milliseconds or the time unit determined
* internally by the optional `scheduler`.
* @param {Scheduler} [scheduler=async] The {@link IScheduler} to use for
* managing the timers that handle the throttling.
* @return {Observable} An Observable that performs the throttle operation to
* limit the rate of emissions from the source.
* @method throttleTime
* @owner Observable
*/
export function throttleTime(duration: number,
scheduler: IScheduler = async,
config: ThrottleConfig = defaultThrottleConfig): MonoTypeOperatorFunction {
return (source: Observable) => source.lift(new ThrottleTimeOperator(duration, scheduler, config.leading, config.trailing));
}
class ThrottleTimeOperator implements Operator {
constructor(private duration: number,
private scheduler: IScheduler,
private leading: boolean,
private trailing: boolean) {
}
call(subscriber: Subscriber, source: any): TeardownLogic {
return source.subscribe(
new ThrottleTimeSubscriber(subscriber, this.duration, this.scheduler, this.leading, this.trailing)
);
}
}
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
class ThrottleTimeSubscriber extends Subscriber {
private throttled: Subscription;
private _hasTrailingValue: boolean = false;
private _trailingValue: T = null;
constructor(destination: Subscriber,
private duration: number,
private scheduler: IScheduler,
private leading: boolean,
private trailing: boolean) {
super(destination);
}
protected _next(value: T) {
if (this.throttled) {
if (this.trailing) {
this._trailingValue = value;
this._hasTrailingValue = true;
}
} else {
this.add(this.throttled = this.scheduler.schedule(dispatchNext, this.duration, { subscriber: this }));
if (this.leading) {
this.destination.next(value);
}
}
}
clearThrottle() {
const throttled = this.throttled;
if (throttled) {
if (this.trailing && this._hasTrailingValue) {
this.destination.next(this._trailingValue);
this._trailingValue = null;
this._hasTrailingValue = false;
}
throttled.unsubscribe();
this.remove(throttled);
this.throttled = null;
}
}
}
interface DispatchArg {
subscriber: ThrottleTimeSubscriber;
}
function dispatchNext(arg: DispatchArg) {
const { subscriber } = arg;
subscriber.clearThrottle();
}