| import { Subscriber } from '../Subscriber'; | 
| export function pairwise() { | 
|     return (source) => source.lift(new PairwiseOperator()); | 
| } | 
| class PairwiseOperator { | 
|     call(subscriber, source) { | 
|         return source.subscribe(new PairwiseSubscriber(subscriber)); | 
|     } | 
| } | 
| class PairwiseSubscriber extends Subscriber { | 
|     constructor(destination) { | 
|         super(destination); | 
|         this.hasPrev = false; | 
|     } | 
|     _next(value) { | 
|         let pair; | 
|         if (this.hasPrev) { | 
|             pair = [this.prev, value]; | 
|         } | 
|         else { | 
|             this.hasPrev = true; | 
|         } | 
|         this.prev = value; | 
|         if (pair) { | 
|             this.destination.next(pair); | 
|         } | 
|     } | 
| } | 
| //# sourceMappingURL=pairwise.js.map |