{"ast":null,"code":"import { Subscriber } from '../Subscriber';\nexport function pairwise() {\n  return source => source.lift(new PairwiseOperator());\n}\n\nclass PairwiseOperator {\n  call(subscriber, source) {\n    return source.subscribe(new PairwiseSubscriber(subscriber));\n  }\n\n}\n\nclass PairwiseSubscriber extends Subscriber {\n  constructor(destination) {\n    super(destination);\n    this.hasPrev = false;\n  }\n\n  _next(value) {\n    let pair;\n\n    if (this.hasPrev) {\n      pair = [this.prev, value];\n    } else {\n      this.hasPrev = true;\n    }\n\n    this.prev = value;\n\n    if (pair) {\n      this.destination.next(pair);\n    }\n  }\n\n} //# sourceMappingURL=pairwise.js.map","map":null,"metadata":{},"sourceType":"module"}