some spray RequestTransformer example with Lenses

TwitterActor.scala

trait SprayContribForRequestTransformer {

  object HttpRequestBuilderLens {
    val queryLens = new Lens[Uri, Query] {
      def get(c: Uri): Query = c.query

      def set(c: Uri)(f: Query): Uri = c.copy(query = f)
    }

    val uriLens = new Lens[HttpRequest, Uri] {
      def get(c: HttpRequest): Uri = c.uri

      def set(c: HttpRequest)(f: Uri): HttpRequest = c.copy(uri = f)
    }

    val headersLens = new Lens[HttpRequest, List[HttpHeader]] {
      def get(c: HttpRequest): List[HttpHeader] = c.headers

      def set(c: HttpRequest)(f: List[HttpHeader]): HttpRequest = c.withHeaders(f)
    }

    def byLowercaseNameF(lowercaseName:String): HttpHeader => Boolean = _.isNot(lowercaseName)

    val queryFromHttpRequestLens = queryLens.compose(uriLens)

    def singleHeaderByNameLens(lowercaseName: String) = new Lens[List[HttpHeader], Option[HttpHeader]] {

      val byLowercaseName = byLowercaseNameF(lowercaseName)

      def get(c: List[HttpHeader]): Option[HttpHeader] = c.find(byLowercaseName)

      def set(c: List[HttpHeader])(f: Option[HttpHeader]): List[HttpHeader] = f match {
        case None => c.filterNot(byLowercaseName)
        case Some(h) => c :+ h
      }
    }

    def singleHeaderByNameFromHttpRequestLens(lowercaseName: String) = singleHeaderByNameLens(lowercaseName).compose(headersLens)
  }

  object HttpTransformerContrib {
    type HeadersTransformer = List[HttpHeader]=>List[HttpHeader]
    import HttpRequestBuilderLens._

    def withQuery(q:Query):RequestTransformer = queryFromHttpRequestLens.set(_)(q)

    def withQueryTransformer(f:Query=>Query):RequestTransformer = queryFromHttpRequestLens.modify(_)(f)

    def withQueryParameter(kv:(String,String)):RequestTransformer =  queryFromHttpRequestLens.modify(_)(kv +: _)

    def withSingleValueHeader(h:HttpHeader):RequestTransformer = singleHeaderByNameFromHttpRequestLens(h.lowercaseName).set(_)(Some(h))

    def withHeaderTransformer(f:HeadersTransformer) :RequestTransformer = headersLens.modify(_)(f)

    def withoutHeader(lowercaseName:String):RequestTransformer = headersLens.modify(_)(_.filter(byLowercaseNameF(lowercaseName)))
}

  


}