spray.routing.Prepender.scala Maven / Gradle / Ivy
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A suite of lightweight Scala libraries for building and consuming RESTful web services on top of Akka
/*
* Copyright © 2011-2013 the spray project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package spray.routing
import shapeless._
// TODO: check whether we can remove this additional layer on top of PrependAux
trait Prepender[P <: HList, S <: HList] {
type Out <: HList
def apply(prefix: P, suffix: S): Out
}
object Prepender {
implicit def hnilPrepend[P <: HList, S <: HNil] = new Prepender[P, S] {
type Out = P
def apply(prefix: P, suffix: S) = prefix
}
implicit def apply[P <: HList, S <: HList, Out0 <: HList](implicit prepend: PrependAux[P, S, Out0]) =
new Prepender[P, S] {
type Out = Out0
def apply(prefix: P, suffix: S): Out = prepend(prefix, suffix)
}
}