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package.scala
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package.scala
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/*
* Copyright 2017 47 Degrees, LLC. <http://www.47deg.com>
*
* 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 freestyle.cassandra
import java.nio.ByteBuffer
import freestyle.cassandra.codecs.ByteBufferCodec
import shapeless._
import shapeless.labelled.FieldType
package object mapper {
type MappedField = (String, ByteBuffer)
trait FieldMapper[A] {
def map(a: A): List[MappedField]
}
trait FieldMapperPrimitive {
def createFieldMapper[A](f: A => List[MappedField]): FieldMapper[A] =
new FieldMapper[A] {
override def map(a: A): List[MappedField] = f(a)
}
implicit def primitiveFieldMapper[K <: Symbol, H, T <: HList](
implicit witness: Witness.Aux[K],
codec: Lazy[ByteBufferCodec[H]],
tMapper: FieldMapper[T]): FieldMapper[FieldType[K, H] :: T] = {
val fieldName = witness.value.name
createFieldMapper { hlist =>
(fieldName -> codec.value.serialize(hlist.head)) :: tMapper.map(hlist.tail)
}
}
}
trait FieldMapperGeneric extends FieldMapperPrimitive {
implicit def genericMapper[A, R](
implicit gen: LabelledGeneric.Aux[A, R],
mapper: Lazy[FieldMapper[R]]): FieldMapper[A] =
createFieldMapper(value => mapper.value.map(gen.to(value)))
implicit val hnilMapper: FieldMapper[HNil] = new FieldMapper[HNil] {
override def map(a: HNil): List[MappedField] = Nil
}
}
object FieldMapper extends FieldMapperGeneric
object FieldMapperExpanded extends FieldMapperGeneric {
implicit def hconsMapper[K, H, T <: HList](
implicit hMapper: Lazy[FieldMapper[H]],
tMapper: FieldMapper[T]): FieldMapper[FieldType[K, H] :: T] =
createFieldMapper { hlist =>
hMapper.value.map(hlist.head) ++ tMapper.map(hlist.tail)
}
}
}