dependencies.yml

dependencies:
  com.thesamet.scalapb:
    scalapb-runtime:
      lang: scala
      version: '0.10.0-M1'

ProtobufBytesBijection.scala

// Consider pulling in Algebird. See full implementation:
// https://github.com/twitter/bijection/blob/0.8.0/bijection-core/src/main/scala/com/twitter/bijection/Bijection.scala
@implicitNotFound(msg = "Could not find a BytesBijection for ${T}")
trait Bijection[A, B] extends (A => B) {
  def invert(b: B): A

  def andThen[C](g: Bijection[B, C]): Bijection[A, C] = {
    val self = this
    new Bijection[A, C] {
      override def apply(a: A) = g(self.apply(a))
      override def invert(c: C) = self.invert(g.invert(c))
    }
  }
}

object ProtobufBytesBijection {
  import scalapb._

  type MessageDef[T] = GeneratedMessage with Message[T]
  type CompanionDef[T <: MessageDef[T]] = GeneratedMessageCompanion[T]

  implicit def apply[T <: MessageDef[T]: CompanionDef]: Bijection[T, Array[Byte]] = {
    new Bijection[T, Array[Byte]] {
      override def apply(t: T) = t.toByteArray
      override def invert(buf: Array[Byte]) = implicitly[CompanionDef[T]].parseFrom(buf)
    }
  }
}