io.circe.generic.extras.encoding.EnumerationEncoder.scala Maven / Gradle / Ivy
package io.circe.generic.extras.encoding
import io.circe.{ Encoder, Json }
import shapeless.{ :+:, CNil, Coproduct, HNil, Inl, Inr, LabelledGeneric, Witness }
import shapeless.labelled.FieldType
abstract class EnumerationEncoder[A] extends Encoder[A]
final object EnumerationEncoder {
implicit val encodeEnumerationCNil: EnumerationEncoder[CNil] = new EnumerationEncoder[CNil] {
def apply(a: CNil): Json = sys.error("Cannot encode CNil")
}
implicit def encodeEnumerationCCons[K <: Symbol, V, R <: Coproduct](
implicit
wit: Witness.Aux[K],
gv: LabelledGeneric.Aux[V, HNil],
dr: EnumerationEncoder[R]
): EnumerationEncoder[FieldType[K, V] :+: R] = new EnumerationEncoder[FieldType[K, V] :+: R] {
def apply(a: FieldType[K, V] :+: R): Json = a match {
case Inl(l) => Json.fromString(wit.value.name)
case Inr(r) => dr(r)
}
}
implicit def encodeEnumeration[A, Repr <: Coproduct](
implicit
gen: LabelledGeneric.Aux[A, Repr],
rr: EnumerationEncoder[Repr]
): EnumerationEncoder[A] =
new EnumerationEncoder[A] {
def apply(a: A): Json = rr(gen.to(a))
}
}