io.circe.generic.extras.decoding.ReprDecoder.scala Maven / Gradle / Ivy
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package io.circe.generic.extras.decoding
import cats.data.Validated
import io.circe.{ ACursor, Decoder, HCursor }
import io.circe.Json.JNull
import io.circe.generic.extras.ConfigurableDeriver
import scala.collection.immutable.Map
import scala.language.experimental.macros
import shapeless.HNil
/**
* A decoder for a generic representation of a case class or ADT.
*
* Note that users typically will not work with instances of this class, which
* contains unsafe methods (specifically the two `configuredDecode` methods,
* which allow passing in an untyped map of default field values).
*/
abstract class ReprDecoder[A] extends Decoder[A] {
def configuredDecode(c: HCursor)(
transformMemberNames: String => String,
transformConstructorNames: String => String,
defaults: Map[String, Any],
discriminator: Option[String]
): Decoder.Result[A]
def configuredDecodeAccumulating(c: HCursor)(
transformMemberNames: String => String,
transformConstructorNames: String => String,
defaults: Map[String, Any],
discriminator: Option[String]
): Decoder.AccumulatingResult[A]
final protected[this] def orDefault[B](
c: ACursor,
decoder: Decoder[B],
name: String,
defaults: Map[String, Any]
): Decoder.Result[B] = {
decoder.tryDecode(c) match {
case r @ Right(_) if r ne Decoder.keyMissingNone => r
case l @ Left(_) if c.succeeded && !c.focus.contains(JNull) => l
case r =>
defaults.get(name) match {
case Some(d: B @unchecked) => Right(d)
case _ => r
}
}
}
final protected[this] def orDefaultAccumulating[B](
c: ACursor,
decoder: Decoder[B],
name: String,
defaults: Map[String, Any]
): Decoder.AccumulatingResult[B] = {
decoder.tryDecodeAccumulating(c) match {
case r @ Validated.Valid(_) if r ne Decoder.keyMissingNoneAccumulating => r
case l @ Validated.Invalid(_) if c.succeeded && !c.focus.contains(JNull) => l
case r =>
defaults.get(name) match {
case Some(d: B @unchecked) => Validated.valid(d)
case _ => r
}
}
}
final protected[this] def withDiscriminator[V](
decode: Decoder[V],
c: HCursor,
name: String,
discriminator: Option[String]
): Option[Decoder.Result[V]] = discriminator match {
case None =>
val result = c.downField(name)
if (result.succeeded) Some(decode.tryDecode(result)) else None
case Some(disc) =>
c.get[String](disc) match {
case Right(leafType) if leafType == name => Some(decode(c))
case Right(_) => None
case l @ Left(_) => Some(l.asInstanceOf[Decoder.Result[V]])
}
}
final protected[this] def withDiscriminatorAccumulating[V](
decode: Decoder[V],
c: HCursor,
name: String,
discriminator: Option[String]
): Option[Decoder.AccumulatingResult[V]] = discriminator match {
case None =>
val result = c.downField(name)
if (result.succeeded) Some(decode.tryDecodeAccumulating(result)) else None
case Some(disc) =>
c.get[String](disc) match {
case Right(leafType) if leafType == name =>
Some(decode.tryDecodeAccumulating(c))
case Right(_) => None
case Left(err) => Some(Validated.invalidNel(err))
}
}
final def apply(c: HCursor): Decoder.Result[A] =
configuredDecode(c)(Predef.identity, Predef.identity, Map.empty, None)
final override def decodeAccumulating(c: HCursor): Decoder.AccumulatingResult[A] =
configuredDecodeAccumulating(c)(Predef.identity, Predef.identity, Map.empty, None)
}
final object ReprDecoder {
implicit def deriveReprDecoder[R]: ReprDecoder[R] = macro ConfigurableDeriver.deriveDecoder[R]
val hnilReprDecoder: ReprDecoder[HNil] = new ReprDecoder[HNil] {
def configuredDecode(c: HCursor)(
transformMemberNames: String => String,
transformConstructorNames: String => String,
defaults: Map[String, Any],
discriminator: Option[String]
): Decoder.Result[HNil] = Right(HNil)
def configuredDecodeAccumulating(c: HCursor)(
transformMemberNames: String => String,
transformConstructorNames: String => String,
defaults: Map[String, Any],
discriminator: Option[String]
): Decoder.AccumulatingResult[HNil] = Validated.valid(HNil)
}
}