Add UnaryDeserializer Either derivation support (#13)

azavea · Apr 10, 2022 · 9f5c82d · 9f5c82d
1 parent 7a66401
commit 9f5c82d
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Showing 3 changed files with 17 additions and 2 deletions.
diff --git a/core/src/main/scala/com/azavea/hiveless/serializers/UnaryDeserializer.scala b/core/src/main/scala/com/azavea/hiveless/serializers/UnaryDeserializer.scala
@@ -27,6 +27,7 @@ import cats.Id
 import cats.syntax.apply._
 import org.apache.spark.sql.catalyst.encoders.ExpressionEncoder
 import org.apache.spark.sql.catalyst.util.ArrayData
+import shapeless.ops.coproduct.{CoproductToEither, EitherToCoproduct}
 import shapeless.{:+:, CNil, Coproduct, HNil, Inl, Inr, IsTuple}
 
 import scala.reflect.ClassTag
@@ -175,8 +176,15 @@ object UnaryDeserializer extends Serializable {
       Try(arrayDataUnaryDeserializer.deserialize(arguments, inspectors).toArray[T](HSerializer[T].dataType))
         .getOrElse(nativeArrayUnaryDeserializer.deserialize(arguments, inspectors))
 
-  /** Coproduct deserializer. */
-  implicit def unaryDeserializerCCons[H, T <: Coproduct](implicit
+  /** Coproduct deserializers. */
+  implicit def eitherUnaryDeserializer[L, R, P <: Coproduct](implicit
+    etp: EitherToCoproduct.Aux[L, R, P],
+    dp: UnaryDeserializer[Id, P],
+    pte: CoproductToEither.Aux[P, Either[L, R]]
+  ): UnaryDeserializer[Id, Either[L, R]] =
+    (arguments, inspectors) => pte(dp.deserialize(arguments, inspectors))
+
+  implicit def cconsUnaryDeserializer[H, T <: Coproduct](implicit
     dh: UnaryDeserializer[Id, H],
     dt: UnaryDeserializer[Id, T]
   ): UnaryDeserializer[Id, H :+: T] =

diff --git a/core/src/main/scala/com/azavea/hiveless/utils/HShow.scala b/core/src/main/scala/com/azavea/hiveless/utils/HShow.scala
@@ -16,6 +16,7 @@
 
 package com.azavea.hiveless.utils
 
+import shapeless.ops.coproduct.EitherToCoproduct
 import shapeless.{:+:, ::, CNil, Coproduct, Generic, HList, HNil, IsTuple}
 
 import scala.reflect.{classTag, ClassTag}
@@ -32,6 +33,10 @@ object HShow extends LowPriorityHShow {
   implicit def hshowGeneric[T: IsTuple, L <: HList](implicit gen: Generic.Aux[T, L], sl: HShow[L]): HShow[T] =
     () => sl.show()
 
+  /** Derive HShow for Either. */
+  implicit def hshowEither[L, R, P <: Coproduct](implicit etp: EitherToCoproduct.Aux[L, R, P], sp: HShow[P]): HShow[Either[L, R]] =
+    () => sp.show()
+
   /** Derive HShow for HList. */
   implicit val hshowHNil: HShow[HNil] = () => ""
   implicit def hshowHCons[H: ClassTag, T <: HList](implicit sh: HShow[H], st: HShow[T]): HShow[H :: T] = () => {

diff --git a/spatial-index/src/main/scala/com/azavea/hiveless/spatial/index/ST_Intersects.scala b/spatial-index/src/main/scala/com/azavea/hiveless/spatial/index/ST_Intersects.scala
@@ -31,6 +31,8 @@ class ST_Intersects extends HUDF[(ST_Intersects.Arg, ST_Intersects.Arg), Boolean
 object ST_Intersects {
   import UnaryDeserializer.Errors.ProductDeserializationError
 
+  // We could use Either[Extent, Geometry], but Either has no safe fall back CNil
+  // which may lead to derivation error messages rather than parsing
   type Arg = Extent :+: Geometry :+: CNil
 
   def parseGeometry(a: Arg): Option[Geometry] = a.select[Geometry].orElse(a.select[Extent].map(_.toPolygon()))