EnumEncoder.scala

case class DeserializeEnumExpression[T](child: Expression)(implicit clsTag: ClassTag[T]) extends UnaryExpression with NonSQLExpression {
  override def nullable: Boolean = true

  override protected def doGenCode(ctx: CodegenContext,
    ev: ExprCode): ExprCode = {
    val inputObject = child.genCode(ctx)
    val javaType = ctx.javaType(dataType)
    val code =
      s"""
         ${inputObject.code}
         final boolean ${ev.isNull} = ${inputObject.isNull};
         final $javaType ${ev.value} = ${ev.isNull} ? ${ctx.defaultValue(dataType)} : ${clsTag.runtimeClass.getName}$$.MODULE$$.fromValue(${inputObject.value});
        """
    ev.copy(code = code)
  }

  override def dataType: DataType = ObjectType(clsTag.runtimeClass)
}

object Enums {
  def enumEncoder[T <: GeneratedEnum](implicit cmp: GeneratedEnumCompanion[T], clsTag: ClassTag[T]): Encoder[T] = {
    val inputObject = BoundReference(0, ObjectType(clsTag.runtimeClass), nullable = true)
    val inputObject1 = BoundReference(0, DataTypes.IntegerType, nullable = true)
    val b = s"foo"

    new ExpressionEncoder[T](new StructType().add("val", DataTypes.IntegerType, true), false,
      serializer = Seq(
        Invoke(inputObject, "value", DataTypes.IntegerType, Nil, false, false)
      ),
      deserializer = DeserializeEnumExpression[T](inputObject1),
      clsTag
    )
  }

    def enumEncoder[T <: GeneratedEnum](implicit cmp: GeneratedEnumCompanion[T], clsTag: ClassTag[T]): Encoder[T] = {
    val inputObject = BoundReference(0, ObjectType(clsTag.runtimeClass), nullable = true)
    val inputObject1 = BoundReference(0, DataTypes.IntegerType, nullable = true)
    val b = s"foo"

    new ExpressionEncoder[T](new StructType().add("val", DataTypes.IntegerType, true), false,
      serializer = Seq(
        Invoke(inputObject, "value", DataTypes.IntegerType, Nil, false, false)
      ),
      deserializer = Invoke(Literal.fromObject(cmp), "fromName", ObjectType(clsTag.runtimeClass), Seq(inputObject1), false, false),
      clsTag
    )
  }
}