Merge pull request #232 from theiterators/dotty-value-enum

Basic implementation of ValueEnum for Scala 3

core/src/main/scala-3/pl/iterators/kebs/macros/enums/EnumEntryMacros.scala

@@ -1,33 +1,32 @@
 package pl.iterators.kebs.macros.enums
 
+import pl.iterators.kebs.enums.ValueEnum
 import scala.quoted._
 import scala.compiletime.{constValue, erasedValue, error, summonInline}
 import scala.deriving.Mirror
 import scala.reflect.{ClassTag, Enum}
 
 trait EnumLike[T] {
   def values: Array[T]
-  def valueOf(name: String): T
-  def fromOrdinal(ordinal: Int): T
+  def valueOf(name: String): T = values.find(_.toString == name).getOrElse(throw new IllegalArgumentException(s"enum case not found: $name"))
+  def fromOrdinal(ordinal: Int): T = values.lift(ordinal).getOrElse(throw new NoSuchElementException(ordinal.toString))
 }
 
 class EnumOf[E](val `enum`: EnumLike[E])
 
+inline private def widen[A, B] (a: A): A & B =
+  inline a match {
+  case b: B => b
+  }
+
 object EnumOf {
   inline given [E <: Enum](using m: Mirror.SumOf[E], ct: ClassTag[E]): EnumOf[E] = {
     val enumValues = summonCases[m.MirroredElemTypes, E]
     EnumOf[E](new EnumLike[E] {
       override def values: Array[E] = enumValues.toArray
-      override def valueOf(name: String): E = enumValues.find(_.toString == name).getOrElse(throw new IllegalArgumentException(s"enum case not found: $name"))
-      override def fromOrdinal(ordinal: Int): E = enumValues.lift(ordinal).getOrElse(throw new NoSuchElementException(ordinal.toString))
     })
   }
 
-  inline private def widen[A, B](a: A): A & B =
-    inline a match {
-      case b: B => b
-    }
-
   inline private def summonCases[T <: Tuple, A]: List[A] =
     inline erasedValue[T] match {
     case _: (h *: t) =>
@@ -37,6 +36,35 @@ object EnumOf {
         case x => error("Enums cannot include parameterized cases.")
       })
 
+    case _: EmptyTuple => Nil
+  }
+}
+
+trait ValueEnumLike[ValueType, T <: ValueEnum[ValueType]] {
+  def values: Array[T]
+  def valueOf(value: ValueType): T = values.find(_.value == value).getOrElse(throw new IllegalArgumentException(s"enum case not found: $value"))
+  def fromOrdinal(ordinal: Int): T = values.lift(ordinal).getOrElse(throw new NoSuchElementException(ordinal.toString))
+}
+
+class ValueEnumOf[V, E <: ValueEnum[V]](val `enum`: ValueEnumLike[V, E])
+
+object ValueEnumOf {
+  inline given [V, E <: ValueEnum[V] with Enum](using m: Mirror.SumOf[E], ct: ClassTag[E]): ValueEnumOf[V, E] = {
+    val enumValues = summonValueCases[m.MirroredElemTypes, V, E]
+    ValueEnumOf[V, E](new ValueEnumLike[V, E] {
+      override def values: Array[E] = enumValues.toArray
+    })
+  }
+
+  inline private def summonValueCases[T <: Tuple, V, A <: ValueEnum[V]]: List[A] =
+    inline erasedValue[T] match {
+    case _: (h *: t) =>
+      (inline summonInline[Mirror.Of[h]] match {
+        case m: Mirror.Singleton =>
+          widen[m.MirroredMonoType, A](m.fromProduct(EmptyTuple)) :: summonValueCases[t, V, A]
+        case x => error("Enums cannot include parameterized cases.")
+      })
+
     case _: EmptyTuple => Nil
   }
 }

core/src/main/scala-3/pl/iterators/kebs/macros/enums/ValueEnum.scala

@@ -0,0 +1,6 @@
+
+package pl.iterators.kebs.enums
+
+trait ValueEnum[ValueType] {
+  def value: ValueType
+}

core/src/test/scala-3/DerivingSpecification.scala

@@ -1,7 +1,8 @@
 import org.scalacheck.Prop.forAll
 import org.scalacheck.{Gen, Properties}
 import pl.iterators.kebs.macros.CaseClass1Rep
-import pl.iterators.kebs.macros.enums.EnumOf
+import pl.iterators.kebs.macros.enums.{EnumOf, ValueEnumOf}
+import pl.iterators.kebs.enums.ValueEnum
 
 object DerivingSpecification extends Properties("Deriving") {
   case class CC1Ex(whatever: String)
@@ -19,4 +20,15 @@ object DerivingSpecification extends Properties("Deriving") {
     val tc = implicitly[EnumOf[Color]]
     tc.`enum`.values.contains(color) && tc.`enum`.valueOf(color.toString) == color && tc.`enum`.fromOrdinal(color.ordinal) == color
   }
+
+  enum ColorButRGB(val value: Int) extends ValueEnum[Int] {
+    case Red extends ColorButRGB(0xFF0000)
+    case Green extends ColorButRGB(0x00FF00)
+    case Blue extends ColorButRGB(0x0000FF)
+  }
+
+  property("ValueEnumOf derives properly for an enum") = forAll(Gen.oneOf(ColorButRGB.values.toList)) { (color: ColorButRGB) =>
+    val tc = implicitly[ValueEnumOf[Int, ColorButRGB]]
+    tc.`enum`.values.contains(color) && tc.`enum`.valueOf(color.value) == color && tc.`enum`.fromOrdinal(color.ordinal) == color
+  }
 }