Replace inheritance with ifdef for version specific Eithered

Author: rayrobdod

Base/src/main/scala-2/typeclass/VersionSpecificEithered.scala

@@ -1,6 +1,8 @@
 package name.rayrobdod.stringContextParserCombinator
 package typeclass
 
+import com.eed3si9n.ifdef.ifdef
+
 /**
  * Describes how to represent a result that may be one of two results
  *
@@ -66,7 +68,7 @@ trait BiEithered[Expr[_], A, B, Z]
  * Predefined implicit implementations of Eithered
  * and methods to create new Eithereds
  */
-object Eithered extends VersionSpecificEithered {
+object Eithered extends LowPrioEithered {
 	/**
 	 * Constructs an `Eithered` from a set of functions corresponding to each of Eithered's methods
 	 */
@@ -78,6 +80,46 @@ object Eithered extends VersionSpecificEithered {
 		new Apply()
 	}
 
+	@ifdef("scalaEpochVersion:2")
+	implicit def unitUnit:Eithered[Unit, Unit, Unit] = symmetric[Unit]
+	@ifdef("scalaBinaryVersion:3")
+	implicit def unitUnit:Eithered[Unit, Unit, Unit] = Eithered.generic
+
+	@ifdef("scalaEpochVersion:2")
+	implicit def unitGeneric[B, Z](implicit ev:Optionally[B, Z]):Eithered[Unit, B, Z] = Eithered(_ => ev.none, ev.some _)
+	@ifdef("scalaEpochVersion:2")
+	implicit def genericUnit[A, Z](implicit ev:Optionally[A, Z]):Eithered[A, Unit, Z] = Eithered(ev.some _, _ => ev.none)
+
+	@ifdef("scalaBinaryVersion:3")
+	implicit def unitAny[B, Z](implicit ev:Optionally[B, Z]):Eithered[Unit, B, Z] = Eithered(_ => ev.none, ev.some _)
+	@ifdef("scalaBinaryVersion:3")
+	implicit def anyUnit[A, Z](implicit ev:Optionally[A, Z]):Eithered[A, Unit, Z] = Eithered(ev.some _, _ => ev.none)
+
+	/**
+	 * @version 0.1.1
+	 */
+	@ifdef("scalaEpochVersion:2")
+	trait Eithereds[Expr[+_]] {
+		def splicePiece[A]: Eithered[Expr[A], Expr[Iterable[A]], Repeated.SplicePiece[Expr, A]]
+	}
+	/**
+	 * @version 0.1.1
+	 */
+	@ifdef("scalaEpochVersion:2")
+	def forContext(c:scala.reflect.macros.blackbox.Context):Eithereds[c.Expr] = {
+		new Eithereds[c.Expr] {
+			def splicePiece[A]: Eithered[c.Expr[A], c.Expr[Iterable[A]], Repeated.SplicePiece[c.Expr, A]] =
+				Eithered(new Repeated.SplicePiece.One(_), new Repeated.SplicePiece.Many(_))
+		}
+	}
+
+	/**
+	 * @version 0.1.1
+	 */
+	@ifdef("scalaBinaryVersion:3")
+	def quotedSplicePiece[A]: Eithered[scala.quoted.Expr[A], scala.quoted.Expr[Iterable[A]], Repeated.SplicePiece[scala.quoted.Expr, A]] =
+			Eithered(new Repeated.SplicePiece.One(_), new Repeated.SplicePiece.Many(_))
+
 	/**
 	 * An Eithered that wraps the value in a `scala.Either`
 
@@ -98,11 +140,27 @@ object Eithered extends VersionSpecificEithered {
 	def discriminatedUnion[A, B]:Eithered[A, B, Either[A, B]] = Eithered(Left.apply _, Right.apply _)
 }
 
+private[typeclass] trait LowPrioEithered {
+	@ifdef("scalaEpochVersion:2")
+	implicit def symmetric[A]:Eithered[A, A, A] = Eithered(Predef.identity _, Predef.identity _)
+
+	/**
+	 * The fallback Eithered;
+	 * creates a union type of the two component types.
+	 *
+	 * Since the union of a type with itself is equivalent to that same type,
+	 * if this Eithered is used for two parsers of the same type,
+	 * then the result is a parser of that type.
+	 */
+	@ifdef("scalaBinaryVersion:3")
+	implicit def generic[A, B]:Eithered[A, B, A | B] = Eithered.apply(Predef.identity _, Predef.identity _)
+}
+
 /**
  * Predefined implicit implementations of ContraEithered
  * and methods to create new ContraEithereds
  */
-object ContraEithered extends VersionSpecificContraEithered {
+object ContraEithered extends LowPrioContraEithered {
 	/**
 	 * Constructs an `ContraEithered` from a set of functions corresponding to each of ContraEithered's methods
 	 */
@@ -116,13 +174,45 @@ object ContraEithered extends VersionSpecificContraEithered {
 		}
 		new Apply()
 	}
+
+	@ifdef("scalaEpochVersion:2")
+	trait ContraEithereds[Expr[_]] extends LowPrioContraEithereds[Expr] {
+		implicit def unitUnit:ContraEithered[Expr, Unit, Unit, Unit]
+	}
+	@ifdef("scalaEpochVersion:2")
+	private[typeclass]
+	trait LowPrioContraEithereds[Expr[_]] {
+		implicit def symmetric[A]:ContraEithered[Expr, A, A, A]
+	}
+
+	@ifdef("scalaEpochVersion:2")
+	def forContext(c:scala.reflect.macros.blackbox.Context):ContraEithereds[c.Expr] = {
+		val backing = BiEithered.forContext(c)
+
+		new ContraEithereds[c.Expr] {
+			implicit override def unitUnit:ContraEithered[c.Expr, Unit, Unit, Unit] = backing.unitUnit
+			implicit override def symmetric[A]:ContraEithered[c.Expr, A, A, A] = backing.symmetric[A]
+		}
+	}
+
+	@ifdef("scalaBinaryVersion:3")
+	implicit def quotedUnitUnit(implicit quotes:scala.quoted.Quotes):ContraEithered[scala.quoted.Expr, Unit, Unit, Unit] = quotedSymmetric[Unit]
+
+	implicit def idUnitUnit:ContraEithered[Id, Unit, Unit, Unit] = idSymmetric[Unit]
+}
+
+private[typeclass] trait LowPrioContraEithered {
+	@ifdef("scalaBinaryVersion:3")
+	implicit def quotedSymmetric[A](implicit quotes:scala.quoted.Quotes):ContraEithered[scala.quoted.Expr, A, A, A] = BiEithered.quotedSymmetric
+
+	implicit def idSymmetric[A]:ContraEithered[Id, A, A, A] = BiEithered.idSymmetric
 }
 
 /**
  * Predefined implicit implementations of BiEithered
  * and methods to create new BiEithereds
  */
-object BiEithered extends VersionSpecificBiEithered {
+object BiEithered extends LowPrioBiEithered {
 	/**
 	 * Constructs an `BiEithered` from a set of functions corresponding to each of BiEithered's methods
 	 */
@@ -142,4 +232,76 @@ object BiEithered extends VersionSpecificBiEithered {
 		new Apply()
 	}
 
+	@ifdef("scalaEpochVersion:2")
+	trait BiEithereds[Expr[_]] extends LowPrioBiEithereds[Expr] {
+		implicit def unitUnit:BiEithered[Expr, Unit, Unit, Unit]
+	}
+	@ifdef("scalaEpochVersion:2")
+	private[typeclass]
+	trait LowPrioBiEithereds[Expr[_]] {
+		implicit def symmetric[A]:BiEithered[Expr, A, A, A]
+	}
+	@ifdef("scalaEpochVersion:2")
+	def forContext(c:scala.reflect.macros.blackbox.Context):BiEithereds[c.Expr] = {
+		new BiEithereds[c.Expr] {
+			override def unitUnit:BiEithered[c.Expr, Unit, Unit, Unit] = this.symmetric[Unit]
+
+			implicit override def symmetric[A]:BiEithered[c.Expr, A, A, A] = {
+				val exprTrue = c.Expr[Boolean](c.universe.Liftable.liftBoolean(true))
+
+				BiEithered.apply[c.Expr, A, A, A](
+					Predef.identity _,
+					Predef.identity _,
+					PartialExprFunction.identity(exprTrue),
+					PartialExprFunction.identity(exprTrue)
+				)
+			}
+		}
+	}
+
+	@ifdef("scalaBinaryVersion:3")
+	implicit def quotedUnitUnit(implicit quotes:scala.quoted.Quotes):BiEithered[scala.quoted.Expr, Unit, Unit, Unit] = quotedSymmetric[Unit]
+
+	@ifdef("scalaBinaryVersion:3")
+	implicit def eitherUnitAny[Expr[_], B, Z](implicit ev:BiOptionally[Expr, B, Z]):BiEithered[Expr, Unit, B, Z] = BiEithered(
+		_ => ev.none,
+		ev.some _,
+		PartialExprFunction[Expr, Z, Unit](
+			ev.contraNone,
+			_ => ()
+		),
+		ev.contraSome,
+	)
+	@ifdef("scalaBinaryVersion:3")
+	implicit def eitherAnyUnit[Expr[_], A, Z](implicit ev:BiOptionally[Expr, A, Z]):BiEithered[Expr, A, Unit, Z] = BiEithered(
+		ev.some _,
+		_ => ev.none,
+		ev.contraSome,
+		PartialExprFunction[Expr, Z, Unit](
+			ev.contraNone,
+			_ => ()
+		),
+	)
+
+	@ifdef("scalaBinaryVersion:3")
+	implicit def idUnitUnit:BiEithered[Id, Unit, Unit, Unit] = idSymmetric[Unit]
+}
+
+private[typeclass] trait LowPrioBiEithered {
+	@ifdef("scalaBinaryVersion:3")
+	implicit def quotedSymmetric[A](implicit quotes:scala.quoted.Quotes):BiEithered[scala.quoted.Expr, A, A, A] = BiEithered.apply(
+		Predef.identity _,
+		Predef.identity _,
+		PartialExprFunction.identity(scala.quoted.Expr(true)),
+		PartialExprFunction.identity(scala.quoted.Expr(true)),
+	)
+
+	implicit def idSymmetric[A]:BiEithered[Id, A, A, A] = {
+		BiEithered.apply[Id, A, A, A](
+			Predef.identity _,
+			Predef.identity _,
+			PartialExprFunction.identity[Id, A](true),
+			PartialExprFunction.identity[Id, A](true),
+		)
+	}
 }