Liftable derivation WIP

Author: anatoliykmetyuk

tests/pos-macros/liftable-derivation/Macro_1.scala

@@ -0,0 +1,52 @@
+import scala.quoted._, scala.deriving._
+import scala.quoted.given
+
+import scala.reflect.ClassTag
+
+import Tuple.{ Head, Tail }
+import scala.compiletime.{ erasedValue, summonFrom }
+
+
+inline def mcr(given m: Mirror.ProductOf[Foo], m2: Mirror.ProductOf[Bar], m3: Mirror.ProductOf[Stuff.FooS], m4: Mirror.ProductOf[Stuff.BarS]): Any = ${mcrImpl(given 'm, 'm2, 'm3, 'm4)}
+def mcrImpl(given m: Expr[Mirror.ProductOf[Foo]], m2: Expr[Mirror.ProductOf[Bar]], m3: Expr[Mirror.ProductOf[Stuff.FooS]], m4: Expr[Mirror.ProductOf[Stuff.BarS]])(given ctx: QuoteContext): Expr[Any] =
+  val x: A = Foo(1, "foo")
+  val y: Stuff = Stuff.FooS(10)
+  Expr(y)
+
+sealed trait A
+case class Foo(x: Int, y: String) extends A
+case class Bar(a: String, b: Double) extends A
+
+enum Stuff {
+  case FooS(x: Int)
+  case BarS(y: String)
+}
+
+inline def summonInline[T] = summonFrom { case x: T => x }
+
+inline def summonAll[T <: Tuple]: List[?] = inline erasedValue[T] match
+  case _: Unit => Nil
+  case _: (t *: ts) => summonInline[t] :: summonAll[ts]
+
+inline given productLiftable[T <: Product: Type](given
+    m : Mirror.ProductOf[T],
+    em: Expr[Mirror.ProductOf[T]]): Liftable[T] = new Liftable[T] {
+  def toExpr(x: T) =
+    val genRepr = Tuple.fromProductTyped(x)
+    val liftables = summonAll[Tuple.Map[m.MirroredElemTypes, Liftable]]
+    val elemsWithLiftables = liftables.zip(genRepr.asInstanceOf[Product].productIterator.toList)
+    val tupleOfExprs = elemsWithLiftables.map {
+      case (l: Liftable[a], x) => l.toExpr(x.asInstanceOf[a])
+    }
+    val exprOfTuple = Expr.ofTuple(tupleOfExprs)
+    '{$em.fromProduct($exprOfTuple.asInstanceOf[Product])}
+}
+
+inline given sumLiftable[T: Type](given m: Mirror.SumOf[T]): Liftable[T] = new Liftable[T] {
+  def toExpr(x: T) =
+    val liftables = summonAll[Tuple.Map[m.MirroredElemTypes, Liftable]]
+    val tags = summonAll[Tuple.Map[m.MirroredElemTypes, ClassTag]]
+    tags.zip(liftables).flatMap { case (t: ClassTag[a], l: Liftable[?]) =>
+      t.unapply(x).map(xa => l.asInstanceOf[Liftable[a]].toExpr(xa)) }
+      .head.asInstanceOf[Expr[T]]
+}

tests/pos-macros/liftable-derivation/Test_2.scala

@@ -0,0 +1 @@
+@main def Test = println(mcr)