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Synthesise Mirror.Sum for nested hierarchies
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,129 @@ | ||
| import scala.compiletime.* | ||
| import scala.deriving.* | ||
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| object OriginalReport: | ||
| sealed trait TreeValue | ||
| sealed trait SubLevel extends TreeValue | ||
| case class Leaf1(value: String) extends TreeValue | ||
| case class Leaf2(value: Int) extends SubLevel | ||
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| // Variants from the initial failure in akka.event.LogEvent | ||
| object FromAkkaCB: | ||
| sealed trait A | ||
| sealed trait B extends A | ||
| sealed trait C extends A | ||
| case class D() extends B, C | ||
| case class E() extends C, B | ||
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| object FromAkkaCB2: | ||
| sealed trait A | ||
| sealed trait N extends A | ||
| case class B() extends A | ||
| case class C() extends A, N | ||
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| object FromAkkaCB3: | ||
| sealed trait A | ||
| case class B() extends A | ||
| case class C() extends A | ||
| class D extends C // ignored pattern: class extending a case class | ||
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| object FromAkkaCB4: | ||
| sealed trait A | ||
| sealed trait N extends A | ||
| case class B() extends A | ||
| case class C() extends A | ||
| class D extends C, N // ignored | ||
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| object FromAkkaCB5: | ||
| sealed trait A | ||
| sealed trait N extends A | ||
| case class B() extends A | ||
| case class C() extends A | ||
| class D extends N // ignored | ||
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| object Test: | ||
| def main(args: Array[String]): Unit = | ||
| testOriginalReport() | ||
| testFromAkkaCB() | ||
| testFromAkkaCB2() | ||
| end main | ||
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| def testOriginalReport() = | ||
| import OriginalReport._ | ||
| val m = summon[Mirror.SumOf[TreeValue]] | ||
| given Show[TreeValue] = Show.derived[TreeValue] | ||
| val leaf1 = Leaf1("1") | ||
| val leaf2 = Leaf2(2) | ||
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| assertEq(List(leaf1, leaf2).map(m.ordinal), List(1, 0)) | ||
| assertShow[TreeValue](leaf1, "[1] Leaf1(value = \"1\")") | ||
| assertShow[TreeValue](leaf2, "[0] [0] Leaf2(value = 2)") | ||
| end testOriginalReport | ||
|
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| def testFromAkkaCB() = | ||
| import FromAkkaCB._ | ||
| val m = summon[Mirror.SumOf[A]] | ||
| given Show[A] = Show.derived[A] | ||
| val d = D() | ||
| val e = E() | ||
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| assertEq(List(d, e).map(m.ordinal), List(0, 0)) | ||
| assertShow[A](d, "[0] [0] D") | ||
| assertShow[A](e, "[0] [1] E") | ||
| end testFromAkkaCB | ||
|
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| def testFromAkkaCB2() = | ||
| import FromAkkaCB2._ | ||
| val m = summon[Mirror.SumOf[A]] | ||
| val n = summon[Mirror.SumOf[N]] | ||
| given Show[A] = Show.derived[A] | ||
| val b = B() | ||
| val c = C() | ||
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| assertEq(List(b, c).map(m.ordinal), List(1, 0)) | ||
| assertShow[A](b, "[1] B") | ||
| assertShow[A](c, "[0] [0] C") | ||
| end testFromAkkaCB2 | ||
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| def assertEq[A](obt: A, exp: A) = assert(obt == exp, s"$obt != $exp (obtained != expected)") | ||
| def assertShow[A: Show](x: A, s: String) = assertEq(Show.show(x), s) | ||
| end Test | ||
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| trait Show[-T]: | ||
| def show(x: T): String | ||
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| object Show: | ||
| given Show[Int] with { def show(x: Int) = s"$x" } | ||
| given Show[Char] with { def show(x: Char) = s"'$x'" } | ||
| given Show[String] with { def show(x: String) = s"$"$x$"" } | ||
|
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| inline def show[T](x: T): String = summonInline[Show[T]].show(x) | ||
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| transparent inline def derived[T](implicit ev: Mirror.Of[T]): Show[T] = new { | ||
| def show(x: T): String = inline ev match { | ||
| case m: Mirror.ProductOf[T] => showProduct(x.asInstanceOf[Product], m) | ||
| case m: Mirror.SumOf[T] => showCases[m.MirroredElemTypes](0)(x, m.ordinal(x)) | ||
| } | ||
| } | ||
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| transparent inline def showProduct[T](x: Product, m: Mirror.ProductOf[T]): String = | ||
| constValue[m.MirroredLabel] + showElems[m.MirroredElemTypes, m.MirroredElemLabels](0, Nil)(x) | ||
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| transparent inline def showElems[Elems <: Tuple, Labels <: Tuple](n: Int, elems: List[String])(x: Product): String = | ||
| inline (erasedValue[Labels], erasedValue[Elems]) match { | ||
| case _: (label *: labels, elem *: elems) => | ||
| val value = show(x.productElement(n).asInstanceOf[elem]) | ||
| showElems[elems, labels](n + 1, s"${constValue[label]} = $value" :: elems)(x) | ||
| case _: (EmptyTuple, EmptyTuple) => | ||
| if elems.isEmpty then "" else elems.mkString(s"(", ", ", ")") | ||
| } | ||
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| transparent inline def showCases[Alts <: Tuple](n: Int)(x: Any, ord: Int): String = | ||
| inline erasedValue[Alts] match { | ||
| case _: (alt *: alts) => | ||
| if (ord == n) summonFrom { | ||
| case m: Mirror.Of[`alt`] => s"[$ord] " + derived[alt](using m).show(x.asInstanceOf[alt]) | ||
| } else showCases[alts](n + 1)(x, ord) | ||
| case _: EmptyTuple => throw new MatchError(x) | ||
| } | ||
| end Show |