Add MatchTypeCase to Tasty Reflect

Author: abgruszecki

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -1881,6 +1881,47 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
       end extension
     end MatchTypeMethods
 
+    type MatchTypeCase = dotc.core.Types.Type
+
+    object MatchTypeCaseTypeTest extends TypeTest[TypeRepr, MatchTypeCase]:
+      def unapply(x: TypeRepr): Option[MatchTypeCase & x.type] =
+        MatchTypeCase.unapply(x.asInstanceOf[MatchTypeCase]).map(_ => x.asInstanceOf[MatchTypeCase & x.type])
+    end MatchTypeCaseTypeTest
+
+    object MatchTypeCase extends MatchTypeCaseModule:
+      def apply(pattern: TypeRepr, body: TypeRepr): MatchTypeCase =
+        Types.AppliedType(ctx.definitions.MatchCaseClass.typeRef, List(pattern, body))
+
+      def apply(
+        paramNames: List[String],
+        boundsFn: TypeLambda => List[TypeBounds],
+        patternFn: TypeLambda => TypeRepr,
+        bodyFn: TypeLambda => TypeRepr,
+      ): MatchTypeCase =
+        reflect.TypeLambda(paramNames, boundsFn, tl => MatchTypeCase(patternFn(tl), bodyFn(tl)))
+
+      def unapply(x: MatchTypeCase): Option[(List[String], List[TypeBounds], TypeRepr, TypeRepr)] = x match
+        case AppliedType(tycon, Seq(from, to)) if tycon.isRef(ctx.definitions.MatchCaseClass) =>
+          Some((Nil, Nil, from, to))
+        case TypeLambda(paramNames, paramBounds, AppliedType(tycon, Seq(from, to))) if tycon.isRef(ctx.definitions.MatchCaseClass) =>
+          Some((paramNames.map(_.toString), paramBounds, from, to))
+        case _ =>
+          None
+    end MatchTypeCase
+
+    given MatchTypeCaseMethods: MatchTypeCaseMethods with
+      extension (self: MatchTypeCase):
+        def paramNames: List[String] = unwrap(self)(0)
+        def paramBounds: List[TypeBounds] = unwrap(self)(1)
+        def pattern: TypeRepr = unwrap(self)(2)
+        def body: TypeRepr = unwrap(self)(3)
+      end extension
+
+      private def unwrap(x: MatchTypeCase) =
+        // should never throw within limits of the API
+        MatchTypeCase.unapply(x).get
+    end MatchTypeCaseMethods
+
     type ByNameType = dotc.core.Types.ExprType
 
     object ByNameTypeTypeTest extends TypeTest[TypeRepr, ByNameType]:

library/src/scala/quoted/Quotes.scala

@@ -2442,7 +2442,7 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
     /** Methods of the module object `val MatchType` */
     trait MatchTypeModule { this: MatchType.type =>
       def apply(bound: TypeRepr, scrutinee: TypeRepr, cases: List[TypeRepr]): MatchType
-      def unapply(x: MatchType): Option[(TypeRepr, TypeRepr, List[TypeRepr])]
+      def unapply(x: MatchType): Option[(TypeRepr, TypeRepr, List[MatchTypeCase])]
     }
 
     /** Makes extension methods on `MatchType` available without any imports */
@@ -2453,10 +2453,46 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
       extension (self: MatchType):
         def bound: TypeRepr
         def scrutinee: TypeRepr
-        def cases: List[TypeRepr]
+        def cases: List[MatchTypeCase]
       end extension
     end MatchTypeMethods
 
+    /** Case of a match type `case U => S`. */
+    type MatchTypeCase <: TypeRepr
+
+    /** `TypeTest` that allows testing at runtime in a pattern match if a `TypeRepr` is a `MatchTypeCase` */
+    given MatchTypeCaseTypeTest: TypeTest[TypeRepr, MatchTypeCase]
+
+    /** Module object of `case U => S` */
+    val MatchTypeCase: MatchTypeCaseModule
+
+    /** Methods of the module object of `case U => S` */
+    trait MatchTypeCaseModule { this: MatchTypeCase.type =>
+      def apply(pattern: TypeRepr, body: TypeRepr): MatchTypeCase
+
+      def apply(
+        paramNames: List[String],
+        boundsFn: TypeLambda => List[TypeBounds],
+        patternFn: TypeLambda => TypeRepr,
+        bodyFn: TypeLambda => TypeRepr,
+      ): MatchTypeCase
+
+      def unapply(x: MatchTypeCase): Option[(List[String], List[TypeBounds], TypeRepr, TypeRepr)]
+    }
+
+    /** Makes extension methods on `MatchTypeCase` available without any imports */
+    given MatchTypeCaseMethods: MatchTypeCaseMethods
+
+    /** Extension methods of `MatchTypeCase` */
+    trait MatchTypeCaseMethods:
+      extension (self: MatchTypeCase):
+        def paramNames: List[String]
+        def paramBounds: List[TypeBounds]
+        def pattern: TypeRepr
+        def body: TypeRepr
+      end extension
+    end MatchTypeCaseMethods
+
     /** Type of a by by name parameter */
     type ByNameType <: TypeRepr
 

scala3doc/src/dotty/dokka/tasty/SyntheticSupport.scala

@@ -96,13 +96,3 @@ trait SyntheticsSupport:
     given dotc.core.Contexts.Context = qctx.asInstanceOf[scala.quoted.runtime.impl.QuotesImpl].ctx
     val cSym = c.symbol.asInstanceOf[dotc.core.Symbols.Symbol]
     cSym.typeRef.appliedTo(cSym.typeParams.map(_.typeRef)).asInstanceOf[TypeRepr]
-
-  object MatchTypeCase:
-    def unapply(tpe: TypeRepr): Option[(TypeRepr, TypeRepr)] =
-      tpe match
-        case AppliedType(t, Seq(from, to)) /*if t == MatchCaseType*/ =>
-            Some((from, to))
-        case TypeLambda(paramNames, paramTypes, AppliedType(t, Seq(from, to))) /*if t == MatchCaseType*/ =>
-            Some((from, to))
-        case _ =>
-          None

scala3doc/src/dotty/dokka/tasty/TypesSupport.scala

@@ -240,7 +240,7 @@ trait TypesSupport:
 
       case MatchType(bond, sc, cases) =>
         val casesTexts = cases.flatMap {
-          case MatchTypeCase(from, to) =>
+          case MatchTypeCase(_, _, from, to) =>
             texts("  case ") ++ inner(from) ++ texts(" => ") ++ inner(to) ++ texts("\n")
         }
         inner(sc) ++ texts(" match {\n") ++ casesTexts ++ texts("}")

tests/run-macros/tasty-construct-types/Macro_1.scala

@@ -33,10 +33,17 @@ object Macros {
         TypeRepr.of[Int],
         TypeRepr.of[List[8]],
         List(
-          TypeLambda(
+          MatchTypeCase(
             List("t"),
             _ => List(TypeBounds(TypeRepr.of[Nothing], TypeRepr.of[Any])),
-            tl => TypeRepr.of[scala.runtime.MatchCase].appliedTo(List(TypeRepr.of[List].appliedTo(tl.param(0)), tl.param(0)))))
+            tl => TypeRepr.of[List].appliedTo(tl.param(0)),
+            tl => tl.param(0),
+          ),
+          MatchTypeCase(
+            TypeRepr.of[Int],
+            TypeRepr.of[Int],
+          )
+        )
       )
 
     assert(x1T =:= TypeRepr.of[1])
@@ -46,7 +53,10 @@ object Macros {
     assert(x5T =:= TypeRepr.of[RefineMe { type T = Int }])
     assert(x6T =:= TypeRepr.of[List[Int]])
     assert(x7T =:= TypeRepr.of[7 @TestAnnotation])
-    assert(x8T =:= TypeRepr.of[List[8] match { case List[t] => t }])
+    assert(x8T =:= TypeRepr.of[List[8] match {
+      case List[t] => t
+      case Int => Int
+    }])
 
     '{
       println("Ok")