Merge pull request #9914 from dotty-staging/rework-reflect-constant

Rework Reflect Constant

Author: nicolasstucki

community-build/community-projects/scalatest

@@ -2061,16 +2061,91 @@ class QuoteContextImpl private (ctx: Context) extends QuoteContext:
     type Constant = dotc.core.Constants.Constant
 
     object Constant extends ConstantModule:
-      def apply(x: Unit | Null | Int | Boolean | Byte | Short | Int | Long | Float | Double | Char | String | Type): Constant =
-        dotc.core.Constants.Constant(x)
-      def unapply(constant: Constant): Option[Unit | Null | Int | Boolean | Byte | Short | Int | Long | Float | Double | Char | String | Type] =
-        Some(constant.value.asInstanceOf[Unit | Null | Int | Boolean | Byte | Short | Int | Long | Float | Double | Char | String | Type])
-      object ClassTag extends ClassTagModule:
-        def apply[T](using x: Type): Constant = dotc.core.Constants.Constant(x)
+
+      object Boolean extends ConstantBooleanModule:
+        def apply(x: Boolean): Constant = dotc.core.Constants.Constant(x)
+        def unapply(constant: Constant): Option[Boolean] =
+          if constant.tag == dotc.core.Constants.BooleanTag then Some(constant.booleanValue)
+          else None
+      end Boolean
+
+      object Byte extends ConstantByteModule:
+        def apply(x: Byte): Constant = dotc.core.Constants.Constant(x)
+        def unapply(constant: Constant): Option[Byte] =
+          if constant.tag == dotc.core.Constants.ByteTag then Some(constant.byteValue)
+          else None
+      end Byte
+
+      object Short extends ConstantShortModule:
+        def apply(x: Short): Constant = dotc.core.Constants.Constant(x)
+        def unapply(constant: Constant): Option[Short] =
+          if constant.tag == dotc.core.Constants.ShortTag then Some(constant.shortValue)
+          else None
+      end Short
+
+      object Int extends ConstantIntModule:
+        def apply(x: Int): Constant = dotc.core.Constants.Constant(x)
+        def unapply(constant: Constant): Option[Int] =
+          if constant.tag == dotc.core.Constants.IntTag then Some(constant.intValue)
+          else None
+      end Int
+
+      object Long extends ConstantLongModule:
+        def apply(x: Long): Constant = dotc.core.Constants.Constant(x)
+        def unapply(constant: Constant): Option[Long] =
+          if constant.tag == dotc.core.Constants.LongTag then Some(constant.longValue)
+          else None
+      end Long
+
+      object Float extends ConstantFloatModule:
+        def apply(x: Float): Constant = dotc.core.Constants.Constant(x)
+        def unapply(constant: Constant): Option[Float] =
+          if constant.tag == dotc.core.Constants.FloatTag then Some(constant.floatValue)
+          else None
+      end Float
+
+      object Double extends ConstantDoubleModule:
+        def apply(x: Double): Constant = dotc.core.Constants.Constant(x)
+        def unapply(constant: Constant): Option[Double] =
+          if constant.tag == dotc.core.Constants.DoubleTag then Some(constant.doubleValue)
+          else None
+      end Double
+
+      object Char extends ConstantCharModule:
+        def apply(x: Char): Constant = dotc.core.Constants.Constant(x)
+        def unapply(constant: Constant): Option[Char] =
+          if constant.tag == dotc.core.Constants.CharTag then Some(constant.charValue)
+          else None
+      end Char
+
+      object String extends ConstantStringModule:
+        def apply(x: String): Constant = dotc.core.Constants.Constant(x)
+        def unapply(constant: Constant): Option[String] =
+          if constant.tag == dotc.core.Constants.StringTag then Some(constant.stringValue)
+          else None
+      end String
+
+      object Unit extends ConstantUnitModule:
+        def apply(): Constant = dotc.core.Constants.Constant(())
+        def unapply(constant: Constant): Boolean =
+          constant.tag == dotc.core.Constants.UnitTag
+      end Unit
+
+      object Null extends ConstantNullModule:
+        def apply(): Constant = dotc.core.Constants.Constant(null)
+        def unapply(constant: Constant): Boolean =
+          constant.tag == dotc.core.Constants.NullTag
+      end Null
+
+      object ClassOf extends ConstantClassOfModule:
+        def apply(x: Type): Constant =
+          // TODO check that the type is a valid class when creating this constant or let Ycheck do it?
+          dotc.core.Constants.Constant(x)
         def unapply(constant: Constant): Option[Type] =
           if constant.tag == dotc.core.Constants.ClazzTag then Some(constant.typeValue)
           else None
-      end ClassTag
+      end ClassOf
+
     end Constant
 
     object ConstantMethodsImpl extends ConstantMethods:

community-build/community-projects/shapeless

@@ -60,13 +60,13 @@ object Expr {
   /** Returns a null expresssion equivalent to `'{null}` */
   def `null`: QuoteContext ?=> quoted.Expr[Null] = qctx ?=> {
     import qctx.tasty._
-    Literal(Constant(null)).seal.asInstanceOf[quoted.Expr[Null]]
+    Literal(Constant.Null()).seal.asInstanceOf[quoted.Expr[Null]]
   }
 
   /** Returns a unit expresssion equivalent to `'{}` or `'{()}` */
   def Unit: QuoteContext ?=> quoted.Expr[Unit] = qctx ?=> {
     import qctx.tasty._
-    Literal(Constant(())).seal.asInstanceOf[quoted.Expr[Unit]]
+    Literal(Constant.Unit()).seal.asInstanceOf[quoted.Expr[Unit]]
   }
 
 }

community-build/community-projects/upickle

@@ -22,38 +22,66 @@ object Liftable {
   // IMPORTANT Keep in sync with tests/run-staging/liftables.scala
 
   /** Default liftable for Boolean */
-  given BooleanLiftable[T <: Boolean] as Liftable[T] = new PrimitiveLiftable
+  given BooleanLiftable[T <: Boolean] as Liftable[T] {
+    def toExpr(x: T) =
+      import qctx.tasty._
+      Literal(Constant.Boolean(x)).seal.asInstanceOf[Expr[T]]
+  }
 
   /** Default liftable for Byte */
-  given ByteLiftable[T <: Byte] as Liftable[T] = new PrimitiveLiftable
+  given ByteLiftable[T <: Byte] as Liftable[T] {
+    def toExpr(x: T) =
+      import qctx.tasty._
+      Literal(Constant.Byte(x)).seal.asInstanceOf[Expr[T]]
+  }
 
   /** Default liftable for Short */
-  given ShortLiftable[T <: Short] as Liftable[T] = new PrimitiveLiftable
+  given ShortLiftable[T <: Short] as Liftable[T] {
+    def toExpr(x: T) =
+      import qctx.tasty._
+      Literal(Constant.Short(x)).seal.asInstanceOf[Expr[T]]
+  }
 
   /** Default liftable for Int */
-  given IntLiftable[T <: Int] as Liftable[T] = new PrimitiveLiftable
+  given IntLiftable[T <: Int] as Liftable[T] {
+    def toExpr(x: T) =
+      import qctx.tasty._
+      Literal(Constant.Int(x)).seal.asInstanceOf[Expr[T]]
+  }
 
   /** Default liftable for Long */
-  given LongLiftable[T <: Long] as Liftable[T] = new PrimitiveLiftable
+  given LongLiftable[T <: Long] as Liftable[T] {
+    def toExpr(x: T) =
+      import qctx.tasty._
+      Literal(Constant.Long(x)).seal.asInstanceOf[Expr[T]]
+  }
 
   /** Default liftable for Float */
-  given FloatLiftable[T <: Float] as Liftable[T] = new PrimitiveLiftable
+  given FloatLiftable[T <: Float] as Liftable[T] {
+    def toExpr(x: T) =
+      import qctx.tasty._
+      Literal(Constant.Float(x)).seal.asInstanceOf[Expr[T]]
+  }
 
   /** Default liftable for Double */
-  given DoubleLiftable[T <: Double] as Liftable[T] = new PrimitiveLiftable
+  given DoubleLiftable[T <: Double] as Liftable[T] {
+    def toExpr(x: T) =
+      import qctx.tasty._
+      Literal(Constant.Double(x)).seal.asInstanceOf[Expr[T]]
+  }
 
   /** Default liftable for Char */
-  given CharLiftable[T <: Char] as Liftable[T] = new PrimitiveLiftable
+  given CharLiftable[T <: Char] as Liftable[T] {
+    def toExpr(x: T) =
+      import qctx.tasty._
+      Literal(Constant.Char(x)).seal.asInstanceOf[Expr[T]]
+  }
 
   /** Default liftable for String */
-  given StringLiftable[T <: String] as Liftable[T] = new PrimitiveLiftable
-
-  /** Lift a literal constant value */
-  private class PrimitiveLiftable[T <: Unit | Null | Int | Boolean | Byte | Short | Int | Long | Float | Double | Char | String] extends Liftable[T] {
-    def toExpr(x: T) = qctx ?=> {
+  given StringLiftable[T <: String] as Liftable[T] {
+    def toExpr(x: T) =
       import qctx.tasty._
-      Literal(Constant(x)).seal.asInstanceOf[Expr[T]]
-    }
+      Literal(Constant.String(x)).seal.asInstanceOf[Expr[T]]
   }
 
   /** Default liftable for Class[T] */

community-build/community-projects/utest

@@ -2317,25 +2317,144 @@ trait Reflection { reflection =>
   /** Constant value represented as the constant itself */
   type Constant <: AnyRef
 
-  /** Module of Constant literals */
+  /** Constant value represented as the constant itself */
   val Constant: ConstantModule
 
+  /** Constant value represented as the constant itself */
   trait ConstantModule { this: Constant.type =>
 
-    def apply(x: Unit | Null | Int | Boolean | Byte | Short | Int | Long | Float | Double | Char | String | Type): Constant
+    /** Constant Boolean value */
+    val Boolean: ConstantBooleanModule
+
+    /** Constant Boolean value */
+    trait ConstantBooleanModule { this: Boolean.type =>
+      /** Create a constant Boolean value */
+      def apply(x: Boolean): Constant
+      /** Match Boolean value constant and extract its value */
+      def unapply(constant: Constant): Option[Boolean]
+    }
+
+    /** Constant Byte value */
+    val Byte: ConstantByteModule
+
+    /** Constant Byte value */
+    trait ConstantByteModule { this: Byte.type =>
+      /** Create a constant Byte value */
+      def apply(x: Byte): Constant
+      /** Match Byte value constant and extract its value */
+      def unapply(constant: Constant): Option[Byte]
+    }
+
+    /** Constant Short value */
+    val Short: ConstantShortModule
+
+    /** Constant Short value */
+    trait ConstantShortModule { this: Short.type =>
+      /** Create a constant Short value */
+      def apply(x: Short): Constant
+      /** Match Short value constant and extract its value */
+      def unapply(constant: Constant): Option[Short]
+    }
+
+    /** Constant Int value */
+    val Int: ConstantIntModule
+
+    /** Constant Int value */
+    trait ConstantIntModule { this: Int.type =>
+      /** Create a constant Int value */
+      def apply(x: Int): Constant
+      /** Match Int value constant and extract its value */
+      def unapply(constant: Constant): Option[Int]
+    }
+
+    /** Constant Long value */
+    val Long: ConstantLongModule
+
+    /** Constant Long value */
+    trait ConstantLongModule { this: Long.type =>
+      /** Create a constant Long value */
+      def apply(x: Long): Constant
+      /** Match Long value constant and extract its value */
+      def unapply(constant: Constant): Option[Long]
+    }
+
+    /** Constant Float value */
+    val Float: ConstantFloatModule
 
-    def unapply(constant: Constant): Option[Unit | Null | Int | Boolean | Byte | Short | Int | Long | Float | Double | Char | String | Type]
+    /** Constant Float value */
+    trait ConstantFloatModule { this: Float.type =>
+      /** Create a constant Float value */
+      def apply(x: Float): Constant
+      /** Match Float value constant and extract its value */
+      def unapply(constant: Constant): Option[Float]
+    }
+
+    /** Constant Double value */
+    val Double: ConstantDoubleModule
+
+    /** Constant Double value */
+    trait ConstantDoubleModule { this: Double.type =>
+      /** Create a constant Double value */
+      def apply(x: Double): Constant
+      /** Match Double value constant and extract its value */
+      def unapply(constant: Constant): Option[Double]
+    }
+
+    /** Constant Char value */
+    val Char: ConstantCharModule
 
-    /** Module of ClassTag literals */
-    val ClassTag: ClassTagModule
+    /** Constant Char value */
+    trait ConstantCharModule { this: Char.type =>
+      /** Create a constant Char value */
+      def apply(x: Char): Constant
+      /** Match Char value constant and extract its value */
+      def unapply(constant: Constant): Option[Char]
+    }
+
+    /** Constant String value */
+    val String: ConstantStringModule
+
+    /** Constant String value */
+    trait ConstantStringModule { this: String.type =>
+      /** Create a constant String value */
+      def apply(x: String): Constant
+      /** Match String value constant and extract its value */
+      def unapply(constant: Constant): Option[String]
+    }
 
-    /** Module of ClassTag literals */
-    trait ClassTagModule { this: ClassTag.type =>
-      /** scala.reflect.ClassTag literal */
-      def apply[T](using x: Type): Constant
-      /** Extractor for ClassTag literals */
+    /** Constant Unit value */
+    val Unit: ConstantUnitModule
+
+    /** Constant Unit value */
+    trait ConstantUnitModule { this: Unit.type =>
+      /** Create a constant Unit value */
+      def apply(): Constant
+      /** Match Unit value constant */
+      def unapply(constant: Constant): Boolean
+    }
+
+    /** Constant null value */
+    val Null: ConstantNullModule
+
+    /** Constant null value */
+    trait ConstantNullModule { this: Null.type =>
+      /** Create a constant null value */
+      def apply(): Constant
+      /** Match null value constant */
+      def unapply(constant: Constant): Boolean
+    }
+
+    /** Constant class value representing a `classOf[T]` */
+    val ClassOf: ConstantClassOfModule
+
+    /** Constant class value representing a `classOf[T]` */
+    trait ConstantClassOfModule { this: ClassOf.type =>
+      /** Create a constant class value representing `classOf[<tpe>]` */
+      def apply(tpe: Type): Constant
+      /** Match a class value constant representing `classOf[<tpe>]` and extract its type */
       def unapply(constant: Constant): Option[Type]
     }
+
   }
 
   given ConstantMethods as ConstantMethods = ConstantMethodsImpl

compiler/src/dotty/tools/dotc/quoted/QuoteContextImpl.scala

@@ -165,19 +165,19 @@ class ExtractorsPrinter[R <: Reflection & Singleton](val tasty: R) extends Print
     }
 
     def visitConstant(x: Constant): Buffer = x match {
-      case Constant(()) => this += "Constant(())"
-      case Constant(null) => this += "Constant(null)"
-      case Constant(value: Boolean) => this += "Constant(" += value += ")"
-      case Constant(value: Byte) => this += "Constant(" += value += ": Byte)"
-      case Constant(value: Short) => this += "Constant(" += value += ": Short)"
-      case Constant(value: Char) => this += "Constant('" += value += "')"
-      case Constant(value: Int) => this += "Constant(" += value.toString += ")"
-      case Constant(value: Long) => this += "Constant(" += value += "L)"
-      case Constant(value: Float) => this += "Constant(" += value += "f)"
-      case Constant(value: Double) => this += "Constant(" += value += "d)"
-      case Constant(value: String) => this += "Constant(\"" += value += "\")"
-      case Constant.ClassTag(value) =>
-        this += "Constant.ClassTag("
+      case Constant.Unit() => this += "Constant.Unit()"
+      case Constant.Null() => this += "Constant.Null()"
+      case Constant.Boolean(value) => this += "Constant.Boolean(" += value += ")"
+      case Constant.Byte(value) => this += "Constant.Byte(" += value += ")"
+      case Constant.Short(value) => this += "Constant.Short(" += value += ")"
+      case Constant.Int(value) => this += "Constant.Int(" += value += ")"
+      case Constant.Long(value) => this += "Constant.Long(" += value += "L)"
+      case Constant.Float(value) => this += "Constant.Float(" += value += "f)"
+      case Constant.Double(value) => this += "Constant.Double(" += value += "d)"
+      case Constant.Char(value) => this += "Constant.Char('" += value += "')"
+      case Constant.String(value) => this += "Constant.String(\"" += value += "\")"
+      case Constant.ClassOf(value) =>
+        this += "Constant.ClassOf("
         visitType(value) += ")"
     }