Move quoted.Liftable to src-2.x and src-3.x

Author: nicolasstucki

library/src/scala/quoted/Liftable.scala renamed to library/src-2.x/scala/quoted/Liftable.scala

@@ -0,0 +1,59 @@
+package scala.quoted
+
+import scala.runtime.quoted.Unpickler.liftedExpr
+
+/** A typeclass for types that can be turned to `quoted.Expr[T]`
+ *  without going through an explicit `'{...}` operation.
+ */
+abstract class Liftable[T] {
+  def toExpr(x: T): Expr[T]
+}
+
+/** Some liftable base types. To be completed with at least all types
+ *  that are valid Scala literals. The actual implementation of these
+ *  typed could be in terms of `ast.tpd.Literal`; the test `quotable.scala`
+ *  gives an alternative implementation using just the basic staging system.
+ */
+object Liftable {
+
+  implicit def BooleanIsLiftable: Liftable[Boolean] = new Liftable[Boolean] {
+    def toExpr(x: Boolean): Expr[Boolean] = liftedExpr(x)
+  }
+
+  implicit def ByteIsLiftable: Liftable[Byte] = new Liftable[Byte] {
+    def toExpr(x: Byte): Expr[Byte] = liftedExpr(x)
+  }
+
+  implicit def CharIsLiftable: Liftable[Char] = new Liftable[Char] {
+    def toExpr(x: Char): Expr[Char] = liftedExpr(x)
+  }
+
+  implicit def ShortIsLiftable: Liftable[Short] = new Liftable[Short] {
+    def toExpr(x: Short): Expr[Short] = liftedExpr(x)
+  }
+
+  implicit def IntIsLiftable: Liftable[Int] = new Liftable[Int] {
+    def toExpr(x: Int): Expr[Int] = liftedExpr(x)
+  }
+
+  implicit def LongIsLiftable: Liftable[Long] = new Liftable[Long] {
+    def toExpr(x: Long): Expr[Long] = liftedExpr(x)
+  }
+
+  implicit def FloatIsLiftable: Liftable[Float] = new Liftable[Float] {
+    def toExpr(x: Float): Expr[Float] = liftedExpr(x)
+  }
+
+  implicit def DoubleIsLiftable: Liftable[Double] = new Liftable[Double] {
+    def toExpr(x: Double): Expr[Double] = liftedExpr(x)
+  }
+
+  implicit def StringIsLiftable: Liftable[String] = new Liftable[String] {
+    def toExpr(x: String): Expr[String] = liftedExpr(x)
+  }
+
+  implicit def ClassIsLiftable[T]: Liftable[Class[T]] = new Liftable[Class[T]] {
+    def toExpr(x: Class[T]): Expr[Class[T]] = liftedExpr(x)
+  }
+
+}