Merge pull request #6747 from dotty-staging/add-quoted-expr-block

Add quoted.Expr.block

Author: nicolasstucki

library/src-3.x/scala/quoted/Expr.scala

@@ -37,6 +37,15 @@ package quoted {
         tg.untupled(args => new FunctionAppliedTo[R](f, args.toArray.map(_.asInstanceOf[Expr[_]])))
     }
 
+    /** Returns A expression containing a block with the given statements and ending with the expresion
+     *  Given list of statements `s1 :: s2 :: ... :: Nil` and an expression `e` the resulting expression
+     *  will be equivalent to `'{ $s1; $s2; ...; $e }`.
+     */
+    def block[T](statements: List[Expr[_]], expr: Expr[T])(implicit refl: tasty.Reflection): Expr[T] = {
+      import refl._
+      Block(statements.map(_.unseal), expr.unseal).seal.asInstanceOf[Expr[T]]
+    }
+
   }
 
 }

tests/run-macros/quoted-expr-block/quoted_1.scala

@@ -0,0 +1,10 @@
+import scala.quoted._
+
+inline def replicate(inline times: Int, code: => Any) = ${replicateImpl(times, 'code)}
+
+private def replicateImpl(times: Int, code: Expr[Any]) given tasty.Reflection = {
+  @annotation.tailrec def loop(n: Int, accum: List[Expr[Any]]): List[Expr[Any]] =
+    if (n > 0) loop(n - 1, code :: accum) else accum
+  Expr.block(loop(times, Nil), '{})
+
+}

tests/run-macros/quoted-expr-block/quoted_2.scala

@@ -0,0 +1,8 @@
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    var a = 0
+    replicate(500, a += 1)
+    assert(a == 500, a)
+  }
+}