Add canBuildFrom for arrays of value classes

Author: VladimirNik

src/dotty/DottyPredef.scala

@@ -1,8 +1,9 @@
 package dotty
 
+import scala.collection.generic.CanBuildFrom
 import scala.reflect.runtime.universe.TypeTag
 import scala.reflect.ClassTag
-import scala.collection.mutable.{ArrayOps, WrappedArray}
+import scala.collection.mutable.{ArrayBuilder, ArrayOps, WrappedArray}
 import dotty.runtime.vc._
 import scala.Predef.???
 
@@ -47,4 +48,19 @@ object DottyPredef {
     case x: Array[Unit] => scala.Predef.unitArrayOps(x)
     case null => null
   }).asInstanceOf[ArrayOps[T]]
+
+  implicit def canBuildFrom2[T](implicit t: ClassTag[T]): CanBuildFrom[Array[_], T, Array[T]] = {
+    t match {
+      case _: VCIntCompanion[_] | _: VCShortCompanion[_] |
+           _: VCLongCompanion[_] | _: VCByteCompanion[_] |
+           _: VCBooleanCompanion[_] | _: VCCharCompanion[_] |
+           _: VCFloatCompanion[_] | _: VCDoubleCompanion[_] |
+           _: VCObjectCompanion[_] =>
+        new CanBuildFrom[Array[_], T, Array[T]] {
+          def apply(from: Array[_]) = new VCArrayBuilder[T]()(t).asInstanceOf[ArrayBuilder[T]]
+          def apply() = new VCArrayBuilder[T]()(t).asInstanceOf[ArrayBuilder[T]]
+        }
+      case _ => scala.Array.canBuildFrom[T](t)
+    }
+  }
 }

test/dotc/tests.scala

@@ -106,6 +106,7 @@ class tests extends CompilerTest {
   @Test def pos_companions = compileFile(posDir, "companions", twice)
   @Test def pos_vc_proto_any_val = compileFile(vcArraysDir, "prototypeAnyVal", args = "-Ycheck:all" :: Nil)
   @Test def pos_vc_array_functions = compileFile(runDir, "valueclasses-array-functions", args = "-Ycheck:all" :: Nil)
+  @Test def pos_vc_array_functions2 = compileFile(runDir, "valueclasses-array-functions2", args = "-Ycheck:all" :: Nil)
   @Test def pos_vc_array_usage = compileFile(runDir, "valueclasses-array-usage", args = "-Ycheck:all" :: Nil)
   @Test def pos_vc_array_gen = compileFile(runDir, "valueclasses-array-gen", args = "-Ycheck:all" :: Nil)
   @Test def pos_vc_array_int = compileFile(runDir, "valueclasses-array-int", args = "-Ycheck:all" :: Nil)

tests/run/valueclasses-array-functions2.check

@@ -0,0 +1,6 @@
+r: Set(X(6), X(8), X(10))
+r3: Set(X(1), X(2), X(3))
+r4: Set(X(1), X(2), X(3))
+r5: Set(X(3), X(6), X(9))
+r6: Set(Z(1), Z(2), Z(3))
+v7: Set(Z(X(3)), Z(X(4)), Z(X(5)))

tests/run/valueclasses-array-functions2.scala

@@ -0,0 +1,27 @@
+class X(val x: Int) extends AnyVal {
+  override def toString = s"X($x)"
+}
+class Y(val y: Int)
+class Z(val z: String) extends AnyVal {
+  override def toString = s"Z($z)"
+}
+
+object Test {
+  def main(args: Array[String]) = {
+    val r = test map { v1 => new X(v1.x*2) }
+    println(s"r: ${r.toSet}")
+    val r3 = Array(1,2,3).map(v3 => new X(v3))
+    println(s"r3: ${r3.toSet}")
+    val r4 = test2 map (v4 => new X(v4.y))
+    println(s"r4: ${r4.toSet}")
+    val r5 = test3 map {x => new X(x.asInstanceOf[X].x*3)}
+    println(s"r5: ${r5.toSet}")
+    val r6 = test2 map (v6 => new Z(v6.y.toString))
+    println(s"r6: ${r6.toSet}")
+    val r7 = test map (v7 => new Z(v7.toString))
+    println(s"v7: ${r7.toSet}")
+  }
+  def test = Array(new X(3), new X(4), new X(5))
+  def test2 = Array(new Y(1), new Y(2), new Y(3))
+  def test3: Array[_] = Array(new X(1), new X(2), new X(3))
+}