Implement getClass method

4 files changed, 117 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/Compiler.scala b/src/dotty/tools/dotc/Compiler.scala
index 75b790861..a58ee907d 100644
--- a/src/dotty/tools/dotc/Compiler.scala
+++ b/src/dotty/tools/dotc/Compiler.scala
@@ -62,6 +62,7 @@ class Compiler {
            new AugmentScala2Traits,
            new ResolveSuper),
       List(new Erasure),
+      List(new GetClass), // getClass transformation should be applied to specialized methods
       List(new ElimErasedValueType,
            new VCElideAllocations,
            new Mixin,
diff --git a/src/dotty/tools/dotc/transform/GetClass.scala b/src/dotty/tools/dotc/transform/GetClass.scala
new file mode 100644
index 000000000..0545133da
--- /dev/null
+++ b/src/dotty/tools/dotc/transform/GetClass.scala
@@ -0,0 +1,49 @@
+package dotty.tools.dotc
+package transform
+
+import ast.tpd
+import core.Contexts.Context
+import core.StdNames.nme
+import core.Symbols.TermSymbol
+import core.Phases.Phase
+import TreeTransforms.{MiniPhaseTransform, TransformerInfo}
+
+/** Rewrite `getClass` calls as follow:
+  *
+  *  For every instance of primitive class C whose boxed class is called B:
+  *    instanceC.getClass    -> B.TYPE
+  *  For every instance of non-primitive class D:
+  *    instanceD.getClass    -> instanceD.getClass
+  */
+class GetClass extends MiniPhaseTransform {
+  import tpd._
+
+  override def phaseName: String = "getClass"
+
+  override def runsAfter: Set[Class[_ <: Phase]] = Set(classOf[Erasure])
+
+  override def transformApply(tree: Apply)(implicit ctx: Context, info: TransformerInfo): Tree = {
+    import ast.Trees._
+
+    tree match {
+      case Apply(Select(qual, nme.getClass_), Nil) =>
+        val defn = ctx.definitions
+        val claz = qual.tpe.classSymbol
+
+        def TYPE(module: TermSymbol) = ref(module).select(nme.TYPE_).ensureConforms(tree.tpe)
+        claz match {
+          case defn.BooleanClass => TYPE(defn.BoxedBooleanModule)
+          case defn.ByteClass    => TYPE(defn.BoxedByteModule)
+          case defn.ShortClass   => TYPE(defn.BoxedShortModule)
+          case defn.CharClass    => TYPE(defn.BoxedCharModule)
+          case defn.IntClass     => TYPE(defn.BoxedIntModule)
+          case defn.LongClass    => TYPE(defn.BoxedLongModule)
+          case defn.FloatClass   => TYPE(defn.BoxedFloatModule)
+          case defn.DoubleClass  => TYPE(defn.BoxedDoubleModule)
+          case defn.UnitClass    => TYPE(defn.BoxedVoidModule)
+          case _                 => tree
+        }
+      case _ => tree
+    }
+  }
+}
diff --git a/tests/run/getclass.check b/tests/run/getclass.check
new file mode 100644
index 000000000..9d88762f4
--- /dev/null
+++ b/tests/run/getclass.check
@@ -0,0 +1,26 @@
+Value types:
+void
+boolean
+byte
+short
+char
+int
+long
+float
+double
+
+Class types:
+class SomeClass
+class ValueClass
+class scala.collection.immutable.$colon$colon
+class scala.Tuple2
+
+Arrays:
+class [Lscala.runtime.BoxedUnit;
+class [I
+class [D
+class [Lscala.collection.immutable.List;
+
+Functions:
+class Test$$$Lambda$1
+class Test$$$Lambda$2
diff --git a/tests/run/getclass.scala b/tests/run/getclass.scala
new file mode 100644
index 000000000..7e6430a53
--- /dev/null
+++ b/tests/run/getclass.scala
@@ -0,0 +1,41 @@
+class ValueClass(val i: Integer) extends AnyVal
+class SomeClass
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val cls: Predef.Class[_] = new SomeClass().getClass
+    val valCls: Predef.Class[_] = new ValueClass(1).getClass
+    val iCls: Class[Int] = 1.getClass
+    val f1: Function2[Int, Int, Unit] = (a: Int, b: Int) => println(a + b)
+    val f2: Function1[Int, Boolean] = (a: Int) => a % 2 == 0
+
+    println("Value types:")
+    println(().getClass)
+    println(true.getClass)
+    println(1.asInstanceOf[Byte].getClass)
+    println(1.asInstanceOf[Short].getClass)
+    println('a'.getClass)
+    println(1.getClass)
+    println(1L.getClass)
+    println(1f.getClass)
+    println(1d.getClass)
+
+    println("\nClass types:")
+    println(new SomeClass().getClass)
+    println(new ValueClass(1).getClass)
+    println(List(Array(1f)).getClass)
+    println(("a", Map(1 -> "b")).getClass)
+
+    println("\nArrays:")
+    println(Array(()).getClass)
+    println(Array(1).getClass)
+    println(Array(1d).getClass)
+    println(Array(List("1")).getClass)
+
+    println("\nFunctions:")
+    // FunctionN.getClass.toString has form of "class Test$$$Lambda$N/1349414238",
+    // but number (1349414238) depends on environment
+    println(f1.getClass.toString.takeWhile(_ != '/'))
+    println(f2.getClass.toString.takeWhile(_ != '/'))
+  }
+}