Decompile [do] while loops

Author: nicolasstucki

compiler/src/dotty/tools/dotc/printing/DecompilerPrinter.scala

@@ -7,6 +7,7 @@ import dotty.tools.dotc.printing.Texts._
 import dotty.tools.dotc.core.Contexts._
 import dotty.tools.dotc.core.Flags._
 import dotty.tools.dotc.core.Symbols._
+import dotty.tools.dotc.core.StdNames._
 
 import scala.language.implicitConversions
 
@@ -16,7 +17,13 @@ class DecompilerPrinter(_ctx: Context) extends RefinedPrinter(_ctx) {
     annots.filter(_.tpe != defn.SourceFileAnnotType)
 
   override protected def blockText[T >: Untyped](trees: List[Trees.Tree[T]]): Text = {
-    super.blockText(trees.filterNot(_.isInstanceOf[Closure[_]]))
+    trees match {
+      case DefDef(_, _, _, _, Trees.If(cond, Trees.Block(body :: Nil, _), _)) :: y :: Nil if y.symbol.name == nme.WHILE_PREFIX =>
+        keywordText("while") ~ " (" ~ toText(cond) ~ ")" ~ toText(body)
+      case DefDef(_, _, _, _, Trees.Block(body :: Nil, Trees.If(cond, _, _))) :: y :: Nil if y.symbol.name == nme.DO_WHILE_PREFIX =>
+        keywordText("do") ~ toText(body) ~ keywordText("while") ~ " (" ~ toText(cond) ~ ")"
+      case _ => super.blockText(trees.filterNot(_.isInstanceOf[Closure[_]]))
+    }
   }
 
   override protected def packageDefText(tree: PackageDef): Text = {

tests/pos/simpleDoWhile.decompiled

@@ -0,0 +1,17 @@
+================================================================================
+out/posTestFromTasty/pos/simpleDoWhile/Foo.class
+--------------------------------------------------------------------------------
+package <empty> {
+  class Foo() extends Object() {
+    def foo: Unit =
+      {
+        var i: Int = 1
+        do
+          {
+            i = 0
+          }
+        while (i.!=(0))
+      }
+  }
+}
+--------------------------------------------------------------------------------

tests/pos/simpleDoWhile.scala

@@ -0,0 +1,8 @@
+class Foo {
+  def foo = {
+    var i = 1
+    do {
+      i = 0
+    } while (i != 0)
+  }
+}

tests/pos/simpleWhile.decompiled

@@ -0,0 +1,16 @@
+================================================================================
+out/posTestFromTasty/pos/simpleWhile/Foo.class
+--------------------------------------------------------------------------------
+package <empty> {
+  class Foo() extends Object() {
+    def foo: Unit =
+      {
+        var i: Int = 1
+        while (i.!=(0))
+          {
+            i = 0
+          }
+      }
+  }
+}
+--------------------------------------------------------------------------------

tests/pos/simpleWhile.scala

@@ -0,0 +1,8 @@
+class Foo {
+  def foo = {
+    var i = 1
+    while (i != 0) {
+      i = 0
+    }
+  }
+}