Type stealer that allows to steal types after typer

Proposed to be used from repl: it gives you internal
representation of types after frontend and a context to play with them

Author: DarkDimius

test/test/DottyTypeStealer.scala

@@ -0,0 +1,32 @@
+package test
+
+import dotty.tools.dotc.ast.tpd
+import dotty.tools.dotc.core.Names._
+import dotty.tools.dotc.ast.tpd._
+import dotty.tools.dotc.core.Contexts.Context
+import dotty.tools.dotc.core.Decorators._
+import dotty.tools.dotc.core.Types.Type
+
+object DottyTypeStealer {
+  def stealType(source: String, typeStrings: String*): (Context, List[Type]) = {
+    val dummyName = "x_x_x"
+    val vals = typeStrings.zipWithIndex.map{case (s, x)=> s"val ${dummyName}$x: $s = ???"}.mkString("\n")
+    val gatheredSource = s" ${source}\n object A$dummyName {$vals}"
+    var scontext : Context = null
+    var tp: List[Type] = null
+    new DottyTest().checkCompile("frontend",gatheredSource) {
+      (tree, context) =>
+        implicit val ctx = context
+        val findValDef: (List[ValDef], tpd.Tree) => List[ValDef] =
+          (acc , tree) =>  { tree match {
+          case t: ValDef if t.name.startsWith(dummyName.toTermName) => t :: acc
+          case _ => acc
+        }
+      }
+      val d = new DeepFolder[List[ValDef]](findValDef).foldOver(Nil, tree)
+      tp = d.map(_.tpe.widen)
+      scontext = context
+    }
+    (scontext, tp)
+  }
+}