Fix stdout redirect for REPL's println

When printing in the REPL via `println`, the output would end up on the
same line, since stdout had not been redirected. This commit remedies
that.

It also adds syntax highlighting to result types.

Author: felixmulder

src/dotty/tools/dotc/repl/CompilingInterpreter.scala

@@ -24,6 +24,7 @@ import dotty.tools.backend.jvm.GenBCode
 import Symbols._, Types._, Contexts._, StdNames._, Names._, NameOps._
 import Decorators._
 import scala.util.control.NonFatal
+import printing.SyntaxHighlighting
 
 /** An interpreter for Scala code which is based on the `dotc` compiler.
  *
@@ -210,11 +211,11 @@ class CompilingInterpreter(out: PrintWriter, ictx: Context) extends Compiler wit
         if (!req.compile())
           Interpreter.Error // an error happened during compilation, e.g. a type error
         else {
-          val (interpreterResultString, succeeded) = req.loadAndRun()
+          val (resultStrings, succeeded) = req.loadAndRun()
           if (delayOutput)
-            previousOutput = clean(interpreterResultString) :: previousOutput
+            previousOutput = resultStrings.map(clean) ::: previousOutput
           else if (printResults || !succeeded)
-            out.print(clean(interpreterResultString))
+            resultStrings.map(x => out.print(clean(x)))
           if (succeeded) {
             prevRequests += req
             Interpreter.Success
@@ -388,19 +389,31 @@ class CompilingInterpreter(out: PrintWriter, ictx: Context) extends Compiler wit
      *           a boolean indicating whether the run succeeded without throwing
      *           an exception.
      */
-    def loadAndRun(): (String, Boolean) = {
+    def loadAndRun(): (List[String], Boolean) = {
       val interpreterResultObject: Class[_] =
         Class.forName(resultObjectName, true, classLoader)
       val resultValMethod: java.lang.reflect.Method =
         interpreterResultObject.getMethod("result")
       try {
-        (resultValMethod.invoke(interpreterResultObject).toString, true)
+        val ps = new java.io.ByteArrayOutputStream()
+        Console.withOut(ps) {
+          val res = SyntaxHighlighting(resultValMethod.invoke(interpreterResultObject).toString).toArray
+          val prints = ps.toString("utf-8")
+          val printList =
+            if (prints == "") Nil
+            else prints :: Nil
+
+          if (!delayOutput)
+            out.print(prints)
+
+          (printList :+ new String(res), true)
+        }
       } catch {
         case NonFatal(ex) =>
           def cause(ex: Throwable): Throwable =
             if (ex.getCause eq null) ex else cause(ex.getCause)
           val orig = cause(ex)
-          (stringFrom(str => orig.printStackTrace(str)), false)
+          (stringFrom(str => orig.printStackTrace(str)) :: Nil, false)
       }
     }