Make run run classfiles similar to dotr

Author: felixmulder

project/Build.scala

@@ -77,6 +77,7 @@ object DottyBuild extends Build {
     dependsOn(`dotty-library`).
     dependsOn(`dotty-interfaces`).
     settings(
+      addCommandAlias("run", "dotty-compiler/run") ++
       addCommandAlias("dotc", "dotty-compiler/dotc") ++
       addCommandAlias("repl", "dotty-compiler/repl") ++
       addCommandAlias(
@@ -180,6 +181,28 @@ object DottyBuild extends Build {
         )
       }.evaluated,
 
+      // Override run to be able to run compiled classfiles
+      run := {
+        val args: Seq[String] = spaceDelimited("<arg>").parsed
+        val java: String = Process("which" :: "java" :: Nil) !!
+        val scalaLib = (dependencyClasspath in Runtime, packageAll)
+          .map { (attList, _) =>
+            attList
+              .map(_.data.getAbsolutePath)
+              .find(_.contains("scala-library"))
+              .toList.mkString(":")
+          }.value
+
+        if (java == "")
+          println("Couldn't find java executable on path, please install java to a default location")
+        else if (scalaLib == "") {
+          println("Couldn't find scala-library on classpath, please run using script in bin dir instead")
+        } else {
+          val dottyLib = packageAll.value("dotty-library")
+          s"""$java -classpath .:$dottyLib:$scalaLib ${args.mkString(" ")}""" !
+        }
+      },
+
       // Set run baseDir to be root of project, makes dotc saner
       baseDirectory in run := baseDirectory.value / "..",
       dotc := Def.inputTaskDyn {