Allows you to look at sources of dependencies in ensime. Feel free to transform this into a sbt plugin.

ensimeWithSources.scala

  // After having run eclipse with-sources=true from sbt (with sbteclipse) .classpath should contain sourcepaths:
  val eclippseCp = scala.xml.XML.load(".classpath")
  val entries = eclippseCp.child filter { _.label == "classpathentry" }
  val sources = entries flatMap { _.attributes filter { _.key=="sourcepath" }} map { _.value.text }
  val destDir = "~/ensime-sources" // feel free to modify this

  def fileName(file: String) = new java.io.File(file).getName.replace("-sources.jar", "")

  import java.io.File

  def extractJar(file: File, destDir: String): Unit = {
    val jar = new java.util.jar.JarFile(file)

    import scala.collection.JavaConverters._
    val entries = jar.entries().asScala.toList.sortBy(_.getName.length)

    def withResource[A <: {def close(): Unit},B](res: A)(func: A=>B) = try func(res) finally res.close()

    for {
      entry <- entries
      destinationFile = new java.io.File(destDir + java.io.File.separator + entry.getName())
    } {
      if (entry.isDirectory()) { 
        println(s"dir: ${destinationFile}")
        destinationFile.mkdir()
      } else {
        println(s"file: ${destinationFile}")
        val parent = destinationFile.getParentFile
        if (!parent.exists) parent.mkdirs()
        destinationFile.createNewFile()
        withResource(jar.getInputStream(entry)) { is => 
          withResource(new java.io.FileOutputStream(destinationFile)) { fos =>
            while (is.available() > 0) {
              fos.write(is.read())
            }
          }
        }
      }
    }
  }
  // this will unpack the sources in the destDir 
  sources foreach { file => 
    extractJar(new File(file), destDir + fileName(file))
  }

  // this goes in .ensime file
  println(sources map { file =>
    s""""$destDir/${fileName(file)}""""
  } mkString(":reference-source-roots (\n", "\n", "\n)"))