Scala example source code file (FastScalac.scala)

This example Scala source code file (FastScalac.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

ant, boolean, compilation, compiler, fscsettings, list, none, nsc, option, path, scalac, some, string

The FastScalac.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala Ant Tasks                      **
**    / __/ __// _ | / /  / _ |    (c) 2005-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

package scala.tools.ant

import org.apache.tools.ant.{AntClassLoader, Project}
import org.apache.tools.ant.taskdefs.Java
import org.apache.tools.ant.types.Path

import scala.tools.nsc.Settings
import scala.tools.nsc.io.File
import scala.tools.nsc.settings.FscSettings
import scala.tools.nsc.util.ScalaClassLoader

/** An Ant task to compile with the fast Scala compiler (`fsc`).
 *
 *  In addition to the attributes shared with the `Scalac` task, this task
 *  also accepts the following attributes:
 *  - `reset`
 *  - `server`
 *  - `shutdown`
 *  - `ipv4`
 *  - `maxIdle`
 *
 *  @author Stephane Micheloud
 */
class FastScalac extends Scalac {

  private var resetCaches: Boolean = false

  private var serverAddr: Option[String] = None

  private var shutdownServer: Boolean = false

  private var useIPv4: Boolean = false

  private var idleMinutes: Option[Int] = None

/*============================================================================*\
**                             Properties setters                             **
\*============================================================================*/

  /** Sets the `reset` attribute. Used by [[http://ant.apache.org Ant]].
   *
   *  @param input The value for `reset`.
   */
  def setReset(input: Boolean) { resetCaches = input }

  /** Sets the `server` attribute. Used by [[http://ant.apache.org Ant]].
   *
   *  @param input The value for `server`.
   */
  def setServer(input: String) { serverAddr = Some(input) }

  /** Sets the `shutdown` attribute. Used by [[http://ant.apache.org Ant]].
   *
   *  @param input The value for `shutdown`.
   */
  def setShutdown(input: Boolean) { shutdownServer = input }

  /** Sets the `ipv4` attribute. Used by [[http://ant.apache.org Ant]].
   *
   *  @param input The value for `ipv4`.
   */
  def setIPv4(input: Boolean) { useIPv4 = input }

  /** Sets the `maxIdle` attribute. Used by [[http://ant.apache.org Ant]].
   *
   *  @param input The value for `maxIdle`.
   */
  def setMaxIdle(input: Int) { if (0 <= input) idleMinutes = Some(input) }

/*============================================================================*\
**                             The execute method                             **
\*============================================================================*/

  override protected def newSettings(error: String=>Unit): Settings =
    new FscSettings(error)

  /** Performs the compilation. */
  override def execute() {
    val (settings, sourceFiles, javaOnly) = initialize
    if (sourceFiles.isEmpty || javaOnly)
      return

    // initialize fsc specific settings
    val s = settings.asInstanceOf[FscSettings] // safe (newSettings)
    s.reset.value = resetCaches
    if (!serverAddr.isEmpty) s.server.value = serverAddr.get
    s.shutdown.value = shutdownServer
    s.preferIPv4.value = useIPv4
    if (!idleMinutes.isEmpty) s.idleMins.value = idleMinutes.get

    val stringSettings =
      List(
        /*scalac*/
        s.bootclasspath, s.classpath, s.extdirs, s.dependencyfile, s.encoding,
        s.outdir, s.sourcepath,
        /*fsc*/
        s.server
      ) filter (_.value != "") flatMap (x => List(x.name, x.value))

    val choiceSettings =
      List(
        /*scalac*/
        s.debuginfo, s.target
      ) filter (x => x.value != x.default) map (x => "%s:%s".format(x.name, x.value))

    val booleanSettings =
      List(
        /*scalac*/
        s.debug, s.deprecation, s.explaintypes, s.nospecialization, s.nowarn,
        s.optimise, s.unchecked, s.usejavacp, s.verbose,
        /*fsc*/
        s.preferIPv4, s.reset, s.shutdown
      ) filter (_.value) map (_.name)

    val intSettings =
      List(
        /*fsc*/
        s.idleMins
      ) filter (x => x.value != x.default) flatMap (x => List(x.name, x.value.toString))

    val phaseSetting = {
      val s = settings.log
      if (s.value.isEmpty) Nil
      else List("%s:%s".format(s.name, s.value.mkString(",")))
    }

    val fscOptions =
      stringSettings ::: choiceSettings ::: booleanSettings ::: intSettings ::: phaseSetting

    val java = new Java(this)
    java setFork true
    // use same default memory options as in fsc script
    java.createJvmarg() setValue "-Xmx256M"
    java.createJvmarg() setValue "-Xms32M"
    val scalacPath: Path = {
      val path = new Path(getProject)
      if (compilerPath.isDefined) path add compilerPath.get
      else getClass.getClassLoader match {
        case cl: AntClassLoader =>
          path add new Path(getProject, cl.getClasspath)
        case _ =>
          buildError("Compilation failed because of an internal compiler error;"+
                     " see the error output for details.")
      }
      path
    }
    java.createJvmarg() setValue ("-Xbootclasspath/a:"+scalacPath)
    s.jvmargs.value foreach (java.createJvmarg() setValue _)

    val scalaHome: String = try {
      val url = ScalaClassLoader.originOfClass(classOf[FastScalac]).get
      File(url.getFile).jfile.getParentFile.getParentFile.getAbsolutePath
    } catch {
      case _: Throwable =>
        buildError("Compilation failed because of an internal compiler error;"+
                   " couldn't determine value for -Dscala.home=<value>")
    }
    java.createJvmarg() setValue "-Dscala.usejavacp=true"
    java.createJvmarg() setValue ("-Dscala.home="+scalaHome)
    s.defines.value foreach (java.createJvmarg() setValue _)

    java setClassname "scala.tools.nsc.MainGenericRunner"
    java.createArg() setValue "scala.tools.nsc.CompileClient"

    // Encode scalac/javac args for use in a file to be read back via "@file.txt"
    def encodeScalacArgsFile(t: Traversable[String]) = t map { s =>
      if(s.find(c => c <= ' ' || "\"'\\".contains(c)).isDefined)
        "\"" + s.flatMap(c => (if(c == '"' || c == '\\') "\\" else "") + c ) + "\""
      else s
    } mkString "\n"

    // dump the arguments to a file and do "java @file"
    val tempArgFile = File.makeTemp("fastscalac")
    val tokens = fscOptions ++ (sourceFiles map (_.getPath))
    tempArgFile writeAll encodeScalacArgsFile(tokens)

    val paths = List(Some(tempArgFile.toAbsolute.path), argfile).flatten map (_.toString)
    val res = execWithArgFiles(java, paths)

    if (failonerror && res != 0)
      buildError("Compilation failed because of an internal compiler error;"+
            " see the error output for details.")
  }
}