Scala example source code file (ScalacFork.scala)

This example Scala source code file (ScalacFork.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

boolean, compilation, compiler, file, globpatternmapper, mandatory, none, nsc, option, scalacshared, some, string

The ScalacFork.scala Scala example source code

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

package scala
package tools.ant
package sabbus

import java.io.{ File, FileWriter }
import org.apache.tools.ant.Project
import org.apache.tools.ant.taskdefs.Java
import org.apache.tools.ant.util.{ GlobPatternMapper, SourceFileScanner }
import org.apache.tools.ant.BuildException
import scala.tools.nsc.io
import scala.tools.nsc.util.ScalaClassLoader

/** An Ant task to compile with the new Scala compiler (NSC).
 *
 *  This task can take the following parameters as attributes:
 *  - `srcdir` (mandatory),
 *  - `failonerror`,
 *  - `timeout`,
 *  - `jvmargs`,
 *  - `argfile`,
 *  - `params`.
 *
 *  It also takes the following parameters as nested elements:
 *  - `src` (for `srcdir`),
 *  - `classpath`,
 *  - `sourcepath`,
 *  - `bootclasspath`,
 *  - `extdirs`,
 *  - `compilerarg`.
 *
 *  @author Gilles Dubochet
 */
class ScalacFork extends ScalaMatchingTask with ScalacShared with TaskArgs {

  private def originOfThis: String =
    ScalaClassLoader.originOfClass(classOf[ScalacFork]) map (_.toString) getOrElse "<unknown>"

  /** Sets the `srcdir` attribute. Used by [[http://ant.apache.org Ant]].
   *  @param input The value of `sourceDir`. */
  def setSrcdir(input: File) {
    sourceDir = Some(input)
  }

  /** Sets the `failonerror` attribute. Used by [[http://ant.apache.org Ant]].
   *  @param input The value of `failOnError`. */
  def setFailOnError(input: Boolean) {
    failOnError = input
  }

  /** Sets the `timeout` attribute. Used by [[http://ant.apache.org Ant]].
   *  @param input The value of `timeout`. */
  def setTimeout(input: Long) {
    timeout = Some(input)
  }

  /** Sets the `jvmargs` attribute. Used by [[http://ant.apache.org Ant]].
   *  @param input The value of `jvmArgs`. */
  def setJvmArgs(input: String) {
    jvmArgs = Some(input)
  }

  /** Sets the `argfile` attribute. Used by [[http://ant.apache.org Ant]].
   *  @param input The value of `argfile`. */
  def setArgfile(input: File) {
    argfile = Some(input)
  }

  private var sourceDir: Option[File] = None
  private var failOnError: Boolean = true
  private var timeout: Option[Long] = None
  private var jvmArgs: Option[String] = None
  private var argfile: Option[File] = None

  private def createMapper() = {
    val mapper = new GlobPatternMapper()
    val extension = "*.class"
    mapper setTo extension
    mapper setFrom "*.scala"

    mapper
  }

  override def execute() {
    def plural(x: Int) = if (x > 1) "s" else ""

    log("Executing ant task scalacfork, origin: %s".format(originOfThis), Project.MSG_VERBOSE)

    val compilerPath = this.compilerPath getOrElse sys.error("Mandatory attribute 'compilerpath' is not set.")
    val sourceDir = this.sourceDir getOrElse sys.error("Mandatory attribute 'srcdir' is not set.")
    val destinationDir = this.destinationDir getOrElse sys.error("Mandatory attribute 'destdir' is not set.")

    val settings = new Settings
    settings.d = destinationDir

    compTarget foreach (settings.target = _)
    compilationPath foreach (settings.classpath = _)
    sourcePath foreach (settings.sourcepath = _)
    settings.extraParams = extraArgsFlat

    val mapper = createMapper()

    val includedFiles: Array[File] =
      new SourceFileScanner(this).restrict(
        getDirectoryScanner(sourceDir).getIncludedFiles,
        sourceDir,
        destinationDir,
        mapper
      ) map (x => new File(sourceDir, x))

    /* Nothing to do. */
    if (includedFiles.isEmpty && argfile.isEmpty)
      return

    if (includedFiles.nonEmpty)
      log("Compiling %d file%s to %s".format(includedFiles.length, plural(includedFiles.length), destinationDir))

    argfile foreach (x => log("Using argfile file: @" + x))

    val java = new Java(this)  // set this as owner
    java setFork true
    // using 'setLine' creates multiple arguments out of a space-separated string
    jvmArgs foreach (java.createJvmarg() setLine _)
    timeout foreach (java setTimeout _)

    java setClasspath compilerPath
    java setClassname MainClass

    // 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 = io.File.makeTemp("scalacfork")
    val tokens = settings.toArgs ++ (includedFiles 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)
      throw new BuildException("Compilation failed because of an internal compiler error;"+
            " see the error output for details.")
  }
}