Scala example source code file (GenericRunnerCommand.scala)

This example Scala source code file (GenericRunnerCommand.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

asjar, asobject, asrepl, asscript, compiler, error, genericrunnercommand, howtorun, j, list, nsc, string

The GenericRunnerCommand.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2007-2013 LAMP/EPFL
 * @author  Lex Spoon
 */

package scala.tools.nsc

import GenericRunnerCommand._

/** A command for ScriptRunner */
class GenericRunnerCommand(
  args: List[String],
  override val settings: GenericRunnerSettings)
extends CompilerCommand(args, settings) {

  def this(args: List[String], error: String => Unit) =
    this(args, new GenericRunnerSettings(error))

  def this(args: List[String]) =
    this(args, str => Console.println("Error: " + str))

  /** name of the associated compiler command */
  override def cmdName = "scala"
  def compCmdName = "scalac"

  // change CompilerCommand behavior
  override def shouldProcessArguments: Boolean = false

  private lazy val (_ok, targetAndArguments) = settings.processArguments(args, processAll = false)
  override def ok = _ok
  private def guessHowToRun(target: String): GenericRunnerCommand.HowToRun = {
    if (!ok) Error
    else if (io.Jar.isJarOrZip(target)) AsJar
    else if (util.ScalaClassLoader.classExists(settings.classpathURLs, target)) AsObject
    else {
      val f = io.File(target)
      if (!f.hasExtension("class", "jar", "zip") && f.canRead) AsScript
      else {
        Console.err.println("No such file or class on classpath: " + target)
        Error
      }
    }
  }
  /** String with either the jar file, class name, or script file name. */
  def thingToRun = targetAndArguments.headOption getOrElse ""
  /** Arguments to thingToRun. */
  def arguments = targetAndArguments drop 1

  val howToRun = targetAndArguments match {
    case Nil      => AsRepl
    case hd :: _  => waysToRun find (_.name == settings.howtorun.value) getOrElse guessHowToRun(hd)
  }
  private def interpolate(s: String) = s.trim.replaceAll("@cmd@", cmdName).replaceAll("@compileCmd@", compCmdName) + "\n"

  def shortUsageMsg = interpolate("""
Usage: @cmd@ <options> [<script|class|object|jar> <arguments>]
   or  @cmd@ -help

All options to @compileCmd@ (see @compileCmd@ -help) are also allowed.
""")

  override def usageMsg = shortUsageMsg + interpolate("""
The first given argument other than options to @cmd@ designates
what to run.  Runnable targets are:

  - a file containing scala source
  - the name of a compiled class
  - a runnable jar file with a valid Main-Class attribute
  - or if no argument is given, the repl (interactive shell) is started

Options to @cmd@ which reach the java runtime:

 -Dname=prop  passed directly to java to set system properties
 -J<arg>      -J is stripped and <arg> passed to java as-is
 -nobootcp    do not put the scala jars on the boot classpath (slower)

Other startup options:

 -howtorun    what to run <script|object|jar|guess> (default: guess)
 -i <file>    preload <file> before starting the repl
 -e <string>  execute <string> as if entered in the repl
 -save        save the compiled script in a jar for future use
 -nc          no compilation daemon: do not use the fsc offline compiler

A file argument will be run as a scala script unless it contains only
self-contained compilation units (classes and objects) and exactly one
runnable main method.  In that case the file will be compiled and the
main method invoked.  This provides a bridge between scripts and standard
scala source.
  """) + "\n"
}

object GenericRunnerCommand {
  sealed abstract class HowToRun(val name: String) { }
  case object AsJar extends HowToRun("jar")
  case object AsObject extends HowToRun("object")
  case object AsScript extends HowToRun("script")
  case object AsRepl extends HowToRun("repl")
  case object Error extends HowToRun("<error>")
  val waysToRun = List(AsJar, AsObject, AsScript, AsRepl)
}