Scala example source code file (Property.scala)

This example Scala source code file (Property.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

file, list, nil, properties, property, propertymapper, reference, runnername, some, string

The Property.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2005-2013 LAMP/EPFL
 * @author  Paul Phillips
 */

package scala.tools
package cmd

import nsc.io._
import java.util.Properties
import java.io.FileInputStream

/** Contains logic for translating a property key/value pair into
 *  equivalent command line arguments.  The default settings will
 *  translate, given programInfo.runner == "foo" :
 *
 *    foo.bar=true  to  --bar       // if --bar is unary
 *    foo.bar=quux  to  --bar quux  // if --bar is binary
 */
class PropertyMapper(reference: Reference) extends (((String, String)) => List[String]) {
  import reference._
  lazy val RunnerName = programInfo.runner

  // e.g. "partest.shootout" -> "--shootout"
  def propNameToOptionName(key: String): Option[String] = (key split '.').toList match {
    case List(RunnerName, name) => Some(name)
    case _                      => None
  }

  def isPassThrough(key: String): Boolean = false                 // e.g. "partest.options"
  def onError(key: String, value: String): Unit = ()              // called when translate fails

  def translate(key: String, value: String): List[String] = {
    val opt = toOpt(key)

    if (isUnaryOption(key) && isTrue(value)) List(opt)
    else if (isBinaryOption(key)) List(opt, value)
    else returning(Nil)(_ => onError(key, value))
  }
  def isTrue(value: String) = List("yes", "on", "true") contains value.toLowerCase

  def apply(kv: (String, String)): List[String] = {
    val (k, v) = kv

    if (isPassThrough(k)) toArgs(v)
    else propNameToOptionName(k) match {
      case Some(optName)  => translate(optName, v)
      case _              => Nil
    }
  }
}

trait Property extends Reference {
  def propMapper: PropertyMapper
  override def propertyArgs: List[String] = systemPropertiesToOptions

  def loadProperties(file: File): Properties  =
    returning(new Properties)(_ load new FileInputStream(file.path))

  def systemPropertiesToOptions: List[String] =
    propertiesToOptions(System.getProperties)

  def propertiesToOptions(file: File): List[String] =
    propertiesToOptions(loadProperties(file))

  def propertiesToOptions(props: java.util.Properties): List[String] = {
    import scala.collection.JavaConversions._
    propertiesToOptions(props.toList)
  }
  def propertiesToOptions(props: List[(String, String)]) = props flatMap propMapper
}