Scala example source code file (Reference.scala)

This example Scala source code file (Reference.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

collection, currently, list, listbuffer, map, maxline, mutable, reference, speccommandline, string, thiscommandline, unit

The Reference.scala Scala example source code

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

package scala.tools
package cmd

import scala.collection.mutable.ListBuffer
import nsc.Properties.envOrNone

/** Mixes in the specification trait and uses the vals therein to
 *  side-effect private accumulators.  From this emerges formatted help,
 *  lists of unary and binary arguments, an apply which can creates
 *  instances of the specification, and etc.
 *
 *  @see    Instance
 */
trait Reference extends Spec {
  lazy val options = new Reference.Accumulators()
  import options._

  def helpMsg     = options.helpMsg
  def propertyArgs: List[String] = Nil

  def isUnaryOption(s: String)  = unary contains fromOpt(s)
  def isBinaryOption(s: String) = binary contains fromOpt(s)
  def isExpandOption(s: String) = expansionMap contains fromOpt(s)

  def expandArg(arg: String): List[String] = expansionMap.getOrElse(fromOpt(arg), List(arg))

  protected def help(str: => String): Unit = addHelp(() => str)

  type ThisCommandLine <: CommandLine

  class SpecCommandLine(args: List[String]) extends CommandLine(Reference.this, args) { }
  protected def creator(args: List[String]): ThisCommandLine
  final def apply(args: String*): ThisCommandLine = creator(propertyArgs ++ args flatMap expandArg)

  type OptionMagic = Opt.Reference
  protected implicit def optionMagicAdditions(name: String) = new Opt.Reference(programInfo, options, name)
}

object Reference {
  val MaxLine = 80

  class Accumulators() {
    private val _help    = new ListBuffer[() => String]
    private var _unary   = List[String]()
    private var _binary  = List[String]()
    private var _expand  = Map[String, List[String]]()

    def helpFormatStr     = "    %-" + longestArg + "s %s"
    def defaultFormatStr  = (" " * (longestArg + 7)) + "%s"

    def addUnary(s: String): Unit  = _unary +:= s
    def addBinary(s: String): Unit = _binary +:= s

    def addExpand(opt: String, expanded: List[String]) =
      _expand += (opt -> expanded)

    def mapHelp(g: String => String): Unit = {
      val idx = _help.length - 1
      val f = _help(idx)

      _help(idx) = () => g(f())
    }

    def addHelp(f: () => String): Unit = _help += f
    def addHelpAlias(f: () => String) = mapHelp { s =>
      val str = "alias for '%s'" format f()
      def noHelp = (helpFormatStr.format("", "")).length == s.length
      val str2 = if (noHelp) str else " (" + str + ")"

      s + str2
    }
    def addHelpDefault(f: () => String): Unit = mapHelp { s =>
      val str = "(default: %s)" format f()

      if (s.length + str.length < MaxLine) s + " " + str
      else defaultFormatStr.format(s, str)
    }
    def addHelpEnvDefault(name: String): Unit = mapHelp { s =>
      val line1     = "%s (default: %s)".format(s, name)
      val envNow    = envOrNone(name) map ("'" + _ + "'") getOrElse "unset"
      val line2     = defaultFormatStr.format("Currently " + envNow)

      line1 + "\n" + line2
    }

    lazy val unary          = (_unary ++ _expand.keys).distinct
    lazy val binary         = _binary.distinct
    lazy val all            = unary ++ binary
    lazy val expansionMap   = _expand
    lazy val helpMsg        = _help map (f => f() + "\n") mkString
    lazy val longestArg     = all map (_.length) max
  }
}