Scala example source code file (CmdLineParser.scala)

This example Scala source code file (CmdLineParser.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

argsreader, flag, opt, opt, optmap, optval, optval, parser, parser, set, string, stropt, t, t

The Scala CmdLineParser.scala source code

/*-------------------------------------------------------------------------*\
**  ScalaCheck                                                             **
**  Copyright (c) 2007-2010 Rickard Nilsson. All rights reserved.          **
**  http://www.scalacheck.org                                              **
**                                                                         **
**  This software is released under the terms of the Revised BSD License.  **
**  There is NO WARRANTY. See the file LICENSE for the full text.          **
\*-------------------------------------------------------------------------*/

package org.scalacheck.util

import scala.util.parsing.combinator.Parsers
import scala.util.parsing.input.Reader
import scala.util.parsing.input.Position
import scala.collection.Set
import org.scalacheck.Test

trait CmdLineParser extends Parsers {

  type Elem = String

  trait Opt[+T] {
    val default: T
    val names: Set[String]
    val help: String
  }
  trait Flag extends Opt[Unit]
  trait IntOpt extends Opt[Int]
  trait StrOpt extends Opt[String]

  class OptMap {
    private val opts = new collection.mutable.HashMap[Opt[_], Any]
    def apply(flag: Flag): Boolean = opts.contains(flag)
    def apply[T](opt: Opt[T]): T = opts.get(opt) match {
      case None => opt.default
      case Some(v) => v.asInstanceOf[T]
    }
    def update[T](opt: Opt[T], optVal: T) = opts.update(opt, optVal)
  }

  val opts: Set[Opt[_]]

  private class ArgsReader(args: Array[String], i: Int) extends Reader[String] {
    val pos = new Position {
      val column = (args take i).foldLeft(1)(_ + _.length + 1)
      val line = 1
      val lineContents = args.mkString(" ")
    }
    val atEnd = i >= args.length
    def first = if(atEnd) null else args(i)
    def rest = if(atEnd) this else new ArgsReader(args, i+1)
  }

  private def getOpt(s: String) = {
    if(s == null || s.length == 0 || s.charAt(0) != '-') None
    else opts.find(_.names.contains(s.drop(1)))
  }

  private val opt: Parser[Opt[Any]] = accept("option name", {
    case s if getOpt(s).isDefined => getOpt(s).get
  })

  private val strVal: Parser[String] = accept("string", {
    case s if s != null => s
  })

  private val intVal: Parser[Int] = accept("integer", {
    case s if s != null && s.length > 0 && s.forall(_.isDigit) => s.toInt
  })

  private case class OptVal[T](o: Opt[T], v: T)

  private val optVal: Parser[OptVal[Any]] = opt into {
    case o: Flag => success(OptVal(o, ()))
    case o: IntOpt => intVal ^^ (v => OptVal(o, v))
    case o: StrOpt => strVal ^^ (v => OptVal(o, v))
  }

  val options: Parser[OptMap] = rep(optVal) ^^ { xs =>
    val map = new OptMap
    xs.foreach { case OptVal(o,v) => map(o) = v }
    map
  }

  def printHelp = {
    println("Available options:")
    opts.foreach { opt =>
      println("  " + opt.names.map("-"+_).mkString(", ") + ": " + opt.help)
    }
  }

  def parseArgs[T](args: Array[String])(f: OptMap => T) = 
    phrase(options map f)(new ArgsReader(args,0))
}