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/* NSC -- new Scala compiler
* Copyright 2005-2013 LAMP/EPFL
* @author Paul Phillips
package cmd
import{ File, Directory }
import scala.reflect.runtime.{universe => ru}
/** A general mechanism for defining how a command line argument
* (always a String) is transformed into an arbitrary type. A few
* example instances are in the companion object, but in general
* either IntFromString will suffice or you'll want custom transformers.
abstract class FromString[+T](implicit t: ru.TypeTag[T]) extends PartialFunction[String, T] {
def apply(s: String): T
def isDefinedAt(s: String): Boolean = true
def zero: T = apply("")
def targetString: String = t.toString
object FromString {
// We need this because we clash with the String => Path implicits.
private def toDir(s: String) = new Directory(new
/** Path related stringifiers.
val ExistingDir: FromString[Directory] = new FromString[Directory]()(tagOfDirectory) {
override def isDefinedAt(s: String) = toDir(s).isDirectory
def apply(s: String): Directory =
if (isDefinedAt(s)) toDir(s)
else cmd.runAndExit(println("'%s' is not an existing directory." format s))
def ExistingDirRelativeTo(root: Directory) = new FromString[Directory]()(tagOfDirectory) {
private def resolve(s: String) = (toDir(s) toAbsoluteWithRoot root).toDirectory
override def isDefinedAt(s: String) = resolve(s).isDirectory
def apply(s: String): Directory =
if (isDefinedAt(s)) resolve(s)
else cmd.runAndExit(println("'%s' is not an existing directory." format resolve(s)))
/** Argument expander, i.e. turns single argument "foo bar baz" into argument
* list "foo", "bar", "baz".
val ArgumentsFromString: FromString[List[String]] = new FromString[List[String]]()(tagOfListOfString) {
def apply(s: String) = toArgs(s)
/** Identity.
implicit val StringFromString: FromString[String] = new FromString[String]()(tagOfString) {
def apply(s: String): String = s
/** Implicit as the most likely to be useful as-is.
implicit val IntFromString: FromString[Int] = new FromString[Int]()(tagOfInt) {
override def isDefinedAt(s: String) = safeToInt(s).isDefined
def apply(s: String) = safeToInt(s).get
def safeToInt(s: String): Option[Int] = try Some(java.lang.Integer.parseInt(s)) catch { case _: NumberFormatException => None }
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