How to get Enumeration values back when using Scala parser combinators.

gistfile1.scala

// ISO 3166-1 alpha-2 two letter country codes from http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2  
object Country extends Enumeration {
  val Andorra = Value("ad") // Andorra
  val UAE = Value("ae") // United Arab Emirates
  val Afghanistan = Value("af") // Afghanistan
  // ...
}

trait CountryParser extends JavaTokenParsers {
  // would love to get rid of the silly regex
  lazy val country: Parser[Country.Value] = """\w+""".r ^? ({
    // if lower-cased
    case str if Country.values.exists((ctry) => ctry.toString == str) => Country.withName(str)
    // if upper-cased
    case str if Country.values.exists((ctry) => ctry.toString.toUpperCase == str) => Country.withName(str.toLowerCase)
  }, "Unknown country code: " + _)
}

It'd be awesome if someone could figure out a generic version. This is along the lines:

def enumParser[T <% Enumeration, V <% Enumeration#Value](enum: T): Parser[V] = """\w+""".r ^? ({
  // if lower-cased
  case str if enum.values.exists((value: V) => value.toString == str) => enum.withName(str)
  // if upper-cased
  case str if enum.values.exists((value: V) => value.toString.toUpperCase == str) => enum.withName(str.toLowerCase)
}, "Unknown code: " + _)

But it doesn't work:

[info] Compiling 1 Scala source to target/scala-2.9.1/classes...
amb prefix: _13.type#class ValueSet _9.type#class ValueSet
amb prefix: _13.type#class ValueSet _9.type#class ValueSet
amb prefix: _13.type#class ValueSet _9.type#class ValueSet
amb prefix: _13.type#class ValueSet _9.type#class ValueSet
[error] /Users/peter/Projects/Miogiro/Code/sms/src/main/scala/SMSParsers.scala:16: overloaded method value exists with alternatives:
[error]   (p: Enumeration#Value => Boolean)Boolean <and>
[error]   (p: Enumeration#Value => Boolean)Boolean <and>
[error]   (p: Enumeration#Value => Boolean)Boolean <and>
[error]   (pred: Enumeration#Value => Boolean)Boolean
[error]  cannot be applied to (V => Boolean)
[error]     case str if enum.values.exists((value: V) => value.toString == str) => enum.withName(str)
[error]                             ^
[error] one error found