gistfile1.txt

  trait CanWhere[A] {
    def apply(f: PartialFunction[A, A]): Selector[Node]
  }
  
  implicit val stringToCanWhere = new CanWhere[String] {
    def apply(f: PartialFunction[String, String]) =
      Selector({ case Elem(p, name, a, s, c) if f.isDefinedAt(name) => Elem(p, f(name), a, s, c) })
  }
  
  implicit val nodeToCanWhere = new CanWhere[Node] {
    def apply(f: PartialFunction[Node, Node]) =
      Selector({ case e: Elem if f.isDefinedAt(e) => f(e) })
  }
  
  /**
   * Converts [[PartialFunction]]`[A, A]` into an instance of [[com.codecommit.antixml.Selector]]
   * which can then be passed to the appropriate methods on [[com.codecommit.antixml.Group]].
   * For example: `ns \ where { case "name" => "alternative" }`
   */
  def where[A: CanWhere](f: PartialFunction[A, A]): Selector[Node] = implicitly[CanWhere[A]].apply(f)