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package dotty
import scala.annotation.implicitNotFound
@implicitNotFound("No member of type class Show could be found for ${T}")
trait Show[-T] {
def show(t: T): String
}
object Show {
private[this] val defaultShow = new Show[Any] {
def show(x: Any) = x.toString
}
implicit class ShowValue[V](val v: V) extends AnyVal {
def show(implicit ev: Show[V] = defaultShow): String =
ev.show(v)
}
implicit val stringShow = new Show[String] {
// From 2.12 spec:
//
// charEscapeSeq ::= ‘\‘ (‘b‘ | ‘t‘ | ‘n‘ | ‘f‘ | ‘r‘ | ‘"‘ | ‘'‘ | ‘\‘)
def show(str: String) =
"\"" + {
val sb = new StringBuilder
str.foreach {
case '\b' => sb.append("\\b")
case '\t' => sb.append("\\t")
case '\n' => sb.append("\\n")
case '\f' => sb.append("\\f")
case '\r' => sb.append("\\r")
case '\'' => sb.append("\\'")
case '\"' => sb.append("\\\"")
case c => sb.append(c)
}
sb.toString
} + "\""
}
implicit val intShow = new Show[Int] {
def show(i: Int) = i.toString
}
implicit val floatShow = new Show[Float] {
def show(f: Float) = f + "f"
}
implicit val doubleShow = new Show[Double] {
def show(d: Double) = d.toString
}
implicit val charShow = new Show[Char] {
def show(c: Char) = "'" + (c match {
case '\b' => "\\b"
case '\t' => "\\t"
case '\n' => "\\n"
case '\f' => "\\f"
case '\r' => "\\r"
case '\'' => "\\'"
case '\"' => "\\\""
case c => c
}) + "'"
}
implicit def showList[T](implicit st: Show[T]) = new Show[List[T]] {
def show(xs: List[T]) =
if (xs.isEmpty) "Nil"
else "List(" + xs.map(_.show).mkString(", ") + ")"
}
implicit val showNil = new Show[List[Nothing]] {
def show(xs: List[Nothing]) = "Nil"
}
implicit def showOption[T](implicit st: Show[T]) = new Show[Option[T]] {
def show(ot: Option[T]): String = ot match {
case Some(t) => "Some("+ st.show(t) + ")"
case none => "None"
}
}
implicit val showNone = new Show[Option[Nothing]] {
def show(n: Option[Nothing]) = "None"
}
implicit def showMap[K, V](implicit sk: Show[K], sv: Show[V]) = new Show[Map[K, V]] {
def show(m: Map[K, V]) =
"Map(" + m.map { case (k, v) => sk.show(k) + " -> " + sv.show(v) } .mkString (", ") + ")"
}
implicit def showMapOfNothing = new Show[Map[Nothing, Nothing]] {
def show(m: Map[Nothing, Nothing]) = m.toString
}
}
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