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import scala.language.implicitConversions
import scala.language.postfixOps
object Test extends App {
import scala.collection.{GenTraversableOnce,GenTraversableLike}
import scala.collection.generic._
def typed[T](t : => T) {}
def testTraversableLike = {
class FilterMapImpl[A, Repr](val r: GenTraversableLike[A, Repr]) /* extends AnyVal */ {
final def filterMap[B, That](f: A => Option[B])(implicit cbf: CanBuildFrom[Repr, B, That]): That =
r.flatMap(f(_).toSeq)
}
implicit def filterMap[Repr, A](r: Repr)(implicit fr: IsTraversableLike[Repr]): FilterMapImpl[fr.A,Repr] =
new FilterMapImpl[fr.A, Repr](fr.conversion(r))
val l = List(1, 2, 3, 4, 5)
val fml = l.filterMap(i => if(i % 2 == 0) Some(i) else None)
typed[List[Int]](fml)
println(fml)
val a = Array(1, 2, 3, 4, 5)
val fma = a.filterMap(i => if(i % 2 == 0) Some(i) else None)
typed[Array[Int]](fma)
println(fma.deep)
val s = "Hello World"
val fms1 = s.filterMap(c => if(c >= 'A' && c <= 'Z') Some(c) else None)
typed[String](fms1)
println(fms1)
val fms2 = s.filterMap(c =>if(c % 2 == 0) Some(c.toInt) else None)
typed[IndexedSeq[Int]](fms2)
println(fms2)
}
def testTraversableOnce = {
class FilterMapImpl[A, Repr](val r: GenTraversableOnce[A]) /* extends AnyVal */ {
final def filterMap[B, That](f: A => Option[B])(implicit cbf: CanBuildFrom[Repr, B, That]): That = {
val b = cbf()
for(e <- r.seq) f(e) foreach (b +=)
b.result
}
}
implicit def filterMap[Repr, A](r: Repr)(implicit fr: IsTraversableOnce[Repr]): FilterMapImpl[fr.A,Repr] =
new FilterMapImpl[fr.A, Repr](fr.conversion(r))
val l = List(1, 2, 3, 4, 5)
val fml = l.filterMap(i => if(i % 2 == 0) Some(i) else None)
typed[List[Int]](fml)
println(fml)
val a = Array(1, 2, 3, 4, 5)
val fma = a.filterMap(i => if(i % 2 == 0) Some(i) else None)
typed[Array[Int]](fma)
println(fma.deep)
val s = "Hello World"
val fms1 = s.filterMap(c => if(c >= 'A' && c <= 'Z') Some(c) else None)
typed[String](fms1)
println(fms1)
val fms2 = s.filterMap(c =>if(c % 2 == 0) Some(c.toInt) else None)
typed[IndexedSeq[Int]](fms2)
println(fms2)
}
testTraversableLike
testTraversableOnce
}
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