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import collection._
import collection.generic._
object Test {
def collectIDA[A, B, Repr, That](_this: TraversableLike[A, Repr])(pf: PartialFunction[A, B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
val repr: Repr = _this.asInstanceOf[Repr]
val b = bf(repr)
_this foreach { x => if (pf isDefinedAt x) b += pf(x) }
b.result
}
def collectRW[A, B, Repr, That](_this: TraversableLike[A, Repr])(pf: PartialFunction[A, B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
val repr: Repr = _this.asInstanceOf[Repr]
val b = bf(repr)
val f = pf runWith { b += _ }
_this foreach f
b.result
}
var cnt = 0
object Ex1 {
def unapply(x: Int) : Option[Int] = {
cnt += 1
if ((x % 3) == 0) Some(-x) else None
}
}
object Ex2 {
def unapply(x: Int) : Option[Int] = {
//cnt += 1
if ((x % 5) == 0) Some(x) else None
}
}
def resetCnt() = { val r = cnt; cnt = 0; r }
val pf: PartialFunction[Int,Int] = {
case Ex1(result) => result
case Ex2(result) => result
}
def collectTest() {
val xs = 1 to 100
resetCnt()
val ysIDA = collectIDA(xs)(pf)
val cntIDA = resetCnt()
val ysRW = collectRW(xs)(pf)
val cntRW = resetCnt()
val ys = xs collect pf
assert(ys == ysIDA)
assert(ys == ysRW)
assert(cntIDA == xs.length + ys.length)
assert(cntRW == xs.length)
println(ys.length)
println(cntIDA)
println(cntRW)
}
def orElseTest() {
val pf0 = new PartialFunction[Unit, Unit] {
def apply(u: Unit) { println("0:apply") }
def isDefinedAt(u: Unit) = { println("0:isDefinedAt"); false }
}
val pf1 = new PartialFunction[Unit, Unit] {
def apply(u: Unit) { println("1:apply") }
def isDefinedAt(u: Unit) = { println("1:isDefinedAt"); false }
}
val pf2 = new PartialFunction[Unit, Unit] {
def apply(u: Unit) { println("2:apply") }
def isDefinedAt(u: Unit) = { println("2:isDefinedAt"); true }
}
val chained = pf0 orElse pf1 orElse pf2
chained()
}
def main(args: Array[String]): Unit = {
collectTest()
orElseTest()
}
}
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