akka.util.Collections.scala Maven / Gradle / Ivy
/*
* Copyright (C) 2009-2019 Lightbend Inc.
*/
package akka.util
import scala.collection.immutable
import scala.annotation.tailrec
/**
* INTERNAL API
*/
private[akka] object Collections {
case object EmptyImmutableSeq extends immutable.Seq[Nothing] {
override final def iterator = Iterator.empty
override final def apply(idx: Int): Nothing = throw new java.lang.IndexOutOfBoundsException(idx.toString)
override final def length: Int = 0
}
abstract class PartialImmutableValuesIterable[From, To] extends immutable.Iterable[To] {
def isDefinedAt(from: From): Boolean
def apply(from: From): To
def valuesIterator: Iterator[From]
final def iterator: Iterator[To] = {
val superIterator = valuesIterator
new Iterator[To] {
private[this] var _next: To = _
private[this] var _hasNext = false
@tailrec override final def hasNext: Boolean =
if (!_hasNext && superIterator.hasNext) { // If we need and are able to look for the next value
val potentiallyNext = superIterator.next()
if (isDefinedAt(potentiallyNext)) {
_next = apply(potentiallyNext)
_hasNext = true
true
} else hasNext //Attempt to find the next
} else _hasNext // Return if we found one
override final def next(): To =
if (hasNext) {
val ret = _next
_next = null.asInstanceOf[To] // Mark as consumed (nice to the GC, don't leak the last returned value)
_hasNext = false // Mark as consumed (we need to look for the next value)
ret
} else throw new java.util.NoSuchElementException("next")
}
}
override lazy val size: Int = iterator.size
override def foreach[C](f: To => C) = iterator.foreach(f)
}
}
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