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author | Adriaan Moors <adriaan.moors@typesafe.com> | 2013-12-08 21:01:27 -0800 |
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committer | Adriaan Moors <adriaan.moors@typesafe.com> | 2013-12-08 21:01:27 -0800 |
commit | 75cc6cf256df9e152eaec771121ce0db9f7039f8 (patch) | |
tree | 655acca49d7990fbc7c273d761ca942aa0ac651d /src | |
parent | 9751d19471c8ab7c1cc2a618fe097af9dddbd03b (diff) | |
parent | 58eadc09527c2b6722ddd830c0d3f319f2967ef7 (diff) | |
download | scala-75cc6cf256df9e152eaec771121ce0db9f7039f8.tar.gz scala-75cc6cf256df9e152eaec771121ce0db9f7039f8.tar.bz2 scala-75cc6cf256df9e152eaec771121ce0db9f7039f8.zip |
Merge pull request #3226 from ziggystar/patch-1
add method dequeueOption to immutable.Queue
Diffstat (limited to 'src')
-rw-r--r-- | src/library/scala/collection/immutable/Queue.scala | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/library/scala/collection/immutable/Queue.scala b/src/library/scala/collection/immutable/Queue.scala index 05c5dd799d..df1484c4ab 100644 --- a/src/library/scala/collection/immutable/Queue.scala +++ b/src/library/scala/collection/immutable/Queue.scala @@ -118,6 +118,13 @@ class Queue[+A] protected(protected val in: List[A], protected val out: List[A]) case x :: xs => (x, new Queue(in, xs)) case _ => throw new NoSuchElementException("dequeue on empty queue") } + + /** Optionally retrieves the first element and a queue of the remaining elements. + * + * @return A tuple of the first element of the queue, and a new queue with this element removed. + * If the queue is empty, `None` is returned. + */ + def dequeueOption: Option[(A, Queue[A])] = if(isEmpty) None else Some(dequeue) /** Returns the first element in the queue, or throws an error if there * is no element contained in the queue. |