diff options
| -rw-r--r-- | src/library/scala/Stream.scala | 41 |
1 files changed, 25 insertions, 16 deletions
diff --git a/src/library/scala/Stream.scala b/src/library/scala/Stream.scala index 6ecc9b768c..2e21fc27c1 100644 --- a/src/library/scala/Stream.scala +++ b/src/library/scala/Stream.scala @@ -32,23 +32,32 @@ object Stream { protected def addDefinedElems(buf: StringBuilder, prefix: String): StringBuilder = buf } - /** A stream consisting of a given first element and remaining elements - * @param hd The first element of the result stream - * @param tl The remaining elements of the result stream - */ - def cons[a](hd: a, tl: => Stream[a]) = new Stream[a] { - override def isEmpty = false - def head = hd - private var tlVal: Stream[a] = _ - private var tlDefined = false - def tail: Stream[a] = { - if (!tlDefined) { tlVal = tl; tlDefined = true } - tlVal - } - protected def addDefinedElems(buf: StringBuilder, prefix: String): StringBuilder = { - val buf1 = buf.append(prefix).append(hd) - if (tlDefined) tlVal.addDefinedElems(buf1, ", ") else buf1 append ", ?" + + object cons { + /** A stream consisting of a given first element and remaining elements + * @param hd The first element of the result stream + * @param tl The remaining elements of the result stream + */ + def apply[a](hd: a, tl: => Stream[a]) = new Stream[a] { + override def isEmpty = false + def head = hd + private var tlVal: Stream[a] = _ + private var tlDefined = false + def tail: Stream[a] = { + if (!tlDefined) { tlVal = tl; tlDefined = true } + tlVal + } + protected def addDefinedElems(buf: StringBuilder, prefix: String): StringBuilder = { + val buf1 = buf.append(prefix).append(hd) + if (tlDefined) tlVal.addDefinedElems(buf1, ", ") else buf1 append ", ?" + } } + + def unapply[a](str: Stream[a]): Option[{a,Stream[a]}] = + if(str.isEmpty) + None + else + Some({str.head, str.tail}) } /** A stream containing all elements of a given iterator, in the order they are produced. |