Make Iterator.toStream be properly lazy.

3 files changed, 16 insertions, 7 deletions

diff --git a/src/library/scala/collection/Iterator.scala b/src/library/scala/collection/Iterator.scala
index daa6a59f3b..b8dd03110d 100644
--- a/src/library/scala/collection/Iterator.scala
+++ b/src/library/scala/collection/Iterator.scala
@@ -1007,6 +1007,9 @@ trait Iterator[+A] extends TraversableOnce[A] {
 
   def toTraversable: Traversable[A] = toStream
   def toIterator: Iterator[A] = self
+  def toStream: Stream[A] =
+    if (self.hasNext) Stream.cons(self.next, self.toStream)
+    else Stream.empty[A]
 
   /** Converts this iterator to a string.
    *  @return `"empty iterator"` or `"non-empty iterator"`, depending on whether or not the iterator is empty.
diff --git a/src/library/scala/collection/TraversableLike.scala b/src/library/scala/collection/TraversableLike.scala
index 50259a1ee8..88a6379da2 100644
--- a/src/library/scala/collection/TraversableLike.scala
+++ b/src/library/scala/collection/TraversableLike.scala
@@ -696,6 +696,12 @@ trait TraversableLike[+A, +Repr] extends HasNewBuilder[A, Repr] with Traversable
   def toTraversable: Traversable[A] = thisCollection
   def toIterator: Iterator[A] = toIterable.iterator
 
+  /** Converts this $coll to a stream.
+   *  $willNotTerminateInf
+   *  @return a stream containing all elements of this $coll.
+   */
+  def toStream: Stream[A] = toIterable.toStream
+
   /** Converts this $coll to a string.
    *  @return   a string representation of this collection. By default this
    *            string consists of the `stringPrefix` of this $coll,
diff --git a/src/library/scala/collection/TraversableOnce.scala b/src/library/scala/collection/TraversableOnce.scala
index 3984264168..1797ff39db 100644
--- a/src/library/scala/collection/TraversableOnce.scala
+++ b/src/library/scala/collection/TraversableOnce.scala
@@ -66,6 +66,12 @@ trait TraversableOnce[+A] {
    */
   def toTraversable: Traversable[A]
 
+  /** Converts this $coll to a stream.
+   *  $willNotTerminateInf
+   *  @return a stream containing all elements of this $coll.
+   */
+  def toStream: Stream[A]
+
   /** Presently these are abstract because the Traversable versions use
    *  breakable/break, and I wasn't sure enough of how that's supposed to
    *  function to consolidate them with the Iterator versions.
@@ -383,7 +389,7 @@ trait TraversableOnce[+A] {
       copyToArray(result, 0)
       result
     }
-    else toStream.toArray
+    else toBuffer.toArray
   }
 
   /** Converts this $coll to a list.
@@ -416,12 +422,6 @@ trait TraversableOnce[+A] {
    */
   def toBuffer[B >: A]: mutable.Buffer[B] = new ArrayBuffer[B] ++= self
 
-  /** Converts this $coll to a stream.
-   *  $willNotTerminateInf
-   *  @return a stream containing all elements of this $coll.
-   */
-  def toStream: Stream[A] = toList.toStream
-
   /** Converts this $coll to a set.
    *  $willNotTerminateInf
    *  @return      a set containing all elements of this $coll.