Improved documentation for scala.collection.imm...

Improved documentation for scala.collection.immutable.List and
scala.collection.immutable.Queue. Contributed by Matthew Pocock during
the Monthly Docspree. Review by phaller.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/library/scala/collection/immutable/Queue.scala b/src/library/scala/collection/immutable/Queue.scala
index 892f75ae91..813497f994 100644
--- a/src/library/scala/collection/immutable/Queue.scala
+++ b/src/library/scala/collection/immutable/Queue.scala
@@ -16,6 +16,14 @@ import annotation.tailrec
 /** `Queue` objects implement data structures that allow to
  *  insert and retrieve elements in a first-in-first-out (FIFO) manner.
  *
+ *  `Queue` is implemented as a pair of `List`s, one containing the ''in'' elements and the other the ''out'' elements.
+ *  Elements are added to the ''in'' list and removed from the ''out'' list. When the ''out'' list runs dry, the
+ *  queue is pivoted by replacing the ''out'' list by ''in.reverse'', and ''in'' by ''Nil''.
+ *
+ *  Adding items to the queue always has cost `O(1)`. Removing items has cost `O(1)`, except in the case
+ *  where a pivot is required, in which case, a cost of `O(n)` is incurred, where `n` is the number of elements in the queue. When this happens,
+ *  `n` remove operations with `O(1)` cost are guaranteed. Removing an item is on average `O(1)`.
+ *
  *  @author  Erik Stenman
  *  @version 1.0, 08/07/2003
  *  @since   1
@@ -24,6 +32,7 @@ import annotation.tailrec
  *  @define mayNotTerminateInf
  *  @define willNotTerminateInf
  */
+
 @SerialVersionUID(-7622936493364270175L)
 class Queue[+A] protected(protected val in: List[A], protected val out: List[A])
             extends LinearSeq[A]