fixed #790

1 files changed, 20 insertions, 0 deletions

diff --git a/src/library/scala/RandomAccessSeq.scala b/src/library/scala/RandomAccessSeq.scala
index 66faeb10e1..437d7ae8fb 100644
--- a/src/library/scala/RandomAccessSeq.scala
+++ b/src/library/scala/RandomAccessSeq.scala
@@ -10,6 +10,8 @@
 
 package scala
 
+import collection.mutable.ArrayBuffer
+
 object RandomAccessSeq {
   trait Projection[+A] extends Seq.Projection[A] with RandomAccessSeq[A] {
     override def projection = this
@@ -161,6 +163,24 @@ trait RandomAccessSeq[+A] extends Seq[A] {
     override def reverse : RandomAccessSeq.Projection[A] = RandomAccessSeq.this.projection
   }
 
+  /** Partitions this random access sequence in two random access
+   *  sequences according to a predicate.
+   *
+   *  @param p the predicate on which to partition
+   *  @return  a pair of random access sequences: the sequence of all elements
+   *           that satisfy the predicate <code>p</code> and the sequence of
+   *           all elements that do not.
+   *           The relative order of the elements in the resulting sequences
+   *           is the same as in the original sequence.
+   */
+  override def partition(p: A => Boolean): (RandomAccessSeq[A], RandomAccessSeq[A]) = {
+    val matched = new ArrayBuffer[A]
+    val failed = new ArrayBuffer[A]
+    val elems = elements
+    while (elems.hasNext) { val x = elems.next; if (p(x)) matched += x else failed += x }
+    (matched, failed)
+  }
+
   /** insert segment <code>patch</code> into this sequence at <code>from</code>
    *  replacing  <code>replaced</code> elements. The result is a projection.
    */