1 files changed, 139 insertions, 1 deletions
diff --git a/src/library/scalax/collection/generic/OrderedIterableTemplate.scala b/src/library/scalax/collection/generic/OrderedIterableTemplate.scala
index 9e61daa418..501cbf6447 100755
--- a/src/library/scalax/collection/generic/OrderedIterableTemplate.scala
+++ b/src/library/scalax/collection/generic/OrderedIterableTemplate.scala
@@ -13,6 +13,8 @@ package scalax.collection.generic
 
 import OrderedIterable._
 
+import util.control.Breaks._
+
 /** Ordered iterables are iterables where the `elements` method always returns elements in the same
  *  order (namely the order in which elements were appended to the iterable). In particular, one has
  *  for every two ordered iterables `xs` and `ys`:
@@ -20,4 +22,140 @@ import OrderedIterable._
  *  `(xs ++ ys).elements = xs.elements ++ ys.elements
  */
 trait OrderedIterableTemplate[+CC[/*+*/B] <: OrderedIterableTemplate[CC, B] with OrderedIterable[B], /*+*/A]
-  extends IterableTemplate[CC, A]
+  extends IterableTemplate[CC, A] {
+
+  /** The last element of this iterable.
+   *
+   *  @throws Predef.NoSuchElementException if the iterable is empty.
+   *  @note  Might return different results for different runs, unless this iterable is ordered
+   */
+  def last: A = {
+    var lst = head
+    for (x <- this)
+      lst = x
+    lst
+  }
+
+  /** Returns as an option the last element of this iterable or
+   *  <code>None</code> if iterable is empty.
+   *
+   *  @return the last element as an option.
+   *  @note  Might return different results for different runs, unless this iterable is ordered
+   */
+  def lastOption: Option[A] = if (isEmpty) None else Some(last)
+
+  /** An iterable consisting of all elements of this iterable except the last one.
+   *  @throws Predef.UnsupportedOperationException if the stream is empty.
+   *  @note  Might return different results for different runs, unless this iterable is ordered
+   */
+  def init: CC[A] = {
+    if (isEmpty) throw new UnsupportedOperationException("empty.init")
+    var lst = head
+    val b = newBuilder[A]
+    for (x <- this) {
+      b += lst
+      lst = x
+    }
+    b.result
+  }
+
+  /** Returns the rightmost <code>n</code> elements from this iterable.
+   *
+   *  @param n the number of elements to take
+   *  @note  Might return different results for different runs, unless this iterable is ordered
+   */
+  def takeRight(n: Int): CC[A] = {
+    val b = newBuilder[A]
+    val lead = elements drop n
+    var go = false
+    for (x <- this) {
+      if (go) b += x
+      else if (lead.hasNext) lead.next
+      else go = true
+    }
+    b.result
+  }
+
+  /** Returns the iterable wihtout its rightmost <code>n</code> elements.
+   *
+   *  @param n the number of elements to take
+   *  @note  Might return different results for different runs, unless this iterable is ordered
+   */
+  def dropRight(n: Int): CC[A] = {
+    val b = newBuilder[A]
+    val lead = elements drop n
+    breakable {
+      for (x <- this) {
+        if (!lead.hasNext) break
+        lead.next
+        b += x
+      }
+    }
+    b.result
+  }
+
+  /** Returns the longest prefix of this iterable whose elements satisfy
+   *  the predicate <code>p</code>.
+   *
+   *  @param p the test predicate.
+   *  @note  Might return different results for different runs, unless this iterable is ordered
+   */
+  def takeWhile(p: A => Boolean): CC[A] = {
+    val b = newBuilder[A]
+    breakable {
+      for (x <- this) {
+        if (!p(x)) break
+        b += x
+      }
+    }
+    b.result
+  }
+
+  /** Returns the longest suffix of this iterable whose first element
+   *  does not satisfy the predicate <code>p</code>.
+   *
+   *  @param p the test predicate.
+   *  @note  Might return different results for different runs, unless this iterable is ordered
+   */
+  def dropWhile(p: A => Boolean): CC[A] = {
+    val b = newBuilder[A]
+    var go = false
+    for (x <- this) {
+      if (go) b += x
+      else if (!p(x)) { go = true; b += x }
+    }
+    b.result
+  }
+
+ /** Returns a pair consisting of the longest prefix of the iterable whose
+   *  elements all satisfy the given predicate, and the rest of the iterable.
+   *
+   *  @param p the test predicate
+   *  @return  a pair consisting of the longest prefix of the iterable whose
+   *           elements all satisfy <code>p</code>, and the rest of the iterable.
+   *  @note  Might return different results for different runs, unless this iterable is ordered
+   */
+  def span(p: A => Boolean): (CC[A], CC[A]) = {
+    val l, r = newBuilder[A]
+    var toLeft = true
+    for (x <- this) {
+      toLeft = toLeft && p(x)
+      (if (toLeft) l else r) += x
+    }
+    (l.result, r.result)
+  }
+
+  /** Checks if the other iterable object contains the same elements as this one.
+   *
+   *  @note will not terminate for infinite-sized iterables.
+   *  @param that  the other iterable
+   *  @return true, iff both iterables contain the same elements.
+   *  @note  Might return different results for different runs, unless this iterable is ordered
+   */
+  def sameElements[B >: A](that: OrderedIterable[B]): Boolean = {
+    val these = this.elements
+    val those = that.elements
+    while (these.hasNext && those.hasNext && these.next() == those.next()) {}
+    !these.hasNext && !those.hasNext
+  }
+}