1 files changed, 16 insertions, 10 deletions
diff --git a/src/library/scala/collection/IndexedSeqOptimized.scala b/src/library/scala/collection/IndexedSeqOptimized.scala
index 09c4b14ba0..a7e06b4d1a 100755
--- a/src/library/scala/collection/IndexedSeqOptimized.scala
+++ b/src/library/scala/collection/IndexedSeqOptimized.scala
@@ -33,11 +33,17 @@ trait IndexedSeqOptimized[+A, +Repr] extends Any with IndexedSeqLike[A, Repr] {
     while (i < len) { f(this(i)); i += 1 }
   }
 
+  private def prefixLengthImpl(p: A => Boolean, expectTrue: Boolean): Int = {
+    var i = 0
+    while (i < length && p(apply(i)) == expectTrue) i += 1
+    i
+  }
+
   override /*IterableLike*/
-  def forall(p: A => Boolean): Boolean = prefixLength(p(_)) == length
+  def forall(p: A => Boolean): Boolean = prefixLengthImpl(p, expectTrue = true) == length
 
   override /*IterableLike*/
-  def exists(p: A => Boolean): Boolean = prefixLength(!p(_)) != length
+  def exists(p: A => Boolean): Boolean = prefixLengthImpl(p, expectTrue = false) != length
 
   override /*IterableLike*/
   def find(p: A => Boolean): Option[A] = {
@@ -82,7 +88,7 @@ trait IndexedSeqOptimized[+A, +Repr] extends Any with IndexedSeqLike[A, Repr] {
         b += ((this(i), that(i).asInstanceOf[B]))
         i += 1
       }
-      b.result
+      b.result()
     case _ =>
       super.zip[A1, B, That](that)(bf)
   }
@@ -97,7 +103,7 @@ trait IndexedSeqOptimized[+A, +Repr] extends Any with IndexedSeqLike[A, Repr] {
       b += ((this(i), i))
       i += 1
     }
-    b.result
+    b.result()
   }
 
   override /*IterableLike*/
@@ -113,7 +119,7 @@ trait IndexedSeqOptimized[+A, +Repr] extends Any with IndexedSeqLike[A, Repr] {
       b += self(i)
       i += 1
     }
-    b.result
+    b.result()
   }
 
   override /*IterableLike*/
@@ -135,10 +141,10 @@ trait IndexedSeqOptimized[+A, +Repr] extends Any with IndexedSeqLike[A, Repr] {
   def drop(n: Int): Repr = slice(n, length)
 
   override /*IterableLike*/
-  def takeRight(n: Int): Repr = slice(length - n, length)
+  def takeRight(n: Int): Repr = slice(length - math.max(n, 0), length)
 
   override /*IterableLike*/
-  def dropRight(n: Int): Repr = slice(0, length - n)
+  def dropRight(n: Int): Repr = slice(0, length - math.max(n, 0))
 
   override /*TraversableLike*/
   def splitAt(n: Int): (Repr, Repr) = (take(n), drop(n))
@@ -200,7 +206,7 @@ trait IndexedSeqOptimized[+A, +Repr] extends Any with IndexedSeqLike[A, Repr] {
 
   override /*SeqLike*/
   def lastIndexWhere(p: A => Boolean, end: Int): Int = {
-    var i = end
+    var i = math.min(end, length - 1)
     while (i >= 0 && !p(this(i))) i -= 1
     i
   }
@@ -214,7 +220,7 @@ trait IndexedSeqOptimized[+A, +Repr] extends Any with IndexedSeqLike[A, Repr] {
       i -= 1
       b += this(i)
     }
-    b.result
+    b.result()
   }
 
   override /*SeqLike*/
@@ -225,7 +231,7 @@ trait IndexedSeqOptimized[+A, +Repr] extends Any with IndexedSeqLike[A, Repr] {
       if (0 < i) {
         i -= 1
         self(i)
-      } else Iterator.empty.next
+      } else Iterator.empty.next()
   }
 
   override /*SeqLike*/