From 3045b84c8c36d25a3936a114e77a2ae1488ec313 Mon Sep 17 00:00:00 2001
From: Donna Malayeri <lindydonna@gmail.com>
Date: Mon, 23 Nov 2009 15:16:25 +0000
Subject: Closed #2552.

---
 src/library/scala/collection/Iterator.scala | 32 +++++++++++++++----
 test/files/run/bug2552.check                | 49 +++++++++++++++++++++++++++++
 test/files/run/bug2552.scala                | 34 ++++++++++++++++++++
 3 files changed, 109 insertions(+), 6 deletions(-)
 create mode 100644 test/files/run/bug2552.check
 create mode 100644 test/files/run/bug2552.scala

diff --git a/src/library/scala/collection/Iterator.scala b/src/library/scala/collection/Iterator.scala
index 751d084770..70462cb8d2 100644
--- a/src/library/scala/collection/Iterator.scala
+++ b/src/library/scala/collection/Iterator.scala
@@ -355,10 +355,19 @@ trait Iterator[+A] { self =>
   def filter(p: A => Boolean): Iterator[A] = {
     val self = buffered
     new Iterator[A] {
-      private def skip() = while (self.hasNext && !p(self.head)) self.next()
-      def hasNext = { skip(); self.hasNext }
-      def next() = { skip(); self.next() }
-    }
+			var computedHasNext = false
+      private def skip() = {
+				while (self.hasNext && !p(self.head)) self.next()
+				computedHasNext = self.hasNext
+			}
+      def hasNext = { if (!computedHasNext) skip(); computedHasNext }
+      def next() = {
+				if (!computedHasNext)
+					skip()
+				computedHasNext = false
+				self.next()
+    	}
+		}
   }
 
   /** !!! Temporary, awaiting more general implementation.
@@ -401,8 +410,19 @@ trait Iterator[+A] { self =>
   def takeWhile(p: A => Boolean): Iterator[A] = {
     val self = buffered
     new Iterator[A] {
-      def hasNext = { self.hasNext && p(self.head) }
-      def next() = (if (hasNext) self else empty).next()
+			var computedHasNext = false
+
+      def hasNext = {
+				val result = computedHasNext || (self.hasNext && p(self.head))
+				computedHasNext = result
+				result
+			}
+
+      def next() = {
+				val result = (if (computedHasNext || hasNext) self else empty).next()
+				computedHasNext = false
+				result
+			}
     }
   }
 
diff --git a/test/files/run/bug2552.check b/test/files/run/bug2552.check
new file mode 100644
index 0000000000..774e360d13
--- /dev/null
+++ b/test/files/run/bug2552.check
@@ -0,0 +1,49 @@
+p(0)
+0
+p(1)
+1
+p(2)
+2
+p(3)
+3
+p(4)
+4
+p(5)
+5
+p(6)
+6
+p(7)
+7
+p(8)
+8
+p(9)
+9
+p(10)
+p(0)
+true
+true
+0
+p(1)
+true
+1
+p(2)
+false
+p(2)
+false
+p(0)
+true
+true
+0
+p(1)
+p(2)
+2
+p(3)
+p(4)
+4
+p(5)
+p(6)
+6
+p(7)
+p(8)
+8
+p(9)
diff --git a/test/files/run/bug2552.scala b/test/files/run/bug2552.scala
new file mode 100644
index 0000000000..911d98decc
--- /dev/null
+++ b/test/files/run/bug2552.scala
@@ -0,0 +1,34 @@
+object Test extends Application {
+	def testTakeWhile = {
+		val numbers = Iterator.range(0, 50)
+		val zeroTo9 = numbers.takeWhile(x => { println("p(" + x + ")"); x < 10 } )
+
+		zeroTo9.foreach(println _)
+
+		val zeroTo1 = Iterator.range(0, 20).takeWhile(x => { println("p(" + x + ")"); x < 2 } )
+
+		println(zeroTo1.hasNext)
+		println(zeroTo1.hasNext)
+		println(zeroTo1.next)
+		println(zeroTo1.hasNext)
+		println(zeroTo1.next)
+		println(zeroTo1.hasNext)
+		println(zeroTo1.hasNext)
+	}
+
+	def testFilter = {
+		val predicate = (x: Int) => { println("p(" + x + ")"); x % 2 == 0 }
+
+		val evens = Iterator.range(0, 10).filter(predicate)
+
+		println(evens.hasNext)
+		println(evens.hasNext)
+		println(evens.next)
+
+		evens.foreach(println _)
+	}
+
+	testTakeWhile
+	testFilter
+}
+
-- 
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