Renamed object RedBlack to RedBlackTree.

This more clearly separates the new implementation from the now
deprecated abstract class RedBlack and avoids naming conflicts
for the member classes.

2 files changed, 269 insertions, 56 deletions

diff --git a/test/files/scalacheck/redblack.scala b/test/files/scalacheck/redblack.scala
index 83d3ca0c1f..bbc6504f58 100644
--- a/test/files/scalacheck/redblack.scala
+++ b/test/files/scalacheck/redblack.scala
@@ -1,4 +1,3 @@
-import collection.immutable._
 import org.scalacheck._
 import Prop._
 import Gen._
@@ -15,23 +14,26 @@ Both children of every red node are black.
 Every simple path from a given node to any of its descendant leaves contains the same number of black nodes.
 */
 
-package scala.collection.immutable {
 abstract class RedBlackTest extends Properties("RedBlack") {
   def minimumSize = 0
   def maximumSize = 5
 
-  import RedBlack._
+  object RedBlackTest extends scala.collection.immutable.RedBlack[String] {
+    def isSmaller(x: String, y: String) = x < y
+  }
+
+  import RedBlackTest._
 
-  def nodeAt[A](tree: Node[String, A], n: Int): Option[(String, A)] = if (n < iterator(tree).size && n >= 0)
-    Some(iterator(tree).drop(n).next)
+  def nodeAt[A](tree: Tree[A], n: Int): Option[(String, A)] = if (n < tree.iterator.size && n >= 0)
+    Some(tree.iterator.drop(n).next)
   else
     None
 
-  def treeContains[A](tree: Node[String, A], key: String) = iterator(tree).map(_._1) contains key
+  def treeContains[A](tree: Tree[A], key: String) = tree.iterator.map(_._1) contains key
 
-  def mkTree(level: Int, parentIsBlack: Boolean = false, label: String = ""): Gen[Node[String, Int]] =
+  def mkTree(level: Int, parentIsBlack: Boolean = false, label: String = ""): Gen[Tree[Int]] =
     if (level == 0) {
-      value(null)
+      value(Empty)
     } else {
       for {
         oddOrEven <- choose(0, 2)
@@ -42,9 +44,9 @@ abstract class RedBlackTest extends Properties("RedBlack") {
         right <- mkTree(nextLevel, !isRed, label + "R")
       } yield {
         if (isRed)
-          RedNode(label + "N", 0, left, right)
+          RedTree(label + "N", 0, left, right)
         else
-          BlackNode(label + "N", 0, left, right)
+          BlackTree(label + "N", 0, left, right)
       }
     }
 
@@ -54,10 +56,10 @@ abstract class RedBlackTest extends Properties("RedBlack") {
   } yield tree
 
   type ModifyParm
-  def genParm(tree: Node[String, Int]): Gen[ModifyParm]
-  def modify(tree: Node[String, Int], parm: ModifyParm): Node[String, Int]
+  def genParm(tree: Tree[Int]): Gen[ModifyParm]
+  def modify(tree: Tree[Int], parm: ModifyParm): Tree[Int]
 
-  def genInput: Gen[(Node[String, Int], ModifyParm, Node[String, Int])] = for {
+  def genInput: Gen[(Tree[Int], ModifyParm, Tree[Int])] = for {
     tree <- genTree
     parm <- genParm(tree)
   } yield (tree, parm, modify(tree, parm))
@@ -66,30 +68,30 @@ abstract class RedBlackTest extends Properties("RedBlack") {
 trait RedBlackInvariants {
   self: RedBlackTest =>
 
-  import RedBlack._
+  import RedBlackTest._
 
-  def rootIsBlack[A](t: Node[String, A]) = isBlack(t)
+  def rootIsBlack[A](t: Tree[A]) = t.isBlack
 
-  def areAllLeavesBlack[A](t: Node[String, A]): Boolean = t match {
-    case null => isBlack(t)
-    case ne => List(ne.left, ne.right) forall areAllLeavesBlack
+  def areAllLeavesBlack[A](t: Tree[A]): Boolean = t match {
+    case Empty => t.isBlack
+    case ne: NonEmpty[_] => List(ne.left, ne.right) forall areAllLeavesBlack
   }
 
-  def areRedNodeChildrenBlack[A](t: Node[String, A]): Boolean = t match {
-    case RedNode(_, _, left, right) => List(left, right) forall (t => isBlack(t) && areRedNodeChildrenBlack(t))
-    case BlackNode(_, _, left, right) => List(left, right) forall areRedNodeChildrenBlack
-    case null => true
+  def areRedNodeChildrenBlack[A](t: Tree[A]): Boolean = t match {
+    case RedTree(_, _, left, right) => List(left, right) forall (t => t.isBlack && areRedNodeChildrenBlack(t))
+    case BlackTree(_, _, left, right) => List(left, right) forall areRedNodeChildrenBlack
+    case Empty => true
   }
 
-  def blackNodesToLeaves[A](t: Node[String, A]): List[Int] = t match {
-    case null => List(1)
-    case BlackNode(_, _, left, right) => List(left, right) flatMap blackNodesToLeaves map (_ + 1)
-    case RedNode(_, _, left, right) => List(left, right) flatMap blackNodesToLeaves
+  def blackNodesToLeaves[A](t: Tree[A]): List[Int] = t match {
+    case Empty => List(1)
+    case BlackTree(_, _, left, right) => List(left, right) flatMap blackNodesToLeaves map (_ + 1)
+    case RedTree(_, _, left, right) => List(left, right) flatMap blackNodesToLeaves
   }
 
-  def areBlackNodesToLeavesEqual[A](t: Node[String, A]): Boolean = t match {
-    case null => true
-    case ne =>
+  def areBlackNodesToLeavesEqual[A](t: Tree[A]): Boolean = t match {
+    case Empty => true
+    case ne: NonEmpty[_] =>
       (
         blackNodesToLeaves(ne).distinct.size == 1
         && areBlackNodesToLeavesEqual(ne.left)
@@ -97,10 +99,10 @@ trait RedBlackInvariants {
       )
   }
 
-  def orderIsPreserved[A](t: Node[String, A]): Boolean =
-    iterator(t) zip iterator(t).drop(1) forall { case (x, y) => x._1 < y._1 }
+  def orderIsPreserved[A](t: Tree[A]): Boolean =
+    t.iterator zip t.iterator.drop(1) forall { case (x, y) => isSmaller(x._1, y._1) }
 
-  def setup(invariant: Node[String, Int] => Boolean) = forAll(genInput) { case (tree, parm, newTree) =>
+  def setup(invariant: Tree[Int] => Boolean) = forAll(genInput) { case (tree, parm, newTree) =>
     invariant(newTree)
   }
 
@@ -112,13 +114,13 @@ trait RedBlackInvariants {
 }
 
 object TestInsert extends RedBlackTest with RedBlackInvariants {
-  import RedBlack._
+  import RedBlackTest._
 
   override type ModifyParm = Int
-  override def genParm(tree: Node[String, Int]): Gen[ModifyParm] = choose(0, iterator(tree).size + 1)
-  override def modify(tree: Node[String, Int], parm: ModifyParm): Node[String, Int] = update(tree, generateKey(tree, parm), 0)
+  override def genParm(tree: Tree[Int]): Gen[ModifyParm] = choose(0, tree.iterator.size + 1)
+  override def modify(tree: Tree[Int], parm: ModifyParm): Tree[Int] = tree update (generateKey(tree, parm), 0)
 
-  def generateKey(tree: Node[String, Int], parm: ModifyParm): String = nodeAt(tree, parm) match {
+  def generateKey(tree: Tree[Int], parm: ModifyParm): String = nodeAt(tree, parm) match {
     case Some((key, _)) => key.init.mkString + "MN"
     case None => nodeAt(tree, parm - 1) match {
       case Some((key, _)) => key.init.mkString + "RN"
@@ -132,31 +134,31 @@ object TestInsert extends RedBlackTest with RedBlackInvariants {
 }
 
 object TestModify extends RedBlackTest {
-  import RedBlack._
+  import RedBlackTest._
 
   def newValue = 1
   override def minimumSize = 1
   override type ModifyParm = Int
-  override def genParm(tree: Node[String, Int]): Gen[ModifyParm] = choose(0, iterator(tree).size)
-  override def modify(tree: Node[String, Int], parm: ModifyParm): Node[String, Int] = nodeAt(tree, parm) map {
-    case (key, _) => update(tree, key, newValue)
+  override def genParm(tree: Tree[Int]): Gen[ModifyParm] = choose(0, tree.iterator.size)
+  override def modify(tree: Tree[Int], parm: ModifyParm): Tree[Int] = nodeAt(tree, parm) map {
+    case (key, _) => tree update (key, newValue)
   } getOrElse tree
 
   property("update modifies values") = forAll(genInput) { case (tree, parm, newTree) =>
     nodeAt(tree,parm) forall { case (key, _) =>
-      iterator(newTree) contains (key, newValue)
+      newTree.iterator contains (key, newValue)
     }
   }
 }
 
 object TestDelete extends RedBlackTest with RedBlackInvariants  {
-  import RedBlack._
+  import RedBlackTest._
 
   override def minimumSize = 1
   override type ModifyParm = Int
-  override def genParm(tree: Node[String, Int]): Gen[ModifyParm] = choose(0, iterator(tree).size)
-  override def modify(tree: Node[String, Int], parm: ModifyParm): Node[String, Int] = nodeAt(tree, parm) map {
-    case (key, _) => delete(tree, key)
+  override def genParm(tree: Tree[Int]): Gen[ModifyParm] = choose(0, tree.iterator.size)
+  override def modify(tree: Tree[Int], parm: ModifyParm): Tree[Int] = nodeAt(tree, parm) map {
+    case (key, _) => tree delete key
   } getOrElse tree
 
   property("delete removes elements") = forAll(genInput) { case (tree, parm, newTree) =>
@@ -167,41 +169,40 @@ object TestDelete extends RedBlackTest with RedBlackInvariants  {
 }
 
 object TestRange extends RedBlackTest with RedBlackInvariants  {
-  import RedBlack._
+  import RedBlackTest._
 
   override type ModifyParm = (Option[Int], Option[Int])
-  override def genParm(tree: Node[String, Int]): Gen[ModifyParm] = for {
-    from <- choose(0, iterator(tree).size)
-    to <- choose(0, iterator(tree).size) suchThat (from <=)
+  override def genParm(tree: Tree[Int]): Gen[ModifyParm] = for {
+    from <- choose(0, tree.iterator.size)
+    to <- choose(0, tree.iterator.size) suchThat (from <=)
     optionalFrom <- oneOf(Some(from), None, Some(from)) // Double Some(n) to get around a bug
     optionalTo <- oneOf(Some(to), None, Some(to)) // Double Some(n) to get around a bug
   } yield (optionalFrom, optionalTo)
 
-  override def modify(tree: Node[String, Int], parm: ModifyParm): Node[String, Int] = {
+  override def modify(tree: Tree[Int], parm: ModifyParm): Tree[Int] = {
     val from = parm._1 flatMap (nodeAt(tree, _) map (_._1))
     val to = parm._2 flatMap (nodeAt(tree, _) map (_._1))
-    range(tree, from, to)
+    tree range (from, to)
   }
 
   property("range boundaries respected") = forAll(genInput) { case (tree, parm, newTree) =>
     val from = parm._1 flatMap (nodeAt(tree, _) map (_._1))
     val to = parm._2 flatMap (nodeAt(tree, _) map (_._1))
-    ("lower boundary" |: (from forall ( key => iterator(newTree).map(_._1) forall (key <=)))) &&
-    ("upper boundary" |: (to forall ( key => iterator(newTree).map(_._1) forall (key >))))
+    ("lower boundary" |: (from forall ( key => newTree.iterator.map(_._1) forall (key <=)))) &&
+    ("upper boundary" |: (to forall ( key => newTree.iterator.map(_._1) forall (key >))))
   }
 
   property("range returns all elements") = forAll(genInput) { case (tree, parm, newTree) =>
     val from = parm._1 flatMap (nodeAt(tree, _) map (_._1))
     val to = parm._2 flatMap (nodeAt(tree, _) map (_._1))
-    val filteredTree = (iterator(tree)
+    val filteredTree = (tree.iterator
       .map(_._1)
       .filter(key => from forall (key >=))
       .filter(key => to forall (key <))
       .toList)
-    filteredTree == iterator(newTree).map(_._1).toList
+    filteredTree == newTree.iterator.map(_._1).toList
   }
 }
-}
 
 object Test extends Properties("RedBlack") {
   include(TestInsert)
diff --git a/test/files/scalacheck/redblacktree.scala b/test/files/scalacheck/redblacktree.scala
new file mode 100644
index 0000000000..10f3f0fbbf
--- /dev/null
+++ b/test/files/scalacheck/redblacktree.scala
@@ -0,0 +1,212 @@
+import collection.immutable.{RedBlackTree => RB}
+import org.scalacheck._
+import Prop._
+import Gen._
+
+/*
+Properties of a Red & Black Tree:
+
+A node is either red or black.
+The root is black. (This rule is used in some definitions and not others. Since the
+root can always be changed from red to black but not necessarily vice-versa this
+rule has little effect on analysis.)
+All leaves are black.
+Both children of every red node are black.
+Every simple path from a given node to any of its descendant leaves contains the same number of black nodes.
+*/
+
+package scala.collection.immutable.redblacktree {
+  abstract class RedBlackTreeTest extends Properties("RedBlackTree") {
+    def minimumSize = 0
+    def maximumSize = 5
+
+    import RB._
+
+    def nodeAt[A](tree: Tree[String, A], n: Int): Option[(String, A)] = if (n < iterator(tree).size && n >= 0)
+      Some(iterator(tree).drop(n).next)
+    else
+      None
+
+    def treeContains[A](tree: Tree[String, A], key: String) = iterator(tree).map(_._1) contains key
+
+    def mkTree(level: Int, parentIsBlack: Boolean = false, label: String = ""): Gen[Tree[String, Int]] =
+      if (level == 0) {
+        value(null)
+      } else {
+        for {
+          oddOrEven <- choose(0, 2)
+          tryRed = oddOrEven.sample.get % 2 == 0 // work around arbitrary[Boolean] bug
+          isRed = parentIsBlack && tryRed
+          nextLevel = if (isRed) level else level - 1
+          left <- mkTree(nextLevel, !isRed, label + "L")
+          right <- mkTree(nextLevel, !isRed, label + "R")
+        } yield {
+          if (isRed)
+            RedTree(label + "N", 0, left, right)
+          else
+            BlackTree(label + "N", 0, left, right)
+        }
+      }
+
+    def genTree = for {
+      depth <- choose(minimumSize, maximumSize + 1)
+      tree <- mkTree(depth)
+    } yield tree
+
+    type ModifyParm
+    def genParm(tree: Tree[String, Int]): Gen[ModifyParm]
+    def modify(tree: Tree[String, Int], parm: ModifyParm): Tree[String, Int]
+
+    def genInput: Gen[(Tree[String, Int], ModifyParm, Tree[String, Int])] = for {
+      tree <- genTree
+      parm <- genParm(tree)
+    } yield (tree, parm, modify(tree, parm))
+  }
+
+  trait RedBlackTreeInvariants {
+    self: RedBlackTreeTest =>
+
+    import RB._
+
+    def rootIsBlack[A](t: Tree[String, A]) = isBlack(t)
+
+    def areAllLeavesBlack[A](t: Tree[String, A]): Boolean = t match {
+      case null => isBlack(t)
+      case ne => List(ne.left, ne.right) forall areAllLeavesBlack
+    }
+
+    def areRedNodeChildrenBlack[A](t: Tree[String, A]): Boolean = t match {
+      case RedTree(_, _, left, right) => List(left, right) forall (t => isBlack(t) && areRedNodeChildrenBlack(t))
+      case BlackTree(_, _, left, right) => List(left, right) forall areRedNodeChildrenBlack
+      case null => true
+    }
+
+    def blackNodesToLeaves[A](t: Tree[String, A]): List[Int] = t match {
+      case null => List(1)
+      case BlackTree(_, _, left, right) => List(left, right) flatMap blackNodesToLeaves map (_ + 1)
+      case RedTree(_, _, left, right) => List(left, right) flatMap blackNodesToLeaves
+    }
+
+    def areBlackNodesToLeavesEqual[A](t: Tree[String, A]): Boolean = t match {
+      case null => true
+      case ne =>
+        (
+          blackNodesToLeaves(ne).distinct.size == 1
+          && areBlackNodesToLeavesEqual(ne.left)
+          && areBlackNodesToLeavesEqual(ne.right)
+        )
+    }
+
+    def orderIsPreserved[A](t: Tree[String, A]): Boolean =
+      iterator(t) zip iterator(t).drop(1) forall { case (x, y) => x._1 < y._1 }
+
+    def setup(invariant: Tree[String, Int] => Boolean) = forAll(genInput) { case (tree, parm, newTree) =>
+      invariant(newTree)
+    }
+
+    property("root is black") = setup(rootIsBlack)
+    property("all leaves are black") = setup(areAllLeavesBlack)
+    property("children of red nodes are black") = setup(areRedNodeChildrenBlack)
+    property("black nodes are balanced") = setup(areBlackNodesToLeavesEqual)
+    property("ordering of keys is preserved") = setup(orderIsPreserved)
+  }
+
+  object TestInsert extends RedBlackTreeTest with RedBlackTreeInvariants {
+    import RB._
+
+    override type ModifyParm = Int
+    override def genParm(tree: Tree[String, Int]): Gen[ModifyParm] = choose(0, iterator(tree).size + 1)
+    override def modify(tree: Tree[String, Int], parm: ModifyParm): Tree[String, Int] = update(tree, generateKey(tree, parm), 0)
+
+    def generateKey(tree: Tree[String, Int], parm: ModifyParm): String = nodeAt(tree, parm) match {
+      case Some((key, _)) => key.init.mkString + "MN"
+      case None => nodeAt(tree, parm - 1) match {
+        case Some((key, _)) => key.init.mkString + "RN"
+        case None  => "N"
+      }
+    }
+
+    property("update adds elements") = forAll(genInput) { case (tree, parm, newTree) =>
+      treeContains(newTree, generateKey(tree, parm))
+    }
+  }
+
+  object TestModify extends RedBlackTreeTest {
+    import RB._
+
+    def newValue = 1
+    override def minimumSize = 1
+    override type ModifyParm = Int
+    override def genParm(tree: Tree[String, Int]): Gen[ModifyParm] = choose(0, iterator(tree).size)
+    override def modify(tree: Tree[String, Int], parm: ModifyParm): Tree[String, Int] = nodeAt(tree, parm) map {
+      case (key, _) => update(tree, key, newValue)
+    } getOrElse tree
+
+    property("update modifies values") = forAll(genInput) { case (tree, parm, newTree) =>
+      nodeAt(tree,parm) forall { case (key, _) =>
+        iterator(newTree) contains (key, newValue)
+      }
+    }
+  }
+
+  object TestDelete extends RedBlackTreeTest with RedBlackTreeInvariants  {
+    import RB._
+
+    override def minimumSize = 1
+    override type ModifyParm = Int
+    override def genParm(tree: Tree[String, Int]): Gen[ModifyParm] = choose(0, iterator(tree).size)
+    override def modify(tree: Tree[String, Int], parm: ModifyParm): Tree[String, Int] = nodeAt(tree, parm) map {
+      case (key, _) => delete(tree, key)
+    } getOrElse tree
+
+    property("delete removes elements") = forAll(genInput) { case (tree, parm, newTree) =>
+      nodeAt(tree, parm) forall { case (key, _) =>
+        !treeContains(newTree, key)
+      }
+    }
+  }
+
+  object TestRange extends RedBlackTreeTest with RedBlackTreeInvariants  {
+    import RB._
+
+    override type ModifyParm = (Option[Int], Option[Int])
+    override def genParm(tree: Tree[String, Int]): Gen[ModifyParm] = for {
+      from <- choose(0, iterator(tree).size)
+      to <- choose(0, iterator(tree).size) suchThat (from <=)
+      optionalFrom <- oneOf(Some(from), None, Some(from)) // Double Some(n) to get around a bug
+      optionalTo <- oneOf(Some(to), None, Some(to)) // Double Some(n) to get around a bug
+    } yield (optionalFrom, optionalTo)
+
+    override def modify(tree: Tree[String, Int], parm: ModifyParm): Tree[String, Int] = {
+      val from = parm._1 flatMap (nodeAt(tree, _) map (_._1))
+      val to = parm._2 flatMap (nodeAt(tree, _) map (_._1))
+      range(tree, from, to)
+    }
+
+    property("range boundaries respected") = forAll(genInput) { case (tree, parm, newTree) =>
+      val from = parm._1 flatMap (nodeAt(tree, _) map (_._1))
+      val to = parm._2 flatMap (nodeAt(tree, _) map (_._1))
+      ("lower boundary" |: (from forall ( key => iterator(newTree).map(_._1) forall (key <=)))) &&
+      ("upper boundary" |: (to forall ( key => iterator(newTree).map(_._1) forall (key >))))
+    }
+
+    property("range returns all elements") = forAll(genInput) { case (tree, parm, newTree) =>
+      val from = parm._1 flatMap (nodeAt(tree, _) map (_._1))
+      val to = parm._2 flatMap (nodeAt(tree, _) map (_._1))
+      val filteredTree = (iterator(tree)
+        .map(_._1)
+        .filter(key => from forall (key >=))
+        .filter(key => to forall (key <))
+        .toList)
+      filteredTree == iterator(newTree).map(_._1).toList
+    }
+  }
+}
+
+object Test extends Properties("RedBlackTree") {
+  import collection.immutable.redblacktree._
+  include(TestInsert)
+  include(TestModify)
+  include(TestDelete)
+  include(TestRange)
+}