1 files changed, 151 insertions, 0 deletions
diff --git a/src/org/clojure/runtime/RBSet.java b/src/org/clojure/runtime/RBSet.java
new file mode 100644
index 00000000..24c6aa71
--- /dev/null
+++ b/src/org/clojure/runtime/RBSet.java
@@ -0,0 +1,151 @@
+/**
+ *   Copyright (c) Rich Hickey. All rights reserved.
+ *   The use and distribution terms for this software are covered by the
+ *   Common Public License 1.0 (http://opensource.org/licenses/cpl.php)
+ *   which can be found in the file CPL.TXT at the root of this distribution.
+ *   By using this software in any fashion, you are agreeing to be bound by
+ * 	 the terms of this license.
+ *   You must not remove this notice, or any other, from this software.
+ **/
+
+/* rich May 20, 2006 */
+
+package org.clojure.runtime;
+
+import java.util.Comparator;
+
+public class RBSet{
+
+public final Comparator comp;
+public final Node tree;
+public final int count;
+
+public RBSet(Comparator comp)
+	{
+	this.comp = comp;
+	tree = null;
+	count = 0;
+	}
+
+public boolean contains(Object x)
+	{
+	return treeContains(tree,x);
+	}
+
+public RBSet add(Object x)
+	{
+	Node t = treeInsert(tree,x);
+	if(t == null)   //null == already contains x
+		return this;
+	return new RBSet(comp, t, count + 1);
+	}
+
+Node treeInsert(Node t, Object x)
+	{
+	if(t == null)
+		return red(x, null, null);
+	int c = comp.compare(t.key,x);
+	if(c == 0)
+		return null;
+	Node ins = c < 0 ? treeInsert(t.left, x) : treeInsert(t.right, x);
+	if(ins == null) //found below
+		return null;
+	if(t instanceof Black)
+		{
+		if(c < 0)
+			return leftBalance(x, ins, t.right);
+		return rightBalance(x, t.left, ins);
+		}
+	else //Red
+		{
+		if(c < 0)
+			return red(x, ins, t.right);
+		return red(x, t.left, ins);
+		}
+	}
+
+Node leftBalance(Object x, Node left, Node right)
+	{
+	if(left instanceof Red && left.left instanceof Red)
+		return red(left.key, blacken(left.left), black(x, left.right, right));
+	else if(left instanceof Red && left.right instanceof Red)
+		return red(left.right.key, black(left.key,left.left, left.right.left), black(x, left.right.right, right));
+	else
+		return black(x, left, right);
+	}
+
+Node rightBalance(Object x, Node left, Node right)
+	{
+	if(right instanceof Red && right.right instanceof Red)
+		return red(right.key, black(x, left, right.left), blacken(right.right));
+	else if(right instanceof Red && right.left instanceof Red)
+		return red(right.right.key, black(x, left, right.left.left), black(right.key, right.left.right, right));
+	else
+		return black(x, left, right);
+	}
+
+
+Node blacken(Node n)
+	{
+	return black(n.key, n.left, n.right);
+	}
+
+boolean treeContains(Node t,Object x)
+	{
+	if(t == null)
+		return false;
+	int c = comp.compare(t.key,x);
+	if(c == 0)
+		return true;
+	else if(c < 0)
+		return treeContains(t.left, x);
+	return treeContains(t.right, x);
+	}
+
+RBSet(Comparator comp, Node tree, int count)
+	{
+	this.comp = comp;
+	this.tree = tree;
+	this.count = count;
+	}
+
+static Red red(Object key,Node left,Node right)
+	{
+	return new Red(key, left, right);
+	}
+
+static Black black(Object key,Node left,Node right)
+	{
+	return new Black(key, left, right);
+	}
+
+static public class Node{
+	public Object key;
+	public Node left;
+	public Node right;
+	public Node(Object key,Node left,Node right)
+		{
+		this.key = key;
+		this.left = left;
+		this.right = right;
+		}
+}
+
+static public class Red extends Node{
+	public Red(Object key,Node left,Node right)
+		{
+		super(key, left, right);
+		}
+
+}
+
+static public class Black extends Node{
+	public Black(Object key,Node left,Node right)
+		{
+		super(key, left, right);
+		}
+
+}
+
+
+}