--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/internal/Pool2.java	Fri Aug 19 03:36:25 2011 +0200
@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) 2011 TMate Software Ltd
+ *  
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * For information on how to redistribute this software under
+ * the terms of a license other than GNU General Public License
+ * contact TMate Software at support@hg4j.com
+ */
+package org.tmatesoft.hg.internal;
+
+import org.tmatesoft.hg.util.SparseSet;
+
+/**
+ *
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+public class Pool2<T> {
+	private final SparseSet<T> unify = new SparseSet<T>();
+	
+	public Pool2() {
+	}
+	
+	public Pool2(int sizeHint) {
+	}
+	
+	public T unify(T t) {
+		T rv = unify.get(t);
+		if (rv == null) {
+			// first time we see a new value
+			unify.put(t);
+			rv = t;
+		}
+		return rv;
+	}
+	
+	public boolean contains(T t) {
+		return unify.get(t) != null;
+	}
+	
+	public void record(T t) {
+		unify.put(t);
+	}
+	
+	public void clear() {
+		unify.clear();
+	}
+
+	public int size() {
+		return unify.size();
+	}
+	
+	public void x() {
+		unify.dump();
+	}
+
+	@Override
+	public String toString() {
+		StringBuilder sb = new StringBuilder();
+		sb.append(Pool2.class.getSimpleName());
+		sb.append('@');
+		sb.append(Integer.toString(System.identityHashCode(this)));
+		sb.append(' ');
+		sb.append(unify.toString());
+		return sb.toString();
+	}
+}