--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/components/visual-panels/core/src/java/util/com/oracle/solaris/vp/util/misc/Stackable.java	Thu May 24 04:16:47 2012 -0400
@@ -0,0 +1,83 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2009, 2012, Oracle and/or its affiliates. All rights reserved.
+ */
+
+package com.oracle.solaris.vp.util.misc;
+
+/**
+ * The {@code Stackable} interface represents a last-in-first-out (LIFO) queue.
+ */
+public interface Stackable<E> {
+    /**
+     * Clears the stack.
+     */
+    void clear();
+
+    /**
+     * Gets the number of elements in the stack.
+     */
+    int getCount();
+
+    /**
+     * Gets the element at the top of the stack, or {@code null} if the stack
+     * contains no elements
+     */
+    E peek();
+
+    /**
+     * Gets the element at the top of the stack.  Equivalent to {@link
+     * #peekOrErr peekOrErr}{@code (0)};
+     *
+     * @exception   NoSuchElementException
+     *		    if the stack contains no elements
+     */
+    E peekOrErr();
+
+    /**
+     * Gets the {@code n}th element at the top of the stack.
+     *
+     * @param	    n
+     *		    an integer between 0 and {@link #getCount getCount()} {@code
+     *		    - 1}, inclusive
+     *
+     * @exception   NoSuchElementException
+     *		    if n is invalid
+     */
+    E peekOrErr(int n);
+
+    /**
+     * Removes the element at the top of the stack.
+     *
+     * @return	    the removed element
+     *
+     * @exception   NoSuchElementException
+     *		    if the stack contains no elements
+     */
+    E pop();
+
+    /**
+     * Adds the given element to the stack.
+     */
+    void push(E element);
+}