/* * Copyright (c) Contributors, http://opensimulator.org/ * See CONTRIBUTORS.TXT for a full list of copyright holders. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * Neither the name of the OpenSimulator Project nor the * names of its contributors may be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ using System; namespace OpenSim.Framework { /// <summary> /// Undo stack. Deletes entries beyond a certain capacity /// </summary> /// <typeparam name="T"></typeparam> [Serializable] public class UndoStack<T> { private int m_new = 1; private int m_old = 0; private T[] m_Undos; public UndoStack(int capacity) { m_Undos = new T[capacity + 1]; } public bool IsFull { get { return m_new == m_old; } } public int Capacity { get { return m_Undos.Length - 1; } } public int Count { get { int count = m_new - m_old - 1; if (count < 0) count += m_Undos.Length; return count; } } public void Push(T item) { if (IsFull) { m_old++; if (m_old >= m_Undos.Length) m_old -= m_Undos.Length; } if (++m_new >= m_Undos.Length) m_new -= m_Undos.Length; m_Undos[m_new] = item; } public T Pop() { if (Count > 0) { T deleted = m_Undos[m_new]; m_Undos[m_new--] = default(T); if (m_new < 0) m_new += m_Undos.Length; return deleted; } else throw new InvalidOperationException("Cannot pop from empty stack"); } public T Peek() { return m_Undos[m_new]; } public void Clear() { if (Count > 0) { for (int i = 0; i < m_Undos.Length; i++) { m_Undos[i] = default(T); } m_new = 1; m_old = 0; } } } }