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/*
* 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 emtpy 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;
}
}
}
}
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