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